Effect of Taurine Levels on Liver Lipid Metabolism: An In Vivo Study in the Rat

Abstract

Previous studies using guinea pigs and cats have shown that liver lipid composition is affected by intrahepatic taurine levels. The purpose of the present study was to determine whether this sulfonated amino acid could also affect lipid metabolism in the rat, an animal capable of synthesizing substantial amounts of taurine and used extensively in studies on lipid metabolism. Wide variations in the hepatic taurine content were induced by administering either 1% taurine or 1% guanidinoethane sulfonate in the drinking water for 2 weeks. These treatments increased and decreased taurine liver content, respectively, but did not affect either food or water intakes, or growth rates. The plasma concentrations of the major lipid classes in treated animals did not show any significant alteration in comparison to control animals, except for nonesterified fatty acid levels that were significantly lowered by guanidinoethane sulfonate administration. Taurine supplementation did cause a significant decrease in total hepatic lipid content that was attributable to the reduction of free and esterified cholesterol, triglyceride, and phosphatidylethanolamine hepatic concentrations. This same treatment slightly increased both bile flow and secretion of taurine-conjugated primary bile salts. In particular, the proportion of tauro-beta-muricholate significantly increased, whereas that of taurodeoxycholate greatly decreased. The administration of guanidinoethane sulfonate reduced both the bile flow and the secretion of taurine-conjugated bile salts and caused a significant alteration in the ratio between glycine- and taurine-conjugated bile salts. This did not occur after the treatment with taurine. Interestingly, we observed an inverse correlation between hepatic taurine levels and the proportion of either cholesteryl ester in hepatic lipids or taurochenodeoxycholate in biliary bile salts. These facts suggest that taurine hepatic levels influence mostly hepatic steroid metabolism, but they also affect the metabolism of other lipid classes.

The Restorative Effect of Taurine on Experimental Nonalcoholic Steatohepatitis

“…A previous study showed that a high-taurine diet had no effect on appetite, food consumption, or weight gain [15], which was also confirmed by this study. In our study, there was no significant difference between the taurine treatment group and the model group in weight gain.…”

Dietary Taurine Decreases Hepatic Secretion of Cholesterol Ester in Rats Fed a High-Cholesterol Diet

“…It has been reported that the addition of taurine to cholesterol-enriched diets as compared to those without taurine leads to a marked reduction in the concentration of cholesterol in the rat liver, especially cholesterol ester [11,12,26]. In the present studies, we confirmed that dietary taurine consistently lowered the hepatic concentrations of cholesterol ester, but not free cholesterol, in both strains of rats fed the high-cholesterol diets.…”

Taurine: Protective properties against ethanol-induced hepatic steatosis and lipid peroxidation during chronic ethanol consumption in rats

“…The high serum triglyceride levels in the alcohol + taurine treated animals suggests that triglycerides were either secreted out of the liver (Yan et al, 1993) or that extrahepatic sources were being mobilized. However, in the alcohol + taurine treated animals, the increased concentration of plasma triglyceride could be a consequence of increased hepatic release of lipoproteins in these animals (or increased mobilization from adipose tissue).…”