title: 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 degrees S, 42 degrees W).
  
  
  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).
  
  
  CONCLUSIONS
  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.
authors.affiliation: Department of Biology, Federal University of Piaui-Teresina, Piaui, Brazil. dorivalmrjr@gmail.com
authors.forename: Dorival Mendes
authors.initials: DM
authors.lastname: Rodrigues-Junior
authors.forename: Ana Amélia de Carvalho
authors.initials: AA
authors.lastname: Melo
authors.forename: Benedito Borges
authors.initials: BB
authors.lastname: da Silva
authors.forename: Pedro Vitor
authors.initials: PV
authors.lastname: Lopes-Costa
mesh_terms: D000818:Animals; D020552:Comet Assay; D004249:DNA Damage; D008214:Lymphocytes / Q000528:radiation effects*; D051381:Rats; D017208:Rats, Wistar; D013472:Sunlight