Effects of adrenocortical and gonadal steroids on the secretion in vitro of corticotrophin and its hypothalamic releasing factor

Abstract

The effects of adrenocortical and gonadal steroids on the secretion in vitro of ACTH by adenohypophysial segments and corticotrophin releasing factor (CRF) by isolated hypothalami were studied in the rat. Corticosterone (1·25 × 10−6 mol/l), betamethasone (2·5 × 10−8 mol/l) and progesterone (2·5 × 10−7 mol/l) reduced the hypothalamic extract-induced secretion of ACTH by pituitary tissue in vitro but aldosterone (2 × 10−7 mol/l), testosterone, androsterone, androstenedione (2 × 10−7 mol/l), oestradiol, oestriol and oestrone (10−6 mol/l) did not. Corticosterone (2·5±10−9 mol/l), aldosterone (2×10−8 mol/l) and betamethasone (2 × 10−10 mol/l) inhibited and oestradiol, oestriol and oestrone (10−8–10−6 mol/l) potentiated the production of CRF by isolated hypothalami which occurred when acetylcholine or 5-hydroxytryptamine were added to the incubation medium but progesterone (2·5 × 10−7 mol/l), testosterone, androsterone and androstenedione (2 × 10−7 mol/l) had no effects. The results indicate that hypothalamo-pituitary-adrenocorticotrophic activity may be modified not only by glucocorticoids but also by other steroids.