Chemotherapy-induced cognitive impairment (CICI), chemobrain, and chemofog are the common terms for mental dysfunction in a cancer patient/survivor under the influence of chemotherapeutics. CICI is manifested as short/long term memory problems and delayed mental processing, which interferes with a person’s day-to-day activities. Understanding CICI mechanisms help in developing therapeutic interventions that may alleviate the disease condition. Animal models facilitate critical evaluation to elucidate the underlying mechanisms and form an integral part of verifying different treatment hypotheses and strategies.A methodical evaluation of scientific literature is required to understand cognitive changes associated with the use of chemotherapeutic agents in different preclinical studies. This review mainly emphasizes animal models developed with various chemotherapeutic agents individually and in combination, with their proposed mechanisms contributing to the cognitive dysfunction. This review also points toward the analysis of chemobrain in healthy animals to understand the mechanism of interventions in absence of tumor and in tumor-bearing animals to mimic human cancer conditions to screen potential drug candidates against chemobrain.Substantial memory deficit as a result of commonly used chemotherapeutic agents was evidenced in healthy and tumor-bearing animals. Spatial and episodic cognitive impairments, alterations in neurotrophins, oxidative and inflammatory markers, and changes in long-term potentiation were commonly observed changes in different animal models irrespective of the chemotherapeutic agent.Dyscognition exists as one of the serious side effects of cancer chemotherapy. Due to differing mechanisms of chemotherapeutic agents with differing tendencies to alter behavioral and biochemical parameters, chemotherapy may present a significant risk in resulting memory impairments in healthy as well as tumor-bearing animals. Cancer is referred as “the modern disease par excellence” or “the quintessential product of modernity.” Although it is considered a modern disease, evidence of its existence in humans and other animals has been found throughout recorded history. Analyzing the timeline of events related to cancer chemotherapy, the beginning of the twentieth century marked the development of cancer models in rodents. Despite the introduction of radical methods like X-rays that focused on the complete eradication of the disease, a crucial turning point for cancer treatment was reached in the 1940s during World War II (WWII).This period initiated chemotherapy, which represented the basis for developing and synthesizing compounds as therapeutic interventions in cancer patients. The discovery of nitrogen mustard during WWII led scientists like Alfred Gilman and Lewis Goodman to examine its therapeutic effects in mice bearing transplanted lymphoid tumors. The post-war drug development program encouraged and introduced different categories of chemotherapeutic agents like folate antagonists and antimitotic agents. In the late 1960s and 1970s, the idea of combination therapy involving multiple drugs with varying mechanisms of action led to further patient improvement and minimal toxicity. Freireich and others designed a program known as VAMP  as first in class series of cyclically administered drug treatments that significantly increased the remission rate in children with leukemia. Thereby, studies on combination therapy have eventually paved the way for developing antitumor polychemotherapy, which achieved better therapeutic efficacy over single agents  . This allows the cytotoxic concentrations of the drugs to reach the brain, causing oxidative stress and structural and functional changes in different brain areas  that cause perturbance in the executive and memory functions Holmes . HippocaStudies related to chemobrain in humans have limitations because the methodology and small sample sizes of the neuroimaging studies only confirm the existence of cognitive impairment but do not directly describe the mechanism of neuronal injury. Animal models of chemobrain give not only about the critical aspects of pathogenesis but also in assessing the therapeutic efficacy of different agents in attenuating CICI. In a clinical setting, the treatment approach usually involves a blend of chemotherapeutic drugs, making it difficult to assess the individual toxicity or the synergistic effect of different agents. But preclinical conditions aid in evaluating the agents individually and in turn determine their specific mode of actions. Preclinical models also allow us to control variables like age, sex, environment, cancer type, treatment regimens, and comorbid conditions, which are often to be dealt with caution in a clinical setting. Different laboratories can also use distinct strategies to understand CICI, such as using various chemotherapeutic agents, behavioral testing delays, and pharmacological and non-pharmacological therapies through various animal models. However, the development of animal models for CICI is challenging because it is difficult to mimic the human disease, which comprehensively explains the complexities of behavioral, cognitive, and immunological aspects of chemobrain . Only those studies that describe the behavioral and biochemical tests for establishing the effect of chemotherapy on cognitive function in animals were included in preparing the manuscript. Studies that report the role of surgery, radiation, and hormone replacement therapy on cognitive function were excluded from the data analysis.Single therapy chemobrain models provide a precise mechanism of the respective chemotherapeutic agent responsible for inducing cognitive deficits. In addition, the effect of commonly used chemotherapeutic agents in healthy animals may predict the extent of dyscognition caused by each agent in the absence of a tumor. This sort of analysis is necessary to develop treatment strategies that can improve cancer survivors’ quality of life.Doxorubicin (DOX) is a ruling chemotherapeutic agent used in several carcinomas like ovarian, prostate, thyroid, and Hodgkin’s disease. It exerts a robust anti-cancer effect and damages healthy tissues throughout the body resulting in cardiotoxicity, hepatotoxicity, and nephrotoxicity  for 4 weeks in Sprague–Dawley rats triggered oxidative stress evidenced by increased lipid peroxidation and reduced glutathione levels. Treatment with DOX also resulted in enhanced NF-κb (p65) (nuclear factor kappa-light-chain-enhancer of activated B cells) nuclear translocation factor, pro-inflammatory cytokine (COX-II/TNF-α) levels, and glial fibrillary acid protein (GFAP), which finally resulted in neuroinflammation. CICI is mainly mediated through oxidative stress by TNF-α elevation, which is reported to inhibit LTP in the hippocampus and dentate gyrus   for once in 5 days for 50 days  for 8 weeks, showed elevated levels of stress-related inflammatory proteins TNF-α, iNOS (inducible nitric oxide synthase) and COX-2 (cyclooxygenase-2)  for 4 weeks and resulted in cognitive deficits accompanied by a decrease in the levels of BDNF and TrKB (tropomyosin-related kinase-B)  in mice showed a decreased clearance of glutamate in the frontal cortex and dentate gyrus assessed 24-h post-injection by employing novel glutamate-selective microelectrode arrays  . It may lead to the opening of mitochondrial permeability transition pores (PTP), causing uncontrolled leakage of cellular constituents and resulting in mitochondrial damage (Javadov and Kuznetsov i.p) in the Novel Object Recognition Task (NORT) evidenced by decreased exploration time and discrimination index with the novel object  treated in athymic nude rats for 4 weeks showed impaired performance (reduced freezing behavior) in the contextual fear conditioning task . DOX impaired the animal’s learning capacity before training, which was measured on day 1 and day 7. In the same study, DOX decreased the innate exploratory behavior in rats determined by the number of rearings performed in the Open Field task  for 4 weeks in male Sprague–Dawley rats significantly increased the escape latency when compared to the control group  for 3 weeks preserved learning and memory assessed during fear conditioning task and NORT which showed no significant difference in the percentage of freezing time and novel object preference (exploration time), respectively. This shows the possible resistance of C57BL/6 J mice to some aspects of CICI as observed in some cancer patients  is one of the frequently used chemotherapeutic agents mainly indicated to treat different types of malignant lymphomas like non-Hodgkin and Hodgkin lymphomas, Burkitt lymphoma, lymphocytic lymphoma, and multiple myeloma, which is either used alone or in combination with other chemotherapeutic agents. Apart from this, CPP is used for breast cancer, retinoblastoma, and ovarian adenocarcinomas. In addition to its anti-neoplastic effects, CPP also has immunosuppressant actions to prevent transplant rejections in autoimmune disorders like multiple sclerosis  for once (on the 7th day of the treatment protocol) in male Swiss mice showed elevated levels of inflammatory cytokines such as TNF-α, IL-6, and IL-1β and reduced the level of anti-inflammatory cytokine IL-10 with enhanced expression of NF-κB in the frontal cortex and hippocampus. CPP administration caused significant damage to neuronal architecture and resulted in neuronal degeneration revealed by the histological findings in the hippocampus and frontal cortex. Researchers also reported that CPP-treated group significantly decreased the retention transfer latency in the step-down latency test  administration in male Wistar rats showed a significant elevation in the levels of cerebral and cerebellar malondialdehyde (MDA) contents, nitrites, and hydrogen peroxide generation. Along with this, catalase, superoxide dismutase, and glutathione S transferase levels were reduced in the CPP-treated brain  increased the levels of MDA, hydroperoxides, and conjugated dienes in the mouse (Swiss Albino) brain  for 4 weeks at weekly intervals using a reward-based delayed spatial alternation paradigm with delay values of 1.5,3, 6.1, 12.4, and 25 s over 80 sessions showed a decline in spatial memory at the most extended delay as the mice ages  for every 2 alternate days (4 scheduled doses) showed cognitive deficits when tested in different behavioral paradigms such as Y maze , and Norwegian Tenecteplase Stroke trial test   was administered in mice and showed cognitive deficits in passive avoidance and object recognition task 12 h after injection. They have also reported that CPP subtly decreased the levels of immunohistochemical markers of neurogenesis such as Ki-67 and DCX in the hippocampus, indicating that CPP induced hippocampus-dependent memory dysfunction  is an antimetabolite commonly used in the treatment of colorectal and breast cancers. It blocks the thymidylate synthase enzyme responsible for