SummaryThe objective of this study was to clarify the relationship between the accumulation of S -adenosylhomocysteine (SAH) and the change in the SAH hydrolase activity in vitamin B 6 (B 6 ). Male Wistar rats were fed a control diet (control and pair-fed groups) or B 6 -free diet (B 6 -deficient group) for 5 wk. Although the SAH-synthetic activity of SAH hydrolase significantly increased in the B 6 -deficient group, SAH-hydrolytic activity of SAH hydrolase showed no significant difference in the liver among the three groups. On the other hand, SAH hydrolase mRNA in the liver did not show any significant change. Thus, the accumulation of SAH would be due to the increased SAH-synthetic activity of SAH hydrolase. The disturbed methionine metabolism by B 6 -deficiency, such as a significant increase of plasma homocysteine, might induce the activation of SAH hydrolase in the direction of SAH synthesis.
Vitamin B 6 (B 6 ) deficiency affects homocysteine metabolism, and this leads to hyperhomocysteinemia. In this study, we examined i) the effects of B 6 -deficiency and graduated levels of dietary methionine on homocysteine metabolism, and ii) the effects of fortified folate on homocysteine metabolism. In experiment 1, Wistar male rats were fed a control or a B 6 -deficient diet supplemented with L-methionine at a level of 3, 6, or 9 g/kg of diet for 5 weeks. The resulting plasma homocysteine levels in the B 6 -deficient groups increased in relation to the increase in dietary methionine level. Next, in experiment 2, rats were fed a control, B 6 -deficient, or folate enriched (10 mg pteroylmonoglutamic acid/kg) B 6 -deficient diet containing L-methionine at 9 g/kg for 5 weeks. Although the B 6 -deficient diet induced hyperhomocysteinemia, folate fortification ameliorated the plasma homocysteine concentration. Overall, our results indicate that folate fortification ameliorates the hyperhomocysteinemia induced by B 6 deficiency and supplemental methionine intake.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.