The protein levels in a diet are correlated with immunity but the long-term intake of excessive protein can compromise various aspects of health. L-theanine regulates immunity and protein metabolism; however, how its regulatory immunity effects under a high-protein diet are unclear. We used proteomics, metabonomics, and western blotting to analyze the effects of diets with different protein levels on immune function in rats to determine the role of L-theanine in immunity under a high-protein diet. The long-term intake of high-protein diets (≥40% protein) promoted oxidative imbalance and inflammation. These were alleviated by L-theanine. High-protein diets inhibited peroxisome proliferator-activated receptor (PPAR)α expression through the interleukin (IL)-6/signal transducer and activator of transcription (STAT)3 pathway and mediated inflammation. L-theanine downregulated anti-fatty acid-binding protein 5 (FABP5), inhibited the IL-6/STAT3 axis, and reduced high-protein diet-induced PPARα inhibition. Therefore, L-theanine alleviates the adverse effects of high-protein diets via the FABP5/IL-6/STAT3/PPARα pathway and regulates the immunity of normally fed rats through the epoxide hydrolase (EPHX)2/nuclear factor-kappa B inhibitor (IκB)α/triggering receptor expressed on myeloid cells (TREM)1 axis.

Excessive protein intake causes liver and brain damage and neurotransmitter disorders, thereby inducing cognitive dysfunction. L-theanine can regulate the neurotransmitter content and show great potential in liver and brain protection. However, it remains unclear whether l-theanine effectively regulates neurotransmitter content under high-protein diet. A 40-day feeding experiment was performed in Sprague Dawley rats to investigate the regulatory effects and mechanisms of l-theanine on neurotransmitters via liver-brain axis in high-protein diets. The results showed that a 30% protein diet increased the liver and brain neurotransmitter content while maintaining the normal structure of liver and the hippocampal CA1 of brain and improving the autonomous behavior of rats. In contrast, 40% and 50% protein diets decreased the content of neurotransmitters, affected autonomous behavior, destroyed the hippocampal CA1 of brain structure, increased hepatic inflammatory infiltration, lipid degeneration, and hepatocyte eosinophilic change in liver, increased liver AST, ALT, MDA, CRP, and blood ammonia level, and decreased liver SOD and CAT level. However, l-theanine improved liver and brain neurotransmitter content, autonomous behavior, liver and hippocampal brain structure, and liver biochemical indicators in 40% and 50% protein diets. To explore how LTA can eliminate the adverse effects of a high-protein diet, we analyzed different metabolites and proteomes and using western blotting for validate quantitatively. We found that l-theanine regulates the activity of PF4 and G protein subunit alpha i2, increases the content of brain-derived neurotrophic factor and dopamine under a 20% protein diet. In addition, l-theanine can activate the adenylate cyclase-protein kinase A pathway through the protein alpha/beta-hydrolase domain protein 12 to regulate the content of neurotransmitters under a 40% protein diet, thereby exerting a neuroprotective effect.

SCOPE:l-Theanine (LTA) is a non-protein amino acid that contributes to the flavor of tea and can regulate protein metabolism of healthy organisms. However, it is unknown whether it regulates protein metabolism in individuals on high-protein diets (HPDs).METHODS AND RESULTS:Here, Sprague-Dawley rats are fed HPDs with different protein supply ratios and administered a diverse dose of LTA for 40 days. Results show that HPDs with an energy supply ratio from protein >40% impair the liver and kidneys, elevate serum ammonia and urea nitrogen, induce amino acid (AA) catabolism, and promote fatty acid (FA) synthesis via FA-binding protein 5 (Fabp5) and acetyl-CoA carboxylase 1 (ACC1). LTA intervention alleviates HPD-induced hepatic and renal injury and improves serum biochemical indices. It increases hepatic free AA content and inhibits FA synthesis by downregulating Fabp5 and ACC1. It promotes protein synthesis by acting on the mammalian target of rapamycin (mTOR) pathway, thereby alleviating HPD-induced metabolic disorders.CONCLUSIONS:This study demonstrates that LTA mitigates kidney and liver damage induced by long-term excess HPDs by regulating protein metabolism.

