Widespread Distribution of Brain Dopamine Receptors Evidenced with [ ¹²⁵ I]Iodosulpride, a Highly Selective Ligand

Abstract

The new benzamide derivative [125I]iodosulpride is a highly sensitive and selective ligand for D-2 dopamine receptors and displays a very low nonspecific binding to membrane or autoradiographic sections. On autoradiographic images, D-2 receptors are present not only in well-established dopaminergic areas but also, in a discrete manner, in a number of catecholaminergic regions in which the dopaminergic innervation is still unknown, imprecise, or controversial, as in the sensorimotor cerebral cortex or cerebellum. This widespread distribution suggests larger physiological and pathophysiological roles for cerebral dopamine receptors than was previously thought.

Topography and collateralization of dopaminergic projections to primary motor cortex in rats

“…These observations are in good agreement with the rostro-caudal gradient known for the cortical distribution of dopamine concentrations (Kehr et al 1976), dopaminergic terminals (Descarries et al 1987) and DA-receptors (Martres et al 1985;Dawson et al 1986a;Dawson et al 1986b). …”

A Simple Method to Measure Baseline Occupancy of Neostriatal Dopamine D2 Receptors by Dopamine In Vivo in Healthy Subjects

“…As F rac cannot be measured directly, this is estimated from the count rate density (i.e., F rac plus nonspecific binding) in the cerebellum, a brain region almost devoid of D 2 R (Martres et al 1985). However, in vivo the endogenous DA competes with [ 11 C]raclopride for the D 2 R. This competition can be represented as:…”

Kinetic Analysis of Central [76Br]Bromolisuride Binding to Dopamine D2 Receptors Studied by PET

“…Because it has been demonstrated that the con centration of dopamine D2 receptors is negligible in cerebellar tissue (Kuhar et al, 1978;Martres et al, 1985), the cerebellum data have been fitted using the model shown in Fig. 1 without specific binding and thus including only four parameters.…”