Dietary fatty acids regulate cholesterol induction of liver CYP7α1 expression and bile acid production

In the present study we investigated the effects of dietary fats containing predominantly PUFA, monounsaturated FA (MUFA), or saturated FA (SFA) on lipid profile and liver cholesterol 7(x-hydroxylase (CYP7 alpha 1) mRNA expression and bile acid production in C57BL/6J mice. The animals (n = 75) were randomly divided into five groups and fed a basic chow diet (AIN93G) (BC diet), a chow diet with 1 g/1 00 g of cholesterol (Choi diet), a chow diet with I g/1 00 g of cholesterol and 14 g/1 00 g of safflower oil (Choi + PUFA diet), a chow diet with 1 g/l 00 g of cholesterol and olive oil (Cho[ + MUFA diet), or a chow diet with I g/l 00 g of cholesterol and myristic acid (Choi + SFA diet) for 6 wk. The results showed that the Choi + SFA diet decreased CYP7a1 gene expression and bile acid pool size, resulting in increased blood and liver cholesterol levels. Addition of PUFA and MUFA to a I % cholesterol diet increased the bile acid pool production or bile acid excretion and simultaneously decreased liver cholesterol accumulation despite decreased CYP7 alpha 1 mRNA expression. The results indicate that the decreased bile acid pool size induced by the SFA diet is related to inhibition of the liver CYP7 alpha 1 gene expression, but an increased bile acid pool size and improved cholesterol homeostasis are disassociated from the liver CYP7 alpha 1 gene expression.