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Whiteaker P, George AA. Discoveries and future significance of research into amyloid-beta/α7-containing nicotinic acetylcholine receptor (nAChR) interactions. Pharmacol Res 2023; 191:106743. [PMID: 37084859 DOI: 10.1016/j.phrs.2023.106743] [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: 12/15/2022] [Revised: 03/13/2023] [Accepted: 03/21/2023] [Indexed: 04/23/2023]
Abstract
Initiated by findings that Alzheimer's disease is associated with a profound loss of cholinergic markers in human brain, decades of studies have examined the interactions between specific subtypes of nicotinic acetylcholine receptors and amyloid-β [derive from the amyloid precursor protein (APP), which is cleaved to yield variable isoforms of amyloid-β]. We review the evolving understanding of amyloid-β's roles in Alzheimer's disease and pioneering studies that highlighted a role of nicotinic acetylcholine receptors in mediating important aspects of amyloid-β's effects. This review also surveys the current state of research into amyloid-β / nicotinic acetylcholine receptor interactions. The field has reached an exciting point in which common themes are emerging from the wide range of prior research and a range of accessible, relevant model systems are available to drive further progress. We highlight exciting new areas of inquiry and persistent challenges that need to be considered while conducting this research. Studies of amyloid-β and nicotinic acetylcholine receptor populations that it interacts with provide opportunities for innovative basic and translational scientific breakthroughs related to nicotinic receptors biology, Alzheimer's disease, and cholinergic contributions to cognition more broadly.
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Affiliation(s)
- Paul Whiteaker
- Virginia Commonwealth University School of Medicine, Department of Pharmacology and Toxicology, VCU Health Sciences Research Building, Box 980613, Richmond, VA 23298-0613, USA
| | - Andrew A George
- Virginia Commonwealth University School of Medicine, Department of Pharmacology and Toxicology, VCU Health Sciences Research Building, Box 980613, Richmond, VA 23298-0613, USA.
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2
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Jin XT, Drenan RM. Functional α7 nicotinic acetylcholine receptors in GABAergic neurons of the interpeduncular nucleus. Neuropharmacology 2022; 208:108987. [PMID: 35167902 PMCID: PMC8885883 DOI: 10.1016/j.neuropharm.2022.108987] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2021] [Revised: 02/02/2022] [Accepted: 02/05/2022] [Indexed: 11/17/2022]
Abstract
The interpeduncular nucleus (IPN) plays a key role in nicotine dependence and is involved in regulation of fear responses, affective states, and novelty processing. IPN neurons express nicotinic acetylcholine receptors (nAChR) and receive strong cholinergic innervation from the ventral medial habenula. Dorsal medial habenula neurons are primarily peptidergic, releasing substance P (SP) mainly onto IPN neurons in the lateral subnucleus (IPL). IPL neurons are sensitive to SP, but it is not known if they are involved in cholinergic transmission like other IPN neurons. We examined nAChR subunit gene expression in IPL neurons, revealing that Chrna7 (α7 nAChR subunit) is expressed in a subset of GABAergic IPL neurons. In patch-clamp recordings from IPL neurons, ACh-evoked inward currents were attenuated by methyllycaconitine (α7 nAChR antagonist) and potentiated by NS1738 (α7 Type I positive allosteric modulator). We confirmed α7 functional expression in IPL neurons by also showing that ACh-evoked currents were potentiated by PNU-120596 (Type II positive allosteric modulator). Additional pharmacological experiments show that IPN neurons expressing α7 nAChRs also express α3β4 nAChRs. Finally, we used 2-photon laser scanning microscopy and nicotine uncaging to directly examine the morphology of IPL neurons that express α7 nAChRs. These results highlight a novel aspect of α7 nAChR neurobiology, adding to the complexity of cholinergic modulation by nAChRs in the IPN.
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Affiliation(s)
- Xiao-Tao Jin
- Department of Physiology & Pharmacology, Wake Forest University School of Medicine, Winston-Salem, NC, USA
| | - Ryan M Drenan
- Department of Physiology & Pharmacology, Wake Forest University School of Medicine, Winston-Salem, NC, USA.
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Meganathan K, Prakasam R, Baldridge D, Gontarz P, Zhang B, Urano F, Bonni A, Maloney SE, Turner TN, Huettner JE, Constantino JN, Kroll KL. Altered neuronal physiology, development, and function associated with a common chromosome 15 duplication involving CHRNA7. BMC Biol 2021; 19:147. [PMID: 34320968 PMCID: PMC8317352 DOI: 10.1186/s12915-021-01080-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2021] [Accepted: 06/30/2021] [Indexed: 01/05/2023] Open
Abstract
BACKGROUND Copy number variants (CNVs) linked to genes involved in nervous system development or function are often associated with neuropsychiatric disease. While CNVs involving deletions generally cause severe and highly penetrant patient phenotypes, CNVs leading to duplications tend instead to exhibit widely variable and less penetrant phenotypic expressivity among affected individuals. CNVs located on chromosome 15q13.3 affecting the alpha-7 nicotinic acetylcholine receptor subunit (CHRNA7) gene contribute to multiple neuropsychiatric disorders with highly variable penetrance. However, the basis of such differential penetrance remains uncharacterized. Here, we generated induced pluripotent stem cell (iPSC) models from first-degree relatives with a 15q13.3 duplication and analyzed their cellular phenotypes to uncover a basis for the dissimilar phenotypic expressivity. RESULTS The first-degree relatives studied included a boy with autism and emotional dysregulation (the affected proband-AP) and his clinically unaffected mother (UM), with comparison to unrelated control models lacking this duplication. Potential contributors to neuropsychiatric impairment were modeled in iPSC-derived cortical excitatory and inhibitory neurons. The AP-derived model uniquely exhibited disruptions of cellular physiology and neurodevelopment not observed in either the UM or unrelated controls. These included enhanced neural progenitor proliferation but impaired neuronal differentiation, maturation, and migration, and increased endoplasmic reticulum (ER) stress. Both the neuronal migration deficit and elevated ER stress could be selectively rescued by different pharmacologic agents. Neuronal gene expression was also dysregulated in the AP, including reduced expression of genes related to behavior, psychological disorders, neuritogenesis, neuronal migration, and Wnt, axonal guidance, and GABA receptor signaling. The UM model instead exhibited upregulated expression of genes in many of these same pathways, suggesting that molecular compensation could have contributed to the lack of neurodevelopmental phenotypes in this model. However, both AP- and UM-derived neurons exhibited shared alterations of neuronal function, including increased action potential firing and elevated cholinergic activity, consistent with increased homomeric CHRNA7 channel activity. CONCLUSIONS These data define both diagnosis-associated cellular phenotypes and shared functional anomalies related to CHRNA7 duplication that may contribute to variable phenotypic penetrance in individuals with 15q13.3 duplication. The capacity for pharmacological agents to rescue some neurodevelopmental anomalies associated with diagnosis suggests avenues for intervention for carriers of this duplication and other CNVs that cause related disorders.
