Shuangyu Tiaozhi Granule Attenuates Hypercholesterolemia through the Reduction of Cholesterol Synthesis in Rat Fed a High Cholesterol Diet

Shuangyu Tiaozhi Granule (STG) is composed of two kinds of Chinese medicinal herbs in dioscorea, which are used for managing cholesterol levels in patients with hypercholesterolemia in traditional Chinese medicine (TCM). However, the potential molecular mechanisms of administration of STG in hypercholesterolemia remain unknown. In this study, we investigated the effects of STG on hepatic cholesterol metabolism in high cholesterol (HC) diet-induced hypercholesterolemic rat models and simvastatin was used as a positive control. Male Sprague Dawley (SD) rats were fed general or HC diet, respectively. After 4 weeks of feeding, HC diet-induced hypercholesterolemic rats were fed HC diet, STG at 5% (w/w) or 10% (w/w) mixed in the HC diet, or HC diet combined with simvastatin gavages (4 mg·kg(−1)·d(−1)) for 4 or 8 weeks. STG treatment decreased body weight gain, liver weight ratio, serum lipids levels and hepatic lipids accumulation in rats fed a HC diet. Moreover, the effects of STG on decreasing body weight and lowering liver cholesterol levels were in dose- and time-dependent. Furthermore, STG or simvastatin treatment decreased the mRNA and protein levels of HMGCR and SREBP-2 in liver. The ACAT-2 and CYP7A1 mRNA expression were significantly decreased in HC diet supplemented with STG, while the mRNA levels of LDLR were markedly increased. STG attenuates hypercholesterolemia via inhibiting SREBP-2 signaling pathway activation and increasing hepatic uptake genes expression, providing a novel idea of TCM keeping cholesterol levels down for the clinical application.