Modulation of endocrine systems and food intake by green tea epigallocatechin gallate

Green tea polyphenols, especially the catechin, (-)-epigallocatechin gallat e (EGCG), have been proposed as a cancer chemopreventative based on a varie ty of laboratory studies. For clear assessment of the possible physiologica l effects of green tea consumption, we injected pure green tea catechins ip into rats and studied their acute effects on endocrine systems. We found t hat EGCG, but not related catechins, significantly reduced food intake; bod y 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 w ith a component of a leptin-independent appetite control pathway. Endocrine changes induced by parenteral administration of EGCG may relate to the obs erved 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 b y which EGCG inhibits cancer initiation and promotion in various animal mod els of cancer.