Regulation of NAD- and NADP-linked isocitrate dehydrogenase by thyroxine in the brain and liver of female rats of various ages.
The specific activity of NAD- and NADP-linked isocitrate dehydrogenase and their regulation by thyroxine in the brain and liver of female rats of various ages were studied with the ultimate goal of better understanding the decreased physiological functioning of the brain and liver during old age. Both thyroidectomy and thyroxine treatment have differential age-dependent effects on the activities of these enzymes in both tissues. The activity of NAD-ICDH decreases whereas both cytoplasmic and mitochondrial NADP-ICDH increase simultaneously following thyroidectomy. Thyroxine administration induces NAD-ICDH and depresses NADP-ICDH. The degree of induction and/or repression is lowest in old rats. These effects of thyroxine are actinomycin D sensitive in both the tissues of rats.
D000367:Age Factors; D000818:Animals; D001921:Brain / Q000187:drug effects / Q000201:enzymology*; D005260:Female; D007521:Isocitrate Dehydrogenase / Q000032:analysis* / Q000378:metabolism*; D008099:Liver / Q000187:drug effects / Q000201:enzymology*; D009243:NAD; D009249:NADP; D010101:Oxygen Consumption; D051381:Rats; D011919:Rats, Inbred Strains; D013965:Thyroidectomy; D013974:Thyroxine / Q000494:pharmacology*
D009243:NAD; D009249:NADP; D007521:Isocitrate Dehydrogenase; C039355:isocitrate dehydrogenase (NADP+); D013974:Thyroxine