Effects Of High Dietary Copper On Oxidative Damage And Autophagy In Hypothalamus Of Broilers

Copper is one of the most important trace element in all kinds of life,and the constituent of many proteins,which participates in many metabolic process.As a common feed additive,copper is overused in the breeding industry.The environmental pollution and animals products of high copper level were caused in food safety issues,which has caused widespread concern.Previous studies have shown that high copper can lead to changes in the expression levels of a series of hormones regulated by the hypothalamus in broilers.However,the effects of copper on the oxidative damage and autophagy of hypothalamus in chickens remains unclear.The experiment was conducted to investigate the effects of copper on the oxidative damage and autophagy of hypothalamus,which could provide theory for further investigation with effects of copper on pathological injury in broilers.Two hundred and forty one-day-old healthy Arbor Acres broiler were divided randomly into four groups,each of 60 birds.Copper content of basal diet of control group was 11 mg/kg according to the Feedstuff recommendation,and the copper content of experimental high copper group was 10,20,30 times of control group,i.e 110 mg/kg(high copper group I),220 mg/kg(high copper group II),330 mg/kg(high copper group III).The experimental period lasted for 49 days.The weight of each broilers was measured and the samples were collected at 1 weeks of 1,3,5,7 after administration respectively.After49 days,pathological changes were observed by optical microscope.Total antioxidant capacity(T-AOC),catalase(CAT),and superoxide dismutase(SOD)activities and malondialdehyde(MDA)content of hypothalamus of broilers were detected.A part of the tissue prepared to determine the content of copper by flame atomic absorption spectrometry.The mRNA expression of autophagy-related genes(Beclin1?LC3-I?LC3-II?dynein?Atg5?P62 ? mTOR)were detected by fluorescence quantitative PCR.Western-Blot,immunofluorescence staining and immunohistochemical were used to detect the location and expression of LC3 and Beclin1.The experimental results showed that:(1)With the increase of dietary copper concentrations,the weight gain of broilers increased firstly and then decreased.(2)With the increase of dietary copper concentrations,T-AOC,SOD,CAT activities were increased and then decreased,MDA was decreased and then increased.(3)The histopathological changes of hypothalamus in broilers of high copper groups were slight edema and vesicular degeneration.(4)Compared with the control group,the content of copper of broilers hypothalamus was increased firstly and then decreased.(5)With the increase of copper content in the high-copper diet,the mRNA expression of Beclin1,LC3,Atg5,dynein were significantly increased,the mRNA expression of mTOR and P62 were significantly decreased.The expression of Beclin1 and LC3 protein increased,and their positive neurons were accumulated in the hypothalamus.The results demonstrated that the dietary copper content of 220 mg/kg and below could increased broilers hypothalamus antioxidant capacity and autophagy.The diet copper content of 330 mg/kg might inhibit broiler weight gain and cause broilers oxidative damage and autophagy in hypothalamus.