Submitted to: Experimental Biology
Publication Type: Abstract Only
Publication Acceptance Date: 1/20/2006
Publication Date: 3/6/2006
Citation: Proszkowiec-Weglarz, M., Richards, M.P. 2006. Expression of AMP-activated protein kinase pathway genes in the chicken brain during fasting and refeeding [abstract]. The FASEB Journal. 20:A171. Abstract Number 131.7.
Technical Abstract: AMP-activated protein kinase (AMPK) is a heterotrimeric enzyme complex composed of one catalytic (alpha) and two regulatory (beta and gamma) subunits. AMPK plays a key role in maintaining intracellular energy homeostasis and, on the whole animal level, in regulating energy balance and food intake. Once activated by phosphorylation, AMPK phosphorylates a variety of protein targets that influence carbohydrate, protein, and lipid metabolism. The aim of this study was to investigate the AMPK pathway in the avian brain. In broiler chickens, the brain preferentially expressed alpha-1, beta-2, gamma-1 and gamma-2 AMPK subunit mRNA transcripts. During changes in energy state (24-48 h fast followed by 24 h of refeeding) we did not observe any major changes in AMPK subunit mRNA levels in the whole brain or in the hypothalamus nor was AMPK activity (phosphorylation state as measured by Western blot) changed significantly in whole brain. Immunocytochemical analysis of the brain confirmed the presence of active (phosphorylated) AMPK, especially in those hypothalamic nuclei involved in the regulation of food intake. During fasting mRNA levels of fatty acid synthase and acetyl-CoA carboxylase did not change in whole brain, whereas they decreased significantly in the hypothalamus. The expression level of malonyl-CoA decarboxylase decreased in whole brain as well as in hypothalamus during fasting. Neuropeptide Y mRNA levels in the hypothalamus increased, while proopiomelanocortin levels declined. Together, these results suggest that AMPK, expressed in the brain and especially in hypothalamus of chickens, may play a role in regulating energy balance and food intake.