CANINE GALANIN - SEQUENCE, EXPRESSION AND PANCREATIC EFFECTS

To determine if dog galanin is a potent inhibitor of dog insulin secre tion we determined its primary structure from its cloned cDNA, evaluat ed its expression in celiac ganglia and determined its effect on islet hormone secretion. The predicted amino acid sequence differs from the other known species of galanin by three to six amino acids in the C-t erminal half of the molecule. In situ hybridization revealed the prese nce of dog progalanin mRNA in every neuronal cell body in the dog celi ac ganglion. The predicted dog galanin peptide was synthesized and inf used i.v. at 0.25, 2.5, 25 or 250 pmol/kg/min. It potently inhibited i nsulin secretion, less potently inhibited pancreatic somatostatin rele ase and stimulated glucagon secretion, similar to the effects of porci ne galanin in the dog. In summary, dog galanin is expressed in the neu ronal cell bodies that innervate the pancreas and the sequence of the dog galanin preserves the potent insulin inhibitory part of the galani n molecule. These data support the hypothesis that galanin is a sympat hetic neurotransmitter in dog pancreas.