Toxic effects of copper on duck cerebrum: a crucial role of oxidative stress and endoplasmic reticulum quality control

Abstract

To study the effects of Cu overload on ER quality control in duck cerebrums, 144 ducks were treated with 8 mg/kg, 100 mg/kg, 200 mg/kg and 400 mg/kg Cu added in the feed for 45 days. From histopathological examination, we found that excessive Cu increased the amount of microglia and disintegrated neuron, decreased the number of Nissl bodies, perturbed nerve fibers in duck cerebrums. Cu poisoning also increased Cu, H₂O₂, T-SOD, and MDA levels, decreased Fe and CAT contents in duck cerebrums. Furthermore, Cu treatment upregulated the mRNA levels of the unfolded protein response genes (PERK, ATF6, and IRE1), ER-associated degradation genes (CNX, Derlin1, and Derlin2), autophagy genes (ATG5, ATG7, ATG10, Beclin1, LC3A, LC3B, and P62), and heat shock response genes (Hsp70 and Hsp90) in duck cerebrums; elevated the protein levels of p-PERK, CNX, SEL1L, Beclin1, P62, and LC3BII/LC3BI in duck cerebrums; increased the numbers of SEL1L and LC3B puncta in duck cerebrums. Thus, our data showed that excessive Cu could cause histopathological damage to duck cerebrums, disrupt the balance of the trace elements, induce oxidative stress and activation of ER quality control, thereby resulting in duck cerebrums damage.

Keywords: Autophagy; Cerebrum; Copper; ERAD; Endoplasmic reticulum; UPR.