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Lee R, Kim G, Kim S. Co-activation of selective nicotinic acetylcholine receptor subtypes is required to reverse hippocampal network dysfunction and prevent fear memory loss in Alzheimer's disease. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.07.08.602576. [PMID: 39026693 PMCID: PMC11257460 DOI: 10.1101/2024.07.08.602576] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/20/2024]
Abstract
Alzheimer's disease (AD) is the most common form of dementia with no known cause and cure. Research suggests that a reduction of GABAergic inhibitory interneurons' activity in the hippocampus by beta-amyloid peptide (Aβ) is a crucial trigger for cognitive impairment in AD via hyperexcitability. Therefore, enhancing hippocampal inhibition is thought to be protective against AD. However, hippocampal inhibitory cells are highly diverse, and these distinct interneuron subtypes differentially regulate hippocampal inhibitory circuits and cognitive processes. Moreover, Aβ unlikely affects all subtypes of inhibitory interneurons in the hippocampus equally. Hence, identifying the affected interneuron subtypes in AD to enhance hippocampal inhibition optimally is conceptually and practically challenging. We have previously found that Aβ selectively binds to two of the three major hippocampal nicotinic acetylcholine receptor (nAChR) subtypes, α7- and α4β2-nAChRs, but not α3β4-nAChRs, and inhibits these two receptors in cultured hippocampal inhibitory interneurons to decrease their activity, leading to hyperexcitation and synaptic dysfunction in excitatory neurons. We have also revealed that co-activation of α7- and α4β2-nAChRs is required to reverse the Aβ-induced adverse effects in hippocampal excitatory neurons. Here, we discover that α7- and α4β2-nAChRs predominantly control the nicotinic cholinergic signaling and neuronal activity in hippocampal parvalbumin-positive (PV+) and somatostatin-positive (SST+) inhibitory interneurons, respectively. Furthermore, we reveal that co-activation of these receptors is necessary to reverse hippocampal network dysfunction and fear memory loss in the amyloid pathology model mice. We thus suggest that co-activation of PV+ and SST+ cells is a novel strategy to reverse hippocampal dysfunction and cognitive decline in AD.
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Patel C, Patel R, Kesharwani A, Rao L, Jain NS. Central cholinergic transmission modulates endocannabinoid-induced marble-burying behavior in mice. Behav Brain Res 2024; 476:115252. [PMID: 39278464 DOI: 10.1016/j.bbr.2024.115252] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2024] [Revised: 08/30/2024] [Accepted: 09/12/2024] [Indexed: 09/18/2024]
Abstract
Central cholinergic system and endocannabinoid, anandamide exhibits anti-compulsive-like behavior in mice. However, the role of the central cholinergic system in the anandamide-induced anti-compulsive-like behavior is still unexplored. Therefore, the present study assessed the role of central cholinergic transmission in the anandamide-induced anti-compulsive activity using a marble-burying behavior (MBB) model in mice. The modulation in the anandamide-induced effect on MBB was evaluated using mice with altered central cholinergic transmission achieved by pretreatment (i.c.v.) with various cholinergic agents like acetylcholine (ACh), acetylcholinesterase inhibitor (AChEI), neostigmine, nicotine, mAChR antagonist, atropine, and nAChR antagonist, mecamylamine. The influence of anandamide treatment on the brain AChE activity was also evaluated. The results revealed that i.c.v. injection of anandamide (10, 20 µg/mouse, i.c.v.) dose-dependently reduced MBB in mice. Moreover, anandamide in all the tested doses inhibited the brain AChE activity indicating the role of an enhanced central cholinergic transmission in its anti-compulsive-like effect . Furthermore, the anti-compulsive-like effect of anandamide (20 µg/mouse, i.c.v.) was found to be enhanced in mice centrally pre-treated with, ACh (0.1 µg/mouse, i.c.v.) or AChEI, neostigmine (0.3 µg/mouse, i.c.v.). In addition, the anandamide-induced anti-compulsive-like effect was significantly increased in mice pre-treated with a low dose of nicotine (0.1 µg/mouse, i.c.v.) while, it was attenuated by the higher dose of nicotine (2 µg/mouse, i.c.v.). On the other hand, the anandamide (20 µg/mouse, i.c.v.) induced anti-compulsive-like effect was found to be diminished in mice pre-treated with mAChR antagonist, atropine (0.1, 0.5 µg/mouse, i.c.v.) and pre-injection of nAChR antagonist, mecamylamine (0.1, 0.5 µg/mouse, i.c.v.) potentiated the anandamide induced anti-compulsive-like response in mice. Thus, the present investigation delineates the modulatory role of an enhanced central cholinergic transmission in the anandamide-induced anti-compulsive-like behavior in mice by inhibition of brain AChE or via muscarinic and nicotinic receptors mediated mechanism.
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Affiliation(s)
- Chhatrapal Patel
- Department of Pharmacy, Guru Ghasidas Vishwavidyalaya, Koni, Bilaspur, Chhattisgarh, India
| | - Richa Patel
- Department of Pharmacy, Guru Ghasidas Vishwavidyalaya, Koni, Bilaspur, Chhattisgarh, India
| | - Anuradha Kesharwani
- Department of Pharmacy, Guru Ghasidas Vishwavidyalaya, Koni, Bilaspur, Chhattisgarh, India
| | - Laxmi Rao
- Department of Pharmacy, Guru Ghasidas Vishwavidyalaya, Koni, Bilaspur, Chhattisgarh, India
| | - Nishant Sudhir Jain
- Department of Pharmacy, Guru Ghasidas Vishwavidyalaya, Koni, Bilaspur, Chhattisgarh, India.
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Abbondanza A, Urushadze A, Alves-Barboza AR, Janickova H. Expression and function of nicotinic acetylcholine receptors in specific neuronal populations: Focus on striatal and prefrontal circuits. Pharmacol Res 2024; 204:107190. [PMID: 38704107 DOI: 10.1016/j.phrs.2024.107190] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/26/2024] [Revised: 04/19/2024] [Accepted: 04/20/2024] [Indexed: 05/06/2024]
Abstract
Nicotinic acetylcholine receptors (nAChRs) are widely expressed in the central nervous system and play an important role in the control of neural functions including neuronal activity, transmitter release and synaptic plasticity. Although the common subtypes of nAChRs are abundantly expressed throughout the brain, their expression in different brain regions and by individual neuronal types is not homogeneous or incidental. In recent years, several studies have emerged showing that particular subtypes of nAChRs are expressed by specific neuronal populations in which they have major influence on the activity of local circuits and behavior. It has been demonstrated that even nAChRs expressed by relatively rare neuronal types can induce significant changes in behavior and contribute to pathological processes. Depending on the identity and connectivity of the particular nAChRs-expressing neuronal populations, the activation of nAChRs can have distinct or even opposing effects on local neuronal signaling. In this review, we will summarize the available literature describing the expression of individual nicotinic subunits by different neuronal types in two crucial brain regions, the striatum and the prefrontal cortex. The review will also briefly discuss nicotinic expression in non-neuronal, glial cells, as they cannot be ignored as potential targets of nAChRs-modulating drugs. The final section will discuss options that could allow us to target nAChRs in a neuronal-type-specific manner, not only in the experimental field, but also eventually in clinical practice.
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Affiliation(s)
- Alice Abbondanza
- Laboratory of Neurochemistry, Institute of Physiology of the Czech Academy of Sciences, Prague 14200, Czech Republic
| | - Anna Urushadze
- Laboratory of Neurochemistry, Institute of Physiology of the Czech Academy of Sciences, Prague 14200, Czech Republic
| | - Amanda Rosanna Alves-Barboza
- Laboratory of Neurochemistry, Institute of Physiology of the Czech Academy of Sciences, Prague 14200, Czech Republic
| | - Helena Janickova
- Laboratory of Neurochemistry, Institute of Physiology of the Czech Academy of Sciences, Prague 14200, Czech Republic.
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Abreu SA, Laursen SA, Perrin KL, Tahas SA, Bertelsen MF. COMPARISON OF THREE MIDAZOLAM-BASED SEDATION PROTOCOLS IN BUDGERIGARS ( MELOPSITTACUS UNDULATUS) AND BLACK-CHEEKED LOVEBIRDS ( AGAPORNIS NIGRIGENIS). J Zoo Wildl Med 2024; 55:111-124. [PMID: 38453494 DOI: 10.1638/2022-0124] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/11/2023] [Indexed: 03/09/2024] Open
Abstract
This randomized, crossover study evaluated three sedation protocols administered subcutaneously in nine budgerigars (Melopsittacus undulatus) and nine black-cheeked lovebirds (Agapornis nigrigenis). All protocols included midazolam (5 mg/kg), combined with butorphanol (5 mg/kg) (BM), medetomidine (20 lg/kg) (MM), or alfaxalone (13 mg/kg) (AM). Mortalities from suspected cardiorespiratory arrest were observed when AM was used in lovebirds, even after reduction of alfaxalone dosage to 3 mg/kg, and therefore this protocol was excluded from further use in this species. Induction and recovery times were recorded and their quality assessed. Sedation depth and heart and respiratory rates were measured every 5 min and radiographic positioning was attempted at 10 and 20 min. At 30 min, midazolam and medetomidine were reversed with flumazenil (0.05 mg/kg, SC), and atipamezole (0.2 mg/kg, SC), respectively. MM consistently provided deep sedation in both species, with successful radiographic positioning at every attempt. As expected, heart rate was often lower with MM than with other protocols, but no associated complications were noted. In budgerigars, BM had the lowest radiographic positioning success rate (10 min: 5/9, 20 min: 3/9), whereas in lovebirds it provided significantly deeper sedation (P < 0.001), allowing radiographic positioning in all subjects. In both species, BM provided the shortest recovery times. AM resulted in reliable radiographic positioning of all budgerigars at 10 min, but not at 20 min (5/ 9), and provided consistently poor recoveries. This study highlights how differently two psittacine species of similar size may react to the same sedation protocols. AM sedation cannot be fully reversed and produced significant undesirable effects, several of which have been previously reported with alfaxalone administration to avian species. The authors therefore caution against using alfaxalone-midazolam combinations in budgerigars and black-cheeked lovebirds. Both BM and MM provided reliable sedation in these species, and appear to be suitable alternatives to AM.
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Affiliation(s)
- Sara A Abreu
- Center for Zoo and Wild Animal Health, Copenhagen Zoo, Frederiksberg, 2000, Denmark,
| | - Sophie A Laursen
- Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Frederiksberg, 1870, Denmark
| | - Kathryn L Perrin
- Center for Zoo and Wild Animal Health, Copenhagen Zoo, Frederiksberg, 2000, Denmark
| | - Stamatios A Tahas
- Center for Zoo and Wild Animal Health, Copenhagen Zoo, Frederiksberg, 2000, Denmark
| | - Mads F Bertelsen
- Center for Zoo and Wild Animal Health, Copenhagen Zoo, Frederiksberg, 2000, Denmark
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Patel C, Patel R, Maturkar V, Jain NS. Central cholinergic transmission affects the compulsive-like behavior of mice in marble-burying test. Brain Res 2024; 1825:148713. [PMID: 38097126 DOI: 10.1016/j.brainres.2023.148713] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2023] [Revised: 12/02/2023] [Accepted: 12/11/2023] [Indexed: 12/19/2023]
Abstract
The presence of the cholinergic system in the brain areas implicated in the precipitation of obsessive-compulsive behavior (OCB) has been reported but the exact role of the central cholinergic system therein is still unexplored. Therefore, the current study assessed the effect of cholinergic analogs on central administration on the marble-burying behavior (MBB) of mice, a behavior correlated with OCB. The result reveals that the enhancement of central cholinergic transmission in mice achieved by intracerebroventricular (i.c.v.) injection of acetylcholine (0.01 µg) (Subeffective: 0.1 and 0.5 µg), cholinesterase inhibitor, neostigmine (0.1, 0.3, 0.5 µg/mouse) and neuronal nicotinic acetylcholine receptor agonist, nicotine (0.1, 2 µg/mouse) significantly attenuated the number of marbles buried by mice in MBB test without affecting basal locomotor activity. Similarly, central injection of mAChR antagonist, atropine (0.1, 0.5, 5 µg/mouse), nAChR antagonist, mecamylamine (0.1, 0.5, 3 µg/mouse) per se also reduced the MBB in mice, indicative of anti-OCB like effect of all the tested cholinergic mAChR or nAChR agonist and antagonist. Surprisingly, i.c.v. injection of acetylcholine (0.01 µg), and neostigmine (0.1 µg) failed to elicit an anti-OCB-like effect in mice pre-treated (i.c.v.) with atropine (0.1 µg), or mecamylamine (0.1 µg). Thus, the findings of the present investigationdelineate the role of central cholinergic transmission in the compulsive-like behavior of mice probably via mAChR or nAChR stimulation.
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Affiliation(s)
- Chhatrapal Patel
- Department of Pharmacy, Guru Ghasidas Vishwavidyalaya, Koni, Bilaspur, Chhattisgarh, India
| | - Richa Patel
- Department of Pharmacy, Guru Ghasidas Vishwavidyalaya, Koni, Bilaspur, Chhattisgarh, India
| | - Vaibhav Maturkar
- Department of Pharmacy, Guru Ghasidas Vishwavidyalaya, Koni, Bilaspur, Chhattisgarh, India
| | - Nishant Sudhir Jain
- Department of Pharmacy, Guru Ghasidas Vishwavidyalaya, Koni, Bilaspur, Chhattisgarh, India.
