CATALYTIC AND IMMUNOCYTOCHEMICAL DETECTION OF XENOBIOTIC-METABOLIZINGENZYMES IN THE OLFACTORY ORGAN OF RAINBOW-TROUT (ONCORHYNCHUS-MYKISS)

The fish olfactory organ, which is covered with a sensory epithelium, is in direct contact with aquatic pollutants. In mammals, presence of xenobiotic metabolizing enzymes has been reported in the olfactory epi thelium, but few studies have been carried out on this topic in fish. In the present study, xenobiotic metabolizing enzymes were investigate d in the rainbow trout olfactory organ. Data show that cytochrome P450 reductase, p-nitrophenol hydroxylase and glutathione S-transferase sp ecific activities were in the same range as that in the liver, whereas 7-ethoxyresorufin O-deethylase and 7-ethoxycoumarin O-deethylase spec ific activities were 80 and 30 times lower, respectively, in the olfac tory organ compared to the liver. Immuno-ecytochemical investigation s hows that cytochrome P4501A1 was located in both the epithelial non-se nsory cells and the basal cells of the sensory epithelium, as well as in goblet and microvilli cells of the non-sensory epithelium. The pres ence of such enzyme activities in the olfactory organ of rainbow trout addresses the question of their involvement in the detoxication/toxic ation of pollutants as well as in the olfactory function.