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Rahimian R, Dehpour AR, Fakhfouri G, Khorramizadeh MR, Ghia JE, Seyedabadi M, Caldarelli A, Mousavizadeh K, Forouzandeh M, Mehr SE. Tropisetron upregulates cannabinoid CB1 receptors in cerebellar granule cells: Possible involvement of calcineurin. Brain Res 2011; 1417:1-8. [DOI: 10.1016/j.brainres.2011.08.050] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2011] [Revised: 08/18/2011] [Accepted: 08/19/2011] [Indexed: 01/17/2023]
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152
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Ali SA, Salim S, Sahni T, Peter J, Ali AS. 5-HT receptors as novel targets for optimizing pigmentary responses in dorsal skin melanophores of frog, Hoplobatrachus tigerinus. Br J Pharmacol 2011; 165:1515-25. [PMID: 21880033 DOI: 10.1111/j.1476-5381.2011.01630.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
BACKGROUND AND PURPOSE Biochemical identification of 5-HT has revealed similar projection patterns across vertebrates. In CNS, 5-HT regulates major physiological functions but its peripheral functions are still emerging. The pharmacology of 5-HT is mediated by a diverse range of receptors that trigger different responses. Interestingly, 5-HT receptors have been detected in pigment cells indicating their role in skin pigmentation. Hence, we investigated the role of this monoaminergic system in amphibian pigment cells, melanophores, to further our understanding of its role in pigmentation biology together with its evolutionary significance. EXPERIMENTAL APPROACH Pharmacological profiling of 5-HT receptors was achieved using potent/selective agonists and antagonists. In vitro responses of melanophores were examined by Mean Melanophores Size Index assay. The melanophores of lower vertebrates are highly sensitive to external stimuli. The immediate cellular responses to drugs were defined in terms of pigment translocation within the cells. KEY RESULTS 5-HT exerted strong concentration-dependent pigment dispersion at threshold dose of 1 × 10(-6) g·mL(-1). Specific 5-HT(1) and 5-HT(2) receptor agonists, sumatriptan and myristicin. also induced dose-dependent dispersion. Yohimbine and metergoline synergistically antagonized sumatriptan-mediated dispersion, whereas trazodone partially blocked myristicin-induced dispersion. Conversely, 5-HT(3) and 5-HT(4) receptor agonists, 1 (3 chlorophenyl) biguanide (1,3 CPB) and 5-methoxytryptamine (5-MT), caused a dose-dependent pigment aggregation. The aggregatory effect of 1,3 CPB was completely blocked by ondansetron, whereas L-lysine partially blocked the effect of 5-MT. CONCLUSIONS AND IMPLICATIONS The results suggest that 5-HT-induced physiological effects are mediated via distinct classes of receptors, which possibly participate in the modulation of pigmentary responses in amphibian.
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Affiliation(s)
- Sharique A Ali
- Department of Biotechnology, Saifia College of Science, Bhopal, India.
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153
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Liu S, Babcock MS, Bode J, Chang JS, Fischer HD, Garlick RL, Gill GS, Lund ET, Margolis BJ, Mathews WR, Rogers BN, Wolfe M, Groppi V, Baldwin ET. Affinity purification of a chimeric nicotinic acetylcholine receptor in the agonist and antagonist bound states. Protein Expr Purif 2011; 79:102-10. [DOI: 10.1016/j.pep.2011.05.019] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2011] [Revised: 05/19/2011] [Accepted: 05/26/2011] [Indexed: 10/18/2022]
Affiliation(s)
- Shenping Liu
- Pfizer Inc., Pfizer Global Research and Development, Groton, CT 06340, United States.
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154
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Oostland M, Sellmeijer J, van Hooft JA. Transient expression of functional serotonin 5-HT3 receptors by glutamatergic granule cells in the early postnatal mouse cerebellum. J Physiol 2011; 589:4837-46. [PMID: 21878518 DOI: 10.1113/jphysiol.2011.217307] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The serotonin 5-HT(3) receptor is the only ligand-gated ion channel activated by serotonin and is expressed by GABAergic interneurons in many brain regions, including the cortex, amygdala and hippocampus. Furthermore, 5-HT(3) receptors are expressed by glutamatergic Cajal-Retzius cells in the cerebral cortex. We used 5-HT(3A)/enhanced green fluorescent protein (EGFP) transgenic mice to show that 5-HT(3) receptors are also ubiquitously expressed by glutamatergic granule cells in the cerebellum during the first three postnatal weeks. Using whole-cell patch clamp recordings, we show that local application of either serotonin or the selective 5-HT(3) receptor agonist SR57227A to granule cells results in a small inward current, demonstrating a post- and/or extrasynaptic localisation of the 5-HT(3) receptors. Functional 5-HT(3) receptors were also observed presynaptically at the parallel fibre-Purkinje cell synapse. Pharmacological block using the selective 5-HT(3) receptor antagonist tropisetron induced a reduction in the frequency of miniature synaptic events recorded from Purkinje cells. Paired-pulse stimulation of parallel fibres on whole-cell voltage clamped Purkinje cells from 1-week-old mice did not yet show synaptic plasticity. In the presence of tropisetron, the parallel fibre-Purkinje cell synapse showed paired-pulse depression. Taken together, these results show that functional 5-HT(3) receptors are present during early postnatal development in the cerebellum, where they modulate synaptic plasticity.
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Affiliation(s)
- Marlies Oostland
- Swammerdam Institute for Life Sciences, Center for Neuroscience, University of Amsterdam, Amsterdam, The Netherlands
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155
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Huot P, Fox SH, Brotchie JM. The serotonergic system in Parkinson's disease. Prog Neurobiol 2011; 95:163-212. [PMID: 21878363 DOI: 10.1016/j.pneurobio.2011.08.004] [Citation(s) in RCA: 135] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2011] [Revised: 08/05/2011] [Accepted: 08/15/2011] [Indexed: 01/23/2023]
Abstract
Although the cardinal manifestations of Parkinson's disease (PD) are attributed to a decline in dopamine levels in the striatum, a breadth of non-motor features and treatment-related complications in which the serotonergic system plays a pivotal role are increasingly recognised. Serotonin (5-HT)-mediated neurotransmission is altered in PD and the roles of the different 5-HT receptor subtypes in disease manifestations have been investigated. The aims of this article are to summarise and discuss all published preclinical and clinical studies that have investigated the serotonergic system in PD and related animal models, in order to recapitulate the state of the current knowledge and to identify areas that need further research and understanding.
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Affiliation(s)
- Philippe Huot
- Toronto Western Research Institute, MCL 11-419, Toronto Western Hospital, University Health Network, 399 Bathurst Street, Toronto, Ontario, Canada M5T 2S8
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156
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Inta D, Vogt MA, Lima-Ojeda JM, Pfeiffer N, Schneider M, Gass P. Lack of long-term behavioral alterations after early postnatal treatment with tropisetron: Implications for developmental psychobiology. Pharmacol Biochem Behav 2011; 99:35-41. [DOI: 10.1016/j.pbb.2011.03.020] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/18/2010] [Revised: 03/17/2011] [Accepted: 03/25/2011] [Indexed: 12/24/2022]
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157
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Dubinsky L, Krom BP, Meijler MM. Diazirine based photoaffinity labeling. Bioorg Med Chem 2011; 20:554-70. [PMID: 21778062 DOI: 10.1016/j.bmc.2011.06.066] [Citation(s) in RCA: 283] [Impact Index Per Article: 21.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2011] [Revised: 06/19/2011] [Accepted: 06/24/2011] [Indexed: 10/17/2022]
Abstract
Diazirines are among the smallest photoreactive groups that form a reactive carbene upon light irradiation. This feature has been widely utilized in photoaffinity labeling to study ligand-receptor, ligand-enzyme and protein-protein interactions, and in the isolation and identification of unknown proteins. This review summarizes recent advances in the use of diazirines in photoaffinity labeling.