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Jiménez-Pompa A, Arribas RL, McIntosh JM, Albillos A. Differential tyrosine and serine/threonine phosphorylation/dephosphorylation pathways regulate the expression of α7 versus α3β4 nicotinic receptor subtypes in mouse hippocampal neurons. Biochem Biophys Res Commun 2023; 684:149115. [PMID: 37879250 DOI: 10.1016/j.bbrc.2023.10.047] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2023] [Revised: 09/28/2023] [Accepted: 10/12/2023] [Indexed: 10/27/2023]
Abstract
We have recently reported that α7 and α3β4 nicotinic acetylcholine receptor (nAChR) subtypes are expressed in human chromaffin cells in the plasma membrane where they colocalize and physically interact. The present study was designed to evaluate whether those receptor subtypes also colocalize at the central nervous system to mutually interact, and whether their expression and colocalization are regulated by phosphorylation/dephosphorylation processes, as they are in human chromaffin cells. We have here found that in isolated and maintained in culture mouse hippocampal neurons, nAChR expression and colocalization of α7, but not α3β4, nAChR subtypes decreased by tyrosine (Tyr)- and serine/threonine (Ser/Thr)-phosphatase inhibition. However, Tyr-kinase inhibition or protein-phosphatase 2A (PP2A) activation increased α3β4 nAChR expression, diminishing receptor subtypes colocalization. Furthermore, colocalization is not recovered if the inhibitors of Tyr-phosphatase and kinases, or the inhibitor of Ser/Thr-phosphatases and the activator of PP2A are applied together. Therefore, regulation of α7 and α3β4 nAChR subtypes expression by Tyr- and Ser/Thr kinases and phosphatases exhibit differential mechanisms in mouse hippocampal neurons. Colocalization of nAChR subtypes, however, is altered by any maneuver that affects these kinases or phosphatases, which might have consequences in the functional activity of nAChR subtypes.
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Affiliation(s)
- Amanda Jiménez-Pompa
- Departamento de Farmacología y Terapéutica, Universidad Autónoma de Madrid, 28029, Madrid, Spain
| | - Raquel L Arribas
- Departamento de Ciencias Básicas de la Salud, Facultad de Ciencias de la Salud, Universidad Rey Juan Carlos, 28922, Alcorcón, Madrid, Spain
| | - J Michael McIntosh
- Departments of Biology and Psychiatry, University of Utah, Salt Lake City, UT, USA; George E. Whalen Veterans Affairs Medical Center, Salt Lake City, UT, USA
| | - Almudena Albillos
- Departamento de Farmacología y Terapéutica, Universidad Autónoma de Madrid, 28029, Madrid, Spain; Instituto Ramón y Cajal de Investigación Biosanitaria (IRYCIS), 28034, Madrid, Spain.
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Stefano MED, Ferretti V, Mozzetta C. Synaptic alterations as a neurodevelopmental trait of Duchenne muscular dystrophy. Neurobiol Dis 2022; 168:105718. [PMID: 35390481 DOI: 10.1016/j.nbd.2022.105718] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2021] [Revised: 03/28/2022] [Accepted: 03/29/2022] [Indexed: 01/14/2023] Open
Abstract
Dystrophinopaties, e.g., Duchenne muscular dystrophy (DMD), Becker muscular dystrophy and X-linked dilated cardiomyopathy are inherited neuromuscular diseases, characterized by progressive muscular degeneration, which however associate with a significant impact on general system physiology. The more severe is the pathology and its diversified manifestations, the heavier are its effects on organs, systems, and tissues other than muscles (skeletal, cardiac and smooth muscles). All dystrophinopaties are characterized by mutations in a single gene located on the X chromosome encoding dystrophin (Dp427) and its shorter isoforms, but DMD is the most devasting: muscular degenerations manifests within the first 4 years of life, progressively affecting motility and other muscular functions, and leads to a fatal outcome between the 20s and 40s. To date, after years of studies on both DMD patients and animal models of the disease, it has been clearly demonstrated that a significant percentage of DMD patients are also afflicted by cognitive, neurological, and autonomic disorders, of varying degree of severity. The anatomical correlates underlying neural functional damages are established during embryonic development and the early stages of postnatal life, when brain circuits, sensory and motor connections are still maturing. The impact of the absence of Dp427 on the development, differentiation, and consolidation of specific cerebral circuits (hippocampus, cerebellum, prefrontal cortex, amygdala) is significant, and amplified by the frequent lack of one or more of its lower molecular mass isoforms. The most relevant aspect, which characterizes DMD-associated neurological disorders, is based on morpho-functional alterations of selective synaptic connections within the affected brain areas. This pathological feature correlates neurological conditions of DMD to other severe neurological disorders, such as schizophrenia, epilepsy and autistic spectrum disorders, among others. This review discusses the organization and the role of the dystrophin-dystroglycan complex in muscles and neurons, focusing on the neurological aspect of DMD and on the most relevant morphological and functional synaptic alterations, in both central and autonomic nervous systems, described in the pathology and its animal models.
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Affiliation(s)
- Maria Egle De Stefano
- Department of Biology and Biotechnology "Charles Darwin", Sapienza University of Rome, 00185 Rome, Italy; Center for Research in Neurobiology Daniel Bovet, Sapienza University of Rome, 00185 Rome, Italy.
| | - Valentina Ferretti
- Department of Biology and Biotechnology "Charles Darwin", Sapienza University of Rome, 00185 Rome, Italy; Center for Research in Neurobiology Daniel Bovet, Sapienza University of Rome, 00185 Rome, Italy
| | - Chiara Mozzetta
- Institute of Molecular Biology and Pathology (IBPM), National Research Council (CNR) of Italy c/o Department of Biology and Biotechnology "Charles Darwin", Sapienza University of Rome, 00185 Rome, Italy
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Stone TW. Relationships and Interactions between Ionotropic Glutamate Receptors and Nicotinic Receptors in the CNS. Neuroscience 2021; 468:321-365. [PMID: 34111447 DOI: 10.1016/j.neuroscience.2021.06.007] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2021] [Revised: 06/03/2021] [Accepted: 06/04/2021] [Indexed: 02/07/2023]
Abstract
Although ionotropic glutamate receptors and nicotinic receptors for acetylcholine (ACh) have usually been studied separately, they are often co-localized and functionally inter-dependent. The objective of this review is to survey the evidence for interactions between the two receptor families and the mechanisms underlying them. These include the mutual regulation of subunit expression, which change the NMDA:AMPA response balance, and the existence of multi-functional receptor complexes which make it difficult to distinguish between individual receptor sites, especially in vivo. This is followed by analysis of the functional relationships between the receptors from work on transmitter release, cellular electrophysiology and aspects of behavior where these can contribute to understanding receptor interactions. It is clear that nicotinic receptors (nAChRs) on axonal terminals directly regulate the release of glutamate and other neurotransmitters, α7-nAChRs generally promoting release. Hence, α7-nAChR responses will be prevented not only by a nicotinic antagonist, but also by compounds blocking the indirectly activated glutamate receptors. This accounts for the apparent anticholinergic activity of some glutamate antagonists, including the endogenous antagonist kynurenic acid. The activation of presynaptic nAChRs is by the ambient levels of ACh released from pre-terminal synapses, varicosities and glial cells, acting as a 'volume neurotransmitter' on synaptic and extrasynaptic sites. In addition, ACh and glutamate are released as CNS co-transmitters, including 'cholinergic' synapses onto spinal Renshaw cells. It is concluded that ACh should be viewed primarily as a modulator of glutamatergic neurotransmission by regulating the release of glutamate presynaptically, and the location, subunit composition, subtype balance and sensitivity of glutamate receptors, and not primarily as a classical fast neurotransmitter. These conclusions and caveats should aid clarification of the sites of action of glutamate and nicotinic receptor ligands in the search for new centrally-acting drugs.
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Affiliation(s)
- Trevor W Stone
- The Kennedy Institute of Rheumatology, University of Oxford, Oxford OX3 7FY, UK; Institute of Neuroscience, University of Glasgow, G12 8QQ, UK.
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Roberts JP, Stokoe SA, Sathler MF, Nichols RA, Kim S. Selective coactivation of α7- and α4β2-nicotinic acetylcholine receptors reverses beta-amyloid-induced synaptic dysfunction. J Biol Chem 2021; 296:100402. [PMID: 33571523 PMCID: PMC7961090 DOI: 10.1016/j.jbc.2021.100402] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2020] [Revised: 02/02/2021] [Accepted: 02/07/2021] [Indexed: 01/04/2023] Open
Abstract
Beta-amyloid (Aβ) has been recognized as an early trigger in the pathogenesis of Alzheimer's disease (AD) leading to synaptic and cognitive impairments. Aβ can alter neuronal signaling through interactions with nicotinic acetylcholine receptors (nAChRs), contributing to synaptic dysfunction in AD. The three major nAChR subtypes in the hippocampus are composed of α7-, α4β2-, and α3β4-nAChRs. Aβ selectively affects α7- and α4β2-nAChRs, but not α3β4-nAChRs in hippocampal neurons, resulting in neuronal hyperexcitation. However, how nAChR subtype selectivity for Aβ affects synaptic function in AD is not completely understood. Here, we showed that Aβ associated with α7- and α4β2-nAChRs but not α3β4-nAChRs. Computational modeling suggested that two amino acids in α7-nAChRs, arginine 208 and glutamate 211, were important for the interaction between Aβ and α7-containing nAChRs. These residues are conserved only in the α7 and α4 subunits. We therefore mutated these amino acids in α7-containing nAChRs to mimic the α3 subunit and found that mutant α7-containing receptors were unable to interact with Aβ. In addition, mutant α3-containing nAChRs mimicking the α7 subunit interact with Aβ. This provides direct molecular evidence for how Aβ selectively interacted with α7- and α4β2-nAChRs, but not α3β4-nAChRs. Selective coactivation of α7- and α4β2-nAChRs also sufficiently reversed Aβ-induced AMPA receptor dysfunction, including Aβ-induced reduction of AMPA receptor phosphorylation and surface expression in hippocampal neurons. Moreover, costimulation of α7- and α4β2-nAChRs reversed the Aβ-induced disruption of long-term potentiation. These findings support a novel mechanism for Aβ's impact on synaptic function in AD, namely, the differential regulation of nAChR subtypes.
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Affiliation(s)
- Jessica P Roberts
- Molecular, Cellular and Integrative Neurosciences Program, Colorado State University, Fort Collins, Colorado, USA; Department of Biomedical Sciences, Colorado State University, Fort Collins, Colorado, USA
| | - Sarah A Stokoe
- Molecular, Cellular and Integrative Neurosciences Program, Colorado State University, Fort Collins, Colorado, USA; Department of Biomedical Sciences, Colorado State University, Fort Collins, Colorado, USA
| | - Matheus F Sathler
- Department of Biomedical Sciences, Colorado State University, Fort Collins, Colorado, USA
| | - Robert A Nichols
- Department of Cell and Molecular Biology, University of Hawai'i at Manoa, Honolulu, Hawaii, USA
| | - Seonil Kim
- Molecular, Cellular and Integrative Neurosciences Program, Colorado State University, Fort Collins, Colorado, USA; Department of Biomedical Sciences, Colorado State University, Fort Collins, Colorado, USA.
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10
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Scholze P, Huck S. The α5 Nicotinic Acetylcholine Receptor Subunit Differentially Modulates α4β2 * and α3β4 * Receptors. Front Synaptic Neurosci 2020; 12:607959. [PMID: 33343327 PMCID: PMC7744819 DOI: 10.3389/fnsyn.2020.607959] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2020] [Accepted: 11/11/2020] [Indexed: 11/30/2022] Open
Abstract
Nicotine, the principal reinforcing compound in tobacco, acts in the brain by activating neuronal nicotinic acetylcholine receptors (nAChRs). This review summarizes our current knowledge regarding how the α5 accessory nAChR subunit, encoded by the CHRNA5 gene, differentially modulates α4β2* and α3β4* receptors at the cellular level. Genome-wide association studies have linked a gene cluster in chromosomal region 15q25 to increased susceptibility to nicotine addiction, lung cancer, chronic obstructive pulmonary disease, and peripheral arterial disease. Interestingly, this gene cluster contains a non-synonymous single-nucleotide polymorphism (SNP) in the human CHRNA5 gene, causing an aspartic acid (D) to asparagine (N) substitution at amino acid position 398 in the α5 nAChR subunit. Although other SNPs have been associated with tobacco smoking behavior, efforts have focused predominantly on the D398 and N398 variants in the α5 subunit. In recent years, significant progress has been made toward understanding the role that the α5 nAChR subunit—and the role of the D398 and N398 variants—plays on nAChR function at the cellular level. These insights stem primarily from a wide range of experimental models, including receptors expressed heterologously in Xenopus oocytes, various cell lines, and neurons derived from human induced pluripotent stem cells (iPSCs), as well as endogenous receptors in genetically engineered mice and—more recently—rats. Despite providing a wealth of available data, however, these studies have yielded conflicting results, and our understanding of the modulatory role that the α5 subunit plays remains incomplete. Here, we review these reports and the various techniques used for expression and analysis in order to examine how the α5 subunit modulates key functions in α4β2* and α3β4* receptors, including receptor trafficking, sensitivity, efficacy, and desensitization. In addition, we highlight the strikingly different role that the α5 subunit plays in Ca2+ signaling between α4β2* and α3β4* receptors, and we discuss whether the N398 α5 subunit variant can partially replace the D398 variant.
