Somatostatin in epithelial cells of intestinal mucosa is present primarily as somatostatin 28.
Region-specific antisera to [Tyr14]-SS28(1-14) were used to identify cells containing immunoreactivity to the SS28(1-14) fragment of somatostatin 28 (SS28) in gastric and intestinal mucosal epithelium and in pancreatic islets by immunoperoxidase staining. Radioimmunoassay with iodinated [Tyr14]-SS28(1-14) identified one antiserum (F4) to SS28(1-14) that cross-reacted equally with SS28(1-12), SS28(1-14) and SS28. Two other antisera (F3 and F8) to SS28(1-14) did not cross-react with SS28(1-12) and showed insignificant cross-reactivity to SS28. Immunostaining results showed that F4 stained the same cells that reacted with antiserum AS-10, which is specific for the cyclic tetradecapeptide somatostatin, SS28(15-28). Antisera F3, F4, and F8 all reacted with islet D cells and with somatostatin cells in the antral mucosa. However, only antiserum F4 detected immunoreactivity in mucosal epithelial cells; F3 and F8 did not bind to these cells. After sections of intestine were exposed to trypsin, however, epithelial cells containing immunoreactivity to SS28(1-14) were detected in intestinal mucosa with antisera F3 and F8. These results were obtained for duodenum, jejunum, ileum, and colon, but most of the epithelial cells with immunoreactivity to SS28(1-14) were in the duodenum. Both radioimmunoassay and immunostaining results suggest that F3 and F8 bind to a region of SS28(1-14) that is unavailable to antibodies in the intact SS28 molecule.(ABSTRACT TRUNCATED AT 250 WORDS)
D000818:Animals; D003429:Cross Reactions; D004847:Epithelial Cells; D004848:Epithelium / Q000032:analysis; D005753:Gastric Mucosa / Q000032:analysis / Q000166:cytology*; D007413:Intestinal Mucosa / Q000032:analysis* / Q000166:cytology*; D008297:Male; D009928:Organ Specificity; D010179:Pancreas / Q000032:analysis / Q000166:cytology; D011863:Radioimmunoassay; D051381:Rats; D011919:Rats, Inbred Strains; D013004:Somatostatin / Q000032:analysis*; D053561:Somatostatin-28
D013004:Somatostatin; D053561:Somatostatin-28