Free alpha-subunit response to gonadotropin-releasing hormone in women with polycystic ovaries.
The response of glycoprotein hormone free alpha-subunit to gonadotropin-releasing hormone (GnRH) was evaluated in 12 women with polycystic ovaries (PCOs). Six of these women were premedicated for 3 days with micronized 17 beta-estradiol before receiving a 100-micrograms bolus of GnRH. In nonmedicated PCO patients, GnRH did not significantly alter basal free alpha-subunit levels. In four of the six PCO patients receiving estrogen premedication, a significant increase in free alpha-subunit was observed; these four patients had low progesterone levels at the time of the GnRH test. Among the six premedicated patients, two had elevated (greater than 4 ng/ml) progesterone levels, and the GnRH tests showed no significant effect on the levels of free alpha-subunit. The study revealed a dissociation between the free alpha-subunit responses to GnRH and the responses of luteinizing hormone; a closer relationship was observed between free alpha-subunit and follicle-stimulating hormone responses. It was concluded that the lack of a free alpha-subunit response to GnRH in PCO patients is not due to a primary inability of the pituitary gonadotroph to produce free alpha-subunit but is a consequence of an altered estrogenic milieu, and a free alpha-subunit response to GnRH may reflect the replenishment of both follicle-stimulating hormone and luteinizing hormone in the gonadotrope.
D000328:Adult; D004359:Drug Therapy, Combination; D004958:Estradiol / Q000627:therapeutic use; D005260:Female; D015292:Glycoprotein Hormones, alpha Subunit; D006628:Hirsutism / Q000097:blood / Q000188:drug therapy; D006801:Humans; D007247:Infertility, Female / Q000097:blood / Q000188:drug therapy; D008875:Middle Aged; D010446:Peptide Fragments / Q000097:blood*; D010906:Pituitary Hormone-Releasing Hormones / Q000627:therapeutic use*; D010908:Pituitary Hormones, Anterior / Q000097:blood*; D011085:Polycystic Ovary Syndrome / Q000097:blood* / Q000188:drug therapy; D011863:Radioimmunoassay; D013997:Time Factors
D015292:Glycoprotein Hormones, alpha Subunit; D010446:Peptide Fragments; D010906:Pituitary Hormone-Releasing Hormones; D010908:Pituitary Hormones, Anterior; D004958:Estradiol