Pien-Tze-Huang attenuates neuroinflammation in cerebral ischemia-reperfusion injury in rats partially through the TLR4/NF-κB/MAPK pathway

Background Pien-Tze-Huang (PTH), one of the most famous traditional Chinese medicines in China, is traditionally applied to treat various inflammation-related diseases including stroke. However, literature regarding the anti-inflammatory effects and possible mechanisms of PTH in ischemic stroke is unavailable. This study intended to investigate the anti-inflammatory effects of PTH against cerebral ischemia-reperfusion injury and clarify its potential molecular mechanisms. Methods Cerebral ischemia-reperfusion injury was induced through transient left transient middle cerebral artery occlusion (MCAO) in male rats receiving oral pretreatment with PTH (180 mg/kg) for 4 days. TLR4 antagonist TAK-242 (3 mg/kg) was injected intraperitoneally at 1.5 h after MCAO. Magnetic resonance imaging, hematoxylin–eosin staining, RT-PCR, western blot, and immunofluorescence methods were used to studied the effect and mechanism of PTH against ischemic stroke. Results PTH treatment reduced cerebral infarct volume, improved neurological function, and ameliorated brain histopathological damage in MCAO rats. In addition, it markedly suppressed a variety of inflammatory responses as evidenced by the reduced mRNA levels of IL-1β, IL-6, TNF-α and MCP-1; the inhibition of microglia and astrocyte activations; and the decreased protein expressions of iNOS and COX-2 in injured brains. Moreover, PTH down-regulated the protein expressions of TLR4, MyD88, and TRAF6; reduced the expression and NF-κB; and lowered the protein expressions of p-ERK1/2, p-JNK, and p-p38. Similar effects were observed in the TAK-242 treated group. However, TAK-242 did not significantly reinforce the anti-inflammatory effects of PTH. Conclusion PTH could attenuate neuroinflammation, improve neurological function, and alleviate brain injury in MCAO rats, and its potential mechanisms are partly connected to inhibition of neuroinflammation involving the TLR4/NF-κB/MAPK signaling pathway.