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Affiliation(s)
- Luba Dubinsky
- Department of Chemistry and National Institute for Biotechnology in the Negev, Ben-Gurion University of the Negev, Be'er Sheva, Israel
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158
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Machu TK. Therapeutics of 5-HT3 receptor antagonists: current uses and future directions. Pharmacol Ther 2011; 130:338-47. [PMID: 21356241 PMCID: PMC3103470 DOI: 10.1016/j.pharmthera.2011.02.003] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2011] [Accepted: 02/09/2011] [Indexed: 12/14/2022]
Abstract
The 5-Hydroxytryptamine3 (5-HT3) receptor is a member of the cys-loop family of ligand gated ion channels, of which the nicotinic acetylcholine receptor is the prototype. All other 5-HT receptors identified to date are metabotropic receptors. The 5-HT3 receptor is present in the central and peripheral nervous systems, as well as a number of non-nervous tissues. As an ion channel that is permeable to the cations, Na(+), K(+), and Ca(2+), the 5-HT3 receptor mediates fast depolarizing responses in pre- and post-synaptic neurons. As such, 5-HT3 receptor antagonists that are used clinically block afferent and efferent synaptic transmission. The most well established physiological roles of the 5-HT3 receptor are to coordinate emesis and regulate gastrointestinal motility. Currently marketed 5-HT3 receptor antagonists are indicated for the treatment of chemotherapy, radiation, and anesthesia-induced nausea and vomiting, as well as irritable bowel syndrome. Other therapeutic uses that have been explored include pain and drug addiction. The 5-HT3 receptor is one of a number of receptors that play a role in mediating nausea and vomiting, and as such, 5-HT3 receptor antagonists demonstrate the greatest anti-emetic efficacy when administered in combination with other drug classes.
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Affiliation(s)
- Tina K Machu
- Dept. of Medical Education and Dept. of Pharmacology and Neuroscience, University of North Texas Health Science Center, 3500 Camp Bowie Blvd. Fort Worth, TX 76107-2699, USA.
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159
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Kilpatrick LA, Labus JS, Coveleskie K, Hammer C, Rappold G, Tillisch K, Bueller JA, Suyenobu B, Jarcho JM, McRoberts JA, Niesler B, Mayer EA. The HTR3A polymorphism c. -42C>T is associated with amygdala responsiveness in patients with irritable bowel syndrome. Gastroenterology 2011; 140:1943-51. [PMID: 21420406 PMCID: PMC3757951 DOI: 10.1053/j.gastro.2011.03.011] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/10/2010] [Revised: 02/02/2011] [Accepted: 03/07/2011] [Indexed: 12/19/2022]
Abstract
BACKGROUND & AIMS 5-Hydroxytryptamine (5-HT)3 receptor (5-HT3R) antagonists are effective in treating patients with irritable bowel syndrome (IBS) and have anxiolytic effects. Their therapeutic effects are related, in part, to reducing amygdala engagement during expected visceral pain. A single nucleotide polymorphism in HTR3A, c.-42C>T;(C178T; rs1062613), is associated with altered reactivity of the amygdala during emotional face processing in healthy subjects (controls). We evaluated the influence of this single nucleotide polymorphism on amygdala reactivity to emotional faces and nonemotional stimuli in female patients with IBS and controls. METHODS We measured brain responses during an affect-matching paradigm in 54 women (26 with IBS, 29 controls) using functional magnetic resonance imaging. We examined associations between HTR3A c.-42C>T genotype (C/C vs T carrier) and responses in amygdala and other regions of brain that expressed high levels of 5-HT3R. RESULTS The C/C genotype was associated with greater anxiety symptoms in patients with IBS and controls and increased activation of the amygdala under emotional and nonemotional conditions. Among patients with IBS, C/C genotype was associated with greater symptom ratings. A subset of IBS patients with the C/C genotype had increased amygdala responses to nonemotional stimuli, compared with other subjects with C/C genotype. CONCLUSIONS Regardless of diagnosis, the C/C genotype of the c.-42C>T polymorphism in HTR3A, compared with T carrier status, is associated with increased anxiety and amygdala responsiveness during emotional and nonemotional tasks. This polymorphism was associated with severity of IBS symptoms. Although this genotype is not sufficient for diagnosis of IBS, it is associated with severity of symptoms.
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Affiliation(s)
- LA Kilpatrick
- Center for Neurobiology of Stress, Ahmanson-Lovelace Brain Mapping Center, UCLA, Department of Medicine, Ahmanson-Lovelace Brain Mapping Center, UCLA
| | - JS Labus
- Center for Neurobiology of Stress, Ahmanson-Lovelace Brain Mapping Center, UCLA, Department of Psychiatry & Biobehavioral Sciences, Ahmanson-Lovelace Brain Mapping Center, UCLA, Brain Research Institute, David Geffen School of Medicine, UCLA
| | - K Coveleskie
- Center for Neurobiology of Stress, Ahmanson-Lovelace Brain Mapping Center, UCLA
| | - C Hammer
- Department of Human Molecular Genetics, University of Heidelberg, Germany
| | - G Rappold
- Department of Human Molecular Genetics, University of Heidelberg, Germany
| | - K Tillisch
- Center for Neurobiology of Stress, Ahmanson-Lovelace Brain Mapping Center, UCLA, Department of Medicine, Ahmanson-Lovelace Brain Mapping Center, UCLA
| | - JA Bueller
- Center for Neurobiology of Stress, Ahmanson-Lovelace Brain Mapping Center, UCLA, Department of Medicine, Ahmanson-Lovelace Brain Mapping Center, UCLA
| | - B Suyenobu
- Center for Neurobiology of Stress, Ahmanson-Lovelace Brain Mapping Center, UCLA, Department of Medicine, Ahmanson-Lovelace Brain Mapping Center, UCLA
| | - JM Jarcho
- Center for Neurobiology of Stress, Ahmanson-Lovelace Brain Mapping Center, UCLA, Department of Medicine, Ahmanson-Lovelace Brain Mapping Center, UCLA
| | - JA McRoberts
- Center for Neurobiology of Stress, Ahmanson-Lovelace Brain Mapping Center, UCLA, Department of Medicine, Ahmanson-Lovelace Brain Mapping Center, UCLA
| | - B Niesler
- Department of Human Molecular Genetics, University of Heidelberg, Germany
| | - EA Mayer
- Center for Neurobiology of Stress, Ahmanson-Lovelace Brain Mapping Center, UCLA, Department of Medicine, Ahmanson-Lovelace Brain Mapping Center, UCLA, Department of Psychiatry & Biobehavioral Sciences, Ahmanson-Lovelace Brain Mapping Center, UCLA, Brain Research Institute, David Geffen School of Medicine, UCLA
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162
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Abstract
Serotonin (5-HT)3 receptors are the only ligand-gated ion channel of the 5-HT receptors family. They are present both in the peripheral and central nervous system and are localized in several areas involved in mood regulation (e.g., hippocampus or prefrontal cortex). Moreover, they are involved in regulation of neurotransmitter systems implicated in the pathophysiology of major depression (e.g., dopamine or GABA). Clinical and preclinical studies have suggested that 5-HT3 receptors may be a relevant target in the treatment of affective disorders. 5-HT3 receptor agonists seem to counteract the effects of antidepressants in non-clinical models, whereas 5-HT3 receptor antagonists, such as ondansetron, present antidepressant-like activities. In addition, several antidepressants, such as mirtazapine, also target 5-HT3 receptors. In this review, we will report major advances in the research of 5-HT3 receptor's roles in neuropsychiatric disorders, with special emphasis on mood and anxiety disorders.
