Characteristics of an antigonadotrophic GnRH-like protein in the ovaries of diverse mammals.
A GnRH-like protein, detected with a receptor assay for GnRH in rat ovarian membranes, is present in ovarian extracts of the rat, human, cow and ewe at levels much higher than immunoreactive GnRH. This protein has been partly purified and characterized from bovine ovaries. Highest levels of this protein are found in granulosa cells, but substantial activity is present in luteal, thecal and stromal tissue. No detectable GnRH-like activity is found in follicular fluid, or in ovarian venous or jugular plasma. The GnRH-like protein is structurally and immunologically different from GnRH, but it competitively and reversibly inhibits binding of GnRH to high-affinity sites in rat ovarian membranes. The GnRH-like protein markedly inhibits the action of both LH and FSH in cultures of rat luteal and granulosa cells, respectively, to a much greater extent than GnRH. Co-elution of receptor-binding activity and antigonadotrophic activity occurs within and between several chromatography procedures, but the protein has not been completely purified. The presence of this antigonadotrophic GnRH-like protein in the ovaries of diverse species raises the possibility that it may represent a novel paracrine regulator of ovarian function.
Behrman
H R
HR
Department of Obstetrics/Gynecology, Yale University School of Medicine, New Haven, CT 06510.
Aten
R F
RF
Ireland
J J
JJ
Milvae
R A
RA
D000328:Adult; D000818:Animals; D002417:Cattle; D000242:Cyclic AMP / Q000378:metabolism; D005260:Female; D006801:Humans; D008322:Mammals / Q000378:metabolism*; D010053:Ovary / Q000032:analysis*; D010906:Pituitary Hormone-Releasing Hormones / Q000378:metabolism* / Q000502:physiology; D011247:Pregnancy; D051381:Rats; D011966:Receptors, LHRH / Q000378:metabolism; D012756:Sheep
D010906:Pituitary Hormone-Releasing Hormones; D011966:Receptors, LHRH; D000242:Cyclic AMP