DIFFERENTIAL STIMULATION OF HEPATIC MONO-OXYGENASE AND GLUCURONIDATING SYSTEMS IN CHICK-EMBRYO AND NEONATAL RAT BY GLUCOCORTICOIDS

  • 1 January 1979
    • journal article
    • research article
    • Vol. 57  (5) , 256-261
Abstract
White Leghorn embryos infused with corticosterone precociously reproduced the hatching surges of hepatic UDPglucuronosyltransferase activity to 2-aminophenol, aminopyrine N-demethylase activity and cytochrome P-450 concentration. Onset of transferase activity followed that of the others by 48 h over hatching and on infusion. Competence of demethylase and transferase to response to corticosterone appeared over days 12-14. Glucocorticoids are suggested as the natural triggers of both transferase and monooxygenase activities in chick and both processes may share a further control. Exposure of CD rat fetuses at 18 1/2 days to dexamethasone by maternal injection evoked precicious onset of transferase activity to 2-aminophenol but not to bilirubin, nor of demethylase activity or cytochrome P-450 content. Injection of 1 h old or infant rats with dexamethasone did reproduce preciciously onset of the 3 latter and stimulated the former. Competence for glucocorticoid response thus appeared before birth for transferase activity to 2-aminophenol and at birth for the others. Onset of transferase following hatching or glucocorticoid lagged behind that of demethylase or cytochrome P-450 by 48 h in chick embryo and 36 h in newborn and infant rats; only in fetal rat was response of transferase rapid to administered glucocorticoid.

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