Different induction of gulonolactone oxidase in aromatic hydrocarbon-responsive or -unresponsive mouse strains

The role of aromatic hydrocarbon receptor (AhR)-mediated signal transductio n pathways was investigated in the regulation of ascorbate synthesis by usi ng Ah-responsive and Ah-unresponsive mouse strains. In vivo 3-methylcholant hrene treatment increased hepatic and plasma ascorbate concentrations only in the Ah-responsive strain. The mRNA level of gulonolactone oxidase and th e microsomal ascorbate production from p-nitrophenyl glucuronide, D-glucuro nic acid or gulonolactone in the liver of Ah-responsive and Ah-unresponsive mice were compared. In;ih-responsive mice, these parameters were higher or iginally, and they further increased upon in vivo addition of 3-methylchola nthrene, while in Ah-unresponsive mice the treatment was not effective. The se results suggest that the transcription of gulonolactone oxidase gene is regulated by an Ah receptor-dependent signal transduction pathway. (C) 1999 Federation of European Biochemical Societies.