Dexamethasone increases UDP-glucuronyltransferase activity towards bilirubin, oestradiol and testosterone in foetal liver from rhesus monkey during late gestation.

We previously showed that in perinatal rhesus monkeys hepatic UDP-glucuronyltransferase activities appear to develop differentially in two clusters, analogous to those of the rat. We demonstrate here that hepatic UDP-glucuronyltransferase activities differ between the rat and the rhesus monkey in their response to glucocorticoids. Treatment of pregnant rhesus monkeys with dexamethasone during late gestation increases UDP-glucuronyltransferase activities towards bilirubin, oestradiol and testosterone in the foetal-liver microsomal fraction to 25, 4 and 4 times their low control values respectively. Analogous dexamethasone treatment in rat fails to increase these activities significantly in the foetal liver. These findings suggest that maternal glucocorticoid therapy in late gestation could greatly increase the newborn primate's capacity to glucuronidate bilirubin.