EFFECTS OF STEROID HORMONES ON GONADOTROPHIN SECRETION IN FEMALE RATS AFTER OVARIECTOMY DURING THE OESTROUS CYCLE

Abstract

SUMMARY After ovariectomy at dioestrus, a dose of 2·5 μg oestradiol or oestradiol benzoate restored uterine weights and the vaginal smear pattern to normal but did not reproduce the normal ovulatory surge of luteinizing hormone secretion at pro-oestrus. Progesterone in addition to oestrogen was more effective than oestrogen alone in stimulating luteinizing hormone secretion but responses at pro-oestrus or at oestrus were not normal. Deviations from the normal pattern of changes in plasma oestradiol concentration do not provide an adequate explanation for the failure of steroid replacement in these circumstances. Inhibition of the priming effect of exogenous oestrogen by adrenal progesterone released by the stress of operation may provide an explanation.