The effect of testosterone on the synthesis of mouse kidney mitochondrial and microsomal proteins in vivo and in vitro.

Abstract

Castration of 8–week—old male mice resulted in a decrease in kidney wt to a plateau level about 65–70% of normal within 14 days. This wt loss was accompanied by decreases in the rate of incorporation of radioactive amino acids in vivo into mitochondrial and microsomal proteins as well as a decrease in the rate of incorporation of radioactive amino acids into protein by isolated mitochondria in vitro. Rates of incorporation both in vivo and in vitro reached minimal values (60–65% of normal) approximately 8 days after castration and appeared to recover spontaneously, reaching normal or near normal levels by the 3rd week following castration. The rate of degradation of mitochondrial and microsomal proteins isolated from liver and kidney was determined by measuring the rate of disappearance of L—arginine—guanidino–14C radioactivity from the protein of the two fractions. The small changes found in the protein half lives of the two fractions in either organ following castration suggested that the decrease in kidney wt following castration could be attributed primarily, if not entirely, to the decreased synthetic rate. Administration of testosterone to castrate animals during the period of depressed protein synthesis (days 6–14 after castration) resulted in an increase in synthetic rate within 11–18 hr when tested in vitro and within 14 hr when tested in vivo. (Endocrinology91: 125, 1972)