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163
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Psychotropic and nonpsychotropic cannabis derivatives inhibit human 5-HT(3A) receptors through a receptor desensitization-dependent mechanism. Neuroscience 2011; 184:28-37. [PMID: 21477640 DOI: 10.1016/j.neuroscience.2011.03.066] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2011] [Revised: 03/28/2011] [Accepted: 03/29/2011] [Indexed: 12/17/2022]
Abstract
Δ⁹ tetrahydrocannabinol (THC) and cannabidiol (CBD) are the principal psychoactive and nonpsychoactive components of cannabis. While most THC-induced behavioral effects are thought to depend on endogenous cannabinoid 1 (CB1) receptors, the molecular targets for CBD remain unclear. Here, we report that CBD and THC inhibited the function of human 5-HT(3A) receptors (h5-HT(3A)Rs) expressed in HEK 293 cells. The magnitude of THC and CBD inhibition was maximal 5 min after a continuous incubation with cannabinoids. The EC₅₀ values for CBD and THC-induced inhibition were 110 nM and 322 nM, respectively in HEK 293 cells expressing h5-HT(3A)Rs. In these cells, CBD and THC did not stimulate specific [³⁵S]-GTP-γs binding in membranes, suggesting that the inhibition by cannabinoids is unlikely mediated by a G-protein dependent mechanism. On the other hand, both CBD and THC accelerated receptor desensitization kinetics without significantly changing activation time. The extent of cannabinoid inhibition appeared to depend on receptor desensitization. Reducing receptor desensitization by nocodazole, 5-hydroxyindole and a point-mutation in the large cytoplasmic domain of the receptor significantly decreased CBD-induced inhibition. Similarly, the magnitude of THC and CBD-induced inhibition varied with the apparent desensitization rate of h5-HT(3A)Rs expressed in Xenopus oocytes. For instance, with increasing amount of h5-HT(3A)R cRNA injected into the oocytes, the receptor desensitization rate at steady state decreased. THC and CBD-induced inhibition was correlated with the change in the receptor desensitization rate. Thus, CBD and THC inhibit h5-HT(3A) receptors through a mechanism that is dependent on receptor desensitization.
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164
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Serotonin receptors and heart valve disease--it was meant 2B. Pharmacol Ther 2011; 132:146-57. [PMID: 21440001 DOI: 10.1016/j.pharmthera.2011.03.008] [Citation(s) in RCA: 144] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2011] [Accepted: 03/07/2011] [Indexed: 11/24/2022]
Abstract
Carcinoid heart disease was one of the first valvular pathologies studied in molecular detail, and early research identified serotonin produced by oncogenic enterochromaffin cells as the likely culprit in causing changes in heart valve tissue. Researchers and physicians in the mid-1960s noted a connection between the use of several ergot-derived medications with structures similar to serotonin and the development of heart valve pathologies similar to those observed in carcinoid patients. The exact serotonergic target that mediated valvular pathogenesis remained a mystery for many years until similar cases were reported in patients using the popular diet drug Fen-Phen in the late 1990s. The Fen-Phen episode sparked renewed interest in serotonin-mediated valve disease, and studies led to the identification of the 5-HT(2B) receptor as the likely molecular target leading to heart valve tissue fibrosis. Subsequent studies have identified numerous other activators of the 5-HT(2B) receptor, and consequently, the use of many of these molecules has been linked to heart valve disease. Herein, we: review the molecular properties of the 5-HT(2B) receptor including factors that differentiate the 5-HT(2B) receptor from other 5-HT receptor subtypes, discuss the studies that led to the identification of the 5-HT(2B) receptor as the mediator of heart valve disease, present current efforts to identify potential valvulopathogens by screening for 5-HT(2B) receptor activity, and speculate on potential therapeutic benefits of 5-HT(2B) receptor targeting.
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165
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Morton RA, Luo G, Davis MI, Hales TG, Lovinger DM. Fluorophore assisted light inactivation (FALI) of recombinant 5-HT₃A receptor constitutive internalization and function. Mol Cell Neurosci 2011; 47:79-92. [PMID: 21338684 DOI: 10.1016/j.mcn.2011.02.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2010] [Revised: 02/03/2011] [Accepted: 02/14/2011] [Indexed: 01/06/2023] Open
Abstract
Fluorescent proteins and molecules are now widely used to tag and visualize proteins resulting in an improved understanding of protein trafficking, localization, and function. In addition, fluorescent tags have also been used to inactivate protein function in a spatially and temporally-defined manner, using a technique known as fluorophore-assisted light inactivation (FALI) or chromophore-assisted light inactivation (CALI). In this study we tagged the serotonin₃ A subunit with the α-bungarotoxin binding sequence (BBS) and subsequently labeled 5-HT₃A/BBS receptors with fluorescently conjugated α-bungarotoxin in live cells. We show that 5-HT₃A/BBS receptors are constitutively internalized in the absence of an agonist and internalization as well as receptor function are inhibited by fluorescence. The fluorescence-induced disruption of function and internalization was reduced with oxygen radical scavengers suggesting the involvement of reactive oxygen species, implicating the FALI process. Furthermore, these data suggest that intense illumination during live-cell microscopy may result in inadvertent FALI and inhibition of protein trafficking.
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Affiliation(s)
- Russell A Morton
- Laboratory for Integrative Neuroscience, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Rockville, MD 20852, USA
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166
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Discovery of new anti-depressants from structurally novel 5-HT3 receptor antagonists: Design, synthesis and pharmacological evaluation of 3-ethoxyquinoxalin-2-carboxamides. Bioorg Med Chem Lett 2011; 21:1253-6. [DOI: 10.1016/j.bmcl.2010.12.064] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2010] [Revised: 12/13/2010] [Accepted: 12/15/2010] [Indexed: 11/22/2022]
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167
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Navailles S, De Deurwaerdère P. Presynaptic control of serotonin on striatal dopamine function. Psychopharmacology (Berl) 2011; 213:213-42. [PMID: 20953589 DOI: 10.1007/s00213-010-2029-y] [Citation(s) in RCA: 86] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/26/2010] [Accepted: 09/14/2010] [Indexed: 11/27/2022]
Abstract
RATIONALE The influences of the serotonergic system on dopamine (DA) neuron activity have received considerable attention during the last three decades due to the real opportunity to improve disorders related to central DA neuron dysfunctions such as Parkinson's disease, schizophrenia, or drug abuse with serotonergic drugs. Numerous biochemical and behavioral data indicate that serotonin (5-HT) affects dopaminergic terminal function in the striatum. OBJECTIVE The authors propose a thorough examination of data showing controversial effects induced by striatal 5-HT on dopaminergic activity. RESULTS Inhibitory and excitatory effects of exogenous 5-HT have been reported on DA release and synthesis, involving various striatal 5-HT receptors. 5-HT also promotes an efflux of DA through reversal of the direction of DA transport. By analogy with the mechanism of action described for amphetamine, the consequences of 5-HT entering DA terminals might explain both the excitatory and inhibitory effects of 5-HT on presynaptic DA terminal activity, but the physiological relevance of this mechanism is far from clear. The recent data suggest that the endogenous 5-HT system affects striatal DA release in a state-dependent manner associated with the conditional involvement of various 5-HT receptors such as 5-HT(2A), 5-HT(2C), 5-HT(3), and 5-HT(4) receptors. CONCLUSION Methodological and pharmacological issues have prevented a comprehensive overview of the influence of 5-HT on striatal DA activity. The distribution of striatal 5-HT receptors and their restricted influence on DA neuron activity suggest that the endogenous 5-HT system exerts multiple and subtle influences on DA-mediated behaviors.
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Affiliation(s)
- Sylvia Navailles
- Unité Mixte de Recherche Centre National de la Recherche Scientifique 5227, Université Victor Segalen Bordeaux 2, Bordeaux, France
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168
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Roth BL. Irving Page Lecture: 5-HT(2A) serotonin receptor biology: interacting proteins, kinases and paradoxical regulation. Neuropharmacology 2011; 61:348-54. [PMID: 21288474 DOI: 10.1016/j.neuropharm.2011.01.012] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2010] [Revised: 11/28/2010] [Accepted: 01/10/2011] [Indexed: 01/04/2023]
Abstract
5-Hydroxytryptamine(2A) (5-HT(2A)) serotonin receptors are important pharmacological targets for a large number of central nervous system and peripheral serotonergic medications. In this review article I summarize work mainly from my lab regarding serotonin receptor anatomy, pharmacology, signaling and regulation. I highlight the role of serotonin receptor interacting proteins and the emerging paradigm of G-protein coupled receptor functional selectivity.
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Affiliation(s)
- Bryan L Roth
- Department of Pharmacology, Program in Neurosciences, Lineberger Cancer Center, NIMH Psychoactive Drug Screening Program, and Division of Medicinal Chemistry and Natural Products, Room 4072, Genetic Medicine Building, University of North Carolina Chapel Hill Medical School, Chapel Hill, NC 27514, USA.
