Comparative proteomics and correlated signaling network of rat hippocampus in the pilocarpine model of temporal lobe epilepsy

Abstract

In temporal lobe epilepsy (TLE), the seizure origin typically involves the hippocampal formation. The pilocarpine-induced TLE provides a model to investigate the molecular and functional characterization of epileptogenesis by mimicking the human epileptic condition. Here, we employed a 2-D gel-based proteomic technique to profile proteome changes in the rat hippocampus after pilocarpine treatment. Using MALDI MS and MS/MS, 57 differentially expressed proteins were identified, which were found either up-regulated and/or down-regulated at the two time points 12 h (acute period; Ap) and 72 h (silent period; Sp) compared with the control. These proteins can be related to underlying mechanism of pilocarpine-induced TLE, indicating cytoskeleton modification, altered synaptic function, mitochondrial dysfunction, changed ion channel, and chaperone. Five of the identified proteins, synaptosomal-associated protein 25 (SNAP25), synapsin-2 (SYN2), homer protein homolog 2 (HOMER2), alpha-internexin (INA), and voltage-dependent anion channel 2 (VDAC2) were investigated by semiquantitative RT-PCR, and SNAP25 and INA were further validated by Western blot and immunohistochemistry staining. Furthermore, association of these pilocarpine-induced proteins with biological functions using the Ingenuity Pathway Analysis (IPA) tool showed that nucleic acid metabolism, system development, tissue and cell morphology were significantly altered. IPA of the canonical networks indicated that six membrane proteins (e.g., SNAP25, SYN2, and HOMER2) participated in three biological networks as starting proteins. Our results offer a clue to identify biomarkers for the development of pharmacological therapies targeted at epilepsy.