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Chrestia JF, Turani O, Araujo NR, Hernando G, Esandi MDC, Bouzat C. Regulation of nicotinic acetylcholine receptors by post-translational modifications. Pharmacol Res 2023; 190:106712. [PMID: 36863428 DOI: 10.1016/j.phrs.2023.106712] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/12/2023] [Revised: 02/21/2023] [Accepted: 02/24/2023] [Indexed: 03/04/2023]
Abstract
Nicotinic acetylcholine receptors (nAChRs) comprise a family of pentameric ligand-gated ion channels widely distributed in the central and peripheric nervous system and in non-neuronal cells. nAChRs are involved in chemical synapses and are key actors in vital physiological processes throughout the animal kingdom. They mediate skeletal muscle contraction, autonomic responses, contribute to cognitive processes, and regulate behaviors. Dysregulation of nAChRs is associated with neurological, neurodegenerative, inflammatory and motor disorders. In spite of the great advances in the elucidation of nAChR structure and function, our knowledge about the impact of post-translational modifications (PTMs) on nAChR functional activity and cholinergic signaling has lagged behind. PTMs occur at different steps of protein life cycle, modulating in time and space protein folding, localization, function, and protein-protein interactions, and allow fine-tuned responses to changes in the environment. A large body of evidence demonstrates that PTMs regulate all levels of nAChR life cycle, with key roles in receptor expression, membrane stability and function. However, our knowledge is still limited, restricted to a few PTMs, and many important aspects remain largely unknown. There is thus a long way to go to decipher the association of aberrant PTMs with disorders of cholinergic signaling and to target PTM regulation for novel therapeutic interventions. In this review we provide a comprehensive overview of what is known about how different PTMs regulate nAChR.
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Affiliation(s)
- Juan Facundo Chrestia
- Instituto de Investigaciones Bioquímicas de Bahía Blanca, Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur-Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Bahía Blanca 8000, Argentina
| | - Ornella Turani
- Instituto de Investigaciones Bioquímicas de Bahía Blanca, Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur-Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Bahía Blanca 8000, Argentina
| | - Noelia Rodriguez Araujo
- Instituto de Investigaciones Bioquímicas de Bahía Blanca, Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur-Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Bahía Blanca 8000, Argentina
| | - Guillermina Hernando
- Instituto de Investigaciones Bioquímicas de Bahía Blanca, Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur-Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Bahía Blanca 8000, Argentina
| | - María Del Carmen Esandi
- Instituto de Investigaciones Bioquímicas de Bahía Blanca, Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur-Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Bahía Blanca 8000, Argentina
| | - Cecilia Bouzat
- Instituto de Investigaciones Bioquímicas de Bahía Blanca, Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur-Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Bahía Blanca 8000, Argentina.
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Abburi C, McDaid J. Ethanol interaction with α3β4 nicotinic acetylcholine receptors in neurons of the laterodorsal tegmentum. Alcohol Clin Exp Res 2021; 45:2495-2505. [PMID: 34625982 DOI: 10.1111/acer.14727] [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: 03/30/2021] [Revised: 09/28/2021] [Accepted: 10/04/2021] [Indexed: 11/28/2022]
Abstract
BACKGROUND Nicotinic acetylcholine receptors (nAChRs) play a key role in the rewarding effects of ethanol (EtOH), and while several nAChR subtypes have been implicated, attention has recently shifted to a role for the α3β4 nAChR. The laterodorsal tegmental nucleus (LDTg), a brainstem cholinergic nucleus that sends excitatory projections to the ventral tegmental area, is an Integral part of the brain reward pathway. Here we investigate a potential role for LDTg α3β4 nAChRs in EtOH self-administration and reward. METHODS Sprague-Dawley rats were given ad libitum access to a 20% EtOH solution, as part of a two-bottle choice paradigm. Approximately 1 week after removal of EtOH access, we measured LDTg α3β4 nAChR current responses to focal application of acetylcholine (ACh), using whole-cell patch clamp electrophysiology recordings in acute brain slices. In addition, we used whole-cell electrophysiology to assess the acute effects of EtOH on the sensitivity of LDTg α3β4 nAChRs. RESULTS Focal application of ACh onto LDTg neurons resulted in large α3β4 nAChR-mediated inward currents, the magnitude of which showed a positive correlation with levels of EtOH self-administration. In addition, using brain slices taken from EtOH-naïve rats, bath application of EtOH resulted in a moderate potentiation of LDTg α3β4 nAChR sensitivity. CONCLUSIONS Using a rat model, increased α3β4 nAChR function was associated with greater EtOH self-administration, with α3β4 nAChR function also acutely potentiated by EtOH. Assuming that similar findings apply to humans, the α3β4 nAChR could be a therapeutic target in the treatment of EtOH use disorder.
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Affiliation(s)
- Chandrika Abburi
- Department of Anesthesia and Critical Care, University of Chicago, 5841 South Maryland Avenue, Chicago, Illinois, 60637, USA
| | - John McDaid
- Department of Anesthesia and Critical Care, University of Chicago, 5841 South Maryland Avenue, Chicago, Illinois, 60637, USA
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Cifelli P, Di Angelantonio S, Alfano V, Morano A, De Felice E, Aronica E, Ruffolo G, Palma E. Dissecting the Molecular Determinants of GABA A Receptors Current Rundown, a Hallmark of Refractory Human Epilepsy. Brain Sci 2021; 11:brainsci11040441. [PMID: 33808090 PMCID: PMC8066365 DOI: 10.3390/brainsci11040441] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2021] [Revised: 03/24/2021] [Accepted: 03/28/2021] [Indexed: 11/16/2022] Open
Abstract
GABAA receptors-(Rs) are fundamental for the maintenance of an efficient inhibitory function in the central nervous system (CNS). Their dysfunction is associated with a wide range of CNS disorders, many of which characterized by seizures and epilepsy. Recently, an increased use-dependent desensitization due to a repetitive GABA stimulation (GABAA current rundown) of GABAARs has been associated with drug-resistant temporal lobe epilepsy (TLE). Here, we aimed to investigate the molecular determinants of GABAA current rundown with two different heterologous expression systems (Xenopus oocytes and human embryonic kidney cells; HEK) which allowed us to manipulate receptor stoichiometry and to study the GABAA current rundown on different GABAAR configurations. To this purpose, we performed electrophysiology experiments using two-electrode voltage clamp in oocytes and confirming part of our results in HEK. We found that different degrees of GABAA current rundown can be associated with the expression of different GABAAR β-subunits reaching the maximum current decrease when functional α1β2 receptors are expressed. Furthermore, the blockade of phosphatases can prevent the current rundown observed in α1β2 GABAARs. Since GABAAR represents one important therapeutic target in the treatment of human epilepsy, our results could open new perspectives on the therapeutic management of drug-resistant patients showing a GABAergic impairment.