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Yamauchi JG, Nemecz Á, Nguyen QT, Muller A, Schroeder LF, Talley TT, Lindstrom J, Kleinfeld D, Taylor P. Characterizing ligand-gated ion channel receptors with genetically encoded Ca2++ sensors. PLoS One 2011; 6:e16519. [PMID: 21305050 PMCID: PMC3030600 DOI: 10.1371/journal.pone.0016519] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2010] [Accepted: 12/21/2010] [Indexed: 11/23/2022] Open
Abstract
We present a cell based system and experimental approach to characterize agonist and antagonist selectivity for ligand-gated ion channels (LGIC) by developing sensor cells stably expressing a Ca2+ permeable LGIC and a genetically encoded Förster (or fluorescence) resonance energy transfer (FRET)-based calcium sensor. In particular, we describe separate lines with human α7 and human α4β2 nicotinic acetylcholine receptors, mouse 5-HT3A serotonin receptors and a chimera of human α7/mouse 5-HT3A receptors. Complete concentration-response curves for agonists and Schild plots of antagonists were generated from these sensors and the results validate known pharmacology of the receptors tested. Concentration-response relations can be generated from either the initial rate or maximal amplitudes of FRET-signal. Although assaying at a medium throughput level, this pharmacological fluorescence detection technique employs a clonal line for stability and has versatility for screening laboratory generated congeners as agonists or antagonists on multiple subtypes of ligand-gated ion channels. The clonal sensor lines are also compatible with in vivo usage to measure indirectly receptor activation by endogenous neurotransmitters.
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Affiliation(s)
- John G. Yamauchi
- Department of Pharmacology, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California San Diego, La Jolla, California, United States of America
- Biomedical Sciences Graduate Program, University of California San Diego, La Jolla, California, United States of America
| | - Ákos Nemecz
- Department of Pharmacology, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California San Diego, La Jolla, California, United States of America
- Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, California, United States of America
| | - Quoc Thang Nguyen
- Department of Physics, University of California San Diego, La Jolla, California, United States of America
| | - Arnaud Muller
- Department of Physics, University of California San Diego, La Jolla, California, United States of America
| | - Lee F. Schroeder
- Department of Physics, University of California San Diego, La Jolla, California, United States of America
| | - Todd T. Talley
- Department of Pharmacology, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California San Diego, La Jolla, California, United States of America
| | - Jon Lindstrom
- Department of Neurosciences, School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - David Kleinfeld
- Department of Physics, University of California San Diego, La Jolla, California, United States of America
| | - Palmer Taylor
- Department of Pharmacology, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California San Diego, La Jolla, California, United States of America
- * E-mail:
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Massoura AN, Dover TJ, Newman AS, Barnes NM. The identification of N-glycosylated residues of the human 5-HT3B receptor subunit: importance for cell membrane expression. J Neurochem 2011; 116:975-83. [DOI: 10.1111/j.1471-4159.2010.07129.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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171
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XIIth international symposium on radiopharmaceutical chemistry: Abstracts and programme. J Labelled Comp Radiopharm 2010. [DOI: 10.1002/jlcr.2580400801] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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172
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Smit-Rigter LA, Wadman WJ, van Hooft JA. Impaired Social Behavior in 5-HT(3A) Receptor Knockout Mice. Front Behav Neurosci 2010; 4:169. [PMID: 21103015 PMCID: PMC2987632 DOI: 10.3389/fnbeh.2010.00169] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2010] [Accepted: 10/07/2010] [Indexed: 12/26/2022] Open
Abstract
The 5-HT3 receptor is a ligand-gated ion channel expressed on interneurons throughout the brain. So far, analysis of the 5-HT3A knockout mouse revealed changes in nociceptive processing and a reduction in anxiety related behavior. Recently, it was shown that the 5-HT3 receptor is also expressed on Cajal-Retzius cells which play a key role in cortical development and that knockout mice lacking this receptor showed aberrant growth of the dendritic tree of cortical layer II/III pyramidal neurons. Other mouse models in which serotonergic signaling was disrupted during development showed similar morphological changes in the cortex, and in addition, also deficits in social behavior. Here, we subjected male and female 5-HT3A knockout mice and their non-transgenic littermates to several tests of social behavior. We found that 5-HT3A knockout mice display impaired social communication in the social transmission of food preference task. Interestingly, we showed that in the social interaction test only female 5-HT3A knockout mice spent less time in reciprocal social interaction starting after 5 min of testing. Moreover, we observed differences in preference for social novelty for male and female 5-HT3A knockout mice during the social approach test. However, no changes in olfaction, exploratory activity and anxiety were detected. These results indicate that the 5-HT3A knockout mouse displays impaired social behavior with specific changes in males and females, reminiscent to other mouse models in which serotonergic signaling is disturbed in the developing brain.
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Affiliation(s)
- Laura A Smit-Rigter
- Center for Neuroscience, Swammerdam Institute for Life Sciences, University of Amsterdam Amsterdam, Netherlands
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173
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Gatt JM, Nemeroff CB, Schofield PR, Paul RH, Clark CR, Gordon E, Williams LM. Early life stress combined with serotonin 3A receptor and brain-derived neurotrophic factor valine 66 to methionine genotypes impacts emotional brain and arousal correlates of risk for depression. Biol Psychiatry 2010; 68:818-24. [PMID: 20728877 DOI: 10.1016/j.biopsych.2010.06.025] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/17/2010] [Revised: 05/28/2010] [Accepted: 06/24/2010] [Indexed: 12/25/2022]
Abstract
BACKGROUND Depression will be the second largest burden of disease by 2020. Developing new tools for identifying risk and ultimately prevention of depression relies on elucidating the integrative relationships between susceptibility markers from gene-stress interactions and how they impact emotional brain and arousal systems. They have largely been studied in isolation. METHODS We examined how genetic (brain-derived neurotrophic factor [BDNF] valine 66 to methionine [Val66Met] and serotonin receptor gene 3A [HTR3A]) and early life stress susceptibility factors interact in predicting electroencephalogram (EEG) asymmetry, emotion-elicited heart rate, and self-reported negativity bias, each correlates of risk for depression. Caucasian volunteers (n = 363) were derived from the Brain Resource International Database, via the Brain Research And Integrative Neuroscience Network. RESULTS Individuals with both BDNF methionine and HTR3A CC risk genotypes and early life stressors demonstrated a profile of elevated emotion-elicited heart rate and right frontal hyper-activation with right parietotemporal hypoactivation in EEG asymmetry. Elevations in heart rate were a moderator of negativity bias. CONCLUSIONS The findings provide new evidence that these gene-stress susceptibility factors contribute to a brain-arousal profile indicative of risk for depression. They are a step toward identifying biological markers for detecting risk before overt symptoms. It would be valuable for future studies to examine comorbidity and specificity issues; for instance, whether these gene-stress factors contribute in different ways to the partially distinct EEG asymmetry profiles found with anxiety.
