title: Development of liver microsomal oxidations in the chick.
abstract: 1. Liver microsomal preparations from chick embryos (1 day before hatching) and from 1-7 day old chicks were assayed for oxidative drug-metabolizing activity with aminopyrine, aniline and naphthalene as substrates. 2. Activities for all three substrates were highest in preparations from 1 day-old chicks. These were more than twice as active as the 7 day-old preparations and about three times as active as those from the embryos. 3. The increase in drug-metabolizing activities in newly-hatched chicks was the same for either sex and persisted for 3 days before declining towards the 7 day-old levels. 4. The developmental time-course fo the liver microsomal drug-metabolizing activities was independent of any factor in the 105 000 g supernatant fractions and of such microsomal parameters as cytochrome b5 and cytochrome P-450 content, and NADPH-cytochrome c reductase activity, but was related to changes in NADPH-cytochrome P-450 reductase levels. 5. Treatment of 7 day-old chicks with exogenous inducers, 3-methylcholanthrene or phenobarbital sodium (100 mg/kg, intraperitoneally) brought about maximal stimulation of microsomal activity as 18-24 h. The time-course of this induction was reflected by changes in microsomal cytochrome P-450 content and NADPH-cytochrome P=450 reductase activities. 6. Some induction of  liver microsomal drug metabolism in 7 day-old chicks could also be brought about by injecting certain lipid-soluble egg yolk extracts.
mesh_terms: D000375:Aging; D000633:Aminopyrine N-Demethylase / Q000378:metabolism*; D000815:Aniline Hydroxylase / Q000378:metabolism*; D000818:Animals; D002645:Chickens; D003577:Cytochrome P-450 Enzyme System / Q000096:biosynthesis; D003580:Cytochromes / Q000096:biosynthesis; D004790:Enzyme Induction / Q000187:drug effects; D005260:Female; D008099:Liver / Q000254:growth & development*; D008297:Male; D008748:Methylcholanthrene / Q000494:pharmacology; D008862:Microsomes, Liver / Q000187:drug effects / Q000201:enzymology*; D006899:Mixed Function Oxygenases / Q000378:metabolism*; D010089:Oxidoreductases, N-Demethylating / Q000378:metabolism*; D010634:Phenobarbital / Q000494:pharmacology; D012737:Sex Factors
chemical_list: D003580:Cytochromes; D008748:Methylcholanthrene; D003577:Cytochrome P-450 Enzyme System; D006899:Mixed Function Oxygenases; D000815:Aniline Hydroxylase; D010089:Oxidoreductases, N-Demethylating; D000633:Aminopyrine N-Demethylase; D010634:Phenobarbital