Can leptin and progesterone be involved in fertilization in the horse? cleavage rate after icsi or ivf

Objective of this study was not only to investigate the immunocytochemical detection of leptin (Ob) and leptin receptor (Ob-R) on equine spermatozoa and on horse oocytes (compact and expanded-cumulus; pre and post in vitro maturation) but also to determine whether leptin supplementation (1, 10, 100, 1000 ng/ml) during IVM could have effects on horse oocyte developmental capacity after fertilization or intracytoplasmic sperm injection (ICSI). Results indicated that Ob and Ob-R were located at the post-acrosomal level, in the midpiece and through the tail of equine spermatozoa. The present results showed that leptin demonstrated beneficial effects on meiotic maturation and on fertilization after ICSI but had no effects on embryo development or even negative effects at high concentrations. Leptin and progesterone had effects on capacitation and acrosome reaction but only progesterone allowed sperm penetration by standard IVF. However, the immunocytochemical presence of Ob and Ob-R on equine spermatozoa do not preclude the possible action of leptin on other sperm functions such as sperm-zona pellucida binding and/or zona pellucida-induced acrosome reaction.