Cytochrome P450-dependent monooxygenase activities and their inducibility by classic P450 inducers in the liver, kidney, and nasal mucosa of male adult ring-necked pheasants.
In this study, several P450-dependent monoxygenase activities in the liver, kidney, and nasal mucosa of ring-necked pheasants were examined. In addition, the presence and inducibility of P450 isoenzymes in the hepatic and renal tissues of pheasants were examined by using typical substrates and inducers of P450s along with polyclonal antibodies raised against mammalian isoforms. Anti-rat P450 1A1 recognized in microsomes of both pheasant liver and kidney a protein that was markedly induced by beta-naphthoflavone and accompanied by an increase of various monooxygenases, in particular, methoxyresorufin-O-demethylase (MROD) activity. Anti-rat P450 2E1 revealed in microsomes of the pheasant liver but not in kidney an immunoreactive protein that was slightly induced by acetone but not accompanied by an increase of para-nitrophenol hydroxylase activity. On the other hand, acetone treatment caused an induction of other hepatic monoxygenases including MROD, erythromycin N-demethylase, and 6beta-testosterone hydroxylase. These two latter activities, known to be markers for 3A isoenzymes in rodents, were also enhanced in pheasant liver by phenobarbital but not by dexamethasone. The treatment with these two inducers also lacked to point out hepatic and renal proteins immunorelated to P450 3A or 2B subfamily, suggesting that these isoforms may be not expressed in pheasant. On the other hand, anti-rat P450 2C11 recognized two immunorelated proteins in the liver of both control and treated pheasants. The treatment with clofibrate, a mammalian inducer of 4A subfamily, induced both in liver and kidney of pheasant: i) a protein that cross-reacted with anti rat P450 4A1 and ii) the (omega) and (omega-1) lauric acid hydroxylase activities, known to be associated in mammals to this P450 subfamily. In the nasal mucosa of pheasant, a protein immunorelated to P450 2A and some monooxygenase activities (i.e., 7-ethoxycoumarin O-deethylase) linked, in mammals, to this isoform have been found; by contrast a protein immunoreactive with anti P450 2G1 was not found. In conclusion, the immunochemical properties and monooxygenase activities of constitutive and inducible P450s in pheasants were different not only from those of mammals but also from those of chickens. The findings of the present work also suggest that the P450 induction profiles might provide a potential biomarker of pheasant exposure to chemicals or environmental pollutants in the wild-field or in the stock-farm.
Giorgi
M
M
Laboratory of Genetic and Biochemical Toxicology, Istituto di Mutagenesi e Differenziamento, Area della Ricerca CNR, via San Cataldo, Pisa, 56100, Italy.
Marini
S
S
Longo
V
V
Mazzaccaro
A
A
Amato
G
G
Gervasi
P G
PG
D000096:Acetone / Q000494:pharmacology; D000818:Animals; D001717:Birds / Q000378:metabolism*; D002994:Clofibrate / Q000494:pharmacology; D003577:Cytochrome P-450 Enzyme System / Q000096:biosynthesis*; D003907:Dexamethasone / Q000494:pharmacology; D004790:Enzyme Induction; D007668:Kidney / Q000187:drug effects / Q000201:enzymology*; D008862:Microsomes, Liver / Q000187:drug effects / Q000201:enzymology*; D009297:Nasal Mucosa / Q000187:drug effects / Q000201:enzymology*; D010634:Phenobarbital / Q000494:pharmacology; D019324:beta-Naphthoflavone / Q000494:pharmacology
D000096:Acetone; D019324:beta-Naphthoflavone; D003907:Dexamethasone; D003577:Cytochrome P-450 Enzyme System; D002994:Clofibrate; D010634:Phenobarbital