＜Symposium III＞Pathology of neuro-glial α-synucleinopathy (Lewy body disease and multiple system atrophy)

α-Synucleinopathies comprise a group of neurodegenerative disorders that share α-synuclein （αS） accumulation in selected vulnerable neurons and glia, i.e. Parkinson’s disease （PD）, dementia with Lewy bodies and multiple system atrophy（ MSA）. The histological hallmark of PD is neuronal αS aggregates called Lewy bodies（ LBs）. LB formation has been considered to be a marker for neuronal degeneration, because neuronal loss is found in the predilection sites for LBs. However, recent studies have suggested that oligomers and protofi brils of αS are cytotoxic, and that LBs may represent a cytoprotective mechanism in PD. The histological hallmark of MSA is αS aggregates in the oligodendrocytes referred to as glial cytoplasmic inclusions（ GCIs）. αS inclusions are also found in the neuronal somata, axons and nucleus. At present, two degenerative processes have been considered in this disease; one is due to the widespread occurrence of GCIs associated with oligodendroglia-myelin degeneration, and the other is due to the aggregation of αS in neurons in several brain regions. These two processes might synergistically cause neuronal depletion in MSA