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Neonicotinoid Insecticides Alter the Gene Expression Profile of Neuron-Enriched Cultures from Neonatal Rat Cerebellum. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2016; 13:ijerph13100987. [PMID: 27782041 PMCID: PMC5086726 DOI: 10.3390/ijerph13100987] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/20/2016] [Accepted: 09/27/2016] [Indexed: 01/02/2023]
Abstract
Neonicotinoids are considered safe because of their low affinities to mammalian nicotinic acetylcholine receptors (nAChRs) relative to insect nAChRs. However, because of importance of nAChRs in mammalian brain development, there remains a need to establish the safety of chronic neonicotinoid exposures with regards to children's health. Here we examined the effects of longterm (14 days) and low dose (1 μM) exposure of neuron-enriched cultures from neonatal rat cerebellum to nicotine and two neonicotinoids: acetamiprid and imidacloprid. Immunocytochemistry revealed no differences in the number or morphology of immature neurons or glial cells in any group versus untreated control cultures. However, a slight disturbance in Purkinje cell dendritic arborization was observed in the exposed cultures. Next we performed transcriptome analysis on total RNAs using microarrays, and identified significant differential expression (p < 0.05, q < 0.05, ≥1.5 fold) between control cultures versus nicotine-, acetamiprid-, or imidacloprid-exposed cultures in 34, 48, and 67 genes, respectively. Common to all exposed groups were nine genes essential for neurodevelopment, suggesting that chronic neonicotinoid exposure alters the transcriptome of the developing mammalian brain in a similar way to nicotine exposure. Our results highlight the need for further careful investigations into the effects of neonicotinoids in the developing mammalian brain.
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Fox-Loe AM, Dwoskin LP, Richards CI. Nicotinic Acetylcholine Receptors as Targets for Tobacco Cessation Therapeutics: Cutting-Edge Methodologies to Understand Receptor Assembly and Trafficking. NEUROMETHODS 2016; 117:119-132. [PMID: 28025590 DOI: 10.1007/978-1-4939-3768-4_7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Tobacco dependence is a chronic relapsing disorder and nicotine, the primary alkaloid in tobacco, acts at nicotinic receptors to stimulate dopamine release in brain, which is responsible for the reinforcing properties of nicotine, leading to addiction. Although the majority of tobacco users express the desire to quit, only a small percentage of those attempting to quit are successful using the currently available pharmacotherapies. Nicotine upregulates the number of specific nicotinic receptors on the neuronal cell surface. An increase in receptor trafficking or preferential stoichiometric assembly of receptor subunits involves changes in assembly, endoplasmic reticulum export, vesicle transport, decreased degradation, desensitization, enhanced maturation of functional pentamers, and pharmacological chaperoning. Understanding these changes on a mechanistic level is important to the development of nicotinic receptors as drug targets. For this reason, cutting-edge methodologies are being developed and employed to pinpoint distinct changes in localization, assembly, export, vesicle trafficking, and stoichiometry in order to further understand the physiology of these receptors and to evaluate the action of novel therapeutics for smoking cessation.
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Striosome-dendron bouquets highlight a unique striatonigral circuit targeting dopamine-containing neurons. Proc Natl Acad Sci U S A 2016; 113:11318-11323. [PMID: 27647894 DOI: 10.1073/pnas.1613337113] [Citation(s) in RCA: 90] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
The dopamine systems of the brain powerfully influence movement and motivation. We demonstrate that striatonigral fibers originating in striosomes form highly unusual bouquet-like arborizations that target bundles of ventrally extending dopamine-containing dendrites and clusters of their parent nigral cell bodies. Retrograde tracing showed that these clustered cell bodies in turn project to the striatum as part of the classic nigrostriatal pathway. Thus, these striosome-dendron formations, here termed "striosome-dendron bouquets," likely represent subsystems with the nigro-striato-nigral loop that are affected in human disorders including Parkinson's disease. Within the bouquets, expansion microscopy resolved many individual striosomal fibers tightly intertwined with the dopamine-containing dendrites and also with afferents labeled by glutamatergic, GABAergic, and cholinergic markers and markers for astrocytic cells and fibers and connexin 43 puncta. We suggest that the striosome-dendron bouquets form specialized integrative units within the dopamine-containing nigral system. Given evidence that striosomes receive input from cortical regions related to the control of mood and motivation and that they link functionally to reinforcement and decision-making, the striosome-dendron bouquets could be critical to dopamine-related function in health and disease.
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Arvaniti M, Jensen MM, Soni N, Wang H, Klein AB, Thiriet N, Pinborg LH, Muldoon PP, Wienecke J, Imad Damaj M, Kohlmeier KA, Gondré-Lewis MC, Mikkelsen JD, Thomsen MS. Functional interaction between Lypd6 and nicotinic acetylcholine receptors. J Neurochem 2016; 138:806-20. [PMID: 27344019 PMCID: PMC5017906 DOI: 10.1111/jnc.13718] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2016] [Revised: 06/22/2016] [Accepted: 06/24/2016] [Indexed: 01/15/2023]
Abstract
Nicotinic acetylcholine receptors (nAChRs) affect multiple physiological functions in the brain and their functions are modulated by regulatory proteins of the Lynx family. Here, we report for the first time a direct interaction of the Lynx protein LY6/PLAUR domain-containing 6 (Lypd6) with nAChRs in human brain extracts, identifying Lypd6 as a novel regulator of nAChR function. Using protein cross-linking and affinity purification from human temporal cortical extracts, we demonstrate that Lypd6 is a synaptically enriched membrane-bound protein that binds to multiple nAChR subtypes in the human brain. Additionally, soluble recombinant Lypd6 protein attenuates nicotine-induced hippocampal inward currents in rat brain slices and decreases nicotine-induced extracellular signal-regulated kinase phosphorylation in PC12 cells, suggesting that binding of Lypd6 is sufficient to inhibit nAChR-mediated intracellular signaling. We further show that perinatal nicotine exposure in rats (4 mg/kg/day through minipumps to dams from embryonic day 7 to post-natal day 21) significantly increases Lypd6 protein levels in the hippocampus in adulthood, which did not occur after exposure to nicotine in adulthood only. Our findings suggest that Lypd6 is a versatile inhibitor of cholinergic signaling in the brain, and that Lypd6 is dysregulated by nicotine exposure during early development. Regulatory proteins of the Lynx family modulate the function of nicotinic receptors (nAChRs). We report for the first time that the Lynx protein Lypd6 binds to nAChRs in human brain extracts, and that recombinant Lypd6 decreases nicotine-induced ERK phosphorylation and attenuates nicotine-induced hippocampal inward currents. Our findings suggest that Lypd6 is a versatile inhibitor of cholinergic signaling in the brain.
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Affiliation(s)
- Maria Arvaniti
- Department of Drug Design & Pharmacology, University of Copenhagen, Copenhagen, Denmark
| | - Majbrit M Jensen
- Neurobiology Research Unit, University Hospital Copenhagen, Rigshospitalet, Copenhagen, Denmark
| | - Neeraj Soni
- Department of Drug Design & Pharmacology, University of Copenhagen, Copenhagen, Denmark
| | - Hong Wang
- Laboratory for Neurodevelopment, Department of Anatomy, Howard University College of Medicine, Washington, District of Columbia, USA
| | - Anders B Klein
- Department of Drug Design & Pharmacology, University of Copenhagen, Copenhagen, Denmark
| | - Nathalie Thiriet
- Laboratory of Experimental and Clinical Neurosciences, University of Poitiers, Poitiers, France
| | - Lars H Pinborg
- Neurobiology Research Unit, University Hospital Copenhagen, Rigshospitalet, Copenhagen, Denmark.,Epilepsy Clinic, University Hospital Copenhagen, Rigshospitalet, Copenhagen, Denmark
| | - Pretal P Muldoon
- Department of Pharmacology and Toxicology, Medical College of Virginia, Virginia Commonwealth University, Richmond, Virginia, USA
| | - Jacob Wienecke
- Department of Nutrition, Exercise and Sport & Department of Neuroscience and Pharmacology, University of Copenhagen, Copenhagen, Denmark
| | - M Imad Damaj
- Department of Pharmacology and Toxicology, Medical College of Virginia, Virginia Commonwealth University, Richmond, Virginia, USA
| | - Kristi A Kohlmeier
- Department of Drug Design & Pharmacology, University of Copenhagen, Copenhagen, Denmark
| | - Marjorie C Gondré-Lewis
- Laboratory for Neurodevelopment, Department of Anatomy, Howard University College of Medicine, Washington, District of Columbia, USA
| | - Jens D Mikkelsen
- Neurobiology Research Unit, University Hospital Copenhagen, Rigshospitalet, Copenhagen, Denmark
| | - Morten S Thomsen
- Department of Drug Design & Pharmacology, University of Copenhagen, Copenhagen, Denmark. .,Neurobiology Research Unit, University Hospital Copenhagen, Rigshospitalet, Copenhagen, Denmark.
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55
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Faure G, Shelukhina IV, Porowinska D, Shulepko MA, Lyukmanova EN, Dolgikh DA, Spirova EN, Kasheverov IE, Utkin YN, Corringer JP, Tsetlin VI. Interaction of three-finger proteins from snake venoms and from mammalian brain with the cys-loop receptors and their models. DOKL BIOCHEM BIOPHYS 2016; 468:193-6. [DOI: 10.1134/s1607672916030091] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2015] [Indexed: 11/23/2022]
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56
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Gass N, Weber-Fahr W, Sartorius A, Becker R, Didriksen M, Stensbøl TB, Bastlund JF, Meyer-Lindenberg A, Schwarz AJ. An acetylcholine alpha7 positive allosteric modulator rescues a schizophrenia-associated brain endophenotype in the 15q13.3 microdeletion, encompassing CHRNA7. Eur Neuropsychopharmacol 2016; 26:1150-60. [PMID: 27061851 DOI: 10.1016/j.euroneuro.2016.03.013] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/24/2016] [Revised: 03/20/2016] [Accepted: 03/21/2016] [Indexed: 01/01/2023]
Abstract
The 15q13.3 microdeletion copy number variation is strongly associated with schizophrenia and epilepsy. The CHRNA7 gene, encoding nicotinic acetylcholine alpha 7 receptors (nAChA7Rs), is hypothesized to be one of the main genes in this deletion causing the neuropsychiatric phenotype. Here we used a recently developed 15q13.3 microdeletion mouse model to explore whether an established schizophrenia-associated connectivity phenotype is replicated in a murine model, and whether positive modulation of nAChA7 receptor might pharmacologically normalize the connectivity patterns. Resting-state fMRI data were acquired from male mice carrying a hemizygous 15q13.3 microdeletion (N=9) and from wild-type mice (N=9). To study the connectivity profile of 15q13.3 mice and test the effect of nAChA7 positive allosteric modulation, the 15q13.3 mice underwent two imaging sessions, one week apart, receiving a single intraperitoneal injection of either 15mg/kg Lu AF58801 or saline. The control group comprised wild-type mice treated with saline. We performed seed-based functional connectivity analysis to delineate aberrant connectivity patterns associated with the deletion (15q13.3 mice (saline treatment) versus wild-type mice (saline treatment)) and their modulation by Lu AF58801 (15q13.3 mice (Lu AF58801 treatment) versus 15q13.3 mice (saline treatment)). Compared to wild-type mice, 15q13.3 mice evidenced a predominant hyperconnectivity pattern. The main effect of Lu AF58801 was a normalization of elevated functional connectivity between prefrontal and frontal, hippocampal, striatal, thalamic and auditory regions. The strongest effects were observed in brain regions expressing nAChA7Rs, namely hippocampus, cerebral cortex and thalamus. These effects may underlie the antiepileptic, pro-cognitive and auditory gating deficit-reversal effects of nAChA7R stimulation.
