ESTIMATION OF PREGNENOLONE SYNTHESIS IN RAT ADRENAL HOMOGENATES - SOME COFACTOR REQUIREMENTS - EFFECTS OF STRESS, HYPOPHYSECTOMY, CORTISONE AND ACTH

  • 1 January 1977
    • journal article
    • research article
    • Vol. 69  (1) , 74-86
Abstract
Pregnenolone synthesis was estimated in whole adrenal homogenates incubated in the presence of cyanoketone (2.alpha.-cyano-4,4,17.alpha.-trimethyl-androst-5-en-17.beta.-ol-3-one). The yield of pregnenolone depended on the type of incubation medium employed. Both Ca2+ and bovine serum albumin (BSA) stimulated the rate of pregnenolone synthesis as did an NADPH or NADPH generating system. Aminoglutethimide added in vitro inhibited cholesterol side chain cleavage activity. Ether stress in vivo stimulated pregnenolone synthesis in vitro, and hypophysectomy of 24 h duration resulted in a decrease. Cortisone administration for 8 days reduced formation of pregnenolone by rat adrenal homogenates, an effect prevented by concomitant treatment with ACTH. Hypophysectomy of 8 days duration decreased pregnenolone synthesis, and ACTH replacement reversed this effect. Changes in pregnenolone synthesis were paralleled by changes in corticosterone and total steroid production.