Protective effect of Sheng-jiang powder on nonalcoholic fatty liver disease induced by high fat diet through AMPK/mTOR signaling pathway in rats

Nonalcoholic fatty liver disease (NAFLD) has become a global public health problem, but its specific mechanism remains unclear and lacks effective therapeutic drugs. Sheng-jiang powder (SJP) has shown great potential for prevention and treatment of NAFLD in Chinese clinical reports, but the study of specific curative effects and mechanisms are still lacking. The purpose of this study was to observe the effect of SJP on high fat diet-induced rat NAFLD and to explore its underlining mechanisms. After 4 weeks of normal diet or high-fat diet, SD rats were randomly divided into the following four groups and each was given intragastric administration: Normal control group, NAFLD group, Sheng-jiang powder group and Fenofibrate group. All rats were sacrificed after 4 weeks' gavage. Blood was used to detect serum triglyceride (TG), total cholesterol (TC), alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels. Homogenized liver tissue was used to determine liver TG and TC contents. HE staining and oil red O staining were performed to show liver pathological changes. AMP-activated protein kinase alpha (AMPK alpha), p-AMPK alpha, mammalian target of rapamycin (mTOR) and p-mTOR protein expression in liver tissue were tested by western blot. The results showed that SJP significantly reduced the body weight, serum TG level, TG and TC content in liver of NAFLD rats, and markedly improved hepatic steatosis. SJP increased the expression of p-AMPK alpha protein and decreased the expression of p-mTOR protein. These results indicate that SJP can improve serum lipid and hepatic steatosis in rats with NAFLD induced by high-fat diet, and its effect may be achieved through regulating AMPK/mTOR signal pathway, inhibiting lipid synthesis and reducing hepatic lipid deposition.