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Affiliation(s)
- Justine M Gatt
- Brain Dynamics Center, University of Sydney Medical School and Westmead Millennium Institute, Australia
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174
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Wallace TL, Callahan PM, Tehim A, Bertrand D, Tombaugh G, Wang S, Xie W, Rowe WB, Ong V, Graham E, Terry AV, Rodefer JS, Herbert B, Murray M, Porter R, Santarelli L, Lowe DA. RG3487, a Novel Nicotinic α7 Receptor Partial Agonist, Improves Cognition and Sensorimotor Gating in Rodents. J Pharmacol Exp Ther 2010; 336:242-53. [DOI: 10.1124/jpet.110.171892] [Citation(s) in RCA: 104] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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175
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Gui Z, Zhang Q, Liu J, Ali U, Li L, Wang Y, Wang T, Chen L, Hou C, Fan L. In vivo modulation of the firing activity of putative slow- and fast-spiking interneurons in the medial prefrontal cortex by 5-HT3 receptors in 6-hydroxydopamine-induced Parkinsonian rats. Neuroscience 2010; 169:1315-25. [DOI: 10.1016/j.neuroscience.2010.05.059] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2010] [Revised: 05/17/2010] [Accepted: 05/24/2010] [Indexed: 10/19/2022]
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176
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Gatt JM, Williams LM, Schofield PR, Dobson-Stone C, Paul RH, Grieve SM, Clark CR, Gordon E, Nemeroff CB. Impact of the HTR3A gene with early life trauma on emotional brain networks and depressed mood. Depress Anxiety 2010; 27:752-9. [PMID: 20694966 DOI: 10.1002/da.20726] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND The risk for mental illnesses such as depression is increasingly conceptualized as the product of gene-environment interactions and their impact on brain structure and function. The role of serotonin 3A receptor gene (HTR3A -42C>T polymorphism) and its interaction with early life stress (ELS) was investigated in view of the receptor's localization to brain regions central to emotion processing. METHODS Fronto-limbic grey matter (GM) loss was measured using magnetic resonance imaging and assessed using voxel-based morphometry analysis in 397 nonclinical individuals from the Brain Resource International Database. Negative mood symptoms were also assessed. RESULTS The HTR3A CC genotype group, compared to the T carriers, demonstrated comparative loss to GM in hippocampal structures, which extended to the frontal cortices for those CC genotype individuals also exposed to ELS. Elevations in depressed mood were also evident. CONCLUSIONS These findings suggest that the HTR3A CC genotype may be associated with alterations in brain structures central to emotion processing, particularly when exposed to stress, and further highlight the potential role of the serotonin system in the pathophysiology of affective disorders. In contrast, those individuals with the T allele, in particular the TT genotype, may be more protected from such alterations combined with minimal exposure to ELS events.
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Affiliation(s)
- Justine M Gatt
- The Brain Dynamics Center, Westmead Millennium Institute & Discipline of Psychiatry, University of Sydney at Westmead Hospital, New South Wales, Australia
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177
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Nyce HL, Stober ST, Abrams CF, White MM. Mapping spatial relationships between residues in the ligand-binding domain of the 5-HT3 receptor using a molecular ruler. Biophys J 2010; 98:1847-55. [PMID: 20441748 DOI: 10.1016/j.bpj.2010.01.034] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2009] [Revised: 01/11/2010] [Accepted: 01/14/2010] [Indexed: 12/24/2022] Open
Abstract
The serotonin 5-HT(3) receptor (5-HT(3)R) is a member of the Cys-loop ligand-gated ion channel family. We used a combination of site-directed mutagenesis, homology modeling, and ligand-docking simulations to analyze antagonist-receptor interactions. Mutation of E236, which is near loop C of the binding site, to aspartate prevents expression of the receptor on the cell surface, and no specific ligand binding can be detected. On the other hand, mutation to glutamine, asparagine, or alanine produces receptors that are expressed on the cell surface, but decreases receptor affinity for the competitive antagonist d-tubocurarine (dTC) 5-35-fold. The results of a double-mutant cycle analysis employing a panel of dTC analogs to identify specific points of interactions between the dTC analogs and E236 are consistent with E236 making a direct physical interaction with the 12 -OH of dTC. dTC is a rigid molecule of known three-dimensional structure. Together with previous studies linking other regions of dTC to specific residues in the binding site, these data allow us to define the relative spatial arrangement of three different residues in the ligand-binding site: R92 (loop D), N128 (loop A), and E236 (near loop C). Molecular modeling employing these distance constraints followed by molecular-dynamics simulations produced a dTC/receptor complex consistent with the experimental data. The use of the rigid ligands as molecular rulers in conjunction with double-mutant cycle analysis provides a means of mapping the relative positions of various residues in the ligand-binding site of any ligand-receptor complex, and thus is a useful tool for delineating the architecture of the binding site.
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Affiliation(s)
- Heather L Nyce
- Department of Biochemistry, Drexel University College of Medicine, Philadelphia, Pennsylvania, USA
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178
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Walstab J, Rappold G, Niesler B. 5-HT(3) receptors: role in disease and target of drugs. Pharmacol Ther 2010; 128:146-69. [PMID: 20621123 DOI: 10.1016/j.pharmthera.2010.07.001] [Citation(s) in RCA: 151] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2010] [Accepted: 06/21/2010] [Indexed: 12/19/2022]
Abstract
Serotonin type 3 (5-HT(3)) receptors are pentameric ion channels belonging to the superfamily of Cys-loop receptors. Receptor activation either leads to fast excitatory responses or modulation of neurotransmitter release depending on their neuronal localisation. 5-HT(3) receptors are known to be expressed in the central nervous system in regions involved in the vomiting reflex, processing of pain, the reward system, cognition and anxiety control. In the periphery they are present on a variety of neurons and immune cells. 5-HT(3) receptors are known to be involved in emesis, pain disorders, drug addiction, psychiatric and GI disorders. Progress in molecular genetics gives direction to personalised medical strategies for treating complex diseases such as psychiatric and functional GI disorders and unravelling individual drug responses in pharmacogenetic approaches. Here we discuss the molecular basis of 5-HT(3) receptor diversity at the DNA and protein level, of which our knowledge has greatly extended in the last decade. We also evaluate their role in health and disease and describe specific case-control studies addressing the involvement of polymorphisms of 5-HT3 subunit genes in complex disorders and responses to drugs. Furthermore, we focus on the actual state of the pharmacological knowledge concerning not only classical 5-HT(3) antagonists--the setrons--but also compounds of various substance classes targeting 5-HT(3) receptors such as anaesthetics, opioids, cannabinoids, steroids, antidepressants and antipsychotics as well as natural compounds derived from plants. This shall point to alternative treatment options modulating the 5-HT(3) receptor system and open new possibilities for drug development in the future.
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Affiliation(s)
- Jutta Walstab
- Department of Human Molecular Genetics, University of Heidelberg, Im Neuenheimer Feld 366, 69120 Heidelberg, Germany
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179
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Toyohara J, Hashimoto K. α7 Nicotinic Receptor Agonists: Potential Therapeutic Drugs for Treatment of Cognitive Impairments in Schizophrenia and Alzheimer's Disease. THE OPEN MEDICINAL CHEMISTRY JOURNAL 2010; 4:37-56. [PMID: 21249164 PMCID: PMC3023065 DOI: 10.2174/1874104501004010037] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/15/2009] [Revised: 10/23/2009] [Accepted: 10/30/2009] [Indexed: 01/19/2023]
Abstract
Accumulating evidence suggests that α7 nicotinic receptors (α7 nAChRs), a subtype of nAChRs, play a role in the pathophysiology of neuropsychiatric diseases, including schizophrenia and Alzheimer's disease (AD). A number of psychopharmacological and genetic studies shown that α7 nAChRs play an important role in the deficits of P50 auditory evoked potential in patients with schizophrenia, and that (α nAChR agonists would be potential therapeutic drugs for cognitive impairments associated with P50 deficits in schizophrenia. Furthermore, some studies have demonstrated that α7 nAChRs might play a key role in the amyloid-β (Aβ)-mediated pathology of AD, and that α7 nAChR agonists would be potential therapeutic drugs for Aβ deposition in the brains of patients with AD. Interestingly, the altered expression of α7 nAChRs in the postmortem brain tissues from patients with schizophrenia and AD has been reported. Based on all these findings, selective α7 nAChR agonists can be considered potential therapeutic drugs for cognitive impairments in both schizophrenia and AD. In this article, we review the recent research into the role of α7 nAChRs in the pathophysiology of these diseases and into the potential use of novel α7 nAChR agonists as therapeutic drugs.
