Autoradiographic localization of dopamine receptors in the spinal cord of the rat using [3H]-N-propylnorapomorphine.

Dopamine receptors were localized autoradiographically in the rat spinal cord after in vitro labelling using 3H-N-propylnorapomorphine (NPA). The highest densities of 3H-NPA binding sites were found in the substantia gelatinosa and in a zone of the grey matter immediately ventral to the dorsal corticospinal tract. Other areas of the grey matter presented only moderate or low receptor densities while no 3H-NPA binding sites could be found in the white matter. The localization of 3H-NPA binding sites is compatible with a role for spinal cord dopamine in the processing of sensory information.