Soy peptide ingestion augments the synthesis and metabolism of noradrenaline in the mouse brain

To examine whether edible peptide intake affects neurotransmitter metabolism in the brain, we evaluated the effect of peptides derived from soy proteins or fish collagen on free amino acids and monoamines in the mouse brain. Ingestion of soy peptides led to markedly higher levels of tyrosine, a catecholamine precursor, in the serum, and cerebral cortex compared to those following ingestion of vehicle alone or collagen peptides. Soy peptide ingestion also effectively increased 3-methoxy-4-hydroxyphenylethyleneglycol and normetanephrine, the principal metabolites of noradrenaline, in the cerebral cortex, hippocampus, and brainstem, whereas collagen peptides did not exert such effects. Further, soy peptide ingestion led to a significant increase in noradrenaline itself in the brainstem, where noradrenergic neurons are present. Noradrenergic turnover was also markedly stimulated in these regions after soy peptide ingestion. These <i>in vivo</i> observations suggest that soy peptide ingestion can maintain and promote the synthesis and metabolism of noradrenaline in the brain. Soy peptide ingestion promotes the synthesis and metabolism of noradrenaline in the brain via increased Tyr availability.

为探究食用肽的摄入是否会影响大脑内神经递质代谢，本研究评估了大豆蛋白源肽与鱼胶原肽对小鼠大脑内游离氨基酸及单胺类物质的调控作用。与仅摄入赋形剂或胶原肽的对照组相比，摄入大豆肽可使血清及大脑皮层中的酪氨酸（儿茶酚胺前体）水平显著升高。此外，摄入大豆肽还可有效提升大脑皮层、海马体及脑干中去甲肾上腺素的主要代谢产物3-甲氧基-4-羟基苯乙二醇与去甲变肾上腺素的水平，而胶原肽则未表现出此类效应。进一步研究发现，摄入大豆肽可使存在去甲肾上腺素能神经元的脑干中，去甲肾上腺素自身的水平显著升高；同时上述脑区的去甲肾上腺素能代谢周转也显著增强。这些体内（in vivo）实验观察结果表明，摄入大豆肽可维持并促进大脑内去甲肾上腺素的合成与代谢。摄入大豆肽可通过提升酪氨酸的生物可利用性，促进大脑内去甲肾上腺素的合成与代谢。