[Mechanism of tetramethylpyrazine intervention with ischemia-reperfusion rats based on Nrf2/HO-1/CXCR4 pathway...

This study aims to decipher the mechanism of tetramethylpyrazine(TMP) in regulating the migration of neural stem cells(NSCs) in the rat model of middle cerebral artery occlusion(MCAO) via the nuclear factor erythroid 2-related factor 2(Nrf2)/heme oxygenase 1(HO-1)/C-X-C motif chemokine receptor 4(CXCR4) pathway. SD rats were randomized into sham, MCAO(model), and tetramethylpyrazine(TMP, 20 mg·kg~(-1) and 40 mg·kg~(-1)) groups. The neurological impairment was assessed by the modified neurological severity score(mNSS). The immunofluorescence assay was employed to detect the cells stained with both 5-bromodeoxyuridine(BrdU) and doublecortin(DCX) in the brain tissue. The effect of TMP on the migration of C17.2 cells was observed. Western blot was employed to determine the protein levels of Nrf2, HO-1, p62, NAD(P)H quinone oxidoreductase 1(NQO1), stromal cell-derived factor 1(SDF-1), and CXCR4 in the brain tissue and C17.2 cells. The results showed that after 7 days and 21 days of mode-ling, the mNSS and BrdU~+/DCX~+ cells were increased, and the expression of Nrf2 and CXCR4 in the brain tissue was up-regulated. Compared with the model group, TMP(40 mg·kg~(-1)) reduced the mNSS, increased the number of BrdU~+/DCX~+ cells, and up-regulated the expression of Nrf2, CXCR4, and SDF-1. In addition, TMP promoted the migration of C17.2 cells and up-regulated the expression of p62, Nrf2, HO-1, and NQO1 in a time-and dose-dependent manner. The expression was the highest at the time point of 12 h in the TMP(50 μg·mL~(-1)) group(P<0.01). In conclusion, TMP activates the Nrf2/HO-1/CXCR4 pathway to promote the migration of NSCs to the ischemic area, thus exerting the therapeutic effect on the ischemia-reperfusion injury. This study provides experimental support for the application of TMP in ischemic stroke.