| dc.description.abstract | Obesity is considered as a common disease in the world as well as is associated with the risk of diabetes, hypertension, and cardiovascular disease. Obesity results from increases in the fat cell number and/or accumulation of lipid droplets inside of fat cells. Early studies have indicated that IGF-I stimulates the growth of 3T3-L1 preadipocytes; and that catechin-containing green tea reduces body weight of rats, increases energy expenditure and fat acid oxidation of human, and inhibits growth of 3T3-L1 preadipocytes. The exact mechanism of green tea catechin action is still not clear. The present study was to use murine 3T3-L1 preadipocytes to demonstrate at cellular and biochemical levels whether green tea catechins modulate IGF-I stimulation of preadipocyte growth and, if so, to investigate the mechanism of modulation. We found that green tea EGCG was more effective than structurally-related EC, EGC or ECG in reducing the IGF-I-stimulated growth of 3T3-L1 preadipocytes. Further study showed that EGCG reduced activities of CDK-2 and MEK, as indicated by the decreases in the phosphorylation of histone H1 and Erk-1 and Erk-2, respectively. Also, EGCG, but not EC, EGC, or ECG, reduced phosphorylation of IGF-IR, the binding between IGF-IR and IRS-1, and the phosphorylation of IRS-1 and Shc. We conclude that EGCG reduces IGF-I-stimulated growth of 3T3-L1 preadipocytes through inhibiting the pathway of IGF-I signaling transduction. | en_US |