1
|
Pagonabarraga J, Bejr-Kasem H, Martinez-Horta S, Kulisevsky J. Parkinson disease psychosis: from phenomenology to neurobiological mechanisms. Nat Rev Neurol 2024; 20:135-150. [PMID: 38225264 DOI: 10.1038/s41582-023-00918-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/13/2023] [Indexed: 01/17/2024]
Abstract
Parkinson disease (PD) psychosis (PDP) is a spectrum of illusions, hallucinations and delusions that are associated with PD throughout its disease course. Psychotic phenomena can manifest from the earliest stages of PD and might follow a continuum from minor hallucinations to structured hallucinations and delusions. Initially, PDP was considered to be a complication associated with dopaminergic drug use. However, subsequent research has provided evidence that PDP arises from the progression of brain alterations caused by PD itself, coupled with the use of dopaminergic drugs. The combined dysfunction of attentional control systems, sensory processing, limbic structures, the default mode network and thalamocortical connections provides a conceptual framework to explain how new incoming stimuli are incorrectly categorized, and how aberrant hierarchical predictive processing can produce false percepts that intrude into the stream of consciousness. The past decade has seen the publication of new data on the phenomenology and neurobiological basis of PDP from the initial stages of the disease, as well as the neurotransmitter systems involved in PDP initiation and progression. In this Review, we discuss the latest clinical, neuroimaging and neurochemical evidence that could aid early identification of psychotic phenomena in PD and inform the discovery of new therapeutic targets and strategies.
Collapse
Affiliation(s)
- Javier Pagonabarraga
- Movement Disorder Unit, Neurology Department, Hospital de la Santa Creu i Sant Pau, Barcelona, Spain.
- Department of Medicine, Autonomous University of Barcelona, Barcelona, Spain.
- Sant Pau Biomedical Research Institute (IIB-Sant Pau), Barcelona, Spain.
- Centro de Investigación en Red - Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain.
| | - Helena Bejr-Kasem
- Movement Disorder Unit, Neurology Department, Hospital de la Santa Creu i Sant Pau, Barcelona, Spain
- Department of Medicine, Autonomous University of Barcelona, Barcelona, Spain
- Sant Pau Biomedical Research Institute (IIB-Sant Pau), Barcelona, Spain
- Centro de Investigación en Red - Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain
| | - Saul Martinez-Horta
- Movement Disorder Unit, Neurology Department, Hospital de la Santa Creu i Sant Pau, Barcelona, Spain
- Department of Medicine, Autonomous University of Barcelona, Barcelona, Spain
- Sant Pau Biomedical Research Institute (IIB-Sant Pau), Barcelona, Spain
- Centro de Investigación en Red - Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain
| | - Jaime Kulisevsky
- Movement Disorder Unit, Neurology Department, Hospital de la Santa Creu i Sant Pau, Barcelona, Spain
- Department of Medicine, Autonomous University of Barcelona, Barcelona, Spain
- Sant Pau Biomedical Research Institute (IIB-Sant Pau), Barcelona, Spain
- Centro de Investigación en Red - Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain
| |
Collapse
|
2
|
Tsitsipa E, Rogers J, Casalotti S, Belessiotis-Richards C, Zubko O, Weil RS, Howard R, Bisby JA, Reeves S. Selective 5HT3 antagonists and sensory processing: a systematic review. Neuropsychopharmacology 2022; 47:880-890. [PMID: 35017671 PMCID: PMC8882165 DOI: 10.1038/s41386-021-01255-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/16/2021] [Revised: 12/09/2021] [Accepted: 12/16/2021] [Indexed: 12/04/2022]
Abstract
Ondansetron is a selective serotonin (5HT3) receptor antagonist that is under evaluation as an adjunctive treatment for schizophrenia, and a novel treatment for hallucinations in Parkinson's disease. Ondansetron reverses sensory gating deficits and improves visuoperceptual processing in animal models of psychosis, but it is unclear to what extent preclinical findings have been replicated in humans. We systematically reviewed human studies that evaluated the effects of ondansetron and other 5HT3 receptor antagonists on sensory gating deficits or sensory processing. Of 11 eligible studies, eight included patients with schizophrenia who were chronically stable on antipsychotic medication; five measured sensory gating using the P50 suppression response to a repeated auditory stimulus; others included tests of visuoperceptual function. Three studies in healthy participants included tests of visuoperceptual and sensorimotor function. A consistent and robust finding (five studies) was that ondansetron and tropisetron (5HT3 antagonist and α7-nicotinic receptor partial agonist) improved sensory gating in patients with schizophrenia. Tropisetron also improved sustained visual attention in non-smoking patients. There was inconsistent evidence of the effects of 5HT3 antagonists on other measures of sensory processing, but interpretation was limited by the small number of studies, methodological heterogeneity and the potential confounding effects of concomitant medication in patients. Despite these limitations, we found strong evidence that selective 5HT3 antagonists (with or without direct α7-nicotinic partial agonist effects) improved sensory gating. Future studies should investigate how this relates to potential improvement in neurocognitive symptoms in antipsychotic naive patients with prodromal or milder symptoms, in order to understand the clinical implications.
Collapse
Affiliation(s)
- Eirini Tsitsipa
- grid.83440.3b0000000121901201Division of Psychiatry, University College London, 149 Tottenham Court Road, London, W1T7NF UK
| | - Jonathan Rogers
- grid.83440.3b0000000121901201Division of Psychiatry, University College London, 149 Tottenham Court Road, London, W1T7NF UK ,grid.415717.10000 0001 2324 5535South London and Maudsley NHS Foundation Trust, Bethlem Royal Hospital, Monks Orchard Road, Beckenham, BR3 3BX UK
| | - Sebastian Casalotti
- grid.83440.3b0000000121901201Division of Psychiatry, University College London, 149 Tottenham Court Road, London, W1T7NF UK
| | - Clara Belessiotis-Richards
- grid.83440.3b0000000121901201Division of Psychiatry, University College London, 149 Tottenham Court Road, London, W1T7NF UK
| | - Olga Zubko
- grid.83440.3b0000000121901201Division of Psychiatry, University College London, 149 Tottenham Court Road, London, W1T7NF UK
| | - Rimona S. Weil
- grid.83440.3b0000000121901201Dementia Research Centre, University College London, 8-11 Queen Square, London, WC1N 3AR UK ,grid.83440.3b0000000121901201Wellcome Centre for Human Neuroimaging, University College London, 12 Queen Square, London, WC1N 3AR UK ,grid.436283.80000 0004 0612 2631Movement Disorders Consortium, National Hospital for Neurology and Neurosurgery, Queen Square, London, WC1N 3AR UK
| | - Robert Howard
- grid.83440.3b0000000121901201Division of Psychiatry, University College London, 149 Tottenham Court Road, London, W1T7NF UK
| | - James A. Bisby
- grid.83440.3b0000000121901201Division of Psychiatry, University College London, 149 Tottenham Court Road, London, W1T7NF UK
| | - Suzanne Reeves
- Division of Psychiatry, University College London, 149 Tottenham Court Road, London, W1T7NF, UK.
| |
Collapse
|
3
|
Divanbeigi A, Nasehi M, Vaseghi S, Amiri S, Zarrindast MR. Tropisetron But Not Granisetron Ameliorates Spatial Memory Impairment Induced by Chronic Cerebral Hypoperfusion. Neurochem Res 2020; 45:2631-2640. [PMID: 32797381 DOI: 10.1007/s11064-020-03110-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2020] [Revised: 08/03/2020] [Accepted: 08/08/2020] [Indexed: 12/16/2022]
Abstract
Tropisetron and Granisetorn are 5-HT3 antagonists with antiemetic effects. Tropisetron also has a partial agonistic effect on alpha-7 nicotinic acetylcholine receptors (α7 nAChRs). On the other hand, chronic cerebral hypoperfusion (CCH) attenuates cerebral blood flow and impairs cognitive functions. The goal of this study was to investigate the effect of Tropisetron and Granisetron on CCH-induced spatial memory impairment in rats. Forty-eight male Wistar rats were used in this study. 2-VO surgery was done to induce CCH and Radial Eight Arm Maz apparatus was used to evaluate spatial memory (working and reference memory). Tropisetron was injected intraperitoneally at the doses of 1 and 5 mg/kg, and Granisetron was injected intraperitoneally at the dose of 3 mg/kg. Dorsal hippocampal (CA1) neurons count, Interleukin 6 (IL-6) serum level, and serotonin-reuptake transporter (SERT) gene expression were also evaluated. The results showed, CCH impaired working and reference memory, increased IL-6 serum level, and decreased CA1 neurons and SERT expression. Tropisetron at the dose of 5 mg/kg restored all the effects of CCH. However, Granisetron did not restore CCH-induced memory impairment. Furthermore, Granisetron had no effect on IL-6. While, it increased SERT expression and CA1 neurons. In conclusion, Tropisetron but not Granisetron, ameliorated spatial memory impairment induced by CCH. We suggested conducting more detailed studies investigating the role of serotonergic system (5-HT3 receptors and serotonin transporters) and also α7 nAChRs in the effects of Tropisetron.
Collapse
Affiliation(s)
- Ashkan Divanbeigi
- Department of Cognitive Neuroscience, Institute for Cognitive Science Studies (ICSS), Tehran, Iran.,Scientific Research Committee, Functional Neurosurgery Research Center, Shohada Tajrish Comprehensive Neurosurgical Center of Excellence, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Mohammad Nasehi
- Cognitive and Neuroscience Research Center (CNRC), Amir-Almomenin Hospital, Tehran Medical Sciences, Islamic Azad University, P.O. Box 13145-784, Tehran, Iran.
| | - Salar Vaseghi
- Department of Cognitive Neuroscience, Institute for Cognitive Science Studies (ICSS), Tehran, Iran.,Cognitive and Neuroscience Research Center (CNRC), Amir-Almomenin Hospital, Tehran Medical Sciences, Islamic Azad University, P.O. Box 13145-784, Tehran, Iran
| | - Sepideh Amiri
- Shefa Neuroscience Research Center, Khatam Alanbia Hospital, Tehran, Iran
| | - Mohammad-Reza Zarrindast
- Department of Cognitive Neuroscience, Institute for Cognitive Science Studies (ICSS), Tehran, Iran.,Cognitive and Neuroscience Research Center (CNRC), Amir-Almomenin Hospital, Tehran Medical Sciences, Islamic Azad University, P.O. Box 13145-784, Tehran, Iran.,Department of Pharmacology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran.,Iranian National Center for Addiction Studies, Tehran University of Medical Sciences, Tehran, Iran
| |
Collapse
|
4
|
One-day tropisetron treatment improves cognitive deficits and P50 inhibition deficits in schizophrenia. Neuropsychopharmacology 2020; 45:1362-1368. [PMID: 32349117 PMCID: PMC7297960 DOI: 10.1038/s41386-020-0685-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/15/2020] [Revised: 04/17/2020] [Accepted: 04/20/2020] [Indexed: 11/08/2022]
Abstract
The core features of schizophrenia (SCZ) include cognitive deficits and impaired sensory gating represented by P50 inhibition deficits, which appear to be related to the α7 nicotinic acetylcholine receptor (nAChR). An agonist of nAChR receptor may improve these defects. This study aimed to investigate how administering multiple doses of tropisetron, a partial agonist of nAChR, for 1 day would affect cognitive deficits and P50 inhibition deficits in SCZ patients. We randomized 40 SCZ non-smokers into a double-blind clinical trial with four groups: placebo, 5 mg/d, 10 mg/d, and 20 mg/d of oral tropisetron. Their P50 ratios were all more than 0.5 and they took risperidone at 3-6 mg/day for at least a month before participating in the experiment. We measured the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) and P50 inhibition before and one day after treatment. After one day of treatment, the total RBANS scores of the 20 mg and 5 mg tropisetron groups, and the immediate memory of the 10 mg group were significantly higher than placebo group. The P50 ratio was smaller in the 5 mg and 10 mg groups than in the placebo group (both p < 0.05) after treatment. Furthermore, the improvement in RBANS total score was correlated with increased S1 latency (p < 0.05), and the increase in immediate memory score was correlated with decreased S2 amplitude. One day of treatment with tropisetron improved both cognitive and P50 inhibition deficits, suggesting that longer term treatment with α7 nAChR agonists for these deficits in SCZ may be promising.
Collapse
|
5
|
Terry AV, Callahan PM. α7 nicotinic acetylcholine receptors as therapeutic targets in schizophrenia: Update on animal and clinical studies and strategies for the future. Neuropharmacology 2020; 170:108053. [PMID: 32188568 DOI: 10.1016/j.neuropharm.2020.108053] [Citation(s) in RCA: 52] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2020] [Revised: 03/10/2020] [Accepted: 03/11/2020] [Indexed: 10/24/2022]
Abstract
Schizophrenia is a devastating mental illness and its effective treatment is among the most challenging issues in psychiatry. The symptoms of schizophrenia are heterogeneous ranging from positive symptoms (e.g., delusions, hallucinations) to negative symptoms (e.g., anhedonia, social withdrawal) to cognitive dysfunction. Antipsychotics are effective at ameliorating positive symptoms in some patients; however, they are not reliably effective at improving the negative symptoms or cognitive impairments. The inability to address the cognitive impairments is a particular concern since they have the greatest long-term impact on functional outcomes. While decades of research have been devoted to the development of pro-cognitive agents for schizophrenia, to date, no drug has been approved for clinical use. Converging behavioral, neurobiological, and genetic evidence led to the identification of the α7-nicotinic acetylcholine receptor (α7-nAChR) as a therapeutic target several years ago and there is now extensive preclinical evidence that α7-nAChR ligands have pro-cognitive effects and other properties that should be beneficial to schizophrenia patients. However, like the other pro-cognitive strategies, no α7-nAChR ligand has been approved for clinical use in schizophrenia thus far. In this review, several topics are discussed that may impact the success of α7-nAChR ligands as pro-cognitive agents for schizophrenia including the translational value of the animal models used, clinical trial design limitations, confounding effects of polypharmacy, dose-effect relationships, and chronic versus intermittent dosing considerations. Determining the most optimal pharmacologic strategy at α7-nAChRs: agonist, positive allosteric modulator, or potentially even receptor antagonist is also discussed. article is part of the special issue on 'Contemporary Advances in Nicotine Neuropharmacology'.
