Interrelationships of Sulfate and Glucuronide Conjugation in Indole-fed Rats

Abstract
Effects of protein insufficiency in indole detoxication have been studied in male weanling rats. In a preliminary study rats were fed 8% casein as a basal diet and indole was administered as 0.5% of this diet; in addition, methionine and/or glucose were given as 0.25% of the diet or 1% in the water. Methionine induced increased indican excretion but glucose supplementation did not alter the total excretion of glucuronide. In a subsequent experiment rats fed an 8% casein diet were given indole as 0.25, 0.50 and 0.75% of their diet. Another group received 0.75% indole and 0.25% methionine. The percentage of the indole dose excreted as indican decreased with dosage but indican excretion increased when methionine was supplemented. Total glucuronide in the urine increased when indole was fed. When 2-14C-indole was given by stomach tube it was shown that the ratio of indican to indoxyl glucuronide is 4:1 for the control group but less than one in all groups receiving indole. In the rat glucurono-conjugation is a mechanism independent from sulfoconjugation; glucuronide excretion increases with the body level of indole whereas formation of ester sulfate depends on sulfate availability.