摘要：
L‐theanine found in tea leaves helps protect the liver from damage caused by excessive alcohol consumption. It accelerates alcohol metabolism by increasing the expression of related enzymes, reduces the accumulation of harmful substances like reactive oxygen species by inhibiting CYP2E1 and enhancing antioxidant enzyme activity, and alleviates liver inflammation by modulating the TNF‐α/NF‐κB pathway, thus minimizing liver damage. Abstract Scope Acute alcoholic liver injury (AALI), a global health concern, is exacerbated by excessive episodic drinking. L‐theanine (LTA), a compound found in tea leaves, mitigates the AALI‐induced liver oxidative stress and inflammation. However, its relationship with alcohol metabolism and its liver‐protective mechanism remains unexplored. Methods and results This study investigates the protective mechanisms of LTA against AALI in mice. The results demonstrate that LTA mitigates liver tissue damage and reduces the serum levels of aspartate aminotransferase and alanine aminotransferase, and liver levels of triglycerides, malondialdehyde, reactive oxygen species (ROS), tumor necrosis factor‐α, interleukin‐6, and interleukin‐1β. However, LTA enhances the activity of ethanol‐metabolizing enzymes and decreases ethanol and acetaldehyde serum levels. Mechanistically, LTA accelerates alcohol metabolism by upregulating the hepatic expression of ADH6, ALDH1B1, ALDH2, CAT, and ACSS1 mRNA and protein in AALI mice, LTA downregulates the expression of CYP2E1 mRNA and protein and promoting antioxidative activities thus reducing the accumulation of ROS. This attenuated inflammation by inhibiting the phosphorylation of nuclear factor‐kappa B inhibitor alpha (IκBα) and downregulating the hepatic expression of NF‐κB p65, TNF‐α, IL‐1β, IL‐6 mRNA, and protein. Conclusion LTA is a beneficial dietary supplement that protects against AALI by modulating alcohol metabolism and the TNF‐α/NF‐κB pathway.
摘要：
Heat stress can impair the male reproductive function. l-Theanine and dihydromyricetin have biological activities against heat stress; however, their effects on reproductive function in heat-stressed males are unclear. In this study, male mice were given l-theanine, dihydromyricetin, or a combination of both for 28 days, followed by 2 h of heat stress daily for 7 days. All interventions alleviated heat stress-induced testicular damage, improving the testicular organ index, sperm density, acrosome integrity, sperm deformity rate, and hormone levels. Treatment increased the antioxidant enzyme activity and decreased the markers of oxidative and inflammatory stress in the testes. A combination dose of 200 + 200 mg kg(-1) d(-1) showed the best protective effect. The potential mechanism involves the regulation of HSP27 and HSP70, which regulate the levels of reproductive hormones through the StAR/Cyp11a1/Hsd3b1/Cyp17a1/Hsd17b3 pathway, alleviate inflammation and oxidative stress through the P38/NF-kappa B/Nrf2/HO-1 pathway, and regulate the Bcl-2/Fas/Caspase3 apoptotic pathway. Overall, l-theanine and dihydromyricetin may play a protective role against heat stress-induced reproductive dysfunction, suggesting their potential use in heat stress-resistant foods.
摘要：
Alterations to the gut microbiota are associated with ulcerative colitis (UC), whereas restoration of normobiosis can effectively alleviate UC. l-Theanine has been shown to reshape the gut microbiota and regulate gut immunity. To investigate the mechanisms by which l-theanine alleviates UC, we used l-theanine and l-theanine fecal microbiota solution to treat UC mice. In this study, we used l-theanine and l-theanine fecal microbiota solution to treat UC mice to explore the mechanism by which l-theanine alleviates UC. By reducing inflammation in the colon, we demonstrated that l-theanine alleviates symptoms of UC. Meanwhile, l-theanine can improve the abundance of microbiota related to short-chain fatty acid, bile acid, and tryptophan production. Single-cell sequencing results indicated that l-theanine-mediated suppression of UC was associated with immune cell changes, especially regarding macrophages and T and B cells, and validated the immune cell responses to the gut microbiota. Further, flow cytometry results showed that the ability of dendritic cells, macrophages, and monocytes to present microbiota antigens to colonic T cells in an MHC-II-dependent manner was reduced after treating normal mouse fecal donors with l-theanine. These results demonstrate that l-theanine modulates colon adaptive and innate immunity by regulating the gut microbiota in an MHC-II-dependent manner, thereby alleviating UC.
通讯机构：
[Xiao, WJ ; Gong, ZH] H;Hunan Agr Univ, Key Lab Tea Sci, Minist Educ, Changsha 410128, Peoples R China.;Hunan Agr Univ, Natl Res Ctr Engn & Technol Utilizat Bot Funct Ing, Changsha 410128, Peoples R China.;Hunan Agr Univ, Sino Kenyan Joint Lab Tea Sci, Changsha 410128, Peoples R China.
