Study on the Lipid-regulating and Liver-protecting Effects of Flavonoids from Scutellaria Amoena and the Effects on the Activities of HMGCR and CYP7A1 in Liver Tissue

OBJECTIVE To study the effect of Scutellaria amoena flavonoids(SAF) on regulating lipid and protecting lilver and the activities of HMG-Co A reductase(HMGCR) and cholesterol 7α-hydroxylase(CYP7A1) in hyperlipidemia rats. METHODS Eight rats were randomly selected from 40 SD rats as the normal group, 32 hyperlipidemia model rats were induced by high-fat diet. After 8 weeks, hyperlipidemia rats were divided randomly into model group(saline), fenofibrate group(20 mg·kg^-1), SAF high and low dose groups(100, 20 mg·kg^-1), and 1 time per day for 4 consecutive weeks. Body weights was checked every week. At the end of the experiment, the contents of total cholesterol(TC), triglyceride(TG), low density lipoprotein cholesterol(LDL-C), high-density lipoprotein cholesterol(HDL-C), aspartate aminotransferase(AST), alanine aminotransferase(ALT) in serum and TC, TG in liver were measured. The histopathological changes of the liver tissues were observed by HE staining. The activities of HMGCR and CYP7A1 in the liver tissues were detected by ELISA. RESULTS Compared with the normal group, the results showed that the model group significantly increased body weight, and the levels of TC, TG, LDL-C, ALT and AST in serum, while HDL-C level was decreased(P<0.001). In liver tissue, steatosis was severe, and the levels of TC, TG and the activity of HMGCR were significantly increased, while the activity of CYP7A1 was significantly decreased(P<0.001). Compared with the model group, the results showed SAF high and low dose groups significantly reduced the levels of TC, TG, LDL-C, AST, ALT, while significantly increased the level of HDL-C in serum(P<0.05 or P<0.001). In liver tissue, the pathological changes were improved, and the levels of TC, TG and the activity of HMGCR were significantly reduced, while the activity of CYP7A1 was significantly increased after SAF administration(P<0.01 or P<0.001), especially in high dose group. CONCLUSION The SAF can significantly reduce blood lipid level of hyperlipidemia rats, while it can improve liver function. The mechanism might be related to the down-regulation of HMGCR level to inhibit cholesterol biosynthesis and the up-regulation of CYP7A1 activity to promote cholesterol metabolism, which regulate lipid metabolism disorder.