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bioRxiv · 10.1101/2022.12.09.519723

5-HT1A and 5-HT2B receptor interaction and co-clustering regulates serotonergic neuron excitability

Benhadda, A.·Delhaye, C.·Moutkine, I.·Marques, X.·Russeau, M.·Le Magueresse, C.·Roumier, A.·Levi, S.·Maroteaux, L.
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Abstract

Many psychiatric diseases including depression, schizophrenia and anxiety have been associated with serotonin (5-HT) neuron dysfunction. Pacemaker-like firing of raphe 5-HT neurons was proposed to be under unique 5-HT1A receptor-mediated autoinhibition. We previously showed that 5-HT2B receptors were expressed by 5-HT neurons together with 5-HT1A receptors. However, functional consequences on 5-HT neurons of putative interaction between these receptors are unknown. Using co-immunoprecipitation, BRET, confocal and super-resolution microscopy in hippocampal and 5-HT neurons, we present converging evidence that 5-HT1A and 5-HT2B receptors can form heterodimers and co-cluster at the surface of dendrites. 5-HT2B receptor clusters were redistributed upon 5-HT1A receptor expression supporting functional interactions between the two receptors. Furthermore, 5-HT2B receptor expression prevented agonist-induced internalization of 5-HT1A receptors, whereas 5-HT1A receptors mimicked the clustering effect of 5-HT2B receptor stimulation on its surface expression. The functional impact of this interaction in-vivo was assessed by recording 5-HT neuron excitability from mice lacking 5-HT2B receptors in 5-HT neurons. Upon 5-HT1A receptor stimulation, the firing activity of 5-HT neurons was increased in the absence of 5-HT2B receptors and decreased in their presence through regulation of SK channels, thus demonstrating functional output of this interaction in controlling 5-HT neuron firing activity.

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Benhadda, A., Delhaye, C., Moutkine, I., Marques, X., Russeau, M., Le Magueresse, C., Roumier, A., Levi, S., Maroteaux, L.. 2022-12-09. 5-HT1A and 5-HT2B receptor interaction and co-clustering regulates serotonergic neuron excitability. https://doi.org/10.1101/2022.12.09.519723

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