title: Neonatal modulation of adult rat hepatic microsomal benzo[a]pyrene hydroxylase activities by Aroclor 1254 or phenobarbital.
abstract: 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-9,10-dihydrodiol were predominant. In 60- and 120-day-old 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[a]pyrene 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[a]pyrene 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 mumol/kg) or Aroclor 1254 (100 mumol/kg), and the effects of these xenobiotics on neonatal imprinting of hepatic microsomal benzo[a]pyrene hydroxylase activities were determined in the 120-day-old animals.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Department of Veterinary Physiology and Pharmacology, Texas A & M University, College Station 77843.
authors.forename: J M
authors.initials: JM
authors.lastname: Haake-McMillan
authors.forename: S H
authors.initials: SH
authors.lastname: Safe
mesh_terms: D000375:Aging / Q000378:metabolism; D000818:Animals; D000831:Animals, Newborn / Q000378:metabolism*; D001140:Aroclors / Q000494:pharmacology*; D001579:Benzopyrene Hydroxylase / Q000187:drug effects*; D020111:Chlorodiphenyl (54% Chlorine); D002851:Chromatography, High Pressure Liquid; D005260:Female; D008297:Male; D008862:Microsomes, Liver / Q000187:drug effects* / Q000201:enzymology; D010634:Phenobarbital / Q000494:pharmacology*; D051381:Rats
chemical_list: D001140:Aroclors; D020111:Chlorodiphenyl (54% Chlorine); D001579:Benzopyrene Hydroxylase; D010634:Phenobarbital