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Vijayraghavan S, Everling S. Neuromodulation of Persistent Activity and Working Memory Circuitry in Primate Prefrontal Cortex by Muscarinic Receptors. Front Neural Circuits 2021; 15:648624. [PMID: 33790746 PMCID: PMC8005543 DOI: 10.3389/fncir.2021.648624] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2021] [Accepted: 02/11/2021] [Indexed: 12/31/2022] Open
Abstract
Neuromodulation by acetylcholine plays a vital role in shaping the physiology and functions of cerebral cortex. Cholinergic neuromodulation influences brain-state transitions, controls the gating of cortical sensory stimulus responses, and has been shown to influence the generation and maintenance of persistent activity in prefrontal cortex. Here we review our current understanding of the role of muscarinic cholinergic receptors in primate prefrontal cortex during its engagement in the performance of working memory tasks. We summarize the localization of muscarinic receptors in prefrontal cortex, review the effects of muscarinic neuromodulation on arousal, working memory and cognitive control tasks, and describe the effects of muscarinic M1 receptor stimulation and blockade on the generation and maintenance of persistent activity of prefrontal neurons encoding working memory representations. Recent studies describing the pharmacological effects of M1 receptors on prefrontal persistent activity demonstrate the heterogeneity of muscarinic actions and delineate unexpected modulatory effects discovered in primate prefrontal cortex when compared with studies in rodents. Understanding the underlying mechanisms by which muscarinic receptors regulate prefrontal cognitive control circuitry will inform the search of muscarinic-based therapeutic targets in the treatment of neuropsychiatric disorders.
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Affiliation(s)
- Susheel Vijayraghavan
- Department of Physiology and Pharmacology, The University of Western Ontario, London, ON, Canada
| | - Stefan Everling
- Department of Physiology and Pharmacology, The University of Western Ontario, London, ON, Canada.,Robarts Research Institute, The University of Western Ontario, London, ON, Canada
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2
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Hamann M, Plank J, Richter F, Bode C, Smiljanic S, Creed M, Nobrega JN, Richter A. Alterations of M1 and M4 acetylcholine receptors in the genetically dystonic (dt sz) hamster and moderate antidystonic efficacy of M1 and M4 anticholinergics. Neuroscience 2017; 357:84-98. [PMID: 28596119 DOI: 10.1016/j.neuroscience.2017.05.051] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2017] [Revised: 04/28/2017] [Accepted: 05/29/2017] [Indexed: 11/30/2022]
Abstract
Striatal cholinergic dysfunction has been suggested to play a critical role in the pathophysiology of dystonia. In the dtsz hamster, a phenotypic model of paroxysmal dystonia, M1 antagonists exerted moderate antidystonic efficacy after acute systemic administration. In the present study, we examined the effects of the M4 preferring antagonist tropicamid and whether long-term systemic or acute intrastriatal injections of the M1 preferring antagonist trihexyphenidyl are more effective in mutant hamsters. Furthermore, M1 and M4 receptors were analyzed by autoradiography and immunohistochemistry. Tropicamide retarded the onset of dystonic attacks, as previously observed after acute systemic administration of trihexyphenidyl. Combined systemic administration of trihexyphenidyl (30mg/kg) and tropicamide (15mg/kg) reduced the severity in acute trials and delayed the onset of dystonia during long-term treatment. In contrast, acute striatal microinjections of trihexyphenidyl, tropicamid or the positive allosteric M4 receptor modulator VU0152100 did not exert significant effects. Receptor analyses revealed changes of M1 receptors in the dorsomedial striatum, suggesting that the cholinergic system is involved in abnormal striatal plasticity in dtsz hamsters, but the pharmacological data argue against a crucial role on the phenotype in this animal model. However, antidystonic effects of tropicamide after systemic administration point to a novel therapeutic potential of M4 preferring anticholinergics for the treatment of dystonia.
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Affiliation(s)
- Melanie Hamann
- Institute of Pharmacology and Toxicology, Faculty of Veterinary Medicine, Justus Liebig University Giessen, Schubertstrasse 81, BFS, 35392 Giessen, Germany.
| | - Jagoda Plank
- Institute of Pharmacology and Toxicology, Department of Veterinary Medicine, Freie Universität Berlin, Koserstrasse 20, 14195 Berlin, Germany
| | - Franziska Richter
- Institute of Pharmacology, Pharmacy and Toxicology, Faculty of Veterinary Medicine, University of Leipzig, An den Tierkliniken 15, Leipzig, Germany
| | - Christoph Bode
- Institute of Pharmacology, Pharmacy and Toxicology, Faculty of Veterinary Medicine, University of Leipzig, An den Tierkliniken 15, Leipzig, Germany
| | - Sinisa Smiljanic
- Institute of Pharmacology and Toxicology, Department of Veterinary Medicine, Freie Universität Berlin, Koserstrasse 20, 14195 Berlin, Germany
| | - Meaghan Creed
- Neuroimaging Research Section, Centre for Addiction and Mental Health, Toronto, Canada
| | - José N Nobrega
- Institute of Pharmacology and Toxicology, Department of Veterinary Medicine, Freie Universität Berlin, Koserstrasse 20, 14195 Berlin, Germany
| | - Angelika Richter
- Institute of Pharmacology, Pharmacy and Toxicology, Faculty of Veterinary Medicine, University of Leipzig, An den Tierkliniken 15, Leipzig, Germany.
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3
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Lauer AM, Behrens D, Klump G. Acoustic startle modification as a tool for evaluating auditory function of the mouse: Progress, pitfalls, and potential. Neurosci Biobehav Rev 2017; 77:194-208. [PMID: 28327385 PMCID: PMC5446932 DOI: 10.1016/j.neubiorev.2017.03.009] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2017] [Revised: 02/23/2017] [Accepted: 03/13/2017] [Indexed: 12/16/2022]
Abstract
Acoustic startle response (ASR) modification procedures, especially prepulse inhibition (PPI), are increasingly used as behavioral measures of auditory processing and sensorimotor gating in rodents due to their perceived ease of implementation and short testing times. In practice, ASR and PPI procedures are extremely variable across animals, experimental setups, and studies, and the interpretation of results is subject to numerous caveats and confounding influences. We review considerations for modification of the ASR using acoustic stimuli, and we compare the sensitivity of PPI procedures to more traditional operant psychoacoustic techniques. We also discuss non-auditory variables that must be considered. We conclude that ASR and PPI measures cannot substitute for traditional operant techniques due to their low sensitivity. Additionally, a substantial amount of pilot testing must be performed to properly optimize an ASR modification experiment, negating any time benefit over operant conditioning. Nevertheless, there are some circumstances where ASR measures may be the only option for assessing auditory behavior, such as when testing mouse strains with early-onset hearing loss or learning impairments.
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Affiliation(s)
- Amanda M Lauer
- Department of Otolaryngology-Head and Neck Surgery and Center for Hearing and Balance, Johns Hopkins University, 515 Traylor Building, 720 Rutland Ave., Baltimore, MD 21205, USA.
| | - Derik Behrens
- Cluster of Excellence Hearing4all, Animal Physiology & Behavior Group, Department for Neuroscience, School of Medicine and Health Sciences, Carl Von Ossietzky University Oldenburg, Carl Von Ossietzky Str. 9-11, 26111 Oldenburg, Germany
| | - Georg Klump
- Cluster of Excellence Hearing4all, Animal Physiology & Behavior Group, Department for Neuroscience, School of Medicine and Health Sciences, Carl Von Ossietzky University Oldenburg, Carl Von Ossietzky Str. 9-11, 26111 Oldenburg, Germany
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4
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Pupil response to tropicamide following corneal crosslinking. Eur J Ophthalmol 2016; 26:394-7. [PMID: 26833233 DOI: 10.5301/ejo.5000758] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/11/2016] [Indexed: 11/20/2022]
Abstract
PURPOSE To evaluate the effect of corneal crosslinking (CXL) with ultraviolet A (UVA) irradiation on pupil response to tropicamide 0.5% instillation. METHODS This prospective interventional study enrolled 17 patients (19 eyes) with progressive keratoconus who underwent CXL with UVA irradiation. Central corneal thickness (CCT) was evaluated with the use of anterior segment optical coherence tomography (Visante OCT 3.0). Pupil diameter was measured with the use of Colvard infrared pupillometer before the instillation of tropicamide 0.5% and after the instillation of tropicamide every 5 minutes for total duration of 30 minutes. Corneal epithelial integrity was examined with the use of fluorescein dye staining. Measurements were performed 1 day preoperatively and 1 month postoperatively, with emphasis on simulating the same light conditions regarding the pupil measurements. RESULTS No intraoperative or postoperative complications were observed in any of the patients. Mean CCT decreased significantly (p<0.001) 1 month postoperatively. Mean postoperative pupil size did not change significantly at any time point compared to the mean preoperative measurements. CONCLUSIONS The CXL procedure seems not to impair effectiveness of topical drugs, using pupil size measurements after tropicamide 0.5% instillation.