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Affiliation(s)
- Kesavan Meganathan
- Department of Developmental Biology, Washington University School of Medicine, 660 S. Euclid Avenue, Campus, Box 8103, St. Louis, MO 63110 USA
| | - Ramachandran Prakasam
- Department of Developmental Biology, Washington University School of Medicine, 660 S. Euclid Avenue, Campus, Box 8103, St. Louis, MO 63110 USA
| | - Dustin Baldridge
- Department of Pediatrics, Washington University School of Medicine, St. Louis, MO 63110 USA
| | - Paul Gontarz
- Department of Developmental Biology, Washington University School of Medicine, 660 S. Euclid Avenue, Campus, Box 8103, St. Louis, MO 63110 USA
| | - Bo Zhang
- Department of Developmental Biology, Washington University School of Medicine, 660 S. Euclid Avenue, Campus, Box 8103, St. Louis, MO 63110 USA
| | - Fumihiko Urano
- Department of Medicine, Division of Endocrinology, Washington University School of Medicine, St. Louis, MO 63110 USA
| | - Azad Bonni
- Department of Neuroscience, Washington University School of Medicine, St. Louis, MO 63110 USA
| | - Susan E. Maloney
- Department of Psychiatry, Washington University School of Medicine, St. Louis, MO 63110 USA
| | - Tychele N. Turner
- Department of Genetics, Washington University School of Medicine, St. Louis, MO 63110 USA
| | - James E. Huettner
- Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, MO 63110 USA
| | - John N. Constantino
- Department of Psychiatry, Washington University School of Medicine, St. Louis, MO 63110 USA
| | - Kristen L. Kroll
- Department of Developmental Biology, Washington University School of Medicine, 660 S. Euclid Avenue, Campus, Box 8103, St. Louis, MO 63110 USA
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Ågren R, Zeberg H. Low-Resistance silver bromide electrodes for recording fast ion channel kinetics under voltage clamp conditions. J Neurosci Methods 2020; 348:108984. [PMID: 33164817 DOI: 10.1016/j.jneumeth.2020.108984] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2020] [Revised: 10/14/2020] [Accepted: 10/20/2020] [Indexed: 10/23/2022]
Abstract
BACKGROUND Two-electrode voltage clamp is a widely used technique for studying ionic currents. However, fast activation kinetics of ion channels are disguised by the capacitive transient during voltage clamp of Xenopus oocytes. The limiting factors of clamp performance include, but are not limited to, amplifier gain, membrane capacitance, and micropipette resistance. Previous work has focused on increasing amplifier gain (e.g.; high performing two-electrode amplifiers) or reducing the membrane capacitance (e.g.; the cut-open technique). NEW METHOD The use of an Ag-AgBr electrode with saturated KBr solution to reduce micropipette resistance. RESULTS The conductivity of 4 M KBr was 37 % higher compared to 3 M KCl and the micropipette resistance was reduced by 19 % when 4 M KBr was used, compared to the standard 3 M KCl solution. Micropipette resistances correlated positively with capacitive transient durations. Neither the current-voltage relationship of the voltage-gated sodium channel, Nav1.7, nor Xenopus oocyte stability were affected by bromide ions. COMPARISON WITH EXISTING METHODS The de facto standard for two-electrode voltage clamp is 3 M KCl and Ag-AgCl electrodes, which are associated an unnecessarily high micropipette resistance. Elsewise, cut-open voltage clamp techniques are technically demanding and require manipulation of the intracellular environment. CONCLUSIONS The use of an Ag-AgBr electrode with saturated KBr as micropipette solution reduces the capacitive transient in two-electrode voltage clamp recordings. Moreover, the exchange of chloride against bromide ions does not seem to affect oocyte physiology and ion channel kinetics.
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Affiliation(s)
- Richard Ågren
- Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden.
| | - Hugo Zeberg
- Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden
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Donat CK, Hansen HH, Hansen HD, Mease RC, Horti AG, Pomper MG, L’Estrade ET, Herth MM, Peters D, Knudsen GM, Mikkelsen JD. In Vitro and In Vivo Characterization of Dibenzothiophene Derivatives [ 125I]Iodo-ASEM and [ 18F]ASEM as Radiotracers of Homo- and Heteromeric α7 Nicotinic Acetylcholine Receptors. Molecules 2020; 25:molecules25061425. [PMID: 32245032 PMCID: PMC7144377 DOI: 10.3390/molecules25061425] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2020] [Revised: 02/25/2020] [Accepted: 02/27/2020] [Indexed: 12/18/2022] Open
Abstract
The α7 nicotinic acetylcholine receptor (α7 nAChR) is involved in several cognitive and physiologic processes; its expression levels and patterns change in neurologic and psychiatric diseases, such as schizophrenia and Alzheimer’s disease, which makes it a relevant drug target. Development of selective radioligands is important for defining binding properties and occupancy of novel molecules targeting the receptor. We tested the in vitro binding properties of [125I]Iodo-ASEM [(3-(1,4-diazabycyclo[3.2.2]nonan-4-yl)-6-(125I-iododibenzo[b,d]thiopentene 5,5-dioxide)] in the mouse, rat and pig brain using autoradiography. The in vivo binding properties of [18F]ASEM were investigated using positron emission tomography (PET) in the pig brain. [125I]Iodo-ASEM showed specific and displaceable high affinity (~1 nM) binding in mouse, rat, and pig brain. Binding pattern overlapped with [125I]α-bungarotoxin, specific binding was absent in α7 nAChR gene-deficient mice and binding was blocked by a range of α7 nAChR orthosteric modulators in an affinity-dependent order in the pig brain. Interestingly, relative to the wild-type, binding in β2 nAChR gene-deficient mice was lower for [125I]Iodo-ASEM (58% ± 2.7%) than [125I]α-bungarotoxin (23% ± 0.2%), potentially indicating different binding properties to heteromeric α7β2 nAChR. [18F]ASEM PET in the pig showed high brain uptake and reversible tracer kinetics with a similar spatial distribution as previously reported for α7 nAChR. Blocking with SSR-180,711 resulted in a significant decrease in [18F]ASEM binding. Our findings indicate that [125I]Iodo-ASEM allows sensitive and selective imaging of α7 nAChR in vitro, with better signal-to-noise ratio than previous tracers. Preliminary data of [18F]ASEM in the pig brain demonstrated principal suitable kinetic properties for in vivo quantification of α7 nAChR, comparable to previously published data.
