Possible involvement of group I mGluRs in neuroprotective effect of theanine.
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.
Nagasawa
Kazuki
K
Department of Environmental Biochemistry, Kyoto Pharmaceutical University, 5 Nakauchi-cho, Misasagi, Yamashina-ku, Kyoto 607-8414, Japan. nagasawa@mb.kyoto-phu.ac.jp
Aoki
Hiromitsu
H
Yasuda
Eri
E
Nagai
Katsuhito
K
Shimohama
Shun
S
Fujimoto
Sadaki
S
D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D002540:Cerebral Cortex / Q000166:cytology / Q000187:drug effects / Q000196:embryology / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D005971:Glutamates / Q000494:pharmacology*; D018698:Glutamic Acid / Q000494:pharmacology; D007527:Isoenzymes / Q000378:metabolism; D008734:Methoxyhydroxyphenylglycol / Q000031:analogs & derivatives* / Q000494:pharmacology; D009474:Neurons / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism*; D018696:Neuroprotective Agents / Q000494:pharmacology*; D054799:Phospholipase C beta; D051966:Phospholipase C gamma; D051381:Rats; D018094:Receptors, Metabotropic Glutamate / Q000037:antagonists & inhibitors* / Q000378:metabolism*; D010738:Type C Phospholipases / Q000378:metabolism
D005971:Glutamates; D007527:Isoenzymes; D018696:Neuroprotective Agents; D018094:Receptors, Metabotropic Glutamate; D018698:Glutamic Acid; D008734:Methoxyhydroxyphenylglycol; C026166:theanine; D010738:Type C Phospholipases; D054799:Phospholipase C beta; C518035:Plcb1 protein, rat; D051966:Phospholipase C gamma; C010117:3,4-dihydroxyphenylglycol