Ataxias are characterized by aberrant movement patterns closely related to cerebellar dys-function. Purkinje cell axons are the sole outputs from the cerebellar cortex, and dysfunctionalactivity of Purkinje cells has been associated with ataxic movements. However, the synapticcharacteristics of Purkinje cells in cases of ataxia are not yet well understood. The nicotinamideantagonist 3-acethylpyridine (3-AP) selectively destroys inferior olivary nucleus neurons so itis widely used to induce cerebellar ataxia. Five days after 3-AP treatment (65 mg/kg) in adultmale Sprague-Dawley rats, motor incoordination was revealed through BBB and Rotarod test-ing. In addition, in Purkinje cells from lobules V—VII of the cerebellar vermis studied by theGolgi method, the density of dendritic spines decreased, especially the thin and mushroomtypes. Western blot analysis showed a decrease in AMPA and PSD-95 content with an increaseof the -catenin protein, while GAD-67 and synaptophysin were unchanged. Findings suggest alimited capacity of Purkinje cells to acquire and consolidate afferent excitatory inputs and anaberrant, rigid profile in the movement-related output patterns of Purkinje neurons that likelycontributes to the motor-related impairments characteristic of cerebellar ataxias.