Obesity does not aggravate osteoporosis or osteoblastic insulin resistance in orchiectomized rats.
The present study aimed to test the hypothesis that testosterone deprivation impairs osteoblastic insulin signaling, decreases osteoblast survival, reduces bone density, and that obesity aggravates those deleterious effects in testosterone-deprived rats. Twenty four male Wistar rats underwent either a bilateral orchiectomy (O, n=12) or a sham operation (S, n=12). Then the rats in each group were further divided into two subgroups fed with either a normal diet (ND) or a high-fat diet (HF) for 12 weeks. At the end of the protocol, blood samples were collected to determine metabolic parameters and osteocalcin ratios. The tibiae were collected to determine bone mass using microcomputed tomography and for osteoblast isolation. The results showed that rats fed with HF (sham-operated HF-fed rats (HFS) and ORX HF-fed rats (HFO)) developed peripheral insulin resistance and had decreased trabecular bone density. In ND-fed rats, only the ORX ND-fed rats (NDO) group had decreased trabecular bone density. In addition, osteoblastic insulin resistance, as indicated by a decrease in tyrosine phosphorylation of the insulin receptor and Akt, were observed in all groups except the sham-operated ND-fed rats (NDS) rats. Those groups, again with the exception of the NDS rats, also had decreased osteoblastic survival. No differences in the levels of osteoblastic insulin resistance and osteoblastic survival were found among the NDO, HFS, and HFO groups. These findings suggest that either testosterone deprivation or obesity alone can impair osteoblastic insulin signaling and decrease osteoblastic survival leading to the development of osteoporosis. However, obesity does not aggravate those deleterious effects in the bone of testosterone-deprived rats.
['Potikanond|Saranyapin|S|', 'Rattanachote|Pinyada|P|', 'Pintana|Hiranya|H|', 'Suntornsaratoon|Panan|P|', 'Charoenphandhu|Narattaphol|N|', 'Chattipakorn|Nipon|N|', 'Chattipakorn|Siriporn|S|']
D000818:Animals D017209:Apoptosis D015519:Bone Density D049109:Cell Proliferation D002470:Cell Survival D002478:Cells, Cultured D059305:Diet, High-Fat D007333:Insulin Resistance D008297:Male D009765:Obesity D009919:Orchiectomy D010006:Osteoblasts D015675:Osteocalcin D010024:Osteoporosis D051381:Rats D017208:Rats, Wistar D013739:Testosterone
testosterone deprivation osteoblastic insulin signaling high-fat diet induced obesity