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Shormanov VK, Pravdyuk MF, Cheked MV, Barannikova VV. [The distribution of tropicamide in the body of warm-blooded animals after its intragastric administration]. Sud Med Ekspert 2016; 59:27-34. [PMID: 27070036 DOI: 10.17116/sudmed201659227-34] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The objective of the present study was to elucidate the peculiar features of the distribution of N-ethyl-3-hydroxy-2-phenyl-N-(piridin-4-yl-methyl)propanamide (tropicamide) in the body of warm-blooded animals (rats) after its intragastric administration. The following methods were employed in the study: TLC, chromogenic reactions, electronic spectrophotometry, and GC-MS. The results of the quantitative analysis of N-ethyl-3-hydroxy-2-phenyl-N-(piridin-4-yl-methyl)propanamide in different organs of warm-blooded animals (rats) were compared within 20 minutes, 2.5 and 6 hours after its single intragastric administration at a dose equivalent to 1.5 LD50 of the toxic substance. It was shown that at all time intervals the maximum amount of tropicamide was present in the tissues of the stomach. Small intestines, their contents, brain, lungs, and spleen.
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Affiliation(s)
- V K Shormanov
- Kursk State Medical University, Kursk, Russia, 305041
| | - M F Pravdyuk
- Republican Narcological Dispensary, Ministry of Health, Republic of North Ossetia, Vladikavkaz, Russia, 362027
| | - M V Cheked
- Kursk State Medical University, Kursk, Russia, 305041
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Smith C, Lee R, Moran A, Sipos M. Repeated low-dose exposures to sarin, soman, or VX affect acoustic startle in guinea pigs. Neurotoxicol Teratol 2016; 54:36-45. [DOI: 10.1016/j.ntt.2016.01.005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2015] [Revised: 12/21/2015] [Accepted: 01/28/2016] [Indexed: 10/22/2022]
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Carruthers SP, Gurvich CT, Rossell SL. The muscarinic system, cognition and schizophrenia. Neurosci Biobehav Rev 2015; 55:393-402. [PMID: 26003527 DOI: 10.1016/j.neubiorev.2015.05.011] [Citation(s) in RCA: 68] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2014] [Revised: 04/21/2015] [Accepted: 05/12/2015] [Indexed: 12/26/2022]
Abstract
An increasing body of evidence has implicated the central muscarinic system as contributing to a number of symptoms of schizophrenia and serving as a potential target for pharmaceutical interventions. A theoretical review is presented that focuses on the central muscarinic system's contribution to the cognitive symptoms of schizophrenia. The aim is to bridge the void between pertinent neuropsychological and neurobiological research to provide an explanatory account of the role that the central muscarinic system plays in the symptoms of schizophrenia. First, there will be a brief overview of the relevant neuropsychological schizophrenia literature, followed by a concise introduction to the central muscarinic system. Subsequently, we will draw from animal, neuropsychological and pharmacological literature, and discuss the findings in relation to cognition, schizophrenia and the muscarinic system. Whilst unifying the multiple domains of research into a concise review will act as a useful line of enquiry into the central muscarinic systems contribution to the symptoms of schizophrenia, it will be made apparent that more research is needed in this field.
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Affiliation(s)
- Sean P Carruthers
- Brain and Psychological Sciences Research Centre (BPsyC), Faculty of Health, Arts, Design, Swinburne University of Technology, Melbourne 3122, VIC, Australia; Monash Alfred Psychiatry Research Centre (MAPrc), Monash University Central Clinical School and The Alfred Hospital, Melbourne 3004, VIC, Australia.
| | - Caroline T Gurvich
- Monash Alfred Psychiatry Research Centre (MAPrc), Monash University Central Clinical School and The Alfred Hospital, Melbourne 3004, VIC, Australia
| | - Susan L Rossell
- Brain and Psychological Sciences Research Centre (BPsyC), Faculty of Health, Arts, Design, Swinburne University of Technology, Melbourne 3122, VIC, Australia; Monash Alfred Psychiatry Research Centre (MAPrc), Monash University Central Clinical School and The Alfred Hospital, Melbourne 3004, VIC, Australia; Psychiatry, St Vincent's Hospital, Melbourne 3065, VIC, Australia
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8
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Curtin PCP, Preuss T. Glycine and GABAA receptors mediate tonic and phasic inhibitory processes that contribute to prepulse inhibition in the goldfish startle network. Front Neural Circuits 2015; 9:12. [PMID: 25852486 PMCID: PMC4371714 DOI: 10.3389/fncir.2015.00012] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2014] [Accepted: 03/04/2015] [Indexed: 11/13/2022] Open
Abstract
Prepulse inhibition (PPI) is understood as a sensorimotor gating process that attenuates sensory flow to the startle pathway during early stages (20–1000 ms) of information processing. Here, we applied in vivo electrophysiology and pharmacology to determine if PPI is mediated by glycine receptors (GlyRs) and/or GABAA receptors (GABAARs) in the goldfish auditory startle circuit. Specifically, we used selective antagonists to dissect the contributions of target receptors on sound-evoked postsynaptic potentials (PSPs) recorded in the neurons that initiate startle, the Mauthner-cells (M-cell). We found that strychnine, a GlyR antagonist, disrupted a fast-activated (5 ms) and rapidly (<50 ms) decaying (feed-forward) inhibitory process that contributes to PPI at 20 ms prepulse/pulse inter-stimulus intervals (ISI). Additionally we observed increases of the evoked postsynaptic potential (PSP) peak amplitude (+87.43 ± 21.53%, N = 9) and duration (+204 ± 48.91%, N = 9). In contrast, treatment with bicuculline, a GABAAR antagonist, caused a general reduction in PPI across all tested interstimulus intervals (ISIs) (20–500 ms). Bicuculline also increased PSP peak amplitude (+133.8 ± 10.3%, N = 5) and PSP duration (+284.95 ± 65.64%, N = 5). Treatment with either antagonist also tonically increased post-synaptic excitability in the M-cells, reflected by an increase in the magnitude of antidromically-evoked action potentials (APs) by 15.07 ± 3.21%, N = 7 and 16.23 ± 7.08%, N = 5 for strychnine and bicuculline, respectively. These results suggest that GABAARs and GlyRs are functionally segregated to short- and longer-lasting sound-evoked (phasic) inhibitory processes that contribute to PPI, with the mediation of tonic inhibition by both receptor systems being critical for gain control within the M-cell startle circuit.
