Inhibition by Adrenocorticotrophin of Gonadotrophin-Induced Ovulation in Immature Female Rats

ACTH blocks PMS-induced ovulation in infantile rats. This effect is exerted at the hypothalamic level rather than directly on the ovary; it is not exerted directly by ACTH, but by a secretory product of the adrenal. A large difference between corticosterone and dexamethasone was demonstrated. Corticosterone did not block PMS-induced ovulation by systemic injection. On the other hand, dexamethasone was active when given systemically or when injected into the medial preoptic area. It seemed to be less effective when injected into the ventromedial-arcuate complex. It may be inferred that the medial preoptic area leads neural regulation of gonadotrophin release under influence of both ovarian and adrenal hormones. (Endocrinology 84: 308, 1969)