Hypohomocysteinemic Effect of Cysteine Is Associated with Increased Plasma Cysteine Concentration in Rats Fed Diets Low in Protein and Methionine Levels

概要

論文の詳細を見る
Rats were fed diets with and without 0.5% L-cysteine supplement for 14d or shorter periods to clarify the mechanism by which dietary cysteine elicits its hypohomocysteinemic effect. Cysteine supplementation significantly decreased plasma homocysteine concentration with an increase in plasma cysteine concentration in rats fed 10% casein diet (10C) or 15% soybean protein diet (15S) but not in rats fed 25% casein diet (25C) or 25% soybean protein diet. Cysteine supplementation also significantly suppressed hyperhomocysteinemia induced by choline-deprived 10C with an increase in plasma cysteine concentration but not that induced by 25C+0.65% methionine or 25C+0.4% guanidinoacetic acid. Hepatic S-adenosylmethionine (SAM) and homocysteine concentrations were significantly decreased by cysteine supplementation of 15S. These decreases in plasma homocysteine concentration and hepatic SAM and homocysteine concentrations due to cysteine supplementation disappeared when 15S was fortified with 0.3% methionine. The plasma homocysteine concentration significantly decreased with an increase in plasma cysteine concentration only 1d after diet change from 15S to cysteine-supplemented 15S, while hepatic cystathionine β-synthase and betaine-homocysteine S-methyltransferase activities were not altered. Unlike cysteine, cysteic acid and 2-mercaptoethylamine did not decrease plasma homocysteine concentration. These results indicate that cysteine markedly decreases plasma homocysteine concentration only when added to diets low in both protein and methionine levels and suggest that increased plasma cysteine concentration and decreased flow of methionine toward homocysteine formation, but not alteration of homocysteine-metabolizing enzyme activities, are associated with the hypohomocysteinemic effect of cysteine.
日本ビタミン学会の論文

Hypohomocysteinemic Effect of Cysteine Is Associated with Increased Plasma Cysteine Concentration in Rats Fed Diets Low in Protein and Methionine Levels

スポンサーリンク

概要

著者

関連論文

スポンサーリンク