Background: Asthenozoospermia which is characterized by reduced motility is a condition that affects male fertility. Decreased motility is associated with several factors such as oxidative stress, hormonal imbalance, and genetic disorders. The N-methyl d-aspartate glutamate receptors (NMDAR) are ligand-gated cation channels that cause calcium influx in nerve cells. According to immunocytochemistry data, NMDARs are present in the tail and midpiece of human sperm. Studies revealed that NMDAR agonists increase intracellular calcium and affect sperm motility in newts, and human sperm. Intracellular calcium is one of the crucial factors in the regulation of sperm function, especially sperm motility. Although the actual roles of NMDAR in human sperm function are unknown, their involvement in calcium influx can be associated with some parameters in human sperm that need calcium. Objective: This study was conducted to investigate the expression level of the NMDARs gene in asthenozoospermic men and its correlation with sperm motility for the first time. Materials and Methods: In this experimental study, sperm samples were collected from men referred to the Arak Educational, Cultural and Research Center. The subjects were divided into two groups: normal and asthenozoospermic. The expression level of the NMDAR gene in sperm samples in 30 normal men (control group) and 30 asthenozoospermic men was evaluated using quantitative reverse transcription polymerase chain reaction (RT-PCR). In addition, the progressive motility of sperm in both groups was evaluated according to the World Health Organization (WHO) guidelines and expressed as a percentage. Results: Our results revealed a decrease in the expression level of NMDARs gene in the sperm of asthenozoosperm men compared to the normal group (p<0.05). In addition, Pearson's correlation coefficient showed a positive correlation between the expression of this gene and human sperm motility. Conclusions: Based on our results, sperm motility is associated with NMDAR gene expression in asthenozoospermic men. It can be concluded that NMDARs (as calcium channels) may be associated with reduced sperm motility in these men.
