Neuroprotective Effect of Modified Xijiao Dihuang Decoction against Oxygen-Glucose Deprivation and Reoxygenation-Induced Injury in PC12 Cells: Involvement of TLR4-MyD88/NF-κB Signaling Pathway

Modified Xijiao Dihuang (XJDH) decoction has been shown to exert powerful neuroprotective properties in clinical ischemic stroke treatment. It consists of 4 Chinese herbs: Buffalo Horn, Paeonia suffruticosa Andrews, Rehmannia glutinosa (Gaertn.) DC, and Paeonia lactiflora Pall. In the present study, the neuroprotective effect and specific mechanisms of XJDH in protecting PC12 cells from oxygen-glucose deprivation-induced injury were investigated. It was found that OGD/R significantly decreased the cell viability and lactate dehydrogenase (LDH) activity and increased the release of IL-1β, IL-6, and TNF-α in PC12 cells, and these effects were suppressed by XJDH and one of its major active constituents, paeoniflorin. Additionally, XJDH inhibited caspase-3 activity and reduced cleaved caspase-3 level. Mechanistic studies showed that the expressions of TLR4, MyD88, TRAF6, and NF-κB p65 and phosphorylation of IκBα and p65 were significantly lower in the XJDH-treated group than in the OGD/R control group. Additionally, XJDH reversed the OGD/R-induced increases in p-JNK and p-ERK1/2 expression. These results suggest that XJDH protects PC12 cells from oxygen-glucose deprivation-induced injury, which may be associated with the inhibition of the TLR4-MyD88/NF-κB signaling pathway. As an anti-inflammation factor, XJDH might be used as a neuronal protection strategy for the ischemia injury and related diseases.