The in vivo and in vitro occupation of [ 3H]-spiperone binding sites in the frontal cortex and striatum by putative 5-hydroxytryptamine antagonists

The in vitro and in vivo occupation of [ 3H]-spiperone binding sites in, respectively, rat and mouse frontal cortex and striatum by several putative 5-hydroxytryptamine (5-HT) antagonists and members of other psychotropic drug classes has been assessed. The results indicate a binding site heterogeneity consistent with the labelling of both 5-HT and dopamine (DA) receptors by [ 3H]-spiperone both in vitro and in vivo. Drug interactions at both these sites may have important pharmacological implications. Some antidepressant agents selectively occupy frontal cortical binding sites and this may be associated with the anxiolytic properties of these agents. Whereas the cataleptogenic neuroleptic drugs are more active at striatal dopaminergic sites, the novel non-cataleptogenic agent, clozapine, shows preferential activity at the frontal cortical serotonergic sites.