Effect of dietary taurine on cholesterol 7.ALPHA.-hydroxylase activity in the liver of mice fed a lithogenic diet.

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

“…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. Although the exact mechanism involved in the altered metabolism of cholesterol by dietary taurine is not fully understood, it has been suggested that dietary taurine exerts serum and liver cholesterol-lowering effects through a decrease in a putative hepatic metabolic pool of cholesterol by increasing the conversion of cholesterol to bile acids through an elevated activity of 7·-hydroxylase [7][8][9][10][11][12][13][14]. On the other hand, with regard to a link between the hepatic concentration of cholesterol ester and its secretion rate by the rat liver, Fungwe et al [16] reported that increasing amounts of Yamamoto/Yoshitama/Sakono/Nasu/ Murakami/Fukuda cholesterol in the diets caused an accumulation of cholesterol ester in the liver in a dose-dependent manner, whereas the hepatic secretion rate of cholesterol ester is proportional to the cholesterol level accumulated in the liver.…”

“…In general, the serum cholesterol concentration remains relatively constant by controlling the influx of cholesterol from the liver and intestine into blood streams and its removal by the liver and peripheral tissues. It has been reported that rats fed diets containing taurine exhibited an increased conversion of cholesterol to bile acids through a stimulated activity of hepatic 7·-hydroxylase, a rate-limiting enzyme of bile acid synthesis [7][8][9][10][11][12][13][14] and an increased bile acid excretion into bile ducts and feces [6,12]. These altered cholesterol metabolisms by taurine feeding have been shown to lead to a decreased hepatic cholesterol pool size [11,12], and hence to an enhanced removal of cholesterol from the serum compartment by receptor-mediated mechanisms in the liver [15].…”

The potential usefulness of taurine on diabetes mellitus and its complications

“…In type 2 diabetic models, high myeloperoxidase activity has been found in the vessels of diabetic obese rats (Zhang et al 2004), indicating that HClO may contribute to increase in oxidized LDL in diabetes. Moreover, lowering effect of taurine on the production of LDL-cholesterol itself may contribute the reduction of oxidized LDL (Bellentani et al 1987; Gandhi et al 1992; Nakamura-Yamanaka et al 1987; Yokogoshi et al 1999). The increased serum level of LDL cholesterol in STZ-treated diabetic mice was normalized by the chronic administration of taurine (Mochizuki et al 1999; Nanami et al 1996).…”

Effects of Long-Term Treatment with Taurine in Mice Fed a High -Fat Diet

“…The mechanism by which taurine decreases serum LDL and VLDL cholesterol, and increases HDL cholesterol remains elusive. Several investigations showed that taurine stimulates conversion of cholesterol to bile acid via elevation of cholesterol 7 -hydroxylase activity 13,18,21,34 . Conversion of cholesterol to bile acid represents the major regulated pathway whereby cholesterol is eliminated from the body 30 .…”

“…Thus, taurine attenuates abnormal cholesterol metabolism, and normalizes plasma and tissues cholesterol levels. Although the mechanism responsible for hypocholesterolemic action of taurine was not well defined, recent studies revealed that taurine stimulates cholesterol catabolism to bile acid by enhancing cholesterol 7 -hydroxylase activity, a rate-limiting enzyme for bile acid synthesis 13,18,21,34 . This event result in an increase in receptor-mediated LDL uptake and cholesterol synthesis in the liver.…”