title: Mild hypothermia inhibits exogenous glutamate-induced increases in nitric oxide synthesis.
abstract: The purpose of this study was to investigate changes in nitric oxide (NO) synthesis induced by exogenous glutamate perfusion into the cerebral cortex, and the effects of mild hypothermia on this glutamate-induced NO synthesis. Glutamate-induced cortical lesions were produced by perfusion of 0.5 M glutamate solution via a microdialysis probe, and the extracellular concentrations of NO end-products (nitrite and nitrate) were measured by microdialysis in normothermic (37 degrees C) and hypothermic (32 degrees C) rats. The levels of NO end-products in the normothermia group were elevated markedly by glutamate perfusion, and this change was completely attenuated by the induction of hypothermia. The glutamate-induced increases were also attenuated markedly by both Nomega-nitro-L-arginine methyl ester (L-NAME) and 7-nitroindazole (7-NI). These results suggest that the perfusion of exogenous glutamate into the cortex induces NO synthesis, that is derived primarily from the activity of neuronal NO synthase. These results also demonstrate that hypothermia prevents this glutamate-induced increase in NO, suggesting that the protection afforded by the hypothermic condition is most likely linked to its inhibition of the glutamate-induced NO synthesis.
authors.affiliation: Department of Neurosurgery, Yamaguchi University School of Medicine, Ube, Japan.
authors.forename: Hidehiro
authors.initials: H
authors.lastname: Shima
authors.forename: Hirosuke
authors.initials: H
authors.lastname: Fujisawa
authors.forename: Eiichi
authors.initials: E
authors.lastname: Suehiro
authors.forename: Sinpei
authors.initials: S
authors.lastname: Uetsuka
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Maekawa
authors.forename: Michiyasu
authors.initials: M
authors.lastname: Suzuki
mesh_terms: D000818:Animals; D002540:Cerebral Cortex / Q000187:drug effects* / Q000201:enzymology*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D018698:Glutamic Acid / Q000008:administration & dosage / Q000494:pharmacology*; D007036:Hypothermia, Induced; D007276:Injections, Intraventricular; D008297:Male; D017551:Microdialysis; D009566:Nitrates / Q000032:analysis; D009569:Nitric Oxide / Q000378:metabolism; D019001:Nitric Oxide Synthase / Q000187:drug effects* / Q000378:metabolism; D009573:Nitrites / Q000032:analysis; D051381:Rats; D017208:Rats, Wistar
chemical_list: D004791:Enzyme Inhibitors; D009566:Nitrates; D009573:Nitrites; D009569:Nitric Oxide; D018698:Glutamic Acid; D019001:Nitric Oxide Synthase