1
|
Samra GK, Intskirveli I, Govind AP, Liang C, Lazar R, Green WN, Metherate R, Mukherjee J. Development of fluorescence imaging probes for nicotinic acetylcholine α4β2 ∗ receptors. Bioorg Med Chem Lett 2018; 28:371-377. [PMID: 29277457 DOI: 10.1016/j.bmcl.2017.12.036] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2017] [Revised: 12/13/2017] [Accepted: 12/16/2017] [Indexed: 11/29/2022]
Abstract
Nicotinic acetylcholine α4β2∗ receptors (nAChRs) are implicated in various neurodegenerative diseases and smoking addiction. Imaging of brain high-affinity α4β2∗ nAChRs at the cellular and subcellular levels would greatly enhance our understanding of their functional role. Since better resolution could be achieved with fluorescent probes, using our previously developed positron emission tomography (PET) imaging agent [18F]nifrolidine, we report here design, synthesis and evaluation of two fluorescent probes, nifrodansyl and nifrofam for imaging α4β2∗ nAChRs. The nifrodansyl and nifrofam exhibited nanomolar affinities for the α4β2∗ nAChRs in [3H]cytisine-radiolabeled rat brain slices. Nifrofam labeling was observed in α4β2∗ nAChR-expressing HEK cells and was upregulated by nicotine exposure. Nifrofam co-labeled cell-surface α4β2∗ nAChRs, labeled with antibodies specific for a β2 subunit extracellular epitope indicating that nifrofam labels α4β2∗ nAChR high-affinity binding sites. Mouse brain slices exhibited discrete binding of nifrofam in the auditory cortex showing promise for examining cellular distribution of α4β2∗ nAChRs in brain regions.
Collapse
Affiliation(s)
- Gurleen K Samra
- Preclinical Imaging, Department of Radiological Sciences, University of California-Irvine, Irvine, CA 92697, United States
| | - Irakli Intskirveli
- Department of Neurobiology and Behavior, University of California-Irvine, Irvine, CA 92697, United States
| | - Anitha P Govind
- Department of Neurobiology, University of Chicago, IL 60637, United States
| | - Christopher Liang
- Preclinical Imaging, Department of Radiological Sciences, University of California-Irvine, Irvine, CA 92697, United States
| | - Ronit Lazar
- Department of Neurobiology and Behavior, University of California-Irvine, Irvine, CA 92697, United States
| | - William N Green
- Department of Neurobiology, University of Chicago, IL 60637, United States
| | - Raju Metherate
- Department of Neurobiology and Behavior, University of California-Irvine, Irvine, CA 92697, United States
| | - Jogeshwar Mukherjee
- Preclinical Imaging, Department of Radiological Sciences, University of California-Irvine, Irvine, CA 92697, United States; Department of Biomedical Engineering, University of California-Irvine, Irvine, CA 92697, United States.
| |
Collapse
|
2
|
Suarez SV, Amadon A, Giacomini E, Wiklund A, Changeux JP, Le Bihan D, Granon S. Brain activation by short-term nicotine exposure in anesthetized wild-type and beta2-nicotinic receptors knockout mice: a BOLD fMRI study. Psychopharmacology (Berl) 2009; 202:599-610. [PMID: 18818904 DOI: 10.1007/s00213-008-1338-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/14/2008] [Accepted: 09/10/2008] [Indexed: 01/08/2023]
Abstract
RATIONALE The behavioral effects of nicotine and the role of the beta2-containing nicotinic receptors in these behaviors are well documented. However, the behaviors altered by nicotine rely on the functioning on multiple brain circuits where the high-affinity beta2-containing nicotinic receptors (beta2*nAChRs) are located. OBJECTIVES We intend to see which brain circuits are activated when nicotine is given in animals naïve for nicotine and whether the beta2*nAChRs are needed for its activation of the blood oxygen level dependent (BOLD) signal in all brain areas. MATERIALS AND METHODS We used functional magnetic resonance imaging (fMRI) to measure the brain activation evoked by nicotine (1 mg/kg delivered at a slow rate for 45 min) in anesthetized C57BL/6J mice and beta2 knockout (KO) mice. RESULTS Acute nicotine injection results in a significant increased activation in anterior frontal, motor, and somatosensory cortices and in the ventral tegmental area and the substantia nigra. Anesthetized mice receiving no nicotine injection exhibited a major decreased activation in all cortical and subcortical structures, likely due to prolonged anesthesia. At a global level, beta2 KO mice were not rescued from the globally declining BOLD signal. However, nicotine still activated regions of a meso-cortico-limbic circuit likely via alpha7 nicotinic receptors. CONCLUSIONS Acute nicotine exposure compensates for the drop in brain activation due to anesthesia through the meso-cortico-limbic network via the action of nicotine on beta2*nAChRs. The developed fMRI method is suitable for comparing responses in wild-type and mutant mice.
