The in vitro effect of leptin on semen quality of water b uffalo ( Bubalus bubalis ) bulls

The purpose of this study was to evaluate the probable effects of leptin addition indifferentlevels to the semen extender on sperm quality (motility and motility parameters,viability,sperm membrane integrity, and DNA damage). Semen specimens were evaluatedimmediately after leptin addition, equilibration time and after thawing the frozen semen.Fivehealthy buffalo bulls (5 ejaculates from each bull) were used.Each ejaculate was diluted at 37 Cwith tris-based extender containing 0 (control), 10, 20, 50, 100, and 200 ng mL-1leptin. Thediluted semen was kept 4 hr in refrigerator to reach to the equilibration time and thenpacked in 0.5 mL French straws and frozen in liquid nitrogen. Our results showed that, in thefresh semen, no significant difference was observed in all sperm quality parametersevaluated among all of the examined leptin concentrations. Addition of 10 ng mL-1leptin intosemen extender significantly preserved sperm motility, all of the motility parameters, andviability in equilibrated semen compared to that of control group. However,in vitroadditionof 200 ng mL-1leptin, significantly decreased theses parameters. In the frozen thawed semen,all leptin concentrations decreased sperm motility and viability, but significant decrease wasobserved in concentrations of 100 and 200 ng mL-1. Adding leptin to semen extender did nothave any significant influence on sperm DNA damage andsperm membrane integrity in allexamined groups. These findings suggest thatin vitroaddition of 10 ng mL-1leptin couldpreserve sperm motility and viability in cooled semen of buffaloes.