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BACKGROUND: The use of fluorescent two-dimensional difference gel electrophoresis (2D-DIGE) has been shown to compensate for the shortcomings of conventional two-dimensional gel electrophoresis, such as poor repeatability and large systematic errors. However, little information is presently available regarding the use of 2D-DIGE to investigate mechanisms of ischemic cerebrovascular diseases. Plasma and body fluids have been utilized in proteomic technology to study ischemic cerebrovascular diseases.OBJECTIVE: To perform proteomic analysis of fresh rat brain tissue in peripheral ischemic regions using 2D-DIGE 6 hours after middle cerebral artery occlusion (MCAO), and to identify specific proteins closely associated with early ischemic cerebrovascular diseases. DESIGN, TIME AND SETTING: Proteomics-based, randomized, controlled, animal experiment was performed at the Laboratories of Neurology and Proteomics, Jilin University between January and April 2006.MATERIALS: 2, 3, 5-triphenyl tetrazolium chloride was purchased from Sigma, USA. Ettan DALTSix system, DeCyder DIA V5.0 differential analysis software, and Ettan matrix-assisted laser desorption/ionization time-of-flight mass spectrometer (MALDI-TOF-MS) were purchased from Amersham Bioscience, Sweden.METHODS: Eight healthy, male, Wistar rats were randomized to experimental and control groups, with four rats in each group. In the experimental group, rat models of focal cerebral ischemia were established by MCAO. In the control group, the internal and external carotid arteries were exposed and then immediately sutured, and the remaining procedures were identical to the experimental group. MAIN OUTCOME MEASURES: At 6 hours after cerebral ischemia, protein expression in the peripheral ischemia region of the experimental group was compared with the control group using 2D-DIGE. Protein spots that exhibited statistical differences between experimental and control groups with > 1.4 attributable risk were screened using DeCyder DIA V5.0 differential analysis software. Differential proteins were identified using MALDI-TOF-MS.RESULTS: Triphenyl tetrazolium chloride staining results revealed pink, normal brain tissue and white, ischemic brain tissue, suggesting successful MCAO establishment. The average matching rate of four 2D-DIGE gels was 92.4%. There were (1 758 ± 43) protein spots on each gel, with similar distribution modes. At 6 hours after focal cerebral ischemia, 13 protein spots exhibited marked expression changes, including significantly increased (n = 7) and decreased (n = 6) expression (P< 0.05). MALDI-TOF-MS results revealed two differential protein spots: a-tubulin and heat shock protein 27, which were significantly decreased in the experimental group compared with the control group (P < 0.05).CONCLUSION: Thirteen protein spots with expression changes were revealed by 2D-DIGE proteomics technology. Of them, a-tubulin and heat shock protein 27 expressions were markedly decreased during the early stage of cerebral ischemia. These two proteins were presumed to be proteins associated with early ischemic cerebrovascular diseases.