Varicocele negatively affects sperm mitochondrial respiration

OBJECTIVE: To evaluate the effect of varicocele on oxidative stress, sperm mitochondrial respiratory efficiency, sperm morphology and semen parameters. METHODS: 20 patients with varicocele and 20 normozoospermic subjects without varicocele (control group) were recruited from a medical center for reproductive biology. The levels of serum reactive oxygen metabolites and seminal lipid peroxides were assessed for both control and varicocele subjects. Sperm DNA fragmentation was measured by sperm chromatin dispersion test. Mitochondrial respiratory activity was evaluated with a polarographic assay of oxygen consumption carried out in hypotonically-treated sperm cells. RESULTS: In this study, varicocele patients were compared with men without varicoceles. Oxidative stress was observed in the serum and seminal fluid of varicocele patients. These patients showed an increase of 59% (P < 0.05) in serum reactive oxygen metabolites and a threefold increase in the level of sperm lipid peroxides. A parallel and significant increase (a twofold increase; P < 0.05) in the degree of sperm DNA fragmentation was also observed. Varicocele patients showed a 27% decrease (P < 0.05) in mitochondrial respiratory activity in comparison to the control group. A 32% increase (P < 0.05) in sperm midpiece defects and a 41% decrease (P < 0.05) in sperm concentration and motility were also observed. CONCLUSIONS: Men with varicocele have increased markers of oxidative stress and decreased mitochondrial respiratory activity. These results correlated with abnormalities in semen parameters. For morphology these correlated with midpiece defects.