Endogenous Functions and Expression of Cytochrome P450 Enzymes in Teleost Fish: A Review

Abstract

Environmental monitoring programs use biological tools in the form of pollutant-sensitive organisms called sentinel species and sub-organismic indicators or biomarkers to assess impacts to ecosystems by pollution. In this work, we review one of the more widely used groups of sentinel organisms by monitoring programs, the teleost fishes, and the best known biomarker of exposure, the cytochrome P450 superfamily of enzymes. We found that at least one P450 enzyme has been reported in 57 species of fish. Based on comparisons between enzymatic induction and endogenous function of P450, we discuss the specificity and sensibility of fish P450 enzymes as biomarkers in environmental monitoring. Studies in recent years show that the endogenous functions of several P450 enzymes in fishes are unknown, and, contrary to belief, the mechanisms of induction of the P450 enzymes in mammals and fishes are often different, and, thus, substrate-specific inductions are not comparable. It becomes clear that it is necessary to advance our understanding of P450 endogenous functions if we wish to correctly interpret the meaning of catalytic activity data of these mono-oxygenases for the purpose of environmental monitoring programs.