Collapse
Affiliation(s)
- Alvin V Terry
- Department of Pharmacology and Toxicology, Medical College of Georgia, Augusta University, Augusta, 30912, Georgia; Small Animal Behavior Core, Medical College of Georgia, Augusta University, Augusta, 30912, Georgia.
| | - Patrick M Callahan
- Department of Pharmacology and Toxicology, Medical College of Georgia, Augusta University, Augusta, 30912, Georgia; Small Animal Behavior Core, Medical College of Georgia, Augusta University, Augusta, 30912, Georgia
| |
Collapse
|
6
|
Fakhfouri G, Rahimian R, Dyhrfjeld-Johnsen J, Zirak MR, Beaulieu JM. 5-HT 3 Receptor Antagonists in Neurologic and Neuropsychiatric Disorders: The Iceberg Still Lies beneath the Surface. Pharmacol Rev 2019; 71:383-412. [PMID: 31243157 DOI: 10.1124/pr.118.015487] [Citation(s) in RCA: 58] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
5-HT3 receptor antagonists, first introduced to the market in the mid-1980s, are proven efficient agents to counteract chemotherapy-induced emesis. Nonetheless, recent investigations have shed light on unappreciated dimensions of this class of compounds in conditions with an immunoinflammatory component as well as in neurologic and psychiatric disorders. The promising findings from multiple studies have unveiled several beneficial effects of these compounds in multiple sclerosis, stroke, Alzheimer disease, and Parkinson disease. Reports continue to uncover important roles for 5-HT3 receptors in the physiopathology of neuropsychiatric disorders, including depression, anxiety, drug abuse, and schizophrenia. This review addresses the potential of 5-HT3 receptor antagonists in neurology- and neuropsychiatry-related disorders. The broad therapeutic window and high compliance observed with these agents position them as suitable prototypes for the development of novel pharmacotherapeutics with higher efficacy and fewer adverse effects.
Collapse
Affiliation(s)
- Gohar Fakhfouri
- Department of Psychiatry and Neuroscience, Faculty of Medicine, CERVO Brain Research Centre, Laval University, Quebec, Quebec, Canada (G.F., R.R.); Sensorion SA, Montpellier, France (J.D.-J.); Department of Pharmacodynamics and Toxicology, School of Pharmacy, Mashhad University of Medical Sciences, Mashhad, Iran (M.R.Z.); and Department of Pharmacology and Toxicology, University of Toronto, Toronto, Ontario, Canada (J.-M.B.)
| | - Reza Rahimian
- Department of Psychiatry and Neuroscience, Faculty of Medicine, CERVO Brain Research Centre, Laval University, Quebec, Quebec, Canada (G.F., R.R.); Sensorion SA, Montpellier, France (J.D.-J.); Department of Pharmacodynamics and Toxicology, School of Pharmacy, Mashhad University of Medical Sciences, Mashhad, Iran (M.R.Z.); and Department of Pharmacology and Toxicology, University of Toronto, Toronto, Ontario, Canada (J.-M.B.)
| | - Jonas Dyhrfjeld-Johnsen
- Department of Psychiatry and Neuroscience, Faculty of Medicine, CERVO Brain Research Centre, Laval University, Quebec, Quebec, Canada (G.F., R.R.); Sensorion SA, Montpellier, France (J.D.-J.); Department of Pharmacodynamics and Toxicology, School of Pharmacy, Mashhad University of Medical Sciences, Mashhad, Iran (M.R.Z.); and Department of Pharmacology and Toxicology, University of Toronto, Toronto, Ontario, Canada (J.-M.B.)
| | - Mohammad Reza Zirak
- Department of Psychiatry and Neuroscience, Faculty of Medicine, CERVO Brain Research Centre, Laval University, Quebec, Quebec, Canada (G.F., R.R.); Sensorion SA, Montpellier, France (J.D.-J.); Department of Pharmacodynamics and Toxicology, School of Pharmacy, Mashhad University of Medical Sciences, Mashhad, Iran (M.R.Z.); and Department of Pharmacology and Toxicology, University of Toronto, Toronto, Ontario, Canada (J.-M.B.)
| | - Jean-Martin Beaulieu
- Department of Psychiatry and Neuroscience, Faculty of Medicine, CERVO Brain Research Centre, Laval University, Quebec, Quebec, Canada (G.F., R.R.); Sensorion SA, Montpellier, France (J.D.-J.); Department of Pharmacodynamics and Toxicology, School of Pharmacy, Mashhad University of Medical Sciences, Mashhad, Iran (M.R.Z.); and Department of Pharmacology and Toxicology, University of Toronto, Toronto, Ontario, Canada (J.-M.B.)
| |
Collapse
|
7
|
Poddar I, Callahan PM, Hernandez CM, Yang X, Bartlett MG, Terry AV. Tropisetron enhances recognition memory in rats chronically treated with risperidone or quetiapine. Biochem Pharmacol 2017; 151:180-187. [PMID: 29175423 DOI: 10.1016/j.bcp.2017.11.017] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2017] [Accepted: 11/22/2017] [Indexed: 12/16/2022]
Abstract
While impairments of cognition in schizophrenia have the greatest impact on long-term functional outcome, the currently prescribed treatments, antipsychotic drugs (APDs), do not effectively improve cognition. Moreover, while more than 20 years have been devoted to the development of new drugs to treat cognitive deficits in schizophrenia, none have been approved to date. One area that has not been given proper attention at the preclinical or clinical stage of drug development is the chronic medication history of the test subject. Hence, very little is known about how chronic treatment with drugs that affect multiple receptors like APDs influence the response to a potential pro-cognitive agent. Therefore, the purpose of this study was to evaluate the α7 nicotinic acetylcholine receptor (α7 nAChR) partial agonist, tropisetron in rats chronically treated with APDs with distinct pharmacological profiles. Rats were treated orally with either risperidone (2.5 mg/kg/day) or quetiapine (25.0 mg/kg/day) for 30 or 90 days and then an acute injection of vehicle or tropisetron (3.0 mg/kg) was administered before training in a novel object recognition (NOR) task. After a 48 h delay (when recollection of the familiar object was impaired in vehicle-treated animals) neither 30 nor 90 days of risperidone or quetiapine treatment improved NOR performance. In contrast, tropisetron markedly improved NOR performance in rats treated with either APD for 30 or 90 days. These animal data reinforce the argument that two commonly prescribed APDs are not pro-cognitive agents and that α7 nAChR ligands like tropisetron have potential as adjunctive treatments in schizophrenia.
Collapse
Affiliation(s)
- Indrani Poddar
- Department of Pharmacology and Toxicology, Medical College of Georgia, Augusta University, Augusta, GA 30912, Georgia
| | - Patrick M Callahan
- Department of Pharmacology and Toxicology, Medical College of Georgia, Augusta University, Augusta, GA 30912, Georgia; Small Animal Behavior Core, Augusta University, Augusta, GA 30912, Georgia
| | - Caterina M Hernandez
- Department of Pharmacology and Toxicology, Medical College of Georgia, Augusta University, Augusta, GA 30912, Georgia; Small Animal Behavior Core, Augusta University, Augusta, GA 30912, Georgia
| | - Xiangkun Yang
- Department of Pharmaceutical and Biomedical Sciences, University of Georgia College of Pharmacy, Athens, GA 30607, Georgia
| | - Michael G Bartlett
- Department of Pharmaceutical and Biomedical Sciences, University of Georgia College of Pharmacy, Athens, GA 30607, Georgia
| | - Alvin V Terry
- Department of Pharmacology and Toxicology, Medical College of Georgia, Augusta University, Augusta, GA 30912, Georgia; Small Animal Behavior Core, Augusta University, Augusta, GA 30912, Georgia.
| |
Collapse
|
8
|
Callahan PM, Bertrand D, Bertrand S, Plagenhoef MR, Terry AV. Tropisetron sensitizes α7 containing nicotinic receptors to low levels of acetylcholine in vitro and improves memory-related task performance in young and aged animals. Neuropharmacology 2017; 117:422-433. [PMID: 28259598 DOI: 10.1016/j.neuropharm.2017.02.025] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2016] [Revised: 02/06/2017] [Accepted: 02/25/2017] [Indexed: 01/02/2023]
Abstract
Tropisetron, a 5-HT3 receptor antagonist commonly prescribed for chemotherapy-induced nausea and vomiting also exhibits high affinity, partial agonist activity at α7 nicotinic acetylcholine receptors (α7 nAChRs). α7 nAChRs are considered viable therapeutic targets for neuropsychiatric disorders such as Alzheimer's disease (AD). Here we further explored the nAChR pharmacology of tropisetron to include the homomeric α7 nAChR and recently characterized heteromeric α7β2 nAChR (1:10 ratio) and we evaluated its cognitive effects in young and aged animals. Electrophysiological studies on human nAChRs expressed in Xenopus oocytes confirmed the partial agonist activity of tropisetron at α7 nAChRs (EC50 ∼2.4 μM) with a similar effect at α7β2 nAChRs (EC50 ∼1.5 μM). Moreover, currents evoked by irregular pulses of acetylcholine (40 μM) at α7 and α7β2 nAChRs were enhanced during sustained exposure to low concentrations of tropisetron (10 and 30 nM) indicative of a "priming" or co-agonist effect. Tropisetron (0.1-10 mg/kg) improved novel object recognition performance in young Sprague-Dawley rats and in aged Fischer rats. In aged male and female rhesus monkeys, tropisetron (0.03-1 mg/kg) produced a 17% increase from baseline levels in delayed match to sample long delay accuracy while combination of non-effective doses of donepezil (0.1 mg/kg) and tropisetron (0.03 and 0.1 mg/kg) produced a 24% change in accuracy. Collectively, these animal experiments indicate that tropisetron enhances cognition and has the ability to improve the effective dose range of currently prescribed AD therapy (donepezil). Moreover, these effects may be explained by tropisetron's ability to sensitize α7 containing nAChRs to low levels of acetylcholine.
Collapse
Affiliation(s)
- Patrick M Callahan
- Department of Pharmacology and Toxicology, Augusta University, Augusta, GA 30912, United States.
| | - Daniel Bertrand
- HiQScreen Sàrl, 6, rte de Compois, 1222 Vésenaz, Geneva, Switzerland
| | - Sonia Bertrand
- HiQScreen Sàrl, 6, rte de Compois, 1222 Vésenaz, Geneva, Switzerland
| | - Marc R Plagenhoef
- Department of Pharmacology and Toxicology, Augusta University, Augusta, GA 30912, United States
| | - Alvin V Terry
- Department of Pharmacology and Toxicology, Augusta University, Augusta, GA 30912, United States
| |
Collapse
|
9
|
The Novel, Nicotinic Alpha7 Receptor Partial Agonist, BMS-933043, Improves Cognition and Sensory Processing in Preclinical Models of Schizophrenia. PLoS One 2016; 11:e0159996. [PMID: 27467081 PMCID: PMC4965148 DOI: 10.1371/journal.pone.0159996] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2016] [Accepted: 07/12/2016] [Indexed: 01/01/2023] Open
Abstract
The development of alpha7 nicotinic acetylcholine receptor agonists is considered a promising approach for the treatment of cognitive symptoms in schizophrenia patients. In the present studies we characterized the novel agent, (2R)-N-(6-(1H-imidazol-1-yl)-4-pyrimidinyl)-4'H-spiro[4-azabicyclo[2.2.2]octane-2,5'-[1,3]oxazol]-2'-amine (BMS-933043), in vitro and in rodent models of schizophrenia-like deficits in cognition and sensory processing. BMS-933043 showed potent binding affinity to native rat (Ki = 3.3 nM) and recombinant human alpha7 nicotinic acetylcholine receptors (Ki = 8.1 nM) and agonist activity in a calcium fluorescence assay (EC50 = 23.4 nM) and whole cell voltage clamp electrophysiology (EC50 = 0.14 micromolar (rat) and 0.29 micromolar (human)). BMS-933043 exhibited a partial agonist profile relative to acetylcholine; the relative efficacy for net charge crossing the cell membrane was 67% and 78% at rat and human alpha7 nicotinic acetylcholine receptors respectively. BMS-933043 showed no agonist or antagonist activity at other nicotinic acetylcholine receptor subtypes and was at least 300 fold weaker at binding to and antagonizing human 5-HT3A receptors (Ki = 2,451 nM; IC50 = 8,066 nM). BMS-933043 treatment i) improved 24 hour novel object recognition memory in mice (0.1-10 mg/kg, sc), ii) reversed MK-801-induced deficits in Y maze performance in mice (1-10 mg/kg, sc) and set shift performance in rats (1-10 mg/kg, po) and iii) reduced the number of trials required to complete the extradimensional shift discrimination in neonatal PCP treated rats performing the intra-dimensional/extradimensional set shifting task (0.1-3 mg/kg, po). BMS-933043 also improved auditory gating (0.56-3 mg/kg, sc) and mismatch negativity (0.03-3 mg/kg, sc) in rats treated with S(+)ketamine or neonatal phencyclidine respectively. Given this favorable preclinical profile BMS-933043 was selected for further development to support clinical evaluation in humans.
