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目的:阐明低分子壳聚糖(LMCTS)对四氯化碳(CCl4)诱导大鼠肝纤维化的抑制作用,探讨其对Toll样受体4(TLR4)表达的影响,为开发临床治疗肝纤维化的天然候选药物奠定基础。方法:将72只雄性Wistar大鼠随机均分空白对照组、CCl4组(模型组)、甘利欣(DG)组和50、100及150mg·kg-1 LMCTS组(低、中和高剂量组)。除空白对照组外,其余5组大鼠腹腔注射40%CCl4植物油(1.75mL·kg-1),每周2次,共8周;空白对照组大鼠腹腔注射等量100%植物油。从第9周起,DG组及LMCTS组大鼠分别灌胃给予DG和LMCTS(每天1次,共4周)。实验结束后检测各组大鼠血清中丙氨酸氨基转移酶(ALT)、天门冬氨酸氨基转移酶(AST)和碱性磷酸酶(ALP)的活性,光镜下观察肝组织病理学改变,并采用RT-PCR和Western blotting法检测TLR4表达情况。结果:血清学指标,中和高剂量LMCTS组大鼠血清ALT、AST和ALP活性均低于模型组(P<0.05);与低剂量LMCTS组比较,中剂量LMCTS组ALP活性明显降低(P<0.05),而ALT和AST活性降低不明显(P>0.05);高剂量LMCTS组ALT、AST和ALP活性与中剂量LMCTS组比较差异有统计学意义(P<0.05)。HE染色,模型组大鼠部分肝细胞脂肪变性,有明显的炎性细胞浸润和胶原纤维增生,肝小叶破坏明显,而LMCTS组大鼠肝组织的变化有所减轻。RT-PCR和Western blotting法,与模型组比较,LMCTS组大鼠肝组织中TLR4表达水平降低(P<0.05或P<0.01),以高剂量LMCTS组最为明显,不同剂量组之间比较差异均有统计学意义(P<0.05)。结论:高剂量LMCTS具有良好的降低肝纤维化大鼠血清转氨酶活性和改善肝纤维化大鼠肝功能的作用,且此过程与TLR4表达水平降低有关。
Objective: To elucidate the inhibitory effect of low molecular chitosan (LMCTS) on carbon tetrachloride (CCl4) -induced hepatic fibrosis in rats and its effect on the expression of Toll-like receptor 4 (TLR4) Lay the foundation for naturalized alternative medicine. Methods: Seventy-two male Wistar rats were randomly divided into blank control group, CCl4 group (model group), Glycyrrhizin (DG) group and 50, 100 and 150 mg · kg -1 LMCTS groups (low, medium and high dose groups) . Except for the blank control group, the remaining 5 groups were intraperitoneally injected with 40% CCl4 vegetable oil (1.75mL · kg-1) twice a week for 8 weeks. The blank control group was injected with 100% vegetable oil by intraperitoneal injection. From Week 9, rats in DG and LMCTS groups were given gavage with DG and LMCTS respectively (once daily for 4 weeks). After the experiment, the activity of alanine aminotransferase (ALT), aspartate aminotransferase (AST) and alkaline phosphatase (ALP) in serum of each group were detected. The pathological changes of liver tissue were observed under light microscope , And the expression of TLR4 was detected by RT-PCR and Western blotting. Results: Serum ALT, AST and ALP activities of serum were lower in LMCTS group than in LMCTS group (P <0.05). Compared with low dose LMCTS group, ALP activity in LMCTS group was significantly lower (P < 0.05), while the ALT and AST activities were not significantly reduced (P> 0.05). The ALT, AST and ALP activities of high dose LMCTS group were significantly different from those of medium LMCTS group (P <0.05). In HE staining, some hepatocytes in the model group had steatosis, obvious infiltration of inflammatory cells and hyperplasia of collagen fibers, and obvious destruction of hepatic lobules. The changes of liver tissue in LMCTS group were relieved. Compared with the model group, the expression of TLR4 in the LMCTS group was lower than that in the model group (P <0.05 or P <0.01) by RT-PCR and Western blotting, and the most obvious was the high dose LMCTS group There was statistical significance (P <0.05). CONCLUSION: High dose LMCTS has a good effect of reducing serum aminotransferase activity and improving hepatic function of hepatic fibrosis in rats with hepatic fibrosis, and the process is related to the decrease of TLR4 expression.