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Román V, Kedves R, Kelemen K, Némethy Z, Sperlágh B, Lendvai B, Vizi ES. Contribution of analog signaling to neurotransmitter interactions and behavior: Role of transporter-mediated nonquantal dopamine release. Physiol Rep 2021; 9:e15088. [PMID: 34762352 PMCID: PMC8582292 DOI: 10.14814/phy2.15088] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Revised: 09/28/2021] [Accepted: 10/08/2021] [Indexed: 11/28/2022] Open
Abstract
Neuronal networks cause changes in behaviorally important information processing through the vesicular release of neurotransmitters governed by the rate and timing of action potentials (APs). Herein, we provide evidence that dopamine (DA), nonquantally released from the cytoplasm, may exert similar effects in vivo. In mouse slice preparations, (+/-)-3,4-methylenedioxy-methamphetamine (MDMA, or ecstasy) and β-phenylethylamine (β-PEA)-induced DA release in the striatum and nucleus accumbens (NAc), two regions of the brain involved in reward-driven and social behavior and inhibited the axonal stimulation-induced release of tritiated acetylcholine ([3 H]ACh) in the striatum. The DA transporter (DAT) inhibitor (GBR-12909) prevented MDMA and β-PEA from causing DA release. GBR-12909 could also restore some of the stimulated acetylcholine release reduced by MDMA or β-PEA in the striatum confirming the fundamental role of DAT. In addition, hypothermia could prevent the β-PEA-induced release in the striatum and in the NAc. Sulpiride, a D2 receptor antagonist, also prevented the inhibitory effects of MDMA or β-PEA on stimulated ACh release, suggesting they act indirectly via binding of DA. Reflecting the neurochemical interactions in brain slices at higher system level, MDMA altered the social behavior of rats by preferentially enhancing passive social behavior. Similar to the in vitro effects, GBR-12909 treatment reversed specific elements of the MDMA-induced changes in behavior, such as passive social behavior, while left others including social play unchanged. The changes in behavior by the high level of extracellular DA-- a significant amount originating from cytoplasmic release--suggest that in addition to digital computation through synapses, the brain also uses analog communication, such as DA signaling, to mediate some elements of complex behaviors, but in a much longer time scale.
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Affiliation(s)
- Viktor Román
- Pharmacology and Drug Safety ResearchGedeon Richter Plc.BudapestHungary
| | - Rita Kedves
- Pharmacology and Drug Safety ResearchGedeon Richter Plc.BudapestHungary
| | - Kristóf Kelemen
- Pharmacology and Drug Safety ResearchGedeon Richter Plc.BudapestHungary
| | - Zsolt Némethy
- Pharmacology and Drug Safety ResearchGedeon Richter Plc.BudapestHungary
| | | | - Balázs Lendvai
- Pharmacology and Drug Safety ResearchGedeon Richter Plc.BudapestHungary
| | - E. Sylvester Vizi
- Institute of Experimental MedicineBudapestHungary
- Department of Pharmacology and PharmacotherapySemmelweis UniversityBudapestHungary
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Pharmacological modulation of AMPA receptor phosphorylation by dopamine and muscarinic receptor agents in the rat medial prefrontal cortex. Eur J Pharmacol 2018; 820:45-52. [DOI: 10.1016/j.ejphar.2017.12.022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2017] [Revised: 12/06/2017] [Accepted: 12/08/2017] [Indexed: 11/24/2022]
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3
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Qi Z, Yu GP, Tretter F, Pogarell O, Grace AA, Voit EO. A heuristic model for working memory deficit in schizophrenia. BIOCHIMICA ET BIOPHYSICA ACTA 2016; 1860:2696-705. [PMID: 27177811 PMCID: PMC5018429 DOI: 10.1016/j.bbagen.2016.04.031] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/03/2016] [Revised: 03/26/2016] [Accepted: 04/29/2016] [Indexed: 12/16/2022]
Abstract
BACKGROUND The life of schizophrenia patients is severely affected by deficits in working memory. In various brain regions, the reciprocal interactions between excitatory glutamatergic neurons and inhibitory GABAergic neurons are crucial. Other neurotransmitters, in particular dopamine, serotonin, acetylcholine, and norepinephrine, modulate the local balance between glutamate and GABA and therefore regulate the function of brain regions. Persistent alterations in the balances between the neurotransmitters can result in working memory deficits. METHODS Here we present a heuristic computational model that accounts for interactions among neurotransmitters across various brain regions. The model is based on the concept of a neurochemical interaction matrix at the biochemical level and combines this matrix with a mobile model representing physiological dynamic balances among neurotransmitter systems associated with working memory. RESULTS The comparison of clinical and simulation results demonstrates that the model output is qualitatively very consistent with the available data. In addition, the model captured how perturbations migrated through different neurotransmitters and brain regions. Results showed that chronic administration of ketamine can cause a variety of imbalances, and application of an antagonist of the D2 receptor in PFC can also induce imbalances but in a very different manner. CONCLUSIONS The heuristic computational model permits a variety of assessments of genetic, biochemical, and pharmacological perturbations and serves as an intuitive tool for explaining clinical and biological observations. GENERAL SIGNIFICANCE The heuristic model is more intuitive than biophysically detailed models. It can serve as an important tool for interdisciplinary communication and even for psychiatric education of patients and relatives. This article is part of a Special Issue entitled "System Genetics" Guest Editor: Dr. Yudong Cai and Dr. Tao Huang.
