Green tea extract (GTE) enhances the biliary secretion of dioxin in rats (LB414)

Recently, we have shown that GTE lowers the lymphatic absorption of 2,3,7,8‐tetrachlorodibenzo‐p‐dioxin (TCDD) in rats. The present study was conducted to examine the effect of GTE on the biliary secretion of TCDD in rats. Male rats were fed an AIN‐93G diet with or without (control) GTE at 5 g/kg diet for 2 wk. At 2 wk, rats with bile duct cannulae were infused at 3.0 mL/h for 8 h via a duodenal catheter with a lipid emulsion containing TCDD labeled with 3 H ( 3 H‐TCDD) and 396.0 μmol Na‐taurocholate with or without (control) 76.1 mg GTE in PBS buffer. Bile was collected hourly via bile cannulae for 8 h. No significant difference was noted in bile flow (7.7 ± 0.5 mL in GTE‐infused vs. 7.3 ± 0.5 mL in control rats). However, the biliary secretion of 3 H‐TCDD was significantly enhanced in rats with GTE (7.2 ± 0.4% dose/8 h), compared with those infused with the lipid emulsion alone (6.5 ± 0.2% dose/8 h). Likewise, GTE significantly increased the biliary output of cholesterol and phospholipid. The results indicate that GTE has a stimulatory effect on the biliary excretion of TCDD in rats. The mechanism(s) by which GTE enhances the biliary secretion of dioxin remains to be elucidated.