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Affiliation(s)
- Pierangelo Cifelli
- Department of Applied Clinical and Biotechnological Sciences, University of L’Aquila, 67100 L’Aquila, Italy;
| | - Silvia Di Angelantonio
- Department of Physiology and Pharmacology, Istituto Pasteur-Fondazione Cenci Bolognetti, University of Rome Sapienza, 00185 Rome, Italy; (S.D.A.); (V.A.); (E.D.F.); (E.P.)
- Center for Life Nanoscience, Istituto Italiano di Tecnologia (IIT), 00161 Rome, Italy
| | - Veronica Alfano
- Department of Physiology and Pharmacology, Istituto Pasteur-Fondazione Cenci Bolognetti, University of Rome Sapienza, 00185 Rome, Italy; (S.D.A.); (V.A.); (E.D.F.); (E.P.)
| | - Alessandra Morano
- Department of Human Neuroscience, University of Rome Sapienza, 00185 Rome, Italy;
| | - Eleonora De Felice
- Department of Physiology and Pharmacology, Istituto Pasteur-Fondazione Cenci Bolognetti, University of Rome Sapienza, 00185 Rome, Italy; (S.D.A.); (V.A.); (E.D.F.); (E.P.)
| | - Eleonora Aronica
- Department of (Neuro)Pathology, Amsterdam UMC, University of Amsterdam, 1105 Amsterdam, The Netherlands;
- Stichting Epilepsie Instellingen Nederland, 0397 Heemstede, The Netherlands
| | - Gabriele Ruffolo
- Department of Physiology and Pharmacology, Istituto Pasteur-Fondazione Cenci Bolognetti, University of Rome Sapienza, 00185 Rome, Italy; (S.D.A.); (V.A.); (E.D.F.); (E.P.)
- Correspondence:
| | - Eleonora Palma
- Department of Physiology and Pharmacology, Istituto Pasteur-Fondazione Cenci Bolognetti, University of Rome Sapienza, 00185 Rome, Italy; (S.D.A.); (V.A.); (E.D.F.); (E.P.)
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Takahashi T, Yoshida T, Harada K, Miyagi T, Hashimoto K, Hide I, Tanaka S, Irifune M, Sakai N. Component of nicotine-induced intracellular calcium elevation mediated through α3- and α5-containing nicotinic acetylcholine receptors are regulated by cyclic AMP in SH-SY 5Y cells. PLoS One 2020; 15:e0242349. [PMID: 33253222 PMCID: PMC7703979 DOI: 10.1371/journal.pone.0242349] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2020] [Accepted: 11/01/2020] [Indexed: 12/03/2022] Open
Abstract
The pathway from the medial habenular nucleus to the interpeduncular nucleus, in which nicotinic acetylcholine receptor (nAChR) including the α3 and α5 subunits (α3 * and α5 * nAChRs) are expressed, is implicated in nicotine dependence. We investigated whether α3 * and α5 * nAChRs are regulated by cAMP using SH-SY5Y cells to clarify the significance of these receptors in nicotine dependence. We analyzed the nicotine-induced elevation of intracellular Ca2+ ([Ca2+]i). Nicotine induces a concentration-dependent increase in [Ca2+]i. The elimination of Ca2+ from extracellular fluid or intracellular stores demonstrated that the nicotine-induced [Ca2+]i elevation was due to extracellular influx and intracellular mobilization. The effects of tubocurarine on nicotine-induced [Ca2+]i elevation and current suggest that intracellular mobilization is caused by plasma membrane-permeating nicotine. The inhibition of α3 *, α5 *, α7 nAChR and voltage-gated Ca2+ channels by using siRNAs and selective antagonists revealed the involvement of these nAChR subunits and channels in nicotine-induced [Ca2+]i elevation. To distinguish and characterize the α3 * and α5 * nAChR-mediated Ca2+ influx, we measured the [Ca2+]i elevation induced by nonmembrane-permeating acetylcholine when muscarinic receptors, α7nAChR and Ca2+ channels were blocked. Under this condition, the [Ca2+]i elevation was significantly inhibited with a 48-h treatment of dibutyryl cAMP, which was accompanied by the downregulation of α3 and β4 mRNA. These findings suggest that α3 * and α5 * nAChR-mediated Ca2+ influx is possibly regulated by cAMP at the transcriptional level.
