Beta(beta)(3)-adrenergic receptors in human pancreatic islet and duodenal somatostatin neuroendocrine cells

Background: We previously localized beta(3)-adrenergic receptors immunohist ochemically in human gastrointestinal smooth muscle and incidently found a population of human pancreatic islet cells and duodenal epithelial neuroend ocrine cells that also expressed beta(3)-adrenergic receptors. Aim: To identify the nature of the islet and duodenal cells that stained po sitive for beta(3)-adrenergic receptors. Methods: Paraffin sections of human pancreas and duodenum and Chinese hamst er ovary cells transfected with the human beta(3)-adrenergic receptor were immuno-stained for beta(3)-adrenergic receptors using an affinity-purified rabbit polyclonal antibody (anti-P12) raised against a 15 amino acid sequen ce (P12) of the human receptor. Immunohistochemical staining for the recept or was carried out in the presence and absence of P12 peptide and both soma tostatin 14 and 18 peptides. beta(3)-adrenergic receptor-stained sections w ere also double-immunostained with anti-insulin, -glucagon, -somatostatin a nd -pancreatic polypeptide antibodies. Results: A subpopulation of human pancreatic islet cells and duodenal epith elial cells expressed positive cytoplasmic beta(3)-adrenergic receptor immu nostaining. Using distribution and double-staining techniques, these cells were found to be somatostatin-positive D cells but not A or B cells. The po sitive staining of D cells with anti-P12 antibody was inhibited by prior in cubation of the antibody with P12 peptide but not somatostatin-14 or -28 pe ptides. Pancreatic vascular smooth muscle and duodenal vascular and non-vas cular smooth muscle also stained with anti-P12 antibody. Transfected Chines e hamster ovary cells showed positive membrane staining. Conclusion: We have identified a population of neuroendocrine cells in the human pancreas and duodenum that express beta(3)-adrenergic receptors. Thes e cells appear to be somatostatin D cells.