Effect of Sub-chronic Arsenic Exposure on Expression of γ-Glutamylcysteine Synthetase (γ-GCS) and Oxidative Stress in Rats Brain

Objectives  To observe the effect of sub-chronic arsenic exposure on antioxidant ability and the expression of γ-glutamylcysteine synthetase (γ-GCS) in brain of rats, in order to discuss the mechanism of the damage in nerve system.

Methods  Forty SD rats (body weight:100g±20g; half male and half female)were randomly divided into four groups: one control group and three treated groups (treated with NaAsO₂ in drinking water at dosages of 2.4 mg/L, 12 mg/L and 60 mg/L, respectively). The level of arsenic in brain tissue was detected with ICP-OES; total antioxidant ability in brain tissue was tested by colorimetry;level of GSH in hippocampus was measured by trace test method; the expression of γ-GCS mRNA in hippocampus was checked by qRT-PCR technique; the expression of γ-GCS protein in hippocampus was observed by immunohistochemistry.

Results  There were no significant differencs on body weight of rats between the control and treated groups (P>0.05). The levels of arsenic in brain of treated groups were increased; the total antioxidant abilities in brain of treated groups were decreased, the level of GSH in hippocampus of treated groups were decreased, the expression of γ-GCS mRNA and γ-GCS protein in hippocampusof treated groups were down regulated (P<0.05).

Conclusions  Sub-chronic arsenic exposure in rats could induce oxidative damage in brain, induce oxidative stress and downregulate the expression of γ-GCS mRNA in hippocampus, thereby, reduce the level of GSH in hippocampus.