摘要：
Heat stress caused by heatwaves, extreme temperatures, and other weather can damage the intestinal barrier of organisms. L-Theanine (LTA) attenuates heat stress-induced oxidative stress, inflammatory responses, and impaired immune function, but its protective effect on the intestinal barrier of heat-stressed organisms is unclear. In this study, low (100 mg kg(-1) d(-1)), medium (200 mg kg(-1) d(-1)), and high (400 mg kg(-1) d(-1)) dosages of LTA were used in the gavage of C57BL/6J male mice that were experimented on for 50 d. These mice were subjected to heat stress for 2 h d(-1) at 40 ± 1 °C and 60 ± 5% RH in the last 7 d. LTA attenuated the heat stress-induced decreases in body mass and feed intake, and the destruction of intestinal villi and crypt depth; reduced the serum levels of FITC-dextran and D-LA, as well as the DAO activity; and upregulated the colonic tissues of Occludin, Claudin-1, and ZO-1 mRNA and occludin protein expression. The number of goblet cells in the colon tissue of heat-stressed organisms increased in the presence of LTA, and the expression levels of Muc2, Muc4 mRNA, and Muc2 protein were upregulated. LTA increased the abundance of Bifidobacterium and Turicibacter, and decreased the abundance of Enterorhabdus and Desulfovibrio in the intestinal tract of heat-stressed organisms and restored gut microbiota homeostasis. LTA promoted the secretion of IL-4, IL-10, and sIgA and inhibited the secretion of TNF-α and IFN-γ in the colon of heat-stressed organisms. The expressions of Hsf1, Hsp70, Hsph1, TLR4, P38 MAPK, p-P65 NF-κB, MLCK mRNA, and proteins were downregulated by LTA in the colon of heat-stressed organisms. These results suggest that LTA protects the intestinal barrier in heat-stressed organisms by modulating multiple molecular pathways. Therefore, this study provides evidence on how tea-containing LTA treatments could be used to prevent and relieve intestinal problems related to heat stress.
通讯机构：
[Zhihua Gong; Wenjun Xiao] K;Key Laboratory of Tea Science of Ministry of Education, Hunan Agricultural University, Changsha, Hunan 410128, China<&wdkj&>National Research Center of Engineering Technology for Utilization of Botanical Functional Ingredients, Hunan Agricultural University, Changsha, Hunan 410128, China<&wdkj&>Hunan Agricultural University, Co-Innovation Center of Education Ministry for Utilization of Botanical Functional Ingredients, Changsha, Hunan 410128, China<&wdkj&>Key Laboratory for Evaluation and Utilization of Gene Resources of Horticultural Crops, Ministry of Agriculture and Rural Affairs of China, Hunan Agricultural University, Changsha, China
摘要：
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)alpha expression through the inter-leukin (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 PPAR alpha inhibition. Therefore, L-theanine alleviates the adverse effects of high-protein diets via the FABP5/IL-6/STAT3/PPAR alpha pathway and regulates the immunity of normally fed rats through the epoxide hydrolase (EPHX)2/nuclear factor-kappa B inhibitor (I kappa B)alpha/triggering receptor expressed on myeloid cells (TREM)1 axis.
通讯机构：
[Wenjun Xiao; Wenjun Xiao Wenjun Xiao Wenjun Xiao] K;Key Lab of Tea Science of Ministry of Education, Hunan Agricultural University, Changsha, China<&wdkj&>National Research Center of Engineering Technology for Utilization of Botanical Functional Ingredients, Hunan Agricultural University, Changsha, China<&wdkj&>Co-Innovation Center of Education Ministry for Utilization of Botanical Functional Ingredients, Changsha, China
关键词：
bile acid;cholesterol;cholesterol 7alpha monooxygenase;messenger RNA;theanine;animal;C57BL mouse;genetics;intestine flora;lipid metabolism;liver;male;metabolism;mouse;Animals;Bile Acids and Salts;Cholesterol;Cholesterol 7-alpha-Hydroxylase;Gastrointestinal Microbiome;Lipid Metabolism;Liver;Male;Mice;Mice, Inbred C57BL;RNA, Messenger
通讯机构：
[Zhihua Gong; Wenjun Xiao] K;Key Lab of Tea Science of Ministry of Education, Hunan Agricultural University, Changsha, Hunan 410128, China<&wdkj&>National Research Center of Engineering Technology for Utilization of Botanical Functional Ingredients, Hunan Agricultural University, Changsha, Hunan 410128, China<&wdkj&>Co-Innovation Center of Education Ministry for Utilization of Botanical Functional Ingredients, China<&wdkj&>Hunan Agricultural University, Hunan Collaborative Innovation Center for Utilization of Botanical Functional Ingredients, Changsha, Hunan 410128, China
通讯机构：
[Wenjun Xiao] N;National Research Center of Engineering Technology for Utilization of Botanical Functional Ingredients, Hunan Agricultural University, Changsha 410128, China<&wdkj&>Key Lab of Tea Science of Ministry of Education, Hunan Agricultural University, Changsha 410128, China<&wdkj&>Co-Innovation Center of Education Ministry for Utilization of Botanical Functional Ingredients, Hunan Agricultural University, Changsha 410128, China<&wdkj&>Key Laboratory for Evaluation and Utilization of Gene Resources of Horticultural Crops, Ministry of Agriculture and Rural Affairs of China, Changsha 410128, China<&wdkj&>Author to whom correspondence should be addressed.
