In vivo genotoxic effects of mercuric chloride in rat peripheral blood leucocytes using comet assay

DNA damage induced by Mercuric chloride (HgCl2) in leucocytes of Wistar alb ino mate rats has been studied in vivo. The comet assay or the alkaline sin gle cell gel electrophoresis (SCGE) assay was used to measure the DNA damag e. The rats were administered orally with doses ranging from 0.0054, 0.0108 . 0.0216, 0.0432 to 0.0864 mg/kg body weight (b.wt.) of HgCl2. The assay wa s performed on whole blood at 24, 48, 72 h, 1st and 2nd week. The reason le ucocytes were used was to reflect biomarker studies in humans. A significan t increase in mean comet tail length indicating DNA damage was observed at all time intervals with HgCl2 except in 2nd week post treatment when compar ed to controls. The mean comet tail length revealed a clear dose dependent increase from 0.0054 to 0.0432 mg/kg b.wt. A maximum increase in mean comet tail length was observed at 0.0432 mg/kg b.wt. 24 h after treatment. From 48 h post treatment, the mean comet tail lengths of all the doses gradually decreased and by week 2 of post treatment, they had approached control lev els. pointing to repair of the damaged DNA. These findings suggest that the comet assay is a highly sensitive technique to study DNA damage caused by metals. (C) 2001 Elsevier Science Ireland Ltd. All rights reserved.