Immunohistochemical localization of glial cell line-derived neurotrophic factor family receptor α-1 in the rat brain: confirmation of expression in various neuronal systems

Abstract The localization of glial cell line-derived neurotrophic factor (GDNF) family receptor α-1 (GFRα-1) was investigated in rat brain by immunohistochemistry using a polyclonal antibody against a specific sequence of the rat protein. For raising the antisera in rabbits, we synthesized the oligopeptide SDVFQQVEHISKGN that corresponds to residues 139 to 152 of rat GFRα-1. On immunospot assay, 0.5 μg/ml of an affinity-purified antibody was capable of detecting 7.8 pmol of the rat GFRα-1 oligopeptides. When rat brain homogenates were examined by Western blots, the antibody revealed two main bands with molecular weights of approximately 47 kDa and 53 kDa, corresponding to the known sizes of GFRα-1. Immunohistochemistry in rat brain demonstrated that GFRα-1-like immunoreactivity was present in neurons but not in glial cells. The localization of GFRα-1-like immunoreactivity was largely consistent with that of the corresponding GFRα-1 mRNA. Positive neurons were distributed widely in various brain regions, but were particularly abundant in such regions as the olfactory bulb, diagonal band, substantia innominata, zona incerta, substantia nigra, cerebellar cortex, nuclei of the cranial nerves including auditory system and spinal motoneurons. The present study showed that GFRα-1 in the normal central nervous system is expressed preferentially in certain multiple neuronal systems that include cholinergic system as well as dopaminergic system and motor neurons. As GFRα-1 protein was found in numerous brain structures, GDNF family ligands may have therapeutic application not only in degenerative diseases affecting in specific nervous systems, such as Parkinson's disease, amyotrophic lateral sclerosis and multiple system atrophy, but in diffusely damaging diseases like cerebrovascular diseases.