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Affiliation(s)
- Tamayo Takahashi
- Department of Molecular and Pharmacological Neuroscience, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan
- Department of Dental Anesthesiology, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan
| | - Takayuki Yoshida
- Department of Neurophysiology, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan
| | - Kana Harada
- Department of Molecular and Pharmacological Neuroscience, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan
| | - Tatsuhiko Miyagi
- Department of Molecular and Pharmacological Neuroscience, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan
| | - Kouichi Hashimoto
- Department of Neurophysiology, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan
| | - Izumi Hide
- Department of Molecular and Pharmacological Neuroscience, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan
| | - Shigeru Tanaka
- Department of Molecular and Pharmacological Neuroscience, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan
| | - Masahiro Irifune
- Department of Dental Anesthesiology, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan
| | - Norio Sakai
- Department of Molecular and Pharmacological Neuroscience, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan
- * E-mail:
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Bavan S, Kim CH, Henderson BJ, Lester HA. Chronic Menthol Does Not Change Stoichiometry or Functional Plasma Membrane Levels of Mouse α3 β4-Containing Nicotinic Acetylcholine Receptors. Mol Pharmacol 2019; 95:398-407. [PMID: 30670481 PMCID: PMC6399576 DOI: 10.1124/mol.118.114769] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2018] [Accepted: 01/12/2019] [Indexed: 11/22/2022] Open
Abstract
Heteromeric α3β4 nicotinic acetylcholine (ACh) receptors (nAChRs) are pentameric ligand-gated cation channels that include at least two α3 and two β4 subunits. They have functions in peripheral tissue and peripheral and central nervous systems. We examined the effects of chronic treatment with menthol, a major flavor additive in tobacco cigarettes and electronic nicotine delivery systems, on mouse α3β4 nAChRs transiently transfected into neuroblastoma-2a cells. Chronic menthol treatment at 500 nM, near the estimated menthol concentration in the brain following cigarette smoking, altered neither the [ACh]-response relationship nor Zn2+ sensitivity of ACh-evoked currents, suggesting that menthol does not change α3β4 nAChR subunit stoichiometry. Chronic menthol treatment failed to change the current density (peak current amplitude/cell capacitance) of 100 μM ACh-evoked currents. Chronic menthol treatment accelerated desensitization of 100 and 200 μM ACh-evoked currents. Chronic nicotine treatment (250 μM) decreased ACh-induced currents, and we found no additional effect of including chronic menthol. These data contrast with previously reported, marked effects of chronic menthol on β2* nAChRs studied in the same expression system. Mechanistically, the data support the emerging interpretation that both chronic menthol and chronic nicotine act on nAChRs in the early exocytotic pathway, and that this pathway does not present a rate-limiting step to the export of α3β4 nAChRs; these nAChRs include endoplasmic reticulum (ER) export motifs but not ER retention motifs. Previous reports show that smoking mentholated cigarettes enhances tobacco addiction; but our results show that this effect is unlikely to arise via menthol actions on α3β4 nAChRs.
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Affiliation(s)
- Selvan Bavan
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California (S.B., C.H.K., H.A.L.); and Department of Biomedical Sciences, Joan C. Edwards School of Medicine at Marshall University, Huntington, West Virginia (B.J.H.)
| | - Charlene H Kim
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California (S.B., C.H.K., H.A.L.); and Department of Biomedical Sciences, Joan C. Edwards School of Medicine at Marshall University, Huntington, West Virginia (B.J.H.)
| | - Brandon J Henderson
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California (S.B., C.H.K., H.A.L.); and Department of Biomedical Sciences, Joan C. Edwards School of Medicine at Marshall University, Huntington, West Virginia (B.J.H.)
| | - Henry A Lester
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California (S.B., C.H.K., H.A.L.); and Department of Biomedical Sciences, Joan C. Edwards School of Medicine at Marshall University, Huntington, West Virginia (B.J.H.)
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Grewal AK, Singh N, Singh TG. Neuroprotective effect of pharmacological postconditioning on cerebral ischaemia-reperfusion-induced injury in mice. ACTA ACUST UNITED AC 2019; 71:956-970. [PMID: 30809806 DOI: 10.1111/jphp.13073] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2018] [Accepted: 01/01/2019] [Indexed: 12/31/2022]
Abstract
OBJECTIVES To investigate the mechanism of neuroprotection rendered via pharmacological postconditioning in cerebral ischaemia-reperfusion-induced injury in mice. METHODS Pharmacological postconditioning is strategy which either involves hindering deleterious pathway or inducing modest stress level which triggers intracellular defence pathway to sustain more vigorous insult leading to conditioning. Hence, in current research we explored the potentiality of CGS21680 (0.5 mg/kg; i.p), an adenosine A2 A receptor agonist and PTEN inhibitor, SF1670 (3 mg/kg; i.p.) to trigger postconditioning after inducing cerebral global ischaemia (17 min) and reperfusion (24 h)-induced injury via occlusion of both carotid arteries. Mice were also given treatment with LY294002 (1.5 mg/kg; i.p.), a PI3K inhibitor and adenosine A2 A receptor antagonist, Istradefylline (2 mg/kg; i.p.), to establish the precise mechanism of postconditioning. Various biochemical and behavioural parameters were assessed to examine the effect of pharmacological postconditioning. KEY FINDINGS Pharmacological postconditioning induced with CGS21680 and SF1670 attenuated the infarction along with improved behavioural and biochemical parameters in comparison with ischaemia-reperfusion control group. The outcome of postconditioning with CGS21680 and SF1670 was significantly reversed by LY294002 and Istradefylline, respectively. CONCLUSIONS The neuroprotective effects of CGS21680 and SF1670 postconditioning on cerebral ischaemia-reperfusion injury may be due to PI3K/Akt pathway activation.