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Affiliation(s)
- Paul C P Curtin
- Graduate Center, City University of New York New York, NY, USA
| | - Thomas Preuss
- Hunter College, City University of New York New York, NY, USA
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Wischhof L, Irrsack E, Osorio C, Koch M. Prenatal LPS-exposure--a neurodevelopmental rat model of schizophrenia--differentially affects cognitive functions, myelination and parvalbumin expression in male and female offspring. Prog Neuropsychopharmacol Biol Psychiatry 2015; 57:17-30. [PMID: 25455585 DOI: 10.1016/j.pnpbp.2014.10.004] [Citation(s) in RCA: 119] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/08/2014] [Revised: 10/08/2014] [Accepted: 10/10/2014] [Indexed: 01/15/2023]
Abstract
Maternal infection during pregnancy increases the risk for the offspring to develop schizophrenia. Gender differences can be seen in various features of the illness and sex steroid hormones (e.g. estrogen) have strongly been implicated in the disease pathology. In the present study, we evaluated sex differences in the effects of prenatal exposure to a bacterial endotoxin (lipopolysaccharide, LPS) in rats. Pregnant dams received LPS-injections (100 μg/kg) at gestational day 15 and 16. The offspring was then tested for prepulse inhibition (PPI), locomotor activity, anxiety-like behavior and object recognition memory at various developmental time points. At postnatal day (PD) 33 and 60, prenatally LPS-exposed rats showed locomotor hyperactivity which was similar in male and female offspring. Moreover, prenatal LPS-treatment caused PPI deficits in pubertal (PD45) and adult (PD90) males while PPI impairments were found only at PD45 in prenatally LPS-treated females. Following prenatal LPS-administration, recognition memory for objects was impaired in both sexes with males being more severely affected. Additionally, we assessed prenatal infection-induced alterations of parvalbumin (Parv) expression and myelin fiber density. Male offspring born to LPS-challenged mothers showed decreased myelination in cortical and limbic brain regions as well as reduced numbers of Parv-expressing cells in the medial prefrontal cortex (mPFC), hippocampus and entorhinal cortex. In contrast, LPS-exposed female rats showed only a modest decrease in myelination and Parv immunoreactivity. Collectively, our data indicate that some of the prenatal immune activation effects are sex dependent and further strengthen the importance of taking into account gender differences in animal models of schizophrenia.
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Affiliation(s)
- Lena Wischhof
- Brain Research Institute, Department of Neuropharmacology, University of Bremen, Hochschulring 18, 28359 Bremen, Germany.
| | - Ellen Irrsack
- Brain Research Institute, Department of Neuropharmacology, University of Bremen, Hochschulring 18, 28359 Bremen, Germany
| | - Carmen Osorio
- Brain Research Institute, Department of Neuropharmacology, University of Bremen, Hochschulring 18, 28359 Bremen, Germany
| | - Michael Koch
- Brain Research Institute, Department of Neuropharmacology, University of Bremen, Hochschulring 18, 28359 Bremen, Germany
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Pinnock F, Bosch D, Brown T, Simons N, Yeomans JR, DeOliveira C, Schmid S. Nicotine receptors mediating sensorimotor gating and its enhancement by systemic nicotine. Front Behav Neurosci 2015; 9:30. [PMID: 25717295 PMCID: PMC4324144 DOI: 10.3389/fnbeh.2015.00030] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2014] [Accepted: 01/28/2015] [Indexed: 12/02/2022] Open
Abstract
Prepulse inhibition (PPI) of startle occurs when intensity stimuli precede stronger startle-inducing stimuli by 10–1000 ms. PPI deficits are found in individuals with schizophrenia and other psychiatric disorders, and they correlate with other cognitive impairments. Animal research and clinical studies have demonstrated that both PPI and cognitive function can be enhanced by nicotine. PPI has been shown to be mediated, at least in part, by mesopontine cholinergic neurons that project to pontine startle neurons and activate muscarinic and potentially nicotine receptors (nAChRs). The subtypes and anatomical location of nAChRs involved in mediating and modulating PPI remain unresolved. We tested the hypothesis that nAChRs that are expressed by pontine startle neurons contribute to PPI. We also explored whether or not these pontine receptors are responsible for the nicotine enhancement of PPI. While systemic administration of nAChR antagonists had limited effects on PPI, PnC microinfusions of the non-α7nAChR preferring antagonist TMPH, but not of the α7nAChR antagonist MLA, into the PnC significantly reduced PPI. Electrophysiological recordings from startle-mediating PnC neurons confirmed that nicotine affects excitability of PnC neurons, which could be antagonized by TMPH, but not by MLA, indicating the expression of non-α7nAChR. In contrast, systemic nicotine enhancement of PPI was only reversed by systemic MLA and not by TMPH or local microinfusions of MLA into the PnC. In summary, our data indicate that non-α7nAChRs in the PnC contribute to PPI at stimulus intervals of 100 ms or less, whereas activation of α7nAChRs in other brain areas is responsible for the systemic nicotine enhancement of PPI. This is important knowledge for the correct interpretation of behavioral, preclinical, and clinical data as well as for developing drugs for the amelioration of PPI deficits and the enhancement of cognitive function.
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Affiliation(s)
- Farena Pinnock
- Anatomy and Cell Biology, Schulich School of Medicine and Dentistry, University of Western Ontario London, ON, Canada
| | - Daniel Bosch
- Department of Psychology, University of Toronto Toronto, ON, Canada ; Hertie Institute for Clinical Brain Research, Eberhard-Karls-Universität Tübingen, Germany
| | - Tyler Brown
- Anatomy and Cell Biology, Schulich School of Medicine and Dentistry, University of Western Ontario London, ON, Canada
| | - Nadine Simons
- Anatomy and Cell Biology, Schulich School of Medicine and Dentistry, University of Western Ontario London, ON, Canada
| | - John R Yeomans
- Department of Psychology, University of Toronto Toronto, ON, Canada
| | - Cleusa DeOliveira
- Anatomy and Cell Biology, Schulich School of Medicine and Dentistry, University of Western Ontario London, ON, Canada
| | - Susanne Schmid
- Anatomy and Cell Biology, Schulich School of Medicine and Dentistry, University of Western Ontario London, ON, Canada ; Department of Psychology, University of Toronto Toronto, ON, Canada
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11
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Foster DJ, Choi DL, Conn PJ, Rook JM. Activation of M1 and M4 muscarinic receptors as potential treatments for Alzheimer's disease and schizophrenia. Neuropsychiatr Dis Treat 2014; 10:183-91. [PMID: 24511233 PMCID: PMC3913542 DOI: 10.2147/ndt.s55104] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Alzheimer's disease (AD) and schizophrenia (SZ) are neurological disorders with overlapping symptomatology, including both cognitive deficits and behavioral disturbances. Current clinical treatments for both disorders have limited efficacy accompanied by dose-limiting side effects, and ultimately fail to adequately address the broad range of symptoms observed. Novel therapeutic options for AD and SZ are needed to better manage the spectrum of symptoms with reduced adverse-effect liability. Substantial evidence suggests that activation of muscarinic acetylcholine receptors (mAChRs) has the potential to treat both cognitive and psychosis-related symptoms associated with numerous central nervous system (CNS) disorders. However, use of nonselective modulators of mAChRs is hampered by dose-limiting peripheral side effects that limit their clinical utility. In order to maintain the clinical efficacy without the adverse-effect liability, efforts have been focused on the discovery of compounds that selectively modulate the centrally located M1 and M4 mAChR subtypes. Previous drug discovery attempts have been thwarted by the highly conserved nature of the acetylcholine site across mAChR subtypes. However, current efforts by our laboratory and others have now focused on modulators that bind to allosteric sites on mAChRs, allowing these compounds to display unprecedented subtype selectivity. Over the past couple of decades, the discovery of small molecules capable of selectively targeting the M1 or M4 mAChR subtypes has allowed researchers to elucidate the roles of these receptors in regulating cognitive and behavioral disturbances in preclinical animal models. Here, we provide an overview of these promising preclinical and clinical studies, which suggest that M1- and M4-selective modulators represent viable novel targets with the potential to successfully address a broad range of symptoms observed in patients with AD and SZ.
