Cigarette Smoking Affects Specific Sperm Oxidative Defenses but Does Not Cause Oxidative DNA Damage in Infertile Men

Objective: To evaluate the effects of tobacco consumption on the oxidative defenses of sperm, the glutathione system (GS), and sperm DNA oxidation.

Design: Double-blind experimental study.

Setting: Andrology laboratory in a university-affiliated private setting.

Patient(s): One hundred seventeen semen samples from infertile males.

Intervention(s): None.

Main Outcome Measure(s): (a) sperm GS enzymatic activity with respect to glutathione peroxidase isoforms GPx-1 and GPx-4, glutathione reductase (GR), and cellular glutathione (GSH) content (n = 29); (b) GPx-1, GPx-4, and GR mRNA expression analysis (n = 33); (c) oxidative DNA damage quantification using OXIDNA assay kit (n = 55). Two groups were established: nonsmoking and smoking males. The t tests were employed to detect significant differences between groups.

Result(s): We identified a significant decrease in sperm GPx-4 activity but not in GPx-1 and GSH activity in smokers compared with nonsmokers. A significant decrease was also observed in GPx-1, GPx-4, and GR mRNA expression in the former group. Interestingly, we did not observe any significant variation in the percentage of cells with oxidative damage of the DNA or in the average level of oxidation of affected cells with respect to the smoking condition of the male.

Conclusion(s): We demonstrate that smoking has a negative impact on intracellular antioxidant enzymes but that effect does not increase oxidative DNA damage. Thus, the effects of reduced oxidative defenses in sperm as a result of cigarette smoking are yet to be elucidated.