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Affiliation(s)
- Cornelius K. Donat
- Neurobiology Research Unit, Copenhagen University Hospital, Rigshospitalet, DK-2100 Copenhagen, Denmark; (H.H.H.); (H.D.H.); (E.T.L.); (G.M.K.)
- Department of Brain Sciences, Imperial College London, London W12 0 LS, UK
- Correspondence: (C.K.D.); (J.D.M.); Tel.: +45-40205378 (J.D.M)
| | - Henrik H. Hansen
- Neurobiology Research Unit, Copenhagen University Hospital, Rigshospitalet, DK-2100 Copenhagen, Denmark; (H.H.H.); (H.D.H.); (E.T.L.); (G.M.K.)
| | - Hanne D. Hansen
- Neurobiology Research Unit, Copenhagen University Hospital, Rigshospitalet, DK-2100 Copenhagen, Denmark; (H.H.H.); (H.D.H.); (E.T.L.); (G.M.K.)
| | - Ronnie C. Mease
- Russell H. Morgan Department of Radiology and Radiological Science, The Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA; (R.C.M.); (A.G.H.); (M.G.P.)
| | - Andrew G. Horti
- Russell H. Morgan Department of Radiology and Radiological Science, The Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA; (R.C.M.); (A.G.H.); (M.G.P.)
| | - Martin G. Pomper
- Russell H. Morgan Department of Radiology and Radiological Science, The Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA; (R.C.M.); (A.G.H.); (M.G.P.)
| | - Elina T. L’Estrade
- Neurobiology Research Unit, Copenhagen University Hospital, Rigshospitalet, DK-2100 Copenhagen, Denmark; (H.H.H.); (H.D.H.); (E.T.L.); (G.M.K.)
- Department of Drug Design and Pharmacology, University of Copenhagen, Jagtvej 162, 2100 Copenhagen, Denmark;
- Department of Clinical Physiology, Nuclear Medicine & PET, Rigshospitalet, Blegdamsvej 9, 2100 Copenhagen, Denmark
| | - Matthias M. Herth
- Department of Drug Design and Pharmacology, University of Copenhagen, Jagtvej 162, 2100 Copenhagen, Denmark;
- Department of Clinical Physiology, Nuclear Medicine & PET, Rigshospitalet, Blegdamsvej 9, 2100 Copenhagen, Denmark
| | | | - Gitte M. Knudsen
- Neurobiology Research Unit, Copenhagen University Hospital, Rigshospitalet, DK-2100 Copenhagen, Denmark; (H.H.H.); (H.D.H.); (E.T.L.); (G.M.K.)
| | - Jens D. Mikkelsen
- Neurobiology Research Unit, Copenhagen University Hospital, Rigshospitalet, DK-2100 Copenhagen, Denmark; (H.H.H.); (H.D.H.); (E.T.L.); (G.M.K.)
- Correspondence: (C.K.D.); (J.D.M.); Tel.: +45-40205378 (J.D.M)
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Kimura I, Dohgu S, Takata F, Matsumoto J, Kawahara Y, Nishihira M, Sakada S, Saisho T, Yamauchi A, Kataoka Y. Activation of the α7 nicotinic acetylcholine receptor upregulates blood-brain barrier function through increased claudin-5 and occludin expression in rat brain endothelial cells. Neurosci Lett 2019; 694:9-13. [DOI: 10.1016/j.neulet.2018.11.022] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2018] [Revised: 11/12/2018] [Accepted: 11/14/2018] [Indexed: 10/27/2022]
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Chen YQ, Wang Z, Wu Y, Wisniewski SR, Qiao JX, Ewing WR, Eastgate MD, Yu JQ. Overcoming the Limitations of γ- and δ-C–H Arylation of Amines through Ligand Development. J Am Chem Soc 2018; 140:17884-17894. [DOI: 10.1021/jacs.8b07109] [Citation(s) in RCA: 125] [Impact Index Per Article: 20.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Affiliation(s)
- Yan-Qiao Chen
- Department of Chemistry, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Zhen Wang
- Department of Chemistry, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Yongwei Wu
- Department of Chemistry, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Steven R. Wisniewski
- Chemical & Synthetic Development, Bristol-Myers Squibb, 1 Squibb Drive, New Brunswick, New Jersey 08903, United States
| | - Jennifer X. Qiao
- Discovery Chemistry, Bristol-Myers Squibb, PO Box 4000, Princeton, New Jersey 08543, United States
| | - William R. Ewing
- Discovery Chemistry, Bristol-Myers Squibb, PO Box 4000, Princeton, New Jersey 08543, United States
| | - Martin D. Eastgate
- Chemical & Synthetic Development, Bristol-Myers Squibb, 1 Squibb Drive, New Brunswick, New Jersey 08903, United States
| | - Jin-Quan Yu
- Department of Chemistry, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, United States
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Nielsen BE, Minguez T, Bermudez I, Bouzat C. Molecular function of the novel α7β2 nicotinic receptor. Cell Mol Life Sci 2018; 75:2457-2471. [PMID: 29313059 PMCID: PMC11105712 DOI: 10.1007/s00018-017-2741-4] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2017] [Revised: 11/30/2017] [Accepted: 12/27/2017] [Indexed: 01/03/2023]
Abstract
The α7 nicotinic receptor is a promising drug target for neurological and inflammatory disorders. Although it is the homomeric member of the family, a novel α7β2 heteromeric receptor has been discovered. To decipher the functional contribution of the β2 subunit, we generated heteromeric receptors with fixed stoichiometry by two different approaches comprising concatenated and unlinked subunits. Receptors containing up to three β2 subunits are functional. As the number of β2 subunits increases in the pentameric arrangement, the durations of channel openings and activation episodes increase progressively probably due to decreased desensitization. The prolonged activation episodes conform the kinetic signature of α7β2 and may have an impact on neuronal excitability. For activation of α7β2 receptors, an α7/α7 binding-site interface is required, thus indicating that the three β2 subunits are located consecutively in the pentameric arrangement. α7-positive allosteric modulators (PAMs) are emerging as novel therapeutic drugs. The presence of β2 in the pentamer affects neither type II PAM potentiation nor activation by an allosteric agonist whereas it impairs type I PAM potentiation. This first single-channel study provides fundamental basis required to decipher the role and function of the novel α7β2 receptor and opens doors to develop selective therapeutic drugs.