Collapse
Affiliation(s)
- S V Suarez
- Unité de Neurobiologie Intégrative du Système Cholinergique, URA CNRS 2182, Institut Pasteur, Département de Neuroscience, 25 rue du Dr. Roux, 75015 Paris, France
| | | | | | | | | | | | | |
Collapse
|
3
|
Gotti C, Clementi F. Neuronal nicotinic receptors: from structure to pathology. Prog Neurobiol 2005; 74:363-96. [PMID: 15649582 DOI: 10.1016/j.pneurobio.2004.09.006] [Citation(s) in RCA: 707] [Impact Index Per Article: 37.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2004] [Accepted: 09/29/2004] [Indexed: 02/07/2023]
Abstract
Neuronal nicotinic receptors (NAChRs) form a heterogeneous family of ion channels that are differently expressed in many regions of the central nervous system (CNS) and peripheral nervous system. These different receptor subtypes, which have characteristic pharmacological and biophysical properties, have a pentameric structure consisting of the homomeric or heteromeric combination of 12 different subunits (alpha2-alpha10, beta2-beta4). By responding to the endogenous neurotransmitter acetylcholine, NAChRs contribute to a wide range of brain activities and influence a number of physiological functions. Furthermore, it is becoming evident that the perturbation of cholinergic nicotinic neurotransmission can lead to various diseases involving nAChR dysfunction during development, adulthood and ageing. In recent years, it has been discovered that NAChRs are present in a number of non-neuronal cells where they play a significant functional role and are the pathogenetic targets in several diseases. NAChRs are also the target of natural ligands and toxins including nicotine (Nic), the most widespread drug of abuse. This review will attempt to survey the major achievements reached in the study of the structure and function of NAChRs by examining their regional and cellular localisation and the molecular basis of their functional diversity mainly in pharmacological and biochemical terms. The recent availability of mice with the genetic ablation of single or double nicotinic subunits or point mutations have shed light on the role of nAChRs in major physiological functions, and we will here discuss recent data relating to their behavioural phenotypes. Finally, the role of NAChRs in disease will be considered in some details.
Collapse
Affiliation(s)
- C Gotti
- CNR, Institute of Neuroscience, Cellular and Molecular Pharmacology Section, Department of Medical Pharmacology and Center of Excellence on Neurodegenerative Diseases, University of Milan, Via Vanvitelli 32, 20129 Milan, Italy
| | | |
Collapse
|
4
|
Fischer H, Orr-Urtreger A, Role LW, Huck S. Selective deletion of the alpha5 subunit differentially affects somatic-dendritic versus axonally targeted nicotinic ACh receptors in mouse. J Physiol 2004; 563:119-37. [PMID: 15611037 PMCID: PMC1665561 DOI: 10.1113/jphysiol.2004.075788] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
We have compared the functional properties of nicotinic acetylcholine receptors (nAChRs) within both somatic and presynaptic domains of superior cervical ganglion (SCG) neurones from wild-type (WT) mice with those expressed by SCG neurones from mice with a targeted deletion of the gene for the alpha5-subunit. The functional profile of somatic nAChRs was assayed by direct macroscopic current recording and from measurements of nicotinic agonist-induced calcium transients with fura-2 imaging. The profile of nAChRs at presynaptic sites was assayed by measurement of nicotinic agonist-induced transmitter release (as preloaded [3H]noradrenaline) under conditions of action potential blockade. We have examined the responses to the nicotinic agonists acetylcholine, nicotine, cytisine, dimethylphenylpiperazinium iodide (DMPP) and epibatidine. Macroscopic current and calcium imaging assays revealed several differences in the functional profile of somatic nAChRs in WT