Dopamine-sensitive adenylate cyclase activity in the striatum in Parkinson's disease.

Dopamine (DA) sensitive adenylate cyclase activity was measured in homogenates of caudate nucleus and putamen from frozen brain of eight Parkinsonian patients and nine controls. In the control group, there was no difference in enzyme activity in respect to sex or age (21--77 years old). Caudate nucleus and putamen exhibited similar mean activity. In the Parkinsonian group, there was a significant decrease in both basal (by 50%) and DA stimulated (by 80%) activities compared with that of control group. This suggests that there may exist a functional disturbance in the postsynaptic (post-DA-nergic) region in the striatum of patients with Parkinson's disease; in addition, the decrease in basal as well as DA stimulated activity as measured in homogenates may not be the biochemical substrate for the hypothetical "denervation supersensitivity" expected to occur in Parkinson's disease.