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Affiliation(s)
- Amarjot Kaur Grewal
- Department of Pharmacology, Chitkara college of Pharmacy, Chitkara University, Patiala, India
| | - Nirmal Singh
- Department of Pharmaceutical Sciences and Drug Research, Punjabi University, Patiala, India
| | - Thakur Gurjeet Singh
- Department of Pharmacology, Chitkara college of Pharmacy, Chitkara University, Patiala, India
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Qian J, Mummalaneni S, Grider JR, Damaj MI, Lyall V. Nicotinic acetylcholine receptors (nAChRs) are expressed in Trpm5 positive taste receptor cells (TRCs). PLoS One 2018; 13:e0190465. [PMID: 29293602 PMCID: PMC5749851 DOI: 10.1371/journal.pone.0190465] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2017] [Accepted: 12/17/2017] [Indexed: 12/15/2022] Open
Abstract
Nicotine evokes chorda tympani (CT) taste nerve responses and an aversive behavior in Trpm5 knockout (KO) mice. The agonists and antagonists of nicotinic acetylcholine receptors (nAChRs) modulate neural and behavioral responses to nicotine in wildtype (WT) mice, Trpm5 KO mice and rats. This indicates that nicotine evokes bitter taste by activating a Trpm5-dependent pathway and a Trpm5-independent but nAChR-dependent pathway. Rat CT responses to ethanol are also partially inhibited by nAChR blockers, mecamylamine and dihydro-β-erythroidine. This indicates that a component of the bitter taste of ethanol is also nAChR-dependent. However, at present the expression and localization of nAChR subunits has not been investigated in detail in taste receptor cells (TRCs). To this end, in situ hybridization, immunohistochemistry and q-RT-PCR techniques were utilized to localize nAChR subunits in fungiform and circumvallate TRCs in WT mice, Trpm5-GFP transgenic mice, nAChR KO mice, and rats. The expression of mRNAs for α7, β2 and β4 nAChR subunits was observed in a subset of rat and WT mouse circumvallate and fungiform TRCs. Specific α3, α4, α7, β2, and β4 antibodies localized to a subset of WT mouse circumvallate and fungiform TRCs. In Trpm5-GFP mice α3, α4, α7, and β4 antibody binding was observed in a subset of Trpm5-positive circumvallate TRCs. Giving nicotine (100 μg/ml) in drinking water to WT mice for 3 weeks differentially increased the expression of α3, α4, α5, α6, α7, β2 and β4 mRNAs in circumvallate TRCs to varying degrees. Giving ethanol (5%) in drinking water to WT mice induced an increase in the expression of α5 and β4 mRNAs in circumvallate TRCs with a significant decrease in the expression of α3, α6 and β2 mRNAs. We conclude that nAChR subunits are expressed in Trpm5-positive TRCs and their expression levels are differentially altered by chronic oral exposure to nicotine and ethanol.
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Affiliation(s)
- Jie Qian
- Physiology and Biophysics Virginia Commonwealth University, Richmond, VA, United States of America
| | - Shobha Mummalaneni
- Physiology and Biophysics Virginia Commonwealth University, Richmond, VA, United States of America
| | - John R. Grider
- Physiology and Biophysics Virginia Commonwealth University, Richmond, VA, United States of America
| | - M. Imad Damaj
- Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, VA, United States of America
| | - Vijay Lyall
- Physiology and Biophysics Virginia Commonwealth University, Richmond, VA, United States of America
- * E-mail:
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Kawahata I, Yamakuni T. Imidacloprid, a neonicotinoid insecticide, facilitates tyrosine hydroxylase transcription and phenylethanolamine N-methyltransferase mRNA expression to enhance catecholamine synthesis and its nicotine-evoked elevation in PC12D cells. Toxicology 2017; 394:84-92. [PMID: 29246838 DOI: 10.1016/j.tox.2017.12.004] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2017] [Revised: 12/08/2017] [Accepted: 12/11/2017] [Indexed: 11/30/2022]
Abstract
Imidacloprid is a neonicotinoid insecticide acting as an agonist of nicotinic acetylcholine receptors (nAChRs) in the target insects. However, questions about the safety to mammals, including human have emerged. Overactivation of mammalian peripheral catecholaminergic systems leads to onset of tachycardia, hypertension, vomiting, etc., which have been observed in acutely imidacloprid-poisoned patients as well. Physiological activation of the nAChRs is known to drive catecholamine biosynthesis and secretion in mammalian adrenal chromaffin cells. Yet, the impacts of imidacloprid on the catecholaminergic function of the chromaffin cells remain to be evaluated. In this study using PC12D cells, a catecholaminergic cell line derived from the medulla chromaffin-cell tumors of rat adrenal gland, we examined whether imidacloprid itself could impact the catecholamine-synthesizing ability. Imidacloprid alone did facilitate tyrosine hydroxylase (TH) transcription via activation of α3β4 nAChR and the α7 subunit-comprising receptor. The insecticide showed the TH transcription-facilitating ability at the concentrations of 3 and 30 μM, at which acetylcholine is known to produce physiological responses, including catecholamine secretion through the nAChRs in adrenal chromaffin cells. The insecticide-facilitated TH transcription was also dependent on PKA- and RhoA-mediated signaling pathways. The insecticide coincidentally raised levels of TH and phenylethanolamine N-methyltransferase (PNMT) mRNA, and as a consequence, increased catecholamine production, although the efficacy of the neonicotinoid was lesser than that of nicotine, indicating its partial agonist-like action. Intriguingly, in cultured rat adrenal chromaffin cells, imidacloprid did increase levels of TH and PNMT protein. When the chromaffin cells were treated with nicotine in the presence of the insecticide, nicotine-elevated adrenaline production was enhanced due to facilitation of nicotine-increased TH and PNMT protein expression, and simultaneous enhancement of nicotine-elevated adrenaline secretion also took place. These findings thus suggest that imidacloprid may facilitate the physiological functions of adrenal glands in mammals.
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Affiliation(s)
- Ichiro Kawahata
- Department of Pharmacology, Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai, Japan
| | - Tohru Yamakuni
- Department of Pharmacology, Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai, Japan.