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Affiliation(s)
- Beatriz E Nielsen
- Instituto de Investigaciones Bioquímicas de Bahía Blanca, Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur-Consejo Nacional de Investigaciones Científicas y Técnicas (UNS-CONICET), 8000, Bahía Blanca, Argentina
| | - Teresa Minguez
- Department of Medical and Biological Sciences, Oxford Brookes University, Oxford, OX3 0BP, UK
| | - Isabel Bermudez
- Department of Medical and Biological Sciences, Oxford Brookes University, Oxford, OX3 0BP, UK
| | - 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 (UNS-CONICET), 8000, Bahía Blanca, Argentina.
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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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Fujii T, Mashimo M, Moriwaki Y, Misawa H, Ono S, Horiguchi K, Kawashima K. Expression and Function of the Cholinergic System in Immune Cells. Front Immunol 2017; 8:1085. [PMID: 28932225 PMCID: PMC5592202 DOI: 10.3389/fimmu.2017.01085] [Citation(s) in RCA: 217] [Impact Index Per Article: 31.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2017] [Accepted: 08/21/2017] [Indexed: 12/29/2022] Open
Abstract
T and B cells express most cholinergic system components—e.g., acetylcholine (ACh), choline acetyltransferase (ChAT), acetylcholinesterase, and both muscarinic and nicotinic ACh receptors (mAChRs and nAChRs, respectively). Using ChATBAC-eGFP transgenic mice, ChAT expression has been confirmed in T and B cells, dendritic cells, and macrophages. Moreover, T cell activation via T-cell receptor/CD3-mediated pathways upregulates ChAT mRNA expression and ACh synthesis, suggesting that this lymphocytic cholinergic system contributes to the regulation of immune function. Immune cells express all five mAChRs (M1–M5). Combined M1/M5 mAChR-deficient (M1/M5-KO) mice produce less antigen-specific antibody than wild-type (WT) mice. Furthermore, spleen cells in M1/M5-KO mice produce less tumor necrosis factor (TNF)-α and interleukin (IL)-6, suggesting M1/M5 mAChRs are involved in regulating pro-inflammatory cytokine and antibody production. Immune cells also frequently express the α2, α5, α6, α7, α9, and α10 nAChR subunits. α7 nAChR-deficient (α7-KO) mice produce more antigen-specific antibody than WT mice, and spleen cells from α7-KO mice produce more TNF-α and IL-6 than WT cells. This suggests that α7 nAChRs are involved in regulating cytokine production and thus modulate antibody production. Evidence also indicates that nicotine modulates immune responses by altering cytokine production and that α7 nAChR signaling contributes to immunomodulation through modification of T cell differentiation. Together, these findings suggest the involvement of both mAChRs and nAChRs in the regulation of immune function. The observation that vagus nerve stimulation protects mice from lethal endotoxin shock led to the notion of a cholinergic anti-inflammatory reflex pathway, and the spleen is an essential component of this anti-inflammatory reflex. Because the spleen lacks direct vagus innervation, it has been postulated that ACh synthesized by a subset of CD4+ T cells relays vagal nerve signals to α7 nAChRs on splenic macrophages, which downregulates TNF-α synthesis and release, thereby modulating inflammatory responses. However, because the spleen is innervated solely by the noradrenergic splenic nerve, confirmation of an anti-inflammatory reflex pathway involving the spleen requires several more hypotheses to be addressed. We will review and discuss these issues in the context of the cholinergic system in immune cells.
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Affiliation(s)
- Takeshi Fujii
- Faculty of Pharmaceutical Sciences, Department of Pharmacology, Doshisha Women's College of Liberal Arts, Kyoto, Japan
| | - Masato Mashimo
- Faculty of Pharmaceutical Sciences, Department of Pharmacology, Doshisha Women's College of Liberal Arts, Kyoto, Japan
| | - Yasuhiro Moriwaki
- Faculty of Pharmacy, Department of Pharmacology, Keio University, Tokyo, Japan
| | - Hidemi Misawa
- Faculty of Pharmacy, Department of Pharmacology, Keio University, Tokyo, Japan
| | - Shiro Ono
- Laboratory of Immunology, Faculty of Pharmacy, Osaka Ohtani University, Osaka, Japan
| | - Kazuhide Horiguchi
- Department of Anatomy, Division of Medicine, University of Fukui Faculty of Medical Sciences, Fukui, Japan
| | - Koichiro Kawashima
- Department of Molecular Pharmacology, Kitasato University School of Pharmaceutical Sciences, Tokyo, Japan
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Fujii T, Mashimo M, Moriwaki Y, Misawa H, Ono S, Horiguchi K, Kawashima K. Physiological functions of the cholinergic system in immune cells. J Pharmacol Sci 2017; 134:1-21. [DOI: 10.1016/j.jphs.2017.05.002] [Citation(s) in RCA: 102] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2017] [Revised: 04/30/2017] [Accepted: 05/08/2017] [Indexed: 02/07/2023] Open
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Callahan PM, Bertrand D, Bertrand S, Plagenhoef MR, Terry AV. Tropisetron sensitizes α7 containing nicotinic receptors to low levels of acetylcholine in vitro and improves memory-related task performance in young and aged animals. Neuropharmacology 2017; 117:422-433. [PMID: 28259598 DOI: 10.1016/j.neuropharm.2017.02.025] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2016] [Revised: 02/06/2017] [Accepted: 02/25/2017] [Indexed: 01/02/2023]
Abstract
Tropisetron, a 5-HT3 receptor antagonist commonly prescribed for chemotherapy-induced nausea and vomiting also exhibits high affinity, partial agonist activity at α7 nicotinic acetylcholine receptors (α7 nAChRs). α7 nAChRs are considered viable therapeutic targets for neuropsychiatric disorders such as Alzheimer's disease (AD). Here we further explored the nAChR pharmacology of tropisetron to include the homomeric α7 nAChR and recently characterized heteromeric α7β2 nAChR (1:10 ratio) and we evaluated its cognitive effects in young and aged animals. Electrophysiological studies on human nAChRs expressed in Xenopus oocytes confirmed the partial agonist activity of tropisetron at α7 nAChRs (EC50 ∼2.4 μM) with a similar effect at α7β2 nAChRs (EC50 ∼1.5 μM). Moreover, currents evoked by irregular pulses of acetylcholine (40 μM) at α7 and α7β2 nAChRs were enhanced during sustained exposure to low concentrations of tropisetron (10 and 30 nM) indicative of a "priming" or co-agonist effect. Tropisetron (0.1-10 mg/kg) improved novel object recognition performance in young Sprague-Dawley rats and in aged Fischer rats. In aged male and female rhesus monkeys, tropisetron (0.03-1 mg/kg) produced a 17% increase from baseline levels in delayed match to sample long delay accuracy while combination of non-effective doses of donepezil (0.1 mg/kg) and tropisetron (0.03 and 0.1 mg/kg) produced a 24% change in accuracy. Collectively, these animal experiments indicate that tropisetron enhances cognition and has the ability to improve the effective dose range of currently prescribed AD therapy (donepezil). Moreover, these effects may be explained by tropisetron's ability to sensitize α7 containing nAChRs to low levels of acetylcholine.
