Objective To investigate the longterm neurotoxic effect of inflammation induced by intracerebroventricular injection of lipopolysaccharide (LPS) on dopaminergic neurons in the substantia nigra of rats，in order to explore the mechanism of inflammation in the progressive nature of Parkinson’s disease.Methods 28 healthy male SD rats were randomly assigned to 10μg, 25μg, 50μg LPSinjected groups and salineinjected group. All injections were made intracerebroventricularly on the right side with LPS or saline. Moving distance and speed were measured by Ethovison software. Tyrosine hydroxylase (TH)positive neurons and microglia were demonstrated by immunohistochemistry staining.Results Analysis of moving speed showed no significant difference between groups with 10μg, 25μg, 50μg of LPS and saline injections. The microglia were activated mostly in the brain in 10μg and 25μg LPSinjection groups, while the activation of microglia was not found in 50μg LPS and salineinjected rats. The TH-positive neurons in the substantia nigra of 10μg and 25μg LPS-injected groups decreased by 15.5% (P<0.01) and 20.1% (P<0.01) respectively, compared with those in the salineinjected group, but there was no significant differen