Galanin message-associated peptide (GMAP)- and galanin-like immunoreactivities: overlapping and differential distributions in the rat.

Using the indirect immunofluorescence method the distribution of galanin message associated peptide (GMAP)- and galanin-like immunoreactivities (LI) was compared in brain, intestine and some endocrine tissues of rat. In general, neurons in the peripheral and central nervous system contained both immunoreactivities. However, in retina the cones were GMAP-positive but galanin-negative. A strong GMAP-LI was observed in the prolactin cells in the anterior lobe of the pituitary and in the insulin cells in the islets of Langerhans in the pancreas, whereas incubation with galanin antiserum resulted in staining of fewer cells (anterior pituitary) or a very weak fluorescence (pancreas). The results show that most neurons express both GMAP- and galanin-LI, but raise the possibility that in some systems there is a tissue specific, posttranslational differential processing of preprogalanin.