Presynaptic P2X1-3 and α3-containing nicotinic receptors assemble into functionally interacting ion channels in the rat hippocampus. (June 2016)

• Record Type: Journal Article
• Authors: Rodrigues, Ricardo J.; Almeida, Teresa; Díaz-Hernández, Miguel; Marques, Joana M.; Franco, Rafael; Solsona, Carles; Miras-Portugal, María Teresa; Ciruela, Francisco; Cunha, Rodrigo A.
• Is Part Of: Neuropharmacology. Volume 105(2016)
• Page Start: 241
• Page End: 257
• Publication Date: 2016-06
• Subjects: P2X receptors -- Nicotinic receptors -- Hippocampus -- Noradrenaline -- Presynaptic -- Neuromodulation; nAChR nicotinic acetylcholine receptor -- P2R P2 receptor -- P2XR P2X receptor -- DβH dopamine-β-hydroxilase -- DHβE dihydro-β-erythroidine -- MLA methyllylcanonitine -- αCTx α-conotoxin MII; α, β-methylene ATP (PubChem CID:91557) -- Cytisine (PubChem CID:10235) -- NF023 (PubChem CID:4465) -- PPADS (PubChem CID:6093163) -- Nicotine (PubChem CID:942) -- Tubocurarine (PubChem CID:6000) -- DHβE (PubChem CID:31762) -- ATP (PubChem CID:5957) -- Epibatidine (PubChem CID:3073763) -- Methyllycaconitine (PubChem CID:5288811); Neuropsychopharmacology -- Periodicals; Autonomic Agents -- Periodicals; Neuropsychopharmacologie -- Périodiques; Neuropsychopharmacology; Periodicals; Electronic journals; 615.78
• DOI: 10.1016/j.neuropharm.2016.01.022
• Languages: English
• ISSNs: 0028-3908

Abstract

Abstract: Previous studies documented a cross-talk between purinergic P2X (P2XR) and nicotinic acetylcholine receptors (nAChR) in heterologous expression systems and peripheral preparations. We now investigated if this occurred in native brain preparations and probed its physiological function. We found that P2XR and nAChR were enriched in hippocampal terminals, where both P2X1-3R and α3, but not α4, nAChR subunits were located in the active zone and in dopamine-β-hydroxylase-positive hippocampal terminals. Notably, P2XR ligands displaced nAChR binding and nAChR ligands displaced P2XR binding to hippocampal synaptosomes. In addition, a negative P2XR/nAChR cross-talk was observed in the control of the evoked release of noradrenaline from rat hippocampal synaptosomes, characterized by a less-than-additive facilitatory effect upon co-activation of both receptors. This activity-dependent cross-inhibition was confirmed in Xenopus oocytes transfected with P2X1-3Rs and α3β2 (but not α4β2) nAChR. Besides, P2X2 co-immunoprecipitated α3β2 (but not α4β2) nAChR, both in HEK cells and rat hippocampal membranes indicating that this functional interaction is supported by a physical association between P2XR and nAChR. Moreover, eliminating extracellular ATP with apyrase in hippocampal slices promoted the inhibitory effect of the nAChR antagonist tubocurarine on noradrenaline release induced by high- but not low-frequency stimulation. Overall, these results provide integrated biochemical, pharmacological and functional evidence showing that P2X1-3R and α3β2 nAChR are physically and functionally interconnected at the presynaptic level to control excessive noradrenergic terminal activation upon intense synaptic firing in the hippocampus. Graphical abstract: Highlights: Presynaptic P2XR-nAChR receptor–receptor interaction in the rat hippocampus. Cross-inhibition between P2XR and nAChR in the control of noradrenaline release. Physical and functional interaction between presynaptic P2X1-3 and α3β2 receptors. Presynaptic P2XR-nAChR interaction occurs at high-frequency stimulation.