Noradrenaline Decreases Transmission of NMDA‐ and Non‐NMDA‐receptor Mediated Monosynaptic EPSPs in Rat Prefrontal Neurons In Vitro

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Abstract
The effects of noradrenaline on pyramidal cells of layer V of the prefrontal cortex were examined in rat brain slices in vitro. Bath administration of noradrenaline (10 μM) reduced synaptic transmission of afferent inputs from layer 1. The decrease affected all the components of the evoked response and particularly the monosynaptic excitatory postsynaptic potential (EPSP) as evidenced by a reduction of its initial rising slope (mean slope: 71 ± 11% of its control). Pharmacological dissociation of the NMDA- and non-NMDA-receptor components of the EPSP showed that noradrenaline reduced both (mean EPSP slopes were 71 ± 8% and 73 ± 10% of their control, respectively). Alpha1-, but not α-2- or β-adrenoceptor antagonists prevented the noradrenaline-induced decrease in synaptic efficacy. However, the effect of noradrenaline was not reproduced by α1-adrenoceptor agonists. Lastly, noradrenaline acting through β-adrenoceptors reduced the slow hyperpolarization that follows a train of action potentials.