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

Background: We previously localized β3-adrenergic receptors immunohistochemically in human gastrointestinal smooth muscle and incidently found a population of human pancreatic islet cells and duodenal epithelial neuroendocrine cells that also expressed β3-adrenergic receptors. Aim: To identify the nature of the islet and duodenal cells that stained positive for β3-adrenergic receptors. Methods: Paraffin sections of human pancreas and duodenum and Chinese hamster ovary cells transfected with the human β3-adrenergic receptor were immuno-stained for β3-adrenergic receptors using an affinity-purified rabbit polyclonal antibody (anti-P12) raised against a 15 amino acid sequence (P12) of the human receptor. Immunohistochemical staining for the receptor was carried out in the presence and absence of P12 peptide and both somatostatin 14 and 18 peptides. β3-adrenergic receptor-stained sections were also double-immunostained with anti-insulin, -glucagon, -somatostatin and -pancreatic polypeptide antibodies. Results: A subpopulation of human pancreatic islet cells and duodenal epithelial cells expressed positive cytoplasmic β3-adrenergic receptor immunostaining. Using distribution and double-staining techniques, these cells were found to be somatostatin-positive D cells but not A or B cells. The positive staining of D cells with anti-P12 antibody was inhibited by prior incubation of the antibody with P12 peptide but not somatostatin-14 or -28 peptides. Pancreatic vascular smooth muscle and duodenal vascular and non-vascular smooth muscle also stained with anti-P12 antibody. Transfected Chinese hamster ovary cells showed positive membrane staining. Conclusion: We have identified a population of neuroendocrine cells in the human pancreas and duodenum that express β3-adrenergic receptors. These cells appear to be somatostatin D cells.