Effects of avermectin on microsomal cytochrome P450 enzymes in the liver and kidneys of pigeons

•Avermectin exposure inhibited P450 enzyme system to the liver and kidney of pigeon.•Pathological changes in liver and kidney exposed to avermectin were obvious.•Avermectin injured the liver and kidney of pigeon in a dose-time-dependent pattern.

Residues of avermectin (AVM) drugs have toxic effects on non-target organisms. Analyses of cytochrome P450 enzymes are among the most frequently employed indicators in pharmacology and toxicology studies. In this study, the responses of cytochrome P450 enzymes and pathological changes in the liver and kidney tissues of King pigeons (Columba livia) following subchronic exposure to avermectin for 30, 60 and 90 d were investigated. Dose- and time-dependent decreases in the activities of P450 enzymes (i.e., aminopyrine-N-demethylase, erythromycin N-demethylase, aniline 4-hydroxylase and NADPH-cytochrome C reductase) and down-regulation of the P450 and b5 contents were observed. The microscopic structures were clearly altered, the severity of these alterations increased with the concentration of AVM and the exposure time. These results imply that AVM can inhibit the P450 enzyme systems in the liver and kidney tissues of pigeons. This research provides insight into the safe use of AVM and a comprehensive evaluation of the toxicological effects of AVM in birds.