Effect of Ethanol Diet on the circulating levels of Myonectin and Irisin

In this study, we aimed to characterize the link between ethanol consumption and the circulating levels of novel muscle‐produced secreted factors, or myokines. Myonectin (also known as C1q/TNF‐related protein 15) and irisin, the secretory product derived from Fibronectin type III domain‐containing protein 5 (FNDC5) are newly discovered myokines with wide‐ranging effects upon metabolism, inflammation, and tissue survival‐signaling. Alcoholic fatty liver disease (AFLD) is a major co‐morbidity associated with excess alcohol consumption and the leading cause of cirrhosis and liver‐related deaths in the world. AFLD occurs when excess alcohol consumption leads to disruptions in hepatic lipid metabolism resulting in the excess accumulation of lipids in in the liver. Due to the potential role in the activation of hepatic lipid oxidation induced by myonectin and irisin we hypothesized that chronic alcohol consumption will result in reduced circulating myonectin and irisin levels, which would be a potential mechanism for the excessive lipid accumulation. To test this hypothesis, serum was collected from female mice after 6‐weeks of ethanol feeding (Lieber‐Decarli alcohol diet, 5% ETOH by volume) or calorically matched control diet. Our data demonstrated that neither serum levels of myonectin or irisin were reduced in the ethanol‐fed mice. Myokines can control a number of inflammatory and metabolic responses including reducing levels of free fatty acids and lead to the uptake of fatty acids in various tissues such as adipocytes and hepatocytes. Although, our data demonstrate that lower myokine levels were are not associated with ALFD, it remains to be determine whether increasing the levels of these myokines could stimulate lipid metabolism and prevent AFLD.