Histochemical studies on peroxisomes of rat livers during DEHP administration and after withdrawal on thick sections by means of light microscopy and high voltage electron microscopy.

Abstract

Peroxisomal changes of rat livers were examined during DEHP (di-2-ethyl-hexyl phthalate) administration and after withdrawal. Twelve male Wistar rats were fed with the chow containing 2% (w/w) DEHP. Two rats were killed at 1, 3, 5, 7, 14 and 21 days respectively. Eight rats were fed with the same chow for 14 days and two each were killed at 1, 3, 5 and 7 days after DEHP was withdrawn. Two from eight normal control rats were killed at 0, 7, 14 and 21 days respectively. Liver tissues were prefixed in 2.5% glutaraldehyde, processed through DAB reaction, postfixed in 1% osmium tetroxide and were embedded in Epon. The 0.5μm thick sections were observed by light microscopy and high voltage electron microscopy. In experimental livers, increases in number and size of peroxisomes were observed. The induced peroxisomes were larger, less intensely DAB positive and of lower electron dense than those of the controls. After the withdrawal, the number and size of peroxisomes decreased to a normal level in one week. Each peroxisome induced with DEHP might have a low content of catalase and high volume of the enzyme protein employed in fatty acyl-CoA oxidation. There is heterogeneity of peroxisomes from the morphological and histochemical viewpoint.