Relationship between the gene expression of c-fos and degree of hypoxia in rat brain, as revealed by near-infrared spectroscopy.
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 can be monitored noninvasively. Following reoxygenation after hypoxia, the expression of c-fos and MAP2 mRNAs was determined by reverse transcription-coupled PCR. The expression of MAP2 remained unchanged throughout all conditions from 21 to 8% FiO2. Under the mildly hypoxic 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 lower than 10(-7) M. These data suggest that the decline in oxidative phosphorylation might be a trigger for the induction of c-fos mRNA.
Nomura
Yasutomo
Y
Deptpartment of Bio-System Engineering, Faculty of Engineering, Yamagata University, Yonezawa 992-8510, Japan.
Kinjo
Masataka
M
Tamura
Mamoru
M
D000818:Animals; D001921:Brain / Q000378:metabolism* / Q000503:physiopathology; D016762:Genes, fos; D000860:Hypoxia / Q000235:genetics* / Q000503:physiopathology; D008297:Male; D012333:RNA, Messenger / Q000235:genetics; D051381:Rats; D017208:Rats, Wistar; D020133:Reverse Transcriptase Polymerase Chain Reaction; D019265:Spectroscopy, Near-Infrared / Q000379:methods*
D012333:RNA, Messenger