Expression Of Proteins Related To Mitophagy And Mitochondrial Apoptosis In Myocardium Of Broilers With Pulmonary Hypertension

Pulmonary hypertension syndrome,also known as broiler ascites syndrome,is a commonly metabolic disease in broilers.The occurrence of this disease has caused serious economic losses in the poultry industry in our country.It was found that right heart failure was the important characferistic of pulmonary hypertension in broilers,and the function of mitochondria were damaged in right heart.However,the studies on mitophagy and apoptosis in cardiomyocytes during broiler pulmonary hypertension are rare.Therefore,the genes and proteins related to mitophagy and mitochondrial apoptosis were detected in the myocardium of broilers with pulmonary hypertension,which preliminarily discussed the influence of mitophagy and mitochondrial apoptosis in the myocardium of broilers with pulmonary hypertension and laid the foundation for further expanding the pathogenesis of pulmonary hypertension in broilers.In this experiment,120 1-day-old white-feather broilers were selected and divided into two groups,e.g.with 30 broilers in control group and 90 broilers in experimental group.At the 20th day of age,0.35 mL cm-32 ion-exchange cellulose suspension(0.02 g/mL cellulose and 150 U/mL heparin)was intravenously injected 0.35 mL into the wing vein,which induced ascites syndrome in experimental broilers.In control group,30 broilers were injected with normal saline of the same volume through the wing vein at the age of 20 days.The broilers were anesthetized and sacrificed at the age of 42 days,and the hearts were collected.The experimental group was divided into subclinical group and pathogenesis group according to ascites index.The structure and pathological changes of myocardial tissue was observed by optical microscope.Additionally,the mRNA expressions of mitophagy-related genes(Parkin,PINK1,LC3-II,LC3-I,p62,and NIX)and mitochondrial apoptosis-related genes(Caspase3,Bak1,Bax,Bcl-2,CytC and p53)were determined by fluorescence quantitative PCR.Furthermore,the expression levels of mitophagy-related proteins(LC3-II/LC3-I,p62 and Parkin)and mitochondrial apoptosis-related proteins(Caspase3 and CytC)were detected by western-blot.Moreover,the expression and localization of LC3-II,p62 and Parkin were detected by immunohistochemistry in myocardial tissue.The results are as follows:(1)The myocardial structure in control group was clear,and mild myocardial degeneration occurred in the subclinical group,and severe myocardial degeneration occurred in the morbidity group,accompanied by hemorrhage and inflammatory tissue infiltration.(2)Compared with the control group,the mRNA expression level of autophagy-associated gene(Parkin,PINK1,LC3-II,NIX,)and the protein expression of Parkin and LC3-II/LC3-I in myocardial mitochondria in the subclinical group and the onset group showed an increasing trend,and it was significantly higher in the onset group than that in the control group.The mRNA expression of p62,LC3-I and the protein expression of p62 showed a decreasing trend,and the protein expression of p62 was significantly decreased in the disease group than that in the control group(P< 0.05).(3)Compared with the control group,the mRNA expression levels of caspase3,Bak1,Bax,CytC,p53 and the protein expression levels of Caspase3 and CytC in the subclinical group and the onset group showed a tendency to increase,the mRNA expression of Bcl-2 in the course of the disease was decreased.The results showed that mitophagy and myocardial apoptosis may be involved in the pathogenesis of pulmonary hypertension in broilers.