Chinese soft-shelled turtle egg powder lowers serum cholesterol, increases faecal neutral steroids and bile acid excretion, and up-regulates liver cytochrome P450 mRNA level in rats

Abstract

The aim of the present study was to investigate the effect of Chinese soft-shelled turtle whole egg powder (TE) on cholesterol metabolism in Sprague-Dawley rats to determine whether it has a cholesterol-lowering effect. Forty male Sprague-Dawley rats were fed a high-fat diet supplemented with TE (0, 0.75, 1.50 or 3.00 g/kg body weight) administrated by gavage for 24 weeks. Serum total cholesterol (TC), HDL-cholesterol (HDL-C), LDL-cholesterol (LDL-C) and faecal total bile acids levels were determined by enzymatic methods. Faecal steroid concentrations were measured by GC. Means and standard deviations were calculated where appropriate for values, and the data were tested by one-way ANOVA. After 24 weeks of feeding a high-fat diet with TE supplementation, serum TC and LDL-C levels, liver cholesterol and liver lipid levels were reduced in rats. TE supplementation did not affect the faecal output, but significantly increased steroid concentrations in faeces, indicating increased steroids excretion. The faecal bile acid excretion was also increased as evidence by elevated mRNA level of liver cytochrome P450, family 7, subfamily A, polypeptide 1. Our results demonstrated that the TE does have a cholesterol-lowering effect by increasing the excretion of total bile acids and neutral steroids.