Collapse
|
10
|
Tregellas JR, Smucny J, Legget KT, Stevens KE. Effects of a ketogenic diet on auditory gating in DBA/2 mice: A proof-of-concept study. Schizophr Res 2015; 169:351-354. [PMID: 26453015 PMCID: PMC4827327 DOI: 10.1016/j.schres.2015.09.022] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/18/2015] [Revised: 09/18/2015] [Accepted: 09/21/2015] [Indexed: 11/20/2022]
Abstract
Although the ketogenic diet has shown promise in a pilot study and case report in schizophrenia, its effects in animal models of hypothesized disease mechanisms are unknown. This study examined effects of treatment with the ketogenic diet on hippocampal P20/N40 gating in DBA/2 mice, a translational endophenotype that mirrors inhibitory deficits in P50 sensory gating in schizophrenia patients. As expected, the diet increased blood ketone levels. Animals with the highest ketone levels showed the lowest P20/N40 gating ratios. These preliminary results suggest that the ketogenic diet may effectively target sensory gating deficits and is a promising area for additional research in schizophrenia.
Collapse
Affiliation(s)
- Jason R Tregellas
- Research Service, Denver VA Medical Center, Denver, CO, USA; Neuroscience Program, University of Colorado Anschutz Medical Campus, Aurora, CO, USA; Department of Psychiatry, University of Colorado Anschutz Medical Campus, Aurora, CO, USA.
| | - Jason Smucny
- Neuroscience Program, University of Colorado Anschutz Medical Campus, Aurora, CO, USA; Department of Psychiatry, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - Kristina T Legget
- Neuroscience Program, University of Colorado Anschutz Medical Campus, Aurora, CO, USA; Department of Psychiatry, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - Karen E Stevens
- Department of Psychiatry, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| |
Collapse
|
11
|
Bertrand D, Lee CHL, Flood D, Marger F, Donnelly-Roberts D. Therapeutic Potential of α7 Nicotinic Acetylcholine Receptors. Pharmacol Rev 2015; 67:1025-73. [DOI: 10.1124/pr.113.008581] [Citation(s) in RCA: 108] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
|
12
|
Nicotinic ligands as multifunctional agents for the treatment of neuropsychiatric disorders. Biochem Pharmacol 2015; 97:388-398. [PMID: 26231940 DOI: 10.1016/j.bcp.2015.07.027] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2015] [Accepted: 07/24/2015] [Indexed: 02/08/2023]
Abstract
The challenges associated with developing more effective treatments for neurologic and psychiatric illness such as Alzheimer's disease and schizophrenia are considerable. Both the symptoms and the pathophysiology of these conditions are complex and poorly understood and the clinical presentations across different patients can be very heterogeneous. Moreover, it has become apparent that the reductionist approach to drug discovery for these illnesses that has dominated the field for decades (i.e., the development of highly selective compounds or other treatment modalities focused on a very specific pathophysiologic target) has not been widely successful. Accordingly, a variety of new strategies have emerged including the development of "multitarget-directed ligands" (MTDLs), the development and/or identification of compounds that exhibit "multifunctional" activity (e.g., pro-cognitive plus neuroprotective, pro-cognitive plus antipsychotic activity), "repurposing" strategies for existing compounds that have other clinical indications, and novel "adjunctive" treatment strategies that might enhance the efficacy of the currently available treatments. Interestingly, a variety of ligands at nicotinic acetylcholine receptors (nAChRs) appear to have the potential to fulfill one or more of these desirable properties (i.e., multifunctional, repurposing, or adjunctive treatment potential). The purpose of this review (while not all-inclusive) is to provide an overview of a variety of nAChR ligands that demonstrate potential in these categories, particularly, "multifunctional" properties. Due to their densities in the mammalian brain and the amount of literature available, the review will focus on ligands of the high affinity α4β2 nAChR and the low affinity α7 nAChR.
Collapse
|
13
|
Smucny J, Stevens KE, Olincy A, Tregellas JR. Translational utility of rodent hippocampal auditory gating in schizophrenia research: a review and evaluation. Transl Psychiatry 2015; 5:e587. [PMID: 26101850 PMCID: PMC4490287 DOI: 10.1038/tp.2015.77] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/09/2015] [Revised: 04/14/2015] [Accepted: 05/04/2015] [Indexed: 01/15/2023] Open
Abstract
Impaired gating of the auditory evoked P50 potential is one of the most pharmacologically well-characterized features of schizophrenia. This deficit is most commonly modeled in rodents by implanted electrode recordings from the hippocampus of the rodent analog of the P50, the P20-N40. The validity and effectiveness of this tool, however, has not been systematically reviewed. Here, we summarize findings from studies that have examined the effects of pharmacologic modulation on gating of the rodent hippocampal P20-N40 and the human P50. We show that drug effects on the P20-N40 are highly predictive of human effects across similar dose ranges. Furthermore, mental status (for example, anesthetized vs alert) does not appear to diminish the predictive capacity of these recordings. We then discuss hypothesized neuropharmacologic mechanisms that may underlie gating effects for each drug studied. Overall, this review supports continued use of hippocampal P20-N40 gating as a translational tool for schizophrenia research.
Collapse
Affiliation(s)
- J Smucny
- Neuroscience Program, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
- Research Service, Denver VA Medical Center, Denver, CO, USA
- Department of Psychiatry, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - K E Stevens
- Department of Psychiatry, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - A Olincy
- Research Service, Denver VA Medical Center, Denver, CO, USA
- Department of Psychiatry, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - J R Tregellas
- Neuroscience Program, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
- Research Service, Denver VA Medical Center, Denver, CO, USA
- Department of Psychiatry, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| |
Collapse
|
14
|
Stevens KE, Zheng L, Floyd KL, Stitzel JA. Maximizing the effect of an α7 nicotinic receptor PAM in a mouse model of schizophrenia-like sensory inhibition deficits. Brain Res 2015; 1611:8-17. [PMID: 25744161 DOI: 10.1016/j.brainres.2015.02.044] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2014] [Revised: 02/20/2015] [Accepted: 02/21/2015] [Indexed: 12/30/2022]
Abstract
Positive allosteric modulators (PAMs) for the α7 nicotinic receptor hold promise for the treatment of sensory inhibition deficits observed in schizophrenia patients. Studies of these compounds in the DBA/2 mouse, which models the schizophrenia-related deficit in sensory inhibition, have shown PAMs to be effective in improving the deficit. However, the first published clinical trial of a PAM for both sensory inhibition deficits and related cognitive difficulties failed, casting a shadow on this therapeutic approach. The present study used both DBA/2 mice, and C3H Chrna7 heterozygote mice to assess the ability of the α7 PAM, PNU-120596, to improve sensory inhibition. Both of these strains of mice have reduced hippocampal α7 nicotinic receptor numbers and deficient sensory inhibition similar to schizophrenia patients. Low doses of PNU-120596 (1 or 3.33mg/kg) were effective in the DBA/2 mouse but not the C3H Chrna7 heterozygote mouse. Moderate doses of the selective α7 nicotinic receptor agonist, choline chloride (10 or 33mg/kg), were also ineffective in improving sensory inhibition in the C3H Chrna7 heterozygote mouse. However, combining the lowest doses of both PNU-120596 and choline chloride in this mouse model did improve sensory inhibition. We propose here that the difference in efficacy of PNU-120596 between the 2 mouse strains is driven by differences in hippocampal α7 nicotinic receptor numbers, such that C3H Chrna7 heterozygote mice require additional direct stimulation of the α7 receptors. These data may have implications for further clinical testing of putative α7 nicotinic receptor PAMs.
Collapse
Affiliation(s)
- Karen E Stevens
- Department of Psychiatry, University of Colorado Denver, Anschutz Medical Campus, Aurora, CO, USA.
| | - Lijun Zheng
- Department of Psychiatry, University of Colorado Denver, Anschutz Medical Campus, Aurora, CO, USA
| | - Kirsten L Floyd
- Department of Psychiatry, University of Colorado Denver, Anschutz Medical Campus, Aurora, CO, USA
| | - Jerry A Stitzel
- Institute for Behavioral Genetics, University of Colorado, Boulder, Boulder, CO, USA
| |
Collapse
|
15
|
Hashimoto K. Targeting of α7 Nicotinic Acetylcholine Receptors in the Treatment of Schizophrenia and the Use of Auditory Sensory Gating as a Translational Biomarker. Curr Pharm Des 2015; 21:3797-806. [PMID: 26044974 PMCID: PMC5024727 DOI: 10.2174/1381612821666150605111345] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2015] [Accepted: 06/04/2015] [Indexed: 11/22/2022]
Abstract
Accumulating evidence suggests that the α7 subtype of nicotinic acetylcholine receptors (nAChRs) plays a key role in inflammatory processes, thought to be involved in the pathophysiology of neuropsychiatric diseases, such as schizophrenia and Alzheimer's disease. Preclinical and clinical studies showed that the diminished suppression of P50 auditory evoked potentials in patients with schizophrenia may be associated with a decreased density of α7 nAChRs in the brain. This points to a role for auditory sensory gating (P50) as a translational biomarker. A number of agonists and positive allosteric modulators (PAMs) for α7 nAChR promoted beneficial effects in animal models with sensory gating and cognitive deficits. Additionally, several clinical studies showed that α7 nAChR agonists could improve suppression in auditory P50 evoked potentials, as well as cognitive deficits, and negative symptoms in patients with schizophrenia. Taken together, α7 nAChR presents as an extremely attractive therapeutic target for schizophrenia. In this article, the author discusses recent findings on α7 nAChR agonists such as DMXB-A, RG3487, TC-5619, tropisetron, EVP-6124 (encenicline), ABT-126, AQW051 and α7 nAChR PAMs such as JNJ-39393406, PNU- 120596 and AVL-3288 (also known as UCI-4083), and their potential as therapeutic drugs for neuropsychiatric diseases, such as schizophrenia.
Collapse
Affiliation(s)
- Kenji Hashimoto
- Division of Clinical Neuroscience, Chiba University Center for Forensic, Mental Health, 1-8-1 Inohana, Chiba 260-8670, Japan.
| |
Collapse
|
16
|
Romero-Pimentel AL, Vázquez-Roque RA, Camacho-Abrego I, Hoffman KL, Linares P, Flores G, Manjarrez E. Histological correlates of N40 auditory evoked potentials in adult rats after neonatal ventral hippocampal lesion: animal model of schizophrenia. Schizophr Res 2014; 159:450-7. [PMID: 25261883 DOI: 10.1016/j.schres.2014.09.009] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/09/2014] [Revised: 08/28/2014] [Accepted: 09/04/2014] [Indexed: 11/26/2022]
Abstract
The neonatal ventral hippocampal lesion (NVHL) is an established neurodevelopmental rat model of schizophrenia. Rats with NVHL exhibit several behavioral, molecular and physiological abnormalities that are similar to those found in schizophrenics. Schizophrenia is a severe psychiatric illness characterized by profound disturbances of mental functions including neurophysiological deficits in brain information processing. These deficits can be assessed by auditory evoked potentials (AEPs), where schizophrenics exhibit abnormalities in amplitude, duration and latency of such AEPs. The aim of the present study was to compare the density of cells in the temporal cerebral cortex and the N40-AEP of adult NVHL rats versus adult sham rats. We found that rats with NVHL exhibit significant lower amplitude of the N40-AEP and a significant lower number of cells in bilateral regions of the temporal cerebral cortex compared to sham rats. Because the AEP recordings were obtained from anesthetized rats, we suggest that NVHL leads to inappropriate innervation in thalamic-cortical pathways in the adult rat, leading to altered function of cortical networks involved in processing of primary auditory information.
