Effect of steroids on ACTH release from cultured pituitary cells of the rat

Using a primary cell culture of rat anterior pituitary and corticotropin (ACTH) RIA, the effects of various steroids have been investigated. Dexamethasone inhibited the ACTH release stimulated by alpha-melanotropin and Pitressin (posterior pituitary extract), but did not influence the non-stimulated release. The effect of all the investigated steroids was significant; aldosterone exhibited a more marked inhibition than spironolactone. Simultaneous administration of aldosterone and spironolactone resulted predominantly in the manifestation of spironolactone action. A new effect of spironolactone has been demonstrated in vitro; the evaluation of its pharmacological importance requires studies in vivo.