Effect of green tea on blood glucose levels and serum proteomic patterns in diabetic (db/db) mice and on glucose metabolism in healthy humans
Hiroshi Tsuneki, Mitsuyo Ishizuka, Miki Terasawa, Jin-Bin Wu, Toshiyasu Sasaoka, Ikuko Kimura, Hiroshi Tsuneki, Mitsuyo Ishizuka, Miki Terasawa, Jin-Bin Wu, Toshiyasu Sasaoka, Ikuko Kimura
Abstract
Background: Green tea is widely consumed in Asian countries and is becoming increasingly popular in Western countries. Epidemiologically, it has been suggested that green tea consumption prevents type 2 diabetes. The present study was aimed at providing evidence of improvement in glucose metabolism in diabetic mice and healthy humans upon green tea consumption.
Results: Green tea promoted glucose metabolism in healthy human volunteers at 1.5 g/body in oral glucose tolerance tests. Green tea also lowered blood glucose levels in diabetic db+/db+ mice and streptozotocin-diabetic mice 2-6 h after administration at 300 mg/kg without affecting serum insulin level, whereas no effect was observed in control mice (+m/+m and normal ddY mice). The serum protein profiles of db+/db+ and +m/+m mice were analyzed for the first time by SELDI (surface-enhanced laser desorption/ionization)-TOF (time-of-flight)-MS (mass spectrometry), and then compared to investigate any effects of oral green tea administration on serum proteins. The protein profiles in db+/db+ mice showed that the spectral peak intensities at the mass/charge ratios (m/z) of 4119, 4203, 4206, 4211, 4579, 9311 and 18691 were >3 times lower, and those of 13075, 17406, 17407, 17418, 17622, 18431 and 26100 were >3 times higher than respective peak intensities in +m/+m mice. When green tea was administered to db+/db+ mice, the peak intensities were markedly decreased at m/z 11651 and 11863, and slightly decreased at m/z 4212. The peak intensities at 7495, 7595, 7808, 14983, 15614, 31204 were markedly increased after the administration.
Conclusion: The present study provides evidence that green tea has an antidiabetic effect. Although we could not find simple reversed effect of green tea on the diabetes-induced modifications of the levels of several serum proteins, we found that the 4211 (4212) Da protein level that was decreased in the diabetic state was further decreased after green tea administration. This is the first report demonstrating that a certain serum protein may be involved in the antihyperglycemic effect of green tea. The contribution of this protein should be further studied.
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References
- Benelli R, Vene R, Bisacchi D, Garbisa S, Albini A. Anti-invasive effects of green tea polyphenol epigallocatechin-3-galleate (EGCG), a natural inhibitor of metallo and serine proteases. Biol Chem. 2002;383:101–105.
- Weisburger JH, Chung FL. Mechanisms of chronic diseases causation by nutritional factors and tobacco products and their prevention by tea polyphenols. Food Chem Toxicol. 2002;40:1145–1154. doi: 10.1016/S0278-6915(02)00044-3.
- Wu LY, Juan CC, Hwang LS, Hsu YP, Ho PH, Ho LT. Green tea supplementation ameliorates insulin resistance and increases glucose transporter IV content in a fructose-fed rat model. Eur J Nutr. 2004;43:116–124. doi: 10.1007/s00394-004-0450-x.
- Kasahara T, Kato T. A new redox-cofactor vitamin for mammals. Nature. 1993;422:832. doi: 10.1038/422832a.
- Wu L-Y, Juan C-C, Ho L-T, Hsu Y-P, Hwang L-S. Effect of green tea supplementation on insulin sensitivity in Sprague-Dawley rats. J Agric Food Chem. 2004;52:643–648.
- Kobayashi Y, Suzuki M, Satsu H, Arai S, Hara Y, Suzuki K, Miyamaoto Y, Shimizu M. Green tea polyphenols inhibit the sodium-dependent glucose transporter of intestinal epithelial cells by a competitive mechanism. J Agric Food Chem. 2000;48:5618–5623. doi: 10.1021/jf0006832.
- Sabu MC, Smitha K, Kuttan R. Anti-diabetic activity of green tea polyphenols and their role in reducing oxidative stress in experimental diabetes. J Ethnopharmacol. 2002;83:109–116. doi: 10.1016/S0378-8741(02)00217-9.
- Keijzers GB, De Galan BE, Tack CJ, Smits P. Caffeine can decrease insulin sensitivity in humans. Diabetes Care. 2002;25:364–369.
- Nakanishi T, Koyama R, Ikeda T, Shimizu A. Catalogue of soluble proteins in the human vitreous humor: comparison between diabetic retinopathy and macular hole. J Chromatogr B Analyt Technical Biomed Life Sci. 2002;776:89–100. doi: 10.1016/S1570-0232(02)00078-8.
- Kaszkin M, Beck K-F, Eberhardt W, Pfeilschfter J. Unravelling green tea's mechanisms of action: More than meets the eye. Mol Pharmacol. 2004;65:15–17. doi: 10.1124/mol.65.1.15.
- Loew D, Kaszkin M. Approaching the problem of bioequivalence of herbal medicinal products. Phytother Res. 2002;16:705–711. doi: 10.1002/ptr.1248.
- Stanley S, Wynne K, Bloom S. Gastrointestinal satiety signals III. Glucagon-like peptide 1, oxyntomodulin, peptide YY, and pancreatic polypeptide. Am J Physiol Gastrointest Liver Physiol. 2004;286:G693–G697. doi: 10.1152/ajpgi.00536.2003.
- Baetens D, Stefan Y, Ravazzola M, Malaisse-Lagae F, Coleman DL, Orci L. Alteration of islet cell populations in spontaneously diabetic mice. Diabetes. 1978;27:1–7.
- Shiwa M, Nishimura Y, Wakatabe R, Fukawa A, Arikuni H, Ota H, Kato Y, Yamori T. Rapid discovery and identification of a tissue-specific tumor biomarker from 39 human cancer cell lines using the SELDI ProteinChip platform. Biochem Biophys Res Commun. 2003;309:18–25. doi: 10.1016/S0006-291X(03)01520-1.
Source: PubMed