Effect of ivermectin on activities of cytochrome P450 isoenzymes in mouflon (Ovis musimon) and fallow deer (Dama dama).
Ivermectin is an antiparasitic drug widely used in veterinary and human medicine. We have found earlier that repeated treatments of rats with high doses of this drug led to significant increase of cytochrome P450-dependent 7-methoxyresorufin O-demethylase (MROD) and 7-ethoxyresorufin O-deethylase (EROD) activities in hepatic microsomes. In the present study, the effects of ivermectin on cytochrome P450 (CYP) activities were investigated in mouflon (Ovis musimon) and fallow deer (Dama dama). This study was conducted also to point out general lack of information on both basal levels of CYP enzymes and their inducibilities by veterinary drugs in wild ruminants. Liver microsomes were prepared from control animals, mouflons, after single or repeated (six doses in six consecutive days) treatments with therapeutic doses of ivermectin (0.5 mg kg(-1) of body weight), and fallow deer exposed to repeated doses of ivermectin under the same conditions. Alkyloxyresorufins, testosterone and chlorzoxazone were used as the specific substrate probes of activities of the CYP isoenzymes. A single therapeutic dose of ivermectin significantly induced (300-400% of the control group) the activities of all alkyloxyresorufin dealkylases tested in mouflon liver microsomes. Repeated doses of ivermectin also caused an increase of these activities, but due to fair inter-individual differences, this increase was not significant. The administration of ivermectin led to an induction (170-210% of the control) of the testosterone 6beta- and 16alpha-hydroxylase activities in mouflon liver but no significant modulation of chlorzoxazone hydroxylase (CZXOH) activity was found in mouflon liver. CYP-dependent activities in hepatic microsomes were generally higher in fallow deer than in mouflons. However, with the exception of slight increase in the 7-benzyloxyresorufin O-dealkylase (BROD) activities, no significant modulation of the other activities was observed. The induction of CYP3A-like isoenzyme was confirmed by immunoblotting only in the microsomes from mouflons administered with repeated doses of ivermectin; however, no significant increase of CYP1A isoenzymes was observed due to a weak cross-reactivity of anti-rat CYP1A1/2 polyclonal antibodies used in the study. The results indicate that ivermectin should be considered as an inducer of several cytochrome P450 isoenzymes, including CYP1A, 2B and 3A subfamilies, in mouflons. The comparison of induction effect of ivermectin in rat, mouflon and fallow deer also demonstrates the inter-species differences in inducibility of CYP enzymes.
Skálová
L
L
Faculty of Pharmacy, Charles University, Heyrovského 1203, CZ-50005, Hradec Králové, Czech Republic.
Szotáková
B
B
Machala
M
M
Neca
J
J
Soucek
P
P
Havlasová
J
J
Wsól
V
V
Krídová
L
L
Kvasnicková
E
E
Lamka
J
J
D000818:Animals; D000871:Anthelmintics / Q000008:administration & dosage / Q000494:pharmacology; D001189:Aryl Hydrocarbon Hydroxylases; D002458:Cell Fractionation; D065727:Cytochrome P-450 CYP2C8; D065729:Cytochrome P-450 CYP2C9; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism*; D000072467:Cytochrome P450 Family 2; D003670:Deer / Q000378:metabolism*; D004790:Enzyme Induction; D006801:Humans; D015151:Immunoblotting; D007527:Isoenzymes / Q000378:metabolism; D007559:Ivermectin / Q000008:administration & dosage / Q000494:pharmacology*; D008862:Microsomes, Liver / Q000187:drug effects* / Q000201:enzymology; D015394:Molecular Structure; D012418:Ruminants / Q000378:metabolism*; D039181:Steroid 16-alpha-Hydroxylase; D013250:Steroid Hydroxylases / Q000378:metabolism
D000871:Anthelmintics; D007527:Isoenzymes; D007559:Ivermectin; D003577:Cytochrome P-450 Enzyme System; D013250:Steroid Hydroxylases; C450260:CYP2C9 protein, human; D065729:Cytochrome P-450 CYP2C9; D001189:Aryl Hydrocarbon Hydroxylases; C450279:CYP2C11 protein, rat; C450259:CYP2C8 protein, human; D065727:Cytochrome P-450 CYP2C8; D000072467:Cytochrome P450 Family 2; D039181:Steroid 16-alpha-Hydroxylase; C022724:testosterone 7-alpha-hydroxylase, hamster