theanine and 3-4-dihydroxyphenylglycol

We investigated the molecular mechanism underlying the neuroprotective effect of theanine, a green tea component, using primary cultured rat cortical neurons, focusing on group I metabotropic glutamate receptors (mGluRs). Theanine and a group I mGluR agonist, DHPG, inhibited the delayed death of neurons caused by brief exposure to glutamate, and this effect of theanine was abolished by group I mGluR antagonists. Although the administration of glutamate alone decreased the neuronal expression of phospholipase C (PLC)-beta1 and -gamma1, which are linked to group I mGluRs, their expression was equal to the control levels on cotreatment with theanine. Treatment with theanine or DHPG alone for 5-7 days resulted in increased expression of PLC-beta1 and -gamma1, and the action of theanine was completely abolished by group I mGluR antagonists. These findings indicate that group I mGluRs might be involved in neuroprotective effect of theanine by increasing the expression levels of PLC-beta1 and -gamma1.

Topics: Animals; Apoptosis; Cell Survival; Cells, Cultured; Cerebral Cortex; Dose-Response Relationship, Drug; Glutamates; Glutamic Acid; Isoenzymes; Methoxyhydroxyphenylglycol; Neurons; Neuroprotective Agents; Phospholipase C beta; Phospholipase C gamma; Rats; Receptors, Metabotropic Glutamate; Type C Phospholipases