Effects of fatty liver hemorrhagic syndrome on the AMP-activated protein kinase signaling pathway in laying hens

Abstract

In mammals, the AMP-activated protein kinase (AMPK) pathways in the central and peripheral tissues coordinately integrate inputs from multiple sources to regulate energy balance. To investigate the effects of the fatty liver hemorrhagic syndrome (FLHS) caused by high-energy, low-protein diets and to explore the potential role of AMPK in the energy homeostasis of FLHS, 60 laying hens were equally divided into 2 groups: control group (basal diet) and experimental group (high-energy, low-protein diet). Liver tissues were subjected to histopathological analysis. Liver tissues were also collected on the 100th day to determine the levels of total cholesterol, triglyceride (TG), high-density lipoprotein cholesterol (HDL-Ch), low-density lipoprotein cholesterol (LDL-Ch), aspartate aminotransferase, and alanine aminotransferase in plasma. Additionally, the mRNA expression levels of AMPK signaling pathway related genes in liver were determined by quantitative RT-PCR. The results showed that histopathological lesions presented different degrees of lipid vacuolization in hepatocytes. In combination with hematoxylin and eosin and oil red O staining, the experimental group was divided into mild group and severe group. In the severe group, contents of TG and LDL-Ch were extremely significantly increased (P < 0.01) compared to the control group, and HDL-Ch content was extremely significantly decreased (P < 0.01). The serine-threonine kinase 11 and AMPKα1 mRNA expression levels were downregulated, while acetyl-CoA carboxylase, fatty acid synthase, hepatocyte nuclear factor-4α, 3-hydroxy-3-methyl glutaryl coenzyme A reductase and carnitine palmitoyltransferase-I mRNA expression levels were upregulated by a high-energy and low-protein diet. Taken together, these findings suggest that a functional AMPK signaling pathway exists in chickens and AMPK may alter the energy balance in the FLHS induced by high-energy, low-protein diets.