Pancreatic galanin: molecular forms and anatomical locations

Galanin-like immunoreactivity (GalLI) was found to be present in extracts taken from human, canine, and porcine pancreata. The dominant gel filtration peak in each species co-elutes with standard synthetic porcine galanin (Gal), but an apparently smaller molecular weight Gal form was present in human pancreas and intestine and in dog intestine. Reverse-phase HPLC demonstrated identity of porcine pancreatic Gal immunoreactivity with synthetic intestinal Gal. Heterogeneity was seen on reverse-phase HPLC: Human pancreas and intestine had three peaks of immunoreactivity; the retention times were identical between the pancreas and intestinal extracts; and human Gal elutes at an earlier retention time than porcine Gal. Similarly, dog pancreatic GalLI eluted earlier than porcine Gal on reverse-phase HPLC. Immunohistochemical studies revealed the presence of specific staining for GalLI in varicose nerve fibers in the pancreas of the three species. In the dog pancreas an association between Gal-containing nerve fibers and islet cells was readily demonstrable. This was not the case with pig or human pancreas. We conclude that pancreatic Gal is present in the pancreas of the three species and that molecular heterogeneity is similar between intestinal and pancreatic forms. In the dog, a distinct anatomical relationship is demonstrable between Gal-containing nerves and islet cells.