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Affiliation(s)
- Daniel J Foster
- Department of Pharmacology and Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Derrick L Choi
- Department of Pharmacology and Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University Medical Center, Nashville, TN, USA
| | - P Jeffrey Conn
- Department of Pharmacology and Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Jerri M Rook
- Department of Pharmacology and Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University Medical Center, Nashville, TN, USA
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12
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Koh HY. Phospholipase C-β1 and schizophrenia-related behaviors. Adv Biol Regul 2013; 53:242-248. [PMID: 24035496 DOI: 10.1016/j.jbior.2013.08.002] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2013] [Accepted: 08/11/2013] [Indexed: 06/02/2023]
Abstract
Abnormal expression patterns of phospholipase C-β1(PLC-β1) in specific brain areas of patients with schizophrenia, and its high genetic linkage to the disorder implicated a pathogenetical involvement of PLC-β1 signaling system. The schizophrenia-related behavioral phenotypes displayed in the mutant mice lacking PLC-β1 (PLC-β1 KO) suggested that PLCβ1-linked signaling pathways may be involved in the neural system whose function is disrupted in the pathogenesis of schizophrenia. In the brain, PLC-β1 is known to be linked to muscarinic acetylcholine receptors, metabotropic glutamatergic, serotonergic, and oxytocinergic systems. The objective of this review is to provide an overview of the current knowledge regarding these schizophrenia-related behaviors and discuss the probable ways in which PLC-β1signalling can be involved in the neural mechanisms for each behavior, which may help suggest future directions for research in this area.
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Affiliation(s)
- Hae-Young Koh
- Center for Neuroscience, Brain Science Institute, Korea Institute of Science and Technology, Hwarangno 14-gil 5, Seongbuk-gu, Seoul 136-791, South Korea.
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Bubser M, Byun N, Wood MR, Jones CK. Muscarinic receptor pharmacology and circuitry for the modulation of cognition. Handb Exp Pharmacol 2012:121-66. [PMID: 22222698 DOI: 10.1007/978-3-642-23274-9_7] [Citation(s) in RCA: 83] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
The muscarinic cholinergic system constitutes an important part of the neuronal circuitry that modulates normal cognition. Muscarinic receptor antagonists are well known to produce or exacerbate impairments in attention, learning, and memory. Conversely, both direct-acting muscarinic receptor agonists and indirect-acting muscarinic cholinergic agonists, such as acetylcholinesterase inhibitors, have shown cognition-enhancing properties, including improvements in normal cognitive function, reversal of cognitive deficits induced by muscarinic receptor antagonists, and attenuation of cognitive deficits in psychiatric and neurological disorders, such as Alzheimer's disease and schizophrenia. However, until recently, the lack of small molecule ligands that antagonize or activate specific muscarinic acetylcholine receptor (mAChR) subtypes with high selectivity has been a major obstacle in defining the relative contributions of individual mAChRs to different aspects of cognitive function and for the development of novel therapeutic agents. These limitations may be potentially overcome by the recent discovery of novel mAChR subtype-selective compounds, notably allosteric agonists and positive allosteric modulators, which exhibit greater selectivity for individual mAChR subtypes than previous mAChR orthosteric agonists. In preclinical studies, these novel ligands have shown promising efficacy in several models for the enhancement of cognition. In this chapter, we will review the muscarinic cholinergic circuitry and pharmacology of mAChR agonists and antagonists relevant to the modulation of different aspects of cognition in animals and clinical populations.
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Affiliation(s)
- Michael Bubser
- Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University, Nashville, TN 37232, USA
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Singer P, Yee BK. Reversal of scopolamine-induced disruption of prepulse inhibition by clozapine in mice. Pharmacol Biochem Behav 2011; 101:107-14. [PMID: 22210488 DOI: 10.1016/j.pbb.2011.12.010] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/02/2011] [Revised: 12/09/2011] [Accepted: 12/14/2011] [Indexed: 01/15/2023]
Abstract
Prepulse inhibition (PPI) of the acoustic startle reflex refers to the reduction of the startle response to an intense acoustic pulse stimulus when it is shortly preceded by a weak non-startling prepulse stimulus and provides a cross-species measure of sensory-motor gating. PPI is typically impaired in schizophrenia patients, and a similar impairment can be induced in rats by systemic scopolamine, a muscarinic cholinergic receptor antagonist that can evoke a range of cognitive and psychotic symptoms in healthy humans that are commonly referred to as the "anti-muscarinic syndrome" resembling some clinical features of schizophrenia. Scopolamine-induced PPI disruption has therefore been proposed as an anti-muscarinic animal model of schizophrenia, but parallel investigations in the mouse remain scant and the outcomes are mixed and often confounded by an elevation of startle reactivity. Here, we distinguished the PPI-disruptive and the confounding startle-enhancing effects of scopolamine (1 and 10mg/kg, i.p.) in C57BL/6 wild-type mice by showing that the latter partly stemmed from a shift in spontaneous baseline reactivity. With appropriate correction for between-group differences in startle reactivity, we went on to confirm that the PPI-disruptive effect of scopolamine could be nullified by clozapine pre-treatment (1.5mg/kg, i.p.) in a dose-dependent manner. This is the first demonstration that scopolamine-induced PPI disruption is sensitive to atypical antipsychotic drugs. In concert with previous data showing its sensitivity to haloperidol the present finding supports the predictive validity of the anti-muscarinic PPI disruption model for both typical and atypical antipsychotic drug action.
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Affiliation(s)
- Philipp Singer
- Laboratory of Behavioural Neurobiology, Swiss Federal Institute of Technology Zurich, Schorenstrasse 16, CH 8603 Schwerzenbach, Switzerland.
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Veeraragavan S, Graham D, Bui N, Yuva-Paylor LA, Wess J, Paylor R. Genetic reduction of muscarinic M4 receptor modulates analgesic response and acoustic startle response in a mouse model of fragile X syndrome (FXS). Behav Brain Res 2011; 228:1-8. [PMID: 22123412 DOI: 10.1016/j.bbr.2011.11.018] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2011] [Revised: 10/30/2011] [Accepted: 11/15/2011] [Indexed: 11/28/2022]
Abstract
INTRODUCTION The G-protein coupled muscarinic acetylcholine receptors, widely expressed in the CNS, have been implicated in fragile X syndrome (FXS). Recent studies have reported an overactive signaling through the muscarinic receptors in the Fmr1KO mouse model. Hence, it was hypothesized that reducing muscarinic signaling might modulate behavioral phenotypes in the Fmr1KO mice. Pharmacological studies from our lab have provided evidence for this hypothesis, with subtype-preferring muscarinic M1 and M4 receptor antagonists modulating select behaviors in the Fmr1KO mice. Since the pharmacological antagonists were not highly specific, we investigated the specific role of M4 receptors in the Fmr1KO mouse model, using a genetic approach. METHODS We created a double mutant heterozygous for the M4 receptor gene and hemizygous for the Fmr1 gene and examined the mutants on various behaviors. Each animal was tested on a behavior battery comprising of open-field activity (activity), light-dark (anxiety), marble burying (perseverative behavior), prepulse inhibition (sensorimotor gating), rotarod (motor coordination), passive avoidance (learning and memory) and hotplate (analgesia). Animals were also tested on the audiogenic seizure protocol and testis weights were measured. RESULTS Reduction of M4 receptor expression in the heterozygotes completely rescued the analgesic response and partly rescued the acoustic startle response phenotype in the Fmr1KO mice. However, no modulation was observed in a number of behaviors including learning and memory, activity, perseverative behavior and audiogenic seizures. CONCLUSION Reducing M4 receptor signaling altered only select behavioral phenotypes in the Fmr1KO mouse model, suggesting that other targets are involved in the modulation of fragile X behaviors.
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Affiliation(s)
- Surabi Veeraragavan
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA.