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Affiliation(s)
- Natalia Gass
- Research Group Translational Imaging, Department of Neuroimaging, Central Institute of Mental Health, Medical Faculty Mannheim, University of Heidelberg, Germany.
| | - Wolfgang Weber-Fahr
- Research Group Translational Imaging, Department of Neuroimaging, Central Institute of Mental Health, Medical Faculty Mannheim, University of Heidelberg, Germany
| | - Alexander Sartorius
- Research Group Translational Imaging, Department of Neuroimaging, Central Institute of Mental Health, Medical Faculty Mannheim, University of Heidelberg, Germany; Department of Psychiatry and Psychotherapy, Central Institute of Mental Health, Medical Faculty Mannheim, University of Heidelberg, Germany
| | - Robert Becker
- Research Group Translational Imaging, Department of Neuroimaging, Central Institute of Mental Health, Medical Faculty Mannheim, University of Heidelberg, Germany
| | | | | | | | - Andreas Meyer-Lindenberg
- Department of Psychiatry and Psychotherapy, Central Institute of Mental Health, Medical Faculty Mannheim, University of Heidelberg, Germany
| | - Adam J Schwarz
- Tailored Therapeutics - Neuroscience, Eli Lilly and Company, Indianapolis, IN, USA; Department of Psychological and Brain Sciences, Indiana University, Bloomington, IN, USA; Department of Radiology and Imaging Sciences, Indiana University, Indianapolis, IN, USA
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Thomsen MS, Arvaniti M, Jensen MM, Shulepko MA, Dolgikh DA, Pinborg LH, Härtig W, Lyukmanova EN, Mikkelsen JD. Lynx1 and Aβ1-42 bind competitively to multiple nicotinic acetylcholine receptor subtypes. Neurobiol Aging 2016; 46:13-21. [PMID: 27460145 DOI: 10.1016/j.neurobiolaging.2016.06.009] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2015] [Revised: 06/09/2016] [Accepted: 06/10/2016] [Indexed: 01/13/2023]
Abstract
Lynx1 regulates synaptic plasticity in the brain by regulating nicotinic acetylcholine receptors (nAChRs). It is not known to which extent Lynx1 can bind to endogenous nAChR subunits in the brain or how this interaction is affected by Alzheimer's disease pathology. We apply affinity purification to demonstrate that a water-soluble variant of human Lynx1 (Ws-Lynx1) isolates α3, α4, α5, α6, α7, β2, and β4 nAChR subunits from human and rat cortical extracts, and rat midbrain and olfactory bulb extracts, suggesting that Lynx1 forms complexes with multiple nAChR subtypes in the human and rodent brain. Incubation with Ws-Lynx1 decreases nicotine-mediated extracellular signal-regulated kinase phosphorylation in PC12 cells and striatal neurons, indicating that binding of Ws-Lynx1 is sufficient to inhibit signaling downstream of nAChRs. The effect of nicotine in PC12 cells is independent of α7 or α4β2 nAChRs, suggesting that Lynx1 can affect the function of native non-α7, non-α4β2 nAChR subtypes. We further show that Lynx1 and oligomeric β-amyloid1-42 compete for binding to several nAChR subunits, that Ws-Lynx1 prevents β-amyloid1-42-induced cytotoxicity in cortical neurons, and that cortical Lynx1 levels are decreased in a transgenic mouse model with concomitant β-amyloid and tau pathology. Our data suggest that Lynx1 binds to multiple nAChR subtypes in the brain and that this interaction might have functional and pathophysiological implications in relation to Alzheimer's disease.
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Affiliation(s)
- Morten S Thomsen
- Neurobiology Research Unit, University Hospital Copenhagen, Rigshospitalet, Copenhagen, Denmark; Department of Drug Design & Pharmacology, University of Copenhagen, Copenhagen, Denmark.
| | - Maria Arvaniti
- Department of Drug Design & Pharmacology, University of Copenhagen, Copenhagen, Denmark
| | - Majbrit M Jensen
- Neurobiology Research Unit, University Hospital Copenhagen, Rigshospitalet, Copenhagen, Denmark
| | - Mikhail A Shulepko
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, Russia; Lomonosov Moscow State University, Moscow, Russia
| | - Dmitry A Dolgikh
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, Russia; Lomonosov Moscow State University, Moscow, Russia
| | - Lars H Pinborg
- Neurobiology Research Unit, University Hospital Copenhagen, Rigshospitalet, Copenhagen, Denmark; Epilepsy Clinic, University Hospital Copenhagen, Rigshospitalet, Copenhagen, Denmark
| | - Wolfgang Härtig
- Paul Flechsig Institute for Brain Research, University of Leipzig, Leipzig, Germany
| | - Ekaterina N Lyukmanova
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, Russia; Lomonosov Moscow State University, Moscow, Russia
| | - Jens D Mikkelsen
- Neurobiology Research Unit, University Hospital Copenhagen, Rigshospitalet, Copenhagen, Denmark
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Wang J, Wang Y, Guo F, Feng Z, Wang X, Lu C. Nicotinic modulation of Ca2+ oscillations in rat cortical neurons in vitro. Am J Physiol Cell Physiol 2016; 310:C748-54. [DOI: 10.1152/ajpcell.00197.2015] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2015] [Accepted: 01/29/2016] [Indexed: 01/28/2023]
Abstract
The roles of nicotine on Ca2+ oscillations [intracellular Ca2+ ([Ca2+]i) oscillation] in rat primary cultured cortical neurons were studied. The spontaneous [Ca2+]i oscillations (SCO) were recorded in a portion of the neurons (65%) cultured for 7–10 days in vitro. Application of nicotine enhanced [Ca2+]i oscillation frequency and amplitude, which were reduced by the selective α4β2-nicotinic acetylcholine receptors (nAChRs) antagonist dihydro-β-erythroidine (DHβE) hydrobromide, and the selective α7-nAChRs antagonist methyllycaconitine citrate (MLA, 20 nM). DHβE reduced SCO frequency and prevented the nicotinic increase in the frequency. DHβE somewhat enhanced SCO amplitude and prevented nicotinic increase in the amplitude. MLA (20 nM) itself reduced SCO frequency without affecting the amplitude but blocked nicotinic increase in [Ca2+]i oscillation frequency and amplitude. Furthermore, coadministration of both α4β2- and α7-nAChRs antagonists completely prevented nicotinic increment in [Ca2+]i oscillation frequency and amplitude. Thus, our results indicate that both α4β2- and α7-nAChRs mediated nicotine-induced [Ca2+]i oscillations, and two nAChR subtypes differentially regulated SCO.
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Affiliation(s)
- JianGang Wang
- Henan Province Key Laboratory of Brain Research, Xinxiang Medical University, Xinxiang, Henan, Peoples Republic of China
- Department of Pathophysiology, Xinxiang Medical University, Xinxiang, Henan, Peoples Republic of China
| | - YaLi Wang
- Henan Province Key Laboratory of Brain Research, Xinxiang Medical University, Xinxiang, Henan, Peoples Republic of China
- Department of Physiology and Neurobiology, Xinxiang Medical University, Xinxiang, Henan, Peoples Republic of China; and
| | - FangLi Guo
- Henan Province Key Laboratory of Brain Research, Xinxiang Medical University, Xinxiang, Henan, Peoples Republic of China
- Department of Physiology and Neurobiology, Xinxiang Medical University, Xinxiang, Henan, Peoples Republic of China; and
| | - ZhiBo Feng
- Department of Anatomy, Xinxiang Medical University, Xinxiang, Henan, Peoples Republic of China
| | - XiangFang Wang
- Henan Province Key Laboratory of Brain Research, Xinxiang Medical University, Xinxiang, Henan, Peoples Republic of China
| | - ChengBiao Lu
- Henan Province Key Laboratory of Brain Research, Xinxiang Medical University, Xinxiang, Henan, Peoples Republic of China
- Department of Physiology and Neurobiology, Xinxiang Medical University, Xinxiang, Henan, Peoples Republic of China; and
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59
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Cholinergic modulation of auditory steady-state response in the auditory cortex of the freely moving rat. Neuroscience 2016; 324:29-39. [PMID: 26964684 DOI: 10.1016/j.neuroscience.2016.03.006] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2016] [Revised: 02/16/2016] [Accepted: 03/03/2016] [Indexed: 12/22/2022]
Abstract
As disturbance in auditory steady-state response (ASSR) has been consistently found in many neuropsychiatric disorders, such as autism spectrum disorder and schizophrenia, there is considerable interest in the development of translational rat models to elucidate the underlying neural and neurochemical mechanisms involved in ASSR. This is the first study to investigate the effects of the non-selective muscarinic antagonist scopolamine and the cholinesterase inhibitor donepezil (also in combination with scopolamine) on ASSR. We recorded the local field potentials through the chronic microelectrodes implanted in the auditory cortex of freely moving rat. ASSRs were recorded in response to auditory stimuli delivered over a range of frequencies (10-80 Hz) and averaged over 60 trials. We found that a single dose of scopolamine produced a temporal attenuation in response to auditory stimuli; the most attenuation occurred at 40 Hz. Time-frequency analysis revealed deficits in both power and phase-locking to 40 Hz. Donepezil augmented 40-Hz steady-state power and phase-locking. Scopolamine combined with donepezil had an enhanced effect on the phase-locking, but not power of ASSR. These changes induced by cholinergic drugs suggest an involvement of muscarinic neurotransmission in auditory processing and provide a rodent model investigating the neurochemical mechanism of neurophysiological deficits seen in patients.
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60
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Ochoa V, George AA, Nishi R, Whiteaker P. The prototoxin LYPD6B modulates heteromeric α3β4-containing nicotinic acetylcholine receptors, but not α7 homomers. FASEB J 2016; 30:1109-19. [PMID: 26586467 PMCID: PMC4750422 DOI: 10.1096/fj.15-274548] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2015] [Accepted: 11/09/2015] [Indexed: 12/16/2022]
Abstract
Prototoxins are a diverse family of membrane-tethered molecules expressed in the nervous system that modulate nicotinic cholinergic signaling, but their functions and specificity have yet to be completely explored. We tested the selectivity and efficacy of leukocyte antigen, PLAUR (plasminogen activator, urokinase receptor) domain-containing (LYPD)-6B on α3β4-, α3α5β4-, and α7-containing nicotinic acetylcholine receptors (nAChRs). To constrain stoichiometry, fusion proteins encoding concatemers of human α3, β4, and α5 (D and N variants) subunits were expressed in Xenopus laevis oocytes and tested with or without LYPD6B. We used the 2-electrode voltage-clamp method to quantify responses to acetylcholine (ACh): agonist sensitivity (EC50), maximal agonist-induced current (Imax), and time constant (τ) of desensitization. For β4-α3-α3-β4-α3 and β4-α3-β4-α3-α3, LYPD6B decreased EC50 from 631 to 79 μM, reduced Imax by at least 59%, and decreased τ. For β4-α3-α5D-β4-α3 and β4-α3-β4-α-α5D, LYPD6B decreased Imax by 63 and 32%, respectively. Thus, LYPD6B acted only on (α3)3(β4)2 and (α3)2(α5D)(β4)2 and did not affect the properties of (α3)2(β4)3, α7, or (α3)2(α5N)(β4)2 nAChRs. Therefore, LYPD6B acts as a mixed modulator that enhances the sensitivity of (α3)3(β4)2 nAChRs to ACh while reducing ACh-induced whole-cell currents. LYPD6B also negatively modulates α3β4 nAChRs that include the α5D common human variant, but not the N variant associated with nicotine dependence.
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Affiliation(s)
- Vanessa Ochoa
- *Neuroscience Graduate Program, Department of Neurological Sciences, University of Vermont, Burlington, Vermont, USA; and Division of Neurobiology, Barrow Neurological Institute, Phoenix, Arizona, USA
| | - Andrew A George
- *Neuroscience Graduate Program, Department of Neurological Sciences, University of Vermont, Burlington, Vermont, USA; and Division of Neurobiology, Barrow Neurological Institute, Phoenix, Arizona, USA
| | - Rae Nishi
- *Neuroscience Graduate Program, Department of Neurological Sciences, University of Vermont, Burlington, Vermont, USA; and Division of Neurobiology, Barrow Neurological Institute, Phoenix, Arizona, USA
| | - Paul Whiteaker
- *Neuroscience Graduate Program, Department of Neurological Sciences, University of Vermont, Burlington, Vermont, USA; and Division of Neurobiology, Barrow Neurological Institute, Phoenix, Arizona, USA
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Srinivasan R, Henley BM, Henderson BJ, Indersmitten T, Cohen BN, Kim CH, McKinney S, Deshpande P, Xiao C, Lester HA. Smoking-Relevant Nicotine Concentration Attenuates the Unfolded Protein Response in Dopaminergic Neurons. J Neurosci 2016; 36:65-79. [PMID: 26740650 PMCID: PMC4701966 DOI: 10.1523/jneurosci.2126-15.2016] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2015] [Revised: 11/09/2015] [Accepted: 11/13/2015] [Indexed: 01/01/2023] Open
Abstract
Retrospective epidemiological studies show an inverse correlation between susceptibility to Parkinson's disease and a person's history of tobacco use. Animal model studies suggest nicotine as a neuroprotective agent and nicotinic acetylcholine (ACh) receptors (nAChRs) as targets for neuroprotection, but the underlying neuroprotective mechanism(s) are unknown. We cultured mouse ventral midbrain neurons for 3 weeks. Ten to 20% of neurons were dopaminergic (DA), revealed by tyrosine hydroxylase (TH) immunoreactivity. We evoked mild endoplasmic reticulum (ER) stress with tunicamycin (Tu), producing modest increases in the level of nuclear ATF6, phosphorylated eukaryotic initiation factor 2α, nuclear XBP1, and the downstream proapoptotic effector nuclear C/EBP homologous protein. We incubated cultures for 2 weeks with 200 nm nicotine, the approximate steady-state concentration between cigarette smoking or vaping, or during nicotine patch use. Nicotine incubation suppressed Tu-induced ER stress and the unfolded protein response (UPR). Study of mice with fluorescent nAChR subunits showed that the cultured TH+ neurons displayed α4, α6, and β3 nAChR subunit expression and ACh-evoked currents. Gene expression profile in cultures from TH-eGFP mice showed that the TH+ neurons also express several other genes associated with DA release. Nicotine also upregulated ACh-induced currents in DA neurons by ∼2.5-fold. Thus, nicotine, at a concentration too low to activate an appreciable fraction of plasma membrane nAChRs, induces two sequelae of pharmacological chaperoning in the ER: UPR suppression and nAChR upregulation. Therefore, one mechanism of neuroprotection by nicotine is pharmacological chaperoning, leading to UPR suppression. Measuring this pathway may help in assessing neuroprotection. SIGNIFICANCE STATEMENT Parkinson's disease (PD) cannot yet be cured or prevented. However, many retrospective epidemiological studies reveal that PD is diagnosed less frequently in tobacco users. Existing programs attempting to develop nicotinic drugs that might exert this apparent neuroprotective effect are asking whether agonists, antagonists, partial agonists, or channel blockers show the most promise. The underlying logic resembles the previous development of varenicline for smoking cessation. We studied whether, and how, nicotine produces neuroprotective effects in cultured dopaminergic neurons, an experimentally tractable, mechanistically revealing neuronal system. We show that nicotine, operating via nicotinic receptors, does protect these neurons against endoplasmic reticulum stress. However, the mechanism is probably "inside-out": pharmacological chaperoning in the endoplasmic reticulum. This cellular-level insight could help to guide neuroprotective strategies.
