5-Methoxy-N,N-dlmethyltryptamine (5-MeODMT) in concentratlons of 0.5-500 microM produced a significant lnhibltlon of [14C]5-hydroxytryptamine ([14C]5-HT) uptake in stnatal, luppocampal and hypothalamic crude synaptosomes from rat brain. Higher concentrations of 5-MeODMT (10 microM) also inhibited the uptake of [3H]dopamme ([3H]DA) and induced the release of [14C]5-HT and [3H]DA from preloaded synaptosomes. It appears that the 5-HT agonist properties of 5-MeODMT may involve reuptake inhibition in addition to the previously documented direct receptor stimulation 5-Methoxy-N,N-dimethyltryptarmne 5-Hydroxytryptamine Catecholammes Synaptosomal uptake