Regulation of citrate synthase and phosphoenolpyruvate carboxykinase by hydrocortisone in the liver of aging rats.
The activities and hormonal regulations of citrate synthase (CS) and phosphoenolpyruvate carboxykinase (PEPCK) in the liver of male rats of various ages were studied. It has been observed that the activity of CS increases gradually as a function of age of the rat. The activity of PEPCK, on the other hand is highest in the liver of adult rats. Adrenalectomy causes no significant change in the activity of CS of the liver of young, adult and old rats. However, this treatment decreases significantly the activity of PEPCK of the liver of rats of all the ages. Administration of hydrocortisone to adrenalectomized rats depresses and induces, respectively, the activity of CS and PEPCK in the liver of young and adult rats but not in the old rats. This hormone mediated effect of the enzymes decreases with increasing age of the rats. Treatment of actinomycin D prior to hydrocortisone administration tends to normalize the depressed level of CS. However, this inhibitor inhibits the PEPCK induction.
D000311:Adrenal Glands / Q000502:physiology; D000315:Adrenalectomy; D000375:Aging; D000818:Animals; D002950:Citrate (si)-Synthase / Q000378:metabolism*; D003609:Dactinomycin / Q000494:pharmacology; D004790:Enzyme Induction / Q000187:drug effects; D006854:Hydrocortisone / Q000502:physiology*; D008099:Liver / Q000201:enzymology*; D008297:Male; D007652:Oxo-Acid-Lyases / Q000378:metabolism*; D010729:Phosphoenolpyruvate Carboxykinase (GTP) / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains
D003609:Dactinomycin; D002950:Citrate (si)-Synthase; D010729:Phosphoenolpyruvate Carboxykinase (GTP); D007652:Oxo-Acid-Lyases; D006854:Hydrocortisone