摘要：
As the irreversible products of the non-enzymatic reduction of sugars and the amino groups of proteins or peptides, advanced glycation end products (AGEs) are metabolized and excreted via the kidneys. However, if AGEs are not metabolized, they are deposited in the kidneys and bind to AGE receptors (RAGE), which can induce various pathological changes, including oxidative stress, apoptosis, and inflammation. This study used the D-galactose (DG)-induced rat model to explore the potential role and mechanism of L-theanine in inhibiting AGEs/RAGE-related signaling pathways in renal tissues. L-theanine increased the activities of glutathione peroxidase (GSH-Px) and total antioxidant capacity (T-AOC) while downregulating the contents of malondialdehyde (MDA) and AGEs in renal tissues induced by DG (P<0.05). By inhibiting the upregulation of RAGE protein expression attributed to AGEs accumulation (P<0.05), L-theanine downregulated phosphorylated nuclear factor (p-NF-κB (p65)), Bax, and cleaved-caspase-3 expression and increased Bcl-2 protein expression (P<0.05), thereby alleviating the oxidative stress damage and reducing the inflammation and cell injury induced by DG. In addition, the Congo red staining section of renal tissue also showed that the natural product L-theanine can protect against AGEs-induced renal damage in DG-induced rat model.
作者机构：
湖南农业大学, 茶学教育部重点实验室, 湖南, 长沙, 410128;国家植物功能成分利用工程技术研究中心, 国家植物功能成分利用工程技术研究中心, 湖南, 长沙, 410128;植物功能成分利用省部共建协同创新中心, 湖南省植物功能成分利用省部共建协同创新中心, 湖南, 长沙, 410128;石门县茶祖印象太平茶业专业合作社, 湖南, 石门, 415300;[崔俪丹; 张湘琳; 项希; 李兰兰; 屈青云; 龚志华; 肖文军] Key Laboratory of Tea Science of Ministry of Education, Hunan Agricultural University, Changsha, 410128, China<&wdkj&>National Research Center of Engineering Technology for Utilization of Functional Ingredients from Botanicals, Hunan Agricultural University, Changsha, 410128, China<&wdkj&>Co-Innovation Center of Education Ministry for Utilization of Botanical Functional Ingredients, Changsha, 410128, China
摘要：
Redox and inflammation imbalances are associated with increased levels of advanced glycation end products (AGEs), leading to the degeneration of body function. L-Theanine, derived from tea, reportedly inhibits AGE formation in vitro. We investigated the effects on AGE content, oxidative stress, and inflammatory factors in D-galactose-induced aging rats for prevention and treatment of age-related liver dysfunction. L-Theanine increased activities of antioxidant enzymes such as superoxide dismutase, catalase, and glutathione peroxidase, thus enhancing total antioxidant capacity, and decreasing malondialdehyde and nitric oxide synthase levels in serum and liver. Levels of the pro-inflammatory factors, interleukin (IL)-1 beta, tumour necrosis factor-alpha, and IL-6 were decreased in serum and liver, whereas those of anti-inflammatory factors, IL-4 and IL-10, were increased in the serum. Further, L-theanine inhibited AGE production and decreased the levels of the liver function markers, alanine aminotransaminase and aspartate aminotransferase. It also significantly increased the mRNA expression levels of FoxO1 and downregulated NF-kappa B(p65) but suppressed the phosphorylation of both FOXO1 and NF-kappa B (p65). Moreover, L-theanine effectively attenuated n-galactose-induced oedema and vacuole formation, thus protecting the liver. Overall, L-theanine reversed the D-galactose-induced imbalance in oxidative stress and inflammatory responses, reduced AGEs content in aging rats, maintained homeostasis in the body, and ameliorated liver aging.
