Effects of iprindole on responses of single cortical and caudate neurones to monoamines and acetylcholine.

1 The technique of microelectrophoresis was used to study the effects of iprindole on single neurones in the cerebral cortex and caudate nucleus of the rat. 2 Iprindole, when applied for a brief period, did not affect the firing rate of the vast majority of neurones tested. 3 Both potentiation and antagonism of neuronal responses to noradrenaline, dopamine, and 5-hydroxytryptamine could be observed after a brief application of iprindole. Potentiation and antagonism often occurred after the same application of iprindole, antagonism always preceding potentiation. 4 Responses to acetylcholine were affected by iprindole similarly: both potentiation and antagonism of the responses could be observed. 5 Responses to glutamate were not affected by iprindole. 6 It is concluded that the potentiation of responses to monoamines by iprindole cannot be explained on the basis of uptake blockade; this potentiation may be due to the blockade of masked receptors on the post-synaptic cell. 7. It is suggested that the common pharmacological action of the tricyclic antidepressants may be the ability to block both monoamine and acetylcholine receptors in the brain.