Theanine alleviates heat stress-induced impairment of immune function by regulating the p38 MAPK signalling pathway in mice

• Published in: Food & function Vol. 14; no. 1; pp. 335 - 343
• Main Authors: Hu, Yuan, Lin, Ling, Liu, Kehong, Liu, Enshuo, Han, Shumin, Gong, Zhihua, Xiao, Wenjun
• Format: Journal Article
• Published: 03.01.2023
• ISSN: 2042-6496; 2042-650X
• DOI: 10.1039/d2fo02775e

With the current trend of global warming, heat stress-induced impairment could seriously endanger human health. l -Theanine is a non-protein amino acid in tea with various biological activities, including immunoregulatory, anti-anxiety, and anti-oxidation. However, its effect on immune function under heat stress and the underlying mechanism are currently unclear. In this study, male BALB/c mice were used as experimental objects to explore the effect of l -theanine on heat stress-induced changes in immune function and its mechanism. Three doses of l -theanine were used: low (100 mg kg −1 d −1 ), medium (200 mg kg −1 d −1 ), and high (400 mg kg −1 d −1 ). Treatment with l -theanine could attenuate the heat stress-induced reductions in body weight and feed intake in mice, alleviate damage in the liver and jejunum, and inhibit the inflammatory factors IL-6, IL-1β, and TNF-α. Aspartate aminotransferase and alanine transaminase activity levels and the malondialdehyde content decreased, while the IgA, IgM, and IgG contents increased in response to l -theanine. It is possible that l -theanine affects the P38 signalling pathway and inhibits the increase in p-P65/P65 caused by the overexpression of HSP27 and regulation of PPAR-γ and Foxp3 proteins, thereby alleviating immune dysfunction caused by heat stress. L-Theanine can regulate the immune system's function and inflammatory responses under heat stress via activation of the p38 MAPK signalling pathway.