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Affiliation(s)
- Petra Scholze
- Department of Pathobiology of the Nervous System, Center for Brain Research, Medical University of Vienna, Vienna, Austria
| | - Sigismund Huck
- Department of Pathobiology of the Nervous System, Center for Brain Research, Medical University of Vienna, Vienna, Austria
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11
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Laliberté G, Othman R, Vaucher E. Mesoscopic Mapping of Stimulus-Selective Response Plasticity in the Visual Pathways Modulated by the Cholinergic System. Front Neural Circuits 2020; 14:38. [PMID: 32719589 PMCID: PMC7350895 DOI: 10.3389/fncir.2020.00038] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2020] [Accepted: 05/22/2020] [Indexed: 11/13/2022] Open
Abstract
The cholinergic potentiation of visual conditioning enhances visual acuity and discrimination of the trained stimulus. To determine if this also induces long-term plastic changes on cortical maps and connectivity in the visual cortex and higher associative areas, mesoscopic calcium imaging was performed in head-fixed awake GCaMP6s adult mice before and after conditioning. The conditioned stimulus (0.03 cpd, 30°, 100% contrast, 1 Hz-drifting gratings) was presented 10 min daily for a week. Saline or Donepezil (DPZ, 0.3 mg/kg, s.c.), a cholinesterase inhibitor that potentiates cholinergic transmission, were injected prior to each conditioning session and compared to a sham-conditioned group. Cortical maps of resting state and evoked response to the monocular presentation of conditioned or non-conditioned stimulus (30°, 50 and 75% contrast; 90°, 50, 75, and 100% contrast) were established. Amplitude, duration, and latency of the peak response, as well as size of activation were measured in the primary visual cortex (V1), secondary visual areas (AL, A, AM, PM, LM, RL), retrosplenial cortex (RSC), and higher cortical areas. Visual stimulation increased calcium signaling in all primary and secondary visual areas, the RSC, but no other cortices. There were no significant effects of sham-conditioning or conditioning alone, but DPZ treatment during conditioning significantly decreased the integrated neuronal activity of superficial layers evoked by the conditioned stimulus in V1, AL, PM, and LM. The activity of downstream cortical areas was not changed. The size of the activated area was decreased in V1 and PM, and the signal-to-noise ratio was decreased in AL and PM. Interestingly, signal correlation was seen only between V1, the ventral visual pathway, and the RSC, and was decreased by DPZ administration. The resting state activity was slightly correlated and rarely affected by treatments, except between binocular and monocular V1 in both hemispheres. In conclusion, cholinergic potentiation of visual conditioning induced change in visual processing in the superficial cortical layers. This effect might be a key mechanism in the establishment of the fine cortical tuning in response to the conditioned visual stimulus.
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Affiliation(s)
- Guillaume Laliberté
- Laboratoire de Neurobiologie de la Cognition Visuelle, École d'Optométrie, Université de Montréal, Montréal, QC, Canada
| | - Rahmeh Othman
- Laboratoire de Neurobiologie de la Cognition Visuelle, École d'Optométrie, Université de Montréal, Montréal, QC, Canada.,Départment de Pharmacologie et Physiologie, Faculté de Médecine, Université de Montréal, Montréal, QC, Canada
| | - Elvire Vaucher
- Laboratoire de Neurobiologie de la Cognition Visuelle, École d'Optométrie, Université de Montréal, Montréal, QC, Canada
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12
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Montaño-Velázquez BB, Benavides Méndez JC, García-Vázquez FJ, Conde-Vázquez E, Sánchez-Uribe M, Taboada-Murrieta CR, Jáuregui-Renaud K. Influence of Tobacco Smoke Exposure on the Protein Expression of α7 and α4 Nicotinic Acetylcholine Receptors in Squamous Cell Carcinoma Tumors of the Upper Aerodigestive Tract (Out of the Larynx). SUBSTANCE ABUSE-RESEARCH AND TREATMENT 2018; 12:1178221818801316. [PMID: 31068752 PMCID: PMC6495442 DOI: 10.1177/1178221818801316] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/05/2018] [Accepted: 08/10/2018] [Indexed: 12/11/2022]
Abstract
Purpose: To assess protein expression of α7 and α4 nicotinic acetylcholine receptors (nAChR) subtypes in squamous cell carcinoma of the upper aerodigestive track (out of the larynx) according to tobacco smoke exposure, considering the general characteristics of the patients. Methods: The α7 and α4 nAChR subtypes were assessed by immunohistochemistry in tumor samples from 33 patients with novel diagnosis of squamous cell carcinoma of the upper aerodigestive tract (out of the larynx). Results: Current smokers were middle-age men with alcohol consumption, whereas elderly women with no alcohol consumption prevailed among nonsmokers. Expression of α4 nAChR was high in all groups, with an influence of alcohol use, although expression of α7 nAChR was low in current smokers with alcohol use. Expression of α4 with no expression of α7 nAChR was associated with advanced disease. Conclusions: Squamous cell carcinoma tumors of the upper aerodigestive tract (out of the larynx) may show desensitization of α4 nAChR. Advanced disease at diagnosis might be associated with desensitization of α4 with decrease in α7 nAChR.
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Affiliation(s)
- Bertha B Montaño-Velázquez
- Servicio de Otorrinolaringología, CMN La Raza, Instituto Mexicano del Seguro Social, Ciudad de México, México
| | - Juan C Benavides Méndez
- Servicio de Otorrinolaringología, CMN La Raza, Instituto Mexicano del Seguro Social, Ciudad de México, México
| | | | - Ernesto Conde-Vázquez
- Servicio de Otorrinolaringología, CMN La Raza, Instituto Mexicano del Seguro Social, Ciudad de México, México
| | - Magdalena Sánchez-Uribe
- Servicio de Anatomía Patológica, HE CMN La Raza, Instituto Mexicano del Seguro Social, Ciudad de México, México
| | - Cecilia R Taboada-Murrieta
- Servicio de Anatomía Patológica, HE CMN La Raza, Instituto Mexicano del Seguro Social, Ciudad de México, México
| | - Kathrine Jáuregui-Renaud
- Unidad de Investigación Médica en Otoneurología, Instituto Mexicano del Seguro Social, Ciudad de México, México
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13
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Pereira da Silva JD, Campos DV, Nogueira-Bechara FM, Stilhano RS, Han SW, Sinigaglia-Coimbra R, Lima-Landman MTR, Lapa AJ, Souccar C. Altered release and uptake of gamma-aminobutyric acid in the cerebellum of dystrophin-deficient mice. Neurochem Int 2018; 118:105-114. [PMID: 29864448 DOI: 10.1016/j.neuint.2018.06.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2018] [Revised: 05/07/2018] [Accepted: 06/01/2018] [Indexed: 01/08/2023]
Abstract
Dystrophin deficiency caused by mutations of the related gene leads to muscle wasting in Duchenne muscular dystrophy (DMD). Some patients with DMD also present with intellectual disability and various degrees of neurological disorders, which have been related to a decreased number of postsynaptic gamma-aminobutyric acid type A receptors (GABAARs) in the hippocampus (HPC) and cerebellum (CBL). The aim of this study was to examine the relevance of dystrophin in the presynaptic GABAergic function in brain regions in which this protein is normally abundant. [3H]-GABA release, induced by nicotinic receptor (nAChR) activation or K+ depolarization, and [3H]-GABA uptake were determined using synaptosomes extracted from the cortex (CTX), HPC, and CBL of littermate control and mdx mice. Superfusion of the synaptosomes with nicotine or high K+ solutions led to a concentration-dependent and Ca2+-dependent [3H]-GABA release in control and mdx synaptosomes. [3H]-GABA release induced by 10 μM nicotine in mdx CBL synaptosomes was 47% less than that in control mice. K+-induced [3H]-GABA release did not differ between control and mdx synaptosomes. α7-containing and β2-containing nAChRs were involved in nicotine-induced [3H]-GABA release in control and mdx synaptosomes. Kinetic analysis of [3H]-GABA uptake in mdx CBL synaptosomes showed a reduced (50%) half-maximal uptake time (t1/2) and increased (44%) rate of [3H]-GABA uptake (Vmax) compared to controls. The apparent transporter affinity (Km) for GABA was not altered. Our findings show that dystrophin deficiency in mdx mice is associated with significant changes in the release and uptake of GABA in the CBL. These presynaptic alterations may be related to the reported decrease in postsynaptic GABAAR in the same brain region. The results indicate possible dysfunction of GABAergic synapses associated with dystrophin deficiency in the CBL, which may contribute to the cognitive and neurobehavioral disorders in mdx mice and patients with DMD.
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Affiliation(s)
| | - Diego Vannucci Campos
- Department of Pharmacology, Universidade Federal de São Paulo, Escola Paulista de Medicina, SP, Brazil
| | | | - Roberta Sessa Stilhano
- Department of Biophysics, Universidade Federal de São Paulo, Escola Paulista de Medicina, SP, Brazil
| | - Sang Won Han
- Department of Biophysics, Universidade Federal de São Paulo, Escola Paulista de Medicina, SP, Brazil
| | - Rita Sinigaglia-Coimbra
- Electron Microscopy Center, Universidade Federal de São Paulo, Escola Paulista de Medicina, SP, Brazil
| | | | - Antônio José Lapa
- Department of Pharmacology, Universidade Federal de São Paulo, Escola Paulista de Medicina, SP, Brazil; Visiting Professor at Universidade do Estado do Amazonas, Manaus, Amazonas, Brazil
| | - Caden Souccar
- Department of Pharmacology, Universidade Federal de São Paulo, Escola Paulista de Medicina, SP, Brazil.
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14
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Conti MM, Chambers N, Bishop C. A new outlook on cholinergic interneurons in Parkinson's disease and L-DOPA-induced dyskinesia. Neurosci Biobehav Rev 2018; 92:67-82. [PMID: 29782883 DOI: 10.1016/j.neubiorev.2018.05.021] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2017] [Revised: 01/05/2018] [Accepted: 05/16/2018] [Indexed: 02/07/2023]
Abstract
Traditionally, dopamine (DA) and acetylcholine (ACh) striatal systems were considered antagonistic and imbalances or aberrant signaling between these neurotransmitter systems could be detrimental to basal ganglia activity and pursuant motor function, such as in Parkinson's disease (PD) and L-DOPA-induced dyskinesia (LID). Herein, we discuss the involvement of cholinergic interneurons (ChIs) in striatally-mediated movement in a healthy, parkinsonian, and dyskinetic state. ChIs integrate numerous neurotransmitter signals using intrinsic glutamate, serotonin, and DA receptors and convey the appropriate transmission onto nearby muscarinic and nicotinic ACh receptors to produce movement. In PD, severe DA depletion causes abnormal rises in ChI activity which promote striatal signaling to attenuate normal movement. When treating PD with L-DOPA, hyperkinetic side effects, or LID, develop due to increased striatal DA; however, the role of ChIs and ACh transmission, until recently has been unclear. Fortunately, new technology and pharmacological agents have facilitated understanding of ChI function and ACh signaling in the context of LID, thus offering new opportunities to modify existing and discover future therapeutic strategies in movement disorders.
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Affiliation(s)
- Melissa M Conti
- Behavioral Neuroscience Program, Department of Psychology, Binghamton University, 4400 Vestal Parkway East, Binghamton, NY 13902-6000, USA.
| | - Nicole Chambers
- Behavioral Neuroscience Program, Department of Psychology, Binghamton University, 4400 Vestal Parkway East, Binghamton, NY 13902-6000, USA.
| | - Christopher Bishop
- Behavioral Neuroscience Program, Department of Psychology, Binghamton University, 4400 Vestal Parkway East, Binghamton, NY 13902-6000, USA.
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15
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Long-Term Administration of Queen Bee Acid (QBA) to Rodents Reduces Anxiety-Like Behavior, Promotes Neuronal Health and Improves Body Composition. Nutrients 2017; 10:nu10010013. [PMID: 29295499 PMCID: PMC5793241 DOI: 10.3390/nu10010013] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2017] [Revised: 12/15/2017] [Accepted: 12/20/2017] [Indexed: 12/13/2022] Open
Abstract
Background: Queen bee acid (QBA; 10-hydroxy-2-decenoic acid) is the predominant fatty acid in royal jelly (RJ) and has activity at estrogen receptors, which affect brain function and body composition. However, few, long-term studies have assessed QBA effects in brain health and body composition. Methods: Primary hippocampal neurons were treated with QBA (0–30 µM) and challenged with glutamate or hypoxia. QBA was fed to aged, male Sprague-Dawley rats (12–24 mg/kg/day) and to adult male and female Balb/C mice (30–60 mg/kg/day) for ≥3.5 months. Rats were evaluated in a behavioral test battery of brain function. Mice were measured for fat and muscle composition, as well as bone density. Results: QBA increased neuron growth and protected against glutamate challenge and hypoxia challenge. Rats receiving QBA had reduced anxiety-like behavior, increased body weight, and better maintenance of body weight with age. Mice receiving QBA exhibited increased body weight, muscle mass, and adiposity in males, and increased bone density, but decreased adiposity, in females. Conclusions: QBA is an active component of RJ that promotes the growth and protection of neurons, reduces anxiety-like phenotypes, and benefits bone, muscle and adipose tissues in a sex-dependent manner, which further implicates estrogen receptors in the effects of QBA.
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16
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Morud J, Strandberg J, Andrén A, Ericson M, Söderpalm B, Adermark L. Progressive modulation of accumbal neurotransmission and anxiety-like behavior following protracted nicotine withdrawal. Neuropharmacology 2017; 128:86-95. [PMID: 28986279 DOI: 10.1016/j.neuropharm.2017.10.002] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2017] [Revised: 09/25/2017] [Accepted: 10/01/2017] [Indexed: 12/18/2022]
Abstract
Due to the highly addictive properties of nicotine, a low percentage of users successfully maintain cessation for longer periods of time. This might be linked to neuroadaptations elicited by the drug, and understanding progressive changes in neuronal function might provide critical insight into nicotine addiction. We have previously shown that neurotransmission in the nucleus accumbens (nAc), a key brain region with respect to drug reinforcement and relapse, is suppressed for as long as seven months after a brief period of nicotine treatment. Studies were therefore performed to define the temporal properties of these effects, and to assess behavioral correlates to altered neurotransmission. Ex vivo electrophysiology revealed progressive depression of synaptic efficacy in the nAc of rats previously receiving nicotine. In addition, following three months of nicotine withdrawal, the responses to GABAA receptor modulating drugs were blunted together with downregulation of several GABAA receptor subunits. In correlation to reduced accumbal neurotransmission, a reduced anxiety-like behavior; assessed in the elevated plus-maze and marble burying tests, were identified in animals pre-treated with nicotine. Lastly, to test the causal relationship between suppressed excitability in the nAc and reduced anxiety-like behavior, rats received local administration of diazepam in the nAc while monitoring behavioral effects on the elevated plus-maze. These results show that nicotine produces long-lasting changes in the GABAergic system, which are observed first after extended withdrawal. Our data also suggest that nicotine produces a progressive suppression of accumbal excitability, which could result in behavioral alterations that may have implications for further drug intake.
