Abstract
Extracellular recording and iontophoresis techniques were used to study the interactions of the trace amine, pβtyramine (pβTA) with putative neurotransmitters on single neurones in the cerebral cortex and caudate nucleus of the rat. pβTA, when applied with weak iontophoretic currents which did not result in any change in neuronal firing rate, caused a pronounced potentiation of depressant responses to iontophoretically applied dopamine (DA). Depressant responses of cortical neurones to noradrenaline were also markedly potentiated by weak background applications of pβTA. This potentiating action of pβTA was related to the amount of the trace amine applied and was apparently specific for catecholamines, since depressant responses to 5βhydroxytryptamine and Ξ³βaminobutyric acid were unaffected. Excitatory responses to iontophoretically applied glutamate were also unaltered by weak applications of pβTA. Excitatory responses of most neurones to acetylcholine (ACh) were also unaffected by pβTA in the cortex and caudate nucleus. However, responses to ACh of a small number of cells in both brain areas were reduced in size during weak applications of pβTA. It is suggested that pβTA may act as a modulator of neurotransmission, particularly that mediated by DA in the central nervous system.