converting deoxyuridine monophosphate (dUMP) to thymidine monophosphate (dTMP) for the synthesis of the DNA base, thymidine. It mainly acts by the misincorporation of fluoronucleotides in RNA and DNA, thereby interfering with DNA replication and functioning  to understand the effects of chemotherapy in attentional shifting, which is an integral part of executive function. The results showed that 5-FU impaired attentional shifting. Behavioral outcomes were also compared with the extent of dopamine release measured using fast-scan cyclic voltammetry, which showed decreased dopamine release persisted for a week after the second injection  for 12 days in male Lister hooded rats and showed a decrease in DCX and BDNF levels in the hippocampus. Induction of spatial memory deficits was demonstrated by the inability to discriminate the objects placed in the novel and familiar locations in object location task (OLT)  for 2 weeks showed a decrease in freezing time in a context-dependent conditional emotional response test compared with the control group. It confirms the involvement of the hippocampus in the memory impairment produced by 5-FU. They have also reported a decreased level of cell proliferative marker, Ki67, in the subgranular zone of the dentate gyrus  were trained to respond for a reward in the presence of audible tone on day one as a measure of learning and the same performed on day 22 as a measure of memory retention in the absence of tone. The results showed that 5-FU significantly increased the time required to retrieve previously learned behavior  in male hooded Wistar rats showed significant impairments in the episodic memory tested in NORT. Spatial memory deficits were also assessed in the same study using MWM and showed increased escape latency  of 3 injections over 6 months in mice caused significant induction of apoptosis in the subventricular zone of the dentate gyrus in the hippocampus persisted for 14 days. The same study also reported that 5-FU caused delayed changes in OLIG2 (oligodendrocyte transcription factor-2) expression and resulted in the loss of myelin integrity  thrice over 3 weeks showed disadvantageous effects of 5-FU on neurons by reducing spine density and increasing inflammatory cytokines affecting hippocampal learning and memory. This was confirmed by the decrease in the density of mushroom spines in the dentate gyrus and the overall reduction in spine density in CA1 apical pyramidal dendrites and CA3 apical neurons. The levels of interleukins like IL-17, IL-1β, and GMCSF (granulocyte–macrophage colony-stimulating factor) were also increased in the hippocampus  is an antifolate inhibitor of dihydrofolate reductase (DHFR) employed in the treatment of children with acute lymphoblastic anemia (ALL), non-Hodgkin’s lymphoma, and osteosarcoma. DHFR is involved in converting dihydrofolate (DHF) to tetrahydrofolate (THF), which is needed for purine biosynthesis and acts as the precursor for dTMP synthesis. So, MTX acts as a competitive inhibitor of DHF and interferes in purine and pyrimidine biosynthesis, resulting in cytotoxicity  caused long-term cognitive dysfunction in rats  in male Wistar rats for 7 days showed increased peroxidation level and reduction in GSH/GSSG ratio in different regions of the brain   reveals that oligodendrocyte precursor cells (OPCs) were depleted in the white matter, which leads to impairments in myelination and disruption in neuroplasticity. MTX induced chronic microglial activation and disruption of glial cell homeostasis. The study has also reported that MTX-treated mice did not differentiate between the novel and familiar objects in NORT  on the 7th and 14th days of 36 days treatment period failed to differentiate the novel and familiar object locations in the OLT. In the NORT, rats could not discern between the novel and familiar objects in the choice trial confirming the CICI  into C57BL/6 mice (21 days old) reported impaired hippocampal-dependent cognition assessed using MWM test showed the decreased ability of mice to find the hidden platform  in male Lister hooded rats, given a week apart. Researchers found that MTX induced spatial memory deficits by showing no preference for either the novel or familiar location in the choice trial of OLT. MTX also decreased the Ki67-positive cells in the subgranular zone of the dentate gyrus , and DCX. This was supported by administering two doses of MTX  and found to increase the endoplasmic stress and induced apoptosis confirmed by the presence of a more significant number of TUNEL-positive cells. In the hippocampus, MTX increased the expression of CHOP (CCAAT/enhancer-binding protein (C/EBP)-homologous protein) and cleaved caspase 12 and decreased the expression of DCX- and Ki67-positive neurons in the dentate gyrus. Spatial memory impairments were assessed in the same study using MWM, where the rats with MTX showed a significant decrease in the time spent in the target quadrant compared to the vehicle-treated group  induced changes in hippocampal neurogenesis and behavioral parameters shown by memory deficits in NORT and OLT shown by decrease in preference index as well as decline in neurogenesis markers like Ki67-, BrdU-, and DCX-positive cells  and chronic  administration of MTX in long Evans rats produced spatial memory deficits in OLT and NORT and showed a significant reduction in the serum and CSF folate concentrations  injection showed folate depletion concurred with increased CSF tau and reduced hippocampal cell proliferation  is a platinum-based, broad-spectrum chemotherapeutic drug used in different types of malignancies . The cytotoxic action of CDDP is through its interaction with N7 reactive center on purine residue of DNA to form DNA adducts by intra-strand cross-linkage and activate different downstream signaling pathways  thereby blocking cell division and culminating in apoptosis Siddik .CDDP crosses BBB via copper uptake protein copper transporter (CTR1), which is expressed in the endothelial cells of BBB Kilari  and repoi.p) for 5 days injection-5 days no injection-5 days injection showed loss of arborization and lateral fibers in the cingulate cortex. CDDP increased the translocation of p53 to mitochondria suggesting neuronal mitochondrial damage  administration for 7 weeks in male Wistar rats depicted increased levels of MDA and nitrites, and reduced levels of SOD (superoxide dismutase), and reduced glutathione and catalase in the hippocampus. CDDP treatment increased the levels of different pro-inflammatory cytokines like IL-1β and TNF-α and reduced BDNF levels. It has also enhanced hippocampal NF-κB and reduced expressions of Nrf-2 (nuclear factor erythroid 2-related factor-2) and HO1 (heme oxygenase-1). Behavioral studies showed that CDDP-treated rats spent less time in the target quadrant than the control group in MWM for spatial memory assessment and showed low preference for the novel object in NORT to assess the recognition memory  for 4 weeks in male Sprague–Dawley rats showed less time in freezing in context fear conditioning memory task as well as no preference for either novel or familiar objects in NORT compared with the control group  for 5 days injection-5 days no injection-5 days injection inhibited Akt-mTOR phosphorylation through increased ATF4 (activating transcription factor 4) levels and endoplasmic stress, thereby inducing apoptosis. Cognitive function was assessed using NORT and MWM, where CDDP-treated mice showed impaired episodic and spatial memory, respectively. This was evidenced by the reduced preference for the novel object and increased escape latency compared to the control group  administration for 5 days in Sprague–Dawley rats caused hippocampal-dependent impairment in adult rats  assessed using NORT and fear conditioning memory task  is an analog of CDDP with a 1,2-diamino cyclohexane carrier ligand commonly used in adjuvant and metastatic cancers (Alcindor and Beauger i.p) on cognitive function was assessed in the male hooded Wistar rats at 11 months after treatment reported impairment in recognition memory rats showed by no novel object or location preference in NORT and OLT, respectively  administration in male Wistar rats for 5 consecutive days/week for 2 weeks induced the loss of hippocampal volume estimated by stereology in Cavalieri’s method  for 5 days in male Sprague–Dawley rats accompanied by synaptic dysfunction. This was evidenced by decreased recognition index by OX-treated rats in NORT and showed a deficiency in Mgi.p) 4 times a week showed a rise in MDA and protein carbonyl levels and significant glutathione depletion in the brain mitochondria. In addition, OX treatment caused activation of caspase 3 and inactivation of Bcl-2 with a higher concentration of cytosolic cytochrome c and lower mitochondrial cytochrome c concentration showing neurotoxicity and mitochondrial dysfunction in rats  is a second-generation, semi-synthetic taxane, an antimitotic, chemotherapeutic agent, with multiple effector targets and is widely employed for treating breast, head, neck, prostate, ovarian, and non-small cell lung cancers (Herbst and Khuri i.p) weekly on days 0, 9, 18, and 28 and single intraperitoneal injection of DTX delivery system, which continuously released 8 mg/kg for 4 weeks, in male CD1 mice exhibited significant cognitive impairment in NORT. In MWM, DTX-treated rats reported a reduction in the time spent in the target quadrant but not significantly compared with the control group  in male Sprague–Dawley rats increased the levels of MDA, p38α, MAPK, TNF-α, GFAP, and NF-κB and decreased the levels of glutathione, SOD, catalase, Nrf-2, NCAM , and HO1  for 4 weeks and assessed in object exploration task. DTX treatment reduced exploration of the removed object compared to the control animals  for 3 weeks and short-term treatment as a single injection  in male hooded Wistar rats assessed cognitive impairments in behavioral paradigms like NORT and MWM. Researchers have found that DTX treatment showed impaired cognitive performance in both tasks, but no effect was observed in MWM after acute treatment  in C57BL/6 J mice showed impairments in OLT and simple chronic reaction time task (SCRTT), affecting hippocampal short-term memory and attentional performance, respectively  is another taxane-based chemotherapeutic agent used in breast, ovary, and lung cancers. Cytotoxic action of PTX is by reorganizing the microtubule cytoskeleton and thereby blocking the G2/M phase of the cell cycle, failing mitotic apparatus formation Horwitz . Positroi.p) treatment for 4 days showed impaired spatial memory function with increased duration of escape latency compared with vehicle in MWM test. PTX-induced neuronal apoptosis in the hippocampus was evident through the increased number of TUNEL-positive cells. The study also reported an increase in the expression of proinflammatory cytokines TNF-α and IL-β in the hippocampus  for 4 weeks impaired spatial memory in the MWM task where the animals showed difficulty