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Affiliation(s)
- Rahul Srinivasan
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91125
| | - Beverley M Henley
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91125
| | - Brandon J Henderson
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91125
| | - Tim Indersmitten
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91125
| | - Bruce N Cohen
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91125
| | - Charlene H Kim
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91125
| | - Sheri McKinney
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91125
| | - Purnima Deshpande
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91125
| | - Cheng Xiao
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91125
| | - Henry A Lester
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91125
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Abstract
UNLABELLED Experience-dependent cortical plasticity declines with age. At the molecular level, experience-dependent proteolytic activity of tissue plasminogen activator (tPA) becomes restricted in the adult brain if mice are raised in standard cages. Understanding the mechanism for the loss of permissive proteolytic activity is therefore a key link for improving function in adult brains. Using the mouse primary visual cortex (V1) as a model, we demonstrate that tPA activity in V1 can be unmasked following 4 d of monocular deprivation when the mice older than 2 months are raised in standard cages by the genetic removal of Lynx1, a negative regulator of adult plasticity. This was also associated with the reduction of stubby and thin spine density and enhancement of ocular dominance shift in adult V1 of Lynx1 knock-out (KO) mice. These structural and functional changes were tPA-dependent because genetic removal of tPA in Lynx1 KO mice can block the monocular deprivation-dependent reduction of dendritic spine density, whereas both genetic and adult specific inhibition of tPA activity can ablate the ocular dominance shift in Lynx1 KO mice. Our work demonstrates that the adult brain has an intrinsic potential for experience-dependent elevation of proteolytic activity to express juvenile-like structural and functional changes but is effectively limited by Lynx1 if mice are raised in standard cages. Insights into the Lynx1-tPA plasticity mechanism may provide novel therapeutic targets for adult brain disorders. SIGNIFICANCE STATEMENT Experience-dependent proteolytic activity of tissue plasminogen activator (tPA) becomes restricted in the adult brain in correlation with the decline in cortical plasticity when mice are raised in standard cages. We demonstrated that removal of Lynx1, one of negative regulators of plasticity, unmasks experience-dependent tPA elevation in visual cortex of adult mice reared in standard cages. This proteolytic elevation facilitated dendritic spine reduction and ocular dominance plasticity in adult visual cortex. This is the first demonstration of adult brain to retain the intrinsic capacity to elevate tPA in an experience-dependent manner but is effectively limited by Lynx1. tPA-Lynx1 may potentially be a new candidate mechanism for interventions that were shown to activate plasticity in adult brain.
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63
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Faillace MP, Bernabeu RO. Conditioned Place Preference and Behavioral Analysis to Evaluate Nicotine Reinforcement Properties in Zebrafish. NICOTINIC ACETYLCHOLINE RECEPTOR TECHNOLOGIES 2016. [DOI: 10.1007/978-1-4939-3768-4_3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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64
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Tregellas JR, Smucny J, Legget KT, Stevens KE. Effects of a ketogenic diet on auditory gating in DBA/2 mice: A proof-of-concept study. Schizophr Res 2015; 169:351-354. [PMID: 26453015 PMCID: PMC4827327 DOI: 10.1016/j.schres.2015.09.022] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/18/2015] [Revised: 09/18/2015] [Accepted: 09/21/2015] [Indexed: 11/20/2022]
Abstract
Although the ketogenic diet has shown promise in a pilot study and case report in schizophrenia, its effects in animal models of hypothesized disease mechanisms are unknown. This study examined effects of treatment with the ketogenic diet on hippocampal P20/N40 gating in DBA/2 mice, a translational endophenotype that mirrors inhibitory deficits in P50 sensory gating in schizophrenia patients. As expected, the diet increased blood ketone levels. Animals with the highest ketone levels showed the lowest P20/N40 gating ratios. These preliminary results suggest that the ketogenic diet may effectively target sensory gating deficits and is a promising area for additional research in schizophrenia.
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Affiliation(s)
- Jason R Tregellas
- Research Service, Denver VA Medical Center, Denver, CO, USA; Neuroscience Program, University of Colorado Anschutz Medical Campus, Aurora, CO, USA; Department of Psychiatry, University of Colorado Anschutz Medical Campus, Aurora, CO, USA.
| | - Jason Smucny
- Neuroscience Program, University of Colorado Anschutz Medical Campus, Aurora, CO, USA; Department of Psychiatry, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - Kristina T Legget
- Neuroscience Program, University of Colorado Anschutz Medical Campus, Aurora, CO, USA; Department of Psychiatry, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - Karen E Stevens
- Department of Psychiatry, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
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65
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Smucny J, Olincy A, Rojas DC, Tregellas JR. Neuronal effects of nicotine during auditory selective attention in schizophrenia. Hum Brain Mapp 2015; 37:410-21. [PMID: 26518728 DOI: 10.1002/hbm.23040] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2015] [Revised: 09/29/2015] [Accepted: 10/18/2015] [Indexed: 12/11/2022] Open
Abstract
Although nicotine has been shown to improve attention deficits in schizophrenia, the neurobiological mechanisms underlying this effect are poorly understood. We hypothesized that nicotine would modulate attention-associated neuronal response in schizophrenia patients in the ventral parietal cortex (VPC), hippocampus, and anterior cingulate based on previous findings in control subjects. To test this hypothesis, the present study examined response in these regions in a cohort of nonsmoking patients and healthy control subjects using an auditory selective attention task with environmental noise distractors during placebo and nicotine administration. In agreement with our hypothesis, significant diagnosis (Control vs. Patient) X drug (Placebo vs. Nicotine) interactions were observed in the VPC and hippocampus. The interaction was driven by task-associated hyperactivity in patients (relative to healthy controls) during placebo administration, and decreased hyperactivity in patients after nicotine administration (relative to placebo). No significant interaction was observed in the anterior cingulate. Task-associated hyperactivity of the VPC predicted poor task performance in patients during placebo. Poor task performance also predicted symptoms in patients as measured by the Brief Psychiatric Rating Scale. These results are the first to suggest that nicotine may modulate brain activity in a selective attention-dependent manner in schizophrenia.
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Affiliation(s)
- Jason Smucny
- Neuroscience Program, University of Colorado Anschutz Medical Campus, Aurora, Colorado.,Department of Psychiatry, University of Colorado Anschutz Medical Campus, Aurora, Colorado
| | - Ann Olincy
- Department of Psychiatry, University of Colorado Anschutz Medical Campus, Aurora, Colorado.,Research Service, Denver VA Medical Center, Denver, Colorado
| | - Donald C Rojas
- Department of Psychology, Colorado State University, Fort Collins, Colorado
| | - Jason R Tregellas
- Neuroscience Program, University of Colorado Anschutz Medical Campus, Aurora, Colorado.,Department of Psychiatry, University of Colorado Anschutz Medical Campus, Aurora, Colorado.,Research Service, Denver VA Medical Center, Denver, Colorado
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66
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Tang B, Luo D, Yang J, Xu XY, Zhu BL, Wang XF, Yan Z, Chen GJ. Modulation of AMPA receptor mediated current by nicotinic acetylcholine receptor in layer I neurons of rat prefrontal cortex. Sci Rep 2015; 5:14099. [PMID: 26370265 PMCID: PMC4572933 DOI: 10.1038/srep14099] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2015] [Accepted: 08/18/2015] [Indexed: 12/24/2022] Open
Abstract
Layer I neurons in the prefrontal cortex (PFC) exhibit extensive synaptic connections with deep layer neurons, implying their important role in the neural circuit. Study demonstrates that activation of nicotinic acetylcholine receptors (nAChRs) increases excitatory neurotransmission in this layer. Here we found that nicotine selectively increased the amplitude of AMPA receptor (AMPAR)-mediated current and AMPA/NMDA ratio, while without effect on NMDA receptor-mediated current. The augmentation of AMPAR current by nicotine was inhibited by a selective α7-nAChR antagonist methyllycaconitine (MLA) and intracellular calcium chelator BAPTA. In addition, nicotinic effect on mEPSC or paired-pulse ratio was also prevented by MLA. Moreover, an enhanced inward rectification of AMPAR current by nicotine suggested a functional role of calcium permeable and GluA1 containing AMPAR. Consistently, nicotine enhancement of AMPAR current was inhibited by a selective calcium-permeable AMPAR inhibitor IEM-1460. Finally, the intracellular inclusion of synthetic peptide designed to block GluA1 subunit of AMPAR at CAMKII, PKC or PKA phosphorylation site, as well as corresponding kinase inhibitor, blocked nicotinic augmentation of AMPA/NMDA ratio. These results have revealed that nicotine increases AMPAR current by modulating the phosphorylation state of GluA1 which is dependent on α7-nAChR and intracellular calcium.
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Affiliation(s)
- Bo Tang
- Department of Neurology, the First Affiliated Hospital of Chongqing Medical University, Chongqing Key Laboratory of Neurology, 1 Youyi Road, Chongqing 400016, China.,The People's Hospital of Anyue County, 68 Wai-Nan Street, Anyue County, Si-Chuan Province, 642350,China
| | - Dong Luo
- Department of Neurology, the First Affiliated Hospital of Chongqing Medical University, Chongqing Key Laboratory of Neurology, 1 Youyi Road, Chongqing 400016, China
| | - Jie Yang
- Department of Neurology, the First Affiliated Hospital of Chongqing Medical University, Chongqing Key Laboratory of Neurology, 1 Youyi Road, Chongqing 400016, China
| | - Xiao-Yan Xu
- Department of Neurology, the First Affiliated Hospital of Chongqing Medical University, Chongqing Key Laboratory of Neurology, 1 Youyi Road, Chongqing 400016, China
| | - Bing-Lin Zhu
- Department of Neurology, the First Affiliated Hospital of Chongqing Medical University, Chongqing Key Laboratory of Neurology, 1 Youyi Road, Chongqing 400016, China
| | - Xue-Feng Wang
- Department of Neurology, the First Affiliated Hospital of Chongqing Medical University, Chongqing Key Laboratory of Neurology, 1 Youyi Road, Chongqing 400016, China
| | - Zhen Yan
- Department of Physiology and Biophysics, State University of New York at Buffalo, Buffalo, NY, 14214, USA
| | - Guo-Jun Chen
- Department of Neurology, the First Affiliated Hospital of Chongqing Medical University, Chongqing Key Laboratory of Neurology, 1 Youyi Road, Chongqing 400016, China
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67
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Zoli M, Pistillo F, Gotti C. Diversity of native nicotinic receptor subtypes in mammalian brain. Neuropharmacology 2015; 96:302-11. [DOI: 10.1016/j.neuropharm.2014.11.003] [Citation(s) in RCA: 167] [Impact Index Per Article: 18.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2014] [Revised: 10/11/2014] [Accepted: 11/08/2014] [Indexed: 01/01/2023]
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68
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Fox AM, Moonschi FH, Richards CI. The nicotine metabolite, cotinine, alters the assembly and trafficking of a subset of nicotinic acetylcholine receptors. J Biol Chem 2015; 290:24403-12. [PMID: 26269589 DOI: 10.1074/jbc.m115.661827] [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: 04/27/2015] [Indexed: 12/27/2022] Open
Abstract
Exposure to nicotine alters the trafficking and assembly of nicotinic receptors (nAChRs), leading to their up-regulation on the plasma membrane. Although the mechanism is not fully understood, nicotine-induced up-regulation is believed to contribute to nicotine addiction. The effect of cotinine, the primary metabolite of nicotine, on nAChR trafficking and assembly has not been extensively investigated. We utilize a pH-sensitive variant of GFP, super ecliptic pHluorin, to differentiate between intracellular nAChRs and those expressed on the plasma membrane to quantify changes resulting from cotinine and nicotine exposure. Similar to nicotine, exposure to cotinine increases the number of α4β2 receptors on the plasma membrane and causes a redistribution of intracellular receptors. In contrast to this, cotinine exposure down-regulates α6β2β3 receptors. We also used single molecule fluorescence studies to show that cotinine and nicotine both alter the assembly of α4β2 receptors to favor the high sensitivity (α4)2(β2)3 stoichiometry.
