Biomonitoring of pollution: the hepatic cytochrome P-450 enzyme system in the feral mouse Apodemus flavicollis as indicator

The aim of the present study was to find a suitable wild-rodent to be used as terrestrial bioindicator. The wild mice were trapped at three sites around Vienna and at a fourth location in the countryside. Apodemus flavicollis, the yellow-necked mouse, was the most frequently captured mouse at all four sites. For each sample hepatic microsomal protein content, cytochromes b5 and P450, and enzyme catalytic activities-ECOD, EROD, BROD and PROD were measured. Except for one male urban group no significant differences between rural and urban groups in ECOD activity were observed. Increased cytochrome b5 and P450 contents per mg of microsomal protein were found in one of the male and all the three female urban groups. However the alkoxyresorufin O-dealkylase activities were significantly increased in both sexes of the three city groups. These results suggest that induction of cytochrome P450IA and P450IIB families has occurred in urban populations, indicating a possible pollution with halogenated dioxins and furans, PCBs, PAHs etc. The data show that induction of hepatic mixed function oxidase (HMFO) activity in the feral mouse Apodemus flavicollis can be successfully used as a terrestrial bioindicator for pollution monitoring.