in finding the location of the escape platform during the acquisition trial and also spent less time in the target quadrant in the probe trial  for 7 days and chronic  for 30 days in male C57BL/6 mice showed decreased testicular zinc levels and reduced expression of ZnT3 in the mossy fibers of the hippocampus. PTX treatment also induced spatial memory deficits in the MWM. This cognitive dysfunction was reversed by supplementing zinc with ZnCl2, increasing zinc levels and neuroblast production  on 4 alternating days reduced the number of Ki67- and BrdU-positive cells in the subgranular zone, indicating hippocampal neurogenesis  is an alkylating agent and an FDA-approved drug for treating glioblastoma multiforme. It exerts cytotoxicity by converting intracellularly to MTIC . This potent methylating agent introduces methyl groups to DNA guanine bases and makes the cellular repair mechanisms unable to correct the methylated bases, followed by the formation of DNA nicks and finally apoptosis  once in 5 days over 32 days showed no preference to the novel object in NORT. The antioxidant analysis showed that TMZ increased MDA and reduced SOD and catalase levels compared with the control group animals  in a cyclic manner for several weeks in male Sprague–Dawley rats impaired hippocampal neurogenesis and endogenous theta activity, which affected learning and memory. Along with this, researchers reported that rats treated with TMZ found difficulty in learning the association between two stimuli if a time gap separates them. Nevertheless, behaviors learned before exposure to TMZ were intact, implying that deficits are more associated with real-time learning aspects than memory  is an FDA-approved treatment to manage metastatic insulinomas in humans. It exerts diabetogenic action in animals to which humans are resistant. In addition, it has nitrosourea-like cytotoxic activity causing DNA alkylation and inhibition of DNA synthesis. But it is not an effective myelosuppressive agent for human insulinomas that do not express the GLUT2 transporters , MTX , and 5-FU  for 4 weeks, reported a decrease in the number of mushroom spines in the dentate gyrus. Impairment in long-term memory was also observed in Y-maze and MWM tasks , MTX , and 5-FU  for 4 weeks showed decreased hippocampal proliferation evidenced by a decrease in the number of BrdU-labeled cells in the dentate gyrus of the hippocampus. Spatial memory deficit was also observed in the MWM task shown by a reduction in path length (Briones and Woods i.p), MTX , 5-FU  for 3 weeks showed impairment in spatial memory, which was evidenced by a decrease in the retention time and increase in the escape latency assessed using MWM task  and DOX  for 3 weeks exhibited decreased freezing behavior in contextual fear conditioning task, which indicates a specific deficit in hippocampal-dependent learning and memory  and CPP  for 4 weeks showed a decreased density of stubby spines in the dentate gyrus of hippocampus exhibiting memory deficits  followed by CPP  for 4 weeks, exhibited spatial memory deficits in the MWM task shown by a decrease in the percentage of entries to the target zone  and DOX  in ovariectomized female Sprague–Dawley rats for 4 weeks showed higher levels of TNF-α, GM-CSF, VEGF, and NF-κb in the hippocampus  and DOX  for 4 weeks could not discriminate between novel and familiar spatial location in novel location recognition task (decrease in exploration time with novel location). Also, spontaneous alternation task was impaired in chemo-treated group in Y-maze test  and 5-FU  for 4 weeks showed spatial memory deficits (spent less time in the target zone) in MWM, and there was an increased tendency to make errors assessed by DNMTS task (delayed matching to sample task)  and 5-FU for 3 weeks produced acquisition and retention deficits in an autoshaping procedure. Here animals were trained to acquire nose-poke response synchronized with tone to receive food as the reward , Adriamycin , CPP  at 2 days interval in 1 week reported impairment in spatial memory shown by increased escape latency and reduced frequency of entry to the target quadrant. Higher levels of TNF-α and IL-6 and decreasing levels of IL-4 and IL-10 in the hippocampus were also reported as a result of chemotherapy  and 5-FU  showed a lower preference for the novel object in NORT. The treatment also impaired contextual fear memory recall (reduced freezing behavior) in fear conditioning task  is one of the commonly employed models for inducing mammary carcinoma in rodents. It directly alkylates DNA and is regarded as the simplest method to offer the characteristics of human mammary carcinoma  followed by DOX  treatment impaired episodic and spatial memory functions in NORT and MWM. DOX treatment was started after confirming mammary carcinoma development, which took around 8–10 weeks and injected once every 5 days over 50 days. DOX-treated NMU rats showed a significant reduction in the recognition index (RI) and discriminative index (DI) in NORT, and decreased the time spent in the target quadrant with increased escape latency compared to the tumor control animals. There was also a significant decrease in the levels of antioxidant enzymes like catalase and SOD and an increase in the levels of proinflammatory cytokine TNF-α in the frontal cortex and hippocampus of NMU + DOX rats. According to the study, an overall tumor-only effect was lacking in contributing to the cognitive deficits that were found to be mainly attributed to the chemotherapy  administration. Hippocampal cell proliferation was assessed by quantifying Ki67-positive cells where the reduction was significant in the Hepatoma + MTX group compared to the hepatoma alone group. This points out that the presence of the tumor did not amplify the harmful effects of MTX on cell proliferation in the hippocampus  into the right flanks to initiate tumor growth. After 1 week of inoculation, MTX  was administered, followed by the behavioral and immunohistochemical analysis. MTX + FM3A animals showed a significant reduction in the cross-over latency compared with the tumor alone group in the passive avoidance test. Apart from this, increased levels of microglia marker Iba1  and proinflammatory markers iNOS and COX-II were found in the FM3A + MTX-treated group  between the shoulder blades, followed by MTX  administration. In neurocognitive assessment using NORT, rats could differentiate the novel and familiar objects before the chemotherapy regimen. But post-chemotherapy impaired the ability to discriminate both objects, implying dyscognition  into the right flank of the mice, followed by the administration of a single intravenous injection of DOX (5 mg/kg) + CPP (10 mg/kg). H&E staining and immunohistochemistry analysis showed decreased DCX-positive cell expression compared to tumor control, which signifies the neural plasticity impairments in the chemotherapy-treated tumor mice  mouse xenograft model. Female athymic nude mice were subcutaneously injected with MDA-MB-231 cells  were subcutaneously injected with the fresh specimen of the tumor (TumorGraft™) into the flanks, followed by the treatment with DOX/PTX/CPP. The results showed the deregulation of different miRNA families, especially miR-200 and miR-183/96/182 clusters in tumor-bearing and chemotherapy-treated animals  in increasing the risk of Alzheimer’s disease  + DOX  + CPP  with 2 days interval and within 1 week showed a significant increase in dendritic spine elimination rate and loss of spine in the cortical neurons compared with the controls using transcranial two-photon imaging techniques. In addition, there was a substantial increase in the level of cytokines like TNF-α and 1L-6 in the frontal cortex and hippocampus  + 5-FU  for 3 weeks. Animals subjected to tumor + chemotherapy showed impairment in hippocampal-dependent spatial memory in MWM and frontal cortex-dependent cued memory in the conditional associative learning task and working memory in the NMTS learning task compared to the tumor alone group. The study reported that transgenic mice without chemotherapy also exhibited impaired learning effects but not as prominent as that of animals with tumor + chemotherapy. Chemotherapy-treated tumor-bearing mice showed cytokine deregulation explained by increased levels of IL-6, TNF-α, RANTES , and impaired neurogenesis indicated by the decreased number of DCX positive neurons  202 Mul/J mouse is an established transgenic model for breast cancer and is slow processing, exhibiting similarities in tumor transformation in humans. MMTV-neu oncogenic mice were treated with MTX  showed improvement in verbal memory aspects  in female breast cancer survivors 1–5 years following chemotherapy but not in other cognitive measures (Lawrence et al.Apart from CNS, chemotherapeutic agents can affect different organ systems and induce several neurological complications. These are manifested in various ways such as neuropathy, encephalopathy, seizures, cerebellar dysfunction, headache, and vision changes (Stone and DeAngelis Most of the chemotherapeutic drugs are processed through the liver (Ramadori and Cameron Each drug used in cancer therapy is anticipated to exert a wide range of biological effects and even gets further complicated when used in combination with other drugs which is reflected in the state of chemobrain. Variability in genetic elements and treatment regimens are few among different factors contributing to the heterogeneity in the pathophysiological conditions of chemobrain. So, focusing on molecular mechanisms of each chemotherapeutic agent can be aimed to modify chemobrain through a targeted approach, which may reduce the toxicities of chemotherapeutics. Animal models covering the full spectrum of the disease are practically impossible but can be employed to test different hypotheses on each pathophysiological state. CICI in healthy animals serves as an initial phase of the study to see the extent of alterations in biochemical and behavioral states caused by individual drugs and the combination of different chemotherapy drugs. Chemobrain induction in tumor-bearing animals gives a clearer picture of the condition in the presence of cancer or after the recovery period. This further provides the evaluation of different pharmacological agents for improving cognitive function without compromising the anti-cancer potential of chemotherapeutics. So, co-administration of chemotherapeutic agents with the protective element can be evaluated extensively in preclinical studies. Because the translational approaches involving these studies should be addressed cautiously since their potential interference could adversely affect the therapeutic efficacy of chemotherapeutic agents. Identifying and determining anatomical regions and biomarkers involved in the cognitive pathway of chemobrain and developing better animal models that can manifest the complexities of disease conditions are necessary to develop new therapeutic strategies to combat CICI.


