Leptin enhances porcine preimplantation embryo development in vitro

Recent studies have suggested that leptin plays an important role in reproduction. Ob-R is expressed in the murine embryo, and is suggested to play a role in embryo development, although contradictory results have been reported. In the present study, Ob-R expression was observed both at the mRNA and protein levels in porcine early embryos. We have also demonstrated that leptin is produced in the porcine oviduct, making it spatially available to interact with its receptor during preimplantation development. When included at 10 ng/ml in embryo culture medium, leptin significantly increased the proportion of cleaved embryos (P < 0.01). At day 7 of in vitro culture, leptin at 10 and 100 ng/ml increased the proportion of embryos reaching the blastocyst stage (P < 0.01). We have previously observed that leptin increases oocyte maturation in vitro, and here we report that inclusion of leptin in both IVM and embryo culture medium further increased blastocyst development (P < 0.05), compared to when leptin was included in the embryo culture alone, suggesting leptin has a synergistic role on both oocyte maturation and preimplantation embryo development.