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Affiliation(s)
- Patrick M Callahan
- Department of Pharmacology and Toxicology, Augusta University, Augusta, GA 30912, United States.
| | - Daniel Bertrand
- HiQScreen Sàrl, 6, rte de Compois, 1222 Vésenaz, Geneva, Switzerland
| | - Sonia Bertrand
- HiQScreen Sàrl, 6, rte de Compois, 1222 Vésenaz, Geneva, Switzerland
| | - Marc R Plagenhoef
- Department of Pharmacology and Toxicology, Augusta University, Augusta, GA 30912, United States
| | - Alvin V Terry
- Department of Pharmacology and Toxicology, Augusta University, Augusta, GA 30912, United States
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13
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Mazzo F, Zwart R, Serratto GM, Gardinier KM, Porter W, Reel J, Maraula G, Sher E. Reconstitution of synaptic Ion channels from rodent and human brain in Xenopus oocytes: a biochemical and electrophysiological characterization. J Neurochem 2016; 138:384-96. [PMID: 27216696 DOI: 10.1111/jnc.13675] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2016] [Revised: 05/10/2016] [Accepted: 05/18/2016] [Indexed: 11/29/2022]
Abstract
Disruption in the expression and function of synaptic proteins, and ion channels in particular, is critical in the pathophysiology of human neuropsychiatric and neurodegenerative diseases. However, very little is known regarding the functional and pharmacological properties of native synaptic human ion channels, and their potential changes in pathological conditions. Recently, an electrophysiological technique has been enabled for studying the functional and pharmacological properties of ion channels present in crude membrane preparation obtained from post-mortem frozen brains. We here extend these studies by showing that human synaptic ion channels also can be studied in this way. Synaptosomes purified from different regions of rodent and human brain (control and Alzheimer's) were characterized biochemically for enrichment of synaptic proteins, and expression of ion channel subunits. The same synaptosomes were also reconstituted in Xenopus oocytes, in which the functional and pharmacological properties of the native synaptic ion channels were characterized using the voltage clamp technique. We show that we can detect GABA, (RS)-α-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid, and NMDA receptors, and modulate them pharmacologically with selective agonists, antagonists, and allosteric modulators. Furthermore, changes in ion channel expression and function were detected in synaptic membranes from Alzheimer's brains. Our present results demonstrate the possibility to investigate synaptic ion channels from healthy and pathological brains. This method of synaptosomes preparation and injection into oocytes is a significant improvement over the earlier method. It opens the way to directly testing, on native ion channels, the effects of novel drugs aimed at modulating important classes of synaptic targets. Disruption in the expression and function of synaptic ion channels is critical in the pathophysiology of human neurodegenerative diseases. We here show that synaptosomes purified from rodent and human frozen brain (control and Alzheimer disease) can be studied both biochemically and functionally. This method opens the way to directly testing the effects of novel drugs on native ion channels.
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Affiliation(s)
- Francesca Mazzo
- Lilly Research Centre, Eli Lilly and Company, Erl Wood Manor, Windlesham, Surrey, GU20 6HP, UK
| | - Ruud Zwart
- Lilly Research Centre, Eli Lilly and Company, Erl Wood Manor, Windlesham, Surrey, GU20 6HP, UK
| | - Giulia Maia Serratto
- Lilly Research Centre, Eli Lilly and Company, Erl Wood Manor, Windlesham, Surrey, GU20 6HP, UK
| | - Kevin M Gardinier
- Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, IN, 46285, USA
| | - Warren Porter
- Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, IN, 46285, USA
| | - Jon Reel
- Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, IN, 46285, USA
| | - Giovanna Maraula
- Lilly Research Centre, Eli Lilly and Company, Erl Wood Manor, Windlesham, Surrey, GU20 6HP, UK
| | - Emanuele Sher
- Lilly Research Centre, Eli Lilly and Company, Erl Wood Manor, Windlesham, Surrey, GU20 6HP, UK
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14
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Wu J, Liu Q, Tang P, Mikkelsen JD, Shen J, Whiteaker P, Yakel JL. Heteromeric α7β2 Nicotinic Acetylcholine Receptors in the Brain. Trends Pharmacol Sci 2016; 37:562-574. [PMID: 27179601 DOI: 10.1016/j.tips.2016.03.005] [Citation(s) in RCA: 64] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2016] [Revised: 03/27/2016] [Accepted: 03/30/2016] [Indexed: 10/21/2022]
Abstract
The α7 nicotinic acetylcholine receptor (α7 nAChR) is highly expressed in the brain, where it maintains various neuronal functions including (but not limited to) learning and memory. In addition, the protein expression levels of α7 nAChRs are altered in various brain disorders. The classic rule governing α7 nAChR assembly in the mammalian brain was that it was assembled from five α7 subunits to form a homomeric receptor pentamer. However, emerging evidence demonstrates the presence of heteromeric α7 nAChRs in heterologously expressed systems and naturally in brain neurons, where α7 subunits are co-assembled with β2 subunits to form a novel type of α7β2 nAChR. Interestingly, the α7β2 nAChR exhibits distinctive function and pharmacology from traditional homomeric α7 nAChRs. We review recent advances in probing the distribution, function, pharmacology, pathophysiology, and stoichiometry of the heteromeric α7β2 nAChR, which have provided new insights into the understanding of a novel target of cholinergic signaling.
