Varicocele Time-dependently Affects DNA Integrity of Sperm Cells: Evidence for Lower In vitro Fertilization Rate in Varicocele-positive Rats

BACKGROUND We designed this study to clarify how varicocele can time-dependently affect sperm morphological parameters and DNA integrity. In this study, we intend to estimate the effect of various periods of varicocele on the in vitro fertilization (IVF) rate in rats. MATERIALS AND METHODS In this experimental study, left varicocele were induced as the test group (n=18) which was further sub-divided into three groups based on the study termination time (4, 6 and 8 months after varicocele induction). The control-sham group (n=6) consisted of rats who received no treatment. Repopulation index (RI), tubular differentiation index (TDI), sperm viability and motility, morphological maturity, chromatin integrity and ability to undergo IVF were assessed. In addition, the potential impact of varicocele on serum total antioxidant capacity (TAOC) and total thiol molecules (TTM) were examined. RESULTS Histological results showed that varicocele negatively influenced TDI and RI. All sperm morphological parameters were lower than those in the control-sham group. DNA damage was severely and time-dependently substantiated in all test groups. Varicocele significantly reduced the ability of sperm derived from varicocele rats to undergo IVF. Serum TAOC and TTM levels reduced in a time-dependent manner. Right testes varicocele-induced rats showed remarkably less damaged profile for all investigated parameters compared to the left testes varicocele. CONCLUSION Our data suggested that experimentally induced varicocele negatively impacted sperm maturation and chromatin integrity in a time-dependent manner. This consequently caused a remarkable reduction in IVF ability. The detrimental effect of varicocele may be attributed to the significant reduction of antioxidant capacity of the serum.