Modulation of peroxisome proliferator-activated receptor δ and γ 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 PPAR delta complete coding sequence and mRNA abundance of PPAR delta, PPAR gamma 1 and gamma 2, 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-Land race multiparous (YL) and nulliparous (YLn)), site of endometrial tissue sampling (between and at embryo attachment sites) in crossbred DurocX Yorkshire-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 PPAR delta, 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 PPAR delta, PPAR gamma 1, and ANGPTL4. Finally, day 15 pregnant ML sows had lower PPAR delta mRNA levels compared to day 15 cycling ML sows. A significant increase of PPAR gamma 1 mRNA levels was found on day 25 pregnant NIL and DYL sows relative to day 15 ML or DYL pregnant sows. PPAR delta 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 PPAR delta, PPAR gamma 1, and ANGPTL4, but not PPAR gamma 2, during the peri-implantation period in pregnant sows.