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Veeraragavan S, Bui N, Perkins JR, Yuva-Paylor LA, Paylor R. The modulation of fragile X behaviors by the muscarinic M4 antagonist, tropicamide. Behav Neurosci 2011; 125:783-90. [PMID: 21942438 PMCID: PMC3183989 DOI: 10.1037/a0025202] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Muscarinic acetylcholine receptors (mAChR) are G protein-coupled receptors (M1-M5), grouped together into two functional classes, based on their G protein interaction. Although ubiquitously expressed in the CNS, the M4 protein shows highest expression in the neostriatum, cortex, and hippocampus. Electrophysiological and biochemical studies have provided evidence for overactive mAChR signaling in the fragile X knock-out (Fmr1KO) mouse model, and this has been hypothesized to contribute to the phenotypes seen in Fmr1KO mice. To address this hypothesis we used an M4 antagonist, tropicamide, to reduce the activity through the M4 mAChR and investigated the behavioral response in the Fmr1KO animals. Data from the marble-burying assay have shown that tropicamide treatment resulted in a decreased number of marbles buried in the wild-type (WT) and in the knockout (KO) animals. Results from the open field assay indicated that tropicamide increases activity in both the WT and KO mice. In the passive avoidance assay, tropicamide treatment resulted in the improvement of performance in both the WT and the KO animals at the lower doses (2 and 5 mg/kg), and the drug was shown to be important for the acquisition and not the consolidation process. Lastly, we observed that tropicamide causes a significant decrease in the percentage of audiogenic seizures in the Fmr1KO animals. These results suggest that pharmacological antagonism of the M4 receptor modulates select behavioral responses in the Fmr1KO mice.
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Affiliation(s)
- Surabi Veeraragavan
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
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Ago Y, Koda K, Ota Y, Kita Y, Fukada A, Takuma K, Matsuda T. Donepezil, but not galantamine, blocks muscarinic receptor-mediated in vitro and in vivo responses. Synapse 2011; 65:1373-7. [PMID: 21780184 DOI: 10.1002/syn.20969] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2011] [Accepted: 07/15/2011] [Indexed: 12/15/2022]
Abstract
We have found that galantamine, but not donepezil, reversed isolation rearing-induced deficits of prepulse inhibition (PPI) via an activation of muscarinic M1 receptors. To explain this difference, the present study examined the effects of these acetylcholinesterase inhibitors on muscarinic receptor-mediated responses in in vitro and in vivo systems. Ca(2+) -imaging study showed that donepezil, but not galantamine, blocked a muscarinic agonist carbachol-induced increase in intracellular Ca(2+) levels in SH-SY5Y cells. Moreover, a microdialysis study showed that intraperitoneal administration of donepezil, but not galantamine, attenuated a preferential M1 receptor agonist Ndesmethylclozapine-induced increase in dopamine release in mouse cerebral cortex. These results suggest that donepezil, but not galantamine, has an ability to block muscarinic receptor function and imply that the differential effects may be responsible for the difference in the effects on isolation rearing-induced deficits of PPI between these drugs. Synapse, 2011. © 2011 Wiley-Liss, Inc.
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Affiliation(s)
- Yukio Ago
- Laboratory of Medicinal Pharmacology, Graduate School of Pharmaceutical Sciences, Osaka University, Suita, Osaka 565-871, Japan
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Koda K, Ago Y, Yano K, Nishimura M, Kobayashi H, Fukada A, Takuma K, Matsuda T. Involvement of decreased muscarinic receptor function in prepulse inhibition deficits in mice reared in social isolation. Br J Pharmacol 2011; 162:763-72. [PMID: 20958289 DOI: 10.1111/j.1476-5381.2010.01080.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
BACKGROUND AND PURPOSE We have previously reported that galantamine, a weak acetylcholinesterase inhibitor, improves prepulse inhibition (PPI) deficits in mice reared in social isolation. ACh receptors are involved in the underlying mechanism of PPI, but whether rearing in social isolation causes dysfunction of the cholinergic system is unknown. In this study, we examined the involvement of muscarinic receptors in the improvement of PPI deficits induced by galantamine, and whether the cholinergic system is altered in mice reared in isolation. EXPERIMENTAL APPROACH Three-week-old male ddY mice were housed in isolated cages for 6 weeks before the initiation of experiments to create PPI deficits. Cholinergic functions were determined by measuring the behavioural and neurochemical responses to nicotinic and muscarinic receptor agonists. KEY RESULTS The improvement by galantamine of social isolation-induced PPI deficits was blocked by scopolamine, a non-selective muscarinic antagonist, and telenzepine, a preferential M₁ receptor antagonist. Activation of M₁ receptors improved social isolation-induced PPI deficits. Social isolation did not affect choline acetyltransferase and acetylcholinesterase activities in the prefrontal cortex and hippocampus, but it reduced the locomotor-suppressive response to muscarinic agonist oxotremorine, but not to nicotine. The isolation also attenuated the M₁ receptor agonist N-desmethylclozapine-induced increase in prefrontal dopamine release. CONCLUSIONS AND IMPLICATIONS Galantamine improves PPI deficits of mice reared in social isolation via activation of M₁ receptors. Social isolation reduces the muscarinic, especially M₁, receptor function and this is involved in PPI deficits.
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Affiliation(s)
- K Koda
- Laboratory of Medicinal Pharmacology, Graduate School of Pharmaceutical Sciences, Osaka University, Yamada-oka, Suita, Osaka, Japan
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Robinson L, Platt B, Riedel G. Involvement of the cholinergic system in conditioning and perceptual memory. Behav Brain Res 2011; 221:443-65. [PMID: 21315109 DOI: 10.1016/j.bbr.2011.01.055] [Citation(s) in RCA: 82] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2011] [Accepted: 01/29/2011] [Indexed: 01/07/2023]
Abstract
The cholinergic systems play a pivotal role in learning and memory, and have been the centre of attention when it comes to diseases containing cognitive deficits. It is therefore not surprising, that the cholinergic transmitter system has experienced detailed examination of its role in numerous behavioural situations not least with the perspective that cognition may be rescued with appropriate cholinergic 'boosters'. Here we reviewed the literature on (i) cholinergic lesions, (ii) pharmacological intervention of muscarinic or nicotinic system, or (iii) genetic deletion of selective receptor subtypes with respect to sensory discrimination and conditioning procedures. We consider visual, auditory, olfactory and somatosensory processing first before discussing more complex tasks such as startle responses, latent inhibition, negative patterning, eye blink and fear conditioning, and passive avoidance paradigms. An overarching reoccurring theme is that lesions of the cholinergic projection neurones of the basal forebrain impact negatively on acquisition learning in these paradigms and blockade of muscarinic (and to a lesser extent nicotinic) receptors in the target structures produce similar behavioural deficits. While these pertain mainly to impairments in acquisition learning, some rare cases extend to memory consolidation. Such single case observations warranted replication and more in-depth studies. Intriguingly, receptor blockade or receptor gene knockout repeatedly produced contradictory results (for example in fear conditioning) and combined studies, in which genetically altered mice are pharmacological manipulated, are so far missing. However, they are desperately needed to clarify underlying reasons for these contradictions. Consistently, stimulation of either muscarinic (mainly M(1)) or nicotinic (predominantly α7) receptors was beneficial for learning and memory formation across all paradigms supporting the notion that research into the development and mechanisms of novel and better cholinomimetics may prove useful in the treatment of neurodegenerative or psychiatric disorders with cognitive endophenotypes.
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Affiliation(s)
- Lianne Robinson
- School of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, UK.
