Sericin is a protein component of the silkworm cocoon, and contains a high proportion of L-serine, but it has been mostly disposed of as an industrial waste. However, recent studies have revealed its unique biological functionalities beneficial to human health. This study aimed to evaluate the effect of acute oral intake of sericin on amino acid and neurotransmitter metabolism in the mouse brain. Acute administration of chemically modified sericin (0.26 g/30 g body weight) increased L-serine and L-tyrosine levels in the serum and brain, although the L-tyrosine content in the sericin was less than 3% (w/w). In addition, sericin administration led to a significant facilitation of noradrenergic turnover via enhancement of 3-methoxy-4-hydroxyphenylethyleneglycol, a principal metabolite of noradrenaline, in several of the brain regions examined. These present findings suggest that oral intake of sericin efficiently delivers L-serine and L-tyrosine to the brain, thus stimulating noradrenergic activity in the brain.Abbreviations: DA: dopamine; 5-HIAA: 5-hydroxyindoleicetic acid; 5-HT: 5-hydroxytryptamine; HVA: homovanillic acid; MHPG: 3-methoxy-4-hydroxyphenylethyleneglycol; 3-MT: 3-methoxytyramine; NA: noradrenaline; NM: normetanephrine; Veh: vehicle.

中文翻译：

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蚕丝丝胶的摄入会导致小鼠大脑中L-丝氨酸和L-酪氨酸水平的升高，同时促进大脑去甲肾上腺素的转换。

丝胶蛋白是家蚕茧的蛋白质成分，并含有较高比例的L-丝氨酸，但大部分已作为工业废料处理。但是，最近的研究表明其独特的生物学功能有益于人体健康。这项研究旨在评估口服水溶蛋白对小鼠大脑中氨基酸和神经递质代谢的影响。急性给予化学修饰的丝胶（0.26 g / 30 g体重）可以增加血清和大脑中L-丝氨酸和L-酪氨酸的水平，尽管丝胶中L-酪氨酸的含量低于3％（w / w）。另外，在检查的几个大脑区域中，丝胶蛋白的给药通过增强3-去甲肾上腺素的主要代谢物3-甲氧基-4-羟基苯基乙二醇，极大地促进了去甲肾上腺素的转换。这些目前的发现表明口服摄取丝胶可有效地将L-丝氨酸和L-酪氨酸释放到大脑，从而刺激大脑中的去甲肾上腺素能活动。5-HIAA：5-羟基吲哚乙酸；5-HT：5-羟基色胺；HVA：高香草酸；MHPG：3-甲氧基-4-羟基苯基乙二醇；3-MT：3-甲氧基酪胺；NA：去甲肾上腺素；NM：去甲肾上腺素；Veh：车辆。