Distinct autoradiographic labelling of serotonin 5-HT2 receptors, alpha 1-adrenoceptors and histamine-H1 receptors and of tetrabenazine-displaceable ketanserin binding sites in rodent brain with [125I]7-amino-8-iodo-ketanserin.

[125I]7-Amino-8-iodo-ketanserin ([125I]AMIK) binding was assayed in rat and guinea-pig horizontal brain sections and was analysed by autoradiography. The use of selective displacers allowed the identification of four distinct receptors in rat and guinea-pig brain. In rats, 5-HT2 receptors were detected in cortical areas and in caudate putamen, alpha 1-adrenoceptors were found in cortical areas and several thalamic nuclei, tetrabenazine-displaceable ketanserin binding sites involved in the release of biogene amine metabolites occurred in caudate putamen, periaqueductal grey matter and septal nuclei. Histamine-H1 receptors could be identified in the guinea-pig cerebellum.