Aging process affects a single class of dopamine receptors.

[3H]Spiroperidol and 3H-sulpiride specific binding have been used to assay for D1 and D2 dopaminergic recognition sites in striatal membranes of aged rats. While [3H]spiroperidol binding shows a decreased number of binding sites, no changes have been detected in 3H-sulpiride binding, which is a marker for D2 dopaminergic receptors. Data obtained with GTP and DA-dependent adenylyl cyclase activity confirm the hypothesis that aging selectively affects in rats those dopaminergic receptors coupled to the formation of cyclic AMP (D1).