title: [Induction of cytochrome P-450 forms in liver microsomes of rats in the early neonatal period after administration of phenobarbital and 3-methylcholanthrene].
abstract: The activity of cytochrome P-450 dependent monooxygenase system from rat liver microsomes after induction by phenobarbital and 3-methylcholantrene in early neonatal period (3-16 days after birth) was studied. It was found that the total amount of cytochrome P-450 increases after injection of these inducers in neonatal rats of all age groups. In parallel, in the case of 3-methylcholantrene induction the benz(a)pyrene hydroxylase and 7-ethoxyresorufin deethylase activities increase; phenobarbital induction causes a rise in the benzphetamine-N-demethylase and benz(a)pyrene hydroxylase activities. Immunochemical analysis involving the use of antibodies specifically directed against cytochrome P-450 of adult rats revealed that the level of cytochrome P-450 in the case of 3-methylcholantrene induction increases from 5 to 50%, whereas that of cytochrome P-450 upon phenobarbital induction increases from 5 to 40% in liver microsomes of 3- and 16-day-old rats. The mode of inhibition of various substrates metabolism by antibodies in neonatal rat microsomes suggests that the 3-methylcholantrene-induced cytochrome P-448, like in adult rats, participates in the hydroxylation of benz(a)pyrene and O-deethylation of 7-etoxyresorufin. The participation of phenobarbital-induced cytochrome P-450 in the metabolism of benzphetamine and aldrin in neonatal rats is much lower than in the adult ones. The metabolism of benz(a)pyrene in phenobarbital-induced neonatal rat microsomes in all age groups is not inhibited by antibodies. The age-dependent differences in inhibition of metabolism and the increase in the benz(a)pyrene hydroxylase activity in phenobarbital-induced rats suggest that the spectrum of inducible forms of cytochrome P-450 in neonatal rats differ from that in adult animals.
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D001564:Benzo(a)pyrene / Q000378:metabolism; D019388:Cytochrome P-450 CYP1A2; D003577:Cytochrome P-450 Enzyme System / Q000096:biosynthesis*; D003580:Cytochromes / Q000096:biosynthesis; D004790:Enzyme Induction / Q000187:drug effects; D008748:Methylcholanthrene / Q000494:pharmacology*; D008862:Microsomes, Liver / Q000201:enzymology*; D010634:Phenobarbital / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains
chemical_list: D003580:Cytochromes; D001564:Benzo(a)pyrene; D008748:Methylcholanthrene; D003577:Cytochrome P-450 Enzyme System; C017170:Cyp1a2 protein, rat; D019388:Cytochrome P-450 CYP1A2; D010634:Phenobarbital
vernacular_title: Issledovanie induktsii tsitokhroma P-450 mikrosom pecheni krys rannego neonatal'nogo perioda pri vvedenii fenobarbitala i 3-metilkholantrena.