Suppression of Methionine-Induced Hyperhomocysteinemia by Glycine and Serine in Rats

Abstract

The hyperhomocysteinemia induced by a dietary addition of 1% methionine was significantly suppressed by the concurrent addition of 1% glycine or 1.4% serine to the same degree. The methionine-induced increase in the hepatic concentration of methionine metabolites was significantly suppressed by glycine and serine, but the hepatic cystathionine -synthase activity was not enhanced by these amino acids. When the methioninesupplemented diet was changed to the methionine plus glycine or serine diet, the plasma homocysteine concentration rapidly decreased during and after the first day. The hyperhomocysteinemia induced by an intraperitoneal injection with methionine was also suppressed by concurrent injection with glycine or serine, although the effect of serine was significantly greater than that of glycine. These results indicate that glycine and serine were effective for suppressing methionine-induced hyperhomocysteinemia: serine and its precursor glycine are considered to have elicited their effects mainly by stimulating cystathionine synthesis by supplying serine, another substrate for cystathionine synthesis.

Effect of Dietary Supplementation with Folate on Choline Deficiency-Induced Hyperhomocysteinemia in Rats

“…Hence, in the present study, we used folate at a level of 20 mg/kg diet, which is considered to be the maximal dose within the nutritional range. On the other hand, in the present study, we used serine at a level of 2.5% according to our previous study showing that dietary supplementation with 2.5% serine completely suppressed methionine-induced hyperhomocysteinemia (31). The serine contents of 10C and 25S were estimated as 0.47 and 0.95%, respectively.…”

Effects of Various Amino Acids on Methionine-Induced Hyperhomocysteinemia in Rats

“…4) The result that methionine-induced increases in the hepatic concentra- Each value is the mean AE SEM for 5 (25C), 10 (25CM), or 4 (other groups) rats. 25C, 25% casein diet; 25CM, 25C + 1% Lmethionine diet.…”

“…Verhoef et al 3) have found that serine and cystine suppress the enhancement of plasma homocysteine concentration due to a single ingestion of a methionine-supplemented low-protein meal in humans. In addition, we found that dietary supplementation with glycine and with serine suppresses methionine-induced hyperhomocysteinemia in rats, 4) but little information is available on the effects of amino acids other than glycine, serine, and cystine on plasma homocysteine concentration.…”

Suplementação De Creatina, Homocisteína E Estresse Oxidativo

“…Ainda assim, autores apontam algumas controvérsias quanto aos clássicos estudos realizados por Mudd e Pole 36 e Mudd et al 37 e sugerem que a síntese de creatina pode não ser a maior responsável pelas reações de metiltransferases, apontando a biossíntese de fosfatidilcolina como importante determinante da demanda de metilação e consequentemente significante na produção de Hcy 56 . Além disso, estudos recentes têm demonstrado que outras importantes substân-cias podem modular o balanço de metilação e os ní-veis de Hcy como a betaína, glicina e serina 10,11 . Assim, mais estudos são necessários para quantificar a relativa contribuição dessas substâncias para as reações de metiltransferases, principalmente envolvendo a creatina.…”

“…Ainda, alguns autores têm voltado sua atenção ao estado vitamínico 7,8 e polimorfismos genéticos relacionados à HHcy 9 . Recentemente, estudos têm buscado entender o balanço da demanda de metilação e os efeitos da modulação de tal balanço sobre o metabolismo da homocisteína 4,10,11 . Contudo, o objetivo desta revisão é discutir os efeitos da suplementação com creatina sobre os níveis de homocisteína, além do seu possível papel protetor contra a formação de espécies reativas de oxigênio, das interações e inter-relações da ingestão com a produção endógena de creatina.…”