Effects of dietary cholestyramine and conjugated bile acids supplementation on the enzyme activities involved in taurine biosynthesis and gallbladder bile acid levels in bluegill Lepomis macrochirus
2019
Goto, T. (National Institute of Technology, Numazu College, Numazu, Shizuoka (Japan). Department of Chemistry and Biochemistry) | Kikuchi, T. | Harada, T. | Yanagisawa, M. | Kuwahara, T. | Tanaka, Y. | Ichihashi, A. | Endou, N.
In order to investigate the relationship between biliary bile acid levels and taurine biosynthesis in fish, bluegill Lepomis macrochirus was fed on the diets containing different levels of cholestyramine and 0.4% of taurine or glycine-conjugated bile acid for 30 and 22 days. At the end of each experiment, activities of hepatic enzyme involved in amino acid metabolism including taurine biosynthesis and muscular taurine and biliary bile acid levels were determined. Feeding of cholestyramine significantly reduced gallbladder bile acid content at a dose dependent manner, but cysteinesulfinate decarboxylase activity, a key enzyme of taurine biosynthesis, remained unchanged. Hepatic alanine aminotransferase decreased inversely in proportion to the cholestyramine intake. Supplementation of conjugated bile acids trended to result in lower body weight, probably due to their poor palatability, but each bile acid was found as a predominant component in gallbladder bile acid of the fish. However, cysteinesulfinate decarboxylase activity was not affected by the bile acid ingestions in this trial. Our present data indicate that change of biliary conjugated bile acid level does not influence taurine biosynthesis in bluegill. It seems that taurine and its conjugated bile acids firstly play an excretion form in cholesterol and sulfur amino acid in this fish.
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