High affinity serotonin binding sites in human brain: a comparison of cerebral cortex and basal ganglia

The high-affinity binding of3H-serotonin and3H-DP-AT was studied in membrane preparations and tissue sections of cerebral cortex and basal ganglia of human brain. In tissue sections,3H-serotonin bound to sites present at high density in the cerebral cortex, hippocampus and basal ganglia.3HDPAT bound predominantly to the outer layers of the cerebral cortex and the hippocampus, no significant binding was observed in the basal ganglia. In cortical membranes3H-serotonin bound to a heterogeneous population of sites, one of which was similar to a binding site labelled by3H-DPAT (the putative 5HT-1A receptor).3H-serotonin binding to membranes prepared from the putamen displayed low affinity for DPAT, mesulergine and spiperone, RU 24969 was considerably less potent than serotonin itself. This3H-serotonin binding site does not have the properties of those sites described in rodent brain (5 HT-1 A, 5 HT-1 B, and 5 HT-1 C), and may represent a novel serotoninergic binding site.