Ward rounds are sometimes the only opportunity for patients to discuss medication. Patient and professional feedback on an acute male inpatient ward in South London highlighted a demand for more medication information outside the formal ward round setting. We aimed to have 100% of patients meet our criteria for “Patient-Centred Prescribing” on the ward by March 2021. To fulfil criteria, all patients are offered: (1) ward round discussion, (2) written patient information leaflets (PILs), (3) informal discussion groups, all regarding medication.The principles of this quality improvement project (QIP) were drawn from definitions of patient-centred care and standards of good practice; patients should have access to a variety of information formats, relevant to the individual, and the knowledge gained empowers patients.Patient experience data revealed that 30% of clients answered passively to the question, “Do you feel involved in your care?” We hypothesized that medication discussion groups positively impact patients’ wellbeing, by providing a safe space that facilitates conversation surrounding medication issues.We conducted weekly audits on patients whose admission duration was >7 days, and recorded fulfilment of the above criteria. At week 1, we introduced a program of weekly medication discussion groups led by members of the wider multi-disciplinary team covering a broad topic range. At week 6, we developed a rolling rota of the discussion groups and posters were displayed in advance. At week 14, all patients were offered PILs through a 1:1 interaction and this continued as routine practice. Medication discussion group feedback was obtained via questionnaires and “The Blob Tree”, a psycho-emotional assessment tool commonly used in healthcare settings.In 19 weeks, the median percentage of patients who fulfilled our criteria for Patient-Centred Prescribing was 92.86%. After 11 medication discussion groups, 79.3% of questionnaire responders wanted further sessions. 88% of “The Blob Tree” responses collected inferred a positive emotional response after the group discussions and half of those noticed an improvement in their emotional state.This QIP was overall a success; it fulfilled a requirement to meet good standards in information sharing and became embedded in the fabric of the ward, continuing to run as part of the activities program. It demonstrated the impact of education on patients’ mental wellbeing through empowerment and peer support. As a by-product it established multidisciplinary connections and improved therapeutic relationships. Challenges included patient engagement secondary to acute mental illness or negative symptoms and maintaining project momentum following a COVID-19 outbreak.


Mental disorders have high prevalence, but the efficacy of existing therapeutics is limited, in part, because the pathogenic mechanisms remain enigmatic. Current models of neural circuitry include animal models and post-mortem brain tissue, which have allowed enormous progress in understanding the pathophysiology of mental disorders. However, these models limit the ability to assess the functional alterations in short-range and long-range network connectivity between brain regions that are implicated in many mental disorders, e.g., schizophrenia and autism spectrum disorders. This work addresses these limitations by developing an in vitro model of the human brain that models the in vivo cerebral tract environment. In this study, microfabrication and stem cell differentiation techniques were combined to develop an in vitro cerebral tract model that anchors human induced pluripotent stem cell-derived cerebral organoids (COs) and provides a scaffold to promote the formation of a functional connecting neuronal tract. Two designs of a Cerebral Organoid Connectivity Apparatus (COCA) were fabricated using SU-8 photoresist. The first design contains a series of spikes which anchor the CO to the COCA (spiked design), whereas the second design contains flat supporting structures with open holes in a grid pattern to anchor the organoids (grid design); both designs allow effective media exchange. Morphological and functional analyses reveal the expression of key neuronal markers as well as functional activity and signal propagation along cerebral tracts connecting CO pairs. The reported in vitro models enable the investigation of critical neural circuitry involved in neurodevelopmental processes and has the potential to help devise personalized and targeted therapeutic strategies. Mental disorders are the leading cause of disability and the second leading cause of death worldwide ,2. The gMicrofabrication has emerged as a promising tool for the fabrication of compartmentalized in vitro brain-on-a-chip (BoC) systems of human neurocircuitry, where microchannel arrays segregate single axons from neuronal cell bodies. Several groups have reported the fabrication of compartmentalized two-dimensional (2D) cell culture platforms in modeling functional neural circuits and their utility in studying neuronal communication deficits ,11,12,13Cerebral organoids (COs) derived from hiPSCs have emerged as a promising tool for modeling functional 3D human neural tissue. COs spontaneously self-assemble and mature into a 3D neural architecture , providiTo further improve on these technologies, this research focuses on the development of a model system composed of SU-8 photoresist structures designed to anchor COs at a defined distance and promote the formation of an inter-organoid cerebral tract, termed the Cerebral Organoid Connectivity Apparatus (COCA). This report details the fabrication and utility of two COCA versions to accommodate the foremost CO study paradigms: the first design contains a series of spikes in the CO-anchoring area which secure the organoid (spiked COCA), while the second design contains supporting structures onto which COs are attached (grid COCA). These designs also allow effective media exchange around the CO surface. Both designs contain two regions for attaching COs separated by a scaffold track which promotes axonal extension between both sides to create a cerebral tract. The COCA is also accessible and amenable to live-track imaging and electrophysiological characterization. In this work, COCA systems were used to evaluate the morphology and functional intracellular signaling of CO cultures and connecting tracts using fluorescent microscopy, calcium imaging, and viral tracing techniques. Results illustrate the formation of bidirectional long-range neuronal tracts between CO cultures and functional signaling dynamics within CO bodies and along the connecting tracts, demonstrating the potential of this system to model human neurocircuitry and advance treatment development for disorders associated with disrupted neural tract connectivity.The COCA design centers on compartmentalizing CO pairs and forming functional neuronal connections between each side to mimic in vivo cerebral tract circuitry. Two COCA versions were developed: the spiked COCA design features spiked structures in each ring-shaped compartment which anchor the COs in place, and a connecting channel which joins the two compartments to enable neurite extension; the grid COCA design features an open grid structure which permits media flow along the CO surface to improve nutrient diffusion and prolong long-term viability. The devices and fluidic culturing platform were fabricated using long-wave UV (LWUV) light photolithography of SU-8 photoresist and soft lithography techniques, respectively.Both the spiked and grid COCA devices were designed using AutoCAD modeling software  and printed as transparency masks for photolithography . A robust lift-off protocol was developed to release the SU-8 photoresist COCA structures from silicon wafers . SU-8 isCOs were generated using published protocols ,18,28,29After CO generation, they were fixed, sectioned, and processed for immunofluorescence staining using previously reported protocols B,C 29,3,31,32. B2 incubator for 2 h. The COCA was transferred into a dish containing ND medium and COs. COs were carefully embedded on the spikes in the spiked COCA to hold them firmly in place  and incubated at 37 °C in a humidified COin place A. For thing flow D–F. Imag2 while the peristaltic pump was placed a short distance outside of the incubator. The inlet and outlet tubing spanned between the inside and outside of the incubator to permit/establish a closed loop of recirculating flow (A perfusion chamber for CO culturing was fabricated using soft lithography techniques. A 3D printed block (75 mm × 12.5 mm × 15 mm) was placed in the center of a tissue culture plastic dish (100 mm × 15 mm). A polydimethylsiloxane (PDMS) mixture at a 1:10 ratio of elastomeric agent and elastomeric base  was poured into the dish to a height of approximately 10 mm and desiccated for 15 min until all bubbles were removed. The PDMS was cured at 60 °C for at least 1 h before removing the block. An inlet and outlet were drilled on either side of the dish and PDMS using a 1/8” drill bit. The inlet and outlet of the chamber were connected to Tygon silicone tubing  and the tubing was connected to a peristaltic pump . A polylactic acid stand was 3D printed using an Ultimaker 3  and placed in the center of the chamber. Either the spiked or grid COCA device was placed on the stand via the support tabs and held in suspension in order to allow media to flow along all sides of the tissue. Prior to cell culturing, the PDMS chamber in the dish was sterilized under UV light in a culture hood. The PDMS chamber and tubing were washed thrice with both 70% ethanol and Dulbecco’s Phosphate Buffered Saline . The PDMS chamber filled with solution was maintained inside of an incubator at 37 °C and 5% COing flow E,F.After 2 days in static culture, the COCA was transferred to the perfusion chamber. Before COCA placement, the chamber and connected tubing were filled with ND medium. Tubing end caps at either end of the tubing kept the solution contained to avoid spillage and reduce the risk of contamination during transport between the incubator and the culture hood. After transferring the COCA culture to the fluidic platform, the media was perfused using the peristaltic pump at a flow rate of 3 mL/min. Fifty percent of the media was changed every 3–4 days.2PO4, 25 mM NaHCO3, 2.5 mM CaCl2, 1.2 mM MgCl2) pH 7.4 bubbled with 5% CO2, 95% O2. After recording baseline activity, potassium chloride  solution was added to the chamber and the resulting fluorescent intensity was recorded. KCl is known to reliably depolarize neurons, causing a calcium ion influx into functional neurons. Spontaneous and induced electrical activity within each CO on the COCA and along the connecting channel was measured using an Olympus IX81 inverted microscope  and 20× water immersion objective. Time-lapse imaging was performed every 1 s for 5 min and was collected at 512 × 52-pixel resolution. Image analysis was performed using Fiji software (NIH ImageJ). Regions of interest (ROIs) were placed around the soma and/or connecting fiber tracts. Fluorescence was expressed as relative fluorescence changes (∆F/F) after background subtraction from a neighboring region.Calcium imaging was performed on a CO pair (64 DIV) that had been cultured on a spiked COCA for approximately 16 days. Calcium signaling was measured using calcium indicator Fluo-4AM (ThermoFisher Scientific) and imaged at 820 nm using a two-photon microscope . Briefly, the COCA culture was incubated in a loading buffer solution containing Fluo-4AM  and 0.04% Pluronic F-127 at 37 °C for 45 min on an orbital shaker. The COCA culture was then transferred into fresh neuronal differentiation media