OBJECTIVETo understand the possible pathogenesis of sporadic multiple system atrophy (MSA).

METHODSThe immunoreactivity and ultrastructural features of glial cytoplasmic inclusions (GCIs) in 12 autopsy patients with MSA and 4 normal control groups were studied. All regional sections from each subject were evaluated with HE staining, Klüver-Barrera (KB), Holzer's, modified Gallyas-Braak's (GB) methods and immunohistochemical staining with alpha-synuclein and ubiquitin antibodies. Pontine white matter with abundant GCIs from case 1 was examined, using conventional electron microscopy, Gallyas-Braak's electron microscopy and immunoelectron microscopy.

RESULTSThe presence of GCIs as constantly demonstrated in all MSA patients. Strong alpha-synuclein immunoreactivity was observed in all of the ubiquitinated GCIs. However, the density of alpha-synuclein positive GCIs differed from case to case, and there was no relationship between the density of GCIs and age, sex, or MSA subtype. Ultrastructural features indicated that argyrophilic granule-associated filaments of about 25 nm in diameter were the predominant constituents of GCIs, and the anti alpha-synuclein antibody selectively labeled in these filaments. No GCIs and alpha-synuclein immunoreaction were found in control brain tissues.

CONCLUSIONSGCI was a pathognomonic change in sporadic MSA patients. Accumulation of alpha-synuclein in GCIs may occur during the early stags of MSA. Seletcive alpha-synuclein positive abnormal microtubules in GCIs therefore play an important role in the pathogenesis of MSA.