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Sang L, Dick IE, Yue DT. Protein kinase A modulation of CaV1.4 calcium channels. Nat Commun 2016; 7:12239. [PMID: 27456671 PMCID: PMC4963476 DOI: 10.1038/ncomms12239] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2015] [Accepted: 06/07/2016] [Indexed: 11/19/2022] Open
Abstract
The regulation of L-type Ca2+ channels by protein kinase A (PKA) represents a crucial element within cardiac, skeletal muscle and neurological systems. Although much work has been done to understand this regulation in cardiac CaV1.2 Ca2+ channels, relatively little is known about the closely related CaV1.4 L-type Ca2+ channels, which feature prominently in the visual system. Here we find that CaV1.4 channels are indeed modulated by PKA phosphorylation within the inhibitor of Ca2+-dependent inactivation (ICDI) motif. Phosphorylation of this region promotes the occupancy of calmodulin on the channel, thus increasing channel open probability (PO) and Ca2+-dependent inactivation. Although this interaction seems specific to CaV1.4 channels, introduction of ICDI1.4 to CaV1.3 or CaV1.2 channels endows these channels with a form of PKA modulation, previously unobserved in heterologous systems. Thus, this mechanism may not only play an important role in the visual system but may be generalizable across the L-type channel family. Phosphorylation of L-type calcium CaV channels by protein kinase A is essential for several physiological events. Here, the authors show how this kinase regulates CaV1.4 activity, suggesting a general regulatory mechanism for all L-type calcium channels.
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Affiliation(s)
- Lingjie Sang
- Calcium Signals Laboratory, Department of Biomedical Engineering, The Johns Hopkins University School of Medicine, Ross Building, Room 713, 720 Rutland Avenue, Baltimore, Maryland 21205, USA
| | - Ivy E Dick
- Calcium Signals Laboratory, Department of Biomedical Engineering, The Johns Hopkins University School of Medicine, Ross Building, Room 713, 720 Rutland Avenue, Baltimore, Maryland 21205, USA
| | - David T Yue
- Calcium Signals Laboratory, Department of Biomedical Engineering, The Johns Hopkins University School of Medicine, Ross Building, Room 713, 720 Rutland Avenue, Baltimore, Maryland 21205, USA.,Department of Neuroscience, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA
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McDaid J, Abburi C, Wolfman SL, Gallagher K, McGehee DS. Ethanol-Induced Motor Impairment Mediated by Inhibition of α7 Nicotinic Receptors. J Neurosci 2016; 36:7768-78. [PMID: 27445152 PMCID: PMC4951579 DOI: 10.1523/jneurosci.0154-16.2016] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2016] [Revised: 06/03/2016] [Accepted: 06/07/2016] [Indexed: 01/30/2023] Open
Abstract
UNLABELLED Nicotine and ethanol (EtOH) are among the most widely co-abused substances, and nicotinic acetylcholine receptors (nAChRs) contribute to the behavioral effects of both drugs. Along with their role in addiction, nAChRs also contribute to motor control circuitry. The α7 nAChR subtype is highly expressed in the laterodorsal tegmental nucleus (LDTg), a brainstem cholinergic center that contributes to motor performance through its projections to thalamic motor relay centers, including the mediodorsal thalamus. We demonstrate that EtOH concentrations just above the legal limits for intoxication in humans can inhibit α7 nAChRs in LDTg neurons from rats. This EtOH-induced inhibition is mediated by a decrease in cAMP/PKA signaling. The α7 nAChR-positive allosteric modulator PNU120596 [N-(5-chloro-2,4-dimethoxyphenyl)-N'-(5-methyl-3-isoxazolyl)-urea], which interferes with receptor desensitization, completely eliminated EtOH modulation of these receptors. These data suggest that EtOH inhibits α7 responses through a PKA-dependent enhancement of receptor desensitization. EtOH also inhibited the effects of nicotine at presynaptic α7 nAChRs on glutamate terminals in the mediodorsal thalamus. In vivo administration of PNU120596 either into the cerebral ventricles or directly into the mediodorsal thalamus attenuated EtOH-induced motor impairment. Thus, α7 nAChRs are likely important mediators of the motor impairing effects of moderate EtOH consumption. SIGNIFICANCE STATEMENT The motor-impairing effects of ethanol contribute to intoxication-related injury and death. Here we explore the cellular and neural circuit mechanisms underlying ethanol-induced motor impairment. Physiologically relevant concentrations of ethanol inhibit activity of a nicotinic receptor subtype that is expressed in brain areas associated with motor control. That receptor inhibition is mediated by decreased receptor phosphorylation, suggesting an indirect modulation of cell signaling pathways to achieve the physiological effects.
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Affiliation(s)
- John McDaid
- Department of Anesthesia and Critical Care and
| | | | - Shannon L Wolfman
- Committee on Neurobiology, University of Chicago, Chicago, Illinois 60637
| | | | - Daniel S McGehee
- Department of Anesthesia and Critical Care and Committee on Neurobiology, University of Chicago, Chicago, Illinois 60637
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Bernareggi A, Luin E, Pavan B, Parato G, Sciancalepore M, Urbani R, Lorenzon P. Adenosine enhances acetylcholine receptor channel openings and intracellular calcium 'spiking' in mouse skeletal myotubes. Acta Physiol (Oxf) 2015; 214:467-80. [PMID: 25683861 DOI: 10.1111/apha.12473] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2014] [Revised: 10/23/2014] [Accepted: 02/11/2015] [Indexed: 12/26/2022]
Abstract
AIMS The autocrine activity of the embryonic isoform of the nicotinic acetylcholine receptor is crucial for the correct differentiation and trophism of skeletal muscle cells before innervation. The functional activity of extracellular adenosine and adenosine receptor subtypes expressed in differentiating myotubes is still unknown. In this study, we performed a detailed analysis of the role of adenosine receptor-mediated effects on the autocrine-mediated nicotinic acetylcholine receptor channel openings and the associated spontaneous intracellular calcium 'spikes' generated in differentiating mouse myotubes in vitro. METHODS Cell-attached patch-clamp recordings and intracellular calcium imaging experiments were performed in contracting myotubes derived from mouse satellite cells. RESULTS The endogenous extracellular adenosine and the adenosine receptor-mediated activity modulated the properties of the embryonic isoform of the nicotinic acetylcholine receptor in myotubes in vitro, by increasing the mean open time and the open probability of the ion channel, and sustaining nicotinic acetylcholine receptor-driven intracellular [Ca(2+) ]i 'spikes'. The pharmacological characterization of the adenosine receptor-mediated effects suggested a prevalent involvement of the A2B adenosine receptor subtype. CONCLUSION We propose that the interplay between endogenous adenosine and nicotinic acetylcholine receptors represents a potential novel strategy to improve differentiation/regeneration of skeletal muscle.
