The acute stimulatory effect of estrogen on gonadotropin release in gonadotropin-releasing hormone-primed women.
In order to prove the acute stimulatory effects of estrogen on pituitary gonadotropin release, we have performed the present experiments in 8 women with a hypergonadotropic state due to surgical castration or primary ovarian failure. They received gonadotropin releasing hormone (Gn-RH) for 12-21 h at the constant rate of 20 micrograms/h. In 5 of the women, estradiol-17 beta was concomitantly administered at the rate of 20 micrograms/h from 6 h after the start of Gn-RH infusion. Blood samples were collected frequently throughout the experiments for the analysis of LH, FSH and estradiol. In response to the sole stimulation of Gn-RH, remarkable and prompt rises in LH (313.5%), but to a lesser degree in FSH (194.2%), were observed within the initial 3 h, and their high levels were maintained throughout the experimental period. However, the additional administration of estradiol brought on a further sudden rise in both gonadotropins levels: 178.3% for LH and 163.5% for FSH within 2 h. These high levels were sustained during estradiol infusions. In 2 of them, blood samples were obtained for several hours after cessation of estradiol infusion. The circulating gonadotropin level dropped precipitously close to the baseline level within 3 h after estradiol infusions. Our data indicate that estrogen has an acute and strong augmentative effect on Gn-RH induced gonadotropin release in addition to its conventional negative and positive feedback effects.
D000328:Adult; D004958:Estradiol / Q000502:physiology*; D005260:Female; D005640:Follicle Stimulating Hormone / Q000097:blood; D006062:Gonadotropins / Q000097:blood / Q000378:metabolism*; D006801:Humans; D007006:Hypogonadism / Q000097:blood; D007262:Infusions, Intravenous; D007986:Luteinizing Hormone / Q000097:blood; D010052:Ovariectomy; D010906:Pituitary Hormone-Releasing Hormones / Q000008:administration & dosage* / Q000494:pharmacology
D006062:Gonadotropins; D010906:Pituitary Hormone-Releasing Hormones; D004958:Estradiol; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone