Long-lasting facilitation by dehydroevodiamine. HClof synaptic responses evoked in the CA1 region of rat hippocampal slices.

We tested the effects of dehydroevodiamine.Cl (DHED) on field excitatory postsynaptic potentials (fEPSPs) evoked by the electrical stimulation of Schaffer collaterals-commissural fibres in the CA1 region of rat hippocampal slices. Bath applications of 10 microM DHED for 20 or 40 min induced long-lasting facilitation of fEPSPs, which outlasted the presence of DHED. A 10 min treatment with a higher concentration (100 microM) also induced long-lasting facilitation. The long-lasting facilitation was blocked either by 10 microM atropine, the muscarinic receptor antagonist, or by 50 microM D-2-amino-5-phosphonopentanoic acid (D-AP5), an NMDA receptor antagonist. These results show that DHED produces long-lasting facilitation of synaptic transmission, and that this facilitation depends upon the activation of both the muscarinic and NMDA receptors.