Protective effect of leptin on human sperm after cryopreservation

Abstract

Objective To investigate the effect of leptin on the quality and function of sperm after freezing and thawing by adding leptin to human sperm cryoprotective solution. Methods Semen samples were collected at the Reproductive Medicine Center of the Third Affiliated Hospital of Inner Mongolia Medical University from January to December 2017. Samples with a progressive sperm ratio≥32% and sperm concentration ≥15×106/ml were included in a normal group, while those with a progressive sperm ratio<32% and sperm concentration <15×106/ml were included in an asthenozoospermia (AS) group. The liquefied semen samples were mixed with cryopreserved solution with and without leptin. Vitality rate, motility rate, and DNA fragmentation index (DFI) were measured. Malondialdehyde content and reactive oxygen level in sperm were detected. Comparisons among groups were analyzed by single factor analysis of variance, and comparisons between groups were performed by the LSD-t test. Results When leptin was added at a concentration of 10 ng/ml, the total vitality of sperm after cryo-resuscitation was the highest, reaching (53.7±1.5)%. Compared with fresh sperm, the total vitality rate [(41.5±6.9)% vs (69.9±6.3)%, t=15.7, P 0.05). After freezing and thawing, compared with the control group, the sperm in the AS group had significantly increased total viability [(24.8±2.0)% vs (17.9±2.9)%, t=10.5, P<0.001] and motility rate[(49.5±3.8)% vs (39.5±4.4)%, t=9.4, P<0.001], and significantly decreased DFI [(49.5±3.8)% vs (39.5±4.4)%, t=10.2, P<0.001], active oxygen (fluorescence intensity, 37.9±4.2 vs 64.9±2.9, t=28.5, P<0.001), and malondialdehyde (nmol/108 sperm, 23.1±1.7 vs 33.6±2.0, t=21.9, P<0.001). Conclusion The addition of leptin can effectively reduce sperm motility and viability, DNA fragmentation, and oxidative damage caused by cryopreservation, thereby improving sperm quality and function. Key words: Leptin; Freezing-thawing; DNA fragmentation; Oxidative stress damage; Sperm function