Immunohistochemical localization of different forms of somatostatin in the gastrointestinal tract of the calf

The presence of two peptides that belong to the somatostatin family has been investigated in the calf gut. Somatostatin-14-like and Somatostatin-28-like peptides have been localized by a light microscopic immunohistochemical method. The method employed antibodies linked to colloidal gold particles that were revealed by a silver-enhancement step. Somatostatin-14-like peptide was only present in mucosal endocrine cells, which were detectable along the entire gut with the exceptions of the abomasal gastric proper glands and caecum. The cells were most abundant in cardiac and pyloric glands. Langerhans' islets also contained this type of endocrine cell. Somatostatin-28-like -immunoreactive endocrine cells were more abundant than the former cell type. They were present in the gastric proper glands and caecum where Somatostatin-14-like -immunoreactive cells were absent. They were as numerous as the former type of cell in the endocrine pancreas. The Somatostatin-28-like peptide was also detectable in the intramural nervous components of the abomasum and the intestine, in both perikarya and terminals. Our results show a possible heterogeneity of an endocrine cell type, which synthesizes and secretes somatostatin peptides. Our results also support the hypothesis that somatostatin-14 and somatostatin-28 peptides may have distinct functional roles, particularly in different species.