Taurine attenuates the development of hepatic steatosis through the inhibition of oxidative stress in a model of nonalcoholic fatty liver disease in vivo and in vitro.

Nonalcoholic fatty liver disease (NAFLD) is the most common cause of chronic liver disease. It is characterized by the accumulation of triglyceride within hepatocytes. Taurine is a sulfur-containing-ß-amino acid that is widely distributed in mammalian tissues. The objective of this study was to examine the effects of taurine on the development of hepatic steatosis in a model of NAFLD in vivo and in vitro. Male C57BL/6J mice were fed a high-fat diet (HFD) supplemented with 2% (w/v) or 5% (w/v) taurine for 12 weeks. An in vitro study was performed in HepG2 cells loaded with fatty acids. Twelve weeks of supplementation with an HFD increased the hepatic lipid levels and oxidative stress as well as the body weight and liver weight. Taurine significantly suppressed these changes, which was accompanied by a decrease in the hepatic level of thiobarbituric acid-reactive substances (TBARS). In addition, taurine treatment suppressed the HFD-induced reduction of the enzyme activity of hepatic superoxide dismutase and catalase and the reduction of the hepatic level of reduced glutathione and ATP. In HepG2 cells, taurine suppressed the fatty acid-induced lipid accumulation, production of reactive oxygen species and TBARS level, and amelioration of the fatty acid-induced disruption of the mitochondrial membrane potential. These results showed that taurine was effective in alleviating hepatic steatosis by reducing oxidative stress. Taurine may, therefore, be of therapeutic value in reducing the risks associated with NAFLD.

The Taurine Content of Japanese Seaweed.

Japanese and South Koreans have a dietary habit of eating seaweed. Although it is known that some seaweed contains taurine, there have been few detailed analyses on the taurine content of seaweed other than the major types of edible seaweed. In the present study, we determined the content of free amino acids, including taurine, in seaweed obtained along the Sea of Japan coast. The taurine content in the seaweed varied according to the species. Among the 29 different types of seaweed that were studied, red algae contained relatively high concentrations of taurine. In contrast, the taurine content was low or undetectable in brown and green algae. The algal alanine level was relatively higher in brown sea algae, which was in sharp contrast to its taurine level. No clear trends were observed with regards to the distribution of the other free amino acids, including aspartic acid, glutamic acid, and phenylalanine. Considering the physiological role of taurine in cellular homeostasis, the algal taurine content may be associated with the growing environment. Taurine-rich red edible algae such as mafunori (Gloiopeltis tenax)/fukurofunori (Gloiopeltis furcata), kabanori (Gracilaria textorii), and ogonori (Gracilaria vermiculophylla) may be used to create functional foods that are rich in naturally occurring taurine.

[Anti-osteopenic effect of taurine: possible involvement of activated MEK-ERK-Cbfa1 signaling].

Previously we first noted that taurine (TR) has anti-osteopenic effect on low Ca diet-induced osteopenia in rats (1). Employing osteoblastic MC3T3-E1 cells, the mechanism of the anti-osteopenic effect was explored in vitro. TR (1 mM) was found to promote mineralization of extracellular matrices, without affecting alkaline phosphataase activity. Gel shift assay using 32P-labeled OSE2 (osteoblast-specific cis-element 2: the consensus sequence for Cbfa1, refer to 2) indicated that TR (1 mM) increased the nuclear localization of Cbfa1, just as TPH (1-34) (3,4) and bisphosphonates did (5). In addition, TR was found to stimulate ERK phosphorylation. PD98059, a MEK inhibitor, suppressed effects of TR on both Cbfa1 transactivation and ERK activation. The results strongly suggest that TR first activates intracellular MEK-ERK-Cbfa1 signaling system thereby promoting mineralization and finally leading to its bone anabolic action.