c-fos expression and redox state of cytochrome oxidase of rat brain in hypoxia.
Hypoxic induction of c-fos was studied in rat brains as a function of the cerebral oxygenation state using near-infrared spectroscopy by which the hemoglobin oxygenation state and redox state of mitochondrial cytochrome oxidase could be monitored noninvasively. Following reoxygenation after hypoxia, the expression of c-fos and MAP2 mRNAs was followed by reverse transcription-coupled PCR. The expression of MAP2 remained unchanged throughout all the conditions from 21 to 8% FiO2. Under mildly hypoxia conditions, c-fos mRNA was not induced. Hemoglobin was partially deoxygenated but cytochrome oxidase remained fully oxidized. Severe hypoxia, where cytochrome oxidase was reduced, caused a significant induction of c-fos mRNA At this stage, the oxygen concentration in cerebral tissue fell to < 10(-7) M. These data suggest that the decline in oxidative phosphorylation might be a trigger for the induction of c-fos mRNA.
Nomura
Y
Y
Laboratory of Supramolecular Biophysics, Research Institute for Electronic Science, Hokkaido University, Sapporo, Japan.
Kinjo
M
M
Tamura
M
M
D000818:Animals; D001921:Brain / Q000378:metabolism*; D003576:Electron Transport Complex IV / Q000378:metabolism*; D005786:Gene Expression Regulation / Q000502:physiology; D006454:Hemoglobins / Q000378:metabolism; D002534:Hypoxia, Brain / Q000201:enzymology* / Q000378:metabolism; D008297:Male; D010084:Oxidation-Reduction; D016760:Proto-Oncogene Proteins c-fos / Q000096:biosynthesis* / Q000235:genetics; D012333:RNA, Messenger / Q000096:biosynthesis; D051381:Rats; D017208:Rats, Wistar; D019265:Spectroscopy, Near-Infrared; D014158:Transcription, Genetic
D006454:Hemoglobins; D016760:Proto-Oncogene Proteins c-fos; D012333:RNA, Messenger; D003576:Electron Transport Complex IV