Loss of rat striatal dopamine receptors with ageing is selective for D-2 but not D-1 sites: association with increased non-specific binding of the D-1 ligand [3H]piflutixol.

The effects of age on the binding of dopaminergic ligands to rat striatal membranes were studied. When compared with four month old animals, at 22 months there was a significant decrease in the density of specific binding sites for the D-2 ligand [3H]spiperone while their affinity was unaltered. However, the specific binding of [3H]piflutixol to D-1 sites was unaltered between these age groups. The non-specific binding of [3H]piflutixol was significantly increased in aged preparations. Age-related loss of striatal D-2 dopamine receptors does not extend to the D-1 type. Alterations in non-specific [3H]piflutixol binding may reflect other pathophysiological changes associated with senescence.