TrkA and TrkB neurotrophin receptor immunoreactivity in the teleost (Scorpaena porcus) endocrine pancreas

Mammalian-like and specific neurotrophins, as well as their cognate tyrosin e kinase Trk-like receptors have been identified in teleosts. They are main ly distributed in neuronal tissues, but evidence suggests that some non-neu ronal tissues also express Trks. In this study we used immunohistochemistry to investigate the occurrence and cell distribution of Trks in the pancrea s of teleosts (Scorpaena porcus). Immunoreactivity for TrkA and TrkB, but n ot for TrkC receptors, was found in the scorpionfish pancreas. TrkA-like po sitive cells were exclusively observed within pancreatic islets, among insu lin- and glucagon-containing cells, but apparently did not colocalize with these hormones. TrkB immunostaining was found in islet cells, presumably co localized with glucagon, as well as in some cells of the exocrine portion. These data provide a morphological basis for a role of the TrkA and TrkB li gands in the endocrine pancreas of teleosts. Anat Rec 263: 113-117, 2001. ( C) 2001 Wiley-Liss, Inc.