SCG neurones compared with those from mice with the alpha5 subunit deleted. Somatic nAChRs in control animals were more potently activated by cytisine as compared to DMPP. In contrast, DMPP was consistently more potent than cytisine in mice lacking the alpha5 nAChR subunit. Differences in the somatic nAChR rank order of potency were most prominent after a least 1 day in vitro. The magnitude of somatic nAChR responses to nicotinic agonists was not substantially different in control mice compared with those of alpha5 subunit-deleted animals. Comparison of presynaptic nAChR-mediated responses in WT versus alpha5 subunit-deleted animals revealed a very different set of changes in the functional profile of prejunctional nAChRs compared with somatic nAChRs. In contrast to somatic nAChRs, the responses of prejunctional receptors were markedly enhanced in alpha5 knockout animals compared with control. Furthermore, all prejunctional receptor responses were most potently activated by DMPP in both control and in alpha5 subunit-deleted mice. Hence, the presence or absence of the alpha5 subunit did not affect the rank order of potency of agonists at preterminal sites but greatly affected the magnitude of presynaptic nAChR-mediated responses. The enhanced efficacy of nicotine at presynaptic receptors was corroborated in an acute atrium preparation from postnatal alpha5 subunit-deleted mice. These results confirm and significantly extend our previous observation that in the sympathetic nervous system, somatic and prejunctional receptors are different and rely on the presence of the alpha5 subunit in a distinct manner.
Collapse
Affiliation(s)
- Harald Fischer
- Division of Biochemistry and Molecular Biology, Centre for Brain Research, Medical University Vienna, Spitalgasse 4, A-1090 Vienna, Austria
| | | | | | | |
Collapse
|
5
|
de Freitas RL, de Oliveira RC, de Carvalho AD, Felippotti TT, Bassi GS, Elias-Filho DH, Coimbra NC. Role of muscarinic and nicotinic cholinergic receptors in an experimental model of epilepsy-induced analgesia. Pharmacol Biochem Behav 2004; 79:367-76. [PMID: 15501314 DOI: 10.1016/j.pbb.2004.08.007] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/07/2004] [Revised: 08/15/2004] [Accepted: 08/16/2004] [Indexed: 01/11/2023]
Abstract
The blockade of GABA-mediated Cl(-) influx with pentylenetetrazol (PTZ) was used in the present work to induce seizures in animals. The neurotransmission in the postictal period has been the focus of many studies, and there is evidence suggesting antinociceptive mechanisms following tonic-clonic seizures in both animals and men. The aim of this work was to study the involvement of acetylcholine in the antinociception induced by convulsions elicited by peripheral administration of PTZ (64 mg/kg). Analgesia was measured by the tail-flick test in eight albino Wistar rats per group. Convulsions were followed by significant increases in tail-flick latencies (TFLs) at least for 120 min of the postictal period. Peripheral administration of atropine (0.25, 1 and 4 mg/kg) caused a significant dose-dependent decrease in the TFL in seizing animals, as compared to controls. These data were corroborated by peripheral administration of mecamylamine, a nicotinic cholinergic receptor blocker, at the same doses (0.25, 1 and 4 mg/kg) used for the muscarinic cholinergic receptor antagonist. The recruitment of the muscarinic receptor was made 10 min postconvulsions and in subsequent periods of postictal analgesia, whereas the involvement of the nicotinic cholinergic receptor was implicated only after 30 min postseizures. The cholinergic antagonists caused a minimal reduction in body temperature, but did not impair baseline TFL, spontaneous exploration or motor coordination in the rotarod test at the maximal dose of 4 mg/kg. These results indicate that acetylcholine may be involved as a neurotransmitter in postictal analgesia.