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Affiliation(s)
- Jie Wu
- Department of Physiology, Shantou University Medicine College, Shantou, Guangdong, China; Divisions of Neurology and Neurobiology, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, AZ 85013-4496, USA.
| | - Qiang Liu
- Divisions of Neurology and Neurobiology, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, AZ 85013-4496, USA
| | - Pei Tang
- Department of Anesthesiology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15260, USA
| | - Jens D Mikkelsen
- Neurobiology Research Unit, University Hospital Copenhagen, Rigshospitalet, Copenhagen, Denmark
| | - Jianxin Shen
- Department of Physiology, Shantou University Medicine College, Shantou, Guangdong, China
| | - Paul Whiteaker
- Divisions of Neurology and Neurobiology, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, AZ 85013-4496, USA
| | - Jerrel L Yakel
- Neurobiology Laboratory, National Institute of Environmental Health Sciences (NIEHS), National Institutes of Health (NIH)/DHHS, Research Triangle Park, North Carolina 27709, USA
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15
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Bertrand D, Lee CHL, Flood D, Marger F, Donnelly-Roberts D. Therapeutic Potential of α7 Nicotinic Acetylcholine Receptors. Pharmacol Rev 2015; 67:1025-73. [DOI: 10.1124/pr.113.008581] [Citation(s) in RCA: 108] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
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Wallace TL, Bertrand D. Neuronal α7 Nicotinic Receptors as a Target for the Treatment of Schizophrenia. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2015; 124:79-111. [PMID: 26472526 DOI: 10.1016/bs.irn.2015.08.003] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Schizophrenia is a lifelong disease, the burden of which is often underestimated. Characterized by positive (e.g., hallucinations) and negative (e.g., avolition, amotivation) symptoms, schizophrenia is also accompanied with profound impairments in cognitive function that progress throughout the development of the disease. Although treatment with antipsychotic medications can effectively dampen some of the positive symptoms, these medications largely fail to reverse cognitive deficits or to mitigate negative symptoms. With a worldwide prevalence of approximately 1%, schizophrenia remains a large unmet medical need that stands to benefit greatly from (1) continued research to better understand the biological underpinnings of the disease and (2) the targeted development of novel therapeutics to improve the lives of those affected individuals. Improvements in our understanding of the neuronal networks associated with schizophrenia as well as progress in identifying genetic risk factors and environmental conditions that may predispose individuals to developing the disease are advancing new strategies to study and treat it. Herein, we review the evidence that supports the role of α7 nicotinic acetylcholine receptors in the central nervous system and why these receptors constitute a promising target to treat some of the prominent symptoms of schizophrenia.
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Ukrainets IV, Petrushova LA, Dzyubenko SP, Sim G, Grinevich LA. The Effective Synthesis of N-(Arylalkyl)-1-R-4-hydroxy-2,2-dioxo- 1H-2λ(6),1-benzothiazine-3-carboxamides as Promising Analgesics of a New Chemical Class. Sci Pharm 2015; 83:549-66. [PMID: 26839838 PMCID: PMC4727766 DOI: 10.3797/scipharm.1506-04] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2015] [Accepted: 07/17/2015] [Indexed: 11/22/2022] Open
Abstract
A new, effective preparative method has been proposed and the synthesis of a series of N-(arylalkyl)-1-R-4-hydroxy-2,2-dioxo-1H-2λ(6),1-benzothiazine-3-car-boxamides has been carried out. It has been shown that amidation of alkyl 1-R-4-hydroxy-2,2-dioxo-1H-2λ(6),1-benzothiazine-3-carboxylates with arylalkyl-amines in boiling xylene proceeds with good yield and purity to the corresponding N-(arylalkyl)-amides. However, the presence of water in the reaction mixture has been shown to cause the formation of specific impurities: N-(arylalkyl)-1-R-2,2-dioxo-1H-2λ(6),1-benzothiazin-4-amines. According to the results of the pharmacological studies, powerful analgesics have been found among the substances synthesized.
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Affiliation(s)
- Igor V Ukrainets
- Department of Pharmaceutical Chemistry, National University of Pharmacy, 53 Pushkinska St., 61002, Kharkiv, Ukraine
| | - Lidiya A Petrushova
- Department of Pharmaceutical Chemistry, National University of Pharmacy, 53 Pushkinska St., 61002, Kharkiv, Ukraine
| | - Sergiy P Dzyubenko
- Department of Pharmaceutical Chemistry, N. I. Pirogov Vinnitsa National Medical University, 56 Pirogov St., Vinnitsa, 21018, Ukraine
| | - Galina Sim
- Department of Pharmaceutical Chemistry, Far Eastern State Medical University, 35 Murav'eva-Amurskogo St., 680000, Khabarovsk, Russia
| | - Lina A Grinevich
- Department of Pharmaceutical Chemistry, National University of Pharmacy, 53 Pushkinska St., 61002, Kharkiv, Ukraine
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18
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Pharmacologically distinct nicotinic acetylcholine receptors drive efferent-mediated excitation in calyx-bearing vestibular afferents. J Neurosci 2015; 35:3625-43. [PMID: 25716861 DOI: 10.1523/jneurosci.3388-14.2015] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Electrical stimulation of vestibular efferent neurons rapidly excites the resting discharge of calyx/dimorphic (CD) afferents. In turtle, this excitation arises when acetylcholine (ACh), released from efferent terminals, directly depolarizes calyceal endings by activating nicotinic ACh receptors (nAChRs). Although molecular biological data from the peripheral vestibular system implicate most of the known nAChR subunits, specific information about those contributing to efferent-mediated excitation of CD afferents is lacking. We sought to identify the nAChR subunits that underlie the rapid excitation of CD afferents and whether they differ from α9α10 nAChRs on type II hair cells that drive efferent-mediated inhibition in adjacent bouton afferents. We recorded from CD and bouton afferents innervating the turtle posterior crista during electrical stimulation of vestibular efferents while applying several subtype-selective nAChR agonists and antagonists. The α9α10 nAChR antagonists, α-bungarotoxin and α-conotoxin RgIA, blocked efferent-mediated inhibition in bouton afferents while leaving efferent-mediated excitation in CD units largely intact. Conversely, 5-iodo-A-85380, sazetidine-A, varenicline, α-conotoxin MII, and bPiDDB (N,N-dodecane-1,12-diyl-bis-3-picolinium dibromide) blocked efferent-mediated excitation in CD afferents without affecting efferent-mediated inhibition in bouton afferents. This pharmacological profile suggested that calyceal nAChRs contain α6 and β2, but not α9, nAChR subunits. Selective blockade of efferent-mediated excitation in CD afferents distinguished dimorphic from calyx afferents by revealing type II hair cell input. Dimorphic afferents differed in having higher mean discharge rates and a mean efferent-mediated excitation that was smaller in amplitude yet longer in duration. Molecular biological data demonstrated the expression of α9 in turtle hair cells and α4 and β2 in associated vestibular ganglia.
