Low NRF2 mRNA Expression in Spermatozoa from Men with Low Sperm Motility

Antioxidant genes and enzymes play important roles in human spermatogenesis. Although low levels of antioxidant enzyme expression are associated with poor sperm quality, it is not clear whether mRNA expression of antioxidant genes is lower in these men than in normozoospermic men. In this study, 55 asthenozoospermic and oligoasthenozoospermic patients and 65 controls were recruited. Quantitative real-time reverse transcription PCR was performed and the abundance of mRNA of four antioxidant genes known to be important to spermatogenesis were evaluated. These genes were nuclear factor erythroid 2-related factor 2 (NRF2), catalase (CAT), glutathione S-transferase Mu 1 (GSTM1), and superoxide dismutase isoenzyme 2 (SOD2). Results showed the level of NRF2 mRNA expression to be significantly lower in patients than in controls (P < 0.001), but no statistically significant difference in the level of SOD2, CAT, or GSTM1 gene expression was observed between the two groups. A significant correlation was observed between the level of NRF2 mRNA expression and specific sperm function parameters, including concentration, progressive motility, immotility, vitality, and morphology (all P < 0.01). NRF2 expression was also found to be associated with seminal SOD activity and mRNA levels of the CAT and SOD2 genes (all P < 0.05). Therefore, our data demonstrated that the level of NRF2 mRNA expression is significantly lower in human males with low sperm motility and correlated with specific sperm function parameters. This suggests that NRF2 is important to spermatogenesis and may serve as a useful biomarker in the prediction of male infertility.