Metabolomics analysis reveals the effects of high dietary copper on mitochondria-mediated autophagy and apoptosis in spleen of broiler chicken

Copper (Cu) is a necessary micro-element and plays important roles in many biochemical processes. However, excessive Cu intake can lead to multi-organ toxicity, especially in the spleen. To gain further insights into the specific mechanisms of splenic toxicity associated with Cu-induced metabolic disorders, 192 one-day-old chickens were selected and randomly divided into four groups for this study. The broilers were fed with diets containing Cu at final concentrations of 11, 110, 220 and 330 mg/kg for 49 days. The results showed that high dietary Cu caused nuclear shrinkage and mitochondrial vacuolization in the spleen and induced splenic injury through regulating the glutathione metabolism, pentose and gluconate interconversion, tryptophan metabolism and glycerophosphatidylcholine metabolism pathways. Moreover, excess Cu could disorder the mitochondrial dynamics via up-regulating the levels of Drp1, Parkin PINK1, and Dynein, and down-regulating the levels of Mfn1, Mfn2 and OPA1. Cu treatment increased the levels of LC3A, LC3B, mTOR, Beclin1, and ATG5 and decreased the p62 level to promote autophagy of splenocytes. Meanwhile, a high dose of Cu promoted splenocyte apoptosis by increasing the levels of p53, BAK-1, Bax, Cyt C and Caspase-3 and decreasing the level of Bcl-2. These results demonstrated that high dietary Cu could cause autophagy and apoptosis via inducing metabolic disturbances and disordering mitochondrial dynamics in the spleen of broiler chicken.