Effect of long-term hypoxia upon the activity of some enzymes in the brain of rats during early postnatal ontogenesis and in adulthood.
Enzymatic activities were determined in the prosencephalon of rats which had been exposed repeatedly for 8 hrs, either from the age of 1 to 17 days or in adulthood, to an altitude of 7,000 m in a barometric chamber (up to a total of 104 hrs). The activity of enzymes was assayed 20 hrs after the last exposure. The results were compared with values obtained 20 hrs after a single 8-hour exposure to a stimulated altitude of 7,000 m in 17-day-old and adult rats. In young rats a single exposure to hypoxia, the most elevated was the activity of LDH and isoCDH, while GPT and CPK were decreased. After repeated hypoxia, the most significant increasw was noted in the activity of PK and again a decrease in GPT and CPK. In adulthood, a single exposure to hypoxia causes the greatest increase in CPK, while LDH and GOT are reduced. Following repeated hypoxia, none of the enzyme activities were increased by more than 20%, while LDH, GOT, GIDH and CPK were again lower. It is concluded from these results that a single exposure to hypoxia increases anaerobic glycolysis in the immature nervous tissue and improves its oxygen utilization. The relationship between glycid and amino acid metabolism are not appreciably altered. On the other hand, a general reduction of bioenergetics and biosynthesis occurs in adulthood. Repeated hypoxia, on the contrary, has similar after-effects in both age groups, namely inhibition of aerobic metabolism and of the relations between glycid and amino acid metabolism.
D000367:Age Factors; D000410:Alanine Transaminase / Q000378:metabolism; D000818:Animals; D000831:Animals, Newborn / Q000378:metabolism*; D001219:Aspartate Aminotransferases / Q000378:metabolism; D001921:Brain / Q000196:embryology / Q000201:enzymology* / Q000254:growth & development; D003402:Creatine Kinase / Q000378:metabolism; D005260:Female; D000860:Hypoxia / Q000201:enzymology*; D007521:Isocitrate Dehydrogenase / Q000378:metabolism; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D008297:Male; D010088:Oxidoreductases / Q000378:metabolism*; D011770:Pyruvate Kinase / Q000378:metabolism; D051381:Rats; D014166:Transferases / Q000378:metabolism*
D010088:Oxidoreductases; D007770:L-Lactate Dehydrogenase; D007521:Isocitrate Dehydrogenase; D014166:Transferases; D001219:Aspartate Aminotransferases; D000410:Alanine Transaminase; D011770:Pyruvate Kinase; D003402:Creatine Kinase