Alzheimer's disease (AD) is a common and devastating disease and there is no readily available biomarker to aid diagnosis or monitor progression of it. To further understand the pathogenic mechanism of AD, proteomic approach was used to study the cerebral synaptosomes proteins of rats injected with Abeta1-40. Compared with the untreated samples, 14 proteins were found apparently altered through 2-dimensional gel electrophoresis. 12 of them were down-regulated and 2 were up-regulated. Three proteins including alpha-2-globin chain, peptidyl-prolycis-trans isomerase A (PPIaseA) and cofilin-1 protein were identified by matrix-assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF-MS) and SWISS-PROT database query. Alpha-2-globin chain has not been shown to be associated with AD. PPIaseA and cofilin-1 protein are correlated with cell apoptosis and signaling. The altered proteins identified may help to understand the pathogenesis of AD.