Protein expression profiling in the hippocampus after focal cerebral ischemia injury in rats.

In this study, we aimed to explore protein expression profiles in the hippocampus of rats after the induction of focal ischemia injury. Forty SD male rats were randomly divided into 4 groups, with ten rats per group: the control, Day 3, Day 7, and Day 14 after the ischemia injury surgery. Focal cortical ischemia was induced in thirty rats by photothrombosis of the cortical microvessels. After surgery, the induction of ischemia was confirmed by the measurement of infarct size using 2,3,5-triphenyltetrazolium chloride (TTC) staining. In order to identify the differentially expressed proteins between the diseased and control sides of the hippocampus, a comparative proteome analysis was performed using isobaric tags for relative or absolute quantitation (iTRAQ) coupled with 2D LC-MS/MS analysis. We identified 4,081 proteins, 260 of which were non-redundant and showed differential expression between the three surgery groups and the control. The hierarchical cluster analysis indicated that the three surgery groups had markedly different expression patterns of these 260 proteins, including 160 upregulated and 80 downregulated proteins. A Gene Ontology (GO) analysis revealed 4,944 GO terms, among which myelin sheath and cell junction were the two most enriched items. In the KEGG pathway analysis, ribosome was the most abundant item. A Venn diagram showing the overlap of 25 of the differentially expressed proteins quantified from the four groups and the results from the KEGG pathway analysis suggested that Epstein-Barr virus infection was the most abundant item. In protein-protein interaction (PPI) network, a total of 223 interactive proteins were predicted and used to construct the PPI network. In conclusion, myelin sheath, cell junction, and Epstein-Barr virus infection were implicated in focal ischemia injury. Vimentin (Vim) and albumin (Alb) may be important proteins involved in focal ischemia injury.