EFFECT OF CORTICOTROPHIN AND CORTICOSTEROIDS ON PLASMA INTERSTITIAL CELL-STIMULATING HORMONE AND URINARY STEROIDS IN THE BOAR

Abstract

SUMMARY Levels of interstitial cell-stimulating hormone (ICSH) activity in plasma estimated by the rat ovarian cholesterol depletion method and urinary gonadal steroid excretion were studied in boars under various experimental conditions. Injections of adrenocorticotrophic hormone (ACTH), hydrocortisone and prednisolone trimethylacetate were found to lower the level of plasma ICSH and urinary dehydroepiandrosterone (DHA) and oestrogens. This action of ACTH is thought to be mediated through the adrenal cortex since ACTH did not reduce urinary DHA or plasma ICSH activity in the adrenalectomized boar. Hydrocortisone reduced ICSH activity in the castrated boar. When hydrocortisone was administered at the same time as testicular steroidogenesis was stimulated by chorionic gonadotrophin in young hypophysectomized or intact boars, no pronounced influence was found on their elevated DHA excretion. It is concluded that in the boar some adrenal corticosteroids are capable of depressing plasma ICSH activity which results in reduced testicular steroidogenesis.