Changes in the Expression of MIF and Other Key Enzymes of Energy Metabolism in the Myocardia of Broiler Chickens with Ascites Syndrome

SIMPLE SUMMARY: Ascites syndrome (AS), a nutritional, metabolic disease in broiler chickens, exerts serious effects on the economic efficiency of the broiler industry. To date, the pathogenesis of broiler ascites syndrome is still not well understood. In this study, we explored the metabolic function of the right ventricles of clinical ascitic broilers and healthy broilers (control) from the same flock. Our study showed the myocardial energy supply in ascitic broiler chickens occurs mainly through glycolysis and fatty acid metabolism, and the oxidation of the TCA cycle is blunted. These findings suggest that there is insufficient energy metabolism in the right hearts of broilers with ascites syndrome, causing a state of functional failure. These results may provide useful information for elucidating the pathogenesis of broiler ascites syndrome and may also provide a reference for future research on similar diseases (including pulmonary hypertension syndrome and heart failure) in humans and domestic animals. ABSTRACT: Ascites syndrome (AS) is a metabolic disease observed mainly in fast-growing broilers. The heart is one of the most important target organs of the disease. The goal of this study was to evaluate the metabolic function of the right ventricles in clinical ascitic broilers. HE staining was performed to observe histopathological changes in the right ventricle of the heart, while Western blotting was used to detect the protein expression levels of macrophage migration inhibitory factor (MIF) and phosphorylated AMP-activated protein kinase (p-AMPK), as well as other key enzymes of energy metabolic pathways (i.e., glycolytic pathway: HK2, PFK1, PFK2, and PKM2; the tricarboxylic acid cycle (TCA cycle) pathway: OGDH, IDH2, and CS; and the fatty acid oxidation pathway: CPT-1A and ACC) in myocardial tissue. The histopathological examination of the myocardia of ascitic broilers revealed disoriented myocardial cells in the myofibril structure and a large number of blood cells deposited in the intermyofibrillar vessels, suggesting right heart failure in ascitic broilers. The Western blotting analysis demonstrated significantly increased levels of MIF and p-AMPK in the myocardia of ascitic broilers compared to those of the control group (p < 0.05). Additionally, the protein expression of key enzymes was dramatically increased in the glycolytic and fatty acid oxidation pathways, while the protein expression of key enzymes in the TCA cycle pathway was decreased in the ascitic broiler group. These findings suggest enhanced glycolysis and fatty acid oxidation metabolism, and a diminished TCA cycle, in the myocardia of broiler chickens with ascites syndrome.