Neonatal modulation of adult rat hepatic microsomal benzo[a]pyrene hydroxylase activities by aroclor 1254 or phenobarbital
✍ Scribed by Haake-McMillan, J. M. ;Safe, S. H.
- Publisher
- John Wiley and Sons
- Year
- 1990
- Tongue
- English
- Weight
- 811 KB
- Volume
- 5
- Category
- Article
- ISSN
- 0887-2082
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✦ Synopsis
The constitutive and Aroclor 1254-induced activities of hepatic microsomal benzo[a]pyrene hydroxylases in male and female rats were determined in animals from ages 11 to 120 days. In 11-day-old noninduced male rats, benzo[a]pyrenediones and 9-hydroxybenzo[a]pyrene were the major microsomal metabolites; in 21-day-old males benzo[a]pyrene-diones and benzo[a]pyrene-9,lOdihydrodiol were predominant, In 60-and 120-dayold animals 3-hydroxybenzo[a]pyrene was the major microsomal metabolite. A similar trend was observed for the development of benzo[a]pyrene hydroxylase activities in female rats. With the exception of 4,5-dihydrodiol formation, the highest induction of individual and total benzo[alpyrene hydroxylase activities by Aroclor 1254 was observed in the 21-day-old immature male rats, in which there was a 330-and 4.5-fold increase in the formation of 3-hydroxybenzo[a]pyrene and quinone metabolites, respectively. The induction of benzo[alpyrene total metabolite formation by Aroclor 1254 in female rats from 11 to 120 days of age was relatively constant (i.e., 13.3-to 10.1-fold induction); however, the relative induction of the individual benzo[a]pyrene hydroxylases was highly variable. In a second set of experiments, male and female rats were neonatally exposed to phenobarbital (600 pmol/kg) or Aroclor 1254 (100 pmollkg), and the effects of these xenobiotics on neonatal imprinting of hepatic microsomal benzotalpyrene hydroxylase activities were determined in the 120-dayold animals. Neonatal exposure to phenobarbital resulted in a decrease in the Aroclor 1254-induced rates of formation of dihydrodiol and quinone benzo[a]pyrene metabolites in male rat microsomes, an increase in the rates formation of the 9,lO-and 7,&dihydrodiols in Aroclor 1254-induced female rat mi-