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19
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Thomsen MS, Zwart R, Ursu D, Jensen MM, Pinborg LH, Gilmour G, Wu J, Sher E, Mikkelsen JD. α7 and β2 Nicotinic Acetylcholine Receptor Subunits Form Heteromeric Receptor Complexes that Are Expressed in the Human Cortex and Display Distinct Pharmacological Properties. PLoS One 2015; 10:e0130572. [PMID: 26086615 PMCID: PMC4472343 DOI: 10.1371/journal.pone.0130572] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2015] [Accepted: 05/21/2015] [Indexed: 12/03/2022] Open
Abstract
The existence of α7β2 nicotinic acetylcholine receptors (nAChRs) has recently been demonstrated in both the rodent and human brain. Since α7-containing nAChRs are promising drug targets for schizophrenia and Alzheimer’s disease, it is critical to determine whether α7β2 nAChRs are present in the human brain, in which brain areas, and whether they differ functionally from α7 nAChR homomers. We used α-bungarotoxin to affinity purify α7-containing nAChRs from surgically excised human temporal cortex, and found that α7 subunits co-purify with β2 subunits, indicating the presence of α7β2 nAChRs in the human brain. We validated these results by demonstrating co-purification of β2 from wild-type, but not α7 or β2 knock-out mice. The pharmacology and kinetics of human α7β2 nAChRs differed significantly from that of α7 homomers in response to nAChR agonists when expressed in Xenopus oocytes and HEK293 cells. Notably, α7β2 heteromers expressed in HEK293 cells display markedly slower rise and decay phases. These results demonstrate that α7 subunits in the human brain form heteromeric complexes with β2 subunits, and that human α7β2 nAChR heteromers respond to nAChR agonists with a unique pharmacology and kinetic profile. α7β2 nAChRs thus represent an alternative mechanism for the reported clinical efficacy of α7 nAChR ligands.
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Affiliation(s)
- Morten Skøtt Thomsen
- Neurobiology Research Unit, University Hospital Copenhagen, Rigshospitalet, Copenhagen, Denmark
| | - Ruud Zwart
- Lilly Research Centre, Eli Lilly and Company Limited, Erl Wood Manor, United Kingdom
| | - Daniel Ursu
- Lilly Research Centre, Eli Lilly and Company Limited, Erl Wood Manor, United Kingdom
| | - Majbrit Myrup Jensen
- Neurobiology Research Unit, University Hospital Copenhagen, Rigshospitalet, Copenhagen, Denmark
| | - Lars Hageman Pinborg
- Neurobiology Research Unit, University Hospital Copenhagen, Rigshospitalet, Copenhagen, Denmark
- Epilepsy Clinic, University Hospital Copenhagen, Rigshospitalet, Copenhagen, Denmark
| | - Gary Gilmour
- Lilly Research Centre, Eli Lilly and Company Limited, Erl Wood Manor, United Kingdom
| | - Jie Wu
- Divisions of Neurology, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, United States of America
| | - Emanuele Sher
- Lilly Research Centre, Eli Lilly and Company Limited, Erl Wood Manor, United Kingdom
| | - Jens Damsgaard Mikkelsen
- Neurobiology Research Unit, University Hospital Copenhagen, Rigshospitalet, Copenhagen, Denmark
- * E-mail:
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20
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Moretti M, Zoli M, George AA, Lukas RJ, Pistillo F, Maskos U, Whiteaker P, Gotti C. The novel α7β2-nicotinic acetylcholine receptor subtype is expressed in mouse and human basal forebrain: biochemical and pharmacological characterization. Mol Pharmacol 2014; 86:306-17. [PMID: 25002271 DOI: 10.1124/mol.114.093377] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We examined α7β2-nicotinic acetylcholine receptor (α7β2-nAChR) expression in mammalian brain and compared pharmacological profiles of homomeric α7-nAChRs and α7β2-nAChRs. α-Bungarotoxin affinity purification or immunoprecipitation with anti-α7 subunit antibodies (Abs) was used to isolate nAChRs containing α7 subunits from mouse or human brain samples. α7β2-nAChRs were detected in forebrain, but not other tested regions, from both species, based on Western blot analysis of isolates using β2 subunit-specific Abs. Ab specificity was confirmed in control studies using subunit-null mutant mice or cell lines heterologously expressing specific human nAChR subtypes and subunits. Functional expression in Xenopus oocytes of concatenated pentameric (α7)5-, (α7)4(β2)1-, and (α7)3(β2)2-nAChRs was confirmed using two-electrode voltage clamp recording of responses to nicotinic ligands. Importantly, pharmacological profiles were indistinguishable for concatenated (α7)5-nAChRs or for homomeric α7-nAChRs constituted from unlinked α7 subunits. Pharmacological profiles were similar for (α7)5-, (α7)4(β2)1-, and (α7)3(β2)2-nAChRs except for diminished efficacy of nicotine (normalized to acetylcholine efficacy) at α7β2- versus α7-nAChRs. This study represents the first direct confirmation of α7β2-nAChR expression in human and mouse forebrain, supporting previous mouse studies that suggested relevance of α7β2-nAChRs in Alzheimer disease etiopathogenesis. These data also indicate that α7β2-nAChR subunit isoforms with different α7/β2 subunit ratios have similar pharmacological profiles to each other and to α7 homopentameric nAChRs. This supports the hypothesis that α7β2-nAChR agonist activation predominantly or entirely reflects binding to α7/α7 subunit interface sites.
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Affiliation(s)
- Milena Moretti
- CNR Institute of Neuroscience, Biometra University of Milan, Milan, Italy (M.M., F.P., C.G.); Section of Physiology and Neurosciences, Department of Biomedical, Metabolic, and Neural Sciences, University of Modena and Reggio Emilia, Modena, Italy (M.Z.); Division of Neurobiology, Barrow Neurologic Institute, Phoenix, Arizona (A.A.G., R.J.L., P.W.); and Centre National de la Recherche Scientifique, Unité Neurobiologie Intégrative des Systèmes Cholinergiques, Institut Pasteur, Paris, France (U.M.)
| | - Michele Zoli
- CNR Institute of Neuroscience, Biometra University of Milan, Milan, Italy (M.M., F.P., C.G.); Section of Physiology and Neurosciences, Department of Biomedical, Metabolic, and Neural Sciences, University of Modena and Reggio Emilia, Modena, Italy (M.Z.); Division of Neurobiology, Barrow Neurologic Institute, Phoenix, Arizona (A.A.G., R.J.L., P.W.); and Centre National de la Recherche Scientifique, Unité Neurobiologie Intégrative des Systèmes Cholinergiques, Institut Pasteur, Paris, France (U.M.)
| | - Andrew A George
- CNR Institute of Neuroscience, Biometra University of Milan, Milan, Italy (M.M., F.P., C.G.); Section of Physiology and Neurosciences, Department of Biomedical, Metabolic, and Neural Sciences, University of Modena and Reggio Emilia, Modena, Italy (M.Z.); Division of Neurobiology, Barrow Neurologic Institute, Phoenix, Arizona (A.A.G., R.J.L., P.W.); and Centre National de la Recherche Scientifique, Unité Neurobiologie Intégrative des Systèmes Cholinergiques, Institut Pasteur, Paris, France (U.M.)
