Modulation of peroxisome proliferator-activated receptor delta and gamma transcripts in swine endometrial tissue during early gestation.

Recent evidence points to a role for peroxisome proliferator-activated receptors (PPARs) delta and gamma in embryo implantation and survival. In this study, we report the porcine PPARdelta complete coding sequence and mRNA abundance of PPARdelta, PPARgamma1 and gamma2, angiopoietin-like protein 4 (ANGPTL4) and adipocyte determination and differentiation-dependent factor 1 (ADD1) genes in the pregnant sow endometrium. Real-time PCR analysis was used to study the effect of parity (Yorkshire-Landrace multiparous (YL) and nulliparous (YLn)), site of endometrial tissue sampling (between and at embryo attachment sites) in crossbred DurocxYorkshire-Landrace (DYL) sows and stages of pregnancy (non-pregnant, day 15 and day 25 after mating) in Meishan-Landrace (ML) on mRNA levels. Parity effects were observed for PPARdelta, ANGPTL4, and ADD1, with higher mRNA levels in YL than YLn sows. In DYL sows, lower mRNA levels were present at attachment sites compared to between attachment sites for PPARdelta, PPARgamma1, and ANGPTL4. Finally, day 15 pregnant ML sows had lower PPARdelta mRNA levels compared to day 15 cycling ML sows. A significant increase of PPARgamma1 mRNA levels was found on day 25 pregnant ML and DYL sows relative to day 15 ML or DYL pregnant sows. PPARdelta and gamma immunostaining was detected in endometrial tissue of day 15 cycling sows, day 15 and 25 pregnant sows and epithelial cells of day 25 embryos. Collectively, our results suggest a role for PPARdelta, PPARgamma1, and ANGPTL4, but not PPARgamma2, during the peri-implantation period in pregnant sows.