Effects of steroid hormones and xenobiotics on the pubertal development of UDP-glucuronosyltransferase activities towards androsterone and 4-nitrophenol in Wistar rats

Oestradiol benzoate, testosterone propionate, progesterone, corticosterone, 3-methylcholanthrene and phenobarbital were administered to Wistar rats at the pubertal period, and their effects on hepatic UDP-glucuronosyltransferase activities were determined. Pretreatment with oestradiol benzoate had a temporary suppressive effect on androsterone UDP-glucuronosyltransferase activity in rats with the high-activity phenotype of androsterone glucuronidation. The effect was marked in 40-day-old rats, but was not found in older rats. Androsterone UDP-glucuronosyltransferase activity was induced by phenobarbital in rats with the high-activity phenotype, but not in rats with the low-activity phenotype. Foster-feeding experiments showed that breast milk did not alter the genetically determined expression of androsterone UDP-glucuronosyltransferase activity in Wistar rats. In contrast, 4-nitrophenol UDP-glucuronosyltransferase activity was not affected by steroid hormones, but was highly induced by 3-methylcholanthrene.