Submitted to: Experimental Biology
Publication Type: Abstract Only
Publication Acceptance Date: March 6, 2006
Publication Date: March 7, 2006
Citation: Sweazea, K.L., McMurtry, J.P., Braun, E.J. 2006. Inhibition of fatty acid lipolysis does not affect insulin sensitivity to glucose uptake in the mourning dove [abstract]. FASEB Journal. 20:A1465.
Birds have much higher plasma glucose and fatty acid levels in comparison to mammals. In addition, they are resistant to the blood glucose lowering effects of insulin. Recent studies have demonstrated that decreasing fatty acid utilization alleviates insulin resistance in mammals, thereby decreasing glucose levels. This has yet to be examined in birds. In the present study, the levels of glucose and ketone bodies, an indicator of fatty acid utilization, were measured after the administration of insulin, acipimox (an agent used to decrease fatty acid utilization), or insulin and acipimox. Insulin significantly decreased whole blood glucose levels 19%, but had no effect on ketone body concentrations. In contrast, acipimox decreased whole blood ketone body levels 41%, but had no effect on whole blood glucose. In addition to changes in blood composition, levels of glucose uptake by various tissues were measured after the individual and combined administration of insulin and acipimox. Under basal conditions the uptake of glucose, expressed as nM uptake per mg tissue, appeared to be greatest in the kidney (15.4 ± 3.2) followed by the brain (2.4-2.5) and skeletal muscle (0-0.36) with negligible uptake by heart, liver and adipose tissues. Acipimox significantly decreased glucose uptake by brain (58% in cortex; 55% in cerebellum) and there was a tendency for acipimox to decrease glucose uptake by the kidney, pectoralis and latissimus dorsi, but these were not significant. No effect of acipimox was observed in other tissues. In summary, the acute inhibition of fatty acid lipolysis had no effect on glucose uptake in the presence or absence of insulin. This suggests that free fatty acids alone may not be contributing to insulin resistance in birds.