ALTERATIONS IN [SPIPERONE-H-3 BINDING IN HUMAN CAUDATE-NUCLEUS, SUBSTANTIA NIGRA AND FRONTAL-CORTEX IN THE SHYDRAGER SYNDROME AND PARKINSONS-DISEASE

[3H]Spiperone binding was investigated in the caudate nucleus, substantia nigra (s.nigra) and frontal cortex of control subjects and of patients with Parkinson's disease and the Shy-Drager syndrome. Binding sites for [3H]spiperone were interpreted as dopamine receptors in caudate and s. nigra, and as 5-hydroxytryptamine (5-HT) receptors in frontal cortex. Scatchard analysis showed that the Bmax (maximal number of binding sites) in caudate was similar in the 3 groups, whereas in s. nigra the Bmax was reduced by approximately 60% in both Parkinson's disease and Shy-Drager syndrome. The dissociation constant (Kd) for [3H]spiperone binding in s. nigra was similar in the 3 groups. In caudate nucleus, the Kd was similar in control and Parkinson groups; however, there was a significant increase in the dissociation constant in the caudate nucleus from cases of Shy-Drager syndrome. No differences in binding characteristics were observed in the frontal cortex. These results are taken to reflect a loss of dopamine receptor sites in the s. nigra in both Parkinson's disease and Shy-Drager syndrome, and a reduced affinity of dopamine receptor sites in the caudate nucleus in Shy-Drager syndrome. © 1979.