Calcitonin expression in rat anterior pituitary gland is regulated by ovarian steroid hormones.
Gonadotroph-derived calcitonin-like peptide (pit-CT) is a potent inhibitor of lactotroph function. We investigated the effect of ovarian hormones on pit-CT mRNA expression in the anterior pituitary (AP) gland of cycling female rats. Levels of mRNAs for pit-CT, CT receptor, prolactin (PRL), and beta-LH during 4-d estrous cycle were determined. In a second study, the effects of estrogens and progesterone on pit-CT and PRL mRNA levels were investigated. In a third group, the effect of estrogen or progesterone depletion on pit-CT mRNA expression was studied. In a fourth group, the effect of passive pit-CT immunization on PRL and LH mRNA expression was examined. Pit-CT mRNA levels varied during estrous cycle. They were highest in diestrus, but lowest in the evening of proestrus. CT-receptor mRNA levels displayed smaller fluctuations. Estrogen repletion caused a decline in pit-CT mRNA expression in ovariectomized rats, but progesterone produced a marked increase. ICI 182,780 prevented the decline of pit-CT mRNA levels during late proestrus-estrus, but RU 486 attenuated pit-CT mRNA levels. Passive CT immunization in diestrus altered PRL and LH mRNA expression, and advanced the estrus cycle. These results suggest that pit-CT mRNA expression is regulated by ovarian hormones, and depletion of pit-CT advances their estrous cycle.
Sun
Ya-Ping
YP
Department of Pharmaceutical Sciences, Texas Tech University Health Sciences Center, Amarillo 79106, USA.
Lee
Tae Jin
TJ
Shah
Girish V
GV
D000818:Animals; D002116:Calcitonin / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D004958:Estradiol / Q000031:analogs & derivatives / Q000494:pharmacology*; D004965:Estrogen Antagonists / Q000494:pharmacology; D004971:Estrus / Q000378:metabolism; D005260:Female; D000077267:Fulvestrant; D006727:Hormone Antagonists / Q000494:pharmacology; D007116:Immunization, Passive; D015735:Mifepristone / Q000494:pharmacology; D010052:Ovariectomy; D010903:Pituitary Gland, Anterior / Q000378:metabolism*; D011374:Progesterone / Q000494:pharmacology*; D011372:Progestins / Q000037:antagonists & inhibitors / Q000276:immunology; D011388:Prolactin / Q000235:genetics; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D011916:Rats, Inbred F344; D018003:Receptors, Calcitonin / Q000235:genetics
D004965:Estrogen Antagonists; D006727:Hormone Antagonists; D011372:Progestins; D012333:RNA, Messenger; D018003:Receptors, Calcitonin; D000077267:Fulvestrant; D015735:Mifepristone; D011374:Progesterone; D004958:Estradiol; D011388:Prolactin; D002116:Calcitonin