Effects of dopamine and estrogen on the regulation of Pit-1 alpha, Pit-1 beta, and PL-II gene expression in the rat placenta.
Pituitary-specific transcription factor Pit-1 regulates growth hormone and prolactin gene expression in the pituitary. Recently, Pit-1 was shown to be locally synthesized in the rat placenta and is involved in the regulation of rat placental lactogen (PL) gene expression. Pit-1 has three different splicing variants. They are well known as being biologically active. In the present study, we found that Pit-1 beta is also synthesized in the rat placenta and we tried to examine the effects of dopamine and estrogen on the regulation of Pit-1 alpha, beta and PL-II genes expression using the reverse transcription-polymerase chain reaction (RT-PCR) and Northern blot hybridization. A dopamine receptor agonist, bromocriptine, significantly decreased placental Pit-1 alpha, beta, and PL-II mRNA levels. To examine the effect of estrogen on the gene expression of Pit-1 beta, pregnant female rats were ovariectomized (OVX) and injected daily with 17 beta-estradiol. OVX markedly lowered the amount of Pit-1 beta mRNA. Estrogen injection recovered the OVX-induced inhibition of Pit-1 beta mRNA level. Finally, we investigated the site-specific transcription of Pit-1 alpha and beta mRNA in the labyrinth zone and junctional zone of the placental in 15 and 20 days of gestation. The main site of Pit-1 alpha and beta synthesis was shifted from the junctional zone to the labyrinth zone from 15 to 20 days of gestation. Together, these data presume that Pit-1 beta may play a more important role in the placenta than in the pituitary and that Pit-1 may be involved in the regulation of the PL and prolactin-like peptide by estrogen and dopamine in the rat placenta.
Lee
C K
CK
Department of Biology, College of Natural Sciences, Inje University, Kimhae, Korea.
Kang
H S
HS
Lee
B J
BJ
Kang
H M
HM
Choi
W S
WS
Kang
S G
SG
D000818:Animals; D004268:DNA-Binding Proteins / Q000032:analysis / Q000187:drug effects / Q000235:genetics*; D004298:Dopamine / Q000494:pharmacology*; D004967:Estrogens / Q000494:pharmacology*; D005260:Female; D015870:Gene Expression / Q000187:drug effects / Q000235:genetics; D005786:Gene Expression Regulation / Q000187:drug effects; D005865:Gestational Age; D010920:Placenta / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism*; D010928:Placental Lactogen / Q000187:drug effects / Q000235:genetics*; D011247:Pregnancy; D012326:RNA Splicing; D012333:RNA, Messenger / Q000032:analysis / Q000187:drug effects / Q000235:genetics; D051381:Rats; D017207:Rats, Sprague-Dawley; D050817:Transcription Factor Pit-1; D014157:Transcription Factors / Q000032:analysis / Q000187:drug effects / Q000235:genetics*; D014158:Transcription, Genetic / Q000187:drug effects / Q000235:genetics
D004268:DNA-Binding Proteins; D004967:Estrogens; C494186:Pou1f1 protein, rat; D012333:RNA, Messenger; D050817:Transcription Factor Pit-1; D014157:Transcription Factors; C062303:placental lactogen II; D010928:Placental Lactogen; D004298:Dopamine