Vol. 31, Issue 1, 140-144, January 2003

Bisphenol A Glucuronidation and Absorption in Rat Intestine

Hiroki Inoue,¹ Go Yuki,¹ Hiroshi Yokota,² and Seiyu Kato¹

Department of Veterinary Physiology, School of Veterinary Medicine, Rakuno Gakuen University, Ebetsu, Hokkaido, Japan

Bisphenol A, an environmental estrogen, can be leached from plastic tableware and from the coating of food and drink cans, orally exposing human beings to the compound. The present study focuses on the absorption and metabolism of bisphenol A in the rat intestine, as elucidated experimentally by segmented everted intestine. One hour after the application of 2 µmol of bisphenol A to the mucosal fluid, the absorption of bisphenol A was slightly greater in the colon (48.6%) than in the proximal jejunum (37.5%). In the serosal side, unconjugated bisphenol A appeared in small amounts, increasing distally (maximal 1.6 nmol, colon). Large amounts of the bisphenol A glucuronide were then transported into the serosal side, also increasing distally (proximal, 80.4 nmol; distal, 478.4 nmol). The greatest amount of the glucuronide (~573 nmol) was excreted into the mucosal side of the small intestine, whereas in the colon, mucosal excretion was minimal (67.2 nmol). On high-dose application of bisphenol A to the mucosal fluid, the transported unconjugated bisphenol A increased markedly throughout the intestine and colon. These results suggest that bisphenol A in the intestinal lumen is glucuronidated almost exclusively during its passage through the intestinal wall.