title: Nitric oxide system and protein nitration are modified by an acute hypobaric hypoxia in the adult rat hippocampus.
abstract: Changes in the nitric oxide system of the hippocampus from rats submitted to hypobaric hypoxia were investigated. Adult rats were exposed to a simulated altitude of 8,325 m (27,000 ft) for 7 h and killed after 0 h, 1, 3, 5, 10 and 20 days of reoxygenation. The number of neuronal nitric oxide synthase immunoreactive neurons and their dendritic plexus, as well as neuronal nitric oxide synthase immunoblotting densitometry and calcium-dependent activity increased from 0 h to 3 days of reoxygenation. In addition, endothelial nitric oxide synthase immunoreactivity peaked after 7 h of hypobaric hypoxia. Nitrotyrosine immunoreactivity showed an increase in the pyramidal cells of CA2-CA3 and in glial cells surrounding the blood vessels after 0 h, 1 and 3 days of reoxygenation. Immunoblotting densitometry of 1 of the 2 nitrotyrosine-immunoreactive bands detected also increased after 0 h and 1 day of reoxygenation. Inducible nitric oxide synthase immunoreactivity was found only in some blood vessels after 0 h, 1 and 3 days of reoxygenation, but no changes in inducible nitric oxide synthase activity or immunoblotting were detected. We conclude that transient activation of the nitric oxide system constitutes a hippocampal response to hypobaric hypoxia.
mesh_terms: D000818:Animals; D015153:Blotting, Western / Q000379:methods; D002452:Cell Count; D004195:Disease Models, Animal; D004730:Endothelium, Vascular / Q000378:metabolism; D005904:Glial Fibrillary Acidic Protein / Q000378:metabolism; D006624:Hippocampus / Q000166:cytology / Q000378:metabolism*; D000860:Hypoxia / Q000378:metabolism*; D007150:Immunohistochemistry / Q000379:methods; D008297:Male; D009566:Nitrates / Q000378:metabolism*; D019001:Nitric Oxide Synthase / Q000145:classification / Q000378:metabolism*; D052248:Nitric Oxide Synthase Type I; D052247:Nitric Oxide Synthase Type II; D051381:Rats; D017208:Rats, Wistar; D013997:Time Factors; D014443:Tyrosine / Q000031:analogs & derivatives* / Q000378:metabolism*
chemical_list: D005904:Glial Fibrillary Acidic Protein; D009566:Nitrates; C002744:3-nitrotyrosine; D014443:Tyrosine; D019001:Nitric Oxide Synthase; D052248:Nitric Oxide Synthase Type I; D052247:Nitric Oxide Synthase Type II; C496322:Nos1 protein, rat; C496318:Nos2 protein, rat