Expression of nitrergic system and protein nitration in adult rat brains submitted to acute hypobaric hypoxia.
Changes in the nitric oxide (NO) system of the rat cerebral cortex were investigated by immunohistochemistry, immunoblotting, and NO synthase (NOS) activity assays in adult rats submitted for 30 min to hypoxia, in a hypobaric chamber at a simulated altitude of 38,000 ft (11000 m) (154.9 mm Hg). The cerebral cortex was studied after different survival times, 0 and 24 h, 5, 8, 15, and 30 days of reoxygenation. This situation led to morphological alterations in the large type I interneurons, as well as immunoreactive changes in the appearance and number of the small neurons (type II), both containing neuronal NOS (nNOS). Some of these small neurons showed immunoreactive cytoplasm and short processes; others, the more numerous during all reoxygenation periods, contained the immunoreactive product mainly related to a perinuclear ring. Ultrastructurally, these small neurons exhibited changes in nuclear structures as in the shape of the nuclear membrane, in the distribution of heterochromatin, and in the nucleolar morphology. The reaction product for nitrotyrosine, as a marker of protein nitration, showed modifications in distribution of the immunoreactive product. No expression was found for inducible NOS (iNOS). All these modifications were accompanied by increased nNOS and nitrotyrosine production as demonstrated by Western blotting and calcium-dependent activity, returning to control conditions after 30 days of reoxygenation, suggesting a reversible NO mechanism of action.
Castro-Blanco
Susana
S
Department of Neuroanatomy and Cell Biology, Instituto de Neurobiologia Santiago Ramón y Cajal, CSIC, E-28002 Madrid, Spain.
Encinas
Juan Manuel
JM
Serrano
Julia
J
Alonso
David
D
Gómez
María Benita
MB
Sánchez
Jaime
J
Ríos-Tejada
Francisco
F
Fernández-Vizarra
Paula
P
Fernández
Ana Patricia
AP
Martínez-Murillo
Ricardo
R
Rodrigo
José
J
D000818:Animals; D001274:Atmospheric Pressure; D001923:Brain Chemistry; D002540:Cerebral Cortex / Q000098:blood supply / Q000201:enzymology / Q000378:metabolism; D000860:Hypoxia / Q000378:metabolism*; D007150:Immunohistochemistry; D008297:Male; D026602:Nitrergic Neurons / Q000378:metabolism*; D009569:Nitric Oxide / Q000378:metabolism*; D019001:Nitric Oxide Synthase / Q000378:metabolism; D052248:Nitric Oxide Synthase Type I; D052247:Nitric Oxide Synthase Type II; D011506:Proteins / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D014443:Tyrosine / Q000031:analogs & derivatives* / Q000032:analysis
D011506:Proteins; D009569:Nitric Oxide; 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