for at least 30 min before transferring to a submersion-type recording chamber  perfused at room temperature with artificial cerebral spinal fluid solution  or mCherry adeno-associated viruses (AAVs) to distinguish their respective projections and innervations. Lipofectamine 2000 reagent (ThermoFisher Scientific Cat. #STEM00001) in Opti-MEM I Reduced Serum Media was used to transduce the neural progenitor cells at a concentration between 100,000 and 200,000 cells per well of a 24 well-plate. Briefly, 0.75 μg of DNA was diluted in 50 μL OptiMEM and 0.75 μL Lipofectamine 2000 was diluted in 50 μL Opti-MEM. Both volumes were mixed and incubated at room temperature for 5 min. The mixture was added to 100 μL of cell suspension, incubated at room temperature for 1 h, and dispensed into a well. The media was replaced the next day and the culture was visualized for fluorescence using a fluorescent microscope (EVOS).The COCA was fabricated using conventional photolithography techniques. The overall geometry and corresponding dimensions for both spiked and grid COCA versions is shown in COs were generated from human iPSCs following the neural induction culturing protocol outlined in In order to assess functional activity in connected CO pairs (day 64), calcium imaging was performed using a calcium indicator Fluo-4AM. In order to visualize the contribution of individual neurites between COCA compartments, COs were transduced with either mCherry or eGFP adeno-associated viruses (AAVs). After efficient transduction, the CO slices were cultured on adjacent grid COCA compartments for 15 days prior to imaging with fluorescence microscopy A,B. FiguBrain on a Chip (BoC) systems represent a frontier for modeling the brain in a physiologically relevant setting with key clinical applications in disease modeling and pharmacological screening . Herein,Given the importance of preserving in vivo dimensions and structure wherever possible, the connecting COCA channel dimensions separate the CO culturing rings at a distance comparable to the millimeter length scale of in vivo cerebral tracts  33,34].,34.33,34The COCA can be readily integrated with biomedical research since the organoids can be manually placed on the device and cultured in an incubator or microscope stage to gather functional data of cellular morphology, viability, growth dynamics, and electrophysiology. Neuronal lineage of generated COs was confirmed via immunostaining and further characterized via visualization of cellular morphology on the devices. Culturing CO bodies or slices on the spiked or grid COCA, respectively, demonstrated extensive neurite growth along the channel and morphological innervation between CO pairs . TransduOver the past few years, multiple protocols for generating COs have been published ,37,38,39While spiked COCAs adequately secured CO bodies in place, it must be noted that the nature of anchoring the COs onto the compartments may produce unwanted tissue damage in those immediate areas. While overall handling of the cultures and incorporation of COs onto the spiked COCA are performed as gently as possible, the placement may elicit a stress response in the surrounding cell population which could adversely affect their development, intrinsic signaling pathways, and kinetic behavior. The grid COCA circumvents this issue since the tissues are instead gently placed on top. While the open grid structure enables media penetration from beneath the scaffold, areas directly in contact with the grid lines remain inaccessible to the media directly. However, due to the relatively small width of the grid lines in comparison to the overall CO size, it is assumed that the diffusion of media from the open tissue segments is sufficient. Lastly, an important consideration for 3D cultures is to maintain an open platform to permit unconstrained growth space for CO expansion around the device. Constructing organoid models using this key design parameter in addition to a nutrient delivery system to sustain tissue viability will allow researchers to scale up their models and reliably study complex interactions in neural circuitry in vitro.The reported COCA is microfabricated using standard photolithography materials and processing. As such, device features on transparency masks for LWUV light exposure can be adapted as needed for specific applications. The COCA can be adapted to model specific neural circuits heavily involved in neurodevelopmental processes. The ability to pattern COs into specific lineages, such as thalamic, ventral, and cortical brain regions, makes this a promising application to study a critical circuit in isolation while maintaining relevant physiological cues ,23,24. TThis work combines microfabrication and human iPSC cell culture techniques to describe the fabrication and utility of in vitro culturing platforms to model three-dimensional reciprocal neuronal circuits formed between brain organoids. The scaffold was fabricated using SU-8 photoresist patterning and lift-off strategies with a suspended device design that facilitates increased nutrient delivery around the tissue to combat diffusion limit issues native to in vitro CO cultures. CO bodies or slices can be effectively cultured on the SU-8 scaffold to enable reciprocal tract formation and characterized using common morphological and functional analysis techniques. This work provides a proof-of-concept platform for studying circuitry-based dysfunction in human mental disorders. The use of the described COCA systems has the potential to advance research and development of targeted, patient-specific therapeutic strategies against mental disorders associated with abnormal brain structure and function.


Central to this development was the remarkable evolution ofthe catalysts during the past decades. Molybdenum alkylidynes carrying silanolate ligands currently set the standards; their functionalgroup compatibility is exceptional, even though they comprise an earlytransition metal in its highest oxidation state. Their performanceis manifested in case studies in the realm of dynamic covalent chemistry,advanced applications to solid-phase synthesis, a revival of transannularreactions, and the assembly of complex target molecules at sites,which one may not intuitively trace back to an acetylenic ancestor.In parallel with these innovations in material science and organicsynthesis, new insights into the mode of action of the most advancedcatalysts were gained by computational means and the use of unconventionalanalytical tools such as  It is hence hardly surprising that this methodapplies to robust substrates only and its functional group compatibilityis inherently limited. Moreover the active species generated in situdefied direct inspection; therefore, this catalyst system did notlend itself to rational  optimization.The first alkyne metathesis reaction in homogeneous phase usedMo(CO)13 These studies provided compellingevidence for a sequence of [2 + 2] cycloaddition/cycloreversion stepsbeing accountable for the reaction, as had been hypothesized before B.15 Moreover, it became very soon very clear that the proper choiceof ancillary ligands about the active alkylidyne unit is a criticaldeterminant of catalytic activity.13This stunning lack of information on a reasonably popular catalystsystem stood in stark contrast to the very detailed understandingof the organometallic principles. The advent of high-valent transition-metalalkylidyne complexes  laid asolid ground for thorough mechanistic investigations.d before1.14 More1a (R = tBu) (and its close relatives) developed by Schrock and co-workerswas the historically first well-defined alkyne metathesis catalyst.19 The same group also showed that certain molybdenum alkylidynes arecompetent, provided they carry poorer π-donor ligands such as(per)fluorinated tert-alkoxides;21 as the original synthesis of complexes oftype 2 was much less efficient than of their tungstencounterparts, this class of catalysts largely fell into oblivion andwas rediscovered only much later (see below). Finally, rhenium alkylidynessuch as 3 were found to be (moderately) active.24The tungsten alkylidyne complex The catalysts have undergone massive evolution since then; yet,all relevant alkyne metathesis catalysts used to date continue tobe tungsten, molybdenum or rhenium alkylidynes; they are hence variationson the themes originally invented by Schrock in the (early) 1980s.25 one might argue that there is little need foralkyne metathesis in general, not least because most  alkynesare chemically more “expensive” than analogous olefins.Considering the certainly unequal substrate basis only, however, maylead to a distorted picture.For the tremendous success of contemporary olefin metathesis,26 our group was able to demonstrate that evenconformationally unbiased dienes such as 4 cyclize wellwhen treated with the then brand-new first-generation Grubbs catalyst;27 subsequenthydrogenation of product 5 furnished the musk odorantexaltolide in excellent overall yield  was attained with diyne 6 2.40,41 T-alkene 8,43 in hi44 Whatis more, a triple bond offers innumerous possibilities for postmetathetictransformations other than semireduction. It was therefore reasonablefor us to believe at the outset of our project that alkyne metathesiscould serve as a springboard that allows a plethora of structuralmotifs to be attained. The reaction should certainly be consideredas a serious alternative to stereoselective olefin metathesis; atthe same time, however, it might become relevant far beyond this frontieras a valuable synthetic tool in its own right.The ability to set the desired alkene geometry with high fidelityeven at a late stage of a synthesis endeavor is arguably an assetof potentially strategic relevance.7 had shown, the activityof complex 1 was rather modest; warming was necessaryto ensure reasonable rates and the yield of product was not overlyhigh either.40 A much more serious limitationwas the narrow functional group tolerance of 1 and analogues.45 Although a few applications to target-oriented synthesis provedsuccessful,50 substrates as simple as 10–13 wereinadequate likely because the donor sites quench the activity of theLewis-acidic tungsten catalyst and/or get activated and destroyedupon coordination to 1 (41 An attemptto make the anticancer agent epothilone C by RCAM of diyne 18 followed by Lindlar reduction was therefore inconceivable with thetoolbox available before the turn of the millennium (see below).For this vista to become true, however, a number of massive challengeshad to be met. As the formation of ion to 1 2; electrA much improved compatibility of the catalysts with functionalgroups of all sorts hence constituted the single most important goalto be attained at the outset of our venture. To this end, we decidedearly on to defer work on tungsten alkylidynes and redirect our effortstoward molybdenum-based systems for the lower intrinsic Lewis acidityof this transition metal.14 allows the ligand sphere to be adjusted and the catalyticproperties to be fine-tuned. This system found numerous applicationsin polymer chemistry and material science.61On the basis of mechanistic studies which had shown that the Catom of CH14 come at a high “price”: this complex is extremelysensitive and must be prepared and handled with rigorous Schlenk techniques;moreover, it mandates an Ar atmosphere because it is even capableof activating N2 under mild conditions.51 The procedures for its preparation have to be strictlyfollowed since the (redox) chemistry of low-valent molybdenum is intricateand by no means fully understood.62 Likewise,the solvents must be scrupulously dried; the presence of protic sitesin the substrate to be metathesized