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Affiliation(s)
- Julia Morud
- Addiction Biology Unit, Department of Psychiatry and Neurochemistry, Institute of Neuroscience and Physiology, The Sahlgrenska Academy at the University of Gothenburg, Box 410, 405 30 Gothenburg, Sweden.
| | - Joakim Strandberg
- Department of Physiology, Institute of Neuroscience and Physiology, The Sahlgrenska Academy at the University of Gothenburg, Box 432, 405 30 Gothenburg, Sweden
| | - Anna Andrén
- Addiction Biology Unit, Department of Psychiatry and Neurochemistry, Institute of Neuroscience and Physiology, The Sahlgrenska Academy at the University of Gothenburg, Box 410, 405 30 Gothenburg, Sweden
| | - Mia Ericson
- Addiction Biology Unit, Department of Psychiatry and Neurochemistry, Institute of Neuroscience and Physiology, The Sahlgrenska Academy at the University of Gothenburg, Box 410, 405 30 Gothenburg, Sweden
| | - Bo Söderpalm
- Addiction Biology Unit, Department of Psychiatry and Neurochemistry, Institute of Neuroscience and Physiology, The Sahlgrenska Academy at the University of Gothenburg, Box 410, 405 30 Gothenburg, Sweden; Beroendekliniken, Sahlgrenska University Hospital, Gothenburg, Sweden
| | - Louise Adermark
- Addiction Biology Unit, Department of Psychiatry and Neurochemistry, Institute of Neuroscience and Physiology, The Sahlgrenska Academy at the University of Gothenburg, Box 410, 405 30 Gothenburg, Sweden
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17
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Mitra S, Mucha M, Khatri SN, Glenon R, Schulte MK, Bult-Ito A. Attenuation of Compulsive-Like Behavior Through Positive Allosteric Modulation of α4β2 Nicotinic Acetylcholine Receptors in Non-Induced Compulsive-Like Mice. Front Behav Neurosci 2017; 10:244. [PMID: 28105008 PMCID: PMC5214813 DOI: 10.3389/fnbeh.2016.00244] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2016] [Accepted: 12/14/2016] [Indexed: 11/23/2022] Open
Abstract
Nicotinic α4β2 receptors are the most abundant subtypes of nicotinic acetylcholine receptors (nAChRs) expressed in brain regions implicated in obsessive compulsive disorder (OCD). These receptors are known to modify normal and addictive behaviors by modulating neuronal excitability. Desformylflustrabromine (dFBr) is a novel, positive allosteric modulator (PAM) of high acetylcholine sensitivity (HS) and low acetylcholine sensitivity (LS) α4β2 nAChRs. The present study tested the hypothesis that positive allosteric modulation of α4β2 receptors by dFBr will attenuate compulsive-like behavior in a non-induced compulsive-like mouse model. Male mice (Mus musculus) selected for compulsive-like nesting behavior (NB; 48 animals; 12 per group) received acute (once) and chronic (every day for 32 days) subcutaneous injection of dFBr at 2, 4 and 6 mg/kg doses. Saline was used as a control (0 mg/kg). Compulsive-like NB was assessed after 1, 2, 3, 4, 5 and 24 h, while compulsive-like marble burying (MB) and anxiety-like open field (OF) behaviors were performed 2 h after dFBr administration. In the acute administration protocol, dFBr dose dependently attenuated NB and MB. Rapid effects (1–2 h after drug administration) of dFBr on MB and NB were observed for the chronic administration which was in congruence with the acute study. Chronic administration also revealed sustained suppression of NB by dFBr following 5 weeks of treatment. In both the acute and chronic regimen dFBr did not modulate OF behaviors. This research demonstrates the novel role of positive allosteric modulation of α4β2 nicotinic receptors by dFBr as a translational potential for OCD.
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Affiliation(s)
- Swarup Mitra
- Department of Chemistry and Biochemistry, University of Alaska FairbanksFairbanks, AK, USA; IDeA Network of Biomedical Research Excellence (INBRE), University of Alaska FairbanksFairbanks, AK, USA
| | - Mckenzie Mucha
- Department of Chemistry and Biochemistry, University of Alaska Fairbanks Fairbanks, AK, USA
| | - Shailesh N Khatri
- Department of Pharmaceutical Sciences, Philadelphia College of Pharmacy, University of the Sciences Philadelphia, PA, USA
| | - Richard Glenon
- Department of Medicinal Chemistry, School of Pharmacy, Virginia Commonwealth University Richmond, VA, USA
| | - Marvin K Schulte
- Department of Pharmaceutical Sciences, Philadelphia College of Pharmacy, University of the Sciences Philadelphia, PA, USA
| | - Abel Bult-Ito
- Department of Biology and Wildlife, University of Alaska Fairbanks Fairbanks, AK, USA
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18
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Chung BYT, Bignell W, Jacklin DL, Winters BD, Bailey CDC. Postsynaptic nicotinic acetylcholine receptors facilitate excitation of developing CA1 pyramidal neurons. J Neurophysiol 2016; 116:2043-2055. [PMID: 27489367 DOI: 10.1152/jn.00370.2016] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2016] [Accepted: 08/01/2016] [Indexed: 11/22/2022] Open
Abstract
The hippocampus plays a key role in learning and memory. The normal development and mature function of hippocampal networks supporting these cognitive functions depends on afferent cholinergic neurotransmission mediated by nicotinic acetylcholine receptors. Whereas it is well-established that nicotinic receptors are present on GABAergic interneurons and on glutamatergic presynaptic terminals within the hippocampus, the ability of these receptors to mediate postsynaptic signaling in pyramidal neurons is not well understood. We use whole cell electrophysiology to show that heteromeric nicotinic receptors mediate direct inward currents, depolarization from rest and enhanced excitability in hippocampus CA1 pyramidal neurons of male mice. Measurements made throughout postnatal development provide a thorough developmental profile for these heteromeric nicotinic responses, which are greatest during the first 2 wk of postnatal life and decrease to low adult levels shortly thereafter. Pharmacological experiments show that responses are blocked by a competitive antagonist of α4β2* nicotinic receptors and augmented by a positive allosteric modulator of α5 subunit-containing receptors, which is consistent with expression studies suggesting the presence of α4β2 and α4β2α5 nicotinic receptors within the developing CA1 pyramidal cell layer. These findings demonstrate that functional heteromeric nicotinic receptors are present on CA1 pyramidal neurons during a period of major hippocampal development, placing these receptors in a prime position to play an important role in the establishment of hippocampal cognitive networks.
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Affiliation(s)
- Beryl Y T Chung
- Department of Biomedical Sciences, Ontario Veterinary College, University of Guelph, Guelph, Ontario, Canada; and
| | - Warren Bignell
- Department of Biomedical Sciences, Ontario Veterinary College, University of Guelph, Guelph, Ontario, Canada; and
| | - Derek L Jacklin
- Department of Psychology, College of Social and Applied Human Sciences, University of Guelph, Guelph, Ontario, Canada
| | - Boyer D Winters
- Department of Psychology, College of Social and Applied Human Sciences, University of Guelph, Guelph, Ontario, Canada
| | - Craig D C Bailey
- Department of Biomedical Sciences, Ontario Veterinary College, University of Guelph, Guelph, Ontario, Canada; and
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19
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Carignano C, Barila EP, Spitzmaul G. Analysis of neuronal nicotinic acetylcholine receptor α4β2 activation at the single-channel level. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2016; 1858:1964-1973. [PMID: 27233449 DOI: 10.1016/j.bbamem.2016.05.019] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/07/2016] [Revised: 05/09/2016] [Accepted: 05/16/2016] [Indexed: 12/11/2022]
Abstract
The neuronal nicotinic acetylcholine receptor α4β2 forms pentameric proteins with two alternate stoichiometries. The high-sensitivity receptor is related to (α4)2(β2)3 stoichiometry while the low-sensitivity receptor to (α4)3(β2)2 stoichiometry. Both subtypes share two binding sites at the α4((+))/β2((-)) interface with high affinity for agonists. (α4)3(β2)2 has an additional binding site at the α4((+))/α4((-)) interface with low affinity for agonists. We investigated activation kinetics of both receptor subtypes by patch-clamp recordings of single-channel activity in the presence of several concentrations of acetylcholine (0.5 to 300μM). We used kinetic software to fit these data with kinetic models. We found that the high-sensitivity subtype correlates with the low-conductance channel (g-70=29pS) and does not activate with high efficacy. On the contrary, the low-sensitivity subtype correlated with a high-conductance channel (g-70=44pS) and exhibited higher activation efficacy. Opening events of individual nAChRs at high agonist concentrations occurred in clusters, which allowed us to determine kinetic constants for the activation of the triliganded receptor. Our kinetic modeling identified an intermediate state, between resting and open conformation of the receptor. Binding of the third molecule increases the efficacy of receptor activation by favoring the transition between resting and intermediate state around 18 times. The low rate for this transition in the diliganded receptor explains the action of acetylcholine as partial agonist when it binds to the high-affinity sites. The presence of the third binding site emerges as a potent modulator of nicotinic receptor α4β2 activation which may display different functions depending on agonist concentration.
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Affiliation(s)
- Camila Carignano
- Instituto de Investigaciones Bioquímicas de Bahía Blanca, Universidad Nacional del Sur-Consejo Nacional de Investigaciones Científicas y Técnicas, B8000FWB Bahía Blanca, Argentina
| | - Esteban Pablo Barila
- Instituto de Investigaciones Bioquímicas de Bahía Blanca, Universidad Nacional del Sur-Consejo Nacional de Investigaciones Científicas y Técnicas, B8000FWB Bahía Blanca, Argentina
| | - Guillermo Spitzmaul
- Instituto de Investigaciones Bioquímicas de Bahía Blanca, Universidad Nacional del Sur-Consejo Nacional de Investigaciones Científicas y Técnicas, B8000FWB Bahía Blanca, Argentina.
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20
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Geerts H, Roberts P, Spiros A. Assessing the synergy between cholinomimetics and memantine as augmentation therapy in cognitive impairment in schizophrenia. A virtual human patient trial using quantitative systems pharmacology. Front Pharmacol 2015; 6:198. [PMID: 26441655 PMCID: PMC4585031 DOI: 10.3389/fphar.2015.00198] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2015] [Accepted: 08/31/2015] [Indexed: 11/30/2022] Open
Abstract
While many drug discovery research programs aim to develop highly selective clinical candidates, their clinical success is limited because of the complex non-linear interactions of human brain neuronal circuits. Therefore, a rational approach for identifying appropriate synergistic multipharmacology and validating optimal target combinations is desperately needed. A mechanism-based Quantitative Systems Pharmacology (QSP) computer-based modeling platform that combines biophysically realistic preclinical neurophysiology and neuropharmacology with clinical information is a possible solution. This paper reports the application of such a model for Cognitive Impairment In Schizophrenia (CIAS), where the cholinomimetics galantamine and donepezil are combined with memantine and with different antipsychotics and smoking in a virtual human patient experiment. The results suggest that cholinomimetics added to antipsychotics have a modest effect on cognition in CIAS in non-smoking patients with haloperidol and risperidone and to a lesser extent with olanzapine and aripiprazole. Smoking reduces the effect of cholinomimetics with aripiprazole and olanzapine, but enhances the effect in haloperidol and risperidone. Adding memantine to antipsychotics improves cognition except with quetiapine, an effect enhanced with smoking. Combining cholinomimetics, antipsychotics and memantine in general shows an additive effect, except for a negative interaction with aripiprazole and quetiapine and a synergistic effect with olanzapine and haloperidol in non-smokers and haloperidol in smokers. The complex interaction of cholinomimetics with memantine, antipsychotics and smoking can be quantitatively studied using mechanism-based advanced computer modeling. QSP modeling of virtual human patients can possibly generate useful insights on the non-linear interactions of multipharmacology drugs and support complex CNS R&D projects in cognition in search of synergistic polypharmacy.
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Affiliation(s)
- Hugo Geerts
- In Silico Biosciences Berwyn, PA, USA ; Perelman School of Medicine, University of Pennsylvania Philadelphia, PA, USA
| | - Patrick Roberts
- Department of Veterinary and Comparative Anatomy, Pharmacology and Physiology, Washington State University Pullman, WA, USA
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21
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Henderson BJ, Lester HA. Inside-out neuropharmacology of nicotinic drugs. Neuropharmacology 2015; 96:178-93. [PMID: 25660637 DOI: 10.1016/j.neuropharm.2015.01.022] [Citation(s) in RCA: 72] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2014] [Revised: 01/20/2015] [Accepted: 01/20/2015] [Indexed: 02/05/2023]
Abstract
Upregulation of neuronal nicotinic acetylcholine receptors (AChRs) is a venerable result of chronic exposure to nicotine; but it is one of several consequences of pharmacological chaperoning by nicotine and by some other nicotinic ligands, especially agonists. Nicotinic ligands permeate through cell membranes, bind to immature AChR oligomers, elicit incompletely understood conformational reorganizations, increase the interaction between adjacent AChR subunits, and enhance the maturation process toward stable AChR pentamers. These changes and stabilizations in turn lead to increases in both anterograde and retrograde traffic within the early secretory pathway. In addition to the eventual upregulation of AChRs at the plasma membrane, other effects of pharmacological chaperoning include modifications to endoplasmic reticulum stress and to the unfolded protein response. Because these processes depend on pharmacological chaperoning within intracellular organelles, we group them as "inside-out pharmacology". This term contrasts with the better-known, acute, "outside-in" effects of activating and desensitizing plasma membrane AChRs. We review current knowledge concerning the mechanisms and consequences of inside-out pharmacology. This article is part of the Special Issue entitled 'The Nicotinic Acetylcholine Receptor: From Molecular Biology to Cognition'.
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Affiliation(s)
- Brandon J Henderson
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| | - Henry A Lester
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA.
