Hemoglobin-induced neuronal degeneration in the hippocampus after neonatal intraventricular hemorrhage.
Neuronal degeneration following neonatal intraventricular hemorrhage (IVH) is incompletely understood. Understanding the mechanisms of degeneration and cell loss may point toward specific treatments to limit injury. We evaluated the role of hemoglobin (Hb) in cell death after intraventricular injection in neonatal rats. Hb was injected into the right lateral ventricle of post-natal day 7 rats. Rats exposed to anesthesia were used for controls. The CA-1 region of the hippocampus was analyzed via immunohistochemistry, hematoxylin and eosin (H&E) staining, Fluoro-Jade C staining, Western blots, and double-labeling stains. Compared to controls, intraventricular injection of Hb decreased hippocampal volume (27% decrease; p<0.05), induced neuronal loss (31% loss; p<0.01), and increased neuronal degeneration (2.7 fold increase; p<0.01), which were all significantly reduced with the iron chelator, deferoxamine. Hb upregulated p-JNK (1.8 fold increase; p<0.05) and increased expression of the Hb/haptoglobin endocytotic receptor CD163 in neurons in vivo and in vitro (cultured cortical neurons). Hb induced expression of the CD163 receptor, which co-localized with p-JNK in hippocampal neurons, suggesting a potential pathway by which Hb enters the neuron to result in cell death. There were no differences in neuronal loss or degenerating neurons in Hb-injected animals that developed hydrocephalus versus those that did not. Intraventricular injection of Hb causes hippocampal neuronal degeneration and cell loss and increases brain p-JNK levels. p-JNK co-localized with the Hb/haptoglobin receptor CD163, suggesting a novel pathway by which Hb enters the neuron after IVH to result in cell death.
['Garton|Thomas P|TP|', 'He|Yangdong|Y|', 'Garton|Hugh J L|HJ|', 'Keep|Richard F|RF|', 'Xi|Guohua|G|', 'Strahle|Jennifer M|JM|']
D000818:Animals D000831:Animals, Newborn D015703:Antigens, CD D015214:Antigens, Differentiation, Myelomonocytic D002543:Cerebral Hemorrhage D003676:Deferoxamine D006454:Hemoglobins D006624:Hippocampus D006849:Hydrocephalus D007276:Injections, Intraventricular D048031:JNK Mitogen-Activated Protein Kinases D009474:Neurons D051381:Rats D017207:Rats, Sprague-Dawley D011956:Receptors, Cell Surface
Neuron Hippocampus Intraventricular hemorrhage Hemoglobin Deferoxamine CD163