title: Cytochrome P-450 isoenzyme content and monooxygenase activities in rat liver: effect of ontogenesis and pretreatment by phenobarbital and 3-methylcholanthrene.
abstract: The overall cytochrome P-450 content and the immunochemically determined concentrations of constitutive isoenzymes UT-A and UT-I and isoenzymes induced by phenobarbital (PB-B), pregnenolone 16 alpha-carbonitrile (PCN-E), beta-naphthoflavone (BNF-B) and isosafrole (ISF-G) were investigated in liver microsomes from developing rats and tentatively correlated with mono-oxygenase activities. In fetuses of untreated rat, although the cytochrome P-450 was easily quantified spectrally, none of the isoenzymes tested could be immunochemically detected. After birth, each isoenzyme develops in untreated animals with its own pattern of evolution. Mono-oxygenase activities exhibited different developmental pictures. Benzphetamine-N-demethylase and lauric acid 11-hydroxylase activities progressively increased up to adult values, aniline hydroxylase activity was maximal in 15-day-old animals and benzopyrene hydroxylase and lauric acid 12-hydroxylation were increased after birth until 15 days of age in both males and females and underwent a second increase in males. Pretreatment with phenobarbital resulted in the precocious onset of PB-B in fetal and neonatal rat liver accompanied by an increase in classically associated monooxygenase activities. The PCN-E concentration was enhanced by phenobarbital pretreatment only at 15 days and in older animals. BNF-B and benzo(a)pyrene hydroxylase activity were significantly increased by 3-methylcholanthrene whatever the age considered, whereas this inductive effect upon ISF-G concentration became effective only after 2 weeks of age. After sodium dodecyl sulfate-polyacrylamide gel electrophoresis, UT-A was faint in early neonates and intensified at 15 days.(ABSTRACT TRUNCATED AT 250 WORDS)
mesh_terms: D000814:Aniline Compounds / Q000378:metabolism; D000818:Animals; D003577:Cytochrome P-450 Enzyme System / Q000032:analysis* / Q000096:biosynthesis; D004591:Electrophoresis, Polyacrylamide Gel; D004790:Enzyme Induction; D005260:Female; D005333:Fetus / Q000201:enzymology*; D006900:Hydroxylation; D007527:Isoenzymes / Q000032:analysis*; D008099:Liver / Q000201:enzymology*; D008297:Male; D008748:Methylcholanthrene / Q000494:pharmacology*; D008862:Microsomes, Liver / Q000201:enzymology; D010105:Oxygenases / Q000032:analysis*; D010634:Phenobarbital / Q000494:pharmacology*; D011247:Pregnancy; D051381:Rats; D011919:Rats, Inbred Strains; D012737:Sex Factors
chemical_list: D000814:Aniline Compounds; D007527:Isoenzymes; D008748:Methylcholanthrene; D003577:Cytochrome P-450 Enzyme System; D010105:Oxygenases; C023650:aniline; D010634:Phenobarbital