Preventive And Therapeutic Effect Of Berberine On Nonalcoholic Fatty Liver Disease Rats

Objective1. To evaluate the preventive and therapeutic effect of berberine on nonalcoholic fatty liver disease (NAFLD) rats induced by high-fat diet.2. To investigate the expression of tight junction protein Occludin in intestinal epithelial cells and to analyze its relationship with tumor necrosis factor-α(TNF-α) level in rats with NAFLD.MethodsSeventy-five male SD rats were divided into three groups: Group A (control group),fifteen rats were fed with normal diet; Group B (high fat group),forty-five rats were fed with high fat diet; Group C (prevention group) with fifteen rats were fed with high fat diet and administered with berberine 150mg/kg daily. After 8 weeks, three rats randomly selected from the high fat group and one from the control group were sacrificed. HE staining of liver tissue in model group showed that the NAFLD was established. Group B were fed with high fat diet consecutively and were randomly divided into 3 groups: The therapeutic groups were administered with berberine 250 mg/kg(B2) and 150mg/kg(B3) daily respectively while model goup (B1)with Normal Saline. Group A and C kept the original program. All the rats were sacrificed four weeks later. ALT,AST,TC,TG were assayed. The serum of TNF-αlevels were detected by radioimmunoassay. Liver tissue histological changes were observed under light microscopy after HE staining. Expression of TNF-αin hepatic cell were detected by immunohistochemistry. Occludin in intestinal epithelial cells was detected by immunohistochemistry. Intestinal epithelial tight junctions were observed by electron microscopy.Results1. Serum TNF-αlevel in the model group was significantly higher than that in the control group (3.21μg/L±0.45μg/L vs 2.10μg/L±0.29μg/L, t = -6.157, P < 0.01). In the model group, TNF-αwas mainly distributed in the cytoplasm of liver cells, presenting with brownish-yellow fine granules, whereas only scattered positive cells were seen in the control group.2.Immunohistochemistry analysis showed that Occludin was localized to the apical region of the intestinal lateral plasma membrane and distributed in a continuous pattern in the control group but significantly down-regulatedand distributed in a non-continuous pattern in the model group.3.Electron microscopy analysis demonstrated that tight junctions were significantly shorter in the model group than in the control group (0.50μm±0.21μm vs 0.78μm±0.19μm, P < 0.05).4.Compared to the control group, the body weight,liver weight,liver index and serum level of ALT,AST,TC,TG,TNF-αof model group were significantly elevated(P < 0.01).5.Compared to the model group, the body weight,liver weight and liver index of therapeutic and prevention groups were decreased, but had no significant difference. Serum level of ALT,AST,TC,TG,TNF-αwere significantly decreased compared with the model group(P<0.05). There was no significant difference between the preventive and therapeutic groups or compared to the control group. Immunohistochemistry showed that the expression of TNF-αin hepatic cell was decreased in preventive and therapeutic group compared to the model group.Conclusions1.Berberine can protect rats from NAFLD induced by high-fat diet. Meanwhile, berberine can decrease the expression of TNF-αboth in serum and in fatty liver cells, which may be one of the mechanism that preventing and treating high-fat diet-induced NAFLD rats.2. TNF-αmay inhibit the expression of tight junction protein Occludin in intestinal epithelial cells, which may result in intestinal barrier dysfunction and promote the development and progression of NAFLD.