Collapse
Affiliation(s)
- A L Romero-Pimentel
- Centro de Investigación en Reproducción Animal (CIRA), Universidad Autónoma de Tlaxcala-CINVESTAV, Tlaxcala, CP 90070, México; Instituto de Fisiología, Benemérita Universidad Autónoma de Puebla, 14 Sur 6301, Col. San Manuel, Puebla, Puebla, CP 72570, México
| | - R A Vázquez-Roque
- Instituto de Fisiología, Benemérita Universidad Autónoma de Puebla, 14 Sur 6301, Col. San Manuel, Puebla, Puebla, CP 72570, México
| | - I Camacho-Abrego
- Instituto de Fisiología, Benemérita Universidad Autónoma de Puebla, 14 Sur 6301, Col. San Manuel, Puebla, Puebla, CP 72570, México
| | - K L Hoffman
- Centro de Investigación en Reproducción Animal (CIRA), Universidad Autónoma de Tlaxcala-CINVESTAV, Tlaxcala, CP 90070, México
| | - P Linares
- Instituto de Fisiología, Benemérita Universidad Autónoma de Puebla, 14 Sur 6301, Col. San Manuel, Puebla, Puebla, CP 72570, México
| | - G Flores
- Instituto de Fisiología, Benemérita Universidad Autónoma de Puebla, 14 Sur 6301, Col. San Manuel, Puebla, Puebla, CP 72570, México.
| | - E Manjarrez
- Instituto de Fisiología, Benemérita Universidad Autónoma de Puebla, 14 Sur 6301, Col. San Manuel, Puebla, Puebla, CP 72570, México.
| |
Collapse
|
17
|
Callahan PM, Terry AV, Tehim A. Effects of the nicotinic α7 receptor partial agonist GTS-21 on NMDA-glutamatergic receptor related deficits in sensorimotor gating and recognition memory in rats. Psychopharmacology (Berl) 2014; 231:3695-706. [PMID: 24595504 PMCID: PMC4748388 DOI: 10.1007/s00213-014-3509-2] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/15/2013] [Accepted: 02/11/2014] [Indexed: 12/11/2022]
Abstract
RATIONALE Disturbances in information processing and cognitive function are key features of schizophrenia. Nicotinic α7 acetylcholine receptors (α7-nAChR) are involved in sensory gating and cognition, thereby representing a viable therapeutic strategy. OBJECTIVES AND METHODS We investigated the effects of GTS-21, an α7-nAChR partial agonist, on prepulse inhibition (PPI) of acoustic startle in two pharmacologic impairment models in Wistar male rats: NMDA-glutamate receptor antagonism by MK-801 and dopamine receptor agonism by apomorphine. The cognitive effects of GTS-21 were assessed using the object recognition task (ORT) at short (3 h) and long (48 h) delays in Sprague-Dawley male rats. Pharmacological specificity was assessed by methyllycaconitine (MLA) coadministration with GTS-21. RESULTS In the PPI task, GTS-21 (1-10 mg/kg) alone did not alter the PPI response or startle amplitude. Coadministration of GTS-21 with MK-801 (0.1 mg/kg) or apomorphine (0.5 mg/kg) abolished the pharmacologic-induced PPI impairment as did the antipsychotics clozapine (5.0 mg/kg) and haloperidol (0.3 mg/kg). MK-801 alone increased startle amplitude which was blocked by GTS-21. In the ORT, GTS-21 (0.1-10 mg/kg) reversed the MK-801 (0.08 mg/kg)-induced memory deficit at the 3 h delay and enhanced memory at the 48 h delay, an effect abolished by MLA (0.313-5 mg/kg). CONCLUSIONS The results extend our preclinical pharmacological understanding of GTS-21 to include the ability of GTS-21 to modulate NMDA-glutamate receptor function, in vivo. Given the role of NMDA-glutamate receptor involvement in schizophrenia, α7-nAChR agonists may represent a novel treatment strategy for the pathophysiological deficits of schizophrenia and other psychiatric disorders.
Collapse
Affiliation(s)
- Patrick M Callahan
- Department of Pharmacology and Toxicology, Small Animal Behavior Core, Georgia Regents University, Augusta, GA, 30912, USA,
| | | | | |
Collapse
|
18
|
Stevens KE, Choo KS, Stitzel JA, Marks MJ, Adams CE. Long-term improvements in sensory inhibition with gestational choline supplementation linked to α7 nicotinic receptors through studies in Chrna7 null mutation mice. Brain Res 2014; 1552:26-33. [PMID: 24462939 DOI: 10.1016/j.brainres.2014.01.022] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2013] [Revised: 11/18/2013] [Accepted: 01/15/2014] [Indexed: 11/26/2022]
Abstract
Perinatal choline supplementation has produced several benefits in rodent models, from improved learning and memory to protection from the behavioral effects of fetal alcohol exposure. We have shown that supplemented choline through gestation and lactation produces long-term improvement in deficient sensory inhibition in DBA/2 mice which models a similar deficit in schizophrenia patients. The present study extends that research by feeding normal or supplemented choline diets to DBA/2 mice carrying the null mutation for the α7 nicotinic receptor gene (Chrna7). DBA/2 mice heterozygotic for Chrna7 were bred together. Dams were placed on supplemented (5 gm/kg diet) or normal (1.1 gm/kg diet) choline at mating and remained on the specific diet until offspring weaning. Thereafter, offspring were fed standard rodent chow. Adult offspring were assessed for sensory inhibition. Brains were obtained to ascertain hippocampal α7 nicotinic receptor levels. Choline-supplemented mice heterozygotic or null-mutant for Chrna7 failed to show improvement in sensory inhibition. Only wildtype choline-supplemented mice showed improvement with the effect solely through a decrease in test amplitude. This supports the hypothesis that gestational-choline supplementation is acting through the α7 nicotinic receptor to improve sensory inhibition. Although there was a significant gene-dose-related change in hippocampal α7 receptor numbers, binding studies did not reveal any choline-dose-related change in binding in any hippocampal region, the interaction being driven by a significant genotype main effect (wildtype>heterozygote>null mutant). These data parallel a human study wherein the offspring of pregnant women receiving choline supplementation during gestation, showed better sensory inhibition than offspring of women on placebo.
Collapse
Affiliation(s)
- Karen E Stevens
- Medical Research Service, Veterans Affairs Medical Center, Denver, CO, USA; Department of Psychiatry, University of Colorado, Anchutz Medical Campus, 12800 East 19th Avenue, Aurora, CO, USA.
| | - Kevin S Choo
- Medical Research Service, Veterans Affairs Medical Center, Denver, CO, USA
| | - Jerry A Stitzel
- Institute for Behavioral Genetics, University of Colorado, Boulder, CO, USA
| | - Michael J Marks
- Institute for Behavioral Genetics, University of Colorado, Boulder, CO, USA
| | - Catherine E Adams
- Medical Research Service, Veterans Affairs Medical Center, Denver, CO, USA; Department of Psychiatry, University of Colorado, Anchutz Medical Campus, 12800 East 19th Avenue, Aurora, CO, USA
| |
Collapse
|
19
|
Smucny J, Stevens KE, Tregellas JR. Acute administration of Δ⁹ tetrahydrocannabinol does not prevent enhancement of sensory gating by clozapine in DBA/2 mice. Pharmacol Biochem Behav 2014; 118:22-9. [PMID: 24418217 DOI: 10.1016/j.pbb.2014.01.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/20/2013] [Revised: 12/19/2013] [Accepted: 01/03/2014] [Indexed: 11/29/2022]
Abstract
Despite high rates of marijuana abuse in schizophrenia, the physiological interactions between tetrahydrocannabinol (THC) and antipsychotic medications are poorly understood. A well-characterized feature of schizophrenia is poor gating of the P50 auditory-evoked potential. This feature has been translationally modeled by the DBA/2 mouse, which exhibits poor suppression of the P20-N40 AEP, the rodent analog of the human P50. Previous work has demonstrated that this deficit is reversed by the antipsychotic clozapine. It is unknown, however, if this effect is altered by THC administration. Using a conditioning-testing paradigm with paired auditory stimuli, the effects of clozapine and dronabinol (a pharmaceutical THC formulation) on inhibitory P20-N40 AEP processing were assessed from in vivo hippocampal CA3 recordings in anesthetized DBA/2 mice. The effects of clozapine (0.33 mg/kg) and dronabinol (10 mg/kg) were assessed alone and in combination (0.33, 1 or 1.83 mg/kg clozapine with 10mg/kg dronabinol). Improved P20-N40 AEP gating was observed after acute administration of 0.33 mg/kg clozapine. Co-injection of 0.33 mg/kg clozapine and 10 mg/kg THC, however, did not improve gating relative to baseline. This effect was overcome by higher doses of clozapine (1 and 1.83 mg/kg), as these doses improved gating relative to baseline in the presence of 10 mg/kg THC. 10 mg/kg THC alone did not affect gating. In conclusion, THC does not prevent improvement of P20-N40 gating by clozapine.
Collapse
Affiliation(s)
- Jason Smucny
- Neuroscience Program, University of Colorado Anschutz Medical Campus, Aurora, CO, USA; Research Service, Denver VA Medical Center, Denver, CO, USA; Department of Psychiatry, University of Colorado Anschutz Medical Campus, Aurora, CO, USA.
| | - Karen E Stevens
- Research Service, Denver VA Medical Center, Denver, CO, USA; Department of Psychiatry, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - Jason R Tregellas
- Neuroscience Program, University of Colorado Anschutz Medical Campus, Aurora, CO, USA; Research Service, Denver VA Medical Center, Denver, CO, USA; Department of Psychiatry, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| |
Collapse
|
20
|
Cotinine impacts sensory processing in DBA/2 mice through changes in the conditioning amplitude. Pharmacol Biochem Behav 2013; 117:144-50. [PMID: 24374321 DOI: 10.1016/j.pbb.2013.12.005] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/24/2013] [Revised: 11/04/2013] [Accepted: 12/05/2013] [Indexed: 02/04/2023]
Abstract
Cotinine, a major metabolite of nicotine, has produced improved learning and memory in rodents and non-human primates and corrects apomorphine-induced loss of pre-pulse startle inhibition in rats. The present study assessed cotinine, both acute and chronic (7-day), in the sensory inhibition paradigm in DBA/2 mice. These mice spontaneously show a deficit in hippocampal sensory inhibition, as assessed by the P20-N40 EEG paradigm, which models the deficit observed in schizophrenia patients. Anesthetized DBA/2 mice were recorded in the CA3 region of hippocampus for inhibition of paired, identical auditory stimuli, then administered cotinine (0.33, 0.1, 0.33, 1.0 or 3.3 mg/kg SQ) and recorded for 90 min. At doses of 0.1, 0.33 and 1.0 mg/kg, there were significant increases in conditioning amplitude, with no changes in test amplitude or TC ratio. Blockade of α4β2 nicotinic receptors with central administration of DHΒE blocked the increase in the conditioning amplitude induced by the 1.0 mg/kg dose of cotinine, as did blockade of α7 nicotinic receptors with α-bungarotoxin. Daily injections of 0.33, 1.0 or 3.3 mg/kg for 7 days produced similar increases in the conditioning amplitude on the 7th day, but only at the 0.33 and 3.3 mg/kg doses. Determination of the "carry over" effect of the previous 6 daily doses of cotinine, prior to the 7th dose, showed that there was a significant increase in the conditioning amplitude as compared to the baseline data for mice receiving the equivalent acute dose. There were no significant effects on test amplitude or TC ratio for any of the chronic doses. These data suggest that cotinine modulates the conditioning amplitude in the sensory inhibition paradigm through the α4β2 nicotinic receptor and possibly also through the α7 nicotinic receptor, as well. However the data do not suggest that cotinine is a potential therapeutic for the treatment of sensory inhibition deficits in schizophrenia.
Collapse
|
21
|
Stevens KE, Zheng L, Abrams DJ. Intermittent versus continuous central administration of clozapine in DBA/2 mice, improvement in sensory inhibition deficits. Schizophr Res 2013; 149:121-6. [PMID: 23863771 DOI: 10.1016/j.schres.2013.06.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/19/2013] [Revised: 05/23/2013] [Accepted: 06/02/2013] [Indexed: 11/30/2022]
Abstract
Deficient sensory inhibition, the failure to inhibit responses to repeated stimuli, is a hallmark of schizophrenia, and is thought to be related to difficulties with attention and working memory. Sensory inhibition is assessed by comparing the auditory-evoked EEG responses to 2 closely-spaced identical stimuli. Normal individuals show suppressed response to the second stimulus while schizophrenia patients have responses of similar magnitude to both stimuli. This deficit has been linked to polymorphisms in the promoter for the α7 nicotinic receptor gene, resulting in reduced numbers of receptors on hippocampal interneurons. This deficit is modeled in DBA/2 mice which also show a polymorphism in the promoter for the α7 nicotinic receptor gene and reduced numbers of hippocampal α7 receptors. Systemic administration of clozapine, the most efficacious antipsychotic medication, improves sensory inhibition deficits in both schizophrenia patients and DBA/2 mice. We have previously shown that acute intracerebroventricular (ICV) injections of clozapine induced similar improvement in sensory inhibition in DBA/2 mice. Here we demonstrate the efficacy of chronic ICV clozapine administration in improving sensory inhibition in DBA2 mice. Mice received ICV vehicle, 3, 7.5, 15 or 30 μg of clozapine, either continuously or as a once-per-day injection. Mice were recorded on the 7th day of drug delivery. Both approaches produced improved sensory inhibition, but the daily bolus injection was effective at a lower dose (3 μg/day) than the continuous delivery (15 μg/day). The bolus injections also showed significant improvement up to 36 h post injection thus suggesting that this approach may be more efficacious.
Collapse
Affiliation(s)
- Karen E Stevens
- Medical Research Service, VA Medical Center, 1055 Clermont Street, Denver, CO 80220, USA.
| | | | | |
Collapse
|
22
|
A placebo-controlled study of tropisetron added to risperidone for the treatment of negative symptoms in chronic and stable schizophrenia. Psychopharmacology (Berl) 2013; 228:595-602. [PMID: 23515583 DOI: 10.1007/s00213-013-3064-2] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/27/2012] [Accepted: 03/04/2013] [Indexed: 10/27/2022]
Abstract
RATIONAL A growing body of evidence illustrates that 5-HT3 receptor antagonist drugs may be of benefit in the treatment of negative symptoms in schizophrenia. OBJECTIVE The objective of this study was to assess the efficacy and tolerability of tropisetron add-on to risperidone on negative symptoms in patients with chronic stable schizophrenia. METHODS In a double-blind, placebo-controlled 8-week trial, 40 patients with chronic schizophrenia who were stabilized on risperidone were randomized into tropisetron or placebo add-on groups. Psychotic symptoms were measured using the Positive and Negative Syndrome Scale (PANSS) every 2 weeks. Furthermore, extrapyramidal and depressive symptoms as well as side effects were assessed. The primary outcome measure was the difference in change from baseline of negative subscale scores between the two groups at week 8. RESULTS Tropisetron resulted in greater improvement of the total PANSS scores [F(1.860,70.699) = 37.366, p < 0.001] as well as negative scores [F(2.439,92.675) = 16.623, p < 0.001] and general psychopathology [F(1.767,67.158) = 4.602, p = 0.017], but not positive subscale scores [F(1.348, 51.218) = 0.048, p = 0.893] compared to placebo. In a multiple regression analysis controlling for positive, extrapyramidal, and depressive symptoms, treatment group (standardized β = -0.640) significantly predicted changes in primary negative symptoms. The side effect profile did not differ significantly between the two groups. CONCLUSION Tropisetron add-on to risperidone improves the primary negative symptoms of patients with chronic stable schizophrenia.
