title: Progesterone inhibits the estrogen-induced prolactin gene expression in the rat pituitary.
abstract: The present study examines the inhibitory action of progesterone (P) on prolactin (PRL) gene expression in the anterior pituitary of ovariectomized, estradiol (OVX+E) treated adult rats. A single injection of P (1 mg) was administered s.c. to OVX+E treated rats, and animals were killed at 3, 6, 9, and 36 h following P administration. Northern blot analysis showed that P suppressed the E-enhanced PRL mRNA level at 3, 6, and 9 h, but not at 36 h following P administration. When the second injection of P (1 mg) was given at 30 h after the first P, it again suppressed the E-induced PRL mRNA level, indicating that the inhibitory effect of P may not last until 36 h. The inhibitory action of P was dose-dependent, and the pretreatment of RU486 (100 micrograms/rat), a P receptor antagonist at 1 h before P injection partially restored PRL mRNA level which was inhibited by P. These data indicate that P plays a crucial role in the regulation of PRL gene expression in the rat pituitary.
authors.affiliation: Department of Molecular Biology, College of Natural Sciences, Seoul National University, South Korea.
authors.forename: B N
authors.initials: BN
authors.lastname: Cho
authors.forename: Y H
authors.initials: YH
authors.lastname: Suh
authors.forename: Y D
authors.initials: YD
authors.lastname: Yoon
authors.forename: C C
authors.initials: CC
authors.lastname: Lee
authors.forename: K
authors.initials: K
authors.lastname: Kim
mesh_terms: D000818:Animals; D004958:Estradiol / Q000494:pharmacology*; D005260:Female; D005786:Gene Expression Regulation / Q000187:drug effects*; D015735:Mifepristone / Q000494:pharmacology; D010052:Ovariectomy; D010903:Pituitary Gland, Anterior / Q000187:drug effects* / Q000378:metabolism; D011374:Progesterone / Q000494:pharmacology*; D011388:Prolactin / Q000096:biosynthesis* / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics; D051381:Rats; D017207:Rats, Sprague-Dawley; D011980:Receptors, Progesterone / Q000037:antagonists & inhibitors
chemical_list: D012333:RNA, Messenger; D011980:Receptors, Progesterone; D015735:Mifepristone; D011374:Progesterone; D004958:Estradiol; D011388:Prolactin