Abstract
We investigated the effects of 4.75% (w/w) branched-chain amino acid (BCAA) supplementation in rats fed a vitamin B6 (B6) -deficient diet. Five-week-old male Wistar rats were assigned to groups fed four different diets for 3 weeks as follows : 1) a 20% casein diet including sufficient B6 and non-supplemented BCAA (C group), 2) a B6-sufficient diet supplemented with BCAA (aaC group), 3) a B6-deficient diet of non-supplemented BCAA (D group), and 4) a B6-deficient diet supplemented with BCAA (aaD group). Half of the rats in the aaD group showed abnormal accumulation of triacylglycerols (TAG) in the liver. In the aaC group, serine dehydratase (SDH) activity was significantly higher than in the other three groups, and plasma levels of threonine, glycine and lysine were significantly lower than in the C group. We analyzed the statistical correlation between the parameters investigated in this study and the liver TAG content in the aaD group: this revealed negative correlations between the plasma levels of pyridoxal phosphate (PLP) and citrulline and liver SDH activity, and positive correlations with the plasma levels of threonine, glycine, tyrosine and lysine. These results suggest that a B6-sufficient diet supplemented with BCAA changes the amino acid metabolism of rats, and that a B6-deficient diet supplemented with BCAA causes multiple changes in amino acid metabolism accompanied by TAG accumulation in the liver of some rats.