| | - Ronald J Lukas
- CNR Institute of Neuroscience, Biometra University of Milan, Milan, Italy (M.M., F.P., C.G.); Section of Physiology and Neurosciences, Department of Biomedical, Metabolic, and Neural Sciences, University of Modena and Reggio Emilia, Modena, Italy (M.Z.); Division of Neurobiology, Barrow Neurologic Institute, Phoenix, Arizona (A.A.G., R.J.L., P.W.); and Centre National de la Recherche Scientifique, Unité Neurobiologie Intégrative des Systèmes Cholinergiques, Institut Pasteur, Paris, France (U.M.)
| | - Francesco Pistillo
- CNR Institute of Neuroscience, Biometra University of Milan, Milan, Italy (M.M., F.P., C.G.); Section of Physiology and Neurosciences, Department of Biomedical, Metabolic, and Neural Sciences, University of Modena and Reggio Emilia, Modena, Italy (M.Z.); Division of Neurobiology, Barrow Neurologic Institute, Phoenix, Arizona (A.A.G., R.J.L., P.W.); and Centre National de la Recherche Scientifique, Unité Neurobiologie Intégrative des Systèmes Cholinergiques, Institut Pasteur, Paris, France (U.M.)
| | - Uwe Maskos
- CNR Institute of Neuroscience, Biometra University of Milan, Milan, Italy (M.M., F.P., C.G.); Section of Physiology and Neurosciences, Department of Biomedical, Metabolic, and Neural Sciences, University of Modena and Reggio Emilia, Modena, Italy (M.Z.); Division of Neurobiology, Barrow Neurologic Institute, Phoenix, Arizona (A.A.G., R.J.L., P.W.); and Centre National de la Recherche Scientifique, Unité Neurobiologie Intégrative des Systèmes Cholinergiques, Institut Pasteur, Paris, France (U.M.)
| | - Paul Whiteaker
- CNR Institute of Neuroscience, Biometra University of Milan, Milan, Italy (M.M., F.P., C.G.); Section of Physiology and Neurosciences, Department of Biomedical, Metabolic, and Neural Sciences, University of Modena and Reggio Emilia, Modena, Italy (M.Z.); Division of Neurobiology, Barrow Neurologic Institute, Phoenix, Arizona (A.A.G., R.J.L., P.W.); and Centre National de la Recherche Scientifique, Unité Neurobiologie Intégrative des Systèmes Cholinergiques, Institut Pasteur, Paris, France (U.M.)
| | - Cecilia Gotti
- CNR Institute of Neuroscience, Biometra University of Milan, Milan, Italy (M.M., F.P., C.G.); Section of Physiology and Neurosciences, Department of Biomedical, Metabolic, and Neural Sciences, University of Modena and Reggio Emilia, Modena, Italy (M.Z.); Division of Neurobiology, Barrow Neurologic Institute, Phoenix, Arizona (A.A.G., R.J.L., P.W.); and Centre National de la Recherche Scientifique, Unité Neurobiologie Intégrative des Systèmes Cholinergiques, Institut Pasteur, Paris, France (U.M.)
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21
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Yakel JL. Nicotinic ACh receptors in the hippocampal circuit; functional expression and role in synaptic plasticity. J Physiol 2014; 592:4147-53. [PMID: 24860170 DOI: 10.1113/jphysiol.2014.273896] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Acetylcholine (ACh) can regulate neuronal excitability in the hippocampus, an important area in the brain for learning and memory, by acting on both nicotinic (nAChRs) and muscarinic ACh receptors. The primary cholinergic input to the hippocampus arises from the medial septum and diagonal band of Broca (MS-DBB), and we investigated how their activation regulated hippocampal synaptic plasticity. We found that activation of these endogenous cholinergic inputs can directly induce different forms of hippocampal synaptic plasticity with a timing precision in the millisecond range. Furthermore, we observed a prolonged enhancement of excitability both pre- and postsynaptically. Lastly we found that the presence of the α7 nAChR subtype to both pre- and postsynaptic sites appeared to be required to induce this plasticity. We propose that α7 nAChRs coordinate pre- and postsynaptic activities to induce glutamatergic synaptic plasticity, and thus provide a novel mechanism underlying physiological neuronal communication that could lead to timing-dependent synaptic plasticity in the hippocampus.
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Affiliation(s)
- Jerrel L Yakel
- Laboratory of Neurobiology, National Institute of Environmental Health Sciences, National Institutes of Health, Department of Health and Human Services, Research Triangle Park, NC 27709, USA
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22
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Brown JL, Wonnacott S. Sazetidine-A Activates and Desensitizes Native α7 Nicotinic Acetylcholine Receptors. Neurochem Res 2014; 40:2047-54. [PMID: 24728867 PMCID: PMC4630245 DOI: 10.1007/s11064-014-1302-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2014] [Revised: 03/24/2014] [Accepted: 04/01/2014] [Indexed: 12/24/2022]
Abstract
The aim of this study was to investigate the ability of sazetidine-A, a novel partial agonist at α4β2 nicotinic acetylcholine receptors (nAChRs), to affect the function of native α7 nAChRs in SH-SY5Y cells and primary cortical cultures. The α7-selective positive allosteric modulator PNU-120596 was used to reveal receptor activation, measured as an increase in intracellular calcium using fluorescent indicators. In the absence of PNU-120596, sazetidine-A elicited mecamylamine-sensitive increases in fluorescence in SH-SY5Y cells (EC50 4.2 µM) but no responses from primary cortical neurons. In the presence on PNU-120596, an additional response to sazetidine-A was observed in SH-SY5Y cells (EC50 0.4 µM) and robust responses were recorded in 14 % of cortical neurons. These PNU-120596-dependent responses were blocked by methyllycaconitine, consistent with the activation of α7 nAChRs. Preincubtion with sazetidine-A concentration-dependently attenuated subsequent responses to the α7-selective agonist PNU-282987 in SH-SY5Y cells (IC50 476 nM) and cortical cultures. These findings support the ability of sazetidine-A to interact with α7 nAChRs, which may contribute to sazetidine-A’s actions in complex physiological systems.
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Affiliation(s)
- Jack L Brown
- Department of Biology and Biochemistry, University of Bath, Bath, BA2 7AY, UK
| | - Susan Wonnacott
- Department of Biology and Biochemistry, University of Bath, Bath, BA2 7AY, UK.
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