The effect of myo-inositol on the insulin signaling cascade in broiler chicken

Abstract

Broiler chickens have been selected for high growth rate, meat yield and efficiency of feed conversion. These breeding goals influence the health and welfare of the animals and result in metabolic stress. This situation mobilizes carbohydrate reserve, glucose will be released and hyperglycaemia occurs. During long-lasting stress the energy balance can be improved by a higher cellular uptake of glucose. Therefore, hormonal background is a determining factor in stress situation. However, the results gained in different species cannot be extrapolated to broilers, because birds have greatly different insulin homeostasis compared to mammals, indicated by higher blood glucose levels and reduced insulin sensitivity. That is why it is not clear whether the already known glucose lowering effects of myo-inositol (MI) in mammals could be achieved in chickens as well to lower the high glucose level and increase the uptake of glucose for cellular energy gain. The aim of this study was to detect the effects of MI on insulin signaling cascade, particularly on phosphorylation of Akt, one of the most important cascade molecules in broiler chickens. As feed additives in order to increase blood MI concentrations, MI and phytic acid-degrading phytase were used and the amount of phosphorylated Akt was detected. For this experiment 48 broiler chickens belonging to six different feeding groups (control group, three phytase supplementations, two MI supplementations) were used. Blood samples were drawn, and thereafter liver and pectoral muscle samples were taken upon dissection on day 21. The MI and glucose concentrations of blood plasma were measured by specific photometric assays. The amount of phospho-Akt was detected by semiquantitative Western blotting; protein expression data were standardized to β-actin in the liver and to γ-actin in the skeletal muscle.