High-affinity 3H-serotonin binding to caudate: Inhibition by hallucinogens and serotoninergic drugs

Abstract

The specific binding of ³H-serotonin to calf caudate homogenate was studied. The dissociation constant was 2 nM and the number of specific sites was 14 fmoles/mg protein. Of many drugs tested, inhibition of specific ³H-serotonin binding occurred almost exclusively with serotonin agonists and antagonists. The concentrations for 50% inhibition of ³H-serotonin binding by serotonergic agonists follow: bufotenin, 6 nM; 5-methoxytryptamine, 12 nM; psilocin, 35 nM; dimethyltryptamine, 220 nM; and tryptamine, 270 nM. The concentrations for the antagonists were: LSD 9.5 nM; methysergide 16 nM and metergoline 25 nM.