Collapse
|
23
|
Young JW, Geyer MA. Evaluating the role of the alpha-7 nicotinic acetylcholine receptor in the pathophysiology and treatment of schizophrenia. Biochem Pharmacol 2013; 86:1122-32. [PMID: 23856289 DOI: 10.1016/j.bcp.2013.06.031] [Citation(s) in RCA: 100] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2013] [Revised: 06/27/2013] [Accepted: 06/28/2013] [Indexed: 12/16/2022]
Abstract
The group of schizophrenia disorders affects approximately 1% of the population and has both genetic and environmental etiologies. Sufferers report various behavioral abnormalities including hallucinations and delusions (positive symptoms), reduced joy and amotivation (negative symptoms), plus inattention and poor learning (cognitive deficits). Despite the heterogeneous symptoms experienced, most patients smoke. The self-medication hypothesis posits that patients smoke to alleviate symptoms, consistent with evidence for nicotine-induced enhancement of cognition. While nicotine acts on multiple nicotinic acetylcholine receptors (nAChRs), the primary target of research is often the homomeric α7 nAChR. Given genetic linkages between schizophrenia and this receptor, its association with P50 sensory gating deficits, and its reduced expression in post-mortem brains, many have attempted to develop α7 nAChR ligands for treating schizophrenia. Recent evidence that ligands can be orthosteric agonists or positive allosteric modulators (PAMs) has revitalized the hope for treatment discovery. Herein, we present evidence regarding: (1) pathophysiological alterations of α7 nAChRs that might occur in patients; (2) mechanistic evidence for the normal action of α7 nAChRs; (3) preclinical studies using α7 nAChR orthosteric agonists and type I/II PAMs; and (4) where successful translational testing has occurred for particular compounds, detailing what is still required. We report that the accumulating evidence is positive, but that greater work is required using positron emission tomography to understand current alterations in α7 nAChR expression and their relationship to symptoms. Finally, cross-species behavioral tasks should be used more regularly to determine the predictive efficacy of treatments.
Collapse
Affiliation(s)
- Jared W Young
- Department of Psychiatry, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0804, United States; Research Service, San Diego Veteran's Affairs Hospital, 3350 La Jolla Drive, San Diego, CA 92037, United States.
| | | |
Collapse
|
24
|
Khodaie-Ardakani MR, Seddighi S, Modabbernia A, Rezaei F, Salehi B, Ashrafi M, Shams-Alizadeh N, Mohammad-Karimi M, Esfandiari GR, Hajiaghaee R, Akhondzadeh S. Granisetron as an add-on to risperidone for treatment of negative symptoms in patients with stable schizophrenia: randomized double-blind placebo-controlled study. J Psychiatr Res 2013; 47:472-8. [PMID: 23375406 DOI: 10.1016/j.jpsychires.2013.01.011] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/17/2012] [Revised: 11/28/2012] [Accepted: 01/14/2013] [Indexed: 11/26/2022]
Abstract
Some 5-HT3 antagonists such as ondansetron have shown beneficial effects on negative symptoms of patients with schizophrenia. We aimed to evaluate the efficacy of granisetron (another 5-HT3 antagonist) add-on therapy in the treatment of negative symptoms of patients with stable schizophrenia. In a randomized, double-blind, and placebo-controlled study, forty stable patients with schizophrenia (DSM-IV-TR), were randomized to either granisetron (1 mg twice daily) or placebo (twice daily) in addition to risperidone up to 6 mg/day for eight weeks. The patients were assessed using positive and negative syndrome scale (PANSS) and extrapyramidal symptom rating scale (ESRS) at baseline, week 4 and 8. Hamilton depression rating scale (HDRS) was used to assess depression at baseline and week 8. Thirty-eight patients completed the trial. Granisetron group showed a significantly greater improvement on negative subscale than the placebo group at endpoint [t(38) = 6.046, mean difference (±95% CI) = 3.2(1.8-3.7), P < 0.001]. The same effect was observed for total score [t(38) = 4.168, mean difference (95% CI) = 3.2(1.6-4.7), P < 0.001]. However the placebo and granisetron groups did not differ in their reduction of positive and general psychopathology symptoms scores. HDRS scores and its changes did not differ between the two groups. The ESRS score at week 4 was significantly lower in the granisetron than the placebo group while the two groups showed similar ESRS score at week 8. Frequency of other side effects was similar between the two groups. In summary, granisetron add-on can safely and effectively reduce the primary negative symptoms of patients with schizophrenia.
Collapse
|
25
|
Askari N, Moin M, Sanati M, Tajdini M, Hosseini SMR, Modabbernia A, Najand B, Salimi S, Tabrizi M, Ashrafi M, Hajiaghaee R, Akhondzadeh S. Granisetron adjunct to fluvoxamine for moderate to severe obsessive-compulsive disorder: a randomized, double-blind, placebo-controlled trial. CNS Drugs 2012; 26:883-92. [PMID: 22873680 DOI: 10.2165/11635850-000000000-00000] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
BACKGROUND Several small studies have shown beneficial effects of ondansetron, a serotonin 5-HT(3) receptor antagonist, in the treatment of obsessive-compulsive disorder (OCD). The efficacy of other 5-HT(3) receptor antagonists in patients with OCD is still unclear. Granisetron does not alter cytochrome P450 activity and might have a lower risk of drug interactions, a longer duration of action and a better tolerability profile than other 5-HT(3) receptor antagonists. OBJECTIVE The objective of this study was to assess the efficacy and tolerability of granisetron augmentation of fluvoxamine in patients with OCD. STUDY DESIGN This was a two-centre, randomized, double-blind, placebo-controlled, parallel-group study conducted from November 2011 to March 2012. STUDY SETTING The study setting was outpatient clinics of two large referral centres. PATIENTS Study participants were men and women, aged 18-60 years, who met the diagnostic criteria of OCD based on the DSM-IV-TR and who had a Yale-Brown Obsessive Compulsive Scale (Y-BOCS) score of at least 21. INTERVENTIONS Participants were randomly assigned to granisetron (Kytril(®); SmithKline Beecham, Philadelphia, PA, USA) 1 mg every 12 hours or placebo every 12 hours in addition to fluvoxamine for 8 weeks. MAIN OUTCOME MEASURE Patients were assessed using the Y-BOCS at baseline, second, fourth, sixth and eighth weeks. The primary outcome measure was the difference in the score change of Y-BOCS total score from baseline to week 8 between the two groups. We also compared changes in the obsession and compulsion subscales of the Y-BOCS, and frequencies of partial response (≥25% reduction in Y-BOCS score), complete response (≥35% reduction in Y-BOCS score) and remission (Y-BOCS score ≤16) between the two groups. RESULTS Of the 42 included patients, 39 (20 in the placebo group, 19 in the granisetron group) completed the study. Significant time X treatment interaction was observed for total Y-BOCS (F [2.097, 79.678] = 4.941, p = 0.009), obsession (F [2.337, 88.799] = 4.938, p = 0.006) and compulsion (F [2.050, 77.899] = 4.674, p = 0.012) subscales. By week 8, complete response and remission were achieved by 20 (100%) and 18 (90%) patients in the granisetron group and by 7 (35%) patients in the placebo group (p-value of Fisher's exact test <0.001, risk ratio (RR) [95% CI] = 3.857 [2.039, 7.297]). There was no significant difference in the tolerability between the two regimens. CONCLUSION Granisetron is an efficacious adjunct for the short-term treatment of patients with moderate to severe OCD and is well tolerated. CLINICAL TRIAL REGISTRATION NUMBER IRCT201202041556N32.
Collapse
Affiliation(s)
- Neda Askari
- Psychiatric Research Center, Roozbeh Hospital, Tehran University of Medical Sciences, Tehran, Iran
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
26
|
Radek RJ, Robb HM, Stevens KE, Gopalakrishnan M, Bitner RS. Effects of the novel α7 nicotinic acetylcholine receptor agonist ABT-107 on sensory gating in DBA/2 mice: pharmacodynamic characterization. J Pharmacol Exp Ther 2012; 343:736-45. [PMID: 22988063 DOI: 10.1124/jpet.112.197970] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Nicotinic acetylcholine receptor (nAChR) agonists improve sensory gating deficits in animal models and schizophrenic patients. The aim of this study was to determine whether the novel and selective α7 nAChR full agonist 5-(6-[(3R)-1-azabicyclo[2.2.2]oct-3-yloxy]pyridazin-3-yl)-1H-indole (ABT-107) improves sensory gating deficits in DBA/2 mice. Sensory gating was measured by recording hippocampal-evoked potential P20-N40 waves and determining gating test/conditioning (T/C) ratios in a paired auditory stimulus paradigm. ABT-107 at 0.1 μmol/kg (average plasma concentration of 1.1 ng/ml) significantly improved sensory gating by lowering T/C ratios during a 30-min period after administration in unanesthetized DBA/2 mice. ABT-107 at 1.0 μmol/kg was ineffective at 30 min after administration when average plasma levels were 13.5 ng/ml. However, the 1.0 μmol/kg dose was effective 180 min after administration when plasma concentration had fallen to 1.9 ng/ml. ABT-107 (0.1 μmol/kg) also improved sensory gating in anesthetized DBA/2 mice pretreated with α7 nAChR-desensitizing doses of nicotine (6.2 μmol/kg) or ABT-107 (0.1 μmol/kg) itself. Moreover, repeated b.i.d. dosing of ABT-107 (0.1 μmol/kg) was as efficacious as a single dose. The acute efficacy of ABT-107 (0.1 μmol/kg) was blocked by the nAChR antagonist methyllycaconitine, but not by the α4β2 nAChR antagonist dihydro-β-erythroidine. These studies demonstrate that ABT-107 improves sensory gating through the activation of nAChRs, and efficacy is sustained under conditions of repeated dosing or with prior nAChR activation with nicotine.
Collapse
Affiliation(s)
- Richard J Radek
- Global Pharmaceutical Research and Development, Abbott Laboratories, Abbott Park, IL 60064, USA.
| | | | | | | | | |
Collapse
|
27
|
Nicotine receptor subtype-specific effects on auditory evoked oscillations and potentials. PLoS One 2012; 7:e39775. [PMID: 22911690 PMCID: PMC3401200 DOI: 10.1371/journal.pone.0039775] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2012] [Accepted: 05/25/2012] [Indexed: 12/22/2022] Open
Abstract
Background Individuals with schizophrenia show increased smoking rates which may be due to a beneficial effect of nicotine on cognition and information processing. Decreased amplitude of the P50 and N100 auditory event-related potentials (ERPs) is observed in patients. Both measures show normalization following administration of nicotine. Recent studies identified an association between deficits in auditory evoked gamma oscillations and impaired information processing in schizophrenia, and there is evidence that nicotine normalizes gamma oscillations. Although the role of nicotine receptor subtypes in augmentation of ERPs has received some attention, less is known about how these receptor subtypes regulate the effect of nicotine on evoked gamma activity. Methodology/Principal Findings We examined the effects of nicotine, the α7 nicotine receptor antagonist methyllycaconitine (MLA) the α4β4/α4β2 nicotine receptor antagonist dihydro-beta-erythroidine (DHβE), and the α4β2 agonist AZD3480 on P20 and N40 amplitude as well as baseline and event-related gamma oscillations in mice, using electrodes in hippocampal CA3. Nicotine increased P20 amplitude, while DHβE blocked nicotine-induced enhancements in P20 amplitude. Conversely, MLA did not alter P20 amplitude either when presented alone or with nicotine. Administration of the α4β2 specific agonist AZD3480 did not alter any aspect of P20 response, suggesting that DHβE blocks the effects of nicotine through a non-α4β2 receptor specific mechanism. Nicotine and AZD3480 reduced N40 amplitude, which was blocked by both DHβE and MLA. Finally, nicotine significantly increased event-related gamma, as did AZD3480, while DHβE but not MLA blocked the effect of nicotine on event-related gamma. Conclusions/Significance These results support findings showing that nicotine-induced augmentation of P20 amplitude occurs via a DHβE sensitive mechanism, but suggests that this does not occur through activation of α4β2 receptors. Event-related gamma is strongly influenced by activation of α4β2, but not α7, receptor subtypes, while disruption of N40 amplitude requires the activation of multiple receptor subtypes.