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Affiliation(s)
- Zhen Qi
- Department of Biomedical Engineering, Georgia Institute of Technology and Emory University School of Medicine, Atlanta, GA 30332, USA; Integrative BioSystems Institute, Georgia Institute of Technology, Atlanta, GA 30332, USA.
| | - Gina P Yu
- Department of Biomedical Engineering, Georgia Institute of Technology and Emory University School of Medicine, Atlanta, GA 30332, USA
| | - Felix Tretter
- Bertalanffy Center for the Study of Systems Science, 1040 Vienna, Austria
| | | | - Anthony A Grace
- Department of Neuroscience, Psychiatry and Psychology, University of Pittsburgh, 456 Langley Hall, Pittsburgh, PA, USA
| | - Eberhard O Voit
- Department of Biomedical Engineering, Georgia Institute of Technology and Emory University School of Medicine, Atlanta, GA 30332, USA; Integrative BioSystems Institute, Georgia Institute of Technology, Atlanta, GA 30332, USA
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Xue B, Fitzgerald CA, Jin DZ, Mao LM, Wang JQ. Amphetamine elevates phosphorylation of eukaryotic initiation factor 2α (eIF2α) in the rat forebrain via activating dopamine D1 and D2 receptors. Brain Res 2016; 1646:459-466. [PMID: 27338925 DOI: 10.1016/j.brainres.2016.06.027] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2015] [Revised: 06/16/2016] [Accepted: 06/18/2016] [Indexed: 10/21/2022]
Abstract
Psychostimulants have an impact on protein synthesis, although underlying molecular mechanisms are unclear. Eukaryotic initiation factor 2α-subunit (eIF2α) is a key player in initiation of protein translation and is regulated by phosphorylation. While this factor is sensitive to changing synaptic input and is critical for synaptic plasticity, its sensitivity to stimulants is poorly understood. Here we systematically characterized responses of eIF2α to a systemic administration of the stimulant amphetamine (AMPH) in dopamine responsive regions of adult rat brains. Intraperitoneal injection of AMPH at 5mg/kg increased eIF2α phosphorylation at serine 51 in the striatum. This increase was transient. In the medial prefrontal cortex (mPFC), AMPH induced a relatively delayed phosphorylation of the factor. Pretreatment with a dopamine D1 receptor antagonist SCH23390 blocked the AMPH-stimulated eIF2α phosphorylation in both the striatum and mPFC. Similarly, a dopamine D2 receptor antagonist eticlopride reduced the effect of AMPH in the two regions. Two antagonists alone did not alter basal eIF2α phosphorylation. AMPH and two antagonists did not change the amount of total eIF2α proteins in both regions. These results demonstrate the sensitivity of eIF2α to stimulant exposure. AMPH possesses the ability to stimulate eIF2α phosphorylation in striatal and mPFC neurons in vivo in a D1 and D2 receptor-dependent manner.
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Affiliation(s)
- Bing Xue
- Department of Basic Medical Science, School of Medicine, University of Missouri-Kansas City, MO 64108, USA
| | - Cole A Fitzgerald
- Department of Anesthesiology, School of Medicine, University of Missouri-Kansas City, Kansas City, MO 64108, USA
| | - Dao-Zhong Jin
- Department of Basic Medical Science, School of Medicine, University of Missouri-Kansas City, MO 64108, USA
| | - Li-Min Mao
- Department of Basic Medical Science, School of Medicine, University of Missouri-Kansas City, MO 64108, USA
| | - John Q Wang
- Department of Basic Medical Science, School of Medicine, University of Missouri-Kansas City, MO 64108, USA; Department of Anesthesiology, School of Medicine, University of Missouri-Kansas City, Kansas City, MO 64108, USA.
