For example, stearate and palmitate were lower in both fasted and insulin neutralized compared to fed birds. While the purpose of our study design was to determine the specific effects of insulin on chicken adipose tissue, we cannot exclude the possibility that some of the overlapping changes in gene expression were secondary to systemic factors, Inhibitors,Modulators,Libraries such as hypergluca gonemia present in both treatment groups. In vitro experiments using primary adipocytes or adipose explants will be useful to confirm specific effects of insu lin on genes identified herein. Of the 13 Inhibitors,Modulators,Libraries changes in expression that were unique to insulin neutralization, the most interesting responses were up regulation of GCG, which encodes preprogluca gon, and down regulation of the glu cagon receptor.

The proglucagon system in avians is more complex than in mammals. The avian preproglucagon Entinostat locus encodes two distinct precursor proteins that yield different peptides through alternative posttranslational processing, the class A transcript yields glucagon and glucagon like peptide 1, while the class B transcript additionally produces glucagon like peptide 2 and is more like the mammalian transcript. Adipose tissue expresses both transcripts, with PGA being slightly more abundant, and is the third highest preproglucagon expressing tissue in chicken, be hind pancreas and the proventriculus. We used transcript specific QPCR to determine that only the PGB transcript was up regulated by insulin neutralization.

Additional experiments are necessary to delineate which of the encoded peptides are up regulated in parallel, but the coincident down regulation of the glucagon receptor suggests a paracrine glucagon axis in chicken adipose tissue, and one that is regulated by insulin. In support of this concept, plasma glucagon was elevated comparably Inhibitors,Modulators,Libraries in both treatment groups, while GCG expression Inhibitors,Modulators,Libraries in adipose tissue was only up regulated by in sulin neutralization. Tissue metabolomic analysis highlighted effects of in sulin neutralization that were divergent from fasting and not readily apparent from microarray data. Most of the tissue amino acids that were measured were higher with insulin neutralization but lower with fasting when each group was compared to ad libitum fed controls. This pattern parallels the levels of NH2NPN levels in blood.

Low levels in fasted adipose tissue were most likely due to oxidation of the carbon skeletons for cellular en ergy through the tricarboxylic acid cycle cycle and or for glyceroneogenesis, in the absence of dietary glucose. Increased amino acid catabolism was reflected in the differential expression profiles of the fasted vs. fed comparison. In the insulin neutralized group, however, glucose supply from food was maintained and preferentially oxidized for energy.