Both chicken and mammalian adipocytes develop through a sequence of molecular triggers including activation of CCAAT enhancer binding protein alpha and per oxisome proliferator Inhibitors,Modulators,Libraries activated receptor gamma. A clear point of divergence, however, is their respon siveness to insulin. Unlike in mammals, insulin has min imal effect on glucose uptake in chicken adipose tissue. In fact, an avian homolog of the insulin sensitive glu cose transporter GLUT4 has not been identified in the current chicken genome database. Insulin does, however, stimulate uptake of acetate, which is the preferred substrate for de novo lipogenesis in Inhibitors,Modulators,Libraries chicken adipocytes, although the magnitude of the effect is relatively modest. Insulin signaling appears to proceed through tissue specific cas cades in chicken metabolic tissues.

In liver, insulin elicits a signaling cascade that parallels Brefeldin_A Inhibitors,Modulators,Libraries the response in mammals, including tyrosine phosphorylation of insulin receptor B subunit, insulin receptor substrate 1 and Src homology 2 domain containing substrate and ac tivation of phosphatidylinositol 3 kinase. The situation in skeletal muscle is more complex. Tyrosine phosphorylation of IRB and IRS 1 and PI3K activity are not regulated by insulin, whereas events downstream of PI3K are accordingly sensitive. We recently reported that insulin also does not elicit a classical IRB initiated cascade in chicken adipose tissue, in cluding the downstream steps of Akt and P70S6K activa tion. Insulin also does not inhibit lipolysis in chicken adipose tissue, glucagon, is the primary lipolytic hormone.

In the present study we simultaneously characterized the effects of a short term fast or neutralization of insulin action on adipose tissue of young, fed commercial broiler chickens. The goals of this study were Inhibitors,Modulators,Libraries two fold. First, we sought to iden tify pathways activated by feed restriction, reasoning that they may highlight potential strategies for control of fatness through either genetic selection or improved management practices. Simultaneously, we sought to understand the contribution of insulin, if any, into chicken adipose physi ology. No experimental model of diabetes exist in chicken, total pancreatectomies are not achievable, and alloxan and streptozotocin are inefficient at destroying pancreatic chicken beta cells. The two treatments were compared to distinguish potential insulin specific changes from those that could be mimicked by fasting through changes in nutrient availability. Both treatments were shown previously to elicit significant alterations in several plasma metabolic and endocrine parameters, in the studies reported herein, samples of abdominal adipose tis sue were issued from the same experiment.