Effect of Estradiol and Progesterone on the LH Release Induced by LH-Releasing Hormone (LH-RH) in Intact Diestrous Rats and Anestrous Ewes

Abstract

The effect of pretreatment with estradiol, progesterone, or a combination of both steroids on the response of serum LH levels to a large dose of LH-RH was investigated. In groups of intact diestrous rats, it was demonstrated that estradiol augmented LH release induced by LH-RH. Progesterone did not block the LH release induced by 1 μg of LH-RH, but suppressed that induced by 0.05 μg LH-RH. In these rats, as well as in intact anestrous ewes, the combination of estradiol and progesterone clearly suppressed the pituitary LH response to LH-RH.