Deleterious impact of short duration UV-A exposure on the human sperm cell –An in vitro study

Background: Environmental stressors like radiation are a cause for male infertility. The quantum of UV-A in solar ultraviolet (UV) radiation surpasses the amount of UVB by 10 to 100 times, penetrates deeper than UV-B into tissue and mediates possible molecular damage, which warrants evaluation of the impact of UV-A on human spermatozoa. Aim: To determine the differences in effects and responses of UV-A exposure on sperm cells from fertile volunteers and infertile men. Materials and Methods: The study subjects were divided into Group I (Control) and Group II (Infertile). The impact of UV-A on sperm viability, nuclear integrity, chromatin maturity and DNA fragmentation (pre-and post-exposure) was evaluated using standard techniques. Antioxidant enzyme activity assays viz. Lipid Peroxidation (LPO), Superoxide Dismutase (SOD) and Catalase were also analysed. Statistical significance was considered at p < 0.05. Results: This study revealed significant decline in%viability in Group II after UV-A exposure when compared with pre-exposed Group I. The percent sperm with disrupted nuclear toroidal assembly significantly increased in infertile group after exposure, leaving the DNA vulnerable to damage. A significant elevation was observed in the percent immature forms correlated with the significant reduction in% halo formation (impaired nuclear chromatin decondensation) in both post-treated groups as compared to pre-treated groups, suggesting that disruption of sperm toroid triggers DNA damage. UV-A exposure resulted in increased LPO with decrease in antioxidant enzymes in these groups. The percent decline in viability, chromatin decondensation (halo) and antioxidant enzymes were higher in Group II than in Group I. In addition, the percent increase in disrupted toroids and immature chromatin in Group II suggested that the deleterious impact of UV-A on spermatozoa from the infertile group is significantly greater than that of fertile individuals. Conclusion: This study thus revealed that short term UV-A exposure adversely impacts spermatozoa of infertile males to a greater extent than that of the fertile group. Thus, specific awareness and precautions are imperative for occupationally exposed individuals.