The antidepressant bupropion is a negative allosteric modulator of serotonin type 3A receptors.

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Pandhare A, Pappu AS, Wilms H, Blanton MP, Jansen M

The antidepressant bupropion is a negative allosteric modulator of serotonin type 3A receptors.

Neuropharmacology. 2017 Feb;113(Pt A):89-99. doi: 10.1016/j.neuropharm.2016.09.021. Epub 2016 Sep 24.

PubMed ID

27671323 [ View in PubMed

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Abstract

The FDA-approved antidepressant and smoking cessation drug bupropion is known to inhibit dopamine and norepinephrine reuptake transporters, as well as nicotinic acetylcholine receptors (nAChRs) which are cation-conducting members of the Cys-loop superfamily of ion channels, and more broadly pentameric ligand-gated ion channels (pLGICs). In the present study, we examined the ability of bupropion and its primary metabolite hydroxybupropion to block the function of cation-selective serotonin type 3A receptors (5-HT3ARs), and further characterized bupropion's pharmacological effects at these receptors. Mouse 5-HT3ARs were heterologously expressed in HEK-293 cells or Xenopus laevis oocytes for equilibrium binding studies. In addition, the latter expression system was utilized for functional studies by employing two-electrode voltage-clamp recordings. Both bupropion and hydroxybupropion inhibited serotonin-gated currents from 5-HT3ARs reversibly and dose-dependently with inhibitory potencies of 87 muM and 112 muM, respectively. Notably, the measured IC50 value for hydroxybupropion is within its therapeutically-relevant concentrations. The blockade by bupropion was largely non-competitive and non-use-dependent. Unlike its modulation at cation-selective pLGICs, bupropion displayed no significant inhibition of the function of anion-selective pLGICs. In summary, our results demonstrate allosteric blockade by bupropion of the 5-HT3AR. Importantly, given the possibility that bupropion's major active metabolite may achieve clinically relevant concentrations in the brain, our novel findings delineate a not yet identified pharmacological principle underlying its antidepressant effect.

DrugBank Data that Cites this Article

Drugs

Bupropion

Drug Targets

Drug	Target	Kind	Organism	Pharmacological Action	Actions
Bupropion	5-hydroxytryptamine receptor 3A	Protein	Humans	Unknown	Negative modulator	Details