Collapse
Affiliation(s)
- Renato Leonardo de Freitas
- Laboratório de Neuroanatomia e Neuropsicobiologia, Departamento de Farmacologia, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo (USP), 14049-900, Avenida dos Bandeirantes, 3900, Ribeirão Preto (SP), Brazil
| | | | | | | | | | | | | |
Collapse
|
6
|
Martin LF, Kem WR, Freedman R. Alpha-7 nicotinic receptor agonists: potential new candidates for the treatment of schizophrenia. Psychopharmacology (Berl) 2004; 174:54-64. [PMID: 15205879 DOI: 10.1007/s00213-003-1750-1] [Citation(s) in RCA: 266] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/29/2003] [Accepted: 11/28/2003] [Indexed: 01/16/2023]
Abstract
RATIONALE AND OBJECTIVE Auditory sensory gating, a biological measurement of the ability to suppress the evoked response to the second of two auditory stimuli, is diminished in people with schizophrenia. Deficits in sensory gating are associated with attentional impairment, and may contribute to cognitive symptoms and perceptual disturbances. This inhibitory process, which involves the alpha(7) nicotinic receptor mediated release of gamma-aminobutyric acid (GABA) by hippocampal interneurons, represents a potential new target for therapeutic intervention in schizophrenia. METHOD This paper will review several lines of evidence implicating the nicotinic-cholinergic, and specifically, the alpha(7) nicotinic receptor system in the pathology of schizophrenia and the evidence that alpha(7) nicotinic receptor agonists may ameliorate some of these deficits. RESULTS Impaired auditory sensory gating has been linked to the alpha(7) nicotinic receptor gene on the chromosome 15q14 locus. Single nucleotide polymorphisms of the promoter region of this gene are more frequent in people with schizophrenia. Although nicotine can acutely reverse diminished auditory sensory gating in people with schizophrenia, this effect is lost on a chronic basis due to receptor desensitization. Clozapine is able to reverse auditory sensory gating impairment, probably through an alpha(7) nicotinic receptor mechanism, in both humans and animal models with repeated dosing. The alpha(7) nicotinic agonist 3-2,4 dimethoxybenzylidene anabaseine (DMXBA) can also enhance auditory sensory gating in animal models. DMXBA is well tolerated in humans and improves several cognitive measures. CONCLUSION Alpha-7 nicotinic receptor agonists appear to be reasonable candidates for the treatment of cognitive and perceptual disturbances in schizophrenia.
Collapse
Affiliation(s)
- Laura F Martin
- Department of Psychiatry, Department of Veterans Affairs and University of Colorado Health Sciences Center, 4200 East Ninth Avenue, C268-71, Denver, CO 80262, USA.
| | | | | |
Collapse
|
7
|
Neuroprotection by nicotine in mouse primary cortical cultures involves activation of calcineurin and L-type calcium channel inactivation. J Neurosci 2003. [PMID: 14602824 DOI: 10.1523/jneurosci.23-31-10093.2003] [Citation(s) in RCA: 90] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Regulation of intracellular calcium influences neuronal excitability, synaptic plasticity, gene expression, and neurotoxicity. In this study, we investigated the role of calcium in mechanisms underlying nicotine-mediated neuroprotection from glutamate excitotoxicity. Neuroprotection by nicotine in primary cortical cultures was not seen in knock-out mice lacking the beta2 subunit of the nicotinic acetylcholine receptor (nAChR). Neuroprotection was partially blocked in wild-type cultures by alpha-bungarotoxin, an antagonist of the alpha7 nAChR subtype, suggesting a potential cooperative role for these subtypes. Pretreatment with nicotine decreased glutamate-mediated calcium influx in primary cortical cultures by 41%, an effect that was absent in cultures from knock-out mice lacking the beta2 subunit of the nAChR. This effect was dependent on calcium entry through L-type channels during nicotine pretreatment in wild-type cultures. The ability of nicotine to decrease glutamate-mediated calcium influx was occluded by cotreatment with nifedipine during glutamate application, suggesting that nicotine pretreatment decreased subsequent activity of L-type calcium channels. Treatment with the calcineurin antagonists FK506 and cyclosporine during pretreatment eliminated both nicotine-mediated neuroprotection and the effects of nicotine on L-type channels. We conclude that neuroprotective effects of nicotine in cortical neurons involve both beta2- and alpha7-containing nAChRs, activation of calcineurin, and decreased intracellular calcium via L-type channels.
Collapse
|