Autophagy is upregulated in brain tissues of pigeons exposed to avermectin

Avermectin (AVM) is used in agriculture and veterinary medicine for the prevention of parasitic diseases; AVM is the active component of some insecticidal and nematicidal products. Residues of AVM drugs or their metabolites in livestock feces have toxic effects on non-target aquatic and terrestrial organisms. In this study, changes in the levels of autophagy related genes and ultrastructure in pigeon brain tissues after subchronic exposure to AVM for 30, 60 and 90 d were investigated. The decrease in the mRNA levels of TORC1 and TORC2 and increase in the mRNA levels of LC3, Beclin 1, Dynein, ATG5 and ATG4B and the increase in the protein levels of LC3, Beclin 1 and Dynein in a dose- and time-dependent manner in the pigeon brain were observed. The number of autophagic vacuoles in the cerebrum, cerebellum and optic lobe increased significantly with the concentration of AVM and the exposure time. We found that the changes in the levels of autophagy related genes and the ultrastructure in the cerebrum were more obvious than in the cerebellum and the optic lobe. The results suggest that AVM could induce autophagy in pigeon brain tissues. The information presented in this study is helpful for understanding the mechanism of AVM-induced autophagy in birds.