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Affiliation(s)
- Ashley M Fox
- From the Department of Chemistry, University of Kentucky, Lexington, Kentucky 40506
| | - Faruk H Moonschi
- From the Department of Chemistry, University of Kentucky, Lexington, Kentucky 40506
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69
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Ly6h regulates trafficking of alpha7 nicotinic acetylcholine receptors and nicotine-induced potentiation of glutamatergic signaling. J Neurosci 2015; 35:3420-30. [PMID: 25716842 DOI: 10.1523/jneurosci.3630-14.2015] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
α7 nAChRs are expressed widely throughout the brain, where they are important for synaptic signaling, gene transcription, and plastic changes that regulate sensory processing, cognition, and neural responses to chronic nicotine exposure. However, the mechanisms by which α7 nAChRs are regulated are poorly understood. Here we show that trafficking of α7-subunits is controlled by endogenous membrane-associated prototoxins in the Ly6 family. In particular, we find that Ly6h reduces cell-surface expression and calcium signaling by α7 nAChRs. We detect Ly6h in several rat brain regions, including the hippocampus, where we find it is both necessary and sufficient to limit the magnitude of α7-mediated currents. Consistent with such a regulatory function, knockdown of Ly6h in rat hippocampal pyramidal neurons enhances nicotine-induced potentiation of glutamatergic mEPSC amplitude, which is known to be mediated by α7 signaling. Collectively our data suggest a novel cellular role for Ly6 proteins in regulating nAChRs, which may be relevant to plastic changes in the nervous system including rewiring of glutamatergic circuitry during nicotine addiction.
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70
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Smucny J, Stevens KE, Olincy A, Tregellas JR. Translational utility of rodent hippocampal auditory gating in schizophrenia research: a review and evaluation. Transl Psychiatry 2015; 5:e587. [PMID: 26101850 PMCID: PMC4490287 DOI: 10.1038/tp.2015.77] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/09/2015] [Revised: 04/14/2015] [Accepted: 05/04/2015] [Indexed: 01/15/2023] Open
Abstract
Impaired gating of the auditory evoked P50 potential is one of the most pharmacologically well-characterized features of schizophrenia. This deficit is most commonly modeled in rodents by implanted electrode recordings from the hippocampus of the rodent analog of the P50, the P20-N40. The validity and effectiveness of this tool, however, has not been systematically reviewed. Here, we summarize findings from studies that have examined the effects of pharmacologic modulation on gating of the rodent hippocampal P20-N40 and the human P50. We show that drug effects on the P20-N40 are highly predictive of human effects across similar dose ranges. Furthermore, mental status (for example, anesthetized vs alert) does not appear to diminish the predictive capacity of these recordings. We then discuss hypothesized neuropharmacologic mechanisms that may underlie gating effects for each drug studied. Overall, this review supports continued use of hippocampal P20-N40 gating as a translational tool for schizophrenia research.
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Affiliation(s)
- J Smucny
- Neuroscience Program, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
- Research Service, Denver VA Medical Center, Denver, CO, USA
- Department of Psychiatry, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - K E Stevens
- Department of Psychiatry, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - A Olincy
- Research Service, Denver VA Medical Center, Denver, CO, USA
- Department of Psychiatry, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - J R Tregellas
- Neuroscience Program, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
- Research Service, Denver VA Medical Center, Denver, CO, USA
- Department of Psychiatry, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
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71
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Natural compounds interacting with nicotinic acetylcholine receptors: from low-molecular weight ones to peptides and proteins. Toxins (Basel) 2015; 7:1683-701. [PMID: 26008231 PMCID: PMC4448168 DOI: 10.3390/toxins7051683] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2015] [Accepted: 05/07/2015] [Indexed: 12/16/2022] Open
Abstract
Nicotinic acetylcholine receptors (nAChRs) fulfill a variety of functions making identification and analysis of nAChR subtypes a challenging task. Traditional instruments for nAChR research are d-tubocurarine, snake venom protein α-bungarotoxin (α-Bgt), and α-conotoxins, neurotoxic peptides from Conus snails. Various new compounds of different structural classes also interacting with nAChRs have been recently identified. Among the low-molecular weight compounds are alkaloids pibocin, varacin and makaluvamines C and G. 6-Bromohypaphorine from the mollusk Hermissenda crassicornis does not bind to Torpedo nAChR but behaves as an agonist on human α7 nAChR. To get more selective α-conotoxins, computer modeling of their complexes with acetylcholine-binding proteins and distinct nAChRs was used. Several novel three-finger neurotoxins targeting nAChRs were described and α-Bgt inhibition of GABA-A receptors was discovered. Information on the mechanisms of nAChR interactions with the three-finger proteins of the Ly6 family was found. Snake venom phospholipases A2 were recently found to inhibit different nAChR subtypes. Blocking of nAChRs in Lymnaea stagnalis neurons was shown for venom C-type lectin-like proteins, appearing to be the largest molecules capable to interact with the receptor. A huge nAChR molecule sensible to conformational rearrangements accommodates diverse binding sites recognizable by structurally very different compounds.
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72
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Wu WL, Adams CE, Stevens KE, Chow KH, Freedman R, Patterson PH. The interaction between maternal immune activation and alpha 7 nicotinic acetylcholine receptor in regulating behaviors in the offspring. Brain Behav Immun 2015; 46:192-202. [PMID: 25683697 PMCID: PMC4414803 DOI: 10.1016/j.bbi.2015.02.005] [Citation(s) in RCA: 64] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/15/2014] [Revised: 01/16/2015] [Accepted: 02/01/2015] [Indexed: 12/22/2022] Open
Abstract
Mutation of human chromosome 15q13.3 increases the risk for autism and schizophrenia. One of the noteworthy genes in 15q13.3 is CHRNA7, which encodes the nicotinic acetylcholine receptor alpha 7 subunit (α7nAChR) associated with schizophrenia in clinical studies and rodent models. This study investigates the role of α7nAChR in maternal immune activation (MIA) mice model, a murine model of environmental risk factor for autism and schizophrenia. We provided choline, a selective α7nAChR agonist among its several developmental roles, in the diet of C57BL/6N wild-type dams throughout the gestation and lactation period and induced MIA at mid-gestation. The adult offspring behavior and gene expression profile in the maternal-placental-fetal axis at mid-gestation were investigated. We found that choline supplementation prevented several MIA-induced behavioral abnormalities in the wild-type offspring. Pro-inflammatory cytokine interleukin-6 (Il6) and Chrna7 gene expression in the wild-type fetal brain were elevated by poly(I:C) injection and were suppressed by gestational choline supplementation. We further investigated the gene expression level of Il6 in Chrna7 mutant mice. We found that the basal level of Il6 was higher in Chrna7 mutant fetal brain, which suggests that α7nAChR may serve an anti-inflammatory role in the fetal brain during development. Lastly, we induced MIA in Chrna7(+/-) offspring. The Chrna7(+/-) offspring were more vulnerable to MIA, with increased behavioral abnormalities. Our study shows that α7nAChR modulates inflammatory response affecting the fetal brain and demonstrates its effects on offspring behavior development after MIA.
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Affiliation(s)
- Wei-Li Wu
- Division of Biology and Biological Engineering, California Institute of Technology, 1200 E. California Blvd., Pasadena, CA 91125, USA.
| | - Catherine E. Adams
- Denver VA Medical Center, 1055 Clermont St., Denver, CO 80220,Department of Psychiatry, University of Colorado Denver Anschutz Medical Campus, 12800 E. 19th Ave., Aurora, CO 80045
| | - Karen E. Stevens
- Department of Psychiatry, University of Colorado Denver Anschutz Medical Campus, 12800 E. 19th Ave., Aurora, CO 80045
| | - Ke-Huan Chow
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, 91125, USA
| | - Robert Freedman
- Department of Psychiatry, University of Colorado Denver Anschutz Medical Campus, 12800 E. 19th Ave., Aurora, CO 80045
| | - Paul H. Patterson
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, 91125, USA
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73
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Abstract
The glutamatergic subthalamic nucleus (STN) exerts control over motor output through nuclei of the basal ganglia. High-frequency electrical stimuli in the STN effectively alleviate motor symptoms in movement disorders, and cholinergic stimulation boosts this effect. To gain knowledge about the mechanisms of cholinergic modulation in the STN, we studied cellular and circuit aspects of nicotinic acetylcholine receptors (nAChRs) in mouse STN. We discovered two largely divergent microcircuits in the STN; these are regulated in part by either α4β2 or α7 nAChRs. STN neurons containing α4β2 nAChRs (α4β2 neurons) received more glutamatergic inputs, and preferentially innervated GABAergic neurons in the substantia nigra pars reticulata. In contrast, STN neurons containing α7 nAChRs (α7 neurons) received more GABAergic inputs, and preferentially innervated dopaminergic neurons in the substantia nigra pars compacta. Interestingly, local electrical stimuli excited a majority (79%) of α4β2 neurons but exerted strong inhibition in 58% of α7 neurons, indicating an additional diversity of STN neurons: responses to electrical stimulation. Chronic exposure to nicotine selectively affects α4β2 nAChRs in STN: this treatment increased the number of α4β2 neurons, upregulated α4-containing nAChR number and sensitivity, and enhanced the basal firing rate of α4β2 neurons both ex vivo and in vivo. Thus, chronic nicotine enhances the function of the microcircuit involving α4β2 nAChRs. This indicates chronic exposure to nicotinic agonist as a potential pharmacological intervention to alter selectively the balance between these two microcircuits, and may provide a means to inhibit substantia nigra dopaminergic neurons.
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74
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Akinrinade ID, Memudu AE, Ogundele OM. Fluoride and aluminium disturb neuronal morphology, transport functions, cholinesterase, lysosomal and cell cycle activities. ACTA ACUST UNITED AC 2015; 22:105-15. [PMID: 25863844 DOI: 10.1016/j.pathophys.2015.03.001] [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] [Received: 09/15/2014] [Revised: 03/12/2015] [Accepted: 03/25/2015] [Indexed: 02/05/2023]
Abstract
UNLABELLED Fluoride and aluminium have been reported to cause severe alterations in the brain. However, their exact mechanisms of neurotoxic activities remain unknown. AIM This study was designed to investigate the role of fluoride and aluminium in neuronal transport, lysosomal, cell cycle protein and acetylcholinesterase activities. METHOD Adult Wistar rats were given low and high doses of fluoride, aluminium and a combination of both with the control group receiving distilled water for 30 days. Blood sera and brain homogenates were quantified for alkaline phosphatase (biomarker for neuronal transport) activities. Brain sections were stained with cresyl fast violet to detect neuronal cell damage. Histochemical demonstration of acetylcholinesterase (AChE) activity and the immunohistochemical detection of cell cycle protein (anti-cyclin D) and lysosomal protein (anti-cathepsin D) were done using the antigen retrieval method. RESULT Results showed severe histomorphologic alterations, dysregulation of membrane transport activities, inhibition of AChE activities and increased expression of lysosomal and cell cycle proteins. CONCLUSION These findings confirm that excessive fluoride and aluminium intake induces the progression of cell death which inhibit AChE activities and trigger the release of lysosomal and cell cycle proteins.
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Affiliation(s)
- Ibukun Dorcas Akinrinade
- Department of Anatomy, College of Health Sciences, Bingham University, P.M.B. 005, New Karu 961106, Nasarawa State, Nigeria.
| | - Adejoke Elizabeth Memudu
- Department of Anatomy, College of Health Sciences, Bingham University, P.M.B. 005, New Karu 961106, Nasarawa State, Nigeria.
| | - Olalekan Michael Ogundele
- Neural Systems Lab, Department of Comparative Biomedical Sciences, Louisiana State University, Baten Rouge 70802, LA, USA.
