[CAS NO. 3081-61-6]  L-Theanine

L-theanine can enhance innate immune function by regulating the secretion of immune cytokines. Its administration increases the splenic organ index and decreases the contents of ILs-4/6/10 and the ratio of IL-4/IFN-γ in the serum. High-dose L-theanine administration increases the levels of dopamine and 5-hydroxytryptamine in the pituitary and hippocampus, resulting in decrease in corticosterone level in the serum. L-theanine administration decreases the mRNA expressions of PLC isomers in the liver and PLC-γ1 and PLC-δ1 in the spleen. mRNA expressions of PLC-βf1 in the spleen and PLC isomers mRNA in the heart are up-regulated by L-theanine administration. After being absorbed into the body, L-theanine can penetrate the blood-brain barrier and regulate the secretion of neurotransmitters of central nervous system cells and levels of hormones such as corticosterone (CORT) and adrenaline (EPI) in the serum. L-theanine can increase levels of 5-hydroxytryptamine (5-HT) and noradrenaline, and decrease levels of adrenocorticotropic hormone and CORT in the hippocampus and prefrontal cortex of rats. L-theanine has been implicated in reduction of blood pressure in hypertensive rats. L-theanine could inhibit the glucose uptake by downregulating the related gene expression in the small intestine of rats. Intestinal gene expression of transporters responding to amino acids absorption was stimulated by L-theanine administration.