Abstract: ObjectiveTo examine the influence of subchronic arsenic (As) exposure on synapse ultrastructures and expressions of relevant genes in cerebiwn of mice.MethodsThirty mice were divided into three groups including two experinental groups(1 mg/L or 4mg/L As₂O₃)and one control As₂O₃ was given for consecutive 60 days, followed by decollation Changes of synapse ultrastructure and differential expressions of the relevant genes were examined with electron microscope and Gene Chip technique.ResultsIn controls, synaptic vesicle increased obviously within presynapse in cerebrum of the mice.Compared to the controls, synaptic vesicle decreased obviously within presynapse in cerebmm of the mice exposed to As In genechip screening, 10 differential expressions of the relevant genes were observed in experin ental groups Among these genes, Cam k4, Tac1, Drd1a and Drd2 were upregulated and Cp1x2, Cacna1a, Grin2b, Gan 7, AIs2 and Gan2 were down regulated.ConclusionSubchronic exposure to As may affect adversely synapse ultrastructure and expressions of relevant genes in cerebrum of mice.These results indicate that synapse in cerebrum may be a target of As-induced neurotoxicity.