[The endocrine pancreas of birds]

The endocrine pancreas of birds contains 3 islet types and releases glucagon, insulin, somatostatin and avian pancreatic polypeptide (APP). Interactions between these hormones, and pancreatic hormone-plasma metabolite feedback mechanisms, are the main regulators of these secretions. In birds, total pancreatectomy induces a fatal hypoglycaemia associated with the disappearance of circulating glucagon, and an impaired glucose tolerance ascribed to the lack of insulin. Normoglycaemia can be restored in depancreatized birds by infusion of glucagon and insulin, provided that the G/I ratio is close to normal. Subtotal pancreatectomy provokes a diabetes characterized by a basal hyperglycaemia and an impaired glucose tolerance. However, while a transient diabetes is observed in most species, in the goose a permanent diabetes is obtained. These results point out the importance of the pancreas and especially of glucagon, in birds. This importance can also be detected in the protein metabolism, since total or subtotal pancreatectomy markedly increases the concentration of plasma aminoacids. As for lipid metabolism, in vivo and/or in vitro experiments have shown the sensitivity of the adipose tissue and liver cells to glucagon. Finally, contrary to the general opinion, insulin seems to be antilipolytic, as in mammals.