Responses of the D-glucuronic acid pathway in rat tissues to treatment with tetrachlorodibenzodioxin.

1. 2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) was administered to rats to study its effects on the enzyme activities of the D-glucuronic acid pathway in the liver, small intestine and kidney.2. The UDP-glucuronosyl transferase activity of male albino rats given TCDD (80 μg/kg, one dose, i.p.) 6 days before killing was significantly increased in all tissues examined, and UDP-glucuronic acid pyrophosphatase activity was markedly decreased in the liver. D-Glucuronolactone and L-gulonate de-hydrogenase activities in the liver and small intestine were slightly decreased after TCDD treatment.3. The activities of UDP-glucose dehydrogenase and β-glucuronidase were unchanged.4. The 24 h urinary excretion of L-ascorbic acid was enhanced 8-fold, although no difference was detected in the excretion of D-glucaric acid between the control and experimental animals.5. These results suggest an increased capacity for glucuronide conjugation after treatment with TCDD.6. The lack of increase in the urinary excretion of D-glu...