Beta‐adrenergic receptor subtypes in the basal ganglia of patients with Huntington's chorea and Parkinson's disease

The density of [¹²⁵I]iodo‐cyanopindolol binding to beta‐1 and beta‐2 adrenergic receptors was studied in post mortem basal ganglia samples of Huntington's chorea and Parkinson's disease patients using autoradiography. Whereas no significant changes were observed in sections from Parkinson's and Huntington's chorea grade 2 patients, a nearly complete loss of beta‐1 binding sites was observed in the basal ganglia of Huntington patients at later stages of the disease. The concentration of beta‐2 receptors was increased by a factor 2 in the posterior putamen of all choreic cases. These results are consistent with the view that beta‐1 receptors are predominantly located on a subpopulation of neurons which degenerate at late stages of Huntington's chorea, while beta‐2 receptors are present mainly on glial elements.