Study On The Relationship Between Cardiac Injury And Mitochondrial Injury In Broilers Dead Of Sudden Death Syndrome

Sudden death syndrome in broilers is one of the important diseases that cause the death of commercial broilers.Most broiler strains are susceptible to the disease and can occur all the year round,so it has caused serious economic losses to broiler production.The etiology of SDS is very complex,related to many factors,the exact etiology and pathogenesis is not clear,but it is generally believed that SDS is a metabolic disease related to cardiac dysfunction in broilers.In SDS,the heart showed myasthenia and abnormal contraction,and ATP production decreased.This phenomenon suggests that mitochondrial dynamics may play a role in SDS.Mitochondria are highly dynamic organelles,known as intracellular "energy factories".Mitochondria maintain their normal function through continuous fusion-division.More than 90% of the energy in cardiomyocytes is provided by mitochondrial oxidative phosphorylation.in order to study the pathogenesis of sudden death syndrome in broilers,this study was carried out.In this experiment,broilers in good growth condition and sudden death were taken as the object of study(about 35 days old).The hearts were quickly removed and frozen with liquid nitrogen,fixed with formaldehyde and fixed with glutaraldehyde,respectively.(1)The myocardial tissue was fixed and paraffin sections were prepared for HE staining to observe the pathohistological changes of cardiomyocytes.(2)the ultrastructure of myocardial cells and mitochondria in sudden death broilers was observed by transmission electron microscope(TEM),and the ultrastructure of myocardial cells and mitochondria in sudden death broilers was observed by transmission electron microscope(TEM).(3)Detection of Drp1 and COX ? in cardiac myocytes of broilers by)Western blot.The mRNA transcription levels of adrenergic receptor ? 1,? 2 and ? 3 genes were detected by real-time PCR.To study the pathological mechanism of left heart in sudden death broilers.In order to further investigate the role of mitochondria in the process of sudden death of broilers,the experimental study was carried out at the cell level on the basis of(1)culturing primary cardiomyocytes and establishing the model of sudden death cardiomyocytes in broilers.Emphasis was placed on the mechanism of mitochondrial kinetics in the process of cardiomyocyte degeneration and injury in SDS broilers.(2)cardiomyocytes were exposed to 10 mM,20 mM and 40 mM lactic acid.the primary cardiomyocytes treated with lactic acid were observed by optical microscope and the viability of cardiomyocytes treated with lactic acid was detected by CCK8.(3)the structure and function of mitochondria in sudden death cardiomyocyte model were detected by apoptosis detection kit and mitochondrial membrane potential detection kit.The results were as follows:(1)HE histopathological results showed that compared with the control group,sudden death broiler cardiomyocytes had severe granular degeneration and a certain degree of focal necrosis,myocardial interstitial widening and fat infiltration.(2)the results of transmission electron microscope(TEM)showed that the myofibrils were arranged neatly,the sarcomere was intact,the mitochondrial structure was complete,and the mitochondrial cristae were dense in the left ventricular myocardium of normal heart;The myocardial cells of sudden death broilers were obviously swollen,and the arrangement of myofibrils was disordered and sparse.Most sarcomere disappeared;some myofibrils were broken and dissolved,forming blank dissolution foci;mitochondrial cristae dissolved and disappeared,and some mitochondria showed vacuolar changes.(3)the results of)Western blot showed that the expression of Drp1 protein in cardiomyocytes of sudden death broilers increased and the number of Drp1 with mitochondrial translocation increased.The results of real-time PCR showed that the expression of adrenergic receptor ? 1 and ? 2 in the control group was close to that in the sudden death group,but the expression of adrenergic receptor ? 1 and ? 2 in the sudden death group was similar to that in the sudden death group,but the expression of adrenergic receptor ? 1 and ? 2 in the sudden death group was similar.The amount of ? 3 decreased significantly and the expression of ? 3 increased significantly.The results showed that sudden death center failure occurred rapidly in broilers,and broilers died in the late stage of heart failure.(4)the primary cardiomyocytes were isolated and cultured.the morphology of the cells was observed by microscope and identified by ?-actin staining.The results showed that the positive rate of cardiomyocytes was more than 95%,which indicated that the primary cardiomyocytes were cultured successfully.(5)the primary cardiomyocytes were observed by optical microscope and the results of CCK8 detection after exposure to lactic acid showed that the primary cardiomyocyte model of sudden death broilers was successfully established.(6)the results of kit showed that cardiomyocytes apoptosis and mitochondrial membrane potential decreased.To sum up,sudden death broilers caused by insufficient cardiac energy supply,resulting in enhanced mitochondrial metabolism,breaking the dynamic balance of mitochondrial fusion and division,increased Drp1 expression,promoting mitochondrial division,mitochondrial fragmentation and fragmentation caused by the increase in mitochondrial fragmentation,mitochondrial fragmentation and mitochondrial fragmentation.In turn,the loss of cardiac function,heart failure occurs.Cardiomyocyte apoptosis,mitochondrial dynamic imbalance and so on.