α-Synuclein is a major constituent of glial cytoplasmic inclusions (GCIs), which are pathognomic for multiple system atrophy (MSA). We have previously demonstrated that in normal human brain, α-synuclein mRNA has a restricted pattern of neuronal expression and no apparent glial expression. The current study used double-label in situ hybridization to determine if α-synuclein mRNA is expressed by oligodendroglia of MSA cases. Analysis of MSA brain tissue revealed depletion of regional signal for this transcript in many brain areas due to extensive neurodegeneration. Cellular analysis of oligodendroglia in crus cerebri, a GCI-rich region ventral to substantia nigra, revealed an absence of α-synuclein mRNA signal in control and MSA cases. However, an abundance of this transcript was detected in melanin-containing neurons of substantia nigra. Therefore, oligodendroglia do not express α-synuclein mRNA in control and MSA cases suggesting that involvement of α-synuclein in GCI pathology of MSA is due to its ectopic presence in oligodendroglia. © Springer-Verlag 2005.