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Grupe M, Grunnet M, Bastlund JF, Jensen AA. Targeting α4β2 Nicotinic Acetylcholine Receptors in Central Nervous System Disorders: Perspectives on Positive Allosteric Modulation as a Therapeutic Approach. Basic Clin Pharmacol Toxicol 2014; 116:187-200. [DOI: 10.1111/bcpt.12361] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2014] [Accepted: 11/24/2014] [Indexed: 12/11/2022]
Affiliation(s)
- Morten Grupe
- Synaptic Transmission; H. Lundbeck A/S; Valby Denmark
| | - Morten Grunnet
- Synaptic Transmission; H. Lundbeck A/S; Valby Denmark
- Department of Drug Design and Pharmacology; Faculty of Health and Medical Sciences; University of Copenhagen; Copenhagen Denmark
| | | | - Anders A. Jensen
- Department of Drug Design and Pharmacology; Faculty of Health and Medical Sciences; University of Copenhagen; Copenhagen Denmark
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23
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Hernández-Vázquez F, Chavarría K, Garduño J, Hernández-López S, Mihailescu SP. Nicotine increases GABAergic input on rat dorsal raphe serotonergic neurons through alpha7 nicotinic acetylcholine receptor. J Neurophysiol 2014; 112:3154-63. [DOI: 10.1152/jn.00223.2014] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The dorsal raphe nucleus (DRN) contains large populations of serotonergic (5-HT) neurons. This nucleus receives GABAergic inhibitory afferents from many brain areas and from DRN interneurons. Both GABAergic and 5-HT DRN neurons express functional nicotinic acetylcholine receptors (nAChRs). Previous studies have demonstrated that nicotine increases 5-HT release and 5-HT DRN neuron discharge rate by stimulating postsynaptic nAChRs and by increasing glutamate and norepinephrine release inside DRN. However, the influence of nicotine on the GABAergic input to 5-HT DRN neurons was poorly investigated. Therefore, the aim of this work was to determine the effect of nicotine on GABAergic spontaneous inhibitory postsynaptic currents (sIPSCs) of 5-HT DRN neurons and the subtype of nAChR(s) involved in this response. Experiments were performed in coronal slices obtained from young Wistar rats. GABAergic sIPSCs were recorded from post hoc-identified 5-HT DRN neurons with the whole cell voltage patch-clamp technique. Administration of nicotine (1 μM) increased sIPSC frequency in 72% of identified 5-HT DRN neurons. This effect was not reproduced by the α4β2 nAChR agonist RJR-2403 and was not influenced by TTX (1 μM). It was mimicked by the selective agonist for α7 nAChR, PNU-282987, and exacerbated by the positive allosteric modulator of the same receptor, PNU-120596. The nicotine-induced increase in sIPSC frequency was independent on voltage-gated calcium channels and dependent on Ca2+-induced Ca2+ release (CICR). These results demonstrate that nicotine increases the GABAergic input to most 5-HT DRN neurons, by activating α7 nAChRs and producing CICR in DRN GABAergic terminals.
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Affiliation(s)
- F. Hernández-Vázquez
- Departamento de Fisiología, Facultad de Medicina, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - K. Chavarría
- Departamento de Fisiología, Facultad de Medicina, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - J. Garduño
- Departamento de Fisiología, Facultad de Medicina, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - S. Hernández-López
- Departamento de Fisiología, Facultad de Medicina, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - S. P. Mihailescu
- Departamento de Fisiología, Facultad de Medicina, Universidad Nacional Autónoma de México, Mexico City, Mexico
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24
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Valencia A, Sapp E, Kimm JS, McClory H, Ansong KA, Yohrling G, Kwak S, Kegel KB, Green KM, Shaffer SA, Aronin N, DiFiglia M. Striatal synaptosomes from Hdh140Q/140Q knock-in mice have altered protein levels, novel sites of methionine oxidation, and excess glutamate release after stimulation. J Huntingtons Dis 2014; 2:459-75. [PMID: 24696705 DOI: 10.3233/jhd-130080] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
BACKGROUND Synaptic connections are disrupted in patients with Huntington's disease (HD). Synaptosomes from postmortem brain are ideal for synaptic function studies because they are enriched in pre- and post-synaptic proteins important in vesicle fusion, vesicle release, and neurotransmitter receptor activation. OBJECTIVE To examine striatal synaptosomes from 3, 6 and 12 month old WT and Hdh140Q/140Q knock-in mice for levels of synaptic proteins, methionine oxidation, and glutamate release. METHODS We used Western blot analysis, glutamate release assays, and liquid chromatography tandem mass spectrometry (LC-MS/MS). RESULTS Striatal synaptosomes of 6 month old Hdh140Q/140Q mice had less DARPP32, syntaxin 1 and calmodulin compared to WT. Striatal synaptosomes of 12 month old Hdh140Q/140Q mice had lower levels of DARPP32, alpha actinin, HAP40, Na+/K+-ATPase, PSD95, SNAP-25, TrkA and VAMP1, VGlut1 and VGlut2, increased levels of VAMP2, and modifications in actin and calmodulin compared to WT. More glutamate released from vesicles of depolarized striatal synaptosomes of 6 month old Hdh140Q/140Q than from age matched WT mice but there was no difference in glutamate release in synaptosomes of 3 and 12 month old WT and Hdh140Q/140Q mice. LC-MS/MS of 6 month old Hdh140Q/140Q mice striatal synaptosomes revealed that about 4% of total proteins detected (>600 detected) had novel sites of methionine oxidation including proteins involved with vesicle fusion, trafficking, and neurotransmitter function (synaptophysin, synapsin 2, syntaxin 1, calmodulin, cytoplasmic actin 2, neurofilament, and tubulin). Altered protein levels and novel methionine oxidations were also seen in cortical synaptosomes of 12 month old Hdh140Q/140Q mice. CONCLUSIONS Findings provide support for early synaptic dysfunction in Hdh140Q/140Q knock-in mice arising from altered protein levels, oxidative damage, and impaired glutamate neurotransmission and suggest that study of synaptosomes could be of value for evaluating HD therapies.
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25
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McClure-Begley TD, Grady SR, Marks MJ, Collins AC, Stitzel JA. Presynaptic GABAB autoreceptor regulation of nicotinic acetylcholine receptor mediated [(3)H]-GABA release from mouse synaptosomes. Biochem Pharmacol 2014; 91:87-96. [PMID: 24953818 DOI: 10.1016/j.bcp.2014.06.010] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2014] [Revised: 06/06/2014] [Accepted: 06/12/2014] [Indexed: 01/26/2023]
Abstract
Activation of nicotinic acetylcholine receptors (nAChRs) can elicit neurotransmitter release from presynaptic nerve terminals. Mechanisms contributing to cell-and-terminal specific regulation of nAChR-mediated neurotransmitter exocytosis are not fully understood. The experiments discussed here examine how activation of GABAB auto- and hetero-receptors suppress nAChR-mediated release of [(3)H]-GABA and [(3)H]-dopamine ((3)H-DA) from mouse striatal synaptosomes. Activation of presynaptic GABAB receptors with (R)-baclofen decreased both [(3)H]-GABA and [(3)H]-DA release evoked by potassium depolarization. However, when nAChRs were activated with ACh to evoke neurotransmitter release, (R)-baclofen had no effect on [(3)H]-DA release, but potently inhibited ACh-evoked [(3)H]-GABA release. Inhibition of nAChR-evoked [(3)H]-GABA release by (R)-baclofen was time sensitive and the effect was lost after prolonged exposure to the GABAB agonist. The early inhibitory effect of GABAB activation on ACh-evoked [(3)H]-GABA release was partially attenuated by antagonists of the phosphatase, calcineurin. Furthermore, antagonists of protein kinase C (PKC) prevented the time-dependent loss of the inhibitory (R)-baclofen effect on [(3)H]-GABA release. These results suggest that α4β2*-nAChRs present on GABAergic nerve terminals in the striatum are subject to functional regulation by GABAB autoreceptors that is apparently cell-type specific, since it is absent from DAergic striatal nerve terminals. In addition, the functional modulation of α4β2*-type nAChRs on striatal GABAergic nerve terminals by GABAB autoreceptor activation is time-sensitive and appears to involve opposing actions of calcineurin and PKC.
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Affiliation(s)
- Tristan D McClure-Begley
- Institute for Behavioral Genetics, University of Colorado, Boulder, CO, United States of America; Department of Integrative Physiology, University of Colorado, Boulder, CO, United States of America; Department of Molecular, Cellular and Developmental Biology, University of Colorado, Boulder, CO, United States of America
| | - Sharon R Grady
- Institute for Behavioral Genetics, University of Colorado, Boulder, CO, United States of America
| | - Michael J Marks
- Institute for Behavioral Genetics, University of Colorado, Boulder, CO, United States of America; Department of Psychology and Neuroscience, University of Colorado, Boulder, CO, United States of America
| | - Allan C Collins
- Institute for Behavioral Genetics, University of Colorado, Boulder, CO, United States of America
| | - Jerry A Stitzel
- Institute for Behavioral Genetics, University of Colorado, Boulder, CO, United States of America; Department of Integrative Physiology, University of Colorado, Boulder, CO, United States of America.
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26
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Damborsky JC, Griffith WH, Winzer-Serhan UH. Neonatal nicotine exposure increases excitatory synaptic transmission and attenuates nicotine-stimulated GABA release in the adult rat hippocampus. Neuropharmacology 2014; 88:187-98. [PMID: 24950455 DOI: 10.1016/j.neuropharm.2014.06.010] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2013] [Revised: 06/02/2014] [Accepted: 06/09/2014] [Indexed: 01/22/2023]
Abstract
Developmental exposure to nicotine has been linked to long-lasting changes in synaptic transmission which may contribute to behavioral abnormalities seen in offspring of women who smoke during pregnancy. Here, we examined the long-lasting effects of developmental nicotine exposure on glutamatergic and GABAergic neurotransmission, and on acute nicotine-induced glutamate and GABA release in the adult hippocampus, a structure important in cognitive and emotional behaviors. We utilized a chronic neonatal nicotine treatment model to administer nicotine (6 mg/kg/day) to rat pups from postnatal day (P) 1-7, a period that falls developmentally into the third human trimester. Using whole-cell voltage clamp recordings from CA1 pyramidal neurons in hippocampal slices, we measured excitatory and inhibitory postsynaptic currents in neonatally control- and nicotine-treated young adult males. Neonatal nicotine exposure significantly increased AMPA receptor-mediated spontaneous and evoked excitatory signaling, with no change in glutamate release probability in adults. Conversely, there was no increase in spontaneous GABAergic neurotransmission in nicotine-males. Chronic neonatal nicotine treatment had no effect on acute nicotine-stimulated glutamate release in adults, but acute nicotine-stimulated GABA release was significantly attenuated. Thus, neonatal nicotine exposure results in a persistent net increase in excitation and a concurrent loss of nicotinic acetylcholine receptor (nAChR)-mediated regulation of presynaptic GABA but not glutamate release, which would exacerbate excitation following endogenous or exogenous nAChR activation. Our data underscore an important role for nAChRs in hippocampal excitatory synapse development, and suggest selective long-term changes at specific presynaptic nAChRs which together could explain some of the behavioral abnormalities associated with maternal smoking.
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Affiliation(s)
- Joanne C Damborsky
- Department of Neuroscience & Experimental Therapeutics, College of Medicine, Health Science Center, Texas A&M University, USA
| | - William H Griffith
- Department of Neuroscience & Experimental Therapeutics, College of Medicine, Health Science Center, Texas A&M University, USA
| | - Ursula H Winzer-Serhan
- Department of Neuroscience & Experimental Therapeutics, College of Medicine, Health Science Center, Texas A&M University, USA.
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27
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Nicotinic acetylcholine receptors in attention circuitry: the role of layer VI neurons of prefrontal cortex. Cell Mol Life Sci 2014; 71:1225-44. [PMID: 24122021 PMCID: PMC3949016 DOI: 10.1007/s00018-013-1481-3] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2013] [Revised: 09/03/2013] [Accepted: 09/16/2013] [Indexed: 12/15/2022]
Abstract
Cholinergic modulation of prefrontal cortex is essential for attention. In essence, it focuses the mind on relevant, transient stimuli in support of goal-directed behavior. The excitation of prefrontal layer VI neurons through nicotinic acetylcholine receptors optimizes local and top-down control of attention. Layer VI of prefrontal cortex is the origin of a dense feedback projection to the thalamus and is one of only a handful of brain regions that express the α5 nicotinic receptor subunit, encoded by the gene chrna5. This accessory nicotinic receptor subunit alters the properties of high-affinity nicotinic receptors in layer VI pyramidal neurons in both development and adulthood. Studies investigating the consequences of genetic deletion of α5, as well as other disruptions to nicotinic receptors, find attention deficits together with altered cholinergic excitation of layer VI neurons and aberrant neuronal morphology. Nicotinic receptors in prefrontal layer VI neurons play an essential role in focusing attention under challenging circumstances. In this regard, they do not act in isolation, but rather in concert with cholinergic receptors in other parts of prefrontal circuitry. This review urges an intensification of focus on the cellular mechanisms and plasticity of prefrontal attention circuitry. Disruptions in attention are one of the greatest contributing factors to disease burden in psychiatric and neurological disorders, and enhancing attention may require different approaches in the normal and disordered prefrontal cortex.
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28
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Subsynaptic localization of nicotinic acetylcholine receptor subunits: A comparative study in the mouse and rat striatum. Neurosci Lett 2014; 566:106-10. [DOI: 10.1016/j.neulet.2014.02.018] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2013] [Revised: 02/05/2014] [Accepted: 02/09/2014] [Indexed: 11/20/2022]
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29
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Varani AP, Antonelli MC, Balerio GN. Mecamylamine-precipitated nicotine withdrawal syndrome and its prevention with baclofen: an autoradiographic study of α4β2 nicotinic acetylcholine receptors in mice. Prog Neuropsychopharmacol Biol Psychiatry 2013; 44:217-25. [PMID: 23500668 DOI: 10.1016/j.pnpbp.2013.02.016] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/11/2012] [Revised: 02/13/2013] [Accepted: 02/27/2013] [Indexed: 11/26/2022]
Abstract
A previous study from our laboratory showed that baclofen (BAC, GABAB receptor agonist) was able to prevent the behavioral expression of nicotine (NIC) withdrawal syndrome. To further investigate the mechanisms underlying this effect, we conducted this study, with the aims of analyzing α4β2 nicotinic receptor density during NIC withdrawal and, in case we found any changes, of determining whether they could be prevented by pretreatment with BAC. Swiss Webster albino mice received NIC (2.5 mg/kg, s.c.) 4 times daily, for 7 days. On the 8th day, NIC-treated mice received the nicotinic antagonist mecamylamine (MEC; 2 mg/kg, i.p.) 1 h after the last dose of NIC. A second group of NIC-treated mice received BAC (2 mg/kg, i.p.) prior to MEC administration. Thirty minutes after MEC, mice were sacrificed and brain autoradiography with [(3)H]epibatidine was carried out at five different anatomical levels. Autoradiographic mapping showed a significant increase of α4β2 nicotinic receptor labeling during NIC withdrawal in the nucleus accumbens shell (AcbSh), medial habenular nucleus (HbM), thalamic nuclei, dorsal lateral geniculate (DLG) nucleus, fasciculus retroflexus (fr), ventral tegmental area, interpeduncular nucleus and superior colliculus. BAC pretreatment prevented the increased α4β2 nicotinic receptor binding sites in the AcbSh, MHb, thalamic nuclei, DLG nucleus and fr. The present results suggest a relationship between BAC's preventive effect of the expression of NIC withdrawal signs, and its ability to restore the changes in α4β2 nicotinic receptor labeling, evidenced in specific brain areas in NIC withdrawn animals.