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Bitanihirwe BKY, Dubroqua S, Singer P, Feldon J, Yee BK. Sensorimotor gating and vigilance-dependent choice accuracy: a within-subject correlative analysis in wild-type C57BL/6 mice. Behav Brain Res 2010; 217:178-87. [PMID: 20974191 DOI: 10.1016/j.bbr.2010.10.021] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2010] [Revised: 10/07/2010] [Accepted: 10/17/2010] [Indexed: 11/28/2022]
Abstract
Deterioration in attention and related processes is an early sign in schizophrenia predictive of disease development. Amongst the various translational paradigms for assessing attention in rodents, it is not known if they are equivalent in detecting individual differences. Answers here are pertinent to their use in the general human population for identifying individuals at high risk of developing schizophrenia. The present study employed a within-subject approach to examine in mice two common paradigms for assessing attention that differ markedly in their implementation. An operant-based two-choice visual discrimination task (2-CVDT) that depends on effortful attention to brief visual cues was contrasted with prepulse inhibition (PPI) of the acoustic startle reflex, a well-established test of pre-attentive gating whereby processing of a startle-eliciting stimulus is inhibited by a preceding weak prepulse stimulus. Here, we revealed a correlation showing that individual mice with low PPI tended to perform poorly in the 2-CVDT in terms of choice accuracy but not response speed. This specific positive correlation suggests that the two readouts might be regulated via common attentional mechanisms, which might be critically dependent on normal muscarinic and N-methyl-d-asparate receptor functions. As demonstrated here, blockade of either receptor type by scopolamine or dizocilpine impaired 2-CVDT performance at doses that have been shown to disrupt PPI in mice. Further studies contrasting these two paradigms would be warranted to characterize the possible underlying psychological constructs that give rise to this correlation and to clarify whether the two paradigms may effectively capture schizophrenia-related cognitive deficits belonging to orthogonal domains.
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Affiliation(s)
- Byron K Y Bitanihirwe
- Laboratory of Behavioural Neurobiology, Swiss Federal Institute of Technology Zurich, Schwerzenbach, Switzerland
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Yeomans JS, Bosch D, Alves N, Daros A, Ure RJ, Schmid S. GABA receptors and prepulse inhibition of acoustic startle in mice and rats. Eur J Neurosci 2010; 31:2053-61. [DOI: 10.1111/j.1460-9568.2010.07236.x] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Modulation of prepulse inhibition through both M(1) and M (4) muscarinic receptors in mice. Psychopharmacology (Berl) 2010; 208:401-16. [PMID: 20013114 PMCID: PMC3895331 DOI: 10.1007/s00213-009-1740-z] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/07/2009] [Accepted: 11/17/2009] [Indexed: 12/11/2022]
Abstract
RATIONALE Muscarinic cholinergic M(1) and M(4) receptors may participate in schizophrenia's etiology and have been proposed as targets for antipsychotic medications. OBJECTIVE Here, we investigated the involvement of these receptors in behavioral measures pertinent to schizophrenia using knockout mice lacking M(1) receptors (M(1)-/-), M(4) receptors (M(4)-/-), or both (M(1)-/-M(4)-/-). METHODS We measured prepulse inhibition (PPI) of startle without drugs and after treatment with scopolamine (0.32-1.8 mg/kg), xanomeline (3.2 mg/kg), oxotremorine (0.032-0.1 mg/kg), clozapine (1.0-5.6 mg/kg), or haloperidol (0.32-3.2 mg/kg). RESULTS In female (but not male) mice, combined deletion of both M(1) and M(4) receptors decreased PPI relative to wild-type mice, while knockout of either receptor alone had no significant effect. Scopolamine disrupted PPI in wild-type and M(4)-/- mice, but not in female M(1)-/-M(4)-/- or female M(1)-/- mice. When administered before scopolamine, xanomeline restored PPI in wild-type mice and M(1)-/- mice, but not in M(4)-/- mice. In contrast, pretreatment with oxotremorine increased PPI regardless of genotype. Effects of clozapine and haloperidol on PPI were not hindered by either mutation. CONCLUSIONS Deletion of both M(1) and M(4) receptors can disrupt PPI, suggesting that (at least partially redundant) M(1) and M(4) receptor-dependent functions are involved in sensorimotor gating mechanisms. PPI-disrupting effects of muscarinic antagonists appeared dependent upon M(1) receptor blockade. Our data also suggest that xanomeline exerts antipsychotic-like effects mainly through M(4) receptor stimulation, while stimulation of non-M(1)/M(4) subtypes may also have antipsychotic potential. Finally, our results do not support a role of M(1)/M(4) receptors in mediating antipsychotic-like effects of clozapine.
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Turner J, Hughes LF, Toth LA. Sleep, activity, temperature and arousal responses of mice deficient for muscarinic receptor M2 or M4. Life Sci 2009; 86:158-69. [PMID: 19958780 DOI: 10.1016/j.lfs.2009.11.019] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2009] [Revised: 11/18/2009] [Accepted: 11/23/2009] [Indexed: 01/14/2023]
Abstract
AIMS The type 2 muscarinic receptor (M2R) differs from the other G-protein-coupled muscarinic receptor (type 4, or M4R) in tissue distribution and physiologic effects. We studied the impact of these receptors on sleep and arousal by using M2R and M4R knock-out (KO) mice. MAIN METHODS M2R and M4R KO and genetically intact mice were compared in terms of normal patterns of sleep, responses to sleep loss, infectious challenge and acoustic startle, and acoustic prepulse inhibition of startle (PPI). KEY FINDINGS Under basal conditions, M2R and M4R KO mice do not differ from the background strain or each other in the amount or diurnal pattern of sleep, locomotor activity, and body temperature. After enforced sleep loss, M2R KO mice, in contrast to the other two strains, show no rebound in slow-wave sleep (SWS) time, although their SWS is consolidated, and they show a greater rebound in time spent in REMS (rapid-eye-movement sleep) and REMS consolidation. During influenza infection, M2R KO mice, as compared with the other strains, show marked hypothermia and a less robust increase in SWS. During Candida albicans infection, M2R KO mice show a greater increase in SWS and a greater inflammatory response than do the other strains. M2R KO mice also show greater acoustic startle amplitude than does the background strain, although PPI was not different across the 3 strains over a range of stimulus intensities. SIGNIFICANCE Taken together, these findings support different roles for M2R and M4R in the modulation of sleep and arousal during homeostatic challenge.
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Affiliation(s)
- Jeremy Turner
- Department of Psychology, Illinois College Jacksonville, IL 62650, USA
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Usp46 is a quantitative trait gene regulating mouse immobile behavior in the tail suspension and forced swimming tests. Nat Genet 2009; 41:688-95. [PMID: 19465912 DOI: 10.1038/ng.344] [Citation(s) in RCA: 80] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2008] [Accepted: 02/02/2009] [Indexed: 11/09/2022]
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Betz AJ, Vontell R, Valenta J, Worden L, Sink KS, Font L, Correa M, Sager TN, Salamone JD. Effects of the adenosine A 2A antagonist KW 6002 (istradefylline) on pimozide-induced oral tremor and striatal c-Fos expression: comparisons with the muscarinic antagonist tropicamide. Neuroscience 2009; 163:97-108. [PMID: 19467297 DOI: 10.1016/j.neuroscience.2009.05.040] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2009] [Revised: 05/04/2009] [Accepted: 05/18/2009] [Indexed: 10/20/2022]
Abstract
Typical antipsychotic drugs, including haloperidol and pimozide, have been shown to produce parkinsonian motor effects such as akinesia and tremor. Furthermore, there is an antagonistic interaction between adenosine A(2A) and dopamine D(2) receptors in the basal ganglia, which is important for motor functions related to the production of parkinsonian symptoms. Several experiments were conducted to assess the effects of the selective adenosine A(2A) antagonist KW 6002 on both the motor and cellular effects of subchronic administration of pimozide. The motor test employed was tremulous jaw movements, which is used as a model of parkinsonian tremor. In addition, c-Fos expression in the ventrolateral neostriatum, which is the striatal area most associated with tremulous jaw movements, was used as a marker of striatal cell activity in animals that were tested in the behavioral experiments. Repeated administration of 1.0 mg/kg pimozide induced tremulous jaw movements and increased ventrolateral striatal c-Fos expression, while administration of 20.0 mg/kg of the atypical antipsychotic quetiapine did not. The tremulous jaw movements induced by pimozide were significantly reduced by co-administration of either the adenosine A(2A) antagonist KW 6002 or the muscarinic antagonist tropicamide. Pimozide-induced increases in ventrolateral striatal c-Fos expression were reduced by a behaviorally effective dose of KW 6002, but c-Fos expression in pimozide-treated rats was actually increased by tropicamide. These results indicate that two different drug manipulations that act to reduce tremulous jaw movements can have different effects on DA antagonist-induced c-Fos expression, suggesting that adenosine A(2A) antagonism and muscarinic receptor antagonism exert their motor effects by acting on different striatal circuits.
