Hepatoprotective Effects Of Crude Glycyrrhiza Uralensis Polysaccharide On Non-alcoholic Fatty Liver Disease In Rats

Objective: Non-alcoholic fatty liver disease(NAFLD)is highly prevalent in the world.It is associated with insulin resistance(IR)and hyperlipidemia and is a predictor of numerous disease-related deaths.The purpose of our research was to investigate the protective effect of crude Glycyrrhiza uralensis polysaccharide(CGP)against NAFLD by high-fat diet(HFD)induced.Methods: We analyzed CGP using phenol-sulfuric acid method,ultraviolet spectrophotometry(UV),fourier transform infrared spectra(FT-IR),and high performance liquid chromatography(HPLC).Nonalcoholic fatty liver disease rat models by HFD induced were observed.A rat model of HFD-induced NAFLD was used to study the hepatoprotective effects of CGP.SD rats(n=52)were randomly divided into normal group and model group according to body weight,and normal feed and high-fat feed were fed respectively.After 10 weeks of continuous feeding,it was judged whether the model was successful.Then,the model group(n=48)rats were then randomly divided into CGP treatment group(400,500,600 mg/kg),metformin treatment group(150 mg/kg)and model group.After 6 weeks of intervention,serum total cholesterol(TC),triglycerides(TG),low-density lipoprotein cholesterol(LDL-C),high-density lipoprotein cholesterol(HDL-C),alanine aminotransferase(ALT),aspartate aminotransferase(AST),interleukin-6(IL-6),tumor necrosis factor-?(TNF-?),fasting blood glucose(FPG)and insulin levels were analyzed.Malondialdehyde(MDA),superoxide dismutase(SOD),catalase(CAT)and reduced glutathionease(GSH)were detected in rat liver tissue.At the same time,the liver was histopathologically examined.The protein and gene expression of cytochrome P4502E1(CYP2E1)in liver tissue were detected by RT-PCR and western blot.Results: The results indicated that CGP was a heteropolysaccharide that was mainly composed of mannose,rhamnose,glucose,fucose,and galactose at the molar ratio of 3.11: 5.45:13.6:0.22:0.53.It has the infrared and ultraviolet absorption characteristics of the polysaccharide,and the polysaccharide content is 42.81%.Compared with the model group,oral administration of CGP at different concentrations reduced the levels of TG,TC,ALT,AST,LDL-C,MDA,FPG,and insulin in serum of NAFLD rats.(P<0.05),and increased the levels of SOD,GSH,and CAT(P <0.05)in liver tissue of NAFLD rats.At the same time,CGP also inhibited the increase of serum TNF-? and IL-6(P<0.05)and improved the pro-inflammatory factor environment in NAFLD rats.The results of RT-PCR and Western blot showed that CGP inhibited the expression of CYP2E1 in liver tissue of NAFLD rats.In addition,histopathological examination showed that CGP treatment reduced fat infiltration and reversed histopathological changes in the liver tissue of NAFLD rats.Conclusion: The study showed that CGP can prevent nonalcoholic fatty liver by improving lipid metabolism and reducing oxidative stress damage in the liver tissue of NAFLD rats.Its possible mechanism of action is to lower blood lipids,increase insulin sensitivity and oxidative stress-related enzyme activities,improve inflammatory factors in serum of NAFLD rats and inhibit the expression of CYP2E1 gene.This study provides a theoretical basis for the development and application of licorice.