Proteome analysis on the mechanism of electroacupuncture in relieving acute spinal cord injury at different time courses in rats

OBJECTIVE: To observe the effect of electroacupuncture (EA) on the differentially expressed proteins in the spinal cord at different time courses after acute spinal cord injury (ASCI) in the rat, so as to study its underlying mechanism in im-proving spinal traumatic injury. METHODS: A total of 105 male SD rats were randomized into normal control, model-6 h, EA-6 h, model-24 h, EA-24 h, model-48 h, EA-48 h groups, with 15 cases in each. ASCI model was established by using modified Allen's method. EA (2 Hz, 2-5 mA) was applied to "Mingmen" (GV 4) and "Dazhui" (GV 14) for 30 min. The injured spinal cord tissue (T10 -T11) was collected 6 h, 24 hand 48 h after ASCI and EA treatment, weighted and stored under -80 degrees D till detection. Two-dimensional gel electrophoresis (2-DE) was used to separate total proteins of the spinal tissue, followed by protein extraction and quantitation, 2-D gel image analysis, matrix assisted laser desorption ionisation time-of-flight mass spectrometry (MALDI-TOF-MS), and databases-searching for identification of the differentially-expressed proteins. RESULTS: A total of 10 differentially expressed proteins were identified in the present study. At 6 h, compared with control group, of the 5 types of spinal differential proteins, 4 were upregulated in the expression after ASCI, and the rest one was downregulated; while after EA, ASCI-induced expression changes in 4 of the 5 differential proteins were reversed. At 24 h after ASCI, 7 types of differential proteins were identified. Compared with control group, 6 differential proteins were upregulated, and the rest one was downregulated in model group. Compared with model group, ASCI-induced expression changes in 6 of the 7 differential proteins were reversed by EA. At 48 h after ASCI, a total of 8 types of differential proteins were identified. Compared with control group, 6 differential proteins were upregulated in the expression, and the rest two downregulated in model group. Compared with model group, ASCI-induced expression changes in 5 of the 8 differential proteins were reversed by EA. Along with the increased time and treatment, 24 h vs 6 h, two more differential proteins were identified, i.e., nucleoside diphosphate kinase and triosephosphate isomerase 1 (TPI 1). 48 h vs 24 h, 3 more differential proteins were identified, i.e., dihydrolipoamide dehydrogenase, malate dehydrogenase 1, and glyceraldehyde-3-phosphate dehydrogenase (GAPDH); but two proteins disappeared, i.e., nucleoside diphosphate kinase, and ubiquitin-conjugating enzyme E2N. The identified differential proteins involving the effects of EA in regulating cellular energy metabolism, DNA repair, cellular generation, differentiation, apoptosis, etc. CONCLUSION: Proteome analysis indicates that in ASCI rats, some differentially expressed proteins involving energy metabolism, neuronal apoptosis reduction, protein-degradation inhibition may contribute to the effect of EA in repairing the traumatic spinal tissue.