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75
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Jiang L, López-Hernández GY, Lederman J, Talmage DA, Role LW. Optogenetic studies of nicotinic contributions to cholinergic signaling in the central nervous system. Rev Neurosci 2015; 25:755-71. [PMID: 25051276 DOI: 10.1515/revneuro-2014-0032] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2014] [Accepted: 06/27/2014] [Indexed: 11/15/2022]
Abstract
Molecular manipulations and targeted pharmacological studies provide a compelling picture of which nicotinic receptor subtypes are where in the central nervous system (CNS) and what happens if one activates or deletes them. However, understanding the physiological contribution of nicotinic receptors to endogenous acetylcholine (ACh) signaling in the CNS has proven a more difficult problem to solve. In this review, we provide a synopsis of the literature on the use of optogenetic approaches to control the excitability of cholinergic neurons and to examine the role of CNS nicotinic ACh receptors (nAChRs). As is often the case, this relatively new technology has answered some questions and raised others. Overall, we believe that optogenetic manipulation of cholinergic excitability in combination with some rigorous pharmacology will ultimately advance our understanding of the many functions of nAChRs in the brain.
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76
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Henderson BJ, Lester HA. Inside-out neuropharmacology of nicotinic drugs. Neuropharmacology 2015; 96:178-93. [PMID: 25660637 DOI: 10.1016/j.neuropharm.2015.01.022] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2014] [Revised: 01/20/2015] [Accepted: 01/20/2015] [Indexed: 02/05/2023]
Abstract
Upregulation of neuronal nicotinic acetylcholine receptors (AChRs) is a venerable result of chronic exposure to nicotine; but it is one of several consequences of pharmacological chaperoning by nicotine and by some other nicotinic ligands, especially agonists. Nicotinic ligands permeate through cell membranes, bind to immature AChR oligomers, elicit incompletely understood conformational reorganizations, increase the interaction between adjacent AChR subunits, and enhance the maturation process toward stable AChR pentamers. These changes and stabilizations in turn lead to increases in both anterograde and retrograde traffic within the early secretory pathway. In addition to the eventual upregulation of AChRs at the plasma membrane, other effects of pharmacological chaperoning include modifications to endoplasmic reticulum stress and to the unfolded protein response. Because these processes depend on pharmacological chaperoning within intracellular organelles, we group them as "inside-out pharmacology". This term contrasts with the better-known, acute, "outside-in" effects of activating and desensitizing plasma membrane AChRs. We review current knowledge concerning the mechanisms and consequences of inside-out pharmacology. This article is part of the Special Issue entitled 'The Nicotinic Acetylcholine Receptor: From Molecular Biology to Cognition'.
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Affiliation(s)
- Brandon J Henderson
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| | - Henry A Lester
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA.
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77
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Saika F, Kiguchi N, Kobayashi Y, Kishioka S. Peripheral alpha4beta2 nicotinic acetylcholine receptor signalling attenuates tactile allodynia and thermal hyperalgesia after nerve injury in mice. Acta Physiol (Oxf) 2015; 213:462-71. [PMID: 25491757 DOI: 10.1111/apha.12437] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2014] [Revised: 07/22/2014] [Accepted: 12/02/2014] [Indexed: 01/03/2023]
Abstract
AIM Neuropathic pain is often refractory to conventional analgesics including opioids and non-steroidal anti-inflammatory drugs. Evidence suggests nicotinic acetylcholine receptor ligands regulate pain transmission. Effects of α4β2 nicotinic acetylcholine receptor activation on pain behaviours after nerve injury were studied. METHODS Mice were subjected to partial sciatic nerve ligation (PSL). Nicotinic acetylcholine receptor α4 and β2 subunits localization in injured nerves were evaluated by immunohistochemistry. Neuropathic pain, assessed by tactile allodynia and thermal hyperalgesia, was examined by von Frey test and Hargreaves test respectively. RESULTS Nicotinic acetylcholine receptor α4 and β2 subunits were up-regulated in injured nerves and were expressed on F4/80-positive macrophages. When nicotine was perineurally administered daily for 4 days (day 7-10; maintenance phase) after nerve injury, pain behaviours were significantly alleviated. The inhibitory effects of nicotine were reversed by co-administration of mecamylamine (non-selective nicotinic acetylcholine receptor antagonist) and dihydro-β-erythroidine (selective α4β2 nicotinic acetylcholine receptor antagonist). Likewise, when α4β2 nicotinic acetylcholine receptor agonists (TC2559 or ABT418) were administered daily for 4 days (day 7-10) after nerve injury, pain behaviours were significantly attenuated. On the other hand, nicotine administered daily for 4 days (day 0-3; initiation phase) after nerve injury alleviated pain behaviours, which were antagonized by co-administration of dihydro-β-erythroidine. TC2559 administered daily for 4 days (day 0-3) also attenuated nerve injury-induced pain behaviours. CONCLUSION The activation of α4β2 nicotinic acetylcholine receptor expressed on infiltrating macrophages in injured nerves may participate in the relief of PSL-induced neuropathic pain during maintenance and initiation phases.
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Affiliation(s)
- F. Saika
- Department of Pharmacology; Wakayama Medical University; Wakayama Japan
| | - N. Kiguchi
- Department of Pharmacology; Wakayama Medical University; Wakayama Japan
| | - Y. Kobayashi
- Department of Pharmacology; Wakayama Medical University; Wakayama Japan
| | - S. Kishioka
- Department of Pharmacology; Wakayama Medical University; Wakayama Japan
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78
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Keighron JD, Wigström J, Kurczy ME, Bergman J, Wang Y, Cans AS. Amperometric detection of single vesicle acetylcholine release events from an artificial cell. ACS Chem Neurosci 2015; 6:181-8. [PMID: 25565357 DOI: 10.1021/cn5002667] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
Acetylcholine is a highly abundant nonelectroactive neurotransmitter in the mammalian central nervous system. Neurochemical release occurs on the millisecond time scale, requiring a fast, sensitive sensor such as an enzymatic amperometric electrode. Typically, the enzyme used for enzymatic electrochemical sensors is applied in excess to maximize signal. Here, in addition to sensitivity, we have also sought to maximize temporal resolution, by designing a sensor that is sensitive enough to work at near monolayer enzyme coverage. Reducing the enzyme layer thickness increases sensor temporal resolution by decreasing the distance and reducing the diffusion time for the enzyme product to travel to the sensor surface for detection. In this instance, the sensor consists of electrodeposited gold nanoparticle modified carbon fiber microelectrodes (CFMEs). Enzymes often are sensitive to curvature upon surface adsorption; thus, it was important to deposit discrete nanoparticles to maintain enzyme activity while depositing as much gold as possible to maximize enzyme coverage. To further enhance sensitivity, the enzymes acetylcholinesterase (AChE) and choline oxidase (ChO) were immobilized onto the gold nanoparticles at the previously determined optimal ratio (1:10 AChE/ChO) for most efficient sequential enzymatic activity. This optimization approach has enabled the rapid detection to temporally resolve single vesicle acetylcholine release from an artificial cell. The sensor described is a significant advancement in that it allows for the recording of acetylcholine release on the order of the time scale for neurochemical release in secretory cells.
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Affiliation(s)
- Jacqueline D. Keighron
- Department
of Chemical and Biological Engineering, Chalmers University of Technology, 41296 Gothenburg, Sweden
| | - Joakim Wigström
- Department
of Chemical and Biological Engineering, Chalmers University of Technology, 41296 Gothenburg, Sweden
| | - Michael E. Kurczy
- Department
of Chemical and Biological Engineering, Chalmers University of Technology, 41296 Gothenburg, Sweden
| | - Jenny Bergman
- Department
of Chemistry and Molecular Biology, University of Gothenburg, 41296 Gothenburg, Sweden
| | - Yuanmo Wang
- Department
of Chemical and Biological Engineering, Chalmers University of Technology, 41296 Gothenburg, Sweden
| | - Ann-Sofie Cans
- Department
of Chemical and Biological Engineering, Chalmers University of Technology, 41296 Gothenburg, Sweden
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79
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Jensen MM, Arvaniti M, Mikkelsen JD, Michalski D, Pinborg LH, Härtig W, Thomsen MS. Prostate stem cell antigen interacts with nicotinic acetylcholine receptors and is affected in Alzheimer's disease. Neurobiol Aging 2015; 36:1629-1638. [PMID: 25680266 DOI: 10.1016/j.neurobiolaging.2015.01.001] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2014] [Revised: 12/08/2014] [Accepted: 01/03/2015] [Indexed: 01/13/2023]
Abstract
Alzheimer's disease (AD) is a neurodegenerative disorder involving impaired cholinergic neurotransmission and dysregulation of nicotinic acetylcholine receptors (nAChRs). Ly-6/neurotoxin (Lynx) proteins have been shown to modulate cognition and neural plasticity by binding to nAChR subtypes and modulating their function. Hence, changes in nAChR regulatory proteins such as Lynx proteins could underlie the dysregulation of nAChRs in AD. Using Western blotting, we detected bands corresponding to the Lynx proteins prostate stem cell antigen (PSCA) and Lypd6 in human cortex indicating that both proteins are present in the human brain. We further showed that PSCA forms stable complexes with the α4 nAChR subunit and decreases nicotine-induced extracellular-signal regulated kinase phosphorylation in PC12 cells. In addition, we analyzed protein levels of PSCA and Lypd6 in postmortem tissue of medial frontal gyrus from AD patients and found significantly increased PSCA levels (approximately 70%). In contrast, no changes in Lypd6 levels were detected. In concordance with our findings in AD patients, PSCA levels were increased in the frontal cortex of triple transgenic mice with an AD-like pathology harboring human transgenes that cause both age-dependent β-amyloidosis and tauopathy, whereas Tg2576 mice, which display β-amyloidosis only, had unchanged PSCA levels compared to wild-type animals. These findings identify PSCA as a nAChR-binding protein in the human brain that is affected in AD, suggesting that PSCA-nAChR interactions may be involved in the cognitive dysfunction observed in AD.
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Affiliation(s)
- Majbrit M Jensen
- Neurobiology Research Unit, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark
| | - Maria Arvaniti
- Neurobiology Research Unit, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark
| | - Jens D Mikkelsen
- Neurobiology Research Unit, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark
| | | | - Lars H Pinborg
- Neurobiology Research Unit, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark; Epilepsy Clinic, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark
| | - Wolfgang Härtig
- Paul Flechsig Institute for Brain Research, University of Leipzig, Leipzig, Germany
| | - Morten S Thomsen
- Neurobiology Research Unit, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark.
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80
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Smucny J, Visani A, Tregellas JR. Could vagus nerve stimulation target hippocampal hyperactivity to improve cognition in schizophrenia? Front Psychiatry 2015; 6:43. [PMID: 25852579 PMCID: PMC4371554 DOI: 10.3389/fpsyt.2015.00043] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/21/2015] [Accepted: 03/10/2015] [Indexed: 01/26/2023] Open
Affiliation(s)
- Jason Smucny
- Neuroscience Program, University of Colorado Anschutz Medical Campus , Aurora, CO , USA ; Research Service, Denver Veterans Affairs Medical Center , Denver, CO , USA ; Department of Psychiatry, University of Colorado Anschutz Medical Campus , Aurora, CO , USA
| | - Adrienne Visani
- Department of Psychiatry, University of Colorado Anschutz Medical Campus , Aurora, CO , USA
| | - Jason R Tregellas
- Neuroscience Program, University of Colorado Anschutz Medical Campus , Aurora, CO , USA ; Research Service, Denver Veterans Affairs Medical Center , Denver, CO , USA ; Department of Psychiatry, University of Colorado Anschutz Medical Campus , Aurora, CO , USA
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81
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Javitt DC, Freedman R. Sensory processing dysfunction in the personal experience and neuronal machinery of schizophrenia. Am J Psychiatry 2015; 172:17-31. [PMID: 25553496 PMCID: PMC4501403 DOI: 10.1176/appi.ajp.2014.13121691] [Citation(s) in RCA: 263] [Impact Index Per Article: 29.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Sensory processing deficits, first investigated by Kraepelin and Bleuler as possible pathophysiological mechanisms in schizophrenia, are now being recharacterized in the context of our current understanding of the molecular and neurobiological brain mechanisms involved. The National Institute of Mental Health Research Domain Criteria position these deficits as intermediaries between molecular and cellular mechanisms and clinical symptoms of schizophrenia, such as hallucinations. The prepulse inhibition of startle responses by a weaker preceding tone, the inhibitory gating of response to paired sensory stimuli characterized using the auditory P50 evoked response, and the detection of slight deviations in patterns of sensory stimulation eliciting the cortical mismatch negativity potential demonstrate deficits in early sensory processing mechanisms, whose molecular and neurobiological bases are increasingly well understood. Deficits in sensory processing underlie more complex cognitive dysfunction and are in turn affected by higher-level cognitive difficulties. These deficits are now being used to identify genes involved in familial transmission of schizophrenia and to monitor potentially therapeutic drug effects for both treatment and prevention. This research also provides a clinical reminder that patients' sensory perception of the surrounding world, even during treatment sessions, may differ considerably from others' perceptions. A person's ability to understand and interact effectively with the surrounding world ultimately depends on an underlying sensory experience of it.