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Affiliation(s)
- A. Bernareggi
- Department of Life Sciences; University of Trieste; via A. Fleming 22 Trieste I-34127 Italy
- B.R.A.I.N. Centre for Neuroscience; via Fleming 22 Trieste I-34127 Italy
| | - E. Luin
- Department of Life Sciences; University of Trieste; via A. Fleming 22 Trieste I-34127 Italy
- B.R.A.I.N. Centre for Neuroscience; via Fleming 22 Trieste I-34127 Italy
| | - B. Pavan
- Department of Life Sciences and Biotechnology; University of Ferrara; Via L. Borsari 46 Ferrara I-44121 Italy
| | - G. Parato
- Department of Life Sciences; University of Trieste; via A. Fleming 22 Trieste I-34127 Italy
- B.R.A.I.N. Centre for Neuroscience; via Fleming 22 Trieste I-34127 Italy
| | - M. Sciancalepore
- Department of Life Sciences; University of Trieste; via A. Fleming 22 Trieste I-34127 Italy
- B.R.A.I.N. Centre for Neuroscience; via Fleming 22 Trieste I-34127 Italy
| | - R. Urbani
- Department of Life Sciences; University of Trieste; via A. Fleming 22 Trieste I-34127 Italy
| | - P. Lorenzon
- Department of Life Sciences; University of Trieste; via A. Fleming 22 Trieste I-34127 Italy
- B.R.A.I.N. Centre for Neuroscience; via Fleming 22 Trieste I-34127 Italy
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12
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Nicotinic Acetylcholine Receptor (nAChR) Dependent Chorda Tympani Taste Nerve Responses to Nicotine, Ethanol and Acetylcholine. PLoS One 2015; 10:e0127936. [PMID: 26039516 PMCID: PMC4454666 DOI: 10.1371/journal.pone.0127936] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2015] [Accepted: 04/20/2015] [Indexed: 12/12/2022] Open
Abstract
Nicotine elicits bitter taste by activating TRPM5-dependent and TRPM5-independent but neuronal nAChR-dependent pathways. The nAChRs represent common targets at which acetylcholine, nicotine and ethanol functionally interact in the central nervous system. Here, we investigated if the nAChRs also represent a common pathway through which the bitter taste of nicotine, ethanol and acetylcholine is transduced. To this end, chorda tympani (CT) taste nerve responses were monitored in rats, wild-type mice and TRPM5 knockout (KO) mice following lingual stimulation with nicotine free base, ethanol, and acetylcholine, in the absence and presence of nAChR agonists and antagonists. The nAChR modulators: mecamylamine, dihydro-β-erythroidine, and CP-601932 (a partial agonist of the α3β4* nAChR), inhibited CT responses to nicotine, ethanol, and acetylcholine. CT responses to nicotine and ethanol were also inhibited by topical lingual application of 8-chlorophenylthio (CPT)-cAMP and loading taste cells with [Ca2+]i by topical lingual application of ionomycin + CaCl2. In contrast, CT responses to nicotine were enhanced when TRC [Ca2+]i was reduced by topical lingual application of BAPTA-AM. In patch-clamp experiments, only a subset of isolated rat fungiform taste cells exposed to nicotine responded with an increase in mecamylamine-sensitive inward currents. We conclude that nAChRs expressed in a subset of taste cells serve as common receptors for the detection of the TRPM5-independent bitter taste of nicotine, acetylcholine and ethanol.
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Santafe MM, Priego M, Obis T, Garcia N, Tomàs M, Lanuza MA, Tomàs J. Adenosine receptors and muscarinic receptors cooperate in acetylcholine release modulation in the neuromuscular synapse. Eur J Neurosci 2015; 42:1775-87. [PMID: 25892551 DOI: 10.1111/ejn.12922] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2014] [Revised: 04/15/2015] [Accepted: 04/15/2015] [Indexed: 11/30/2022]
Abstract
Adenosine receptors (ARs) are present in the motor terminals at the mouse neuromuscular junction. ARs and the presynaptic muscarinic acetylcholine receptors (mAChRs) share the functional control of the neuromuscular junction. We analysed their mutual interaction in transmitter release modulation. In electrophysiological experiments with unaltered synaptic transmission (muscles paralysed by blocking the voltage-dependent sodium channel of the muscle cells with μ-conotoxin GIIIB), we found that: (i) a collaborative action between different AR subtypes reduced synaptic depression at a moderate activity level (40 Hz); (ii) at high activity levels (100 Hz), endogenous adenosine production in the synaptic cleft was sufficient to reduce depression through A1 -type receptors (A1 Rs) and A2 A-type receptors (A2 A Rs); (iii) when the non-metabolizable 2-chloroadenosine (CADO) agonist was used, both the quantal content and depression were reduced; (iv) the protective effect of CADO on depression was mediated by A1 Rs, whereas A2 A Rs seemed to modulate A1 Rs; (v) ARs and mAChRs absolutely depended upon each other for the modulation of evoked and spontaneous acetylcholine release in basal conditions and in experimental conditions with CADO stimulation; (vi) the purinergic and muscarinic mechanisms cooperated in the control of depression by sharing a common pathway although the purinergic control was more powerful than the muscarinic control; and (vii) the imbalance of the ARs created by using subtype-selective and non-selective inhibitory and stimulatory agents uncoupled protein kinase C from evoked transmitter release. In summary, ARs (A1 Rs, A2 A Rs) and mAChRs (M1 , M2 ) cooperated in the control of activity-dependent synaptic depression and may share a common protein kinase C pathway.
