title: L-theanine promotes nitric oxide production in endothelial cells through eNOS phosphorylation.
abstract: Consumption of tea (Camellia sinensis) improves vascular function and is linked to lowering the risk of cardiovascular disease. Endothelial nitric oxide is the key regulator of vascular functions in endothelium. In this study, we establish that l-theanine, a non-protein amino-acid found in tea, promotes nitric oxide (NO) production in endothelial cells. l-theanine potentiated NO production in endothelial cells was evaluated using Griess reaction, NO sensitive electrode and a NO specific fluorescent probe (4-amino-5-methylamino-2',7'-difluororescein diacetate). l-Theanine induced NO production was partially attenuated in presence of l-NAME or l-NIO and completely abolished using eNOS siRNA. eNOS activation was Ca(2+) and Akt independent, as assessed by fluo-4AM and immunoblotting experiments, respectively and was associated with phosphorylation of eNOS Ser 1177. eNOS phosphorylation was inhibited in the presence of ERK1/2 inhibitor, PD-98059 and partially inhibited by PI3K inhibitor, LY-294002 and Wortmanin suggesting PI3K-ERK1/2 dependent pathway. Increased NO production was associated with vasodilation in ex ovo (chorioallantoic membrane) model. These results demonstrated that l-theanine administration in vitro activated ERK/eNOS resulting in enhanced NO production and thereby vasodilation in the artery. The results of our experiments are suggestive of l-theanine mediated vascular health benefits of tea.
authors: Vascular Biology Lab, AU-KBC Research Centre, Anna University, MIT Campus, Chennai, India.
authors: Jamila H
authors: JH
authors: Siamwala
authors: Paul M
authors: PM
authors: Dias
authors: Syamantak
authors: S
authors: Majumder
authors: Manoj K
authors: MK
authors: Joshi
authors: Vilas P
authors: VP
authors: Sinkar
authors: Gautam
authors: G
authors: Banerjee
authors: Suvro
authors: S
authors: Chatterjee
mesh_terms: D017209:Apoptosis / Q000187:drug effects; D002118:Calcium / Q000032:analysis / Q000378:metabolism; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D002867:Chromones / Q000494:pharmacology; D042783:Endothelial Cells / Q000187:drug effects* / Q000378:metabolism; D004730:Endothelium, Vascular / Q000166:cytology / Q000187:drug effects; D005419:Flavonoids / Q000494:pharmacology; D005971:Glutamates / Q000494:pharmacology*; D006801:Humans; D019950:Mitogen-Activated Protein Kinase 1 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D009025:Morpholines / Q000494:pharmacology; D019331:NG-Nitroarginine Methyl Ester / Q000378:metabolism; D009569:Nitric Oxide / Q000096:biosynthesis*; D052250:Nitric Oxide Synthase Type III / Q000235:genetics* / Q000378:metabolism; D009952:Ornithine / Q000031:analogs & derivatives / Q000378:metabolism; D019869:Phosphatidylinositol 3-Kinases / Q000235:genetics / Q000378:metabolism; D010766:Phosphorylation; D010936:Plant Extracts / Q000494:pharmacology*; D051057:Proto-Oncogene Proteins c-akt / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D013662:Tea / Q000737:chemistry; D014664:Vasodilation / Q000187:drug effects
chemical_list: D002867:Chromones; D005419:Flavonoids; D005971:Glutamates; D009025:Morpholines; D010936:Plant Extracts; D013662:Tea; D009569:Nitric Oxide; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one; C065027:N(G)-iminoethylornithine; C026166:theanine; D009952:Ornithine; C496314:NOS3 protein, human; D052250:Nitric Oxide Synthase Type III; D019869:Phosphatidylinositol 3-Kinases; D051057:Proto-Oncogene Proteins c-akt; C535150:MAPK1 protein, human; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one; D002118:Calcium; D019331:NG-Nitroarginine Methyl Ester