[3H]spiperone binding, dopamine and HVA concentrations in Parkinson's disease and supranuclear palsy

The density of D2-type dopamine receptors, measured by the binding of [3H]spiperone was normal in the substantia nigra, caudate nucleus and nucleus accumbens of Parkinsonian subjects and above control levels in the putamen, in spite of massive lesions of the dopaminergic neurons. Dopamine levels were reduced in the putamen, caudate nucleus, and nucleus accumbens by 97, 85 and 68%, respectively and by 78 and 93% in the pars compacta and pars reticulata of the substantia nigra. HVA levels were much less affected suggesting that increased activity of the remaining dopaminergic neurons compensated to some extent for the lesions. Neuroleptic treatment and the presence of dementia in the Parkinsonian subjects affected [3H]spiperone binding and dopamine concentrations. Dopamine and HVA levels in the striatum of subjects with supranuclear palsy indicate that the nigrostriatal system was lesioned to the same degree in this disease as in idiopathic Parkinsonism, but spiperone binding was reduced by half in all the structures studies.