Effects of leptin on in vitro maturation, fertilization and embryonic cleavage after ICSI and early developmental expression of leptin (Ob) and leptin receptor (ObR) proteins in the horse

Abstract

Abstract Background The identification of the adipocyte-derived obesity gene product, leptin (Ob), and subsequently its association with reproduction in rodents and humans led to speculations that leptin may be involved in the regulation of oocyte and preimplantation embryo development. In mice and pigs, in vitro leptin addition significantly increased meiotic resumption and promoted preimplantation embryo development in a dose-dependent manner. This study was conducted to determine whether leptin supplementation during in vitro maturation (IVM) to horse oocytes could have effects on their developmental capacity after fertilization by IntraCytoplasmic Sperm Injection (ICSI). Methods Compact and expanded-cumulus horse oocytes were matured in medium containing different concentrations (1, 10, 100, 1000 ng/ml) of recombinant human leptin and the effects on maturation, fertilization and embryo cleavage were evaluated. Furthermore, early developmental expression of Ob and leptin receptor (Ob-R) was investigated by immunocytochemical staining. Results In expanded-cumulus oocytes, the addition of leptin in IVM medium improved maturation (74% vs 44%, for 100 ng/ml leptin-treated and control groups, respectively; P Conclusion Leptin plays a cumulus cell-mediated role in the regulation of oocyte maturation in the mare. Species-specific differences may exist in oocyte sensitivity to leptin.