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Affiliation(s)
- A J Betz
- Department of Psychology, University of Connecticut, Storrs, CT 06269-1020, USA
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Using the MATRICS to guide development of a preclinical cognitive test battery for research in schizophrenia. Pharmacol Ther 2009; 122:150-202. [PMID: 19269307 DOI: 10.1016/j.pharmthera.2009.02.004] [Citation(s) in RCA: 257] [Impact Index Per Article: 17.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2009] [Accepted: 02/17/2009] [Indexed: 12/29/2022]
Abstract
Cognitive deficits in schizophrenia are among the core symptoms of the disease, correlate with functional outcome, and are not well treated with current antipsychotic therapies. In order to bring together academic, industrial, and governmental bodies to address this great 'unmet therapeutic need', the NIMH sponsored the Measurement and Treatment Research to Improve Cognition in Schizophrenia (MATRICS) initiative. Through careful factor analysis and consensus of expert opinion, MATRICS identified seven domains of cognition that are deficient in schizophrenia (attention/vigilance, working memory, reasoning and problem solving, processing speed, visual learning and memory, verbal learning and memory, and social cognition) and recommended a specific neuropsychological test battery to probe these domains. In order to move the field forward and outline an approach for translational research, there is a need for a "preclinical MATRICS" to develop a rodent test battery that is appropriate for drug development. In this review, we outline such an approach and review current rodent tasks that target these seven domains of cognition. The rodent tasks are discussed in terms of their validity for probing each cognitive domain as well as a brief overview of the pharmacology and manipulations relevant to schizophrenia for each task.
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Towards an animal model of an antipsychotic drug-resistant cognitive impairment in schizophrenia: scopolamine induces abnormally persistent latent inhibition, which can be reversed by cognitive enhancers but not by antipsychotic drugs. Int J Neuropsychopharmacol 2009; 12:227-41. [PMID: 18687163 DOI: 10.1017/s1461145708009176] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
Schizophrenia symptoms segregate into positive, negative and cognitive, which exhibit differential sensitivity to drugs. Recent efforts to identify treatments targeting cognitive impairments in schizophrenia have directed attention to the cholinergic system for its well documented role in cognition. Relatedly, muscarinic antagonists (e.g. scopolamine) produce an 'antimuscarinic syndrome', characterized by psychosis and cognitive impairments. Latent inhibition (LI) is the poorer conditioning to a stimulus resulting from its non-reinforced pre-exposure. LI indexes the ability to ignore irrelevant stimuli and aberrations of this capacity produced by pro-psychotic agents (e.g. amphetamine, MK-801) are used extensively to model attentional impairments in schizophrenia. We recently showed that LI was disrupted by scopolamine at low doses, and this was reversed by typical and atypical antipsychotic drugs (APDs) and the acetylcholinesterase inhibitor physostigmine. Here, at a higher dose (1.5 mg/kg), scopolamine produced an opposite pole of attentional impairment, namely, attentional perseveration, whereby scopolamine-treated rats persisted in expressing LI under strong conditioning that prevented LI expression in controls. Scopolamine-induced persistent LI was reversed by cholinergic and glycinergic cognitive enhancers (physostigmine and glycine) but was resistant to both typical and atypical APDs (haloperidol and clozapine). The latter sets scopolamine-induced persistent LI apart from scopolamine- and amphetamine-induced disrupted LI, which are reversed by both typical and atypical APDs, as well as from other cases of abnormally persistent LI including MK-801-induced persistent LI, which is reversed by atypical APDs. Thus, scopolamine-induced persistent LI may provide a pharmacological LI model for screening cognitive enhancers that are efficient for the treatment of APD-resistant cognitive impairments in schizophrenia.
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Varoli L, Andreani A, Burnelli S, Granaiola M, Leoni A, Locatelli A, Morigi R, Rambaldi M, Bedini A, Fazio N, Spampinato S. Diphenidol-related diamines as novel muscarinic M4 receptor antagonists. Bioorg Med Chem Lett 2008; 18:2972-6. [PMID: 18395442 DOI: 10.1016/j.bmcl.2008.03.061] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2008] [Revised: 03/19/2008] [Accepted: 03/20/2008] [Indexed: 10/22/2022]
Abstract
A series of hydrochloride derivatives 2a-9a and quaternary ammonium derivatives 3b-9b of diphenidol have been synthesized and characterized in receptor binding and cellular functional assays versus human muscarinic M(1)-M(5) receptors expressed in CHO cells. Compound 8b, a methiodide derivative with a bipiperidinyl moiety and a second diphenidol framework, showed a potent and selective M(4) activity as competitive antagonist. Moreover 8b, acting as an allosteric modulator, was able to retard the dissociation rate of [(3)H]-N-methylscopolamine from CHO-M(4) cell membranes exposed to atropine. Taken together, these data suggest that 8b might open new avenues to the discovery of novel multivalent antagonists for the muscarinic receptors.
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Affiliation(s)
- Lucilla Varoli
- Department of Pharmaceutical Sciences, University of Bologna, Via Belmeloro 6, I-40126 Bologna, Italy.
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Betz AJ, McLaughlin PJ, Burgos M, Weber SM, Salamone JD. The muscarinic receptor antagonist tropicamide suppresses tremulous jaw movements in a rodent model of parkinsonian tremor: possible role of M4 receptors. Psychopharmacology (Berl) 2007; 194:347-59. [PMID: 17594079 DOI: 10.1007/s00213-007-0844-6] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/12/2006] [Accepted: 05/30/2007] [Indexed: 11/25/2022]
Abstract
RATIONALE Nonselective muscarinic acetylcholine antagonists have been used for several years as antiparkinsonian drugs. However, there are at least five subtypes of muscarinic receptor (M1-5). Neostriatal M4 receptors have been implicated in aspects of motor function, and it has been suggested that M4 antagonists could be used as treatments for parkinsonism. OBJECTIVE Currently, there is a lack of highly selective M4 antagonists that readily penetrate the blood brain barrier. Thus, the present studies focused upon the effects of tropicamide, a muscarinic acetylcholine receptor antagonist with moderate binding selectivity for the M4 receptor subtype. MATERIALS AND METHODS Tremulous jaw movements were used as a model of parkinsonian tremor in these studies, and the effects of tropicamide were compared with those of the nonselective muscarinic antagonist atropine. RESULTS Tropicamide suppressed the tremulous jaw movements induced by the muscarinic agonist pilocarpine and the dopamine antagonist pimozide. Analysis of the dose-response curves indicated that tropicamide showed approximately the same potency as atropine for suppression of pilocarpine-induced jaw movements but was more potent than atropine on the suppression of pimozide-induced jaw movements. In contrast, atropine was more potent than tropicamide in terms of impairing performance on visual stimulus detection and delayed nonmatch-to-position tasks. CONCLUSIONS These studies demonstrate that tropicamide, which currently is used clinically for ophthalmic purposes, can exert actions that are consistent with antiparkinsonian effects. Moreover, the different pattern of effects shown by tropicamide compared to those of atropine on motor vs cognitive tasks could be due to the modest M4 selectivity shown by tropicamide.
