EFFECTS OF SELENIUM DEFICIENCY ON XENOBIOTIC-METABOLIZING AND OTHER ENZYMES IN RAT-LIVER

The present study was undertaken to characterize effects of selenium ( Se) deficiency on 16 enzymes recovered in either one or more of the su bcellular fractions of rat liver (as a basis for future studies on the mechanisms underlying the observed changes). Male rats were fed a Tor ula-yeast based diet with 0.23 mg Se/kg or the same diet with 0.009 mg Se/kg, from weaning and for 10 weeks. Statistically significant effec ts of Se deficiency were the following: Se-dependent glutathione perox idase decreased to 0.14% of these-adequate controls, while cytosolic g lutathione transferase increased 3-fold in Se deficiency when CDNB was the substrate, but decreased significantly when trans-stilbene oxide (diagnostic for subunit 4) was used as the substrate. Cytosolic DT-dia phorase increased about 7-fold in Se deficiency. Further, DT-diaphoras e in the microsomal fraction was also significantly increased in Se de ficiency, as were the microsomal and mitochondrial epoxide hydrolases and microsomal glutathione transferase. Furthermore, increased activit y of the peroxisomal marker enzyme catalase (P < 0.05) was noted in Se -deficient rats. It is our working hypothesis that changes in enzyme a ctivities in Se deficiency are mainly due to changed levels of endogen ously generated metabolites or altered functions of endocrine tissues.