Fasting and Glucagon Stimulate Gene Expression of Pyruvate Dehydrogenase Kinase 4 in Chickens

The excessive accumulation of body fat has become a serious problem in the broiler industry. However, the molecular mechanisms underlying the regulation of lipid metabolism-related genes in broiler chickens are not fully understood. In the present study, we investigated the role of glucagon on the expression of lipid metabolism-related genes in chicken white adipose tissue (WAT). Four hours of fasting significantly increased plasma levels of free fatty acid in broiler chickens. The mRNA levels of adipose triglyceride lipase (ATGL) and pyruvate dehydrogenase kinase 4 (PDK4) in abdominal WAT significantly increased by fasting, whereas the mRNA levels of diacylglycerol O-acyl-transferase homolog 2 (DGAT2) and peroxisome proliferator-activated receptor-γ (PPARγ) significantly decreased. The results suggest that fasting stimulates lipolysis and suppresses adipogenesis and re-esterification of TG in chicken WAT. Glucagon significantly increased the mRNA levels of PDK4 in chicken primary adipocytes, whereas there were no significant changes in the mRNA levels of ATGL, DGAT2, and PPARγ. Our findings suggest that glucagon upregulates PDK4 expression and may stimulate lipolysis without affecting the expression of ATGL in chicken WAT.