Neuropeptide Y is expressed in islet somatostatin cells of the hamster pancreas: a combined immunocytochemical and in situ hybridization study.

Neuropeptide Y (NPY) is known to occur in the autonomic nervous system, including the pancreatic islet innervation. We now present evidence that NPY is also expressed in endocrine islet cells in hamster pancreas. Thus, NPY-immunoreactivity and gene expression were detected in peripheral islet cells, using immunocytochemistry (ICC), in situ hybridization (ISH), and a combination of these techniques. Double immunostaining for NPY and somatostatin enabled localisation of NPY ot the vast majority of the somatostatin cells. However, a few somatostatin cells were devoid of NPY immunoreactivity and an occasional NPY-immunoreactive cell was devoid of somatostatin. ISH with an NPY mRNA specific probe, showed labelling of cells in the islet periphery. Furthermore, combined ISH for NPY mRNA and ICC for somatostatin showed autoradiographic labelling of somatostatin cells to a varying degree. Both somatostatin and NPY are inhibitors of insulin and/or glucagon secretion. Thus, in the islets these two peptides may be coreleased and cooperate in the regulation of islet hormone secretion. The role for NPY emanating from islet cells is probably paracrine rather than endocrine.