Dietary taurine manipulations in aged male Fischer 344 rat tissue: taurineconcentration, taurine biosynthesis, and oxidative markers

Taurine (TAU) is a ubiquitous sulfur-containing amino acid that has been pr oposed to be an antioxidant. The concentration of TAU decreases during agin g, which may increase susceptibility to oxidative stress. Our study attempt ed to elucidate the mechanism for the age-dependent decrease in TAU content by examining TAU biosynthesis in aged rats. We also examined the effects o f dietary TAU manipulations on TAU content and oxidative markers in aged ma le Fischer 344 (F344) rats. Adult (9 months) and aged (26 months) rats fed control diets, aged rats fed control diet and TAU-supplemented (1.5%) water , and aged rats fed a TAU-deficient diet were used. We observed a significa nt age-related decrease in TAU content in liver, kidney, and cerebellum. Di etary TAU supplementation increased tissue TAU content, whereas dietary TAU restriction had no effect. Enzyme-dependent TAU synthesis showed an age-de pendent reduction in liver that was decreased further by TAU supplementatio n. Protein carbonyl content was elevated in the cerebral cortex and kidney of aged rats and was attenuated by TAU supplementation. A trend for a decre ase in protein and acid-soluble thiol contents in hepatic tissue of aged ra ts was observed, and this was attenuated with dietary TAU supplementation. Our data show that a decrease in hepatic TAU biosynthesis may cause, in par t, the observed decline in tissue TAU content in aged F344 rats, and TAU su pplementation can restore TAU levels. Our study indicates that a decline in TAU content may exacerbate oxidative stress in aged rats, which can be rev ersed by dietary TAU supplementation. (C) 2001 Elsevier Science Inc. All ri ghts reserved.