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Affiliation(s)
- Andrés P Varani
- Instituto de Investigaciones Farmacológicas (UBA-CONICET), Junín 956, 5° Piso, C1113AAD, Buenos Aires, Argentina
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30
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Powers MS, Broderick HJ, Drenan RM, Chester JA. Nicotinic acetylcholine receptors containing α6 subunits contribute to alcohol reward-related behaviours. GENES BRAIN AND BEHAVIOR 2013; 12:543-53. [PMID: 23594044 DOI: 10.1111/gbb.12042] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/09/2013] [Revised: 03/14/2013] [Accepted: 04/08/2013] [Indexed: 12/20/2022]
Abstract
Evidence is emerging that neuronal nicotinic acetylcholine receptors (nAChRs) in the mesolimbic dopamine (DA) system are involved in mediating the reinforcing effects of alcohol. Midbrain DA neurons express high levels of α6 subunit-containing nAChRs that modulate DA transmission, implicating their involvement in reward-related behaviours. This study assessed the role of α6-containing nAChRs in modulating alcohol reward using transgenic mice expressing mutant, hypersensitive α6 nAChR subunits (α6L9'S mice). α6L9'S mice and littermate controls were tested in three well-established models of alcohol reward: 24-h two-bottle choice drinking, drinking in the dark (DID), and conditioned place preference (CPP). Confocal microscopy and patch-clamp electrophysiology were used to show the localization and function of hypersensitive α6 subunit-containing nAChRs. Results indicate that female α6L9'S mice showed significantly higher alcohol intake at low concentrations of alcohol (3% and 6%) in the two-bottle choice procedure. Both male and female α6L9'S mice drank significantly more in the DID procedure and displayed an alcohol-induced place preference using a low dose of alcohol (0.5 g/kg) that was ineffective in littermate controls. Confocal microscopy showed that α6 subunit-containing nAChRs are selectively expressed on ventral tegmental area (VTA) DAergic, but not GABAergic neurons. Patch-clamp electrophysiology showed that VTA DA neurons of α6L9'S mice are hypersensitive to ACh. Collectively, these results suggest that α6L9'S mice are more sensitive to the rewarding effects of alcohol, and suggest that VTA α6 subunit-containing nAChRs modulate alcohol reward. Thus, α6 subunit-containing nAChRs may be a promising therapeutic target for treatment of alcohol use disorders.
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Affiliation(s)
- M S Powers
- Department of Psychological Sciences, Purdue University, West Lafayette,IN 47907, USA
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31
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Liu Q, Emadi S, Shen JX, Sierks MR, Wu J. Human α4β2 nicotinic acetylcholine receptor as a novel target of oligomeric α-synuclein. PLoS One 2013; 8:e55886. [PMID: 23437071 PMCID: PMC3577813 DOI: 10.1371/journal.pone.0055886] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2012] [Accepted: 01/07/2013] [Indexed: 12/22/2022] Open
Abstract
Cigarette smoking is associated with a decreased incidence of Parkinson disease (PD) through unknown mechanisms. Interestingly, a decrease in the numbers of α4β2 nicotinic acetylcholine receptors (α4β2-nAChRs) in PD patients suggests an α4β2-nAChR-mediated cholinergic deficit in PD. Although oligomeric forms of α-synuclein have been recognized to be toxic and involved in the pathogenesis of PD, their direct effects on nAChR-mediated cholinergic signaling remains undefined. Here, we report for the first time that oligomeric α-synuclein selectively inhibits human α4β2-nAChR-mediated currents in a dose-dependent, non-competitive and use-independent manner. We show that pre-loading cells with guanyl-5'-yl thiophosphate fails to prevent this inhibition, suggesting that the α-synuclein-induced inhibition of α4β2-nAChR function is not mediated by nAChR internalization. By using a pharmacological approach and cultures expressing transfected human nAChRs, we have shown a clear effect of oligomeric α-synuclein on α4β2-nAChRs, but not on α4β4- or α7-nAChRs, suggesting nAChR subunit selectivity of oligomeric α-synuclein-induced inhibition. In addition, by combining the size exclusion chromatography and atomic force microscopy (AFM) analyses, we find that only large (>4 nm) oligomeric α-synuclein aggregates (but not monomeric, small oligomeric or fibrillar α-synuclein aggregates) exhibit the inhibitory effect on human α4β2-nAChRs. Collectively, we have provided direct evidence that α4β2-nAChR is a sensitive target to mediate oligomeric α-synuclein-induced modulation of cholinergic signaling, and our data imply that therapeutic strategies targeted toward α4β2-nAChRs may have potential for developing new treatments for PD.
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Affiliation(s)
- Qiang Liu
- Divisions of Neurology, Barrow Neurological Institute, St. Joseph’s Hospital and Medical Center, Phoenix, Arizona, United States of America
| | - Sharareh Emadi
- Department of Chemical Engineering, Arizona State University, Tempe, Arizona, United States of America
| | - Jian-Xin Shen
- Department of Physiology, Shantou University of Medical College, Shantou, People’s Republic of China
| | - Michael R. Sierks
- Department of Chemical Engineering, Arizona State University, Tempe, Arizona, United States of America
| | - Jie Wu
- Divisions of Neurology, Barrow Neurological Institute, St. Joseph’s Hospital and Medical Center, Phoenix, Arizona, United States of America
- Department of Physiology, Shantou University of Medical College, Shantou, People’s Republic of China
- Department of Basic Medical Sciences, University of Arizona College of Medicine Phoenix, Arizona, United States of America
- * E-mail:
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32
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DuBois DW, Damborsky JC, Fincher AS, Frye GD, Winzer-Serhan UH. Varenicline and nicotine enhance GABAergic synaptic transmission in rat CA1 hippocampal and medial septum/diagonal band neurons. Life Sci 2013; 92:337-44. [PMID: 23352971 DOI: 10.1016/j.lfs.2012.12.013] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2012] [Revised: 12/18/2012] [Accepted: 12/26/2012] [Indexed: 11/16/2022]
Abstract
AIMS The FDA approved smoking cessation aid varenicline can effectively attenuate nicotine-stimulated dopamine release. Varenicline may also exert important actions on other transmitter systems that also influence nicotine reinforcement or contribute to the drug's cognitive and affective side effects. In this study, we determined if varenicline, like nicotine, can stimulate presynaptic GABA release. MAIN METHODS Using whole-cell patch-clamp techniques, we measured GABA(A)R-mediated asynchronous, spontaneous miniature inhibitory postsynaptic currents (mIPSCs) in acute brain slices from two brain regions important for learning and memory, the hippocampus and basal forebrain. KEY FINDINGS Both varenicline (10 μM) and nicotine (10 μM) applications alone resulted in small but significant increases in amplitude, as well as robustly enhanced frequency of mIPSCs in hippocampal CA1 pyramidal neurons and medial septum/diagonal band (MS/DB) neurons. A unique subpopulation of MS/DB neurons showed decreases in frequency. In the presence of nicotine, varenicline effectively attenuated the expected enhancement of hippocampal mIPSC frequency like a competitive antagonist. However, in the MS/DB, varenicline only partially attenuated nicotine's effects. Reversing the order of drug application by adding nicotine to varenicline-exposed slices had little effect. SIGNIFICANCE Varenicline, like nicotine, stimulates presynaptic GABA release, and also exerts a partial agonist action by attenuating nicotine-stimulated release in both the hippocampus and basal forebrain. These effects could potentially affect cognitive functions.
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Affiliation(s)
- Dustin W DuBois
- Department of Neuroscience & Experimental Therapeutics, College of Medicine, Texas A&M System Health Science Center, Bryan, TX 77807, USA
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Mice expressing the ADNFLE valine 287 leucine mutation of the Β2 nicotinic acetylcholine receptor subunit display increased sensitivity to acute nicotine administration and altered presynaptic nicotinic receptor function. Pharmacol Biochem Behav 2012; 103:603-21. [PMID: 23123803 DOI: 10.1016/j.pbb.2012.10.014] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/25/2012] [Revised: 09/26/2012] [Accepted: 10/24/2012] [Indexed: 01/16/2023]
Abstract
Several mutations in α4 or β2 nicotinic receptor subunits are linked to autosomal dominant nocturnal frontal lobe epilepsy (ADNFLE). One such missense mutation in the gene encoding the β2 neuronal nicotinic acetylcholine receptor (nAChR) subunit (CHRNB2) is a valine-to-leucine substitution in the second transmembrane domain at position 287 (β2VL). Previous studies indicated that the β2VL mutation in mice alters circadian rhythm consistent with sleep alterations observed in ADNFLE patients (Xu et al., 2011). The current study investigates changes in nicotinic receptor function and expression that may explain the behavioral phenotype of β2VL mice. No differences in β2 mRNA expression were found between wild-type (WT) and heterozygous (HT) or homozygous mutant (MT) mice. However, antibody and ligand binding indicated that the mutation resulted in a reduction in receptor protein. Functional consequences of the β2VL mutation were assessed biochemically using crude synaptosomes. A gene-dose dependent increase in sensitivity to activation by acetylcholine and decrease in maximal nAChR-mediated [(3)H]-dopamine release and (86)Rb efflux were observed. Maximal nAChR-mediated [(3)H]-GABA release in the cortex was also decreased in the MT, but maximal [(3)H]-GABA release was retained in the hippocampus. Behaviorally both HT and MT mice demonstrated increased sensitivity to nicotine-induced hypolocomotion and hypothermia. Furthermore, WT mice display only a tonic-clonic seizure (EEG recordable) 3 min after injection of a high dose of nicotine, while MT mice also display a dystonic arousal complex (non-EEG recordable) event 30s after nicotine injection. Data indicate decreases in maximal response for certain measures are larger than expected given the decrease in receptor expression.
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34
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α6* nicotinic acetylcholine receptor expression and function in a visual salience circuit. J Neurosci 2012; 32:10226-37. [PMID: 22836257 DOI: 10.1523/jneurosci.0007-12.2012] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Nicotinic acetylcholine receptors (nAChRs) containing α6 subunits are expressed in only a few brain areas, including midbrain dopamine (DA) neurons, noradrenergic neurons of the locus ceruleus, and retinal ganglion cells. To better understand the regional and subcellular expression pattern of α6-containing nAChRs, we created and studied transgenic mice expressing a variant α6 subunit with green fluorescent protein (GFP) fused in-frame in the M3-M4 intracellular loop. In α6-GFP transgenic mice, α6-dependent synaptosomal DA release and radioligand binding experiments confirmed correct expression and function in vivo. In addition to strong α6* nAChR expression in glutamatergic retinal axons, which terminate in superficial superior colliculus (sSC), we also found α6 subunit expression in a subset of GABAergic cell bodies in this brain area. In patch-clamp recordings from sSC neurons in brain slices from mice expressing hypersensitive α6* nAChRs, we confirmed functional, postsynaptic α6* nAChR expression. Further, sSC GABAergic neurons expressing α6* nAChRs exhibit a tonic conductance mediated by standing activation of hypersensitive α6* nAChRs by ACh. α6* nAChRs also appear in a subpopulation of SC neurons in output layers. Finally, selective activation of α6* nAChRs in vivo induced sSC neuronal activation as measured with c-Fos expression. Together, these results demonstrate that α6* nAChRs are uniquely situated to mediate cholinergic modulation of glutamate and GABA release in SC. The SC has emerged as a potential key brain area responsible for transmitting short-latency salience signals to thalamus and midbrain DA neurons, and these results suggest that α6* nAChRs may be important for nicotinic cholinergic sensitization of this pathway.
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35
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Radek RJ, Robb HM, Stevens KE, Gopalakrishnan M, Bitner RS. Effects of the novel α7 nicotinic acetylcholine receptor agonist ABT-107 on sensory gating in DBA/2 mice: pharmacodynamic characterization. J Pharmacol Exp Ther 2012; 343:736-45. [PMID: 22988063 DOI: 10.1124/jpet.112.197970] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Nicotinic acetylcholine receptor (nAChR) agonists improve sensory gating deficits in animal models and schizophrenic patients. The aim of this study was to determine whether the novel and selective α7 nAChR full agonist 5-(6-[(3R)-1-azabicyclo[2.2.2]oct-3-yloxy]pyridazin-3-yl)-1H-indole (ABT-107) improves sensory gating deficits in DBA/2 mice. Sensory gating was measured by recording hippocampal-evoked potential P20-N40 waves and determining gating test/conditioning (T/C) ratios in a paired auditory stimulus paradigm. ABT-107 at 0.1 μmol/kg (average plasma concentration of 1.1 ng/ml) significantly improved sensory gating by lowering T/C ratios during a 30-min period after administration in unanesthetized DBA/2 mice. ABT-107 at 1.0 μmol/kg was ineffective at 30 min after administration when average plasma levels were 13.5 ng/ml. However, the 1.0 μmol/kg dose was effective 180 min after administration when plasma concentration had fallen to 1.9 ng/ml. ABT-107 (0.1 μmol/kg) also improved sensory gating in anesthetized DBA/2 mice pretreated with α7 nAChR-desensitizing doses of nicotine (6.2 μmol/kg) or ABT-107 (0.1 μmol/kg) itself. Moreover, repeated b.i.d. dosing of ABT-107 (0.1 μmol/kg) was as efficacious as a single dose. The acute efficacy of ABT-107 (0.1 μmol/kg) was blocked by the nAChR antagonist methyllycaconitine, but not by the α4β2 nAChR antagonist dihydro-β-erythroidine. These studies demonstrate that ABT-107 improves sensory gating through the activation of nAChRs, and efficacy is sustained under conditions of repeated dosing or with prior nAChR activation with nicotine.
