IMMUNOHISTOCHEMICAL LOCALIZATION OF SOMATOSTATIN RECEPTOR SST2A IN THE RAT PANCREAS

Somatostatin (SRIF) acts on specific membrane: receptors to inhibit ex ocrine and endocrine pancreatic functions. Five SRIF receptor genes ha ve been cloned, producing six receptor proteins (sst-s). We used a rec ently developed antibody to localize the sst2A splice variant in the r at pancreas. Western blots identified the sst2A. receptor as an 90 kDa glycosylated protein in pancreatic tissue. In tyramide-amplified immu nostainings all acinar cells, and the glucagon and pancreatic polypept ide immunoreactive cells (A and PPI respectively) were intensely label ed for sst2A, while no signal was detected in SRIF producing (D) cells . A very few insulin immunoreactive (B) cells were also labeled for ss t2A, but the signal in these cells was lower than in exocrine, A or PP cells. Absorption of the sst2A antibody with the receptor peptide abo lished specific staining in both immunoblots and tissue sections (nega tive control). These studies are the first to localize any SRIF recept or subtype in the rat pancreas. The specific localization of sst2A rec eptor in acinar, A and PP cells if confirmed in humans, would suggest that subtype specific analogs will be useful for the therapeutic relat ion of exocrine and/or endocrine pancreatic secretion.