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Affiliation(s)
- Jun Toyohara
- Division of Clinical Neuroscience, Chiba University Center for Forensic Mental Health, Chiba, Japan
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180
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Carrillo M, Ricci LA, Schwartzer JJ, Melloni RH. Immunohistochemical characterization of 5-HT3A receptors in the Syrian hamster forebrain. Brain Res 2010; 1329:67-81. [DOI: 10.1016/j.brainres.2010.02.038] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2009] [Revised: 02/04/2010] [Accepted: 02/09/2010] [Indexed: 12/24/2022]
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181
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Rajkumar R, Mahesh R. The auspicious role of the 5-HT3 receptor in depression: a probable neuronal target? J Psychopharmacol 2010; 24:455-69. [PMID: 20123937 DOI: 10.1177/0269881109348161] [Citation(s) in RCA: 82] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The serotonergic mechanisms have been successfully utilized by the majority of antidepressant drug discovery programmes, while the search for newer targets remains persistent. The present review focused on the serotonin type-3 receptor, the only ion channel subtype in the serotonin family. Behavioural, neurochemical, electrophysiological and molecular analyses, including the results from our laboratory, provided substantial evidence that rationalizes the correlation between serotonin type-3 receptor modulation and rodent depressive-like behaviour. Nevertheless, the reports on polymorphism of serotonin type-3 receptor genes and data from clinical studies (on serotonin type-3 receptor antagonists) were insufficient to corroborate the involvement of this receptor in the neurobiology of depression. The preclinical and clinical studies that have contradicted the antidepressant-like effects of serotonin type-3 receptor antagonists and the reasons underlying such disagreement were discussed. Finally, this critical review commended the serotonin type-3 receptor as a candidate neuronal antidepressant drug target.
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182
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Abstract
Functional studies of the ligand gated ion channel family (nicotinic acetylcholine, serotonin Type 3, glycine and GABA receptors) along with the crystal structure of the acetylcholine binding protein (AChBP) and molecular dynamics simulations of the nAChR structure have resulted in a structural model in which the agonist-binding pocket comprises six loops (A-F) contributed by adjacent subunits. It is presumed that the binding of agonist results in a local structural rearrangement that is then transduced to the gate, causing the pore to open. Efforts are underway to better define the specific roles of the six binding loops. Several studies have suggested Loop F may play a direct role in linking the structural rearrangement within the binding pocket to the gate, although other investigations have indicated Loop F may be crucial for locking the agonist molecule into the binding site. This review will focus on the controversy surrounding the role of Loop F during GABA receptor activation.
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Affiliation(s)
- Alpa Khatri
- Department of Physiology, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA
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183
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O'Donnell CJ, Rogers BN, Bronk BS, Bryce DK, Coe JW, Cook KK, Duplantier AJ, Evrard E, Hajós M, Hoffmann WE, Hurst RS, Maklad N, Mather RJ, McLean S, Nedza FM, O'Neill BT, Peng L, Qian W, Rottas MM, Sands SB, Schmidt AW, Shrikhande AV, Spracklin DK, Wong DF, Zhang A, Zhang L. Discovery of 4-(5-methyloxazolo[4,5-b]pyridin-2-yl)-1,4-diazabicyclo[3.2.2]nonane (CP-810,123), a novel alpha 7 nicotinic acetylcholine receptor agonist for the treatment of cognitive disorders in schizophrenia: synthesis, SAR development, and in vivo efficacy in cognition models. J Med Chem 2010; 53:1222-37. [PMID: 20043678 DOI: 10.1021/jm9015075] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A novel alpha 7 nAChR agonist, 4-(5-methyloxazolo[4,5-b]pyridin-2-yl)-1,4-diazabicyclo[3.2.2]nonane (24, CP-810,123), has been identified as a potential treatment for cognitive deficits associated with psychiatric or neurological conditions including schizophrenia and Alzheimer's disease. Compound 24 is a potent and selective compound with excellent pharmaceutical properties. In rodent, the compound displays high oral bioavailability and excellent brain penetration affording high levels of receptor occupancy and in vivo efficacy in auditory sensory gating and novel object recognition. The structural diversity of this compound and its preclinical in vitro and in vivo package support the hypothesis that alpha 7 nAChR agonists may have potential as a pharmacotherapy for the treatment of cognitive deficits in schizophrenia.
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Affiliation(s)
- Christopher J O'Donnell
- Pfizer Global Research and Development, Groton Laboratories, Eastern Point Road, Groton, Connecticut 06340, USA.
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184
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Classification and Signaling Characteristics of 5-HT Receptors. HANDBOOK OF BEHAVIORAL NEUROSCIENCE 2010. [DOI: 10.1016/s1569-7339(10)70073-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
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185
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Mengod G, Cortés R, Vilaró MT, Hoyer D. Distribution of 5-HT Receptors in the Central Nervous System. HANDBOOK OF BEHAVIORAL NEUROSCIENCE 2010. [DOI: 10.1016/s1569-7339(10)70074-6] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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186
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Saroya R, Smith R, Seymour C, Mothersill C. Injection of resperpine into zebrafish, prevents fish to fish communication of radiation-induced bystander signals: confirmation in vivo of a role for serotonin in the mechanism. Dose Response 2009; 8:317-30. [PMID: 20877486 DOI: 10.2203/dose-response.09-043.saroya] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
Serotonin (5-HT) has been implicated as a potential modulator of the bystander effect in cell cultures. To assess the relevance of serotonin in vivo experiments were done with the zebrafish (Danio rerio). This species, when irradiated, transmits bystander signals to non-irradiated fish. The animals were injected with reserpine, an inhibitor of serotonin at a dose of 80mg/kg of body mass. The results show that reserpine treated fish had only 27% of the serotonin in non-treated fish. Skin tissue samples were collected from the fish and assayed for bystander signal production using a reporter bioassay. Reserpine prevented the production and communication of signals between fish. Intracellular calcium flux, identified as a bystander response in the reporter cells confirmed this. Medium harvested from tissues of X-rayed fish and their bystanders, showed an oscillating pattern of calcium flux. Samples from X-rayed fish pretreated with reserpine produced a chaotic pattern of random fluctuations in the reporter cells, while their bystander fish led to increased calcium, but no oscillations. These results suggest that 5-HT is involved in bystander signalling in zebrafish, and by decreasing the amount of available 5-HT the bystander effect can be blocked.
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Affiliation(s)
- Rohin Saroya
- Department of Medical Physics and Applied Radiation Sciences, McMaster University, Hamilton, Ontario, Canada
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187
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Corradi J, Gumilar F, Bouzat C. Single-channel kinetic analysis for activation and desensitization of homomeric 5-HT(3)A receptors. Biophys J 2009; 97:1335-45. [PMID: 19720021 DOI: 10.1016/j.bpj.2009.06.018] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2008] [Revised: 06/10/2009] [Accepted: 06/15/2009] [Indexed: 10/25/2022] Open
Abstract
The 5-HT(3)A receptor is a member of the Cys-loop family of ligand-gated ion channels. To perform kinetic analysis, we mutated the 5-HT3A subunit to obtain a high-conductance form so that single-channel currents can be detected. At all 5-HT concentrations (> 0.1 microM), channel activity appears as openings in quick succession that form bursts, which coalesce into clusters. By combining single-channel and macroscopic data, we generated a kinetic model that perfectly describes activation, deactivation, and desensitization. The model shows that full activation arises from receptors with three molecules of agonist bound. It reveals an earlier conformational change of the fully liganded receptor that occurs while the channel is still closed. From this pre-open closed state, the receptor enters into an open-closed cycle involving three open states, which form the cluster whose duration parallels the time constant of desensitization. A similar model lacking the pre-open closed state can describe the data only if the opening rates are fixed to account for the slow activation rate. The application of the model to M4 mutant receptors shows that position 10' contributes to channel opening and closing rates. Thus, our kinetic model provides a foundation for understanding structural bases of activation and drug action.
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Affiliation(s)
- Jeremías Corradi
- Instituto de Investigaciones Bioquímicas de Bahía Blanca, Universidad Nacional del Sur/Consejo Nacional de Investigaciones Científicas y Técnicas, Bahía Blanca, Argentina
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188
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Anaesthetic mechanisms: update on the challenge of unravelling the mystery of anaesthesia. Eur J Anaesthesiol 2009; 26:807-20. [PMID: 19494779 DOI: 10.1097/eja.0b013e32832d6b0f] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
General anaesthesia is administered each day to thousands of patients worldwide. Although more than 160 years have passed since the first successful public demonstration of anaesthesia, a detailed understanding of the anaesthetic mechanism of action of these drugs is still lacking. An important early observation was the Meyer-Overton correlation, which associated the potency of an anaesthetic with its lipid solubility. This work focuses attention on the lipid membrane as a likely location for anaesthetic action. With the advent of cellular electrophysiology and molecular biology techniques, tools to dissect the components of the lipid membrane have led, in recent years, to the widespread acceptance of proteins, namely receptors and ion channels, as more likely targets for the anaesthetic effect. Yet these accumulated data have not produced a comprehensive explanation for how these drugs produce central nervous system depression. In this review, we follow the story of anaesthesia mechanisms research from its historical roots to the intensely neurophysiological research regarding it today. We will also describe recent findings that identify specific neuroanatomical locations mediating the actions of some anaesthetic agents.
