Dietary Taurine Enhances Cholesterol Degradation and Reduces Serum and Liver Cholesterol Concentrations in Rats Fed a High-Cholesterol Diet

Abstract

The effect of taurine on hypercholesterolemia induced by feeding a high-cholesterol (HC) diet (10g/kg) to rats was examined. When various amounts of taurine (0.25, 0.5, 1, 2.5, 5, 10, 20, 30, 40 or 50 g/kg diet) were supplemented to HC for 2 wk, serum total cholesterol gradually and significantly decreased in a dose-dependent manner and normalized at the dose of 10 g taurine/kg, compared with the control (cholesterol free) diet group. By contrast, serum HDL-cholesterol was elevated by taurine supplementation. The HC diet caused a significant decrease in the concentration of taurine in serum, liver and heart compared to that in the control group, and the effective dose of supplemental taurine to improve its reduction was 2.5 g/kg diet. In the hypercholesterolemic rats fed the HC diet, the excretion of fecal bile acids and hepatic cholesterol 7 alpha-hydroxylase (CYP7A1) activity and its mRNA level increased significantly, and the supplementation of taurine further enhanced these indexes, indicating an increase in cholesterol degradation. The abundance of mRNA for Apo A-I, one of the main components of HDL, was reduced by HC and recovered by taurine supplementation. Agarose gel electrophoresis revealed that, in hypercholesterolemic rats fed the HC diet, the serum level of the heavier VLDL increased significantly, but taurine repressed this increase and normalized this pattern. Significant correlations were observed between the time- and dose-dependent increases of CYP7A1 gene expression and the decrease of blood cholesterol concentration in rats fed the HC diet supplemented with taurine (time, r = -0.538, P < 0.01, n = 32; dose, r = -0.738, P < 0.001, n = 20). These results suggest that the hypocholesterolemic effects of taurine observed in the hypocholesterolemic rats fed the HC diet were mainly due to the enhancement of cholesterol degradation and the excretion of bile acid.

Dietary Taurine Reduces Hepatic Secretion of Cholesteryl Ester and Enhances Fatty Acid Oxidation in Rats Fed a High-Cholesterol Diet

“…The addition of taurine to a cholesterol-enriched diet, but not to cholesterol-free diets, has been reported to reduce serum and liver cholesterol concentrations, particularly those of cholesteryl ester, in rats (21). We have previously reported that addition of taurine to a diet enriched with cholesterol significantly ameliorated dietary cholesterol-dependent increases in serum and hepatic concentrations of cholesteryl ester of in rats (9).…”

Nutritional Regulation of Bile Acid Metabolism Is Associated with Improved Pathological Characteristics of the Metabolic Syndrome

“…From studies in rats, it is known that supplementing low fat, casein-based diets with rather high doses of glycine and/or taurine affects bile acid metabolism (29,70,71). Previously, we have reported that exchanging casein with a glycine-and taurine-rich protein source modulated BA metabolism in low fat fed rats (30).…”

“…Supplementing taurine (70,71) or glycine (70) at doses of 50 g/kg diet to casein-based atherogenic diets (containing 1wt% cholesterol and 0.25 wt% cholic acid) has previously been shown to increase fecal BA excretion in rats. Furthermore, the rats treated with the taurine-supplemented diet had higher liver glutathione (GSH) content, decreased liver cholesterol concentration, and higher cholesterol-7a hydroxylase (Cyp7a1) mRNA levels and enzyme activity (71). In this study, the SPH diet provided taurine (1.9 g/kg diet), whereas the casein diet was free of taurine.…”

Effects of Taurine Supplementation on Performance, Egg Quality, Blood Parameter and Liver Lipid and Lipid Peroxidation Levels of Laying Hens Fed High Fat Diet

“…또한, 타우린이 콜레 스테롤 및 지질대사에 미치는 영향에 관하여 활발한 연구가 진행되었다. 다양한 실험 동물을 대상으로 타우린은 기초 사 료를 급여한 고양이 (Cantafora et al, 1991)와 기니아피그 (Cantafora et al, 1986)의 경우 간의 중성지방 함량을 증가시켰으 나, 고지방 사료를 급여한 흰쥐 (Yan et al, 1993;Park and Lee, 1998;Yokogoshi et al, 1999;Yany et al, 2002)에서는 혈 청과 간의 총 콜레스테롤 및 중성지방 함량을 감소시켰고, 토끼 (Petty et al, 1990)에서는 지질 변화가 나타나지 않았다. 따라서 고지방 사료에 타우린의 첨가 효과는 실험 동물의 대상과 특성에 따라 지질대사에 미치는 영향이 다르게 나타 날 수 있다 (Militante and Lombardini, 2004 Means within a raw with no common superscripts differ significantly (P<0.05).…”