Effect of Pre-Incubation of Cryopreserved Sperm with either Kisspeptin or Glutathione to Mitigate Freeze-Thaw Damage

Background: Sperm cryopreservation reduces sperm quality. Kisspeptin (KP) has beneficial effects on sperm functions. This study compares the effect of KP and Glutathione (GSH) on mitigating the detrimental effects of the freeze-thaw cycle on sperm. Methods: An experimental study was conducted in Birjand (Iran) during 2018-2020. Thirty normal swim-up semen samples were treated with Ham's F10 medium (negative control), 1 mM GSH (positive control), or KP (10 mu M) for 30 min before freezing. The motility, acrosome reaction, capacitation, and DNA quality of the frozen-thawed sperms were assessed according to the WHO guidelines. Statistical analysis was performed using paired t test, one-way analysis of variance, and least significant difference. Results: Pre-incubation with KP significantly increased the percentage of sperm motility (34.00 +/- 6.7, P=0.003) compared to the control (20.44 +/- 7.4) and GSH-treated (31.25 +/- 12.2) aliquots. The frequency of non-capacitated spermatozoa was significantly higher in the KP-treated group (98.73%) than in the control (96.46%) and GSH-treated (96.49%) aliquots (P<0.001). The percentage of acrosome-intact spermatozoa in the KP-treated group (77.44%) was significantly higher than the control (74.3%) and GSH-treated (74.54%) groups (P<0.001). The sperm frequency with normal histone in the KP-treated group (51.86%) and with normal protamine (65.39%) was significantly higher than the controls (P=0.001 and P=0.002, respectively). The percentage of TUNEL-positive sperm was significantly lower in the KP-treated group (9.09 +/- 2.71) than both GSH-treated (11.22 +/- 2.73) and control (11.31 +/- 2.2) groups (both P=0.002). Conclusion: Pre-incubation with KP protects sperm motility and DNA integrity from the detrimental effect of the freeze -thaw cycle. KP is suitable as a pre-treatment to control sperm quality during freezing-thawing.