Expression of TRPV1 as A Heat Sensitive Voltage-Dependent Ion Channel and Oxidative Stress in Sperm Samples of Infertile Men with Varicocele: A Case-Control Study

Objectives: Transient receptor potential vanilloid 1 (TRPV1) is a heat-activated nonselective cation channel that plays important role in the spermatogenesis, capacitation, acrosome reaction and sperm/oocyte fusion. Considering the high testicular temperature and oxidative stress in varicocele condition, we aimed to assess expression of TRPV1 in sperm of infertile men. Materials and Methods: In this case-control study, twenty-five men with varicocele (grade II and III) as well as twentyfive fertile were recruited. Sperm parameters, protamine deficiency (Chromomycin A3), DNA damage (TUNEL), lipid peroxidation (BODIPY), TRPV1 gene expression (real time polymerase chain reaction), TRPV1 protein (flowcytometry and immunocytochemical techniques), and acrosome reaction were assessed between fertile and varicocele groups. Results: We observed a significant decrease in the sperm parameters, and also, an increased DNA damage, lipid peroxidation, and protamine deficiency in varicocele group. Although, the mRNA expression of TRPV1 was similar between varicocele and fertile groups, its expression at the protein level was significantly decreased in the varicocele group in comparison with fertile group. Additionally, the TRPV1 localization was changed from the equatorial region to the acrosomal region of the head, especially in the acrosomal region, which was more significant in the fertile group than the varicocele group after inducing acrosome reaction. Conclusion: In addition to the quality of sperm parameters, and chromatin integrity that were lower significantly in varicocele group, the expression of TRPV1 protein was also lower in varicocele condition that could be associated with reduced capacitation, acrosome reaction and sperm/oocyte fusion and thereby infertility.