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Affiliation(s)
- Daniel C. Javitt
- Division of Experimental Therapeutics, Department of Psychiatry, Program in Cognitive Neuroscience and Schizophrenia, Nathan Kline Institute for Psychiatric Research/Columbia University Medical Center, New York, NY 10032, USA
| | - Robert Freedman
- Department of Psychiatry, University of Colorado Denver School of Medicine, Mail Stop F546, Aurora, CO, 80045, USA
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82
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Three-finger snake neurotoxins and Ly6 proteins targeting nicotinic acetylcholine receptors: pharmacological tools and endogenous modulators. Trends Pharmacol Sci 2014; 36:109-23. [PMID: 25528970 DOI: 10.1016/j.tips.2014.11.003] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2014] [Revised: 11/04/2014] [Accepted: 11/10/2014] [Indexed: 02/07/2023]
Abstract
Snake venom neurotoxins and lymphocyte antigen 6 (Ly6) proteins, most of the latter being membrane tethered by a glycosylphosphatidylinositol (GPI) anchor, have a variety of biological activities, but their three-finger (3F) folding combines them in one Ly6/neurotoxin family. Subsets of two groups, represented by α-neurotoxins and Lynx1, respectively, interact with nicotinic acetylcholine receptors (nAChR) and, hence, are of therapeutic interest for the treatment of neurodegenerative diseases, pain, and cancer. Information on the mechanisms of action and 3D structure of the binding sites, which is required for drug design, is available from the 3D structure of α-neurotoxin complexes with nAChR models. Here, I compare the structural and functional features of α-neurotoxins versus Lynx1 and its homologs to get a clearer picture of Lynx1-nAChR interactions that is necessary for fundamental science and practical applications.
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83
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Nichols WA, Henderson BJ, Yu C, Parker RL, Richards CI, Lester HA, Miwa JM. Lynx1 shifts α4β2 nicotinic receptor subunit stoichiometry by affecting assembly in the endoplasmic reticulum. J Biol Chem 2014; 289:31423-32. [PMID: 25193667 PMCID: PMC4223341 DOI: 10.1074/jbc.m114.573667] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2014] [Revised: 08/30/2014] [Indexed: 01/11/2023] Open
Abstract
Glycosylphosphatidylinositol-anchored neurotoxin-like receptor binding proteins, such as lynx modulators, are topologically positioned to exert pharmacological effects by binding to the extracellular portion of nAChRs. These actions are generally thought to proceed when both lynx and the nAChRs are on the plasma membrane. Here, we demonstrate that lynx1 also exerts effects on α4β2 nAChRs within the endoplasmic reticulum. Lynx1 affects assembly of nascent α4 and β2 subunits and alters the stoichiometry of the receptor population that reaches the plasma membrane. Additionally, these data suggest that lynx1 shifts nAChR stoichiometry to low sensitivity (α4)3(β2)2 pentamers primarily through this interaction in the endoplasmic reticulum, rather than solely via direct modulation of activity on the plasma membrane. To our knowledge, these data represent the first test of the hypothesis that a lynx family member, or indeed any glycosylphosphatidylinositol-anchored protein, could act within the cell to alter assembly of a multisubunit protein.
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Affiliation(s)
- Weston A Nichols
- From the Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91125
| | - Brandon J Henderson
- From the Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91125
| | - Caroline Yu
- From the Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91125
| | - Rell L Parker
- From the Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91125
| | | | - Henry A Lester
- From the Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91125
| | - Julie M Miwa
- From the Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91125, the Department of Biological Sciences, Lehigh University, Bethlehem, Pennsylvania 18015
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84
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Hamaneh MB, Yu YK. Relating diseases by integrating gene associations and information flow through protein interaction network. PLoS One 2014; 9:e110936. [PMID: 25360770 PMCID: PMC4216010 DOI: 10.1371/journal.pone.0110936] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2014] [Accepted: 09/27/2014] [Indexed: 12/31/2022] Open
Abstract
Identifying similar diseases could potentially provide deeper understanding of their underlying causes, and may even hint at possible treatments. For this purpose, it is necessary to have a similarity measure that reflects the underpinning molecular interactions and biological pathways. We have thus devised a network-based measure that can partially fulfill this goal. Our method assigns weights to all proteins (and consequently their encoding genes) by using information flow from a disease to the protein interaction network and back. Similarity between two diseases is then defined as the cosine of the angle between their corresponding weight vectors. The proposed method also provides a way to suggest disease-pathway associations by using the weights assigned to the genes to perform enrichment analysis for each disease. By calculating pairwise similarities between 2534 diseases, we show that our disease similarity measure is strongly correlated with the probability of finding the diseases in the same disease family and, more importantly, sharing biological pathways. We have also compared our results to those of MimMiner, a text-mining method that assigns pairwise similarity scores to diseases. We find the results of the two methods to be complementary. It is also shown that clustering diseases based on their similarities and performing enrichment analysis for the cluster centers significantly increases the term association rate, suggesting that the cluster centers are better representatives for biological pathways than the diseases themselves. This lends support to the view that our similarity measure is a good indicator of relatedness of biological processes involved in causing the diseases. Although not needed for understanding this paper, the raw results are available for download for further study at ftp://ftp.ncbi.nlm.nih.gov/pub/qmbpmn/DiseaseRelations/.
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Affiliation(s)
- Mehdi Bagheri Hamaneh
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD, United States of America
| | - Yi-Kuo Yu
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD, United States of America
- * E-mail:
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85
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Alexander SPH, Benson HE, Faccenda E, Pawson AJ, Sharman JL, Spedding M, Peters JA, Harmar AJ. The Concise Guide to PHARMACOLOGY 2013/14: ligand-gated ion channels. Br J Pharmacol 2014; 170:1582-606. [PMID: 24528238 PMCID: PMC3892288 DOI: 10.1111/bph.12446] [Citation(s) in RCA: 113] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The Concise Guide to PHARMACOLOGY 2013/14 provides concise overviews of the key properties of over 2000 human drug targets with their pharmacology, plus links to an open access knowledgebase of drug targets and their ligands (www.guidetopharmacology.org), which provides more detailed views of target and ligand properties. The full contents can be found at http://onlinelibrary.wiley.com/doi/10.1111/bph.12444/full. Ligand-gated ion channels are one of the seven major pharmacological targets into which the Guide is divided, with the others being G protein-coupled receptors, ion channels, catalytic receptors, nuclear hormone receptors, transporters and enzymes. These are presented with nomenclature guidance and summary information on the best available pharmacological tools, alongside key references and suggestions for further reading. A new landscape format has easy to use tables comparing related targets. It is a condensed version of material contemporary to late 2013, which is presented in greater detail and constantly updated on the website www.guidetopharmacology.org, superseding data presented in previous Guides to Receptors and Channels. It is produced in conjunction with NC-IUPHAR and provides the official IUPHAR classification and nomenclature for human drug targets, where appropriate. It consolidates information previously curated and displayed separately in IUPHAR-DB and the Guide to Receptors and Channels, providing a permanent, citable, point-in-time record that will survive database updates.
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Affiliation(s)
- Stephen P H Alexander
- School of Life Sciences, University of Nottingham Medical School, Nottingham, NG7 2UH, UK
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86
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Jensen AB, Hoestgaard-Jensen K, Jensen AA. Pharmacological characterisation of α6β4⁎ nicotinic acetylcholine receptors assembled from three chimeric α6/α3 subunits in tsA201 cells. Eur J Pharmacol 2014; 740:703-13. [DOI: 10.1016/j.ejphar.2014.06.005] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2014] [Revised: 05/19/2014] [Accepted: 06/01/2014] [Indexed: 02/05/2023]
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87
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Henderson BJ, Srinivasan R, Nichols WA, Dilworth CN, Gutierrez DF, Mackey EDW, McKinney S, Drenan RM, Richards CI, Lester HA. Nicotine exploits a COPI-mediated process for chaperone-mediated up-regulation of its receptors. ACTA ACUST UNITED AC 2014; 143:51-66. [PMID: 24378908 PMCID: PMC3874574 DOI: 10.1085/jgp.201311102] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Chronic exposure to nicotine up-regulates high sensitivity nicotinic acetylcholine receptors (nAChRs) in the brain. This up-regulation partially underlies addiction and may also contribute to protection against Parkinson's disease. nAChRs containing the α6 subunit (α6* nAChRs) are expressed in neurons in several brain regions, but comparatively little is known about the effect of chronic nicotine on these nAChRs. We report here that nicotine up-regulates α6* nAChRs in several mouse brain regions (substantia nigra pars compacta, ventral tegmental area, medial habenula, and superior colliculus) and in neuroblastoma 2a cells. We present evidence that a coat protein complex I (COPI)-mediated process mediates this up-regulation of α6* or α4* nAChRs but does not participate in basal trafficking. We show that α6β2β3 nAChR up-regulation is prevented by mutating a putative COPI-binding motif in the β3 subunit or by inhibiting COPI. Similarly, a COPI-dependent process is required for up-regulation of α4β2 nAChRs by chronic nicotine but not for basal trafficking. Mutation of the putative COPI-binding motif or inhibition of COPI also results in reduced normalized Förster resonance energy transfer between α6β2β3 nAChRs and εCOP subunits. The discovery that nicotine exploits a COPI-dependent process to chaperone high sensitivity nAChRs is novel and suggests that this may be a common mechanism in the up-regulation of nAChRs in response to chronic nicotine.
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Affiliation(s)
- Brandon J Henderson
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125
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88
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Wang Y, Xiao C, Indersmitten T, Freedman R, Leonard S, Lester HA. The duplicated α7 subunits assemble and form functional nicotinic receptors with the full-length α7. J Biol Chem 2014; 289:26451-26463. [PMID: 25056953 DOI: 10.1074/jbc.m114.582858] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The α7 nicotinic acetylcholine receptor gene (CHRNA7) is linked to schizophrenia. A partial duplication of CHRNA7 (CHRFAM7A) is found in humans on 15q13-14. Exon 6 of CHRFAM7A harbors a 2-bp deletion polymorphism, CHRFAM7AΔ2bp, which is also associated with schizophrenia. To understand the effects of the duplicated subunits on α7 receptors, we fused α7, dupα7, and dupΔα7 subunits with various fluorescent proteins. The duplicated subunits co-localized with full-length α7 subunits in mouse neuroblastoma cells (Neuro2a) as well as rat hippocampal neurons. We investigated the interaction between the duplicated subunits and full-length α7 by measuring Förster resonance energy transfer using donor recovery after photobleaching and fluorescence lifetime imaging microscopy. The results revealed that the duplicated proteins co-assemble with α7. In electrophysiological studies, Leu at the 9'-position in the M2 membrane-spanning segment was replaced with Cys in dupα7 or dupΔα7, and constructs were co-transfected with full-length α7 in Neuro2a cells. Exposure to ethylammonium methanethiosulfonate inhibited acetylcholine-induced currents, showing that the assembled functional nicotinic acetylcholine receptors (nAChRs) included the duplicated subunit. Incorporation of dupα7 and dupΔα7 subunits modestly changes the sensitivity of receptors to choline and varenicline. Thus, the duplicated proteins are assembled and transported to the cell membrane together with full-length α7 subunits and alter the function of the nAChRs. The characterization of dupα7 and dupΔα7 as well as their influence on α7 nAChRs may help explain the pathophysiology of schizophrenia and may suggest therapeutic strategies.
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Affiliation(s)
- Ying Wang
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91125 and
| | - Cheng Xiao
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91125 and
| | - Tim Indersmitten
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91125 and
| | - Robert Freedman
- Department of Psychiatry, University of Colorado at Denver, Denver, Colorado 80045
| | - Sherry Leonard
- Department of Psychiatry, University of Colorado at Denver, Denver, Colorado 80045
| | - Henry A Lester
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91125 and.
