Down-regulation of CYP1A2 induction during the maturation of mouse cerebellar granule cells in culture: role of nitric oxide accumulation.
Nitric oxide (NO) is responsible for cytochrome P450 (CYP450) loss during isolation and cytokine treatment of primary rat hepatocytes. As P450s mediate the metabolism of toxic chemicals, their inhibition could compromise the cells competence to eliminate toxins, a condition potentially relevant in neurological diseases involving constitutive activation of nitric oxide synthase (NOS) and NO over-production. Here, we have investigated the correlation between NO accumulation and CYP1A2 down-regulation during maturation of mouse cerebellar granule cells (CGC). As neurons matured in culture, the inducible levels of CYP1A2 protein and catalytic activity decreased to almost undetectable values. In parallel, a significant increase in NO concentration was observed. Neuronal NOS remained constitutively active during maturation, thus contributing to NO accumulation. The NOS inhibitor l-NAME, restored CYP1A2 catalytic activity up to 9 days in vitro, supporting a role for NO in the inhibition process. Maturation was also followed by increased NMDA receptor activity and intracellular Ca2+ concentration. We suggest that maintained NOS activity during CGC maturation could lead to NO accumulation and to decreased CYP1A2 inducibility. Increased NMDA receptor activity and Ca2+ entry could contribute to this process. Thus, neurodegeneration could diminish the induction of specific P450s and impair the metabolism of foreign and/or endogenous chemicals in the CNS.
Mulero-Navarro
Sonia
S
Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias, Universidad de Extremadura, 06071-Badajoz, Spain.
Santiago-Josefat
Belen
B
Pozo-Guisado
Eulalia
E
Merino
Jaime M
JM
Fernandez-Salguero
Pedro M
PM
D000375:Aging; D000814:Aniline Compounds / Q000378:metabolism; D000818:Animals; D000831:Animals, Newborn; D000001:Calcimycin / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism; D002478:Cells, Cultured; D016922:Cellular Senescence / Q000502:physiology*; D002531:Cerebellum / Q000166:cytology*; D002956:Citrulline / Q000378:metabolism; D019327:Copper Sulfate / Q000494:pharmacology; D019388:Cytochrome P-450 CYP1A2 / Q000096:biosynthesis*; D004268:DNA-Binding Proteins / Q000378:metabolism; D016291:Dizocilpine Maleate / Q000494:pharmacology; D015536:Down-Regulation; D004790:Enzyme Induction; D004791:Enzyme Inhibitors / Q000494:pharmacology; D018690:Excitatory Amino Acid Agonists / Q000494:pharmacology; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D005452:Fluoresceins / Q000378:metabolism; D007476:Ionophores / Q000494:pharmacology; D051379:Mice; D008810:Mice, Inbred C57BL; D016202:N-Methylaspartate / Q000494:pharmacology; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D009474:Neurons / Q000187:drug effects / Q000378:metabolism*; D009569:Nitric Oxide / Q000502:physiology*; D019001:Nitric Oxide Synthase / Q000378:metabolism; D012333:RNA, Messenger / Q000096:biosynthesis; D012097:Repressor Proteins / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D013997:Time Factors; D014316:Tritium / Q000378:metabolism; D014966:Xanthenes / Q000378:metabolism
D000814:Aniline Compounds; D004268:DNA-Binding Proteins; D004791:Enzyme Inhibitors; D018690:Excitatory Amino Acid Agonists; D018691:Excitatory Amino Acid Antagonists; D005452:Fluoresceins; D007476:Ionophores; D012333:RNA, Messenger; D012097:Repressor Proteins; D014966:Xanthenes; D014316:Tritium; C029569:diacetyldichlorofluorescein; C059715:Fluo-3; D002956:Citrulline; D009569:Nitric Oxide; D000001:Calcimycin; D016202:N-Methylaspartate; D016291:Dizocilpine Maleate; D019001:Nitric Oxide Synthase; D019388:Cytochrome P-450 CYP1A2; D019327:Copper Sulfate; D002118:Calcium; D019331:NG-Nitroarginine Methyl Ester