Effects And Mechanism Of L-theanine On Heat Stress

Heat stress is an nonspecific defense response in organism to high temperature stress.When it exceeds the range of self-regulation,A series of heat stress hazards such as physiological dysfunction,decreased growth and production performance,tissue damage and even death occurs,so it has important scientific and practical significance to prevent or alleviate the danger of heat stress safely.Plant functional components,which have multiple targets and multiple pathways in heat stress,are important development directions for developing anti stress health products.As the characteristic of amino acids in tea,L-theanine has antioxidant,regulating immunity,lowering blood pressure,soothe the nerves,and produce excessive antagonism of glutamate excitotoxicity and other cell biological activity,known as the "natural sedative",But have not yet seen the reports on L-theanine with heat stress.The experimental animals of SPF grade Balb/KM male mice were given heat treatment in the simulated temperature and humidity climate box after they were orally pre-treated with different dosages of L-theanine,and through the analysis of related physiological and biochemical indexes and tissue histopathological features,the influence of genes mRNA and protein expression in liver tissue related HSP70 and JNK pathways,preliminary proved effects and mechanism of L-theanine on heat stresse.Results showed:1.L-theanine can promote the feed intake and weight of heat-stress mice,decrease the liver and spleen organ index,reduce the enzyme activity of ALT,AST in serum,and reduce the content of inflammatory mediators,TNF-?,IL-6,IFN –? in serum.decreased content of MDA in liver,improve the enzyme activity of SOD,GSH-PX and CAT,reduces the damage of the jejunum and the liver tissue with heat treatment,among which the L-theanine middle dose had the best effects.2.L-theanine can reduce the mRNA expression of HSP70 in liver tissue of heat-stress mice,can reduce the mRNA expression of JNK activator PI3K?TAK1?MLK3 and MKK4,inhibit the activation of JNK pathway and the mRNA expression of its downstream c-Jun and p53,and inhibit the expression of P38 and ERK pathway in different degrees,among which the L-theanine middle dose had the best effects.3.L-theanine can reduce the protein expression of HSP70 in liver tissue of heat-stress mice,reduce the protein expression of JNK activator PI3K?TAK1?MLK3 and MKK4,inhibit the activation of JNK pathway and the protein expression of its downstream c-Jun and p53,and decrease the phosphorylation level of JNK and P38 pathway.In conclusion,L-theanine can enhance the absorption of nutrients,reduce the expression of inflammatory cytokines,reduce oxidative damage and protect the liver and jejunum tissue.The mechanism is: to prevent heat stress induced cell and tissue damage by inhibiting mRNA and protein overexpression of JNK upstream activator PI3K?TAK1?MLK3 and MKK4,and inhibiting the activation of JNK and the protein expression of its downstream c-Jun and p53,and inhibiting the activation of P38.