SEX-DIFFERENCES IN ADRENOCORTICAL STRUCTURE AND FUNCTION .3. EFFECTS OF POSTPUBERTAL GONADECTOMY AND GONADAL HORMONE REPLACEMENT ON ADRENAL CHOLESTEROL SIDECHAIN CLEAVAGE ACTIVITY AND ON STEROIDS BIOSYNTHESIS BY RAT ADRENAL HOMOGENATES

  • 1 January 1976
    • journal article
    • research article
    • Vol. 67  (1) , 26-35
Abstract
In rats postpubertal orchiectomy increases the adrenal weight; testosterone replacement restores the adrenal weight to the normal level. Neither ovariectomy (8 wk of duration) nor estradiol replacement has an effect on adrenal weight in female rats. Pregnenolone synthesis and corticosterone and blue tetrazolium-positive steroids secretion is significantly higher in homogenates of adrenals from female rats than from males. Orchiectomy increases pregnenolone biosynthesis; testosterone replacement restores the value to normal levels. Neither ovariectomy nor estradiol replacement has an effect on pregnenolone synthesis in vitro. In both sexes gonadectomy decreases corticosterone output by adrenal homogenates; concomitantly the increase in the adrenal 5.alpha.-reductase activity is observed. The ratio of secreted corticosterone to pregnenolone is significantly lower in gonadectomized rats of both sexes than in control animals. Estradiol or testosterone replacement inhibits the adrenal 5.alpha.-reductase activity and restores corticosterone output and the corticosterone/pregnenolone ratio to the normal values. The sex differences in steroids secretion by the rat adrenal are partially conditioned by a cholesterol sidechain cleavage activity. Testosterone inhibits this activity, while estradiol under applied experimental conditions has no effect on the cholesterol sidechain cleavage activity.