Daming capsule, a hypolipidaemic drug, lowers blood lipids by activating the AMPK signalling pathway

Hyperlipidaemia is a major risk factor for cardiovascular and cerebrovascular diseases. Daming capsule (DMC), a medicine for lowering blood lipids, is marketed in China; however, its mechanism is unclear. The present study aimed to investigate the mechanism by which DMC reduces blood lipids.A rat model of hyperlipidaemia was established by feeding rats a high-fat diet (HFD), and the serum lipid levels were detected with an automatic biochemical analyser. DMC (162 mg/kg) and atorvastatin calcium (10 mg/kg) were orally administered to the hyperlipidaemic rats for 4 weeks. HFD feeding markedly induced increases in the levels of total cholesterol (TC), triglyceride (TG), and low-density lipoprotein cholesterol (LDL-c); however, DMC treatment significantly decreased the levels of TC, TG, and LDL-c in rats serum. Meanwhile, the hepatic TC and TG levels, liver weight/body weight ratio, and body weight were significantly lower in the DMC-treated rats than in the HFD rats. Moreover, DMC significantly alleviated hepatomegaly, hepatic lipid deposition, and hepatic steatosis. The protein expression level of phospho-adenosine monophosphate-activated protein kinase (p-AMPK) (Thr172) in HFD rat livers was lower than that in normal rat livers, whereas it increased in the liver of the DMC-treated rats; however, the protein expression level of total-AMPK in the liver was not different among the groups. The AMPK-activating effect of DMC was blocked by Compound C (a specific AMPK inhibitor) in HepG2 cells. Additionally, DMC considerably increased peroxisome proliferator-activated receptor-alpha (PPARα) protein expression and lipoprotein lipase (LPL) transcription and concentration in the liver. This effect of DMC was also inhibited by Compound C in HepG2 cells. DMC also promoted LDL receptor (LDLR) protein expression by activating AMPK. We further found that DMC reduced the levels of TC and TG in oleic acid-treated HepG2 cells, and it restored the expression levels of p-AMPK, PPARα, LPL, and LDLR compared to the decreased levels observed in oleic acid-treated HepG2 cells.DMC lowered lipids in serum and the liver by activating AMPK. On the one hand, the activation of AMPK enhanced PPARα expression and LPL transcription to lead to the hydrolysis of TG; on the other hand, it increased LDLR protein expression to promote lipid metabolism.