Collapse
|
28
|
Hellier JL, Arevalo NL, Smith L, Xiong KN, Restrepo D. α7-Nicotinic acetylcholine receptor: role in early odor learning preference in mice. PLoS One 2012; 7:e35251. [PMID: 22514723 PMCID: PMC3325997 DOI: 10.1371/journal.pone.0035251] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2012] [Accepted: 03/14/2012] [Indexed: 11/19/2022] Open
Abstract
Recently, we have shown that mice with decreased expression of α7-nicotinic acetylcholine receptors (α7) in the olfactory bulb were associated with a deficit in odor discrimination compared to wild-type mice. However, it is unknown if mice with decreased α7-receptor expression also show a deficit in early odor learning preference (ELP), an enhanced behavioral response to odors with attractive value observed in rats. In this study, we modified ELP methods performed in rats and implemented similar conditions in mice. From post-natal days 5–18, wild-type mice were stroked simultaneously with an odor presentation (conditioned odor) for 90 s daily. Control mice were only stroked, exposed to odor, or neither. On the day of testing (P21), mice that were stroked in concert with a conditioned odor significantly investigated the conditioned odor compared to a novel odor, as observed similarly in rats. However, mice with a decrease in α7-receptor expression that were stroked during a conditioned odor did not show a behavioral response to that odorant. These results suggest that decreased α7-receptor expression has a role in associative learning, olfactory preference, and/or sensory processing deficits.
Collapse
Affiliation(s)
- Jennifer L Hellier
- Department of Cell and Developmental Biology, University of Colorado Anschutz Medical Campus, Aurora, Colorado, United States of America.
| | | | | | | | | |
Collapse
|
29
|
Ishikawa M, Sakata M, Toyohara J, Oda K, Ishii K, Wu J, Yoshida T, Iyo M, Ishiwata K, Hashimoto K. Occupancy of α7 Nicotinic Acetylcholine Receptors in the Brain by Tropisetron: A Positron Emission Tomography Study Using [(11)C]CHIBA-1001 in Healthy Human Subjects. CLINICAL PSYCHOPHARMACOLOGY AND NEUROSCIENCE 2011; 9:111-6. [PMID: 23430308 PMCID: PMC3569118 DOI: 10.9758/cpn.2011.9.3.111] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/13/2011] [Revised: 08/24/2011] [Accepted: 09/06/2011] [Indexed: 11/18/2022]
Abstract
OBJECTIVE Agonists of α7-nicotinic acetylcholine receptors (nAChRs) have been developed as potential therapeutic drugs for neuropsychiatric diseases such as schizophrenia and Alzheimer's disease. Positron emission tomography (PET) is a noninvasive brain imaging technique to measure receptor occupancy in the living human brain. Although much effort has been expended to create specific PET radioligands for α7-nAChRs in the brain, only 4-[(11)C]methylphenyl-1,4-diazabicyclo[3.2.2.]nonane-4-carboxylate ([(11)C]CHIBA-1001) is currently available for clinical studies. In contrast, two 5-hydroxytryptamine-3 (5-HT(3)) receptor antagonists, tropisetron and ondansetron, have been used to treat patients with chemotherapy-induced or postoperative nausea and vomiting. Furthermore, tropisetron, but not ondansetron, possesses high affinity for α7-nAChRs. In the present study, we evaluated the receptor occupancy in the human brain after a single oral administration of tropisetron and ondansetron using [(11)C]CHIBA-1001 and PET. METHODS Two serial dynamic PET scans using [(11)C]CHIBA-1001 in healthy non-smoking male subjects were performed before and after receiving an oral administration of these medications. RESULTS A single oral administration of tropisetron, but not ondansetron, decreased the total distribution volume of [(11)C]CHIBA-1001 in the human brain. CONCLUSION This study shows that tropisetron, but not ondansetron, could bind to α7-nAChRs in the human brain after a single oral administration. Therefore, [(11)C]CHIBA-1001 may be a useful PET radioligand to measure the occupancy of α7-nAChRs in the human brain.
Collapse
Affiliation(s)
- Masatomo Ishikawa
- Division of Clinical Neuroscience, Chiba University Center for Forensic Mental Health, Chiba, Japan
| | | | | | | | | | | | | | | | | | | |
Collapse
|
30
|
Wildeboer-Andrud KM, Stevens KE. The smoking cessation drug varenicline improves deficient P20-N40 inhibition in DBA/2 mice. Pharmacol Biochem Behav 2011; 100:17-24. [PMID: 21763340 PMCID: PMC3183147 DOI: 10.1016/j.pbb.2011.07.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/20/2010] [Revised: 06/30/2011] [Accepted: 07/02/2011] [Indexed: 11/29/2022]
Abstract
Varenicline, an FDA approved smoking cessation pharmacotherapy, is an α4β2* nicotinic acetylcholine receptor (nAChR) partial agonist and an α7* nAChR full agonist. Both subtypes of nAChR are involved in modulating auditory evoked responses in rodents. In DBA/2 mice, an inbred strain, auditory evoked responses to paired auditory stimuli fail to inhibit to the second stimulus. This mouse strain replicates the auditory evoked response inhibition deficit experienced by the majority of schizophrenia patients. In this current study, we examined the effects of five different doses of varenicline (0.06, 0.3, 0.6, 3 and 6mg/kg) on auditory evoked responses in anesthetized DBA/2 mice. We also administered α4β2* and α7* nAChR selective antagonists prior to varenicline administration to determine which nAChR subtypes mediate the effects of varenicline. Four of the five doses of varenicline produced improvements in auditory evoked response inhibition deficits. Selective blockade of either the α4β2* or α7* nAChR in competition with 0.6mg/kg varenicline prevented varenicline induced improvements. In competition with a higher dose of varenicline (3mg/kg) only blockade of the α4β2* nAChR prevented varenicline induced improvement in auditory evoked response inhibition. These data indicate the importance of α4β2* nAChRs and the potential involvement of the α7* subtype in varenicline's effects on auditory evoked responses in DBA/2 mice.
Collapse
|
31
|
Evidence for association of the non-duplicated region of CHRNA7 gene with bipolar disorder but not with Schizophrenia. Psychiatr Genet 2011; 20:289-97. [PMID: 20463630 DOI: 10.1097/ypg.0b013e32833a9b7a] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
OBJECTIVE Biological evidence in both human and animal studies suggests α7 neuronal nicotinic acetylcholine receptor subunit gene (CHRNA7) as a suitable functional candidate for genetic studies in psychiatric populations. This gene maps to chromosome 15q13-14, a major linkage hotspot for schizophrenia (SCH) and bipolar disorder (BD). In this study we examine the role of CHRNA7 in influencing the risk of SCH and BD. METHODS In the present investigation four SNPs of the non-duplicated region of CHRNA7 were genotyped: -86C/T variant, located in the 5'-upstream regulatory region; and three intronic polymorphisms (rs883473, rs6494223 and rs904952). Genetic analysis was performed on 510 patients diagnosed with SCH, 245 with BD and on 793 unrelated healthy controls. RESULTS SNP analysis suggested a significant difference in -86C/T allele (P=0.025) and genotype (P=0.03) frequencies between BD and control groups, although significance was lost after correction for multiple testing. Besides, the nucleotide change (T) in rs6494223 had a protective effect against BD [odds ratio (OR)=0.70 (0.57-0.87); P=0.001]. Genotype frequencies also showed significant association (P=0.001) [CT genotype OR=0.71 (0.5-0.96); TT genotype OR=0.47 (0.29-0.77)]. Haplotypic analysis revealed a positive association of the gene with BD (global-stat=24.18, P value=0.007) with a maximum effect in the region that covered introns 3 and 4. In contrast, no evidence of risk variants was found in the analysis of the SCH sample. CONCLUSION Our data support the non-duplicated region of CHRNA7 gene as a susceptibility region for BD but not for SCH. Further genotyping of this region may help to delimit the causal polymorphism.
Collapse
|
32
|
André JM, Leach PT, Gould TJ. Nicotine ameliorates NMDA receptor antagonist-induced deficits in contextual fear conditioning through high-affinity nicotinic acetylcholine receptors in the hippocampus. Neuropharmacology 2010; 60:617-25. [PMID: 21167848 DOI: 10.1016/j.neuropharm.2010.12.004] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2010] [Revised: 12/06/2010] [Accepted: 12/08/2010] [Indexed: 01/31/2023]
Abstract
NMDA glutamate receptors (NMDARs) and nicotinic acetylcholine receptors (nAChRs) are both involved in learning and synaptic plasticity. Increasing evidence suggests processes mediated by these receptors may interact to modulate learning; however, little is known about the neural substrates involved in these interactive processes. The present studies investigated the effects of nicotine on MK-801 hydrogen maleate (MK-801) and DL-2-Amino-5-phosphonovaleric acid (APV)-induced disruption of contextual fear conditioning in male C57BL/6J mice, using direct drug infusion and selective nAChR antagonists to define the brain regions and the nAChR subtypes involved. Mice treated with MK-801 showed a deficit in contextual fear conditioning that was ameliorated by nicotine. Direct drug infusion demonstrated that the NMDAR antagonists disrupted hippocampal function and that nicotine acted in the dorsal hippocampus to ameliorate the deficit in learning. The high-affinity nAChR antagonist Dihydro-β-erythroidine hydrobromide (DhβE) blocked the effects of nicotine on MK-801-induced deficits while the α7 nAChR antagonist methyllycaconitine citrate salt hydrate (MLA) did not. These results suggest that NMDARs and nAChRs may mediate similar hippocampal processes involved in contextual fear conditioning. Furthermore, these results may have implications for developing effective therapeutics for the cognitive deficits associated with schizophrenia because a large subset of patients with schizophrenia exhibit cognitive deficits that may be related to NMDAR dysfunction and smoke at much higher rates than the healthy population, which may be an attempt to ameliorate cognitive deficits.
Collapse
Affiliation(s)
- Jessica M André
- Department of Psychology, Temple University, Philadelphia, PA 19122, USA
| | | | | |
Collapse
|
33
|
Stevens KE, Cornejo B, Adams CE, Zheng L, Yonchek J, Hoffman KL, Christians U, Kem WR. Continuous administration of a selective alpha7 nicotinic partial agonist, DMXBA, improves sensory inhibition without causing tachyphylaxis or receptor upregulation in DBA/2 mice. Brain Res 2010; 1352:140-6. [PMID: 20599427 PMCID: PMC3932956 DOI: 10.1016/j.brainres.2010.06.063] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2010] [Revised: 06/22/2010] [Accepted: 06/24/2010] [Indexed: 10/19/2022]
Abstract
Stimulation of nicotinic receptors, specifically the alpha7 subtype, improves sensory inhibition and cognitive function in receptor deficient humans and rodents. However, stimulation with a full agonist, such as nicotine, produces rapid tachyphylaxis of the P20N40-measured sensory inhibition process. 3-(2,4-dimethoxybenzylidine) anabaseine (DMXBA, also GTS-21) selectively activates the alpha7 nicotinic receptor, and in acute administration studies, has been shown to improve deficient sensory inhibition in both humans and rodents with repeated dosing. Unlike nicotine, this partial agonist acted without inducing tachyphylaxis. Here, we assessed the ability of DMXBA to improve sensory inhibition in DBA/2 mice after 7 days of continuous administration via a subcutaneously implanted osmotic minipump. When assessed on day 8, mice receiving saline showed the characteristic deficient sensory inhibition seen with untreated DBA/2 mice. The 25- and 50-mg/ml infusion concentrations of DMXBA, but not the 100-mg/ml, produced significantly improved sensory inhibition in the mice, exclusively through a decrease in test amplitude. No concentration significantly upregulated hippocampal alpha7 receptor levels. DMXBA levels in the brain were higher than plasma at 2 of the 3 concentrations infused. These data suggest that continuous exposure to DMXBA does not significantly affect the underlying responsiveness of the sensory inhibition pathway to this partial agonist, nor cause receptor upregulation, at these relatively low brain concentrations. The ability of DMXBA to maintain its effectiveness during constant administration conditions may be due to an ability to activate alpha7 receptors at low concentrations, and consequently low fractional occupancy of the five possible binding sites on this homomeric receptor.
Collapse
Affiliation(s)
- Karen E Stevens
- Medical Research Service, Veterans Affairs Medical Center, Denver, CO, USA.
| | | | | | | | | | | | | | | |
Collapse
|
34
|
Kohnomi S, Suemaru K, Goda M, Choshi T, Hibino S, Kawasaki H, Araki H. Ameliorating effects of tropisetron on dopaminergic disruption of prepulse inhibition via the α7 nicotinic acetylcholine receptor in Wistar rats. Brain Res 2010; 1353:152-8. [DOI: 10.1016/j.brainres.2010.07.037] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2010] [Revised: 07/13/2010] [Accepted: 07/14/2010] [Indexed: 10/19/2022]
|
35
|
Shiina A, Shirayama Y, Niitsu T, Hashimoto T, Yoshida T, Hasegawa T, Haraguchi T, Kanahara N, Shiraishi T, Fujisaki M, Fukami G, Nakazato M, Iyo M, Hashimoto K. A randomised, double-blind, placebo-controlled trial of tropisetron in patients with schizophrenia. Ann Gen Psychiatry 2010; 9:27. [PMID: 20573264 PMCID: PMC2901366 DOI: 10.1186/1744-859x-9-27] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/01/2010] [Accepted: 06/24/2010] [Indexed: 11/23/2022] Open
Abstract
BACKGROUND Cognitive deficits in schizophrenia are associated with psychosocial deficits that are primarily responsible for the poor long-term outcome of this disease. Auditory sensory gating P50 deficits are correlated with neuropsychological deficits in attention, one of the principal cognitive disturbances in schizophrenia. Our studies suggest that the alpha7 nicotinic acetylcholine receptor (alpha7 nAChR) agonist tropisetron might be a potential therapeutic drug for cognitive deficits in schizophrenia. Therefore, it is of particular interest to investigate the effects of tropisetron on the cognitive deficits in patients with schizophrenia. METHODS A randomised, placebo-controlled trial of tropisetron in patients with schizophrenia was performed. A total of 40 patients with chronic schizophrenia who had taken risperidone (2 to 6 mg/day) were enrolled. Subjects were randomly assigned to a fixed titration of tropisetron (n = 20, 10 mg/day) or placebo (n = 20) in an 8-week double-blind trial. Auditory sensory gating P50 deficits and Quality of Life Scale (QLS), Cambridge Neuropsychological Test Automated Battery (CANTAB), and Positive and Negative Syndrome Scale (PANSS) scores were measured. RESULTS In all, 33 patients completed the trial. Tropisetron was well tolerated. Administration of tropisetron, but not placebo, significantly improved auditory sensory gating P50 deficits in non-smoking patients with schizophrenia. The score on the rapid visual information processing (sustained visual attention) task of CANTAB was significantly improved by tropisetron treatment. Total and subscale scores of PANSS were not changed by this trial. QLS scores in the all patients, but not non-smoking patients, were significantly improved by tropisetron trial. CONCLUSIONS This first randomised, double-blind, placebo-controlled trial supports the safety and efficacy of adjunctive tropisetron for treatment of cognitive deficits in schizophrenia.