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Affiliation(s)
- Adrienne J Betz
- Behavioral Neuroscience, Department of Psychology, University of Connecticut, Storrs, CT 06269-1020, USA
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Andrus AK, Marable BR, Dunbar GL, Reilly MP, Maurissen JPJ. Effects of intensity and type of prepulse stimulus on prepulse inhibition in scopolamine treated rats. Pharmacol Biochem Behav 2007; 87:481-8. [PMID: 17669478 DOI: 10.1016/j.pbb.2007.06.004] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/27/2006] [Revised: 06/15/2007] [Accepted: 06/18/2007] [Indexed: 10/23/2022]
Abstract
Prepulse inhibition (PPI) of the auditory startle response (ASR) is a behavioral test that has been used to measure auditory thresholds, to assess sensory-motor integration functions, and its use has been recommended in the United States Environmental Protection Agency Developmental Neurotoxicity Guideline (OPPTS 870.6300). The purpose of the present study was to determine to what extent the intensity and/or type of prepulse stimuli modulate PPI in scopolamine-treated rats. The PPI of the ASR peak amplitude was measured when the intensity of a 10-kHz prepulse tone was varied (69-, 80-, and 90 dB[A]; Experiment 1) and when both the intensity and type of auditory prepulse (a 10-kHz tone vs. a white noise burst) were varied (Experiment 2). Scopolamine treatment attenuated PPI in both experiments and interacted significantly with the prepulse stimulus intensity in Experiment 1. In Experiment 2, the percent of PPI was linearly related to prepulse stimulus intensity for trials using a tone, but was biphasic on trials using a white-noise prepulse stimulus. Prepulse stimuli of certain intensities elicited a response, and this response was greater when the prepulse stimulus was a white noise burst versus a tone of the same intensity. Further, the response to the prepulse altered the amount of inhibition and, therefore, confounded the overall measure of PPI at the higher prepulse stimulus intensity levels. Overall, these results indicate that careful consideration of the intensity and type of prepulse stimuli be taken in the context of their potential to induce a prepulse-elicited response, as well as providing the appropriate measures of such a response, when designing and interpreting PPI experiments.
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Affiliation(s)
- Amanda K Andrus
- Toxicology & Environmental Research and Consulting, The Dow Chemical Company, Midland, Michigan 48674, USA.
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5-HT6 receptor antagonist reversal of emotional learning and prepulse inhibition deficits induced by apomorphine or scopolamine. Pharmacol Biochem Behav 2007; 88:291-8. [PMID: 17920665 DOI: 10.1016/j.pbb.2007.08.015] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/21/2006] [Revised: 08/09/2007] [Accepted: 08/25/2007] [Indexed: 11/23/2022]
Abstract
5-HT6 receptors have been implicated in consolidation of visuospatial and reward-based learning tasks. Since 5-HT6 receptors may be important in modulation of sensory gating which is often affected in schizophrenic patients, we tested whether Ro 4368554, a 5-HT6 selective antagonist at a dose of 10 mg/kg, could reverse the loss of prepulse inhibition from apomorphine or scopolamine. In addition, we also tested whether Ro 4368554 altered fear conditioning using fear potentiated startle, a model for emotional learning. Prepulse inhibition of startle was disrupted by apomorphine (0.5 mg/kg) when prepulse emissions were 5 dB above background but not above 15 dB, while scopolamine (0.5 mg/kg) caused disruption at both prepulse levels. Scopolamine-mediated disruption was not reversed by Ro 4368854 but apomorphine-mediated disruption was significantly ameliorated by 5-HT6 inhibition. For fear potentiated startle, scopolamine and/or Ro 4368554 were administered before two daily fear conditioning sessions; rats were tested on the following day. Rats that received scopolamine displayed no fear potentiated startle but Ro 4368554 reversed this scopolamine deficit. Additionally, we mapped Fos induction in rats treated with scopolamine and/or Ro 4368554; scopolamine increased Fos expression in the central nucleus of the amygdala and this was attenuated by Ro 4368554. In summary, we have demonstrated the efficacy of 5-HT6 antagonists in modulating sensory gating and fear conditioning, and thus may be of therapeutic use for schizophrenia-related disorders.
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Barak S, Weiner I. Scopolamine induces disruption of latent inhibition which is prevented by antipsychotic drugs and an acetylcholinesterase inhibitor. Neuropsychopharmacology 2007; 32:989-99. [PMID: 16971898 DOI: 10.1038/sj.npp.1301208] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The fact that muscarinic antagonists may evoke a psychotic state ('antimuscarinic psychosis'), along with findings of cholinergic alterations in schizophrenia, have kindled an interest in the involvement of the cholinergic system in this disorder. Latent inhibition (LI) is a cross-species phenomenon manifested as a poorer conditioning of a stimulus seen when the stage of conditioning is preceded by a stage of repeated nonreinforced pre-exposure to that stimulus, and is considered to index the capacity to ignore irrelevant stimuli. Amphetamine-induced LI disruption and its reversal by antipsychotic drugs (APDs) is a well-established model of positive symptoms of schizophrenia. Here, we tested whether the muscarinic antagonist scopolamine would disrupt LI and whether such disruption would be reversed by APDs and by the acetylcholinesterase inhibitor physostigmine. The results showed that scopolamine at doses of 0.15 and 0.5 mg/kg disrupted LI, and that this effect was due to the action of the drug in the pre-exposure stage, suggesting a role of muscarinic transmission in attentional processes underlying LI. Both the typical and the atypical APDs, haloperidol and clozapine, reversed scopolamine-induced LI disruption when given in conditioning or in both stages, but not in pre-exposure, indicating that the mechanism of antipsychotic action in this model is independent of the mechanism of action of the propsychotic drug. Scopolamine-induced LI disruption was reversed by physostigmine (0.05 and 0.15 mg/kg), which was ineffective in reversing amphetamine-induced LI disruption, pointing to distinct mechanisms underlying LI disruption by these two propsychotic drugs. The latter was further supported by the finding that unlike amphetamine, the LI-disrupting doses of scopolamine did not affect activity levels. We propose scopolamine-induced LI disruption as a model of cholinergic-related positive symptoms in schizophrenia.
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Affiliation(s)
- Segev Barak
- Department of Psychology, Tel-Aviv University, Tel-Aviv, Israel
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Bosch D, Schmid S. Activation of muscarinic cholinergic receptors inhibits giant neurones in the caudal pontine reticular nucleus. Eur J Neurosci 2006; 24:1967-75. [PMID: 17040474 DOI: 10.1111/j.1460-9568.2006.05085.x] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Giant neurones in the caudal pontine reticular nucleus (PnC) play a crucial role in mediating the mammalian startle response. They receive input from cochlear, trigeminal and vestibular nuclei and project directly to motoneurones. Furthermore, they integrate modulatory input from different brain regions either enhancing or inhibiting startle responses. One prominent startle modulation is prepulse inhibition where a non-startling stimulus presented prior to the startle stimulus inhibits a subsequent startle response. Several behavioural studies have indicated that this inhibition is mediated by muscarinic receptors at the level of the PnC. Here, we performed whole-cell patch-clamp recordings from PnC giant neurones in acute rat brain slices in order to examine muscarinic inhibition. We stimulated afferent trigeminal and auditory fibres and applied muscarinic agonists and antagonists in order to investigate their effect on excitatory postsynaptic current amplitudes, paired-pulse ratio and passive membrane properties of PnC giant neurones. The cholinergic agonist carbachol and the muscarinic agonist oxotremorine significantly reduced excitatory postsynaptic current amplitudes and increased the paired-pulse ratio. Carbachol additionally reduced the membrane resistance of postsynaptic PnC giant neurones. The subtype-specific antagonists AF-DX116 (M2 preferring) and tropicamide (M4 preferring) antagonized the oxotremorine effect indicating that M4 and possibly M2 receptor subtypes are involved in this inhibition. The G-protein-activated inward rectifying potassium channel blocker tertiapin-Q had no effect on oxotremorine-induced inhibition of giant neurones. Our results show a mainly presynaptically mediated strong inhibition of PnC giant neurones by activation of M4 and possibly M2 receptors that presumably contribute to prepulse inhibition.
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Affiliation(s)
- Daniel Bosch
- Tierphysiologie, Zoologisches Institut, Fakultät für Biologie, Universität Tübingen, Germany
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