Effect of leptin on oocyte maturation and subsequent pregnancy rate of cloned embryos reconstructed by somatic cell nuclear transfer in pigs

Cloning pigs by somatic cell nuclear transfer (SCNT) has wide applications in basic research, human medicine and agricultural production. To improve cloning efficiency, the effect of two basic maturation media, NCSU-23 and TCM199, was compared, and TCM199 was selected for the following experiments with leptin. We systematically studied the effects of leptin supplementation on oocytes in vitro maturation (IVM), in vitro development of parthenogenetically activated (PA) and SCNT embryos and in vivo development of SCNT embryos after embryo transfer (ET). The results showed that supplementation of 100 or 200 ng/ml leptin into the maturation medium did not greatly affect nuclear maturation of oocytes, or cleavage rates of PA and SCNT (P > 0.05). Blastocyst rates of PA and SCNT embryos were significantly improved when 100 or 200 ng/ml leptin was added to maturation medium, and the number of cells in PA blastocysts was also improved (P < 0.05). The number of cells in blastocyst of SCNT was improved, when 100 ng/ml leptin was added (P < 0.05). Furthermore, supplementation of 100 or 200 ng/ml leptin to the IVM medium may improve pregnancy rate and the delivery rate in pig cloning.