Steroid Induction of Gonadotropin Surges in the Immature Rat. II. Triggering Ability of Progesterone Metabolites,Adrenocortical Hormones, and Adrenocorticotropin*

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Abstract
Several adrenocortical steroids were tested for their ability to trigger LH [lutropin] release in estrogen-primed sexually immature female rats. Massive LH surges, approaching these known to be triggered by progesterone (P), followed the injection of depot ACTH1-24 and also of the adrenal steroids deoxycorticosterone (DOC) and 4-pregnen-21-ol-3,20-dione 21-acetate, but not of 5.alpha.- and 5.beta.-pregnan-21-ol-3,20-dione, corticosterone, or aldosterone. Estrogen-primed adrenalectomized/ovariectomized rats also responded to DOC, albeit to a lesser extent. The P metabolities 5.alpha.-pregnane-3,20-dione, 4-pregnen-20.alpha.-ol-3-one and 3.alpha.-hydroxy-5.alpha.-pregnan-20-one proved ineffective, although their triggering ability in adults were confirmed. Adrenal P and DOC are potent activators of the gonadotropin surge system underlying pubertal ovulation and P metabolites may acquire biological properties during sexual maturation.