title: Influence of aging and poly IC treatment on xenobiotic metabolism in mice.
abstract: Cytochrome P-450-dependent and independent metabolism of xenobiotics in the liver of C57BL/10ScSn male mice was investigated in relation to age and the age-related differences in response to treatment with polyriboinosinic-polyribocytidylic acid (poly IC), an interferon inducing agent. Young (3 months), middle-aged (15 months) and old (27 months) animals were studied. Mean survival time of males of this strain is 30-33 months. Age-related changes in the metabolism of xenobiotics included significant decreases between middle and old age in activities of the microsomal P-450-dependent mixed function oxidases (MFO), aryl hydrocarbon hydroxylase (AHH) and p-nitroanisole (p-NA) O-demethylase, but not 7-ethoxycoumarin (7-Ec) O-deethylase. Analysis of P-450-independent enzymes revealed a significant decrease in the epoxide hydrolase activity in the microsomes and cytosol from old compared to middle-aged or young mice. Glutathione S-transferase activity towards 1-chloro-2,4-dinitrobenzene (CDNB) was lower in cytosols of middle-aged and old than young mice. Carboxylesterase activity was not altered by age. Hepatic microsomal protein content was significantly higher in middle-aged and old than in young mice. Intraperitoneal treatment with a single dose of 5 mg/kg poly IC 24 hours before sacrifice resulted, for mice of all age groups, in a marked inhibition of activities of all 3 microsomal cytochrome P-450-dependent enzymes, without any changes in activities of the P-450-independent enzymes. The inhibition of AHH by poly IC was much higher in old and middle-aged than in young mice, averaging 87.1%, 74.5%, and 41.9%, respectively, in the 3 age groups. Poly IC treatment increased lipid peroxidation in liver homogenates of all groups of mice. Body and liver weights were not altered in animals of the 3 age groups by poly IC treatment, but hepatic microsomal protein contents were significantly decreased.
mesh_terms: D000375:Aging; D000818:Animals; D003577:Cytochrome P-450 Enzyme System / Q000494:pharmacology; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008862:Microsomes, Liver / Q000201:enzymology; D006899:Mixed Function Oxygenases / Q000378:metabolism*; D011070:Poly I-C / Q000494:pharmacology*
chemical_list: D003577:Cytochrome P-450 Enzyme System; D006899:Mixed Function Oxygenases; D011070:Poly I-C