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Affiliation(s)
- Richard J Radek
- Global Pharmaceutical Research and Development, Abbott Laboratories, Abbott Park, IL 60064, USA.
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Drenan RM, Lester HA. Insights into the neurobiology of the nicotinic cholinergic system and nicotine addiction from mice expressing nicotinic receptors harboring gain-of-function mutations. Pharmacol Rev 2012; 64:869-79. [PMID: 22885704 DOI: 10.1124/pr.111.004671] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Nicotinic acetylcholine receptors (nAChRs) are ligand-gated, cation-selective ion channels expressed throughout the brain. Although these channels have been investigated for several decades, it is still challenging 1) to identify the important nAChR subunits in cholinergic transmission and nicotine dependence and 2) to develop nAChR subtype-specific ligands. To overcome these challenges, we and others have studied mice expressing mutant, gain-of-function nAChR subunits. In this review, we discuss this research approach and the results it has yielded to date. Gain-of-function mutations, including those in nAChR subunits, provide an approach that is complementary to loss-of-function studies such as gene knockouts; the former allows one to answer questions of sufficiency and the latter addresses questions of necessity. Mutant mice expressing gain-of-function nAChR subunits are commonly produced using traditional gene targeting in embryonic stem cells, but novel approaches such as bacterial artificial chromosome transgenesis have yielded important insights as well. α7 nAChRs were the first nAChRs to be targeted with a gain-of-function mutation, followed by a pair of α4 nAChR gain-of-function mutant mice. These α4 nAChR gain-of-function mice (α4 L9'S mice, followed by α4 L9'A mice) provided an important system to probe α4 nAChR function in vivo, particularly in the dopamine reward system. α6 nAChR gain-of-function mice provided the first robust system allowing specific manipulation of this receptor subtype. Other targeted mutations in various nAChR subunits have also been produced and have yielded important insights into nicotinic cholinergic biology. As nAChR research advances and more details associated with nAChR expression and function emerge, we expect that existing and new mouse lines expressing gain-of-function nAChR subunits will continue to provide new insights.
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Affiliation(s)
- Ryan M Drenan
- Purdue University, Department of Medicinal Chemistry and Molecular Pharmacology, West Lafayette, IN 47907, USA.
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Dobelis P, Staley KJ, Cooper DC. Lack of modulation of nicotinic acetylcholine alpha-7 receptor currents by kynurenic acid in adult hippocampal interneurons. PLoS One 2012; 7:e41108. [PMID: 22848433 PMCID: PMC3405093 DOI: 10.1371/journal.pone.0041108] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2012] [Accepted: 06/21/2012] [Indexed: 11/17/2022] Open
Abstract
Kynurenic acid (KYNA), a classical ionotropic glutamate receptor antagonist is also purported to block the α7-subtype nicotinic acetylcholine receptor (α7* nAChR). Although many published studies cite this potential effect, few have studied it directly. In this study, the α7*-selective agonist, choline, was pressure-applied to interneurons in hippocampal subregions, CA1 stratum radiatum and hilus of acute brain hippocampal slices from adolescent to adult mice and adolescent rats. Stable α7* mediated whole-cell currents were measured using voltage-clamp at physiological temperatures. The effects of bath applied KYNA on spontaneous glutamatergic excitatory postsynaptic potentials (sEPSC) as well as choline-evoked α7* currents were determined. In mouse hilar interneurons, KYNA totally blocked sEPSC whole-cell currents in a rapid and reversible manner, but had no effect on choline-evoked α7* whole-cell currents. To determine if this lack of KYNA effect on α7* function was due to regional and/or species differences in α7* nAChRs, the effects of KYNA on choline-evoked α7* whole-cell currents in mouse and rat stratum radiatum interneurons were tested. KYNA had no effect on either mouse or rat stratum radiatum interneuron choline-evoked α7* whole-cell currents. Finally, to test whether the lack of effect of KYNA was due to unlikely slow kinetics of KYNA interactions with α7* nAChRs, recordings of a7*-mediated currents were made from slices that were prepared and stored in the presence of 1 mM KYNA (>90 minutes exposure). Under these conditions, KYNA had no measurable effect on α7* nAChR function. The results show that despite KYNA-mediated blockade of glutamatergic sEPSCs, two types of hippocampal interneurons that express choline-evoked α7* nAChR currents fail to show any degree of modulation by KYNA. Our results indicate that under our experimental conditions, which produced complete KYNA-mediated blockade of sEPSCs, claims of KYNA effects on choline-evoked α7* nAChR function should be made with caution.
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Affiliation(s)
- Peter Dobelis
- Center for Neuroscience, Institute for Behavioral Genetics, Department of Neuroscience, University of Colorado at Boulder, Boulder, Colorado, United States of America
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Grilli M, Summa M, Salamone A, Olivero G, Zappettini S, Di Prisco S, Feligioni M, Usai C, Pittaluga A, Marchi M. In vitro exposure to nicotine induces endocytosis of presynaptic AMPA receptors modulating dopamine release in rat nucleus accumbens nerve terminals. Neuropharmacology 2012; 63:916-26. [PMID: 22771975 DOI: 10.1016/j.neuropharm.2012.06.049] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2011] [Revised: 06/19/2012] [Accepted: 06/24/2012] [Indexed: 01/02/2023]
Abstract
Here we provide functional and immunocytochemical evidence supporting the presence on Nucleus Accumbens (NAc) dopaminergic terminals of cyclothiazide-sensitive, alfa-amino-3-hydroxy-5-methyl-4-isoxazolone propionate (AMPA) receptors, which activation causes Ca²⁺-dependent [³H]dopamine ([³H]DA) exocytosis. These AMPA receptors cross-talk with co-localized nicotinic receptors (nAChRs), as suggested by the finding that in vitro short-term pre-exposure of synaptosomes to 30 μM nicotine caused a significant reduction of both the 30 μM nicotine and the 100 μM AMPA-evoked [³H]DA overflow. Entrapping pep2-SVKI, a peptide known to compete for the binding of GluA2 subunit to scaffolding proteins involved in AMPA receptor endocytosis, in NAC synaptosomes prevented the nicotine-induced reduction of AMPA-mediated [³H]DA exocytosis, while pep2-SVKE, used as negative control, was inefficacious. Immunocytochemical studies showed that a significant percentage of NAc terminals were dopaminergic and that most of these terminals also posses GluA2 receptor subunits. Western blot analysis of GluA2 immunoreactivity showed that presynaptic GluA2 proteins in NAc terminals were reduced in nicotine-pretreated synaptosomes when compared to the control. The nACh-AMPA receptor-receptor interaction was not limited to dopaminergic terminals since nicotine pre-exposure also affected the presynaptic AMPA receptors controlling hippocampal noradrenaline release, but not the presynaptic AMPA receptors controlling GABA and acetylcholine release. These observations could be relevant to the comprehension of the molecular mechanisms at the basis of nicotine rewarding.
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Affiliation(s)
- Massimo Grilli
- Department of Experimental Medicine, Pharmacology and Toxicology Section, University of Genoa, Viale Cembrano 4, 16148 Genoa, Italy
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Quik M, Wonnacott S. α6β2* and α4β2* nicotinic acetylcholine receptors as drug targets for Parkinson's disease. Pharmacol Rev 2012; 63:938-66. [PMID: 21969327 DOI: 10.1124/pr.110.003269] [Citation(s) in RCA: 147] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Parkinson's disease is a debilitating movement disorder characterized by a generalized dysfunction of the nervous system, with a particularly prominent decline in the nigrostriatal dopaminergic pathway. Although there is currently no cure, drugs targeting the dopaminergic system provide major symptomatic relief. As well, agents directed to other neurotransmitter systems are of therapeutic benefit. Such drugs may act by directly improving functional deficits in these other systems, or they may restore aberrant motor activity that arises as a result of a dopaminergic imbalance. Recent research attention has focused on a role for drugs targeting the nicotinic cholinergic systems. The rationale for such work stems from basic research findings that there is an extensive overlap in the organization and function of the nicotinic cholinergic and dopaminergic systems in the basal ganglia. In addition, nicotinic acetylcholine receptor (nAChR) drugs could have clinical potential for Parkinson's disease. Evidence for this proposition stems from studies with experimental animal models showing that nicotine protects against neurotoxin-induced nigrostriatal damage and improves motor complications associated with l-DOPA, the "gold standard" for Parkinson's disease treatment. Nicotine interacts with multiple central nervous system receptors to generate therapeutic responses but also produces side effects. It is important therefore to identify the nAChR subtypes most beneficial for treating Parkinson's disease. Here we review nAChRs with particular emphasis on the subtypes that contribute to basal ganglia function. Accumulating evidence suggests that drugs targeting α6β2* and α4β2* nAChR may prove useful in the management of Parkinson's disease.
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Affiliation(s)
- Maryka Quik
- Center for Health Sciences, SRI International, Menlo Park, CA 94025, USA.
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McClure-Begley TD, Wageman CR, Grady SR, Marks MJ, McIntosh JM, Collins AC, Whiteaker P. A novel α-conotoxin MII-sensitive nicotinic acetylcholine receptor modulates [(3) H]-GABA release in the superficial layers of the mouse superior colliculus. J Neurochem 2012; 122:48-57. [PMID: 22506481 DOI: 10.1111/j.1471-4159.2012.07759.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Mouse superficial superior colliculus (SuSC) contains dense GABAergic innervation and diverse nicotinic acetylcholine receptor subtypes. Pharmacological and genetic approaches were used to investigate the subunit compositions of nicotinic acetylcholine receptors (nAChR) expressed on mouse SuSC GABAergic terminals. [(125) I]-Epibatidine competition-binding studies revealed that the α3β2* and α6β2* nicotinic subtype-selective peptide α-conotoxin MII-blocked binding to 40 ± 5% of SuSC nAChRs. Acetylcholine-evoked [(3) H]-GABA release from SuSC crude synaptosomal preparations is calcium dependent, blocked by the voltage-sensitive calcium channel blocker, cadmium, and the nAChR antagonist mecamylamine, but is unaffected by muscarinic, glutamatergic, P2X and 5-HT3 receptor antagonists. Approximately 50% of nAChR-mediated SuSC [(3) H]-GABA release is inhibited by α-conotoxin MII. However, the highly α6β2*-subtype-selective α-conotoxin PIA did not affect [(3) H]-GABA release. Nicotinic subunit-null mutant mouse experiments revealed that ACh-stimulated SuSC [(3) H]-GABA release is entirely β2 subunit-dependent. α4 subunit deletion decreased total function by >90%, and eliminated α-conotoxin MII-resistant release. ACh-stimulated SuSC [(3) H]-GABA release was unaffected by β3, α5 or α6 nicotinic subunit deletions. Together, these data suggest that a significant proportion of mouse SuSC nicotinic agonist-evoked GABA-release is mediated by a novel, α-conotoxin MII-sensitive α3α4β2 nAChR. The remaining α-conotoxin MII-resistant, nAChR agonist-evoked SuSC GABA release appears to be mediated via α4β2* subtype nAChRs.
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dos Santos Coura R, Granon S. Prefrontal neuromodulation by nicotinic receptors for cognitive processes. Psychopharmacology (Berl) 2012; 221:1-18. [PMID: 22249358 DOI: 10.1007/s00213-011-2596-6] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/06/2011] [Accepted: 11/17/2011] [Indexed: 11/30/2022]
Abstract
RATIONALE The prefrontal cortex (PFC) mediates executive functions, a set of control processes that optimize performance on cognitive tasks. It enables appropriate decision-making and mediates adapted behaviors, all processes impaired in psychiatric or degenerative disorders. Key players of normal functioning of the PFC are neurotransmitter (NT) systems arising from subcortical nuclei and targeting PFC subareas and, also, neuronal nicotinic acetylcholine receptors (nAChRs). These ion channels, located on multiple cell compartments in all brain areas, mediate direct cholinergic transmission and modulate the release of NTs that cross onto PFC neurons or interneurons. OBJECTIVE We compiled current knowledge concerning the role of nAChRs in NT release, focusing on the PFC. We point out plausible mechanisms of interaction among PFC circuits implicated in executive functions and emphasized the role of β2-containing nAChRs, the high-affinity receptors for acetylcholine (ACh). These receptors are more directly implicated in behavioral flexibility either when located on PFC neurons or in the monoaminergic or cholinergic systems targeting the PFC. RESULTS We shed light on potentially crucial roles played by nAChRs in complex interactions between local and afferent NTs. We show how they could act on cognition via PFC networks. CONCLUSIONS nAChRs are crucial for decision-making, during integration of emotional and motivational features, both mediated by different NT pathways in the PFC. We review the knowledge recently gained on cognitive functions in mice and our current understanding of PFC NT modulation. The combination of these data is expected to provide new hypotheses concerning the role of AChRs in cognitive processes.
