β-glucuronidase activity in adrenal gland, liver, spleen, kidney, and serum of cats and guinea pigs during maturation

Abstract

Cats differ from rats in that they do not excrete steroid glucuronides in the urine and there is evidence that they have diminished capacity for synthesizing them. Guinea pigs, which synthesize them readily, also do not excrete them in the urine. It has been postulated that this absence of glucuronides in urine might result from an increased rate of hydrolysis of glucuronides by β-glucuronidase. Therefore, tissue and serum β-glucuronidase levels have been measured for cats and guinea pigs, comparing their activities with each other and with those of the rat, run as reference standards in each assay. Enzymic activities were measured in adult animals, and as a function of maturation. There exists a marked difference in the activity of β-glucuronidase in the adrenal gland, liver, spleen, and kidney of the two mammals, the cat and the rat, whose capacities for the formation of glucuronides are not the same and in which the biosynthesis and metabolism of steroids are quite different. Activities in the four organs are closer together for the cat and guinea pig than for either of these animals compared to the rat. The activities of β-glucuronidase in the liver, spleen, and kidney of the rat are two to three times higher than in the same organs of the cat; the adrenal gland of the cat exhibits twice the β-glucuronidase activity observed in the rat adrenal. Changes in β-glucuronidase activity with age were determined in the cats and guinea pigs. In the cat, whose capacity for the formation of glucuronides seems to be low, a progressive decline of β-glucuronidase activity was observed from the very young animals to adults; the decline is extraordinarily manifested in the liver and also observed in the adrenal gland and the spleen.