Lewy body inclusions enriched with aggregated forms of the presynaptic protein alpha-synuclein (aSyn) are a hallmark of synucleinopathy diseases such as Parkinson's disease (PD) and dementia with Lewy bodies (DLB). To model this pathology, Sprague-Dawley rats were injected in the striatum with preformed fibrils (PFFs) prepared from mouse aSyn to induce the aggregation of the endogenous mouse protein. Monomeric aSyn was injected as a control. Aggregated aSyn was detected via immunohistochemical staining in the sensorimotor cortex at 1- and 3-months post-injection in PFF-injected rats, but not monomer-injected animals. Global proteomics analysis was carried out on homogenates from the sensorimotor cortex of rats inoculated with PFFs or monomer, 3 months post-injection, and the data are presented here.