Scope: This study investigated the interaction of dietary capsaicinoids with the mRNA and protein expressions of key receptors and enzymes involved in cholesterol metabolism in ovariectomized (OVX) rats.
Methods and results: Female Sprague-Dawley rats were subjected to sham operation or ovariectomy. The sham group and OVX control group were fed with high-cholesterol diets, whereas the treatment group (control diet containing 0.01% capsaicinoids) was fed with high-cholesterol plus 0.01% capsaicinoids diet for 21 days. Capsaicinoids significantly decreased the body weight gain, plasma total cholesterol, LDL cholesterol, and triacylglycerol without affecting the high-density lipoprotein cholesterol in the OVX rats. The change in plasma lipoprotein profile was accompanied by a greater excretion of total bile acid in feces and small intestinal contents. Western blot and real-time PCR analyses revealed that capsaicinoids significantly enhanced the expressions of hepatic cholesterol 7α-hydroxylase and transient receptor potential vanilloid type-1 but did not affect the expression of 3-hydroxy-3-methylglutaryl-CoA reductase in the OVX rats.
Conclusion: Capsaicinoids have cholesterol-lowering effects in OVX rats. The hypocholesterolemic activity of capsaicinoids is caused by the stimulating conversion of cholesterol to bile acids by upregulation of cholesterol 7α-hydroxylase expression and the increase in fecal total bile acid excretion.
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