Investigation of sperm hsa-mir-145-5p and MLH1 expressions, seminal oxidative stress and sperm DNA fragmentation in varicocele

Background Mechanisms by which varicocele causes infertility are not clear and few studies have reported that some miRNAs show expression alterations in men with varicocele. Recently, sperm promoter methylation of MLH1 has been shown to be higher in men diagnosed with varicocele. This study aimed to assess the potential effects of miR-145, which was determined to target MLH1 mRNA in silico on sperm quality and function in varicocele. Methods Sperm miR-145 and MLH1 expressions of six infertile men with varicocele (Group 1), nine idiopathic infertile men (Group 2), and nine fertile men (control group) were analyzed by quantitative PCR. Sperm DNA fragmentation was evaluated by TUNEL and the levels of seminal oxidative damage and total antioxidant capacity were analyzed by ELISA. Results Our results have shown that sperm expression of miR-145 was decreased in Group 1 compared to Group 2 (P = 0.029). MLH1 expression was significantly higher in Group 2 than the controls (P = 0.048). Total antioxidant level and sperm DNA fragmentations of Group 1 and Group 2 were decreased (P = 0.001 and P = 0.011, respectively). Total antioxidant capacity was positively correlated with sperm concentration (rho = 0.475, P = 0.019), total sperm count (rho = 0.427, P = 0.037), motility (rho = 0.716, P < 0.0001) and normal morphological forms (rho = 0.613, P = 0.001) and negatively correlated with the seminal oxidative damage (rho=-0.829, P = 0.042) in varicocele patients. Conclusion This is the first study investigating the expressions of sperm miR-145 and MLH1 in varicocele patients. Further studies are needed to clarify the potential effect of miR-145 on male fertility.