Regulation of NAD- and NADP-linked isocitrate dehydrogenase by hydrocortisone in the brain and liver of male rats of various ages.
The activity and hormonal regulation of NAD- and NADP-linked isocitrate dehydrogenase (EC 1.1.1.41 and 1.1.1.42, respectively) in the brain and liver of rats of various ages were investigated. The activity of NAD-linked isocitrate dehydrogenase of the brain was greater than cytoplasmic or mitochondrial NADP-linked isocitrate dehydrogenase. In contrast, the cytoplasmic NADP-isocitrate dehydrogenase of the liver predominates over both NAD- and mitochondrial NADP-isocitrate dehydrogenases at the three ages studied. The activity of NAD-isocitrate dehydrogenase increased in the brain (139%) and liver (17%) of rats up to 33 weeks of age and decreased (57 and 39%, respectively) in old rats (85-week-old). The activity of cytoplasmic NADP-isocitrate dehydrogenase was maximum in immature (6-week-old) rat brain and decreased as the age of the rats increased; whereas, in liver, the activity of this enzyme was found o be maximum in adult rats (33-week-old). Brain mitochondrial NADP-isocitrate dehydrogenase activity increased (64%) in adult rats, but in liver it decreased (45 and 33% in 33- and 85-week-old rats, respectively). In both tissues, adrenalectomy and hydrocortisone treatment showed differential age-dependent response. Hydrocortisone-mediated induction of the level of enzymes was inhibited by actinomycin D.
D000311:Adrenal Glands / Q000502:physiology; D000367:Age Factors; D000818:Animals; D001921:Brain / Q000201:enzymology*; D003593:Cytoplasm / Q000201:enzymology; D006854:Hydrocortisone / Q000494:pharmacology*; D007521:Isocitrate Dehydrogenase / Q000378:metabolism*; D008099:Liver / Q000201:enzymology*; D008297:Male; D008928:Mitochondria / Q000201:enzymology; D009243:NAD; D009249:NADP; D051381:Rats
D009243:NAD; D009249:NADP; D007521:Isocitrate Dehydrogenase; D006854:Hydrocortisone