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Title

The serotonin inhibition of high-voltage-activated calcium currents is relieved by action potential-like depolarizations in dissociated cholinergic nucleus basalis neurons of the guinea-pig

Authors
Williams, S.
Published in European Journal of Neuroscience. 1998, vol. 10, no. 10, p. 3291-3294
Abstract The aim of the present study was to investigate whether the voltage-dependent inhibition of calcium currents by serotonin 5-HT1A agonists can be alleviated (facilitated) by action potential-like depolarizations. In dissociated cholinergic basal forebrain neurons using whole-cell recordings, it is shown that a selective serotonin 5-HT1A agonist (8-OH-DPAT) predominantly blocks N-type HVA calcium current, although a minor reduction of P-type current was also observed. The inhibition may principally occur through Gi-Go subtypes of G-proteins because it was prevented by N-ethylmaleimide, a substance known to block specifically pertussis-sensitive G-proteins. The inhibitory effect of 8-OH-DPAT on calcium currents is voltage-dependent because it was alleviated by long-lasting depolarizing prepulses. Interestingly, the inhibition could also be reversed by prepulses made-up of action potential-like depolarizations that were given at a frequency of 200 Hz. This observation may have important implications during periods of high-frequency rhythmic bursts, a firing pattern that is prevalent in cholinergic basal forebrain neurons.
Keywords Action Potentials/physiologyAnimalsCalcium Channel Blockers/pharmacologyCalcium Channels/ physiologyCholinergic Fibers/drug effects/physiologyCulture TechniquesElectric StimulationGuinea PigsPeptides/pharmacologyReceptors, Serotonin/drug effectsSerotonin/ pharmacologySubstantia Innominata/cytology/drug effects/physiologyOmega-Conotoxin GVIA
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PMID: 9786223
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