Expression of estrogen receptor subtypes in rat pituitary gland during pregnancy and lactation.
The aim of this study was to examine whether the expression levels of mRNA of the three estrogen receptor (ER) subtypes, ERalpha, ERbeta, and truncated ER product-1 (TERP-1) found in the rat pituitary gland were modified during gestation, lactation, and postlactation periods. By using relative quantitative RT-PCR, we found that ERalpha mRNA significantly peaked in midpregnancy. However, the ERalpha protein level remained constant. ERbeta gene expression did not change throughout pregnancy, suggesting that it was not related to estradiol levels during this reproductive period. In contrast, both TERP-1 mRNA and protein levels dramatically increased throughout the second half of gestation, being faintly detectable in early pregnancy. TERP-1 expression was rapidly reversed by lactation, whereas neither pituitary ERalpha nor ERbeta relative levels were significantly altered. In addition, pup removal for 24-96 h on d 9 postpartum significantly reduced the expression of both ERalpha and ERbeta mRNA compared with that in lactating animals, but the expression of TERP-1 mRNA was no longer detected. Collectively, our data indicate that 1) TERP-1, ERalpha, and ERbeta expression levels are differentially regulated in the pituitary; 2) TERP-1 is variably expressed depending on the hormonal environment related to the estrous cycle, pregnancy, and lactation; and 3) TERP-1/ERalpha ratios dramatically change depending on reproductive periods, suggesting a critical role for TERP-1 in reproductive events.
Vaillant
Colette
C
Université de Rennes I, Interactions Cellulaires et Moléculaires, Equipe Information et Programmation Cellulaires, Centre National de la Recherche Scientifique, UMR 6026, Campus de Beaulieu, 35042 Rennes, France.
Chesnel
Franck
F
Schausi
Diane
D
Tiffoche
Christophe
C
Thieulant
Marie-Lise
ML
D000818:Animals; D015153:Blotting, Western; D004958:Estradiol / Q000097:blood; D047628:Estrogen Receptor alpha; D047629:Estrogen Receptor beta; D030762:Estrous Cycle; D005260:Female; D015870:Gene Expression; D005865:Gestational Age; D007774:Lactation / Q000502:physiology*; D010902:Pituitary Gland / Q000378:metabolism; D011247:Pregnancy; D011270:Pregnancy, Animal / Q000502:physiology*; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D017207:Rats, Sprague-Dawley; D011960:Receptors, Estrogen / Q000032:analysis / Q000235:genetics*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014886:Weaning
D047628:Estrogen Receptor alpha; D047629:Estrogen Receptor beta; D012333:RNA, Messenger; D011960:Receptors, Estrogen; C118565:TERP-1; D004958:Estradiol