Ovarian hormone deficiency-induced hypercholesterolemia is reversed by taurine

Abstract

The effect of taurine on plasma cholesterol and liver lipid levels, and on the level of fecal bile acid excretion, was examined in ovariectomized (ovx) 10-month-old retired breeder female rats. In the first experiment, ovx-rats were fed a casein-based cholesterol-free diet (C diet) or a C diet supplemented with different amounts of taurine (5 g, 10 g, 30 g and 50 g taurine/kg diet, respectively) for 21 days, and sacrificed at midnight in a fed state. Taurine reduced the ovx-induced increase in plasma total cholesterol level in a dose-dependent manner. Taurine increased the liver cholesterol level and level of fecal bile acids excretion in a dose-dependent manner. In the second experiment, ovx-rats were fed a C diet or a C diet supplemented with 50 g taurine/kg diet (C+50T diet) for 28 days, and killed at midnight in a fed state. The plasma total cholesterol, HDL-cholesterol, and LDL+VLDL-cholesterol levels of ovx-rats fed the C+50T diet were lower than the respective level of ovx-rats fed the C diet. There was a higher level of bile acids in the cecum of ovx-rats fed the C+50T diet than in the cecum of ovx-rats fed the C diet. In the third experiment, ovx-rats were fed the C diet for 8 days, then switched to the C+50T diet for the following 10 days, and then switched back to the C diet for 10 d. Blood samples were collected from the tail vein every two days between day 8 and day 28 at midnight in a fed state. The switch from the C diet to the C+50T diet resulted in a decrease in plasma cholesterol and an increase in fecal bile acid excretion. In contrast, switching from the C+50T diet to the C diet resulted in an increase in plasma total cholesterol and a decrease in fecal bile acid excretion. These data indicate that taurine can effectively prevent the ovarian hormone deficiency-associated increase in plasma cholesterol, and that an increased level of fecal bile acid excretion is one of factors involved in the hypocholesterolemic effect of taurine.