Submitted to: Journal of Animal Science Supplement
Publication Type: Abstract Only
Publication Acceptance Date: June 10, 1996
Publication Date: N/A
A strong association between RBP and UF endometrial secretion has been reported throughout pregnancy (J. Anim. Sci. 73:214, 1995). An experiment was conducted to determine steady state concentrations and localization of endometrial RBP and UF mRNA. White crossbred gilts were killed on d 7, 10, 13, or 16 of the estrous cycle (n = 19) or d 7, 10, 13, 16, or 19 of early pregnancy (n= 26). A further 26 gilts were killed on d 25, 30, 40, 50, 60, 70, 80, or 90 of pregnancy. Reproductive tracts were obtained, embryos were removed, and 500 mg endometrium was collected, frozen, and stored at -80 C until RNA was extracted for RBP and UF Northern blot and slot blot analysis. A 1-cm square uterine section was fixed for RBP and UF in situ hybridization. RBP and UF mRNA expression increased (p<.01) markedly from d 7-13 and was similar for both cyclic and pregnant gilts. Following this marked increase during the estrous cycle and early pregnancy, RBP mRNA declined (p<.01) and UF mRNA increased further (p<.01) through d 40 of pregnancy, after which neither changed. Using in situ hybridization, RBP mRNA was nondetectable on d 7 but labeling intensity increased in luminal epithelium by d 13-19 in both cyclic and pregnant gilts. Localization of RBP mRNA changed from luminal to predominately glandular epithelium by d 40 of pregnancy. UF mRNA was nondetectable on d 7, but labeling intensity increased in glandular epithelium by d 13 in cyclic and pregnant gilts and then remained localized in glandular epithelium through d 90 of pregnancy. Results indicated that patterns of RBP and UF mRNA expression are similar to previously determined patterns of endometrial RBP and UF secretion and are independent of the conceptus. Also, the site of production of RBP changes gradually from d 19-40 of pregnancy.