is inconceivable. The step forwardtaken with 14/CH2Cl2 or complexessuch as 17 in terms of functional group compatibilityhence came along with a step sideward (backward) with regard to handling.The chemical virtues notwithstanding, all catalysts derived from 14/CH2Cl2 is poor, this system provided compelling evidence that alkynemetathesis reactions can be performed in complex settings withoutinterference of common polar and apolar substituents. However, itwas also clear that better access to the relevant catalysts had tobe found without need to resort to 14 as the molybdenumsource.Although the practicality of 1 we conjectured that silanolates might be suitable ancillary ligands.66 They are poorer π-donors than (tertiary) alkoxides;67 moreover, the Si–O–Mo linkageis floppy and hence easy to stretch and bend  metathesis catalysts had been successfully immobilizedon silica surfaces or attached to polyoligomeric silsesquioxanes wasalso deemed encouraging:71 it is the silyloxygroup of the first coordination sphere that basically determines theelectronic structure of the metal center.72 In any case, the reasoning that silanolates might synergize withthe operative molybdenum alkylidyne fragment largely proved correct:in terms of functional group compatibility, silanolate-bearing catalystsbrought alkyne metathesis to a previously unknown level and continueto set the standards in the field.65The adaptive electronic character of a silanolate ligand is arguablyideal in the context of alkyne metathesis.2 to furnishSchrock tribromoalkylidynes such as 20 ;because the uptake of the fourth ligand is reversible, 22 serves as a reservoir for the neutral alkylidyne 23 as the actual catalyst.64 Ate-complex formationis therefore no impediment; in certain cases, the slow release ofthe active species in solution is even beneficial (see below). Ifone so desires, however, this issue can be avoided by resorting to 21 as the substrate: treatment with the silanol of choiceresults in quantitative ligand exchange; no salt is formed and theliberated tert-butanol can simply be removed in vacuo.This procedure is presently our preferred route to the parent complexes 23 as well as to the more modern “canopy catalysts”discussed below.75 In this context, itis also important to mention that the renaissance of molybdenum alkylidynesendowed with partly fluorinated or perfluorinated alkoxide ligands,which the Schrock group had already pioneered but which had then foundlittle echo, was also brought about by the improved access route passingthrough tribromides such as 20.76In parallel, more proficient entries into molybdenum alkyidynecomplexes were established. The currently best way adopts a routeoriginally developed by Mayr and co-workers in which readily accessibleFischer-carbyne complexes are oxidized with Brch as 20 5.73,74 A1a as the classical reference point.64 The reasons for this improved performance are fairly well understood:it has recently been possible, for example, to isolate the metallacyclobutadiene 24 derived from 23 on reaction with excess 3-hexyne.77A → C in 77 It obviously takes very little for 24 to pass through the trigonal-bipyramidal rendition (B) at which the intermediates responsible for productive turn overconverge. These spectroscopic and crystallographic data hence nicelyexplain the excellent reactivity of complex 23 and congeners.The structure of this very sensitive complex in the solid stateis highly instructive 3: it ado64 This practice has been widely embraced.78For a reaction that is inherently reversible, it is necessary toperturb the equilibrium in order to reach quantitative conversion.We showed that addition of molecular sieves is a convenient way todo so, as they are capable of trapping 2-butyne  and henceallow the reaction to proceed to completion even at ambient temperature.23 and relatives.65 A few comments may help to calibratethese results: while the tungsten complex 1 had failedwith substrates carrying even moderately basic N atoms, S-donor sites,or common heterocyclic rings  or electron-deficient substrates,79 whereas 23 does so; this latter aspect proved enabling as witnessed by severaltotal synthesis projects.82 At the meta level, this catalyst can even be compared to the famousruthenium carbene complexes for olefin metathesis, the exquisite toleranceof which is highly appreciated;25 however,Grubbs-type catalysts often fail if the substrates contain amines,sulfides, phosphines. or nitriles. Moreover, phosphine-bearing rutheniumcarbenes endanger azides, alkyl halides, epoxides, and the like.25 When seen against this backdrop, the compatibilityof 23 comprising a non-noble metal atom in its highestoxidation state with all of these functionalities is deemed remarkable.On the other hand, Grubbs-type catalysts truly excel in the presenceof protic groups and remain operative even in aqueous media.25 Although 23 does tolerate certainprotic sites, especially when sterically hindered (see below), thesensitivity toward (moderately) acidic functionality in general remainsthe most eminent Achilles heel.ic rings 2, 23 is 23 and its relatives have an additional bonusin that they form bench-stable adducts with 1,10-phenanthroline or2,2′-bipyridine  to give 26 was fast (<30 min) and high yielding.89 Deprotection of the two −OPMB groupsat C13 and C21 followed by spirocyclization upon activation of thetriple bond with a gold catalyst paved the way to the intricate proteinphosphatase inhibitor spirastrellolide F.89The comparison shown in 27 carryingnothing but an unhindered primary −OH group proved unmanageable:if the alcohol replaces the silanolate ligands in 23,the catalyst gradually or completely loses activity.91In striking contrast, a substrate as simple as 28 and 29, was partly unsuccessfulyet encouraging.92 Partial cross-linkingoccurs on reaction of these conformationally flexible ligands withcomplex 17: the resulting mixture of dimeric/oligomericspecies, however, exhibits excellent catalytic properties. As expected,an improved—though certainly not perfect—compatibilitywith free −OH groups and other protic sites was noticed.92We conjectured that recourse to the chelate effect might help remedythis issue, at least in part, since simultaneous cleavage of threesilanolate linkages is statistically less likely and partial solvolysispotentially reversible. A first foray, which used the readily availabletrisilanoles 30 are sufficientlypreorganized to ligate a single metal center but flexible enough tosupport the different intermediates passed through during a catalyticturnover.93 The preparationof ligands of this type is straightforward, scalable, and modular;the same design was independently pursued by the group of Lee.95Hence, the ligand design was revisited with the hope of formingcatalysts that retain these virtues yet are structurally well-defined.The platform shown in 31 or 32 are indeed privileged catalysts. They combinethe advantages of the parent silanolate-supported molybdenum alkylidynes 23 with a higher robustness against protic substituents includingunprotected alcohols  remains fully operative evenin the presence of two different tertiary amines and a quinoline  carrying lateral methyl substituents is currentlythe most active member of this series,75 although the homologues with higher unbranched alkyl groups retainappreciable reactivity.97 The missing stericprotection, however, renders complex 31 susceptible todegradation by bimolecular coupling,97 whichmay explain why fairly high loadings had to be used in some demandingapplications.For this promising application profile, the canopy catalysts havealready been subject to intense experimental and computational scrutiny.D primarilyformed into a second tautomer from occurring; therefore, the canonicalcourse of alkyne metathesis as shown in The arguably most striking aspect, however, concerns the reactionmechanism itself. The corset of the ligand framework prevents theisomerization of the metallacyclobutadiene 95 it results in exchangeof the R1and R3substituents on the metallacyclicring while maintaining the original tautomeric form; in sodoing, an unprecedented gateway to product formation is opened. Theactual pseudorotation passes through a “bent” metallacyclicintermediate E that can also connect to a metallatetrahedrane G.77 In line with early reasoning,however, G was shown to be an off-cycle intermediate,which could even be isolated in certain settings.94Pseudorotation about the adjacent Mo–O bond allows thishandicap to be circumvented 9:77,95 i98 again, thelatter is off the catalytic cycle and presents a potential doorwayfor catalyst deactivation. The mechanistic similarity to the way thecanopy catalysis operates  character.101A remarkable analogy to observations previously made in the contextof alkene metathesis deserves mentioning. In case of Schrock-typemolybdenum and tungsten alkylidene complexes, the catalytic cyclepasses through a trigonal-bipyramidal metallacyclobutane, which canconvert by turnstile rotation into a square-pyramidal isomer witha bent metallacyclic ring;operates 9 is furt13C NMR data of alkylidynes are informative, especiallywhen the recorded isotropic shift is deconvoluted into the individualcomponents of the shift tensor by computational means.100 Such an analysis allows the energydifferences between filled and empty orbitals (includingthe HOMO/LUMO gap) to be assessed. Complementary information can begained by inspecting the other end of the alkylidyne, that is themolybdenum center. Despite a poor gyromagnetic ratio and low abundance,the spin 5/2 nucleus 95Mo lends itself for this very purpose;103 good spectra were obtained in short acquisition times at slightlyelevated temperatures to slow down quadrupolar relaxation . More quantitative interpretations of the 95Moshifts, however, mandate computational assistance. This is particularlytrue since the electrophilic character of the metal center is stronglygeometry-dependent, most notably on the Mo–O–Si bondangles which modulate the donor strengths of the silanolate ligands(see above). For the floppiness of silanolates, the 95MoNMR shifts in solution necessarily average over many conformations.It will therefore be of interest to record complementary solid state 95Mo NMR data where the dynamic is largely frozen out and aclearer picture of the inherent nature of the different catalystsmight emerge; the experimental challenge, however, is considerable.The resonances of the catalytically active complexes 32 too Lewis acidic  silanolates synergize remarkably well with molybdenumalkylidynes, they proved largely inadequate in the tungsten series.In essence, these poor π-donors render the W(+6) center in complexessuch as s acidic 8. As a c104 Although onemight think of complex 33 as a tethered variant of theclassical Schrock catalyst 1, the constrained ligandgeometry pays valuable dividends. Thus, 33 shows a notablybetter functional group tolerance than 1, although itdoes not rival the best molybdenum canopy catalysts available to date.104Therefore, the ligand design was revisited and the silicon linkerswere replaced altogether.107 the most advanced manifestation features a simple CH group as thecentral linker  complex 36 is an extremely rare case of a non-d0 alkylidyne showing catalytic activity.110 Moreover, 36 is air-stable and tolerates variousgroups that had been problematic in the past: specifically, it isthe only catalyst known to date that works even in the presence ofan unprotected carboxylic acid. Other protic groups including primaryalcohols, phenols, or aniline are equally compatible, as are certaindonor sites.109 Although the reactionscatalyzed by 36 are rather slow and require high temperatures(≥100 °C in toluene), further