Leptin acts via transmembrane receptors, which show structural similarity to the class I cytokine receptor family. The leptin receptor is produced in several Abiraterone Sigma alterna tively spliced forms that have in common an extracellular domain of over 800 amino acids, a transmembrane domain of 34 amino acids and a variable intracellular domain, characteristic for each of the isoforms. These iso forms can be classified into three main classes short, long and secreted. In the mouse, Ryan et al. using immunohistochemis try, observed protein expression of the long form of the leptin receptor in the ovary, with high intensities observed in oocytes, thecal cells and corpora lutea with peak expression at ovulation. In the pig, Craig et al.

Inhibitors,Modulators,Libraries demonstrated that Ob R is expressed in oocytes from all stages of follicular development and oocyte maturation, with the highest level of expression occurring in oocytes from medium follicles and at GVBD, Inhibitors,Modulators,Libraries indicating that its expression is dependent on follicular stage and oocyte maturation. In the horse, in vitro fertilization has been for a long time unsuccessful and reasons have been related to incomplete in vitro oocyte maturation. ineffi cient sperm capacitation or changes in oocyte Inhibitors,Modulators,Libraries zona pellucida. In a recent study, McPartlin et al. characterized stallion sperm hyperactivation and demon strated that hyperactivation of capacitated sperm sup ported equine IVF. Intracytoplasmic sperm injection has been adopted as an alternative method to con ventional IVF because sperm injection eliminates prob lems related to sperm binding and penetration but the complexity of oocyte maturation has not yet been over came.

ICSI is a valid tool for evaluating cleavage rates of in vitro matured horse oocytes and ooplasmic maturation. Several studies reported a cleavage rate of 50 80%. Unfortunately, only a small percentage of cleaved zygotes Inhibitors,Modulators,Libraries goes on to form blastocysts in culture. This result may reflect the poor cytoplasmic maturation of equine oocytes matured in vitro. In Inhibitors,Modulators,Libraries the literature, dif ferent culture media have been evaluated to improve the rate of equine oocyte maturation, including http://www.selleckchem.com/products/PF-2341066.html TCM199, B2 and Hams F10, supplemented with dif ferent concentrations of serum, hormones or follicular fluid. These conditions resulted in maturation rates vary ing from 20 to 85% but none of these has increased the efficiency of IVF or ICSI. The presence of leptin and leptin receptor in equine oocytes have been previously evidenced by an immunocy tochemical study in compact cumulus oocytes recovered immediately upon collection and after in vitro maturation from fillies and from mares of light or heavy body weight breeds. To our knowledge, studies on the effects of leptin in equine oocytes and embryos were not reported to date.