8-Nitroguanine immunoreactivity in the neuron of cerebrum and cerebellum of mice from each group. Little or no expression of 8-nitroguanine in brain tissue was observed in control group. Intensive expression of 8-nitroguanine was found in neuron cells in the cerebral cortex exposed to arsenic. Significantly elevated 8-nitroguanine immunoreactivity is observed in the granular cells of cerebellum of mice exposed to arsenic; 8-nitroguanine expression was primarily distributed in the nucleus. The density and number of 8-nitroguanine immunopositive cells were decreased in the cerebellum of mice administered both arsenic and taurine. Little or no 8-nitroguanine expression was observed in the cerebellum of control group. Bar: Cerebrum = 100 µm. Cerebellum = 200 µm.