Collapse
Affiliation(s)
- Akihiro Shiina
- Department of Psychiatry, Chiba University Hospital, Chiba, Japan
| | - Yukihiko Shirayama
- Department of Mental Health, Teikyo University Chiba Medical Center, Chiba, Japan
| | - Tomihisa Niitsu
- Department of Psychiatry, Chiba University Graduate School of Medicine, Chiba, Japan
| | - Tasuku Hashimoto
- Department of Psychiatry, Chiba University Graduate School of Medicine, Chiba, Japan
| | - Taisuke Yoshida
- Department of Psychiatry, Chiba University Graduate School of Medicine, Chiba, Japan
| | - Tadashi Hasegawa
- Department of Psychiatry, Chiba University Hospital, Chiba, Japan
| | - Tadashi Haraguchi
- Department of Psychiatry, Chiba University Graduate School of Medicine, Chiba, Japan
| | - Nobuhisa Kanahara
- Department of Psychiatry, Chiba University Graduate School of Medicine, Chiba, Japan
| | - Tetsuya Shiraishi
- Department of Psychiatry, Chiba University Graduate School of Medicine, Chiba, Japan
| | - Mihisa Fujisaki
- Department of Psychiatry, Chiba University Hospital, Chiba, Japan
| | - Goro Fukami
- Department of Psychiatry, Chiba University Hospital, Chiba, Japan
| | - Michiko Nakazato
- Department of Psychiatry, Chiba University Hospital, Chiba, Japan
| | - Masaomi Iyo
- Department of Psychiatry, Chiba University Hospital, Chiba, Japan
- Department of Psychiatry, Chiba University Graduate School of Medicine, Chiba, Japan
| | - Kenji Hashimoto
- Division of Clinical Neuroscience, Chiba University Center for Forensic Mental Health, Chiba, Japan
| |
Collapse
|
36
|
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.
Collapse
Affiliation(s)
- Jun Toyohara
- Division of Clinical Neuroscience, Chiba University Center for Forensic Mental Health, Chiba, Japan
| | | |
Collapse
|
37
|
Rudnick ND, Strasser AA, Phillips JM, Jepson C, Patterson F, Frey JM, Turetsky BI, Lerman C, Siegel SJ. Mouse model predicts effects of smoking and varenicline on event-related potentials in humans. Nicotine Tob Res 2010; 12:589-97. [PMID: 20395358 DOI: 10.1093/ntr/ntq049] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
BACKGROUND Nicotine alters auditory event-related potentials (ERPs) in rodents and humans and is an effective treatment for smoking cessation. Less is known about the effects of the partial nicotine agonist varenicline on ERPs. METHODS We measured the effects of varenicline and nicotine on the mouse P20 and varenicline and smoking on the human P50 in a paired-click task. Eighteen mice were tested following nicotine, varenicline, and their combination. One hundred and fourteen current smokers enrolled in a placebo-controlled within-subject crossover study to test the effects of varenicline during smoking and abstinence. Thirty-two subjects participated in the ERP study, with half receiving placebo first and half varenicline first (VP). RESULTS Nicotine and varenicline enhanced mouse P20 amplitude, while nicotine improved P20 habituation by selectively increasing the first-click response. Similar to mice, abstinence reduced P50 habituation relative to smoking by reducing the first-click response. There was no effect of varenicline on P50 amplitude during abstinence across subjects. However, there was a significant effect of medication order on P50 amplitude during abstinence. Subjects in the PV group displayed reduced P50 during abstinence, which was blocked by varenicline. However, subjects in the VP group did not display abstinence-induced P50 reduction. CONCLUSIONS Data suggest that smoking improves sensory processing. Varenicline mimics amplitude changes associated with nicotine and smoking but fails to alter habituation. The effect of medication order suggests a possible carryover effect from the previous arm. This study supports the predictive validity of ERPs in mice as a marker of drug effects in human studies.
Collapse
Affiliation(s)
- Noam D Rudnick
- Department of Psychiatry, University of Pennsylvania, Philadelphia, PA 19104, USA
| | | | | | | | | | | | | | | | | |
Collapse
|
38
|
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.
Collapse
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.
| | | | | | | |
Collapse
|
39
|
Tropisetron attenuates naloxone-induced place aversion in single-dose morphine-treated rats: role of alpha7 nicotinic receptors. Eur J Pharmacol 2009; 609:74-7. [PMID: 19374878 DOI: 10.1016/j.ejphar.2008.12.051] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2008] [Revised: 12/11/2008] [Accepted: 12/23/2008] [Indexed: 11/20/2022]
Abstract
We have previously reported that acute dependence can occur when naloxone is administered 24 h after even a single dose of morphine, and that nicotine attenuates this naloxone-precipitated withdrawal syndrome. In the present study, we studied the effect of tropisetron, an alpha7 nicotinic receptor agonist and 5-hydroxytryptamine 3 (5-HT(3)) receptor antagonist, on place aversion induced by naloxone in morphine-treated rats. Place aversion was significantly attenuated by pre-administered tropisetron (1.0 and 2.0 mg/kg, i. p.) in a dose-dependent manner, however tropisetron alone had no effect in a place-conditioning paradigm. This attenuation was completely antagonized by mecamylamine (1.0 mg/kg, s.c.), which is a central nicotinic receptor antagonist, but not by ondansetron (0.3 and 1.0 mg/kg, s.c.), a 5-HT(3) receptor antagonist. Furthermore, methyllycaconitine (1.0 and 2.0 mg/kg, s.c.), an alpha7 nicotinic acetylcholine receptor antagonist, but not dihydroxy-beta-erithroidine (1.0 and 2.0 mg/kg, s.c.), an alpha4beta2 nicotinic acetylcholine receptor antagonist, also antagonized the inhibitory effect of tropisetron. These findings suggest that tropisetron attenuates place aversion induced by naloxone in single-dose morphine-treated rats via alpha7 nicotinic receptors.
Collapse
|
40
|
Stevens KE, Adams CE, Mellott TJ, Robbins E, Kisley MA. Perinatal choline deficiency produces abnormal sensory inhibition in Sprague-Dawley rats. Brain Res 2008; 1237:84-90. [PMID: 18778692 DOI: 10.1016/j.brainres.2008.08.047] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2008] [Revised: 08/14/2008] [Accepted: 08/15/2008] [Indexed: 10/21/2022]
Abstract
Adequate choline levels in rodents during gestation have been shown to be critical to several functions, including certain learning and memory functions, when tested at adulthood. Choline is a selective agonist for the alpha7 nicotinic receptor which appears in development before acetylcholine is present. Normal sensory inhibition is dependent, in part, upon sufficient numbers of this receptor in the hippocampus. The present study assessed sensory inhibition in Sprague-Dawley rats gestated on normal (1.1 g/kg), deficient (0 g/kg) or supplemented (5 g/kg) choline in the maternal diet during the critical period for cholinergic cell development (E12-18). Rats gestated on deficient choline showed abnormal sensory inhibition when tested at adulthood, while rats gestated on normal or supplemented choline showed normal sensory inhibition. Assessment of hippocampal alpha-bungarotoxin to visualize nicotinic alpha7 receptors revealed no difference between the gestational choline levels. These data suggest that attention to maternal choline levels for human pregnancy may be important to the normal functioning of the offspring.
Collapse
Affiliation(s)
- Karen E Stevens
- Medical Research Service, Department of Veterans Affairs Medical Center, Denver, CO, USA.
| | | | | | | | | |
Collapse
|
41
|
Simosky JK, Freedman R, Stevens KE. Olanzapine improves deficient sensory inhibition in DBA/2 mice. Brain Res 2008; 1233:129-36. [PMID: 18687314 DOI: 10.1016/j.brainres.2008.07.057] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2008] [Revised: 07/10/2008] [Accepted: 07/11/2008] [Indexed: 10/21/2022]
Abstract
Most schizophrenia patients do not inhibit their P50 auditory evoked potential to the second of duplicate auditory stimuli, reflecting a failure to inhibit responses to irrelevant sensory input. Typical antipsychotic drugs do not improve this deficit while some atypical antipsychotics do. A previous study using an animal model, deficient P20-N40 (which corresponds to the human P50) inhibitory processing in DBA/2 mice found that sensory inhibition was improved by clozapine, the prototypical atypical antipsychotic, but not by haloperidol, a typical antipsychotic. The improvement after clozapine was mediated by alpha7 nicotinic receptors. The present study addresses whether another atypical antipsychotic, olanzapine, will also improve sensory inhibition deficits in the mouse model. In vivo electrophysiological recordings of the P20-N40 auditory evoked potential in anesthetized DBA/2 mice, which spontaneously exhibit a schizophrenia-like inhibitory processing deficit, were obtained after olanzapine alone (0.01, 0.033, 0.1, 0.33 mg/kg, IP) and the efficacious dose of olanzapine (0.033 mg/kg, IP) in combination with either the alpha7 nicotinic receptor antagonist alpha-bungarotoxin or the alpha4beta2 nicotinic receptor antagonist di-hydro-beta-erythroidine. All doses of olanzapine produced improved P20-N40 inhibitory processing in DBA/2 mice. The normalization observed after the 0.033 mg/kg dose of olanzapine was due to a selective decrease in response to the second auditory stimulus indicating an increase in inhibitory processing. This improvement was blocked by pre-administration of alpha-bungarotoxin but not di-hydro-beta-erythroidine. Like clozapine, olanzapine acts via alpha7 nicotinic receptors to elicit improved inhibitory processing of auditory stimuli.
Collapse
Affiliation(s)
- Johanna K Simosky
- Department of Pharmacology, University of Colorado Health Sciences Center, Denver, Colorado, USA
| | | | | |
Collapse
|
42
|
Wildeboer KM, Stevens KE. Stimulation of the alpha4beta2 nicotinic receptor by 5-I A-85380 improves auditory gating in DBA/2 mice. Brain Res 2008; 1224:29-36. [PMID: 18582447 DOI: 10.1016/j.brainres.2008.06.007] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2008] [Revised: 06/03/2008] [Accepted: 06/04/2008] [Indexed: 11/17/2022]
Abstract
Abnormal auditory gating is a symptom of schizophrenia which has been proposed to be mediated through the alpha7 nicotinic acetylcholine receptor (nAChR). It has been shown that the non-selective nicotinic agonist nicotine has an influence on auditory gating in part by acting on the alpha4beta2 nAChR. The goal of this study was to determine the effect of 5-I A-85380, an agonist for the alpha4beta2 nAChR, in an inbred mouse model with a deficiency for auditory gating. Anesthetized DBA/2 mice were administered 5-I A-85380 alone and in combination with the alpha4beta2 nAChR antagonist, dihydro-beta-erythroidine, or the alpha7 nAChR antagonist, alpha-bungarotoxin. A recording electrode in the CA3 region of the hippocampus recorded P20-N40 waveforms in response to two auditory stimuli. The amplitudes of the response to the first and second clicks were used to determine TC ratios, the measure of auditory gating. 5-I A-85380 significantly decreased the TC ratios by selectively increasing the response amplitudes to the first click with no significant influence on the response amplitudes to the second click. The effect was blocked by dihydro-beta-erythroidine whereas alpha-bungarotoxin had no effect on response amplitude to either click. Although the alpha7 nAChR may mediate the hippocampal response of DBA/2 mice to the second click, the alpha4beta2 nAChR appears to modulate the response to the first click. Thus, the present study implicates the involvement of more than one subtype of nAChR in the auditory gating of DBA/2 mice, specifically the alpha4beta2 nAChR, and its role in the response amplitude to the first stimulus.