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89
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Kobayashi A, Parker RL, Wright AP, Brahem H, Ku P, Oliver KM, Walz A, Lester HA, Miwa JM. Lynx1 supports neuronal health in the mouse dorsal striatum during aging: an ultrastructural investigation. J Mol Neurosci 2014; 53:525-36. [PMID: 25027556 DOI: 10.1007/s12031-014-0352-1] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2013] [Accepted: 06/09/2014] [Indexed: 10/25/2022]
Abstract
Nicotinic acetylcholine receptors have been shown to participate in neuroprotection in the aging brain. Lynx protein modulators dampen the activity of the cholinergic system through direct interaction with nicotinic receptors. Although lynx1 null mutant mice exhibit augmented learning and plasticity, they also exhibit macroscopic vacuolation in the dorsal striatum as they age, detectable at the optical microscope level. Despite the relevance of the lynx1 gene to brain function, little is known about the cellular ultrastructure of these age-related changes. In this study, we assessed degeneration in the dorsal striatum in 1-, 3-, 7-, and 13-month-old mice, using optical and transmission electron microscopy. We observed a loss of nerve fibers, a breakdown in nerve fiber bundles, and a loss of neuronal nuclei in the 13-month-old lynx1 null striatum. At higher magnification, these nerve fibers displayed intracellular vacuoles and disordered myelin sheaths. Few or none of these morphological alterations were present in younger lynx1 null mutant mice or in heterozygous lynx1 null mutant mice at any age. These data indicate that neuronal health can be maintained by titrating lynx1 dosage and that the lynx1 gene may participate in a trade-off between neuroprotection and augmented learning.
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Affiliation(s)
- Atsuko Kobayashi
- Biology Division, California Institute of Technology, MC156-29, 1200 E. California Blvd., Pasadena, CA, 91125, USA
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90
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Lin H, Hsu FC, Baumann BH, Coulter DA, Anderson SA, Lynch DR. Cortical parvalbumin GABAergic deficits with α7 nicotinic acetylcholine receptor deletion: implications for schizophrenia. Mol Cell Neurosci 2014; 61:163-75. [PMID: 24983521 DOI: 10.1016/j.mcn.2014.06.007] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2014] [Revised: 05/23/2014] [Accepted: 06/16/2014] [Indexed: 11/25/2022] Open
Abstract
Dysfunction of cortical parvalbumin (PV)-containing GABAergic interneurons has been implicated in cognitive deficits of schizophrenia. In humans microdeletion of the CHRNA7 (α7 nicotinic acetylcholine receptor, nAChR) gene is associated with cortical dysfunction in a broad spectrum of neurodevelopmental and neuropsychiatric disorders including schizophrenia while in mice similar deletion causes analogous abnormalities including impaired attention, working-memory and learning. However, the pathophysiological roles of α7 nAChRs in cortical PV GABAergic development remain largely uncharacterized. In both in vivo and in vitro models, we identify here that deletion of the α7 nAChR gene in mice impairs cortical PV GABAergic development and recapitulates many of the characteristic neurochemical deficits in PV-positive GABAergic interneurons found in schizophrenia. α7 nAChR null mice had decreased cortical levels of GABAergic markers including PV, glutamic acid decarboxylase 65/67 (GAD65/67) and the α1 subunit of GABAA receptors, particularly reductions of PV and GAD67 levels in cortical PV-positive interneurons during late postnatal life and adulthood. Cortical GABAergic synaptic deficits were identified in the prefrontal cortex of α7 nAChR null mice and α7 nAChR null cortical cultures. Similar disruptions in development of PV-positive GABAergic interneurons and perisomatic synapses were found in cortical cultures lacking α7 nAChRs. Moreover, NMDA receptor expression was reduced in GABAergic interneurons, implicating NMDA receptor hypofunction in GABAergic deficits in α7 nAChR null mice. Our findings thus demonstrate impaired cortical PV GABAergic development and multiple characteristic neurochemical deficits reminiscent of schizophrenia in cortical PV-positive interneurons in α7 nAChR gene deletion models. This implicates crucial roles of α7 nAChRs in cortical PV GABAergic development and dysfunction in schizophrenia and other neuropsychiatric disorders.
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Affiliation(s)
- Hong Lin
- Department of Pediatrics, The Children's Hospital of Philadelphia, Philadelphia, PA 19104, United States; Department of Neurology, The Children's Hospital of Philadelphia, Philadelphia, PA 19104, United States
| | - Fu-Chun Hsu
- Department of Pediatrics, The Children's Hospital of Philadelphia, Philadelphia, PA 19104, United States; Department of Neurology, The Children's Hospital of Philadelphia, Philadelphia, PA 19104, United States
| | - Bailey H Baumann
- Department of Pediatrics, The Children's Hospital of Philadelphia, Philadelphia, PA 19104, United States; Department of Neurology, The Children's Hospital of Philadelphia, Philadelphia, PA 19104, United States
| | - Douglas A Coulter
- Department of Pediatrics, The Children's Hospital of Philadelphia, Philadelphia, PA 19104, United States; Department of Neurology, The Children's Hospital of Philadelphia, Philadelphia, PA 19104, United States; Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, United States
| | - Stewart A Anderson
- Department of Pediatrics, The Children's Hospital of Philadelphia, Philadelphia, PA 19104, United States; Department of Child Psychiatry, The Children's Hospital of Philadelphia, Philadelphia, PA 19104, United States; Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, United States
| | - David R Lynch
- Department of Pediatrics, The Children's Hospital of Philadelphia, Philadelphia, PA 19104, United States; Department of Neurology, The Children's Hospital of Philadelphia, Philadelphia, PA 19104, United States; Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, United States.
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91
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Feng L, Uteshev VV. Projection target-specific action of nicotine in the caudal nucleus of the solitary tract. J Neurosci Res 2014; 92:1560-72. [PMID: 24975270 DOI: 10.1002/jnr.23436] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2014] [Revised: 05/11/2014] [Accepted: 05/20/2014] [Indexed: 01/26/2023]
Abstract
The brainstem nucleus of the solitary tract (NTS) is the key integrating relay in the central processing of sensory information from the thoracic and from most subdiaphragmatic viscera. Modulation of neuronal excitability and synaptic activity in the NTS by nicotinic agents can have potent effects on vital physiological functions, such as feeding, digestion, respiration, and blood circulation. Caudal NTS neurons demonstrate considerable heterogeneity in projection targets, synaptic properties, and expression of nicotinic acetylcholine receptors (nAChRs). However, despite its heterogeneity, the caudal NTS may contain discrete subsets of neurons with unique projection target-specific properties. To test this hypothesis, we used in vivo fluorescent tracing and ex vivo patch-clamp electrophysiology to evaluate responsiveness to nicotine of anatomically identified caudal NTS neurons that project to the hypothalamic paraventricular nucleus (PVN) and the brainstem caudal ventrolateral medulla (CVLM). The results of this study demonstrate that responsiveness to nicotine correlates with where the neurons project. Specifically, PVN-projecting caudal NTS neurons respond to nicotine only presynaptically (i.e., via activation of presynaptic nAChRs and potentiation of synaptic release of glutamate), suggesting indirect, glutamate-dependent effects of nicotine on the PVN-projecting NTS circuitry. By contrast, CVLM-projecting caudal NTS neurons exhibit only limited presynaptic, but dominant somatodendritic, responsiveness to nicotine, suggesting that the effects of nicotine on the CVLM-projecting NTS circuitry are direct and largely glutamate independent. Understanding the relationships among function-specific brainstem/hypothalamic neuronal networks, nuclei, and individual neurons could help develop therapies targeting identifiable neuronal circuits to offset impaired autonomic homeostasis.
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Affiliation(s)
- Lin Feng
- Department of Pharmacology, Southern Illinois University School of Medicine, Springfield, Illinois
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92
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Grizzell JA, Echeverria V. New Insights into the Mechanisms of Action of Cotinine and its Distinctive Effects from Nicotine. Neurochem Res 2014; 40:2032-46. [PMID: 24970109 DOI: 10.1007/s11064-014-1359-2] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2014] [Accepted: 06/10/2014] [Indexed: 12/20/2022]
Abstract
Tobacco consumption is far higher among a number of psychiatric and neurological diseases, supporting the notion that some component(s) of tobacco may underlie the oft-reported reduction in associated symptoms during tobacco use. Popular dogma holds that this component is nicotine. However, increasing evidence support theories that cotinine, the main metabolite of nicotine, may underlie at least some of nicotine's actions in the nervous system, apart from its adverse cardiovascular and habit forming effects. Though similarities exist, disparate and even antagonizing actions between cotinine and nicotine have been described both in terms of behavior and physiology, underscoring the need to further characterize this potentially therapeutic compound. Cotinine has been shown to be psychoactive in humans and animals, facilitating memory, cognition, executive function, and emotional responding. Furthermore, recent research shows that cotinine acts as an antidepressant and reduces cognitive-impairment associated with disease and stress-induced dysfunction. Despite these promising findings, continued focus on this potentially safe alternative to tobacco and nicotine use is lacking. Here, we review the effects of cotinine, including comparisons with nicotine, and discuss potential mechanisms of cotinine-specific actions in the central nervous system which are, to date, still being elucidated.
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Affiliation(s)
- J Alex Grizzell
- Department of Psychiatry and Behavioral Neurosciences, Morsani College of Medicine, University of South Florida, Tampa, FL, 33611, USA.,Department of Research and Development, Bay Pines VA Healthcare System, 10,000 Bay Pines Blvd., Bldg. 23, Rm. 123, Bay Pines, FL, 33744, USA
| | - Valentina Echeverria
- Department of Research and Development, Bay Pines VA Healthcare System, 10,000 Bay Pines Blvd., Bldg. 23, Rm. 123, Bay Pines, FL, 33744, USA. .,Universidad Autónoma de Chile, Carlos Antúnez 1920, Providencia, Santiago, Chile. .,Department of Molecular Medicine, University of South Florida, Tampa, FL, 33647, USA.
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93
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Marotta C, Rreza I, Lester HA, Dougherty DA. Selective ligand behaviors provide new insights into agonist activation of nicotinic acetylcholine receptors. ACS Chem Biol 2014; 9:1153-9. [PMID: 24564429 PMCID: PMC4033646 DOI: 10.1021/cb400937d] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2013] [Accepted: 02/24/2014] [Indexed: 12/29/2022]
Abstract
Nicotinic acetylcholine receptors are a diverse set of ion channels that are essential to everyday brain function. Contemporary research studies selective activation of individual subtypes of receptors, with the hope of increasing our understanding of behavioral responses and neurodegenerative diseases. Here, we aim to expand current binding models to help explain the specificity seen among three activators of α4β2 receptors: sazetidine-A, cytisine, and NS9283. Through mutational analysis, we can interchange the activation profiles of the stoichiometry-selective compounds sazetidine-A and cytisine. In addition, mutations render NS9283--currently identified as a positive allosteric modulator--into an agonist. These results lead to two conclusions: (1) occupation at each primary face of an α subunit is needed to activate the channel and (2) the complementary face of the adjacent subunit dictates the binding ability of the agonist.
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94
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Tregellas JR, Smucny J, Harris JG, Olincy A, Maharajh K, Kronberg E, Eichman LC, Lyons E, Freedman R. Intrinsic hippocampal activity as a biomarker for cognition and symptoms in schizophrenia. Am J Psychiatry 2014; 171:549-56. [PMID: 24435071 PMCID: PMC4085164 DOI: 10.1176/appi.ajp.2013.13070981] [Citation(s) in RCA: 106] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
OBJECTIVE Identification of biomarkers for cognitive dysfunction in schizophrenia is a priority for psychiatry research. Functional imaging studies suggest that intrinsic "resting state" hippocampal hyperactivity is a characteristic feature of schizophrenia. The relationships between this phenotype and symptoms of the illness, however, are largely unexplored. The authors examined resting hippocampal activity in schizophrenia patients and healthy comparison subjects and analyzed the relationship between intrinsic hippocampal activity and cognitive function in patients as measured by the MATRICS Consensus Cognitive Battery (MCCB). METHOD Twenty-eight schizophrenia patients and 28 age-matched healthy comparison subjects underwent functional "resting state" 3-T MR scanning. Hippocampal activity was extracted by group independent component analysis. Correlation analyses were used to examine the relationship between hippocampal activity and MCCB composite and domain scores in patients, as well as between hippocampal activity and positive and negative symptoms. RESULTS Greater activity of the right hippocampus at rest was observed in patients relative to comparison subjects. In patients, a significant negative correlation was observed between right hippocampal activity and composite MCCB T-score. The correlation was driven by the MCCB domains of attention/vigilance, working memory, and visual learning. Hippocampal activity was positively correlated with negative symptoms. MCCB scores were inversely correlated with negative symptoms. CONCLUSIONS These findings suggest that greater intrinsic hippocampal activity is a characteristic feature of schizophrenia that is broadly associated with cognitive dysfunction, and they support hippocampal activity as a candidate biomarker for therapeutic development.
