Possible intervention of insulin, cyclic AMP, and glucocorticoids in protein-sparing action of dietary carbohydrate in rats.
The present study was carried out to examine the possible intervention of some hormones in the "protein-sparing/actions of dietary carbohydrate and fat. Administration of either a carbohydrate meal or a fat meal to fasted rats caused a reduction in the urinary output of urea and total nitrogen with a concomitant decrease in rate of urogenesis in liver. as well as the activities of some amino acid-catabolizing enzymes in liver. The sparing action of carbohydrate but not that of fat was abolished in alloxan-diabetic rats. Feeding rats a carbohydrate meal caused a marked reduction in the amount of cyclic AMP in liver. The change was coincident with a reduction in the level of plasma urea and the urinary output of urea and total nitorgen. Administration of dibutyryl cyclic AMP abolished the carbohydrate-induced depression of urinary output of urea and total nitrogen as well as partially the activity of serine dehydratase in liver. Feeding a carbohydrate meal resulted in a significant reduction in the level of corticosterone in plasma. However, the possible intervention of glucocorticoids in the protein-sparing action of carbohydrate was ruled out inasmuch as the action of carbohydrate was also observed in the adrenalectomized rats. The overall results suggest that the protein-sparing action of dietary carbohydrate may be exerted in a different fashion from that of fat, that is, through depression of cyclic AMP in liver and thus the reduction of the degradation of amino acids in liver
D000311:Adrenal Glands / Q000502:physiology; D000315:Adrenalectomy; D000818:Animals; D003994:Bucladesine / Q000494:pharmacology; D003345:Corticosterone / Q000097:blood; D000242:Cyclic AMP / Q000378:metabolism / Q000494:pharmacology*; D003921:Diabetes Mellitus, Experimental / Q000378:metabolism*; D004040:Dietary Carbohydrates / Q000008:administration & dosage*; D004794:Enzyme Repression / Q000187:drug effects; D005938:Glucocorticoids / Q000494:pharmacology*; D007328:Insulin / Q000494:pharmacology*; D012695:L-Serine Dehydratase / Q000378:metabolism; D008099:Liver / Q000378:metabolism; D008297:Male; D009132:Muscles / Q000378:metabolism; D009584:Nitrogen / Q000378:metabolism; D011506:Proteins / Q000378:metabolism*; D051381:Rats; D013217:Starvation; D014508:Urea / Q000378:metabolism
D004040:Dietary Carbohydrates; D005938:Glucocorticoids; D007328:Insulin; D011506:Proteins; D003994:Bucladesine; D014508:Urea; D000242:Cyclic AMP; D012695:L-Serine Dehydratase; D009584:Nitrogen; D003345:Corticosterone