Avian endocrine pancreatic performance and its regulation of glucose homeostasis has received little study in Falconiformes or Strigiformes but has been studied quite extensively in species of Galliformes and to a lesser degree in Anseriformes. This review consolidates current thoughts concerning the role of the raptor pancreas in glucose homeostasis and the conclusions derived were compared mainly to those of the most thoroughly studied representive of all avian vertebrates, the domestic chicken. Fasting or basal levels of blood insulin varied widely but mean values were within the ranges which are found in mammalian vertebrates and possibly lower than the means of some values which were reported for chickens. Basal insulin levels never appeared to be affected by short or long-term fasting itself or myriad forms of stress. Basal glucose levels during fasting or stressful circumstances were not significantly different from those of comparably fasted chickens. Fasting glucagons levels, although varying widely, were consistently lower than those of chickens. Insulin/glucagon ratios in fgasting and/or stressful states were lower than previously described in chickens while existing under similar circumstances. Studies of glucose tolerance show that normal kestrels, after having challenged with oral glucose, appear to absorb and utilize glucose at faster rates than chickens and these data indirectly suggest that β-cells of the raptor pancreas may be very responsive to glucose stimulation. Post-feeding hypoglycemia, an injury-induced phenomenon, its relationship to the central nervous system and possible mechanisms of induction are discussed.
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