INTRACYTOPLASMIC INCLUSION-BODIES OF THE SUBSTANTIA-NIGRA IN MYOTONIC-DYSTROPHY - IMMUNOHISTOCHEMICAL OBSERVATIONS

We recently reported a significantly higher incidence of intracytoplas mic inclusion bodies (IIBs) of the substantia nigra in patients with m yotonic dystrophy (MyD) than in age-matched controls. The changes are, per se, not specific, since a small percentage of disease and normal controls also showed similar inclusions. To elucidate the pathological significance of the inclusion in MyD, we studied immunohistochemical characteristics of IIBs of the substantia nigra in eight patients with MyD. Many IIBs showed moderately intense immunoreactivity for ubiquit in, microtubule-associated protein (MAP) 1 and MAP 2. However, the IIB s did not react with any of the following: anti-neurofilament, protein antibodies (Abs) (68, 160 and 200 kDa), anti-neuron-specific enolase antibody (Ab), anti-tan Ab, anti-tubulin Abs (alpha and beta), anti-pa ired helical filament Ab, anti-actin Ab, anti-phosphorylated epitope o f neurofilaments Ab, anti-synaptophysin Ab, anti-myelin basic protein Ab, anti-actin Ab and anti-glial fibrillary acidic protein Ab. Our res ults suggest that IIBs of the substantia nigra in MyD are related to a n alteration of neuronal cytoskeleton metabolism affecting microtubula r proteins in conjunction with activation of ubiquitin proteolytic sys tems. (C) 1997 Elsevier Science B.V.