Effect of Polychlorinated Biphenyls on Tissue Distribution and Intestinal Absorption of α-Tocopherol in Rats

Abstract

We conducted experiments to elucidate the mechanism by which α-tocopheryl (α-toc) concentration in the liver remarkably in-creases in rats treated with polychlorinated biphenyls (PCB) when excess amounts of DL-α-tocopheryl-acetate (α-toc-ac) were given. First, diets containing 5 and 50mg of α-toc-ac per 100g were respectively added with 0.05% of PCB and given to rats for 10 days, and α-toc distributions in tissues were determined. Next, the disappearance of α-toc from a ligated intestine of vitamin E (E)-deficient rats was then studied. There were no significant differences between the control and the PCB groups in α-toc concentrations in the liver and other tissues except a few tissues when a lower level of a toc-ac (5mg) was given. Conversely, when a higher level of α-toc-ac (50mg) was given, α-toc concentration in the liver of the PCB group significantly increased compared to that of the control group. This agrees with the result previously reported, showing a remarkable repro-ducibility. In addition, α-toc concentrations in tissues other than the liver were also significantly higher in the PCB group than in the control group. Transmigration of α-toc to the liver from other tissues was therefore excluded. The α-toc absorption test using the ligated intestine of Edeficient rats revealed that α-toc disappears from the intestine at a higher rate in the presence of PCB compared to the untreated control group. This may indicate that α-toc absorption by passive diffusion is accelerated in the coexistence of PCB.