Sex differences in the extracellular Ca2+-independent release of LH and FSH.
The present study was undertaken to investigate the effects of sex and estrous cycle on the manifestation of the extracellular Ca2+-independent component of gonadotropin secretion. Quartered pituitaries from male, ovariectomized (OVX) females +/- estradiol (E2) implants, and mature females at each stage of the estrous cycle were perifused with Ca2+-free medium. Gonadotropin releasing hormone (GnRH)-stimulated luteinizing hormone (LH) and follicle stimulating hormone (FSH) secretion from male and OVX pituitaries was inhibited in Ca2+-free medium. In contrast, only a partial inhibition was obtained from OVX + E2 or regularly cycling female pituitaries. This extracellular Ca2+-independent component of gonadotropin secretion was lowest at estrus and increased progressively during the estrous cycle. Estradiol replacement in OVX animals resulted in a response similar to that obtained on proestrus. These results indicate that the extracellular Ca2+-independent component of LH and FSH release is only manifest from intact female and not male pituitaries, and is dependent on estradiol.
Bourne
G A
GA
Department of Physiology, University of Alberta, Edmonton, Canada.
Das
S
S
Fahmy
N W
NW
D000818:Animals; D002118:Calcium / Q000378:metabolism / Q000494:pharmacology*; D004958:Estradiol / Q000494:pharmacology; D004971:Estrus / Q000378:metabolism; D005260:Female; D005640:Follicle Stimulating Hormone / Q000378:metabolism*; D007986:Luteinizing Hormone / Q000378:metabolism*; D008297:Male; D010902:Pituitary Gland / Q000187:drug effects / Q000378:metabolism; D010906:Pituitary Hormone-Releasing Hormones / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D012737:Sex Factors
D010906:Pituitary Hormone-Releasing Hormones; D004958:Estradiol; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone; D002118:Calcium