Dopamine D-1 and D-2 receptors in Huntington's disease

Dopamine receptors were studied in post-mortem brains from control and Huntington's disease patients, using the specific binding of [3H]spiperone to dopamine D-2 receptors and [3H]piflutixol to dopamine D-1 receptors. Both [3H]spiperone binding and [3H]piflutixol binding were reduced by 45-50% in Huntington's disease putamen. The loss of [3H]spiperone and [3H]piflutixol binding sites correlated with decreased GABA concentrations observed in Huntington's disease putamen. A selective loss (48%) of [3H]piflutixol binding was observed in Huntington's disease substantia nigra pars reticulata, [3H]piflutixol binding was unchanged in substantia nigra pars compacta. No differences in [3H]spiperone binding were observed between the groups in either region of substantia nigra. The results are discussed in relation to the pathophysiology of Huntington's disease, and to the presence of distinct dopamine receptors in human brain.