Abstract: Objective To examine the effect of subchronic exposure to arsenic(As)on levels of three monoamine neurotransmitters in brains of mice and to provide evidences for exploring mechanism of As-induced neurotoxicity. Methods Seventy Kunming mice were randomly divided into one control group(drinking water alone),three experimental groups(1,2 and 4 ppm As₂O₃),and two protection groups(4 ppm As₂O₃+150 mg/kg taurine and 4 ppm As₂O₃+45 mg/kg vitamin CVit C).As₂O₃ was given through drinking water for 60 days.The mice were decapitated and their brains were removed.Three monoamine neurotransmitters,including onrepinephrine(NE),dopanline(DA),and 5-hydroxy tryptamine(5-HT)in cerebellum of mice were measured by high-performance liquid chromatography(HPLC) with fluorescence detector. Results The concentrations of NE,DA,and 5-HT were 188.96 ng/g,45.30 ng/g,and 148.42 ng/g in the mice cerebellum of control group.The concentrations of NE,DA,and 5-HT in mice cerebellum were 92.65,12.36 ng/g,and 147.26 ng/g and 37.18 ng/g,9.44 ng/g,and 105.00 ng/g7 and 22.35 ng/g,7.40 ng/g,and 65.58 ng/g,respectively,in the 1,2,and 4 ppm As₂O₃ groups.Levels of these neurotransmitters were significantly lower in the cerebellum of the mice exposed to As than those in the controls(P<0.05).On the contrary,the concentrations of NE,DA,and 5-HT were 30.76 ng/g,7.23 ng/g,and 77.88 ng/g and 37.75 ng/g,12.54 ng/g,and 61.41 ng/g in the taurine and Vit C group,being significantly higher than those of the group exposed to As(P<0.05). Conclusion Subchronic exposure to As can decrease the concentrations of 5-HT,DA,and NE in cerebellum of mice.Co-administration of taurine or Vit C may protect against the decreased concentrations of monoamine neurotransmitters induced by As.