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5-HT3 receptors mediate serotonergic fast synaptic excitation of neocortical vasoactive intestinal peptide/cholecystokinin interneurons.

Abstract : Neocortical neurons expressing the serotonin 5-HT3 receptor (5-HT3R) were characterized in rat acute slices by using patch-clamp recordings combined with single-cell RT-PCR and histochemical labeling. The 5-HT3A receptor subunit was expressed selectively in a subset of GABAergic interneurons coexpressing cholecystokinin (CCK) and vasoactive intestinal peptide (VIP). The 5-HT3B subunit was never detected, indicating that 5-HT3Rs expressed by neocortical interneurons did not contain this subunit. In 5-HT3A-expressing VIP/CCK interneurons, serotonin induced fast membrane potential depolarizations by activating an inward current that was blocked by the selective 5-HT3R antagonist tropisetron. Furthermore, we observed close appositions between serotonergic fibers and the dendrites and somata of 5-HT3R-expressing neurons, suggestive of possible synaptic contacts. Indeed, in interneurons exhibiting rapid excitation by serotonin, local electrical stimulations evoked fast EPSCs of large amplitude that were blocked by tropisetron. Finally, 5-HT3R-expressing neurons were also excited by a nicotinic agonist, indicating that serotonergic and cholinergic fast synaptic transmission could converge onto VIP/CCK interneurons. Our results establish a clear correlation between the presence of the 5-HT3A receptor subunit in neocortical VIP/CCK GABAergic interneurons, its functional expression, and its synaptic activation by serotonergic afferent fibers from the brainstem raphe nuclei.
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https://hal.archives-ouvertes.fr/hal-02455009
Contributor : Alain Perignon Connect in order to contact the contributor
Submitted on : Saturday, January 25, 2020 - 10:00:19 AM
Last modification on : Wednesday, July 7, 2021 - 2:15:00 PM

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Isabelle Férézou, Bruno Cauli, Elisa Hill, Jean Rossier, Edith Hamel, et al.. 5-HT3 receptors mediate serotonergic fast synaptic excitation of neocortical vasoactive intestinal peptide/cholecystokinin interneurons.. Journal of Neuroscience, Society for Neuroscience, 2002, 22 (17), pp.7389-97. ⟨10.1523/JNEUROSCI.22-17-07389.2002⟩. ⟨hal-02455009⟩

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