scrutiny of this lead compoundis warranted.A recent disclosure by Jia and co-workers deserves special emphasisfor two reasons:3 or 37 carrying partly fluorinated or perfluorinatedalkoxide ligands has already been mentioned. A “volcano-type”correlation between the degree of fluorination and catalytic activitywas established, which has to do with the fact that, from a certaindegree of peripheral fluorination onward, the central atoms are tooLewis acidic and the pertinent intermediates on the catalytic cycleoverstabilized.113 Yet other catalyst families are distinguished by heteroleptic ligandspheres, comprising, for example, imidazolin-2-iminato or N-heterocycliccarbenes. Some members of this series such as 38 showimpressive turnover numbers and rates;119 their relevance for advanced synthesis, however, is currently difficultto assess as the set of test substrates is (too) narrow and does notcontain any of the truly challenging functional groups.A myriad of other molybdenum and tungsten alkylidyne complexeswas published during the last decades 10. The r40 denotes the other extreme  ring-opening alkyne metathesis polymerization (ROAMP)in general for the formation of precision polymers was recognizedonly recently;125 it is expected to provide many opportunities for material sciencein the future.126Complex  extreme 11:120 itThis Perspective does not intend to provide a comprehensive coverageof the applications of alkyne metathesis in organic synthesis andmaterial science. Rather, the following examples are solely meantto illustrate aspects of strategic relevance and encourage furtherstudies in this field.127Alkyne metathesis is an inherently reversible process: providedthe chosen catalyst is sufficiently active and long-lived, the reactionis under thermodynamic control. For this reason, it qualifies forapplications to dynamic covalent chemistry (DCC) which mandates thata system is able to correct initial “mistakes” by scramblingof the mixture until the most stable product (distribution) has beenreached. In so doing, DCC provides access to molecular objects beyondreach of more conventional approaches.43,a shape-persistent molecular object of Möbius topology, providesa captivating illustration  alkene metathesis catalyst copes with indiscriminateactivation of all ((Z)-configured) double bonds.RCAM in combination with semireduction allowed the problem to be avoided,and this exceptionally sensitive product to be reached with excellentyield and selectivity  bond.It is important to recognize, however, that alkyne metathesis reachesfar beyond this initial goal in that it also provides an excellentgateway to trisubstituted alkenes. Much of this progress relates tothe fact that propargyl alcohols are compliant and lend themselvesto hydroxy-directed 4 G → H, 14.140−1448 proceeded well with the molybdenumalkylidyne 22  entaileda transannular hydroalkoxylation with formation of the labile enolether 63, which was hydrolyzed upon workup to revealthe peculiar “umpoled” 1,4-oxygenation pattern of amphidinolideF.158The synthesis of spirastrellolide F by RCAM followed by transannularspiroketalization referred to above illustrates this aspect 6.89 No l159 Slow releaseof the active catalyst 23 from the ate-complex 22 gave the best yield of cycloalkyne 66, probablybecause the propargylic acetate in this particular cyclization precursoris exceptionally elimination-prone in the presence of a Lewis acid.Activation of the derived compound 67 with a chiral goldcatalyst caused a 3,3-sigmatropic rearrangement with formation ofallenyl acetate 68, which, once formed, gets activatedby the very same catalyst and succumbs to transannular hydroalkoxylation.Hydrolysis of the resulting enol ester 69 unveils theMichael addition product 70 as immediate precursor ofthe targeted natural product.159An RCAM-based approach to enigmazole plays with the equivalenceof a propargyl acetate and an enone 18.159 Sl160 Once again, it was the tolerance of the molybdenumalkylidyne 23 toward unprotected alcohol and phenol groupsthat proved enabling. Redox isomerization161 of product 72 furnished enone 73 in readinessfor a transannular aza-Michael addition. The ability to encode a 1,3-aminoalcoholmotif in form of an alkyne may not be immediately apparent. Theseexamples showcase that the cornucopia of alkyne metathesis is filledwith a multitude of structural patterns of preparative relevance.Brief reference is also made in this context to lythranidine 19.160 On163 RCAM of diyne 75 with formation of 76 setthe stage for a subsequent π-acid catalyzed annelation of thebenzofuran nucleus (77),164 which was later oxidized to unveil the quinone-methide/lactol chromophoreof this prominent target.The formation of heterocyclic motifs from alkyne precursors hasto be seen in a similar vein. An unconventional approach to the bacterialmetabolite kendomycin represents an elaborate example 20.162,16internal alkynes; methyl caps are by far most common. An expansion of thesubstrate pool in general is highly desirable; terminal alkynes in particular are potentially lucrative starting points.All examples discussed so far relied on the use of 165 the critical step follows the first [2 + 2]cycloaddition in that the resulting complex is prone to transannularC–H insertion with formation of a deprotio-metallacyclobutadiene;this process destroys catalyst and substrate alike. It was much laterthat Tamm and co-workers noticed that Schrock-type molybdenum alkylidynes 3 endowed with poorly basic hexafluoro-tert-butoxide ligands allow this destructive step to be avoided and certainterminal aliphatic alkynes to be metathesized;167 the chosen test set, however, was small.The Schrock group had already uncovered why their use is challenging:23 was found to be equallysuited.168 Upon more comprehensive screening, however,we noticed that this transformation is highly substrate dependentfor reasons that are not entirely clear; a late-stage implementationinto target-oriented synthesis is therefore still deemed (overly)risky.Shortly thereafter, complex one terminal alkyne and one internal alkyneare much better behaved. In this case, RCAM reactions with the aidof 23 and analogues proved robust and high yielding.Our campaign leading to the structure revision of mandelalide A highlightsthis aspect  is all the more surprisingfunctionalized substrates. Finally, the developmentof truly catalytic ways of activating heteroatom-containing triplebonds deserves more attention, as such methods would increase thesubstrate pool to a considerable extent. That the future role of alkynemetathesis will also hinge on the development of ever more effectiveand selective ways of making and manipulating triple bonds is obvious:π-acid catalysis provides an excellent example for how suchconcurrent method development can enlarge the scope;


BDNF) locus on chromosome 11 was the only SNP associated with both smoking and body mass index (BMI) in European, African and Asian population. This study aims to explore the unique genetic predisposition to obesity in former smokers by examining the effects of BDNF on BMI and waist circumference (WC).From genome-wide association studies, brain-derived neurotrophic factor  and central obesity (WC) in 2008–2012. Odds ratios (ORs) and 95% confidence intervals (CIs) for general obesity and central obesity associated with these SNPs were derived from logistic regression.The study design is case-control study with a cohort validation in supplementary. We included 15,072 ethnic Chinese participants in the Guangzhou Biobank Cohort Study (GBCS) with data of four BDNF SNPs (rs4923457 and rs11030104) with both general and central obesity.Of 15,072 participants , 1664 (11.0%) had general and 7868 (52.2%) had central obesity. In 1233 former smokers, the rs6265 GG, versus AA, genotype was associated with higher risks of general obesity  and central obesity  after adjustment. These associations were not significant in never or current smokers. In former heavy (≥20 cigarettes/day) smokers, the rs6265 GG genotype showed a higher odds for general obesity , while no association was found in former light (1–9 cigarettes/day) smokers. Similar results were found for the association of rs6265 with central obesity and for the associations of other two We firstly identified the genetic predisposition (BDNF SNPs) to general and central obesity in former smokers, particularly in former heavy smokers. The different associations of the SNPs for general/central obesity in different smoke exposure groups may be related to the competitive performance of the sites and epigenetic modification, which needs further study.The online version contains supplementary material available at 10.1186/s12864-021-07928-0. Smoking is the leading preventable cause of death worldwide and large scale smoking cessation in the population is urgently needed to reduce the disease burden. However, smoking cessation is often associated with weight gain or even obesity. A large proportion  of smokers do not give up smoking for this reason and some smoke to prevent obesity . HoweverBDNF promotes synaptic remodeling and modulates the function of other neurotransmitters. It also plays a role in the reward response to many drugs, including nicotine [BDNF might be associated with weight gain/obesity related to smoking cessation. Furthermore, previous studies showed that the relationship was not consistent across all levels of BMI and waist circumference (WC), and that central obesity (defined by WC) showed stronger associations with diabetes and cardiovascular disease than general obesity (defined by BMI) [11 and Dutch populations12.Previous genome-wide association studies (GWAS) identified 31 and 97 single nucleotide polymorphisms (SNPs) associated with smoking behavior   . Even thBDNF are the genetic factors of general or central obesity associated with smoking cessation. We used data from the Guangzhou Biobank Cohort Study (GBCS) [We hypothesized that SNPs on y (GBCS) –12 to anDetails of the methods of GBCS have been reported elsewhere –12. BrieInformation on socioeconomic status and lifestyle, including age, sex, education, and tobacco and alcohol use, was collected using a computer-assisted standardized questionnaire administered by trained interviewers. Weight, waist circumference and standing height were measured with light indoor clothing and without shoes by trained nurses of the Guangzhou 12th Hospital.2. General obesity was defined as a BMI ≥ 28 kg/m2 using the criteria for the Asian population [A current smoker was defined as one who, at the time of the survey, smoked one cigarette daily for more than half a year. A former smoker was defined as a person who had smoked daily for at least 6 months during their lifetime but at the time of the survey did not use cigarettes , 14. Cigpulation , 19. Cenpulation . In thisEducational attainment was classified as 0–6 years (primary school or less), 7–12  or ≥ 13 years (university or other tertiary education). Physical activity was measured using the short form of the International Physical Activity Questionnaire , 21. We P > 0·001. Based on the above, we included four candidate SNPs  on BDNF associated with smoking behavior and BMI. Rs6265 and rs11030104 were selected from GWAS for BMI [The inclusion criteria for SNP were as follows: (1) identified by GWAS or meta-analysis published before December 2018; (2) was associated with smoking behavior or BMI; 3) minor allele frequency (MAF) > 0·1 in the HapMap-CHB (Chinese Han Beijing) population; 4) detectable rate > 90% in the participants of the present study; (5) Hardy-Weinberg equilibrium (HWE)  detectab minor al for BMI , and werMoreover, we tested linkage disequilibrium (LD) between the four SNPs using