A nicotinic-dopaminergic hybrid probe enhances D2-like autoreceptor-mediated inhibition of dopamine release - 20/09/26
, Cecilia Gotti c, ⁎ 
Abstract |
β2-containing nicotinic acetylcholine receptors (nAChRs) and dopamine D 2 receptors (D 2 Rs) cooperate to shape striatal dopamine (DA) output, yet the mechanisms by which nicotinic-dopaminergic crosstalk influences D 2 -like autoreceptor-mediated inhibition of DA release remain unclear. Here we use NiCh8 , a covalently linked nicotinic–dopaminergic hybrid, as a molecular probe to test whether single-molecule co-engagement can enhance D 2 -like autoreceptor-mediated inhibition of DA release. NiCh8 binds native α4β2* and α6β2* nAChRs as well as D 2 Rs, and behaves as a very low-efficacy partial agonist with antagonistic activity at α4β2 nAChRs. In equilibrium slice/synaptosome assays, NiCh8 elicits a modest dihydro-β-erythroidine-sensitive [³H]DA release that is absent in α4/α6 double-knockout (KO) synaptosomes. Strikingly, in superfused striatal synaptosomes NiCh8 potently suppresses basal and nicotine (NIC)-evoked DA outflow at nanomolar concentrations; this inhibition is preserved in β2-KO preparations, abolished by sulpiride, and is not reproduced by the parent pharmacophores ( NONI and PAMC ) alone or in combination. Structure-guided modeling supports a plausible bitopic binding mode at D 2 R, in which the dopaminergic fragment is predicted to engage the orthosteric site while the nicotinic fragment may contact a secondary binding region, providing a working structural rationale for the observed inhibitory phenotype. Together, these data identify NiCh8 as a hybrid probe that functionally enhances sulpiride-sensitive D 2 -like autoreceptor-mediated inhibition of DA release and provides a basis for future studies testing the role of D 2 R secondary-pocket engagement.
Le texte complet de cet article est disponible en PDF.Graphical Abstract |
Highlights |
• | NiCh8 incorporates a nicotinic and a dopaminergic pharmacophore connected by a flexible spacer |
• | This ligand behaves as a very low-efficacy partial agonist with antagonist activity at α4β2 nAChRs |
• | The effects of NiCh8 on [ 3 H]DA release have been assessed using equilibrium and superfusion protocols |
• | It inhibits basal and nicotine-evoked [ 3 H]DA outflow in a sulpiride-sensitive and a β2-independent manner |
• | Molecular modeling analysis supports a bitopic binding mode at dopamine D 2 receptors |
Keywords : Nicotinic acetylcholine receptors, Dopamine D 2 receptor , Dopamine release, Striatal synaptosomes, Bifunctional hybrid ligand, Bitopic ligand, Secondary binding pocket, Nicotine addiction
Plan
Vol 203
Article 119867- octobre 2026 Retour au numéroBienvenue sur EM-consulte, la référence des professionnels de santé.
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