A comparative immunohistochemical study on a galanin-like peptide in the neuroendocrine system of the alimentary canal of three species of siluriform catfishes

Abstract

Immunohistochemical examination of the galaninergic and the diffuse endocrine systems of the alimentary canal of three catfish species, Ameiurus melas, Silurus glanis and Clarias gariepinus showed the presence of galanin-like immunoreactive endocrine cells in the stomachs and the proximal intestines and a galanin-like immunoreactivity within the enteric intramural neurons. The three species differed notably in the relative abundance of galaninergic neurons of the digestive system. A galanin-like peptide was detected in a high number of nerve bundles and nerve fibres running through the exocrine parenchyma and the endocrine islets of the pancreas of all three species. It is conceivable that the galaninergic system in these species plays a role in regulating gut muscle activity, in modulating mucosal secretive and absorptive processes, and in controlling pancreatic hormone secretion.