Recent advances in pancreatic hormone research.

Abstract

Summary The pancreas secretes 4 major polypeptide hormones: insulin from the beta cells; pancreatic glucagon from the alpha cells; somatostatin from the D cells in the islets of Langerhans, and pancreatic polypeptide (PP) from the PP cells which are spread more diffusely through pancreatic exocrine and endocrine tissue. Some or all of these 4 hormones may also have paracrine effects; this means that the peptide is secreted locally and has metabolic effects on neighbouring cells. Gastrin is synthesized in G cells in the foetal pancreas, but these cells disappear postnatally. Certain other polypeptides such as vasoactive intestinal polypeptide (VIP) have also been demonstrated in human pancreas, but appear predominantly localized to nerves; these substances, which were initially classified as ‘gut hormones’, are now thought to be neurotransmitters or neuromodulators of the non-adrenergic, non-cholinergic branch of the autonomic nervous system. In view of the multiple modes of actions of these peptides, the descriptive term ‘regulatory peptides’ is now often used. Basic information about the peptides to be discussed is listed in Table 1, but it should be emphasized that many of them exist in multiple molecular forms. The purpose of this review is to discuss some primarily non-diabetic aspects of the physiology and pathophysiology of pancreatic polypeptides which have recently received attention.