Hepatic phenylalanine hydroxylase of bank voles Clethrionomys Glareolus Schreber as a biomarker of pollution

In order to identify some novel parameters for monitoring the environmental impact of industrial pollutants, we measured the hepatic phenylalanine hydroxylase activities of two species of feral rodent: the bank vole Clethrionomys glareolus and field mouse Apodemus sylvaticus trapped at two isolated rural areas (reference sites) and at a study site adjacent to a bauxite refinery where atmospheric sulphur dioxide levels are high. At the reference sites voles showed lower-specific activity for the enzyme than mice. There was no difference in activities between mice from contaminated and reference sites. However, reference enzyme activities of both male and female voles were lower at the contaminated site, and males showed severe diminution of hepatic tetrahydrobiopterin-dependent phenylalanine hydroxylase (27% of reference values). Western blotting revealed normal abundance of phenylalanine hydroxylase protein, indicating loss of catalytic function, Loss of activity may be due to oxidative stress resulting from an accompanying deficiency in glutathione peroxidase activity, which for voles of both sexes at the contaminated site was half that of the references. The differences between mice and voles are discussed. These two enzymes in bank voles may provide useful bioindicators of the impact of industrial pollutants.