Drug inhibition indicates a single-site model of the 5-HT uptake site/antidepressant binding site in rat and human brain

Drug inhibition against [³H]paroxetine binding to rat cortex and human putamen was investigated in saturation experiments. The addition of 5-HT, imipramine, citalopram and clomipramine all produced changes in apparent binding affinity (K_d) without changes in the number of binding sites (B_max). These data suggest that there is no heterogeneity of specific [³H]paroxetine binding, supporting a single site model of the 5-HT uptake site and antidepressant binding site.