Somatostatin-14 and somatostatin-28 in chicken pancreatic islet D-cells

Somatostatin (SST)-14 and mammalian (m) SST-28[1-14] immunoreactivities of chicken pancreatic islets were investigated by using light microscopic immunohistochemistry. Chicken D-cells in both A- and B-islets showed immunoreactivity to SST-14, but not to mSST-28[1-14]. The acid-extract from both splenic and ventral lobes of pancreas was fractionated by reverse-phase high-performance liquid chromatography, and the SST-like immunoreactivity was measured in the radioimmunoassay using anti-SST-14 serum. In both lobes, the SST-like immunoreactivity was detected in the fraction which corresponded to that of SST-14 standard, but was not found in that of mSST-28 standard. Immunohistochemically, pancreatic endocrine D-cells of 1 amphibian, 4 reptiles and 12 birds showed the same immunostaining property as chicken D-cells. By contrast, both SST-14- and mSST-28[1-14]-immunoreactive D-cells were observed in the pancreatic islets of 16 mammals. From these results, we concluded that chicken islet D-cells contain only SST-14-like peptide, but not SST-28-like peptide, and that this phenomenon may be common to the avian species.