Co-exposure to fluoride and sulfur dioxide on histological alteration and DNA damage in rat brain.

Fluoride (F) and sulfur dioxide (SO2 ) are the two common environmental contaminants that are associated with neurotoxicity. The present study was conducted to explore individual and combined exposure effects of F and SO2 on histological alteration and DNA damage in rat brain. For this, male Wistar albino rats were exposed to sodium fluoride (100 mg/L NaF) and sulfur dioxide (39.3 mg/m3 ) individually and in combination for 8 weeks. Histological alteration in brain is evaluated by hematoxylin-eosin staining, showed shrunken neurons, darkly stained small nucleus and decreased cell numbers in F and SO2 exposed groups. The effect of F and SO2 on DNA damage was assessed by comet assay. The results showed an increase in ratio of tailing and tail length in F or/and SO2 administered rats. In addition, the proportion of grade II and III were also increased in individual and combined exposed groups. Compared with the individual exposure, the proportion the grade III was significantly high in combined exposure, suggesting a synergistic effect of F and SO2 . These results indicate that the brain was more susceptible to the toxic effects of F and SO2 . And combined exposure to these pollutants can lead more pronounced toxic effects on brain.