The Hypocholesterolemic Effect of Green Tea EGCG Was Not Mediated Via the Stimulation of the Low-Density Lipoprotein Receptor Gene Expression in Cholesterol-Fed Rats

  • Moon Hee-Jung (Department of Food and Nutritional Sciences, Ewha Womans University) ;
  • Kim Yangha (Department of Food and Nutritional Sciences, Ewha Womans University)
  • Published : 2005.08.01

Abstract

Green tea, which has high polyphenols amount, is thought to have hypocholesterolemic effects. The present study was performed to further examine the hypocholesterolemic action of green tea, especially (-) epigallocatechin gallate (EGCG) for its effect on diet-induced hypercholesterolemia in rats. Male Sprague-Dawley rats (n=15) were fed a green tea-free diet (control), $1.0\%$ green tea catechin (catechin) or $0.5\%$ green tea catechin EGCG for seven weeks. Hypercholesterolemia was induced by adding $1\%$ cholesterol and $0.5\%$ cholic acid to all diets. There was no difference in food intake and body weight gain among the groups. The green tea EGCG treatment led to a significant improvement in plasma levels of total cholesterol, low density lipoprotein (LDL)-cholesterol and high density lipoprotein (HDL)/LDL ratio (p<0.05). There was no significant effect on the plasma HDL-cholesterol level. The catechin treatment led to a 4.19-fold increase in the LDL-receptor mRNA level compared to the control, but the EGCG treatment did not affect the hepatic LDL-receptor mRNA level. Our results suggest that when blood cholesterol level is down-regulated by green tea EGCG, the LDL receptor gene-independent pathway may dominate the hypocholesterolemic action of EGCG.

References

  1. CVD prevention and control: missed opportunities. WHO, 2005
  2. Brown MS, Goldstein JL. A receptor-mediated pathway for cholesterol homeostasis. Science 232:34-47, 1986 https://doi.org/10.1126/science.3513311
  3. Kono S, Shinchi K, Ikeda N, Yanai F, Imanishi K. Green tea and serum lipid profiles: A cross-sectional study in Northern Kyushu, Japan. Prev Med 21:526-531, 1992 https://doi.org/10.1016/0091-7435(92)90060-U
  4. Imai K, Nakachi K. Cross sectional study of effects of drinking green tea on cardiovascular and liver diseases. Br Med J 310:693-696, 1996
  5. Tijburg LBM, Mattern T, Folts JD, Weisberger UM, Katan MB. Tea flavonoids and cardiovascular diseases: A review. Crit Rev Food Sci Nutr 37:771-785, 1997 https://doi.org/10.1080/10408399709527802
  6. Assmann G, Cullen P, Jossa F, Lewis B, Mancini M. Coronary Heart Disease: reducing the risk. Arterioscler Thromb Vase Biol 19:1819-1824, 1999 https://doi.org/10.1161/01.ATV.19.8.1819
  7. Muramatsu K, Fukuyo M, Hara Y. Effect of green tea catechins on plasma cholesterol level in cholesterol fed rats. J Nutr Sci Vitamino 32:613-622, 1986 https://doi.org/10.3177/jnsv.32.613
  8. Matsuda H, Chisaka T, Kubomura Y, Yamahara J, Sawada T, Fujimura H, Kimura H. Effects of crude drugs on experimental hypercholesterolemia. I. Tea and its active principles. J Ethnopharmacol 17:213-224, 1986 https://doi.org/10.1016/0378-8741(86)90110-8
  9. Yang TIC, Koo MW. Hypocholesterolemic effects of Chinese tea. Pharmacol Res 35:505-512, 1997 https://doi.org/10.1006/phrs.1997.0176
  10. Lin YL, Cheng CY, Lin YP, Lau YW, Juan IM, Lin JK. Hypolipidemic effect of green tea leaves through induction of antioxidant and phase II enzymes including superoxide dismutase, catalase, and gluthathione S-transferase in rats. J Agrie Food Chem 46:1893-1899, 1986
  11. Vinson JA, Dabbagh YA. Effect of green and black tea supplementation on lipids, lipid oxidation and fibrinogen in the hamsters-mechanisms for the epidemiological benefits of tea drinking. FEBS Lett 433:44-46, 1998 https://doi.org/10.1016/S0014-5793(98)00880-1
  12. Chan PT, Fong WP, Cheung YL, Huang Y, Ho WKK, Chen ZY. Jasmine green tea epicatechins are hypolipidemic in hamsters (Mesocrieetus auratus) fed a high fat diet. J Nutr 129:1094-1101, 1999
  13. Brown MS, Goldstein JL. Sterol regulatory element binding proteins (SREBPs): controllers of lipid synthesisand cellular uptake. Nutr Rev 56:S1-S3, 1998 https://doi.org/10.1111/j.1753-4887.1998.tb01693.x
  14. Christina Bu, Paul DR, Cynthia DK, Bottema, Sebely pal. Green tea upregulation the low-density lipoprotein receptor through the sterol-regulated element binding protein in HepG2 liver cells. J Agric Food Chem 49:5639-5645, 2001 https://doi.org/10.1021/jf010275d
  15. Choi SH, Lee BH, Choi HD. Analysis of catechin contents in commercial green tea by HPLC. J Korean Soc Food Nutr 21:386-389, 1992
  16. National Institute of Health. Guide for the care and use of laboratory animals, Publication No. 85-123(rev.). 1985
  17. Friedewald WT, Levey RI. Estimation of the concentration of low-density lipoprotein cholesterol in plasma, without use of the preparative ultracentrifuge. Clin Chem 18:499-502, 1972
  18. Chomczynski P, Sacchi N. Single-step method of RNA isolation by acid guanidinium thiocyanate-phenol-chloroform extraction. Anal Biochem 162:156-159, 1987
  19. Steel RGD, Torrie JH. Principles and procedures of statistics. pp.55-60, McGraw-Hill. New York, 1989
  20. Daniel GR, Manfred FS, Volker EL, Peter WE. Effect of EGCG on lipid absorption and plasma lipid levels in rats. J Nutri Biochem 14:326-332, 2003 https://doi.org/10.1016/S0955-2863(03)00054-8
  21. Choi MJ, Jo HJ. Effects of isoflavones supplemented diet on lipid concentrations and hepatic LDL, receptor mRNA level in growing female rats. The Korean Nutr Society 38(5):344-351, 2005
  22. Ando T, Nishimura T, Matsubayashi A, Ejiri H, Inoue K, Nakayama Y, Uchiyama S, Kakuda T, Mukai I. Effects of tea catechins on cholesterol absorption with exogenously hypercholesterolemic rat (ExHC-Ta). Bull Kanagawa Dent Coll 17:21-3, 1989
  23. Yang TTC, Koo MWL. Chinese green tea lowers cholesterol level through an increase in fecal lipid excretion. Life Sci 66:411-23, 2000
  24. Chisaka T, Matsuda H, Kubomura Y, Mochizuki M, Yamahara J, Fujimura H. The effect of crude drugs on experimental hypercholesterolemia: Mode of action of (-)-Epigallocatechin gallate in tea leaves. Chem Pharm Bull 36:227-233, 1988 https://doi.org/10.1248/cpb.36.227
  25. Ikeda I, Imasato Y, Sasaki E, Nakayama M, Nagao H, Takeo T, Yayabe F, Sugano M. Tea catechins decrease micellar solubility and intestinal absorption of cholesterol in rats. Biochim Biophys Acta 1127:141-6, 1992 https://doi.org/10.1016/0005-2760(92)90269-2