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Affiliation(s)
- M M Santafe
- Unitat d'Histologia i Neurobiologia (UHN), Facultat de Medicina i Ciències de la Salut, Universitat Rovira i Virgili, carrer St Llorenç num 21, Reus, 43201, Spain
| | - M Priego
- Unitat d'Histologia i Neurobiologia (UHN), Facultat de Medicina i Ciències de la Salut, Universitat Rovira i Virgili, carrer St Llorenç num 21, Reus, 43201, Spain
| | - T Obis
- Unitat d'Histologia i Neurobiologia (UHN), Facultat de Medicina i Ciències de la Salut, Universitat Rovira i Virgili, carrer St Llorenç num 21, Reus, 43201, Spain
| | - N Garcia
- Unitat d'Histologia i Neurobiologia (UHN), Facultat de Medicina i Ciències de la Salut, Universitat Rovira i Virgili, carrer St Llorenç num 21, Reus, 43201, Spain
| | - M Tomàs
- Unitat d'Histologia i Neurobiologia (UHN), Facultat de Medicina i Ciències de la Salut, Universitat Rovira i Virgili, carrer St Llorenç num 21, Reus, 43201, Spain
| | - M A Lanuza
- Unitat d'Histologia i Neurobiologia (UHN), Facultat de Medicina i Ciències de la Salut, Universitat Rovira i Virgili, carrer St Llorenç num 21, Reus, 43201, Spain
| | - J Tomàs
- Unitat d'Histologia i Neurobiologia (UHN), Facultat de Medicina i Ciències de la Salut, Universitat Rovira i Virgili, carrer St Llorenç num 21, Reus, 43201, Spain
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Garção P, Szabó EC, Wopereis S, Castro AA, Tomé ÂR, Prediger RD, Cunha RA, Agostinho P, Köfalvi A. Functional interaction between pre-synaptic α6β2-containing nicotinic and adenosine A2A receptors in the control of dopamine release in the rat striatum. Br J Pharmacol 2014; 169:1600-11. [PMID: 23638679 DOI: 10.1111/bph.12234] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2012] [Revised: 04/17/2013] [Accepted: 04/19/2013] [Indexed: 12/21/2022] Open
Abstract
BACKGROUND AND PURPOSE Pre-synaptic nicotinic ACh receptors (nAChRs) and adenosine A2A receptors (A2A Rs) are involved in the control of dopamine release and are putative therapeutic targets in Parkinson's disease and addiction. Since A2A Rs have been reported to interact with nAChRs, here we aimed at mapping the possible functional interaction between A2A Rs and nAChRs in rat striatal dopaminergic terminals. EXPERIMENTAL APPROACH We pharmacologically characterized the release of dopamine and defined the localization of nAChR subunits in rat striatal nerve terminals in vitro and carried out locomotor behavioural sensitization in rats in vivo. KEY RESULTS In striatal nerve terminals, the selective A2A R agonist CGS21680 inhibited, while the A2A R antagonist ZM241385 potentiated the nicotine-stimulated [(3) H]dopamine ([(3) H]DA) release. Upon blockade of the α6 subunit-containing nAChRs, the remaining nicotine-stimulated [(3) H]DA release was no longer modulated by A2A R ligands. In the locomotor sensitization experiments, nicotine enhanced the locomotor activity on day 7 of repeated nicotine injection, an effect that no longer persisted after 1 week of drug withdrawal. Notably, ZM241385-injected rats developed locomotor sensitization to nicotine already on day 2, which remained persistent upon nicotine withdrawal. CONCLUSIONS AND IMPLICATIONS These results provide the first evidence for a functional interaction between nicotinic and adenosine A2A R in striatal dopaminergic terminals, with likely therapeutic consequences for smoking, Parkinson's disease and other dopaminergic disorders.
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Affiliation(s)
- P Garção
- Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal; Faculty of Medicine, University of Coimbra, Coimbra, Portugal
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Changeux JP. The concept of allosteric modulation: an overview. DRUG DISCOVERY TODAY. TECHNOLOGIES 2014; 10:e223-8. [PMID: 24050272 DOI: 10.1016/j.ddtec.2012.07.007] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
A brief historical overview of the concept of allosteric interaction is presented together with the different kinds of allosteric control recognized, in the past decades, with the model system of pentameric ligandgated ion channels. Multiple levels of allosteric modulation are identified that include sites distributed in the extracellular ligand binding domain (e.g. Ca2+ or benzodiazepines), the transmembrane domain (e.g. general anesthetic and various allosteric modulators) and the cytoplasmic domain, as potential targets for drug design. The new opportunities offered by the recent technological developments are discussed.