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189
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Tang JS, Qu CL, Huo FQ. The thalamic nucleus submedius and ventrolateral orbital cortex are involved in nociceptive modulation: A novel pain modulation pathway. Prog Neurobiol 2009; 89:383-9. [DOI: 10.1016/j.pneurobio.2009.10.002] [Citation(s) in RCA: 90] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2009] [Revised: 09/27/2009] [Accepted: 10/01/2009] [Indexed: 12/01/2022]
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190
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Pallanti S, Bernardi S, Antonini S, Singh N, Hollander E. Ondansetron augmentation in treatment-resistant obsessive-compulsive disorder: a preliminary, single-blind, prospective study. CNS Drugs 2009; 23:1047-55. [PMID: 19958042 DOI: 10.2165/11530240-000000000-00000] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Serotonin and dopamine neuronal systems have been implicated in the modulation of obsessive-compulsive disorder (OCD) symptoms. About 40% of OCD patients do not respond to first-line selective serotonin reuptake inhibitor (SSRI) treatment; among those, dopamine blocker augmentation has been reported to improve the rate of response by an additional one-third. Given that serotonin 5-HT(3) receptors are indirect inhibitors of cortico-mesolimbic dopamine release, augmentation with the 5-HT(3) receptor antagonist ondansetron in combination with SSRIs and antipsychotics has potential efficacy in treatment-resistant OCD patients. To assess the efficacy and tolerability of ondansetron in combination with SSRIs and antipsychotics in patients with treatment-resistant OCD. In total, 14 patients with a DSM-IV diagnosis of OCD, who were treatment resistant and receiving stable treatment with SSRIs and antipsychotic augmentation, entered a 12-week, single-blind trial of ondansetron. The drug was initiated at a dosage of 0.25 mg twice daily for 6 weeks and was then titrated to 0.5 mg twice daily for 6 weeks. Of the 14 patients, nine (64.3%) experienced a treatment response (> or =25% reduction in the Yale-Brown Obsessive Compulsive Scale [YBOCS] score and a Clinical Global Impressions-Improvement [CGI-I] score of 1 or 2) at 12 weeks. The average reduction in YBOCS-rated symptoms for the whole group was 23.2%. None of the treated patients experienced symptom exacerbation or significant adverse effects. These results suggest that low-dose ondansetron may have promise as an augmentation strategy for some patients with OCD resistant to SSRIs and antipsychotic augmentation, but further controlled trials are required. Trial registration number (ClinicalTrials.gov): NCT00796497.
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Affiliation(s)
- Stefano Pallanti
- Department of Psychiatry, Mount Sinai School of Medicine, New York, New York 10029, USA.
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191
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Gholipour T, Ghasemi M, Riazi K, Ghaffarpour M, Dehpour AR. Seizure susceptibility alteration through 5-HT(3) receptor: modulation by nitric oxide. Seizure 2009; 19:17-22. [PMID: 19942458 DOI: 10.1016/j.seizure.2009.10.006] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2009] [Revised: 10/28/2009] [Accepted: 10/29/2009] [Indexed: 11/16/2022] Open
Abstract
There is some evidence that epileptic seizures could be induced or increased by 5-hydroxytryptamine (5-HT) attenuation, while augmentation of serotonin functions within the brain (e.g. by SSRIs) has been reported to be anticonvulsant. This study was performed to determine the effect of selective 5-HT(3) channel/receptor antagonist granisetron and agonist SR57227 hydrochloride on the pentylenetetrazole (PTZ)-induced seizure threshold in mice. The possible interaction of this effect with nitrergic system was also examined using the nitric oxide (NO) synthase inhibitor N(G)-nitro-l-arginine methyl ester (l-NAME) and the NO precursor l-arginine. SR57227 (10mg/kg, i.p.) significantly increased the seizure threshold compared to control group, while high dose granisetron (10mg/kg, i.p.) proved proconvulsant. Co-administration of sub-effective doses of the 5-HT(3) agonist with l-NAME (5 and 60mg/kg, i.p., respectively) exerted a significant anticonvulsive effect, while sub-effective doses of granisetron (3mg/kg) was observed to have a proconvulsive action with the addition of l-arginine (75mg/kg, i.p.). Our data demonstrate that enhancement of 5-HT(3) receptor function results in as anticonvulsant effect in the PTZ-induced seizure model, and that selective antagonism at the 5-HT(3) receptor yields proconvulsive effects. Furthermore, the NO system may play a role in 5-HT(3) receptor function.
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Affiliation(s)
- Taha Gholipour
- Department of Pharmacology, School of Medicine, Tehran University of Medical Sciences, P.O. Box 13145-784, Tehran, Iran
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192
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Wu DF, Othman NA, Sharp D, Mahendra A, Deeb TZ, Hales TG. A conserved cysteine residue in the third transmembrane domain is essential for homomeric 5-HT3 receptor function. J Physiol 2009; 588:603-16. [PMID: 19933756 DOI: 10.1113/jphysiol.2009.181719] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
The cysteine (Cys) residue at position 312 in the third transmembrane domain (M3) is conserved among 5-hydroxytryptamine type 3 (5-HT(3)) receptor subunits and many other subunits of the nicotinic acetylcholine (nACh) related Cys-loop receptor family, including most of the gamma-aminobutyric acid type A (GABA(A)) and glycine receptor subunits. To elucidate a possible role for the Cys-312 in human 5-HT(3)A receptors, we replaced it with alanine and expressed the 5-HT(3)A(C312A) mutant in HEK293 cells. The mutation resulted in an absence of 5-HT-induced whole-cell current without reducing homopentamer formation, surface expression or 5-HT binding. The 5-HT(3)A(C312A) mutant, when co-expressed with the wild-type 5-HT(3)A subunit, did not affect functional expression of receptors, suggesting that the mutant is not dominant negative. Interestingly, co-expression of 5-HT(3)A(C312A) with 5-HT(3)B led to surface expression of heteropentamers that mediated small 5-HT responses. This suggests that the Cys-312 is essential for homomeric but not heteromeric receptor gating. To further investigate the relationship between residue 312 and gating we replaced it with amino acids located at the equivalent position within other Cys-loop subunits that are either capable or incapable of forming functional homopentamers. Replacement of 5-HT(3)A Cys-312 by Gly or Leu (equivalent residues in the nACh receptor delta and gamma subunits) abolished and severely attenuated function, respectively, whereas replacement by Thr or Ser (equivalent residues in nACh receptor alpha7 and GABA(A) subunits) supported robust function. Thus, 5-HT(3)A residue 312 and equivalent polar residues in the M3 of other Cys-loop subunits are essential determinants of homopentameric gating.