Collapse
Affiliation(s)
- Kristin M Wildeboer
- Department of Psychiatry, University of Colorado Denver, Aurora, CO 80045, USA.
| | | |
Collapse
|
43
|
Mann C, Croft RJ, Scholes KE, Dunne A, O'Neill BV, Leung S, Copolov D, Phan KL, Nathan PJ. Differential effects of acute serotonin and dopamine depletion on prepulse inhibition and p50 suppression measures of sensorimotor and sensory gating in humans. Neuropsychopharmacology 2008; 33:1653-66. [PMID: 17895917 DOI: 10.1038/sj.npp.1301556] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Schizophrenia is associated with impairments of sensorimotor and sensory gating as measured by prepulse inhibition (PPI) of the acoustic startle response and P50 suppression of the auditory event-related potential respectively. While serotonin and dopamine play an important role in the pathophysiology and treatment of schizophrenia, their role in modulating PPI and P50 suppression in humans is yet to be fully clarified. To further explore the role of serotonin and dopamine in PPI and P50 suppression, we examined the effects of acute tryptophan depletion (to decrease serotonin) and acute tyrosine/phenylalanine depletion (to decrease dopamine) on PPI and P50 suppression in healthy human participants. In addition, we also examined for the first time, the effects of simultaneous serotonin and dopamine depletion (ie combined monoamine depletion) on PPI and P50 suppression. The study was a double-blind, placebo-controlled cross-over design in which 16 healthy male participants completed the PPI and P50 paradigms under four acute treatment conditions: (a) balanced/placebo control, (b) acute tryptophan depletion, (c) acute tyrosine/phenylalanine depletion, and (d) acute tyrosine/phenylalanine/tryptophan depletion (combined monoamine depletion). Selective depletion of dopamine had no significant effect on either PPI or P50 suppression, whereas selective serotonin depletion significantly disrupted PPI, but not P50 suppression. Finally, the simultaneous depletion of both serotonin and dopamine resulted in significant reduction of both PPI and P50 suppression. We suggest these results can be explained by theories relating to optimal levels of monoaminergic neurotransmission and synergistic interactions between serotonergic and dopaminergic systems for normal 'gating' function. These findings suggest that a dysfunction in both serotonin and dopamine neurotransmission may, in part, be responsible for the gating deficits observed in schizophrenia, and their normalization following administration of atypical antipsychotic drugs.
Collapse
Affiliation(s)
- Collette Mann
- Behavioural Neuroscience Laboratory, School of Psychology, Psychiatry and Psychological Medicine, Monash University, Melbourne, VIC, Australia
| | | | | | | | | | | | | | | | | |
Collapse
|
44
|
Stevens KE, Adams CE, Yonchek J, Hickel C, Danielson J, Kisley MA. Permanent improvement in deficient sensory inhibition in DBA/2 mice with increased perinatal choline. Psychopharmacology (Berl) 2008; 198:413-20. [PMID: 18446322 DOI: 10.1007/s00213-008-1170-3] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/16/2007] [Accepted: 04/01/2008] [Indexed: 10/22/2022]
Abstract
RATIONALE Schizophrenia patients and certain inbred mouse strains (i.e., DBA/2) show deficient sensory inhibition which has been linked to reduced numbers of hippocampal alpha7 nicotinic receptors and to underlying polymorphisms in the promoter region for the alpha7 gene. Increasing maternal dietary choline, a selective alpha7 agonist, during gestation has been shown to produce long-term changes in adult offspring behavior (i.e., improved learning and memory in rats). OBJECTIVES The objective of this study is to improve sensory inhibition in DBA/2 mice through maternal choline supplementation. MATERIALS AND METHODS DBA/2 dams were placed on normal (1.1 g/kg) or supplemented (5 g/kg) choline diet throughout gestation and lactation. Offspring were placed on normal diet at weaning and were assessed for sensory inhibition parameters at adulthood. Evoked EEG responses to identical paired auditory stimuli were compared. At the end of the study, the brains were collected for autoradiographic assessment of hippocampal levels of alpha-bungarotoxin binding to visualize alpha7 nicotinic receptors. RESULTS Offspring mice which were choline supplemented during gestation showed significantly improved sensory inhibition compared to mice gestated on the normal choline diet. The improvement was produced by a significant reduction in the response to the second stimulus, demonstrating improved inhibition to that stimulus. There was a concurrent increase in alpha7 receptor numbers in both the CA1 and dentate gyrus regions of the hippocampus suggesting that this increase may be responsible for the improved inhibition. CONCLUSIONS These data show that gestational choline supplementation produces permanent improvement in a deficit associated with schizophrenia and may have implications for human prenatal nutrition.
Collapse
Affiliation(s)
- Karen E Stevens
- Medical Research, Veterans Affairs Medical Center, 1055 Clermont Avenue, Denver, CO 80220, USA.
| | | | | | | | | | | |
Collapse
|
45
|
Abrams DJ, Zheng L, Choo K, Yang JJ, Wei W, Anchordoquy TJ, Zawia NH, Stevens KE. An initial animal proof-of-concept study for central administration of clozapine to schizophrenia patients. Schizophr Res 2008; 100:86-96. [PMID: 18178385 PMCID: PMC2288754 DOI: 10.1016/j.schres.2007.10.012] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/16/2007] [Revised: 10/19/2007] [Accepted: 10/24/2007] [Indexed: 10/22/2022]
Abstract
While clozapine is the acknowledged superior pharmacotherapeutic for the treatment of schizophrenia, the side effect profile, which includes potentially fatal complications, limits its usefulness. Central administration of clozapine directly into the brain could circumvent many of the side effect issues due to the dramatic reduction in dose and the limitation of the drug primarily to the CNS. The present study demonstrates that clozapine can be formulated as a stable solution at physiological pH, which does not have in vitro neurotoxic effects at concentrations which may be effective at treating symptoms. Acute central administration improved auditory gating deficits in a mouse model of schizophrenia-like deficits. Assessment of behavioral alterations in rats receiving chronic central infusions of clozapine via osmotic minipump was performed with the open field and elevated plus mazes. Neither paradigm revealed any detrimental effects of the infusion. While these data represent only an initial investigation, they none-the-less suggest that central administration of clozapine may be a viable alternate therapeutic approach for schizophrenia patients which may be effective in symptom reduction without causing behavioral or neurotoxic effects.
Collapse
Affiliation(s)
- Daniel J. Abrams
- Department of Psychiatry, University of Colorado at Denver and Health Sciences Center, Aurora, CO 80045
| | - Lijun Zheng
- Department of Psychiatry, University of Colorado at Denver and Health Sciences Center, Aurora, CO 80045
| | - Kevin Choo
- Department of Psychiatry, University of Colorado at Denver and Health Sciences Center, Aurora, CO 80045
| | - Jun J Yang
- School of Pharmacy, University of Colorado at Denver and Health Sciences Center, Aurora, CO 80045
| | - Wei Wei
- Department of Biomedical and Pharmaceutical Sciences, University of Rhode Island, Kingston, RI
| | - Thomas J. Anchordoquy
- School of Pharmacy, University of Colorado at Denver and Health Sciences Center, Aurora, CO 80045
| | - Nasser H. Zawia
- Department of Biomedical and Pharmaceutical Sciences, University of Rhode Island, Kingston, RI
| | - Karen E. Stevens
- Department of Psychiatry, University of Colorado at Denver and Health Sciences Center, Aurora, CO 80045,Medical Research, Veterans Affairs Medical Center, Denver CO
| |
Collapse
|
46
|
Lightfoot AP, Kew JNC, Skidmore J. Alpha7 nicotinic acetylcholine receptor agonists and positive allosteric modulators. PROGRESS IN MEDICINAL CHEMISTRY 2008; 46:131-71. [PMID: 18381125 DOI: 10.1016/s0079-6468(07)00003-3] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Affiliation(s)
- Andrew P Lightfoot
- Medicinal Chemistry, Psychiatry CEDD, GlaxoSmithKline, New Frontiers Science Park, Third Avenue, Harlow, Essex, CM19 5AW, UK
| | | | | |
Collapse
|
47
|
Hashimoto K, Ishima T, Fujita Y, Matsuo M, Kobashi T, Takahagi M, Tsukada H, Iyo M. Phencyclidine-induced cognitive deficits in mice are improved by subsequent subchronic administration of the novel selective alpha7 nicotinic receptor agonist SSR180711. Biol Psychiatry 2008; 63:92-7. [PMID: 17601496 DOI: 10.1016/j.biopsych.2007.04.034] [Citation(s) in RCA: 92] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/05/2006] [Revised: 04/12/2007] [Accepted: 04/24/2007] [Indexed: 10/23/2022]
Abstract
BACKGROUND Accumulating evidence suggests that alpha7 nicotinic receptor (alpha7 nAChR) agonists could be potential therapeutic drugs for cognitive deficits in schizophrenia. The present study was undertaken to examine the effects of the novel selective alpha7 nAChR agonist SSR180711 on cognitive deficits in mice after repeated administration of the N-methyl-D-aspartate receptor antagonist phencyclidine (PCP). METHODS Saline or PCP (10 mg/kg/day for 10 days) was administered to mice. Subsequently, vehicle, SSR180711 (.3 or 3.0 mg/kg/day), SSR180711 (3.0 mg/kg/day) + the selective alpha7 nAChR antagonist methyllycaconitine (MLA; 3.0 mg/kg/day), or MLA (3.0 mg/kg/day) was administered IP for 2 consecutive weeks. Twenty-four hours after the final administration, a novel object recognition test was performed. RESULTS The PCP-induced cognitive deficits were significantly improved by subsequent subchronic (2-week) administration of SSR180711 (3.0 mg/kg). The effects of SSR180711 (3.0 mg/kg) were significantly antagonized by co-administration of MLA (3.0 mg/kg). Furthermore, Western blot analysis and immunohistochemistry revealed that levels of alpha7 nAChRs in the frontal cortex and hippocampus of the PCP (10 mg/kg/day for 10 days)-treated mice were significantly lower than those of saline-treated mice. CONCLUSIONS These findings suggest that repeated PCP administration significantly decreased the density of alpha7 nAChRs in the brain and that the alpha7 nAChR agonist SSR180711 could ameliorate cognitive deficits in mice after repeated administration of PCP. Therefore, alpha7 nAChR agonists including SSR180711 are potential therapeutic drugs for treating cognitive deficits in schizophrenic patients.
Collapse
Affiliation(s)
- Kenji Hashimoto
- Division of Clinical Neuroscience, Chiba University Center for Forensic Mental Health, Chiba, Japan.
| | | | | | | | | | | | | | | |
Collapse
|
48
|
Adams CE, Yonchek JC, Zheng L, Collins AC, Stevens KE. Altered hippocampal circuit function in C3H alpha7 null mutant heterozygous mice. Brain Res 2007; 1194:138-45. [PMID: 18199426 DOI: 10.1016/j.brainres.2007.12.007] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2007] [Revised: 11/30/2007] [Accepted: 12/03/2007] [Indexed: 11/24/2022]
Abstract
The alpha7 subtype of nicotinic receptor is highly expressed in the hippocampus where it is purported to modulate release of the inhibitory neurotransmitter gamma-aminobutyric acid (GABA). The alpha7 receptor-mediated release of GABA is thought to contribute to hippocampal inhibition (gating) of response to repetitive auditory stimulation. This hypothesis is supported by observations of hippocampal auditory gating deficits in mouse strains with low levels of hippocampal alpha7 receptors compared to strains with high levels of hippocampal alpha7 receptors. The difficulty with comparisons between mouse strains, however, is that different strains have different genetic backgrounds. Thus, the observed interstrain differences in hippocampal auditory gating might result from factors other than interstrain variations in the density of hippocampal alpha7 receptors. To address this issue, hippocampal binding of the alpha7 receptor-selective antagonist alpha-bungarotoxin as well as hippocampal auditory gating characteristics were compared in C3H wild type and C3H alpha7 receptor null mutant heterozygous mice. The C3H alpha7 heterozygous mice exhibited significant reductions in hippocampal alpha7 receptor levels and abnormal hippocampal auditory gating compared to the C3H wild type mice. In addition, a general increase in CA3 pyramidal neuron responsivity was observed in the heterozygous mice compared to the wild type mice. These data suggest that decreasing hippocampal alpha7 receptor density results in a profound alteration in hippocampal circuit function.
Collapse
Affiliation(s)
- C E Adams
- Medical Research, Veterans Affairs Medical Center, Denver, CO 80220, USA.
| | | | | | | | | |
Collapse
|
49
|
|
50
|
Young JW, Crawford N, Kelly JS, Kerr LE, Marston HM, Spratt C, Finlayson K, Sharkey J. Impaired attention is central to the cognitive deficits observed in alpha 7 deficient mice. Eur Neuropsychopharmacol 2007; 17:145-55. [PMID: 16650968 DOI: 10.1016/j.euroneuro.2006.03.008] [Citation(s) in RCA: 169] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/23/2005] [Revised: 03/02/2006] [Accepted: 03/21/2006] [Indexed: 11/27/2022]
Abstract
alpha7-Nicotinic acetylcholine receptors (alpha7-nAChR) have been implicated in a range of cognitive deficits in schizophrenia. Therefore we examined alpha7-nAChR knockout (KO), heterozygote (HT) and wildtype (WT) littermate mice in the 5-CSR (a rodent model of sustained attention) and odour span (a novel mouse working memory paradigm) tasks, and related performance to nAChR density. Whilst there was no difference between groups in baseline 5-CSR task performance, alpha7-nAChR KO's exhibited significantly higher omission levels compared to WT mice on increasing the attentional load, with HT mice performing at an intermediate level. Furthermore, alpha7-nAChR KO mice were significantly impaired in the odour span task when compared to WT mice, in a pattern consistent with impaired attention. These behavioural deficits were associated with the loss of alpha7-nAChRs, as alpha4beta2-nAChR density was unaltered in these mice. Thus these studies intimate that the attentional impairment in alpha7-nAChR transgenic mice maybe core to other deficits in cognition.
Collapse
Affiliation(s)
- Jared W Young
- Astellas CNS Research in Edinburgh, The University of Edinburgh, The Chancellor's Building, 49 Little France Crescent, EH16 4SB, UK
| | | | | | | | | | | | | | | |
Collapse
|