Methyl parathion (MP) is an organophosphorus pesticide used worldwide,and it has been associated with a wide spectrum of toxic effects on organisms in the environment.This study investigated the changes in protein profile of enriched membrane fraction from zebrafish (Danio rerio) brain exposed to three concentrations (0.5,1 and 2 mg/L) of MP.Two-dimensional gel electrophoresis (2D-PAGE) revealed that the abundance of 21 protein spots was remarkably altered in response to MP exposure.By matrix-assisted laser desorption/ ionization time-of-flight mass spectrometry (MALDI-TOF MS/MS) and database searching,16 proteins were identified as membrane proteins,among which 8 proteins were down-regulated,while 8 were up-regulated.Furthermore,the expression levels of differential membrane proteins were validated by Western blotting and quantitative real-time PCR.These proteins are mainly involved in oxidative stress response,signal transduction,metabolism,protein synthesis and degradation,neuroplasticity and regeneration as well as synaptic transmission.These results may aid our understanding of the mechanism of MP-induced neurotoxicity and provide the possibility of the establishment of candidate biomarkers of MP.