PLINK. As the four SNPs were in a LD region, we also conducted haplotype analysis to confirm the association between the LD region and general/central obesity in former smokers.Plasma aliquots were stored at − 80 °C. DNA was extracted from the whole peripheral blood sample using a standard proteinase K-phenol chloroform method . The labThe SNPs were analyzed by a reputable commercial company in Beijing  using a Mass ARRAY system  . After phttp://www.broadinstitute.org/haploview) and PLINK were used to perform the Hardy-Weinberg equilibrium (HWE) and linkage disequilibrium (LD) tests in the nested case-control study based on the cohort study . IBM SPSS Statistics for Windows, version 19·0  was used for data analysis. The significance level for all tests was set at a two-tailed α value of 0·05. The differences in the proportions across different smoking groups were tested using Chi-square tests  to be the significance level in the Tables P values for trends were calculated in the results of the additive model, and for comparison, the main results were analyzed by additive model again and shown in the supplementary tables (Table 11) were included as covariates in the models. Model A was a crude model, model B was adjusted for age and sex, and model C was adjusted for age, sex, education, income and physical activity. There is such a large difference in smoking rates between men and women in China, so in this study, we first showed the main results in male and female separately in Table HAPLOVIEW software version 4·2  and repeated the analysis. Due to the cultural differences in China, the prevalence of smoking in Chinese women is low. Results of a nationwide representative survey in 2011  showed smoking prevalence of 51.6 and 2.9% in men and women, respectively [For sensitivity and in-depth analysis, we excluded participants with BMI < 18·5 kg/mectively . BecauseThe study was performed in accordance with the ethical standards of the Declaration of Helsinki (1964) and its subsequent amendments. The GBCS was approved by the Medical Ethics Committee of the Chinese PLA General Hospital. All participants provided written informed consent before participating.P < 0·01) but had similar distributions of rs6265, rs4923457, rs11030104, and rs6484320 genotypes (P > 0·05)  were included. At baseline, the average age (± SD) was 62.1 ± 15.4 years. Based on Asia criteria, 6969 participants were classified as overweight, 1664 as generally obese, and 7868 as centrally obese at follow up. There were 12,852 never smokers, 1233 former smokers, and 987 current smokers. These three smoke exposure groups differed in terms of sex, age, education, income, physical activity, central obesity and BMI  before smoking cessation had higher risk of general and central obesity Table . MoreoveThe results were similar for central obesity Fig. . In heav2. The associations of rs6265, rs4923457 and rs11030104 with general obesity in former smokers remained with similar aORs  obesity at baseline and assessed the association with the newly developed general  obesity during follow-up. Because of small sample size, even though the associations between the genotypes of the four SNPs and general obesity were not statistically significant, the patterns were similar Table . Both GGBDNF were associated with general obesity and central obesity in former smokers but not in never and current smokers, which suggests genetic predisposition for obesity associated with smoking cessation. Furthermore, our LD analysis to verify the association of each base combination on general and central obesity showed that the association of SNPs on BDNF in former smokers with general and central obesity varied by cigarette consumption and nicotine dependence before smoking cessation.This study showed that three of the four SNPs on p = 3·5 × 10− 5) than that in former/never female smokers . They concluded that there was limited evidence that smoking status may modify genetic effects of previously identified genetic risk factors for BMI [2) in ever smokers (and the association was significantly stronger in current smokers than former smokers), but no association was observed in never smokers. They concluded that exposure to smoking was causally associated with lower BMI but did not observe attenuation of the associations between genotype and BMI upon adjustment for smoking quantity in the former and current smokers [BDNF were associated with general obesity as well as central obesity in former smokers only, which may indicate a unique genetic mechanism for obesity related to smoking cessation.Even though there has been no previous study that explored the genetic susceptibility loci of obesity related with smoking cessation, previous studies have tested the association between SNPs and BMI by different status of smoke exposure. We searched and found only two related studies. Megan D Fesinmeyer, et al. (25) used Population Architecture using Genomics and Epidemiology (PAGE) data  and 39,716 European Americans (EA)) and tested 10 SNPs selected by genome-wide association studies (GWAS) for BMI or obesity in different smoking exposure groups. However, they combined former smokers and never smokers as one group, so they did not report genetic susceptibility loci of obesity related with smoking cessation. Further, they only adjusted age as a confounder and stratified by racial/ethnic group and sex. They found that rs6548238/TMEM18 C genotype was associated with BMI in AA female nonsmokers (former and never smokers combined) only, and for rs9939609/FTO, the association between A allele and BMI was stronger in current EA female smokers  family, mainly expressed in the hippocampus and cortex. Previous GWAS studies found that SNPs in BDNF were related to tobacco addiction and BMI [BDNF. In former smokers, this addictive behavior indicated by cigarette consumption and nicotine dependence before smoking cessation may be expressed as compensatory overeating which leads to obesity after stopping smoking. There is also evidence that BDNF plays a role in regulation of appetite and result in a phenotype of hyperphagia and obesity [BDNF may be the effective intervention targets of severe obesity after smoking cessation. and BMI . This ma obesity . FurtherOur study had several limitations. First, the most suitable study design to examine the question would have been a prospective study following up a sufficient number of new quitters to examine their subsequent weight gain related to genotypes. However, this is not feasible as all participants of our study were older Chinese and the number of recent quitters was small. We did not have information on changes in BMI/WC in former smokers since smoking cessation. However, when we excluded participants with about the same weight or WC since the age of 18 (i.e. excluding those with weight changed significantly) and former smokers who quit smoking because of disease respectively, the results were similar Table , S23. FuBDNF had an association with general and central obesity in former smokers only, particularly those with heavy cigarette consumption or nicotine dependence before abstinence. These SNPs may be effective intervention targets to prevent obesity after smoking cessation. Our results suggest that heavy smokers with such genetic markers could be at higher risk of obesity after quitting and health care professionals helping them to quit need to pay special attention to this problem.In conclusion, three of the four SNPs on Additional file 1 Table S1–1 The relationship between rs6265, rs11030104 and body mass index (BMI) in the total study sample . Table S1–2 The relationship between rs4923457, rs6484320 and heavy smoking (cigarettes per day ≥ 20) in smokers (N = 2220). Table S1–3 The relationship between the four SNPs and waist circumference by sex in the total study sample . Table S2 Interaction between different SNPs and smoke exposure group. Table S3 Linkage disequilibrium (LD) analysis of the four SNPs’ association with general obesity‡ in former smokers. Table S4 Linkage disequilibrium (LD) analysis of the four SNPs’ association with central obesity‡ in former smokers. Table S5 Association of different smoke exposure groups before cessation with general obesity and central obesity (grouped and continuous variables) in former smokers. Table S6 Association of SNPs with general obesity in different cigarettes per day (CPD) groups before cessation in former smokers. Table S6–1 Association of SNPs with general obesity in different cigarettes per day (CPD) groups before cessation in former smokers (additive model). Table S7 Association of SNPs with general obesity in different Heavy Smoking Index (HSI) score groups before cessation in former smokers. Table S7–1 Association of SNPs with general obesity in different Heavy Smoking Index (HSI) score groups before cessation in former smokers (additive model). Table S8 Association of SNPs with general obesity in different Fagerstrom Test for Nicotine Dependence (FTND) score groups before cessation in former smokers. Table S8–1 Association of SNPs with general obesity in different Fagerstrom Test for Nicotine Dependence (FTND) score groups before cessation in former smokers (additive model). Table S9 Association of SNPs with central obesity in different cigarettes per day (CPD) groups before cessation in former smokers. Table S9–1 Association of SNPs with central obesity in different cigarettes per day (CPD) groups before cessation in former smokers (additive model). Table S10 Association of SNPs with central obesity in different Heavy Smoking Index (HSI) score groups before cessation in former smokers. Table S10–1 Association of SNPs with central obesity in different Heavy Smoking Index (HSI) score groups before cessation in former smokers (additive model). Table S11 Association of SNPs with central obesity in different Fagerstrom Test for Nicotine Dependence (FTND) score groups before cessation in former smokers. Table S11–1 Association of SNPs with central obesity in different Fagerstrom Test for Nicotine Dependence (FTND) score groups before cessation in former smokers (additive model). Table S12 Odds ratios (ORs) (95%CI) of general obesity for different SNPs in different smoke exposure groups (excluding participants with body mass index (BMI) < 18.5 . Table S13 Odds ratios (ORs) (95%CI) of general obesity for different SNPs in former smokers (grouped by years of smoking cessation). Table S14 Relative risks (RRs) (95%CI) of new general obesity for different SNPs in former smokers. Table S15 Odds raios (ORs) (95%CI) of central obesity for different SNPs in former smokers (grouped by years of smoking cessation). Table S16 Relative risks (RRs) (95%CI) of new central obesity for different SNPs in former smokers. Table S17 Odds Ratios (ORs) (95%CI) of general obesity‡ for different SNPs in different smoke exposure groups . Table S18 Odds ratios (ORs) (95%CI) of central obesity‡ for different SNPs in different smoke exposure groups . Table S19 Odds ratios (ORs) (95%CI) of central obesity‡ for different SNPs in different smoke exposure groups . Table S20 Odds ratios (ORs) (95%CI) of general obesity and central obesity‡ for different SNPs in former smokers . Table S21 Characteristics of the participants with or without genetic data. Table S22 Odds ratios (95%CI) of general obesity for different SNPs in different smoke exposure groups (additive model). Table S23 Odds ratios (95%CI) of central obesity for different SNPs in different smoke exposure groups (additive model). S24 The new 8 SNPs both related with smoking behavior and BMI in EBI GWAS Catalog.Additional file 2: Fig. S1 The flow chart of participants.


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