To investigate the protective effect of Tongqiao Huoxue Decoction containing cerebrospinal fluid(TQHXD-CSF) on HT22 cells damaged by oxygen-glucose deprivation/reoxygenation(OGD/R) and whether the mechanism is related to the regulation of ASK1/MKK4/JNK signaling pathway. HT22 cells were subjected to OGD/R to simulate cerebral ischemia-reperfusion injury(CIRI). Then the cells were randomly divided into five groups: blank cerebrospinal fluid(control group), OGD/R group, TQHXD-CSF group, Z-VAD-FMK group(20 μmol·L~(-1)) and TQHXD-CSF+Z-VAD-FMK group. Except the control group, cells in the other groups were reoxygenated for 12 h after 6 h of oxygen and glucose deprivation for modeling OGD/R, and group administration was performed. Cell viability and cytotoxicity were detected by CCK8 and LDH assay kit, respectively and the morphology of HT22 cells was observed by inverted microscope. Western blot and qRT-PCR were employed to detect the protein and mRNA expression levels of Bax, Bcl-2 and caspase-3, respectively. Then HT22 cells were assigned into the control group, OGD/R group, si-NC group, si-ASK1 group, TQHXD-CSF group and TQHXD-CSF+si-ASK1 group. Cell viability, proliferation and apoptosis were determined by CCK8, electric cell-substrate impedance sensing(ECIS), and Hoechst staining and flow cytometry, respectively. The protein expression of MKK4, p-MKK4, JNK, p-JNK, c-Jun, p-c-Jun, Cyt C, Bax, Bcl-2 and caspase-3 was tested by Western blot. The results showed that compared with OGD/R group, TQHXD-CSF significantly enhanced cell viability, improved cell morphology and reduced the protein and mRNA expression levels of Bax, Bcl-2 and caspase-3. In addition, when ASK1 was silenced, compared with OGD/R group, TQHXD-CSF remarkably improved cell viability, and decreased apoptosis rate and the protein expression levels of p-MKK4, p-JNK, p-c-Jun, Cyt C, Bax/Bcl-2 and caspase-3, but the effect was not as good as that of TQHXD-CSF+si-ASK1 group. In conclusion, TQHXD-CSF can inhibit apoptosis mediated by ASK1/MKK4/JNK signaling pathway in OGD/R-damaged HT22 cells, and has protective effect on ischemia-reperfusion injury.
Keywords: HT22 cells; Tongqiao Huoxue Decoction; apoptosis; cerebrospinal fluid; oxygen-glucose deprivation/reoxygenation.