The potentiation of cortical neurone responses to noradrenaline by beta-phenylethylamine: effects of lesions of the locus coeruleus.

beta-Phenylethylamine (PE) potentiates single cortical neurone responses to noradrenaline (NA). The hypothesis that this is due to an action on the noradrenergic presynaptic terminal was tested. Extracellular recordings of the responses of single cortical neurones to iontophoretically applied NA and PE were made in rats with unilateral electrolytic lesions of the locus coeruleus. Ipsilateral lesions blocked responses to PE but did not affect the ability of PE to enhance responses to NA. Contralateral lesions had no effect on either the responses to PE or the enhancement of responses to NA. It is concluded that the PE-induced potentiation of responses to NA is not due to a presynaptic action of PE.