[Effect of protoporphyrin on digestive tract absorption of dioxins in rats]

This paper presents the fecal excretion of polychlorinated dibenzo-p-dioxin (PCDD) congeners, and polychlorinated dibenzofuran (PCDF) congeners in male rats fed a diet containing 0.5% disodiumprotoporphyrin (PPNa) or 0.5% hemin. The animals were administered 4 g of 0.5% PPNa or 0.5% hemin diet containing 0.5 ml of the causal rice-bran oil of Yusho that had occurred in the Southwest part of Japan in 1968 and kept on the same diet for five days. The fecal excretion of 2,3,7,8-T4CDD and 2,3,4,7,8-P5CDF in the group fed with 0.5% PPNa were 2.1 and 1.9 times higher, respectively, than that in the group fed with a control diet. Hemin did not show any significant effect on the inhibition of absorption of dioxins. Next, the rats were given a diet containing 0.5% PPNa or 0.5% Hemin for four weeks after a week interval from the day of the causal rice-bran oil administration. The fecal excretion of 2,3,7,8-T4CDD and 2,3,4,7,8-P5CDF in the group fed with 0.5% PPNa were stimulated 2.1 times higher, respectively, than that in the group fed with a control diet. Hemin did not show any significant effect on the inhibition of re-absorption of dioxins.