Key Laboratory of Tea Science of Ministry of Education, Hunan Agricultural University, Changsha 410128, China.
National Research Center of Engineering Technology for Utilization of Botanical Functional Ingredients, Hunan Agricultural University, Changsha 410128, China.
Nutrients. 2021 Nov 17;13(11):4120. doi: 10.3390/nu13114120.
Epigallocatechin gallate (EGCG) and L-theanine (LTA) are important bioactive components in tea that have shown promising effects on nutrient metabolism. However, whether EGCG alone or combined with LTA can regulate the glucose, lipid, and protein metabolism of healthy rats remains unclear. Therefore, we treated healthy rats with EGCG or the combination of EGCG and LTA (EGCG+LTA) to investigate the effects of EGCG on nutrient metabolism and the role of LTA in the metabolism-regulatory effects of EGCG. The results showed that compared with the control group, EGCG activated insulin and AMP-activated protein kinase (AMPK) signals, thus regulating glucose, lipid, and protein metabolism. Compared with EGCG, EGCG+LTA enhanced hepatic and muscle glycogen levels and suppressed phosphorylation of AMPK, glycogen synthase 2, mammalian target of rapamycin, and ribosomal protein S6 kinase. In addition, EGCG+LTA inhibited the expression of liver kinase B1, insulin receptor and insulin receptor substrate, and promoted the phosphorylation level of acetyl-CoA carboxylase. Furthermore, both EGCG and EGCG+LTA were harmless for young rats. In conclusion, EGCG activated AMPK and insulin pathways, thereby promoting glycolysis, glycogen, and protein synthesis and inhibiting fatty acid (FA) and cholesterol synthesis. However, LTA cooperated with EGCG to promote glycogen metabolism and suppressed the effect EGCG on FA and protein synthesis via AMPK signals.
没食子儿茶素没食子酸酯（EGCG）和 L-茶氨酸（LTA）是茶叶中的重要生物活性成分，它们对营养代谢显示出良好的效果。然而，EGCG 单独或与 LTA 联合是否能调节健康大鼠的葡萄糖、脂质和蛋白质代谢尚不清楚。因此，我们用 EGCG 或 EGCG 与 LTA 的混合物（EGCG+LTA）处理健康大鼠，以研究 EGCG 对营养代谢的影响以及 LTA 在 EGCG 代谢调节作用中的作用。结果表明，与对照组相比，EGCG 激活了胰岛素和 AMP 激活的蛋白激酶（AMPK）信号，从而调节葡萄糖、脂质和蛋白质代谢。与 EGCG 相比，EGCG+LTA 增加了肝和肌肉糖原水平，并抑制了 AMPK、糖原合酶 2、哺乳动物雷帕霉素靶蛋白和核糖体蛋白 S6 激酶的磷酸化。此外，EGCG+LTA 抑制了肝激酶 B1、胰岛素受体和胰岛素受体底物的表达，并促进了乙酰辅酶 A 羧化酶的磷酸化水平。此外，EGCG 和 EGCG+LTA 对幼鼠均无害。总之，EGCG 通过激活 AMPK 和胰岛素途径，促进糖酵解、糖原和蛋白质合成，抑制脂肪酸（FA）和胆固醇合成。然而，LTA 与 EGCG 协同作用，通过 AMPK 信号促进糖原代谢，并抑制 EGCG 对 FA 和蛋白质合成的作用。
