Involvement of progesterone in gonadotrophin-induced pituitary adenylate cyclase-activating polypeptide gene expression in pre-ovulatory follicles of rat ovary.
The present study was designed to determine whether progesterone might have a role in gonadotrophin-induced pituitary adenylate cyclase-activating polypeptide (Pacap) gene expression in rat ovary. Northern blot analysis revealed that treatment of pregnant mare's serum gonadotrophin (PMSG)-primed immature rats with the progestin antagonist RU486 or an inhibitor of 3beta-hydroxysteroid dehydrogenase epostane, 1 h before HCG, resulted in a dose-dependent inhibition of the HCG-induced Pacap gene expression. In-situ hybridization demonstrated that the number of pre-ovulatory follicles expressing Pacap mRNA in their granulosa cells was greatly reduced in ovaries treated with RU486. Moreover, the suppressive effect of RU486 or epostane on the LH-induced Pacap gene expression in cultured pre-ovulatory follicles was reversed by co-treatment with the synthetic progestin R5020. We further cloned the 5'-flanking region of the rat Pacap gene and identified the presence of a consensus progesterone receptor element. When luciferase fusion genes containing Pacap gene promoter were transiently transfected into granulosa cells of pre-ovulatory follicles, luciferase activity was markedly stimulated by LH. Treatment with RU486 or epostane resulted in partial suppression of LH-stimulated PACAP promoter activity. Taken together, these results indicate that progesterone, acting through progesterone receptors, plays a role in gonadotrophin induction of Pacap gene expression in granulosa cells of pre-ovulatory follicles, and thereby may be involved in the process of ovulation.
Park
J I
JI
Hormone Research Center, Chonnam National University, Kwangju 500-757, Republic of Korea.
Kim
W J
WJ
Wang
L
L
Park
H J
HJ
Lee
J
J
Park
J H
JH
Kwon
H B
HB
Tsafriri
A
A
Chun
S Y
SY
D000737:Androstenols / Q000494:pharmacology; D000818:Animals; D001483:Base Sequence; D002478:Cells, Cultured; D016384:Consensus Sequence; D046508:Culture Techniques; D005260:Female; D005786:Gene Expression Regulation / Q000187:drug effects*; D006062:Gonadotropins / Q000494:pharmacology*; D006107:Granulosa Cells / Q000166:cytology; D051379:Mice; D015735:Mifepristone / Q000494:pharmacology; D008969:Molecular Sequence Data; D009479:Neuropeptides / Q000235:genetics*; D006080:Ovarian Follicle / Q000187:drug effects*; D010060:Ovulation / Q000502:physiology; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide; D011374:Progesterone / Q000502:physiology*; D011372:Progestins / Q000494:pharmacology; D011401:Promoter Regions, Genetic; D051381:Rats; D017207:Rats, Sprague-Dawley; D020218:Response Elements; D012689:Sequence Homology, Nucleic Acid; D014162:Transfection
C495402:Adcyap1 protein, mouse; C495403:Adcyap1 protein, rat; D000737:Androstenols; D006062:Gonadotropins; D009479:Neuropeptides; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide; D011372:Progestins; D015735:Mifepristone; D011374:Progesterone; C046855:epostane