Formation of DNA Strand Breaks in Peripheral Lymphocytes of Rats After Exposure to Natural Sunlight.

Abstract: Objective: This paper aims to evaluate the genotoxicity in peripheral blood lymphocytes of rats after exposure to sunlight at different time points of day in a tropical region of Brazil (5°S, 42°W). Materials and Methods: Thirty Wistar-Hannover rats, three months old, were randomly divided into three groups of 10 animals each: Group I [control, without exposure to ultraviolet (UV) radiation], Group II (exposed to sunlight during 08:00 a.m. to 10:00 a.m.), and Group III (exposed to sunlight during 10:00 a.m. to 12:00 a.m.). After a week of exposure, peripheral blood samples were taken from the tail of these animals to prepare smears on two slides per animal. In 24 h after exposure to sunlight in Group III, a new collection was obtained to observe the repair activity. The alkaline comet assay was used in this study to evaluate the genotoxic activity of sunlight (P<0.05). Results: There was no statistical difference between Group I and II (P=0.672). On the other hand, the exposure to sunlight in Group III showed genotoxic action in comparison to the other groups (P<0.0001). Also, there was no significant repair in Group III R (P=0.407). Conclusion: This study has shown a genotoxic potential of sunlight (UVA-B) in lymphocytes of mammals from 10:00 a.m. to 12:00 a.m., due to a higher intensity of UV in this tropical region. [Copyright &y& Elsevier]