NEURONS CONTAINING GASTRIN-RELEASING PEPTIDE-LIKE IMMUNOREACTIVITY INTHE HUMAN PANCREAS

Gastrin releasing peptide (GRP) is known to stimulate pancreatic enzym e and islet hormone secretion. In the present immunohistochemical stud y, the localization and distribution of GRP-like immunoreactivity were investigated in the human pancreas using two antisera with different specificities. GRP-like immunoreactivity (GRP-LI) was observed in nume rous nerve fibers diffusely distributed to the exocrine pancreas, but was not seen in intrapancreatic nerve cells of normal pancreatic speci mens examined. Nerve fibers and terminals with GRP-LI were found in ab undance around pancreatic acini and capillaries, with moderate density around ductules and in the walls of arterioles, and a few were seen i n islets. This distribution pattern was quite similar to that of vasoa ctive intestinal polypeptide (VIP)-LI nerve fibers. The study, using t he antibody elution method, strongly suggests the co-localization of G RP- and VIP-LIs within a part of VIP-containing nerve fibers. In the c hronic pancreatitis specimens, neurons with GRP-LI were frequently fou nd, and >90% of intrapancreatic nerve cells were VIP-immunoreactive. I mmunostainings for GRP and for VIP on serial adjacent sections of intr apancreatic ganglia from chronic pancreatitis specimens suggested the co-localization of the two immunoreactivities in >70% of intrapancreat ic neurons. The present findings may provide a morphological basis for neurotransmitter and/or neuromodulator roles of GRP in the human panc reas.