title: Prolonged nicotine exposure down-regulates presynaptic NMDA receptors in dopaminergic terminals of the rat nucleus accumbens.
abstract: The presynaptic control of dopamine release in the nucleus accumbens (NAc) by glutamate and acetylcholine has a profound impact on reward signaling. Here we provide immunocytochemical and neurochemical evidence supporting the co-localization and functional interaction between nicotinic acetylcholine receptors (nAChRs) and N-methyl-D-aspartic acid (NMDA) receptors in dopaminergic terminals of the NAc. Most NAc dopaminergic terminals possessed the nAChR α4 subunit and the pre-exposure of synaptosomes to nicotine (30 μM) or to the α4β2-containing nAChR agonist 5IA85380 (10 nM) selectively inhibited the NMDA (100 μM)-evoked, but not the 4-aminopyridine (10 μM)-evoked, [(3)H] dopamine outflow; this inhibition was blunted by mecamylamine (10 μM). Nicotine and 5IA85380 pretreatment also inhibited the NMDA (100 μM)-evoked increase of calcium levels in single nerve terminals, an effect prevented by dihydro-β-erythroidine (1 μM). This supports a functional interaction between α4β2-containing nAChR and NMDA receptors within the same terminal, as supported by the immunocytochemical co-localization of α4 and GluN1 subunits in individual NAc dopaminergic terminals. The NMDA-evoked [(3)H]dopamine outflow was blocked by MK801 (1 μM) and inhibited by the selective GluN2B-selective antagonists ifenprodil (1 μM) and RO 25-6981 (1 μM), but not by the GluN2A-preferring antagonists CPP-19755 (1 μM) and ZnCl2 (1 nM). Notably, nicotine pretreatment significantly decreased the density of biotin-tagged GluN2B proteins in NAc synaptosomes. These results show that nAChRs dynamically and negatively regulate NMDA receptors in NAc dopaminergic terminals through the internalization of GluN2B receptors.
authors.affiliation: Department of Pharmacy, University of Genoa, Italy.
authors.forename: Alessia
authors.initials: A
authors.lastname: Salamone
authors.affiliation: Department of Pharmacy, University of Genoa, Italy.
authors.forename: Stefania
authors.initials: S
authors.lastname: Zappettini
authors.affiliation: Department of Pharmacy, University of Genoa, Italy.
authors.forename: Massimo
authors.initials: M
authors.lastname: Grilli
authors.affiliation: Department of Pharmacy, University of Genoa, Italy.
authors.forename: Guendalina
authors.initials: G
authors.lastname: Olivero
authors.affiliation: CNC-Center for Neuroscience and Cell Biology, University of Coimbra, Portugal; Faculty of Medicine, University of Coimbra, Portugal.
authors.forename: Paula
authors.initials: P
authors.lastname: Agostinho
authors.affiliation: Faculty of Life Sciences, University of Coimbra, Portugal; CNC-Center for Neuroscience and Cell Biology, University of Coimbra, Portugal.
authors.forename: Angelo R
authors.initials: AR
authors.lastname: Tomé
authors.affiliation: Department of Pharmacy, University of Genoa, Italy.
authors.forename: Jiayang
authors.initials: J
authors.lastname: Chen
authors.affiliation: Department of Pharmacy, University of Genoa, Italy; Center of Excellence for Biomedical Research, University of Genoa, Italy.
authors.forename: Anna
authors.initials: A
authors.lastname: Pittaluga
authors.affiliation: CNC-Center for Neuroscience and Cell Biology, University of Coimbra, Portugal; Faculty of Medicine, University of Coimbra, Portugal.
authors.forename: Rodrigo A
authors.initials: RA
authors.lastname: Cunha
authors.affiliation: Department of Pharmacy, University of Genoa, Italy; Center of Excellence for Biomedical Research, University of Genoa, Italy. Electronic address: mario.marchi@tin.it.
authors.forename: Mario
authors.initials: M
authors.lastname: Marchi
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism; D004298:Dopamine / Q000378:metabolism; D059290:Dopaminergic Neurons / Q000187:drug effects* / Q000378:metabolism; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D008297:Male; D016202:N-Methylaspartate / Q000378:metabolism; D009538:Nicotine / Q000494:pharmacology*; D018722:Nicotinic Agonists / Q000494:pharmacology*; D018733:Nicotinic Antagonists / Q000494:pharmacology; D009714:Nucleus Accumbens / Q000187:drug effects* / Q000378:metabolism; D026902:Potassium Channel Blockers / Q000494:pharmacology; D017729:Presynaptic Terminals / Q000187:drug effects* / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D016194:Receptors, N-Methyl-D-Aspartate / Q000037:antagonists & inhibitors / Q000378:metabolism*; D011978:Receptors, Nicotinic / Q000378:metabolism; D013574:Synaptosomes / Q000187:drug effects / Q000378:metabolism
chemical_list: D002118:Calcium; D004298:Dopamine; D018691:Excitatory Amino Acid Antagonists; D016202:N-Methylaspartate; D009538:Nicotine; D018722:Nicotinic Agonists; D018733:Nicotinic Antagonists; D026902:Potassium Channel Blockers; D016194:Receptors, N-Methyl-D-Aspartate; D011978:Receptors, Nicotinic; C121001:NR2B NMDA receptor; C403531:nicotinic receptor alpha4beta2
keywords: Calcium levels; Isolated nerve endings; NMDA receptors; Neurotransmitter release; Nicotinic receptors; Nucleus accumbens