Modulation of Endocrine Systems and Food Intake by Green Tea Epigallocatechin Gallate

Abstract

Green tea polyphenols, especially the catechin, (-)-epigallocatechin gallate (EGCG), have been proposed as a cancer chemopreventative based on a variety of laboratory studies. For clear assessment of the possible physiological effects of green tea consumption, we injected pure green tea catechins ip into rats and studied their acute effects on endocrine systems. We found that EGCG, but not related catechins, significantly reduced food intake; body weight; blood levels of testosterone, estradiol, leptin, insulin, insulin-like growth factor I, LH, glucose, cholesterol, and triglyceride; as well as growth of the prostate, uterus, and ovary. Similar effects were observed in lean and obese male Zucker rats, suggesting that the effect of EGCG was independent of an intact leptin receptor. EGCG may interact specifically with a component of a leptin-independent appetite control pathway. Endocrine changes induced by parenteral administration of EGCG may relate to the observed growth inhibition and regression of human prostate and breast tumors in athymic mice treated with EGCG as well as play a role in the mechanism by which EGCG inhibits cancer initiation and promotion in various animal models of cancer.

Green tea catechins for treatment of external genital warts

“…In addition to possessing antiviral [6][7][8] and immunostimulatory [9][10][11][12] properties, catechins also exhibit antitumor [13][14][15][16] and antioxidative 11,17 effects. There is also sufficient evidence for antiangiogenic activity.…”

Suppression of fatty acid synthase in MCF-7 breast cancer cells by tea and tea polyphenols: a possible mechanism for their hypolipidemic effects

“…Similar studies by Yang and Koo 12 have shown that Chinese jasmine green tea has significant serum-and liver-cholesterol lowering effects. Kao et al 13 reported that injection of the tea polyphenol EGCG into mice reduced their food intake and body weight, but the mechanism remains to be elucidated. Recently, an in vitro study has shown that EGCG is an effective inhibitor of FAS isolated from chicken liver.…”

“…Recently, an in vitro study has shown that EGCG is an effective inhibitor of FAS isolated from chicken liver. 13 It seems that because most previous studies on the FAS inhibitors have been confined to their inhibitory effects on the enzyme activity of FAS, 5,7,8,14 it would be more interesting to investigate the inhibitory effects of these compounds on the enzyme biosynthesis of FAS. Our previous studies 10 showed that long-term feeding of Chinese Longjing green tea leaves to rats could reduce their body weight and lipid contents without reducing food intake.…”

Epigallocatechin gallate, a constituent of green tea, suppresses cytokine-induced pancreatic β-cell damage

“…In addition, EGCG was also reported to function as antidiabetic. Injection of EGCG into lean and obese Zucker rats significantly lowered blood glucose and insulin levels, and green tea extract increased glucose metabolism in adipocytes (Broadhurst et al, 2000;Kao et al, 2000). Epicatechin, structurally similar to EGCG, is the active compound in the extract from Pterocarpus marsupium Roxb bark traditionally used in Indian folk medicine to treat diabetes (Ahmad et al, 1989).…”