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Grady SR, Wageman CR, Patzlaff NE, Marks MJ. Low concentrations of nicotine differentially desensitize nicotinic acetylcholine receptors that include α5 or α6 subunits and that mediate synaptosomal neurotransmitter release. Neuropharmacology 2012; 62:1935-43. [PMID: 22239849 DOI: 10.1016/j.neuropharm.2011.12.026] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2011] [Revised: 12/12/2011] [Accepted: 12/21/2011] [Indexed: 10/14/2022]
Abstract
Desensitization is a complex property of nicotinic acetylcholine receptors (nAChR). Several subtypes of nAChR have high sensitivity to nicotine and mediate effects of nicotine at concentrations found in blood of tobacco smokers. Desensitization of some of these receptor subtypes has been studied in model systems, however, other subtypes have been difficult to express heterologously in native forms. In addition, model systems may not have the same accessory molecules and post-translational modifications found in native populations. We have used wild-type and subunit null mutant mice to study desensitization properties of the high sensitivity α4β2-nAChRs including those that have α5 subunits at both GABAergic and dopaminergic nerve terminals. In addition, we have studied the desensitization of one subtype of α6β2-nAChRs at dopaminergic terminals using α4 subunit null mutant mice. Exposure to low nicotine concentrations, leads to rapid, but partial desensitization of activity mediated by these receptors. α4β2-nAChRs including α5 subunits show faster rates of recovery from desensitization than α4β2-nAChRs without α5. Inclusion of the α5 subunit significantly shifts the concentration response for desensitization to higher values, indicating that receptors with α5 subunits are less desensitized by a 10-min exposure to low concentrations of nicotine. Receptors with α6 subunits appear to desensitize to a lesser degree than those with α4 subunits, indicating that α6β2-nAChRs are somewhat resistant to desensitization by nicotine. These results highlight the importance of studying various receptor subtypes in native systems and how they may differentially respond to nicotine and to nicotinic drugs.
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Affiliation(s)
- Sharon R Grady
- Institute for Behavioral Genetics, University of Colorado, 447UCB, Boulder, CO 80309-0447, USA.
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Qiu C, Cheng S, Xia Y, Peng B, Tang Q, Tu B. Effects of subchronic benzo(a)pyrene exposure on neurotransmitter receptor gene expression in the rats hippocampus related with spatial learning and memory change. Toxicology 2011; 289:83-90. [DOI: 10.1016/j.tox.2011.07.012] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2011] [Revised: 07/18/2011] [Accepted: 07/28/2011] [Indexed: 10/17/2022]
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Dash B, Chang Y, Lukas RJ. Reporter mutation studies show that nicotinic acetylcholine receptor (nAChR) α5 Subunits and/or variants modulate function of α6*-nAChR. J Biol Chem 2011; 286:37905-37918. [PMID: 21873428 DOI: 10.1074/jbc.m111.264044] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
To further the understanding of functional α6α5*-nicotinic acetylcholine receptors (nAChR; the asterisk (*) indicates known or possible presence of other subunits), we have heterologously expressed in oocytes different, mouse or human, nAChR subunit combinations. Coexpression with wild-type α5 subunits or chimeric α5/β3 subunits (in which the human α5 subunit N-terminal, extracellular domain is linked to the remaining domains of the human β3 subunit) almost completely abolishes the very small amount of function seen for α6β4*-nAChR and does not induce function of α6β2*-nAChR. Coexpression with human α5(V9)'(S) subunits bearing a valine 290 to serine mutation in the 9' position of the second transmembrane domain does not rescue the function of α6β4*-nAChR or induce function of α6β2*-nAChR. However, coexpression with mutant chimeric α5/β3(V9)'(S) subunits has a gain-of-function effect (higher functional expression and agonist sensitivity and spontaneous opening inhibited by mecamylamine) on α6β4*-nAChR. Moreover, N143D + M145V mutations in the α6 subunit N-terminal domain enable α5/β3(V9)'(S) subunits to have a gain-of-function effect on α6β2*-nAChR. nAChR containing chimeric α6/α3 subunits plus either β2 or β4 subunits have some function that is modulated in the presence of α5 or α5/β3 subunits. Coexpression with α5/β3(V9)'(S) subunits has a gain-of-function effect more pronounced than that in the presence of α5(V9)'(S) subunits. Gain-of-function effects are dependent, sometimes subtly, on the nature and apparently the extracellular, cytoplasmic, and/or transmembrane domain topology of partner subunits. These studies yield insight into assembly of functional α6α5*-nAChR and provide tools for development of α6*-nAChR-selective ligands that could be important in the treatment of nicotine dependence, and perhaps other neurological diseases.
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Affiliation(s)
- Bhagirathi Dash
- Division of Neurobiology, Barrow Neurological Institute, Phoenix, Arizona 85013
| | - Yongchang Chang
- Division of Neurobiology, Barrow Neurological Institute, Phoenix, Arizona 85013
| | - Ronald J Lukas
- Division of Neurobiology, Barrow Neurological Institute, Phoenix, Arizona 85013.
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Tammimäki A, Horton WJ, Stitzel JA. Recent advances in gene manipulation and nicotinic acetylcholine receptor biology. Biochem Pharmacol 2011; 82:808-19. [PMID: 21704022 DOI: 10.1016/j.bcp.2011.06.014] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2011] [Revised: 06/07/2011] [Accepted: 06/08/2011] [Indexed: 11/26/2022]
Abstract
Pharmacological and immunological methods have been valuable for both identifying some native nicotinic acetylcholine receptor (nAChR) subtypes that exist in vivo and determining the neurobiological and behavioral role of certain nAChR subtypes. However, these approaches suffer from shortage of subtype specific ligands and reliable immunological reagents. Consequently, genetic approaches have been developed to complement earlier approaches to identify native nAChR subtypes and to assess the contribution of nAChRs to brain function and behavior. In this review we describe how assembly partners, knock-in mice and targeted lentiviral re-expression of genes have been utilized to improve our understanding of nAChR neurobiology. In addition, we summarize emerging genetic tools in nAChR research.
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Affiliation(s)
- Anne Tammimäki
- Institute for Behavioral Genetics, University of Colorado at Boulder, UCB 447, Boulder, CO 80309, United States.
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Miwa JM, Freedman R, Lester HA. Neural systems governed by nicotinic acetylcholine receptors: emerging hypotheses. Neuron 2011; 70:20-33. [PMID: 21482353 PMCID: PMC4418790 DOI: 10.1016/j.neuron.2011.03.014] [Citation(s) in RCA: 161] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/25/2011] [Indexed: 11/21/2022]
Abstract
Cholinergic neurons and nicotinic acetylcholine receptors (nAChRs) in the brain participate in diverse functions: reward, learning and memory, mood, sensory processing, pain, and neuroprotection. Nicotinic systems also have well-known roles in drug abuse. Here, we review recent insights into nicotinic function, linking exogenous and endogenous manipulations of nAChRs to alterations in synapses, circuits, and behavior. We also discuss how these contemporary advances can motivate attempts to exploit nicotinic systems therapeutically in Parkinson's disease, cognitive decline, epilepsy, and schizophrenia.
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Affiliation(s)
- Julie M. Miwa
- Division of Biology, California Institute of Technology, 1200 E. California Boulevard, Pasadena, CA 91125, USA
| | - Robert Freedman
- Department of Psychiatry and Pharmacology, University of Colorado Denver VA, 13001 F-546, Aurora, CO 80045, USA
| | - Henry A. Lester
- Division of Biology, California Institute of Technology, 1200 E. California Boulevard, Pasadena, CA 91125, USA
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Presynaptic nicotinic α7 and non-α7 receptors stimulate endogenous GABA release from rat hippocampal synaptosomes through two mechanisms of action. PLoS One 2011; 6:e16911. [PMID: 21346795 PMCID: PMC3034729 DOI: 10.1371/journal.pone.0016911] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2010] [Accepted: 01/17/2011] [Indexed: 11/19/2022] Open
Abstract
Background Although converging evidence has suggested that nicotinic acetylcholine receptors (nAChR) play a role in the modulation of GABA release in rat hippocampus, the specific involvement of different nAChR subtypes at presynaptic level is still a matter of debate. In the present work we investigated, using selective α7 and α4β2 nAChR agonists, the presence of different nAChR subtypes on hippocampal GABA nerve endings to assess to what extent and through which mechanisms they stimulate endogenous GABA release. Methodology/Findings All agonists elicited GABA overflow. Choline (Ch)-evoked GABA overflow was dependent to external Ca2+, but unaltered in the presence of Cd2+, tetrodotoxin (TTX), dihydro-β-erythroidine (DHβE) and 1-(4,4-Diphenyl-3-butenyl)-3-piperidinecarboxylic acid hydrochloride SKF 89976A. The effect of Ch was blocked by methyllycaconitine (MLA), α-bungarotoxin (α-BTX), dantrolene, thapsigargin and xestospongin C, suggesting that GABA release might be triggered by Ca2+ entry into synaptosomes through the α7 nAChR channel with the involvement of calcium from intracellular stores. Additionally, 5-Iodo-A-85380 dihydrochloride (5IA85380) elicited GABA overflow, which was Ca2+ dependent, blocked by Cd2+, and significantly inhibited by TTX and DHβE, but unaffected by MLA, SKF 89976A, thapsigargin and xestospongin C and dantrolene. These findings confirm the involvement of α4β2 nAChR in 5IA85380-induced GABA release that seems to occur following membrane depolarization and opening calcium channels. Conclusions/Significance Rat hippocampal synaptosomes possess both α7 and α4β2 nAChR subtypes, which can modulate GABA release via two distinct mechanisms of action. The finding that GABA release evoked by the mixture of sub-maximal concentration of 5IA85380 plus sub-threshold concentrations of Ch was significantly larger than that elicited by the sum of the effects of the two agonists is compatible with the possibility that they coexist on the same nerve terminals. These findings would provide the basis for possible selective pharmacological strategies to treat neuronal disorders that involve the dysfunction of hippocampal cholinergic system.
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Bonsi P, Cuomo D, Martella G, Madeo G, Schirinzi T, Puglisi F, Ponterio G, Pisani A. Centrality of striatal cholinergic transmission in Basal Ganglia function. Front Neuroanat 2011; 5:6. [PMID: 21344017 PMCID: PMC3036975 DOI: 10.3389/fnana.2011.00006] [Citation(s) in RCA: 100] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2010] [Accepted: 01/21/2011] [Indexed: 01/24/2023] Open
Abstract
Work over the past two decades revealed a previously unexpected role for striatal cholinergic interneurons in the context of basal ganglia function. The recognition that these interneurons are essential in synaptic plasticity and motor learning represents a significant step ahead in deciphering how the striatum processes cortical inputs, and why pathological circumstances cause motor dysfunction. Loss of the reciprocal modulation between dopaminergic inputs and the intrinsic cholinergic innervation within the striatum appears to be the trigger for pathophysiological changes occurring in basal ganglia disorders. Accordingly, there is now compelling evidence showing profound changes in cholinergic markers in these disorders, in particular Parkinson's disease and dystonia. Based on converging experimental and clinical evidence, we provide an overview of the role of striatal cholinergic transmission in physiological and pathological conditions, in the context of the pathogenesis of movement disorders.
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Affiliation(s)
- Paola Bonsi
- Laboratory of Neurophysiology and Plasticity, Fondazione Santa Lucia IRCCS Rome, Italy
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Culverhouse RC, Saccone NL, Stitzel JA, Wang JC, Steinbach JH, Goate AM, Schwantes-An TH, Grucza RA, Stevens VL, Bierut LJ. Uncovering hidden variance: pair-wise SNP analysis accounts for additional variance in nicotine dependence. Hum Genet 2011; 129:177-88. [PMID: 21079997 PMCID: PMC3030551 DOI: 10.1007/s00439-010-0911-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2010] [Accepted: 11/01/2010] [Indexed: 02/01/2023]
Abstract
Results from genome-wide association studies of complex traits account for only a modest proportion of the trait variance predicted to be due to genetics. We hypothesize that joint analysis of polymorphisms may account for more variance. We evaluated this hypothesis on a case-control smoking phenotype by examining pairs of nicotinic receptor single-nucleotide polymorphisms (SNPs) using the Restricted Partition Method (RPM) on data from the Collaborative Genetic Study of Nicotine Dependence (COGEND). We found evidence of joint effects that increase explained variance. Four signals identified in COGEND were testable in independent American Cancer Society (ACS) data, and three of the four signals replicated. Our results highlight two important lessons: joint effects that increase the explained variance are not limited to loci displaying substantial main effects, and joint effects need not display a significant interaction term in a logistic regression model. These results suggest that the joint analyses of variants may indeed account for part of the genetic variance left unexplained by single SNP analyses. Methodologies that limit analyses of joint effects to variants that demonstrate association in single SNP analyses, or require a significant interaction term, will likely miss important joint effects.
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Affiliation(s)
- Robert C Culverhouse
- Division of General Medical Sciences, Department of Medicine, Washington University, Saint Louis, MO 63110, USA.
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Nagumo Y, Takeuchi Y, Imoto K, Miyata M. Synapse- and subtype-specific modulation of synaptic transmission by nicotinic acetylcholine receptors in the ventrobasal thalamus. Neurosci Res 2010; 69:203-13. [PMID: 21145925 DOI: 10.1016/j.neures.2010.12.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2010] [Revised: 11/29/2010] [Accepted: 12/02/2010] [Indexed: 11/25/2022]
Abstract
The rodent thalamic ventrobasal complex (VB) which is a subdivision of somatosensory thalamus receives two excitatory inputs through the medial lemniscal synapse, which is a sensory afferent synapse, and the corticothalamic synapse from layer VI of the somatosensory cortex. In addition, the VB also receives cholinergic inputs from the brain stem, and nicotinic acetylcholine receptors (nAChRs) are highly expressed in the VB. Little is known, however, how acetylcholine (ACh) modulates synaptic transmission at the medial lemniscal and corticothalamic synapses in the VB. Furthermore, it remains unclear which subtype of nAChRs contributes to VB synaptic transmission. We report here that the activation of nAChRs presynaptically depressed corticothalamic synaptic transmission, whereas it did not affect medial lemniscal synaptic transmission in juvenile mice. This presynaptic modulation was mediated by the activation of nAChRs that contained α4 and β2 subunit, but not by α7 nAChRs. Moreover, galanthamine, an allosteric modulator of α4β2α5 nAChR, enhanced the ACh-induced depression of corticothalamic excitatory postsynaptic currents (EPSCs), indicating that α4β2α5 nAChRs at corticothalamic axon terminals specifically contribute to the depression of corticothalamic synaptic transmission.
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Affiliation(s)
- Yasuyuki Nagumo
- Department of Physiology, Tokyo Women's Medical University, 8-1 Kawada-cho, Shinjuku-ku, Tokyo 162-8666, Japan
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