title: Effect of corticosterone administration at varying levels on leucine oxidation and whole body protein synthesis and breakdown in adrenalectomized rats.
abstract: Adrenalectomized rats were implanted with pellets containing corticosterone in proportions varying from 0% to 100%, plus cholesterol. Stable levels of plasma corticosterone resulted, varying from close to zero (I) to physiologic (II) to supraphysiologic (III). Whole body protein synthesis (S) was measured during fasting by a technique involving injection of [1-14C]-leucine, analysis of expired air for 14CO2, and measurement of urinary excretion of urea N plus ammonia N (C). Whole body breakdown (B) during fasting was calculated as the sum of S and C. C rose progressively from I to III, but fractional oxidation of 14C leucine was lowest in II. Both S and B were markedly reduced in I and maximal in II. In III, S fell but B remained high. Thus variations in glucocorticoid levels above and below physiologic exert profound effects on leucine oxidation and protein turnover, involving effects on both synthesis and breakdown.
authors.affiliation: Department of Pharmacology and Molecular Sciences, Johns Hopkins University, School of Medicine, Baltimore, MD 21205.
authors.forename: Z Y
authors.initials: ZY
authors.lastname: Quan
authors.forename: M
authors.initials: M
authors.lastname: Walser
mesh_terms: D000315:Adrenalectomy; D000818:Animals; D003345:Corticosterone / Q000097:blood / Q000494:pharmacology*; D007930:Leucine / Q000378:metabolism*; D008297:Male; D009584:Nitrogen / Q000652:urine; D010084:Oxidation-Reduction / Q000187:drug effects; D014176:Protein Biosynthesis; D011506:Proteins / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains
chemical_list: D011506:Proteins; D007930:Leucine; D009584:Nitrogen; D003345:Corticosterone