In vivo genotoxic effect of cadmium chloride in mice leukocytes using comet assay

The alkaline single cell gel electrophoresis (SCGE) or "comet" assay under alkaline conditions was used to measure DNA damage in the leukocytes of Swiss Albino male mice exposed to cadmium chloride (CdCl(2)). The effect of CdCl(2) was studied after a single acute oral administration of a range of doses starting from 0.5 to 128.0 mg/kg b.wt of CdCl(2). The samples of whole blood were collected from each mouse at 24, 48, 72, and 96 h post-treatment to study single/double strand breaks in DNA. A significant increase in mean comet tail length indicating DNA damage was observed with CdCl(2) at 24 h post-treatment (P<0.05) with CdCl(2) when compared to controls. A gradual decrease in the mean tail length was observed at 48 h post-treatment indicating repair of the damaged DNA. The mean tail length showed a dose-related increase and time-dependent decrease after treatment with CdCl(2) when compared to controls. The study also confirms that the comet assay is a sensitive and rapid method to detect DNA damage caused by heavy metal like Cadmium (Cd).

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 albino male rats has been studied in vivo. The comet assay or the alkaline single cell gel electrophoresis (SCGE) assay was used to measure the DNA damage. 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 was performed on whole blood at 24, 48, 72 h, 1st and 2nd week. The reason leucocytes were used was to reflect biomarker studies in humans. A significant increase in mean comet tail length indicating DNA damage was observed at all time intervals with HgCl2 except in 2nd week post treatment when compared 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 levels, 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.

In vivo genotoxic effect of potassium dichromate in mice leukocytes using comet assay

Hexavalent chromium is a well-known mutagen and carcinogen. In the present investigation, single-/double-stranded DNA breaks by potassium dichromate (K2Cr2O7) in mice, a sensitive model for genotoxic effects, have been studied in vivo using alkaline single-cell gel electrophoresis (SCGE)/comet assay. Mice were administered orally with a range of doses starting from 0.59 to 76.0 mg/kg body weight of K2Cr2O7 and samples of whole blood were collected at 24, 48, 72, 96 h, week 1 and week 2 post-treatment for alkaline SCGE assay to study DNA damage. The rationale for using leukocytes was to reflect biomarker analysis in humans. Significant increase in mean comet tail length (5.7-24.25 microM) indicating DNA damage was observed at all the doses with K2Cr2O7 when compared with controls (3.26 microM). Maximum increase in mean comet tail length was observed at 9.5 mg/kg body weight at 48 h post-treatment (24.25 microM). The mean comet tail length showed a clear dose-dependent increase from 0.59 to 9.5 mg/kg body weight and a dose-dependent decrease in higher doses (19.0-76.0 mg/kg body weight). A gradual decrease in the tail lengths from 72 h post-treatment was observed by the second week, and values had returned to control levels at all doses, indicating repair of the damaged DNA and/or loss of heavily damaged cells. The study also reveals that comet assay is a sensitive and rapid method for detecting DNA damage caused by heavy metals such as chromium (Cr).

In vivo genotoxic effect of zinc sulfate in mouse peripheral blood leukocytes using Comet assay

Single stranded DNA breaks induced by Zinc sulfate in mice has been studied in vivo using Alkaline Single Cell Gel Electrophoresis (Comet assay). Mice were administered orally with doses of 5.70, 8.55, 11.40, 14.25, 17.10 and 19.95 mg/kg body weight of zinc sulfate respectively. The samples of whole blood were collected at 24, 48, 72, 96 hr and first week post-treatment and the assay was carried out to determine single strand DNA breaks as represented by comet tail-lengths. Results indicated a significant DNA damage at all the doses after treatment with zinc sulfate when compared to controls showing a clear dose-dependent response (p < 0.05). A gradual decrease in the tail-lengths from 48 hr post-treatment onwards was observed indicating a time dependent decrease in the DNA damage. The study confirms that zinc sulfate causes significant DNA damage at the doses used as revealed by comet assay.

Genotoxic effect of lead nitrate on mice using SCGE (comet assay)

Single stranded DNA breakage induced by lead nitrate in mice has been studied in vivo using alkaline single cell gel electrophoresis (comet assay). Mice were administered orally 0.7, 1.4, 2.8, 5.6, 11. 2, 22.4, 44.8 and 89.6 mg/kg body weight of lead nitrate and the assay was performed on whole blood at 24, 48, 72 h, 1st and 2nd week. Significant increase in mean tail-length of DNA was observed at all time intervals after treatment with lead nitrate when compared to controls. The mean tail-length did not show a dose-related increase and the elevation in the mean tail-length was of a fluctuating type. Increase in mean tail-lengths clearly gives evidence that lead nitrate causes DNA damage effectively. The study indicates that the alkaline comet assay is a sensitive and rapid method to detect DNA damage caused by heavy metals.