ABSTRACT
Objective To research the toxicity of ethanol extracts from Poylgonum multiflorum Thunb (PMT) induced by endotoxin of Gram-negative bacteria lipopolysaccharide (LPS) in rat liver, and then investigate the hepatotoxicity mechanisms of PMT on immune inflammatory signal pathway Toll-Like receptor 4 (TLR4) -interferon regulated factor3 (IRF-3). Methods SD rats were randomly assigned into normal control, LPS (4 mg/kg), acetaminophen APAP (625 mg/kg), PMT 6 g/kg (PMT- L), PMT 12 g/kg (PMT-H), LPS+APAP and LPS+PMT-L/-H groups. The 4 groups later were injected LPS 4 mg/kg by caudal vein, after 2 h, the corresponding drugs were administered once a day for 7 consecutive days, respectively. The changes of weight of rats were observed every day. The tissue morphology of liver tissue of rats on 2 h, 14 h, 5 d, 8 d after administration were detected by hematoxylin-eosin staining respectively. Real time quantitative PCR (RT-qPCR) method and Western blotting were used to detect the expression of TLR4, TRIF and IRF3 in the TLR4 signaling pathway in liver cells. Results Two hours after the rat tail vein injection of LPS, the liver tiny granulomas of rats could be observed in LPS-induced groups, and then, the liver injury of rats in LPS group was gradually recovered. Eight Days after LPS induction, the liver tissue structure of rats in LPS group was clear and complete, but in LPS + APAP group and LPS + PMT 6 or 12 g/kg groups, the focal necrosis of hepatocytes, with inflammatory cell infiltration could be observed. The results of RT-qPCR and Western blotting showed that in oral administration of PMT groups, the expression of TLR4, TRIF and IRF-3 mRNA and protein in the liver cells had no significant change compared with the normal control group. But in 4 groups induced with LPS, the expression of TLR4, TRIF and IRF- 3 mRNA and protein in the liver cells were significantly higher than that of the normal control group and LPS group (P<0.05). Conclusion PMT can cause liver damage induced by LPS, the hepatotoxicity is related to the positive regulation of TLR4/IRF-3 signaling pathways, which is not related to the dosage of PMT. The results show that activating TLR4/IRF3 signaling pathway is one of the mechanisms of liver injury of PMT in rats induced by LPS.