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Yoon JY, Jung SR, Hille B, Koh DS. Modulation of nicotinic receptor channels by adrenergic stimulation in rat pinealocytes. Am J Physiol Cell Physiol 2014; 306:C726-35. [PMID: 24553185 DOI: 10.1152/ajpcell.00354.2013] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Melatonin secretion from the pineal gland is triggered by norepinephrine released from sympathetic terminals at night. In contrast, cholinergic and parasympathetic inputs, by activating nicotinic cholinergic receptors (nAChR), have been suggested to counterbalance the noradrenergic input. Here we investigated whether adrenergic signaling regulates nAChR channels in rat pinealocytes. Acetylcholine or the selective nicotinic receptor agonist 1,1-dimethyl-4-phenylpiperazinium iodide (DMPP) activated large nAChR currents in whole cell patch-clamp experiments. Norepinephrine (NE) reduced the nAChR currents, an effect partially mimicked by a β-adrenergic receptor agonist, isoproterenol, and blocked by a β-adrenergic receptor antagonist, propranolol. Increasing intracellular cAMP levels using membrane-permeable 8-bromoadenosine (8-Br)-cAMP or 5,6-dichlorobenzimidazole riboside-3',5'-cyclic monophosphorothioate (cBIMPS) also reduced nAChR activity, mimicking the effects of NE and isoproterenol. Further, removal of ATP from the intracellular pipette solution blocked the reduction of nAChR currents, suggesting involvement of protein kinases. Indeed protein kinase A inhibitors, H-89 and Rp-cAMPS, blocked the modulation of nAChR by adrenergic stimulation. After the downmodulation by NE, nAChR channels mediated a smaller Ca(2+) influx and less membrane depolarization from the resting potential. Together these results suggest that NE released from sympathetic terminals at night attenuates nicotinic cholinergic signaling.
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Affiliation(s)
- Jin-Young Yoon
- Department of Physiology and Biophysics, University of Washington, Seattle, Washington; and
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Metaxas A, Al-Hasani R, Farshim P, Tubby K, Berwick A, Ledent C, Hourani S, Kitchen I, Bailey A. Genetic deletion of the adenosine A(2A) receptor prevents nicotine-induced upregulation of α7, but not α4β2* nicotinic acetylcholine receptor binding in the brain. Neuropharmacology 2013; 71:228-36. [PMID: 23583933 DOI: 10.1016/j.neuropharm.2013.03.023] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2013] [Revised: 03/11/2013] [Accepted: 03/22/2013] [Indexed: 10/27/2022]
Abstract
Considerable evidence indicates that adenosine A(2A) receptors (A(2A)Rs) modulate cholinergic neurotransmission, nicotinic acetylcholine receptor (nAChR) function, and nicotine-induced behavioural effects. To explore the interaction between A(2A) and nAChRs, we examined if the complete genetic deletion of adenosine A(2A)Rs in mice induces compensatory alterations in the binding of different nAChR subtypes, and whether the long-term effects of nicotine on nAChR regulation are altered in the absence of the A(2A)R gene. Quantitative autoradiography was used to measure cytisine-sensitive [¹²⁵I]epibatidine and [¹²⁵I]α-bungarotoxin binding to α4β2* and α7 nAChRs, respectively, in brain sections of drug-naïve (n = 6) or nicotine treated (n = 5-7), wild-type and adenosine A(2A)R knockout mice. Saline or nicotine (7.8 mg/kg/day; free-base weight) were administered to male CD1 mice via subcutaneous osmotic minipumps for a period of 14 days. Blood plasma levels of nicotine and cotinine were measured at the end of treatment. There were no compensatory developmental alterations in nAChR subtype distribution or density in drug-naïve A(2A)R knockout mice. In nicotine treated wild-type mice, both α4β2* and α7 nAChR binding sites were increased compared with saline treated controls. The genetic ablation of adenosine A(2A)Rs prevented nicotine-induced upregulation of α7 nAChRs, without affecting α4β2* receptor upregulation. This selective effect was observed at plasma levels of nicotine that were within the range reported for smokers (10-50 ng ml⁻¹). Our data highlight the involvement of adenosine A(2A)Rs in the mechanisms of nicotine-induced α7 nAChR upregulation, and identify A(2A)Rs as novel pharmacological targets for modulating the long-term effects of nicotine on α7 receptors.
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Affiliation(s)
- Athanasios Metaxas
- Sleep, Chronobiology & Addiction Group, Department of Biochemistry & Physiology, Faculty of Health and Medical Sciences, Institute of Health & Medical Sciences, University of Surrey, UK.
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Deflorio C, Palma E, Conti L, Roseti C, Manteca A, Giacomelli E, Catalano M, Limatola C, Inghilleri M, Grassi F. Riluzole blocks human muscle acetylcholine receptors. J Physiol 2012; 590:2519-28. [PMID: 22431338 DOI: 10.1113/jphysiol.2012.230201] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Riluzole, the only drug available against amyotrophic lateral sclerosis (ALS), has recently been shown to block muscle ACh receptors (AChRs), raising concerns about possible negative side-effects on neuromuscular transmission in treated patients. In this work we studied riluzole's impact on the function of muscle AChRs in vitro and on neuromuscular transmission in ALS patients, using electrophysiological techniques. Human recombinant AChRs composed of α(1)β(1)δ subunits plus the γ or ε subunit (γ- or ε-AChR) were expressed in HEK cells or Xenopus oocytes. In both preparations, riluzole at 0.5 μm, a clinically relevant concentration, reversibly reduced the amplitude and accelerated the decay of ACh-evoked current if applied before coapplication with ACh. The action on γ-AChRs was more potent and faster than on ε-AChRs. In HEK outside-out patches, riluzole-induced block of macroscopic ACh-evoked current gradually developed during the initial milliseconds of ACh presence. Single channel recordings in HEK cells and in human myotubes from ALS patients showed that riluzole prolongs channel closed time, but has no effect on channel conductance and open duration. Finally, compound muscle action potentials (CMAPs) evoked by nerve stimulation in ALS patients remained unaltered after a 1 week suspension of riluzole treatment. These data indicate that riluzole, while apparently safe with regard to synaptic transmission, may affect the function of AChRs expressed in denervated muscle fibres of ALS patients, with biological consequences that remain to be investigated.
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Affiliation(s)
- Cristina Deflorio
- Department of Physiology and Pharmacology, Sapienza University, Rome, Italy
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