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

The localization of glial cell line-derived neurotrophic factor (GDNF) fami ly receptor alpha-1 (GFR alpha-1) was investigated in rat brain by immunohi stochemistry using a polyclonal antibody against a specific sequence of the rat protein. For raising the antisera in rabbits, we synthesized the oligo peptide SDVFQQVEHISKGN that corresponds to residues 139 to 152 of rat GFR a lpha-1. On immunospot assay, 0.5 mu g/ml of an affinity-purified antibody w as capable of detecting 7.8 pmol of the rat GFR alpha-1 oligopeptides. When rat brain homogenates were examined by Western blots, the antibody reveale d two main bands with molecular weights of approximately 47 kDa and 53 kDa, corresponding to the known sizes of GFR alpha-1. Immunohistochemistry in r at brain demonstrated that GFR alpha-1-like immunoreactivity was present in neurons but not in glial cells. The localization of GFR alpha-1-like immun oreactivity was largely consistent with that of the corresponding GFR alpha -1 mRNA. Positive neurons were distributed widely in various brain regions, but were particularly abundant in such regions as the olfactory bulb, diag onal band, substantia innominata, zona incerta, substantia nigra, cerebella r cortex, nuclei of the cranial nerves including auditory system and spinal motoneurons. The present study showed that GFR alpha-1 in the normal centr al nervous system is expressed preferentially in certain multiple neuronal systems that include cholinergic system as well as dopaminergic system and motor neurons. As GFR alpha-1 protein was found in numerous brain structure s, GDNF family ligands may have therapeutic application not only in degener ative diseases affecting in specific nervous systems, such as Parkinson's d isease, amyotrophic lateral sclerosis and multiple system atrophy, but in d iffusely damaging diseases like cerebrovascular diseases. (C) 2000 Elsevier Science B.V. All rights reserved.