1. L-theanine promotes nitric oxide production in endothelial cells through eNOS phosphorylation.
- Author
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Siamwala JH, Dias PM, Majumder S, Joshi MK, Sinkar VP, Banerjee G, and Chatterjee S
- Subjects
- Apoptosis drug effects, Calcium analysis, Calcium metabolism, Cell Line, Cell Survival drug effects, Chromones pharmacology, Endothelial Cells metabolism, Endothelium, Vascular cytology, Endothelium, Vascular drug effects, Flavonoids pharmacology, Humans, Mitogen-Activated Protein Kinase 1 antagonists & inhibitors, Mitogen-Activated Protein Kinase 1 genetics, Mitogen-Activated Protein Kinase 1 metabolism, Mitogen-Activated Protein Kinase 3 antagonists & inhibitors, Mitogen-Activated Protein Kinase 3 genetics, Mitogen-Activated Protein Kinase 3 metabolism, Morpholines pharmacology, NG-Nitroarginine Methyl Ester metabolism, Nitric Oxide Synthase Type III metabolism, Ornithine analogs & derivatives, Ornithine metabolism, Phosphatidylinositol 3-Kinases genetics, Phosphatidylinositol 3-Kinases metabolism, Phosphorylation, Proto-Oncogene Proteins c-akt genetics, Proto-Oncogene Proteins c-akt metabolism, Signal Transduction, Tea chemistry, Vasodilation drug effects, Endothelial Cells drug effects, Glutamates pharmacology, Nitric Oxide biosynthesis, Nitric Oxide Synthase Type III genetics, Plant Extracts pharmacology
- 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., (Copyright © 2013 Elsevier Inc. All rights reserved.)
- Published
- 2013
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