title: The ontogeny of nuclear aryl hydrocarbon hydroxylase.
abstract: The ontogeny of rat liver nuclear aryl hydrocarbon hydroxylase (AHH) ws studied. AHH which was barely detectable in 18--20 day fetal rat liver nuclei increased rapidly post-partum reaching a value which was over 200 times greater than the fetal liver specific activity. Nuclear AHH was induced upon administration of 3-methylcholanthrene (3-MC) to rats. The level of induction was dependent upon the age of the rat. Thus, the highest induced nuclear AHH specific activity was observed in the 3--4-week-old rat, i.e., 50--70 g in weight. The greatest fold increase in nuclear AHH after 3-MC administration was observed in the 6--8 g, or 1--2-day-old rat. Fetal rat liver nuclear AHH was also induced after 3-MC administration to the dam. The basal and induced levels of AHH were compared in nuclei and microsomes from 1--2 and 10--12-day-old rats. In the former, the ratio of the microsomal to nuclear AHH was 1.4 and 1.8 under basal and induced conditions, respectively.
mesh_terms: D000375:Aging; D000818:Animals; D000831:Animals, Newborn; D001189:Aryl Hydrocarbon Hydroxylases / Q000378:metabolism*; D002467:Cell Nucleus / Q000201:enzymology; D004790:Enzyme Induction; D005260:Female; D005333:Fetus / Q000201:enzymology; D066298:In Vitro Techniques; D008099:Liver / Q000201:enzymology* / Q000648:ultrastructure; D008297:Male; D008748:Methylcholanthrene / Q000494:pharmacology; D008862:Microsomes, Liver / Q000201:enzymology; D051381:Rats
chemical_list: D008748:Methylcholanthrene; D001189:Aryl Hydrocarbon Hydroxylases