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Affiliation(s)
- Dai-Fei Wu
- Department of Pharmacology & Physiology, George Washington University, Washington, DC 20037, USA
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193
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Sanghvi M, Hamouda AK, Davis MI, Morton RA, Srivastava S, Pandhare A, Duddempudi PK, Machu TK, Lovinger DM, Cohen JB, Blanton MP. Hydrophobic photolabeling studies identify the lipid-protein interface of the 5-HT3A receptor. Biochemistry 2009; 48:9278-86. [PMID: 19715355 DOI: 10.1021/bi901208j] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
A HEK-293 cell line that stably expresses mouse 5-HT(3A)Rs containing a C-terminal extension that confers high-affinity binding of alpha-bungarotoxin (alphaBgTx) was established (alphaBgTx-5-HT(3A)Rs) and used to purify alphaBgTx-5-HT(3A)Rs in a lipid environment for use in structural studies using photoaffinity labeling. alphaBgTx-5-HT(3A)Rs were expressed robustly (60 pmol of [(3)H]BRL-43694 binding sites (approximately 3 microg of receptor) per milligram of protein) and displayed the same functional properties as wild-type receptors (serotonin EC(50) = 5.3 +/- 0.04 microM). While [(125)I]alphaBgTx bound to the alphaBgTx-5-HT(3A)Rs with high affinity (K(d) = 11 nM), application of nonradioactive alphaBgTx (up to 300 microM) had no effect on serotonin-induced current responses. alphaBgTx-5-HT(3A)Rs were purified on an alphaBgTx-derivatized affinity column from detergent extracts in milligram quantities and at approximately 25% purity. The hydrophobic photolabel 3-trifluoromethyl-3-(m-[(125)I]iodophenyl)diazirine ([(125)I]TID) was used to identify the amino acids at the lipid-protein interface of purified and lipid-reconstituted alphaBgTx-5-HT(3A)Rs. [(125)I]TID photoincorporation into the alphaBgTx-5-HT(3A)R subunit was initially mapped to subunit proteolytic fragments of 8 kDa, containing the M4 transmembrane segment and approximately 60% of incorporated (125)I, and 17 kDa, containing the M1-M3 transmembrane segments. Within the M4 segment, [(125)I]TID labeled Ser(451), equivalent to the [(125)I]TID-labeled residue Thr(422) at the lipid-exposed face of the Torpedo nicotinic acetylcholine receptor (nAChR) alpha1M4 alpha-helix. These results provide a first definition of the surface of the 5-HT(3A)R M4 helix that is exposed to lipid and establish that this surface is equivalent to the surface exposed to lipid in the Torpedo nAChR.
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Affiliation(s)
- Mitesh Sanghvi
- Department of Pharmacology and Neuroscience and Center for Membrane Protein Research, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, Texas 79430, USA
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194
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Synthesis and SAR of N-Chlorophenyl Substituted Piperrazinylethyl-aminomethylpyrazoles as 5-HT3AInhibitors. B KOREAN CHEM SOC 2009. [DOI: 10.5012/bkcs.2009.30.11.2707] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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195
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5-HT 3(5-hydroxytryptamine 3). Br J Pharmacol 2009. [DOI: 10.1111/j.1476-5381.2009.00502_2.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
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196
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LGIC. Br J Pharmacol 2009. [DOI: 10.1111/j.1476-5381.2009.00502.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
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197
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Bartos M, Corradi J, Bouzat C. Structural basis of activation of cys-loop receptors: the extracellular-transmembrane interface as a coupling region. Mol Neurobiol 2009; 40:236-52. [PMID: 19859835 DOI: 10.1007/s12035-009-8084-x] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2009] [Accepted: 09/22/2009] [Indexed: 10/25/2022]
Abstract
Cys-loop receptors mediate rapid transmission throughout the nervous system by converting a chemical signal into an electric one. They are pentameric proteins with an extracellular domain that carries the transmitter binding sites and a transmembrane region that forms the ion pore. Their essential function is to couple the binding of the agonist at the extracellular domain to the opening of the ion pore. How the structural changes elicited by agonist binding are propagated through a distance of 50 A to the gate is therefore central for the understanding of the receptor function. A step forward toward the identification of the structures involved in gating has been given by the recently elucidated high-resolution structures of Cys-loop receptors and related proteins. The extracellular-transmembrane interface has attracted attention because it is a structural transition zone where beta-sheets from the extracellular domain merge with alpha-helices from the transmembrane domain. Within this zone, several regions form a network that relays structural changes from the binding site toward the pore, and therefore, this interface controls the beginning and duration of a synaptic response. In this review, the most recent findings on residues and pairwise interactions underlying channel gating are discussed, the main focus being on the extracellular-transmembrane interface.
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Affiliation(s)
- Mariana Bartos
- Instituto de Investigaciones Bioquímicas, UNS-CONICET, Bahía Blanca, Argentina
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198
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Wildeboer KM, Zheng L, Choo KS, Stevens KE. Ondansetron results in improved auditory gating in DBA/2 mice through a cholinergic mechanism. Brain Res 2009; 1300:41-50. [PMID: 19728991 DOI: 10.1016/j.brainres.2009.08.075] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2009] [Revised: 08/14/2009] [Accepted: 08/21/2009] [Indexed: 10/20/2022]
Abstract
The 5-HT(3) receptor antagonist, ondansetron, has been shown to correct the auditory gating deficit in medicated schizophrenia patients. Inhibition of 5-HT(3) receptors releases acetylcholine, the endogenous ligand for nicotinic acetylcholine receptors. The schizophrenia-related auditory gating deficit is modulated, in part, by nicotinic acetylcholine receptors, as is the mouse (DBA/2) model of the deficit. The present study assessed the effects of both acute and chronically administered ondansetron on auditory gating in DBA/2 mice. Auditory gating is defined as a decrease in amplitude of response to the second of a paired identical auditory stimulus presented 0.5 s following an initial auditory stimulus. Acute ondansetron administration at the lowest dose (0.1 mg/kg, IP) tested had no effect, while other doses (0.33 and 1 mg/kg, IP) produced improvements in auditory gating. The improvements were produced through both an increase in response to the first auditory stimulus and a decrease in the response to the second auditory stimulus. Co-administration of an alpha7 nicotinic acetylcholine receptor antagonist, alpha-bungarotoxin, or the alpha4beta2 nicotinic acetylcholine receptor antagonist dihydro-beta-erythroidine, with the 0.33 mg/kg dose of ondansetron blocked the improvement in auditory gating produced by ondansetron alone. There was no difference in response between the chronically injected mice and naive mice. Both showed improved auditory gating, thus, demonstrating no "carry over" effect of daily injections. These data demonstrate that indirect stimulation of nicotinic acetylcholine receptors by ondansetron can improve auditory gating parameters in DBA/2 mice.
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Affiliation(s)
- Kristin M Wildeboer
- Department of Psychiatry, University of Colorado Denver, Mail Stop 8344, RC-1 North, 12800 East 19th Ave. Aurora, CO 80045, USA.
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199
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Rammes G, Hosp C, Eisensamer B, Tanasic S, Nothdurfter C, Zieglgänsberger W, Rupprecht R. Identification of a domain which affects kinetics and antagonistic potency of clozapine at 5-HT3 receptors. PLoS One 2009; 4:e6715. [PMID: 19696922 PMCID: PMC2725292 DOI: 10.1371/journal.pone.0006715] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2009] [Accepted: 07/17/2009] [Indexed: 11/18/2022] Open
Abstract
The widely used atypical antipsychotic clozapine is a potent competitive antagonist at 5-HT3 receptors which may contribute to its unique psychopharmacological profile. Clozapine binds to 5-HT3 receptors of various species. However, the structural requirements of the respective binding site for clozapine remain to be determined. Differences in the primary sequences within the 5-HT3A receptor gene in schizophrenic patients may result in an alteration of the antipsychotic potency and/or the side effect profile of clozapine. To determine these structural requirements we constructed chimeras with different 5-HT3A receptor sequences of murine and human origin and expressed these mutants in human embryonic kidney (HEK) 293 cells. Clozapine antagonises recombinant mouse 5-HT3A receptors with higher potency compared to recombinant human 5-HT3A receptors. 5-HT activation curves and clozapine inhibition curves yielded the parameters EC50 and IC50 for all receptors tested in the range of 0.6–2.7 µM and 1.5–83.3 nM, respectively. The use of the Cheng-Prusoff equation to calculate the dissociation constant Kb values for clozapine revealed that an extracellular sequence (length 86 aa) close to the transmembrane domain M1 strongly determines the binding affinity of clozapine. Kb values of clozapine were significantly lower (0.3–1.1 nM) for receptors containing the murine sequence and higher when compared with receptors containing the respective human sequence (5.8–13.4 nM). Thus, individual differences in the primary sequence of 5-HT3 receptors may be crucial for the antipsychotic potency and/or the side effect profile of clozapine.
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200
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Hazai E, Joshi P, Skoviak EC, Suryanarayanan A, Schulte MK, Bikadi Z. A comprehensive study on the 5-hydroxytryptamine3A receptor binding of agonists serotonin and m-chlorophenylbiguanidine. Bioorg Med Chem 2009; 17:5796-805. [DOI: 10.1016/j.bmc.2009.07.022] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2009] [Revised: 07/06/2009] [Accepted: 07/13/2009] [Indexed: 01/07/2023]
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