l-Theanine healed NSAID-induced gastric ulcer by modulating pro/antioxidant balance in gastric ulcer margin
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l-Theanine is a unique non-protein-forming amino acid present in tea [Camellia sinensis (L.) O. Kuntze]. In the present work, we evaluated the healing effect of l-theanine on NSAID (indomethacin)-induced gastric ulcer. Histology of the stomach tissues revealed maximum ulceration on the third day after indomethacin administration (18 mg/kg, single dose p.o.) which was accompanied by increased lipid peroxidation; protein carbonylation; Th1 cytokine synthesis, and depletion of thiol, mucin, prostaglandin (PG) E, Th2 cytokine synthesis; and total antioxidant status in mice. l-Theanine healed gastric ulcer at a dose of 10 mg/kg b.w. but aggravated the ulcerated condition at a higher dose of 40 mg/kg b.w. At 10 mg/kg b.w., l-theanine significantly alleviated the adverse oxidative effect of indomethacin through enhanced synthesis of PGE2 by modulation of cyclo-oxygenase-1 and 2 [COX-1 and COX-2] expression, Th1/Th2 cytokine balance, and restoration of cellular antioxidant status at the gastric ulcer margin. The present study revealed for the first time the dose-dependent biphasic effect of a natural neuroprotective agent, l-theanine, on gastric ulcer disease.
KeywordsAntioxidant COX Cytokines Gastric ulcer Indomethacin l-Theanine NSAID
S.C. is grateful to Tea Board, Govt. of India, for providing a research fellowship. The authors would like to thank Mr. Narendra Kumar, SSO (Biochemistry), DTR&DC, Tea Board, Kurseong (GOI) for providing Darjeeling tea samples for l-theanine analysis and for his unconditional help throughout the work. This work was supported by funds from Tea Board, India (GOI).
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