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95
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Hanin G, Shenhar-Tsarfaty S, Yayon N, Yau YH, Hoe YY, Bennett ER, Sklan EH, Rao DC, Rankinen T, Bouchard C, Geifman-Shochat S, Shifman S, Greenberg DS, Soreq H. Competing targets of microRNA-608 affect anxiety and hypertension. Hum Mol Genet 2014; 23:4569-80. [PMID: 24722204 PMCID: PMC4119407 DOI: 10.1093/hmg/ddu170] [Citation(s) in RCA: 73] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
MicroRNAs (miRNAs) can repress multiple targets, but how a single de-balanced interaction affects others remained unclear. We found that changing a single miRNA-target interaction can simultaneously affect multiple other miRNA-target interactions and modify physiological phenotype. We show that miR-608 targets acetylcholinesterase (AChE) and demonstrate weakened miR-608 interaction with the rs17228616 AChE allele having a single-nucleotide polymorphism (SNP) in the 3'-untranslated region (3'UTR). In cultured cells, this weakened interaction potentiated miR-608-mediated suppression of other targets, including CDC42 and interleukin-6 (IL6). Postmortem human cortices homozygote for the minor rs17228616 allele showed AChE elevation and CDC42/IL6 decreases compared with major allele homozygotes. Additionally, minor allele heterozygote and homozygote subjects showed reduced cortisol and elevated blood pressure, predicting risk of anxiety and hypertension. Parallel suppression of the conserved brain CDC42 activity by intracerebroventricular ML141 injection caused acute anxiety in mice. We demonstrate that SNPs in miRNA-binding regions could cause expanded downstream effects changing important biological pathways.
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Affiliation(s)
- Geula Hanin
- The Silberman Institute of Life Sciences and The Edmond and Lily Safra Center for Brain Sciences, The Hebrew University of Jerusalem, The Edmond Safra Campus, Givat Ram, Jerusalem 91904, Israel
| | - Shani Shenhar-Tsarfaty
- The Silberman Institute of Life Sciences and The Edmond and Lily Safra Center for Brain Sciences, The Hebrew University of Jerusalem, The Edmond Safra Campus, Givat Ram, Jerusalem 91904, Israel
| | - Nadav Yayon
- The Silberman Institute of Life Sciences and The Edmond and Lily Safra Center for Brain Sciences, The Hebrew University of Jerusalem, The Edmond Safra Campus, Givat Ram, Jerusalem 91904, Israel
| | | | - Yau Yin Hoe
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Avenue, 637551, Singapore
| | - Estelle R Bennett
- The Silberman Institute of Life Sciences and The Edmond and Lily Safra Center for Brain Sciences, The Hebrew University of Jerusalem, The Edmond Safra Campus, Givat Ram, Jerusalem 91904, Israel
| | - Ella H Sklan
- Department of Clinical Microbiology and Immunology, Sackler School of Medicine, Tel Aviv University, Tel Aviv 69978, Israel
| | - Dabeeru C Rao
- Division of Biostatistics, School of Medicine, Washington University in St. Louis, St. Louis, MO, USA
| | - Tuomo Rankinen
- Human Genomics Laboratory, Pennington Biomedical Research Center, Baton Rouge, LA, USA
| | - Claude Bouchard
- Human Genomics Laboratory, Pennington Biomedical Research Center, Baton Rouge, LA, USA
| | - Susana Geifman-Shochat
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Avenue, 637551, Singapore
| | | | - David S Greenberg
- The Silberman Institute of Life Sciences and The Edmond and Lily Safra Center for Brain Sciences, The Hebrew University of Jerusalem, The Edmond Safra Campus, Givat Ram, Jerusalem 91904, Israel
| | - Hermona Soreq
- The Silberman Institute of Life Sciences and The Edmond and Lily Safra Center for Brain Sciences, The Hebrew University of Jerusalem, The Edmond Safra Campus, Givat Ram, Jerusalem 91904, Israel
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96
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Targowska-Duda KM, Feuerbach D, Biala G, Jozwiak K, Arias HR. Antidepressant activity in mice elicited by 3-furan-2-yl-N-p-tolyl-acrylamide, a positive allosteric modulator of the α7 nicotinic acetylcholine receptor. Neurosci Lett 2014; 569:126-30. [PMID: 24708923 DOI: 10.1016/j.neulet.2014.03.067] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2013] [Revised: 03/19/2014] [Accepted: 03/27/2014] [Indexed: 01/05/2023]
Abstract
The objective of the current study is to determine whether 3-furan-2-yl-N-p-tolyl-acrylamide (PAM-2), a positive allosteric modulator of α7 nicotinic receptors (AChRs), produces antidepressant-like behavior in mice, and reactivates desensitized α7 AChRs expressed in CH3-α7 cells. Mice from both sexes were injected (i.p.) with PAM-2 (1.0mg/kg) on a daily basis for three weeks. Forced swim tests (FSTs) were performed on Day 1 and Day 7 to determine the acute and subchronic effects of PAM-2, respectively, and on Days 14 and 21 to determine its chronic activity. To examine the residual effects after drug treatment, a withdrawal period of two more weeks was continued with FSTs performed on Day 28 and 35. Our results indicate that: (1) PAM-2 does not induce acute antidepressant effects in male or female mice, (2) PAM-2 induces antidepressant effects in mice from both sexes after one (subchronic) and two (chronic) weeks, whereas at the third week (chronic), the antidepressant effect is decreased in male and increased in female mice. Since PAM-2 does not influence the locomotor activity of mice, the observed antidepressant activity is not driven by nonspecific motor-stimulant actions, (3) the residual antidepressant effect mediated by PAM-2 after one week of treatment cessation is observed only in female mice, and finally the Ca(2+) influx results indicate that (4) PAM-2 can reactivate desensitized α7 AChRs. Our results clearly indicate that PAM-2 elicits antidepressant activity, probably by enhancing the activity of the endogenous neurotransmitter acetylcholine on α7 AChRs, without inducing receptor desensitization, and that this activity is gender-dependent. This is the first time that an antidepressant activity is described for an α7 PAM, supporting further studies as potential therapeutic medications for depressive states.
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Affiliation(s)
- Katarzyna M Targowska-Duda
- Department of Chemistry, Laboratory of Medicinal Chemistry and Neuroengineering, Medical University of Lublin, 4a Chodzki Street, 20-093 Lublin, Poland.
| | | | - Grazyna Biala
- Department of Pharmacology and Pharmacodynamics, Medical University of Lublin, 4a Chodzki Street, 20-093 Lublin, Poland
| | - Krzysztof Jozwiak
- Department of Chemistry, Laboratory of Medicinal Chemistry and Neuroengineering, Medical University of Lublin, 4a Chodzki Street, 20-093 Lublin, Poland
| | - Hugo R Arias
- Department of Medical Education, California Northstate University College of Medicine, 9700 West Taron Drive, Elk Grove, CA 95757, USA.
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97
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Scott H, Panin VM. The role of protein N-glycosylation in neural transmission. Glycobiology 2014; 24:407-17. [PMID: 24643084 DOI: 10.1093/glycob/cwu015] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Recent studies have explored the function of N-linked glycosylation in the nervous system, demonstrating essential roles of carbohydrate structures in neural development. The function of N-glycans in neural physiology remains less understood; however, increasing evidence indicates that N-glycans can play specific modulatory roles controlling neural transmission and excitability of neural circuits. These roles are mediated via effects on synaptic proteins involved in neurotransmitter release, transporters that regulate nerotransmitter concentrations, neurotransmitter receptors, as well as via regulation of proteins that control excitability and response to milieu stimuli, such as voltage-gated ion channels and transient receptor potential channels, respectively. Sialylated N-glycan structures are among the most potent modulators of cell excitability, exerting prominent effects on voltage gated Na(+) and K(+) channels. This modulation appears to be underlain by complex molecular mechanisms involving electrostatic effects, as well as interaction modes based on more specific steric effects and interactions with lectins and other molecules. Data also indicate that particular features of N-glycans, such as their location on a protein and structural characteristics, can be specifically associated with the effect of glycosylation. These features and their functional implications can vary between different cell types, which highlight the importance of in vivo analyses of glycan functions. Experimental challenges are associated with the overwhelming complexity of the nervous system and glycosylation pathways in vertebrates, and thus model organisms like Drosophila should help elucidate evolutionarily conserved mechanisms underlying glycan functions. Recent studies supported this notion and shed light on functions of several glycosylation genes involved in the regulation of the nervous system.
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Affiliation(s)
- Hilary Scott
- Department of Biochemistry and Biophysics, Texas A&M University, 2128 TAMU, College Station, TX 77843, USA
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98
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Srinivasan R, Henderson BJ, Lester HA, Richards CI. Pharmacological chaperoning of nAChRs: a therapeutic target for Parkinson's disease. Pharmacol Res 2014; 83:20-9. [PMID: 24593907 DOI: 10.1016/j.phrs.2014.02.005] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/31/2013] [Revised: 02/18/2014] [Accepted: 02/18/2014] [Indexed: 01/03/2023]
Abstract
Chronic exposure to nicotine results in an upregulation of neuronal nicotinic acetylcholine receptors (nAChRs) at the cellular plasma membrane. nAChR upregulation occurs via nicotine-mediated pharmacological receptor chaperoning and is thought to contribute to the addictive properties of tobacco as well as relapse following smoking cessation. At the subcellular level, pharmacological chaperoning by nicotine and nicotinic ligands causes profound changes in the structure and function of the endoplasmic reticulum (ER), ER exit sites, the Golgi apparatus and secretory vesicles of cells. Chaperoning-induced changes in cell physiology exert an overall inhibitory effect on the ER stress/unfolded protein response. Cell autonomous factors such as the repertoire of nAChR subtypes expressed by neurons and the pharmacological properties of nicotinic ligands (full or partial agonist versus competitive antagonist) govern the efficiency of receptor chaperoning and upregulation. Together, these findings are beginning to pave the way for developing pharmacological chaperones to treat Parkinson's disease and nicotine addiction.
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Affiliation(s)
- Rahul Srinivasan
- Department of Physiology, University of California Los Angeles, Los Angeles, CA, United States.
| | - Brandon J Henderson
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, United States
| | - Henry A Lester
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, United States
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99
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Howard RJ, Trudell JR, Harris RA. Seeking structural specificity: direct modulation of pentameric ligand-gated ion channels by alcohols and general anesthetics. Pharmacol Rev 2014; 66:396-412. [PMID: 24515646 PMCID: PMC3973611 DOI: 10.1124/pr.113.007468] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Alcohols and other anesthetic agents dramatically alter neurologic function in a wide range of organisms, yet their molecular sites of action remain poorly characterized. Pentameric ligand-gated ion channels, long implicated in important direct effects of alcohol and anesthetic binding, have recently been illuminated in renewed detail thanks to the determination of atomic-resolution structures of several family members from lower organisms. These structures provide valuable models for understanding and developing anesthetic agents and for allosteric modulation in general. This review surveys progress in this field from function to structure and back again, outlining early evidence for relevant modulation of pentameric ligand-gated ion channels and the development of early structural models for ion channel function and modulation. We highlight insights and challenges provided by recent crystal structures and resulting simulations, as well as opportunities for translation of these newly detailed models back to behavior and therapy.
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Affiliation(s)
- Rebecca J Howard
- Department of Chemistry, Skidmore College, Saratoga Springs, NY 12866.
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100
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Shi M, Yue Z, Kuryatov A, Lindstrom JM, Sehgal A. Identification of Redeye, a new sleep-regulating protein whose expression is modulated by sleep amount. eLife 2014; 3:e01473. [PMID: 24497543 PMCID: PMC3912633 DOI: 10.7554/elife.01473] [Citation(s) in RCA: 73] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
In this study, we report a new protein involved in the homeostatic regulation of sleep in Drosophila. We conducted a forward genetic screen of chemically mutagenized flies to identify short-sleeping mutants and found one, redeye (rye) that shows a severe reduction of sleep length. Cloning of rye reveals that it encodes a nicotinic acetylcholine receptor α subunit required for Drosophila sleep. Levels of RYE oscillate in light-dark cycles and peak at times of daily sleep. Cycling of RYE is independent of a functional circadian clock, but rather depends upon the sleep homeostat, as protein levels are up-regulated in short-sleeping mutants and also in wild type animals following sleep deprivation. We propose that the homeostatic drive to sleep increases levels of RYE, which responds to this drive by promoting sleep. DOI: http://dx.doi.org/10.7554/eLife.01473.001.
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Affiliation(s)
- Mi Shi
- Howard Hughes Medical Institute, University of Pennsylvania, Philadelphia, United States
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