Effects of L-carnitine in different concentrations on DNA fragmentation, mitochondrial membrane potential and acrosome reaction during human sperm cryopreservation

Abstract

Objective To investigate the effects of L-carnitine in different concentrations on DNA fragmentation index (DFI), mitochondrial membrane potential (MMP) and acrosome reaction (AR) during human sperm cryopreservation. Methods Forty patients were randomly selected from the June 2017 to November 2017 in the Second Affiliated Hospital of Zhengzhou University. Experiments were carried out on the patient consent. In addition, the semen samples were collected by masturbation method.All semen samples were fully mixed and divided into five groups: group A with fresh semen as control, group B0 with conventional cryoprotectant, group B5 with 5 mmol/L L-carnitine, group B10 with 10 mmol/L L-carnitine, group B20 with 20 mmol/L L-carnitine. The semen samples were frozen by liquid nitrogen vapor, and then were thawed 48h later. Computer-aided sperm analysis was used to detect the progressive motility (PR) and viability of spermatozoa before and after cryopreservation. Flow cytometry was used to detect DFI, MMP and AR in each group. Results The PR, motility and MMP after freezing were significantly lower than those before freezing. The sperm DFI was higher than that before freezing.There was no difference in the likelihoods of the PR on motility between four frozen groups (P>0.05). The sperm DFI of spermatozoa were as follows: B10 0.05). Conclusions Sperm cryopreservation would lead to frozen injury, which can reduce PR, sperm motility, MMP Besides, sperm cryopreservation also lead to sperm DFI increasing; cryoprotectant added with 10 mmol/L L-carnitine or 20 mmol/L L-carnitine group can reduce the sperm DFI and alleviate decrease in MMP. In this way, the effects of sperm cryopreservation can be improved. Moreover, 10 mmol/L of L-carnitine can be used as an active ingredient to protect spermatozoa in human sperm cryopreservation. Key words: L-carnitine; Sperm cryopreservation; DNA fragmentation; Mitochondrial membrane potential; Acrosome reaction