Effects of in vitro and in vivo avermectin exposure on alpha synuclein expression and proteasomal activity in pigeons

•Avermectins (AVM) increased alpha synuclein in pigeon neurons.•Decreases in the proteasomal activity were observed in brain after AVM exposure.•The normal physiological function of proteasome could be inhibited by AVM.

Avermectins (AVMs) are used worldwide in agriculture and veterinary medicine. Residues of avermectin drugs, causing toxicological effects on non-target organisms, have raised great concern. The aim of this study was to investigate the effects of AVM on the expression levels of alpha synuclein (α-Syn) and proteasomal activity in pigeon (Columba livia) neurons both in vivo and in vitro. The results showed that, the mRNA and protein levels of α-Syn increased in AVM treated groups relative to control groups in the cerebrum, cerebellum and optic lobe in vivo. Dose-dependent decreases in the proteasomal activity (i.e., chymotrypsin-like, trypsin-like and peptidylglutamyl peptidehydrolase) were observed both in vivo and in vitro. The results suggested that AVM could induce the expression levels of α-Syn and inhibit the normal physiological function of proteasome in brain tissues and neurons. The information presented in this study is helpful to understand the mechanism of AVM-induced neurotoxicology in birds.