高蛋白饮食可导致焦虑或抑郁自主行为,自主行为是判断是否具有焦虑或抑郁病症的重要方法.本研究通过对SPF级6周龄SD雄性大鼠进行40 d灌胃实验,采用旷场与明暗箱实验观察以及测定生理生化指标的方法,探究不同剂量L-茶氨酸(100、200、400 mg/(kg mb·d))对不同蛋白水平饮食(蛋白质供能比分别为20％、30％、40％、50％) SD大鼠行为变化的干预作用,以期为高蛋白饮食的多元化营养干预及L-茶氨酸深层次利用提供科学依据.结果 表明:与蛋白质供能比为20％的普通维持饲料组相比,蛋白质供能比为50％的高水平高蛋白饲料组的采食量、体质量显著减少(P＜0.05),大鼠在明箱中的停留时间显著缩短(P＜0.05),进入明箱的次数显著减少(P＜0.05),多巴胺、5-羟色胺、去甲肾上腺素质量浓度减少,但无显著差异,说明高水平高蛋白饮食可诱导大鼠抑郁行为.与高水平高蛋白饲料组相比,低剂量L-茶氨酸干预的高水平高蛋白饲料组大鼠体质量显著升高(P＜0.05),且在明箱的停留时间显著延长(P＜0.05);低、中剂量L-茶氨酸干预的高水平高蛋白饲料组大鼠在旷场箱的水平移动格数、后肢站立次数显著增加(P＜0.05);各剂量L-茶氨酸干预的高水平高蛋白饲料组大鼠进入明箱的次数显著增加(P＜0.05),且血清中多巴胺、去甲肾上腺素质量浓度显著升高(P＜0.05);同时低剂量L-茶氨酸干预的高水平高蛋白饲料组大鼠血清中5-羟色胺质量浓度显著升高(P＜0.05).综上,L-茶氨酸具有改善高蛋白饮食所致焦虑或抑郁SD大鼠自主行为的作用,其机制可能与单胺类递质的代谢相关.

提高茶学硕士研究生人才培养质量既是茶产业高质量发展的客观需求,也是贯彻落实国家创新创业型精英教育的根本要求.本文根据新形势下茶产业对创新型高级专业技术人才知识和能力的客观需求,分析了当前我国茶学硕士研究生在招生、人才培养方案、课程教学、创新研究以及导师指导等方面存在的问题,探讨了提高生源质量、优化人才培养方案、创新教学内容与方法、完善研究创新条件、强化导师职能、健全保障制度等对策建议,以期为提高我国茶学研究生教育教学改革和人才培养质量提供参考.

Processing of dark tea varieties, such as Fu brick tea, Liupao tea, Qianliang tea, and Qing brick tea, includes solid-state fermentation involving microorganisms. In this study, we analyzed the major chemical constituents of dark tea extracts and evaluated their modulatory effect on the gastrointestinal function in normal mice, including the improvement of gastrointestinal transit and intestinal microbial, as well as the attenuation of intestinal microbial dysbiosis and intestinal pathological damage, and the adjustment of immune function in antibiotic-treated mice. Substantial differences in major chemical constituents, including total polyphenols, total organic acids, water extract content, 18 free amino acids, gallic acid, and six tea catechins, were observed among Fu brick tea, Qianliang tea, Qing brick tea, and Liupao tea extracts. Extracts from the four dark tea varieties significantly promoted gastrointestinal transit and colonization of beneficial Bifidobacterium and Lactobacillus, and inhibited the growth of harmful Escherichia coli and Enterococcus in normal mice. In addition, Qianliang tea, Qing brick tea, and Liupao tea extracts significantly accelerated the reversal of the ampicillin sodium-induced pathological damage in the ileum, intestinal bacterial dysbiosis (Bifidobacterium, Lactobacillus, E. coli, and Enterococcus), and low immunity.

以茶树品种碧香早、尖波黄和桃源大叶的夏季一芽一叶茶鲜叶为原料,将其分别加工成黄茶,通过感官品质、滋味品质和香气品质分析,探讨3个茶树品种的黄茶适制性.结果表明,与桃源大叶和碧香早相比,尖波黄茶鲜叶更适合于加工黄茶,由其加工而成的黄茶外形色泽金黄、香气清香带甜、滋味醇和较爽、汤色及叶底金黄较亮;水浸出物、氨基酸、茶多酚、黄酮、可溶性糖、茶黄素含量相对较高,分别为43.80％,2.27％,23.09％,1.06％,4.13％,0.24％,且酚氨比值最小,为10.17;儿茶素总量为14.21％,简单儿茶素总量为5.49％,酯型儿茶素含量为8.72％,酯型儿茶素/总儿茶素比值为0.61;同时香气物质种类最多、品质最好,其中大马士酮、十七烷、ɑ-松油醇、邻苯二甲酸二丁酯、4-[2,2,6-三甲基-7-氧杂二环[4.1.0]庚-1-基]-3-丁烯-2-酮、β-蒎烷、葑烯、3,6-壬二烯-1-醇乙酸酯、3,7,11-三甲基-1,3,6,10-十二碳-四烯、1-甲基-4-(2-甲基环氧乙烷基)-7-氧杂双环[4.1.0]庚烷10种香气物质为尖波黄特征性香气成分.研究结果表明,茶树品种尖波黄为加工黄茶的优异品种资源.