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Popescu M, Hughes JD, Popescu EA, Riedy G, DeGraba TJ. Reduced prefrontal MEG alpha-band power in mild traumatic brain injury with associated posttraumatic stress disorder symptoms. Clin Neurophysiol 2016; 127:3075-3085. [PMID: 27472543 DOI: 10.1016/j.clinph.2016.06.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2016] [Revised: 06/01/2016] [Accepted: 06/03/2016] [Indexed: 02/06/2023]
Abstract
OBJECTIVE To determine if changes in cortical alpha-band power in patients with mild traumatic brain injury (mTBI) are associated with the severity of their post-traumatic stress disorder (PTSD) symptoms, and if injury severity and level of exposure to psychologically traumatic events are predictors of these electrophysiological changes. METHODS Resting-state magnetoencephalographic recordings were analyzed in 32 patients with mTBI. Alpha-band power was estimated for each patient in 68 cortical regions and was compared between groups of patients with low versus high PTSD symptoms severity. RESULTS Participants with high PTSD symptom severity showed reduced alpha-band power bilaterally in the superior and middle frontal gyri and frontal poles, and in the left inferior frontal gyrus. Alpha-band power in bilateral middle frontal gyri and frontal poles was negatively correlated with scores reflecting symptoms of emotional numbing. Loss of consciousness (LOC) associated with mTBI and level of exposure to psychologically traumatic events were predictors of decreased prefrontal alpha-band power in some of these regions. CONCLUSION Altered prefrontal alpha-band activity, shown to be partly explained by mTBI-related LOC, is associated with PTSD symptoms severity. SIGNIFICANCE Our findings will guide future studies addressing the electrophysiological mechanisms underlying a higher incidence of PTSD in patients with mTBI.
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Affiliation(s)
- Mihai Popescu
- National Intrepid Center of Excellence, Walter Reed National Military Medical Center, Bethesda, MD, USA
| | - John D Hughes
- National Intrepid Center of Excellence, Walter Reed National Military Medical Center, Bethesda, MD, USA; Department of NeuroTrauma, Naval Medical Research Center, Silver Spring, MD, USA.
| | - Elena-Anda Popescu
- National Intrepid Center of Excellence, Walter Reed National Military Medical Center, Bethesda, MD, USA
| | - Gerard Riedy
- National Intrepid Center of Excellence, Walter Reed National Military Medical Center, Bethesda, MD, USA
| | - Thomas J DeGraba
- National Intrepid Center of Excellence, Walter Reed National Military Medical Center, Bethesda, MD, USA
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Xue B, Chen EC, He N, Jin DZ, Mao LM, Wang JQ. Integrated regulation of AMPA glutamate receptor phosphorylation in the striatum by dopamine and acetylcholine. Neuropharmacology 2016; 112:57-65. [PMID: 27060412 DOI: 10.1016/j.neuropharm.2016.04.005] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2015] [Revised: 04/01/2016] [Accepted: 04/05/2016] [Indexed: 12/16/2022]
Abstract
Dopamine (DA) and acetylcholine (ACh) signals converge onto protein kinase A (PKA) in medium spiny neurons of the striatum to control cellular and synaptic activities of these neurons, although underlying molecular mechanisms are less clear. Here we measured phosphorylation of the α-amino-3-hydroxy-5-methylisoxazole-4-propionic acid receptor (AMPAR) at a PKA site (S845) as an indicator of AMPAR responses in adult rat brains in vivo to explore how DA and ACh interact to modulate AMPARs. We found that subtype-selective activation of DA D1 receptors (D1Rs), D2 receptors (D2Rs), or muscarinic M4 receptors (M4Rs) induced specific patterns of GluA1 S845 responses in the striatum. These defined patterns support a local multitransmitter interaction model in which D2Rs inhibited an intrinsic inhibitory element mediated by M4Rs to enhance the D1R efficacy in modulating AMPARs. Consistent with this, selective enhancement of M4R activity by a positive allosteric modulator resumed the cholinergic inhibition of D1Rs. In addition, D1R and D2R coactivation recruited GluA1 and PKA preferentially to extrasynaptic sites. In sum, our in vivo data support an existence of a dynamic DA-ACh balance in the striatum which actively modulates GluA1 AMPAR phosphorylation and trafficking. This article is part of the Special Issue entitled 'Ionotropic glutamate receptors'.
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Affiliation(s)
- Bing Xue
- Department of Basic Medical Science, School of Medicine, University of Missouri-Kansas City, Kansas City, MO 64108, USA
| | - Elton C Chen
- Department of Anesthesiology, School of Medicine, University of Missouri-Kansas City, Kansas City, MO 64108, USA
| | - Nan He
- Department of Basic Medical Science, School of Medicine, University of Missouri-Kansas City, Kansas City, MO 64108, USA
| | - Dao-Zhong Jin
- Department of Basic Medical Science, School of Medicine, University of Missouri-Kansas City, Kansas City, MO 64108, USA
| | - Li-Min Mao
- Department of Basic Medical Science, School of Medicine, University of Missouri-Kansas City, Kansas City, MO 64108, USA
| | - John Q Wang
- Department of Basic Medical Science, School of Medicine, University of Missouri-Kansas City, Kansas City, MO 64108, USA; Department of Anesthesiology, School of Medicine, University of Missouri-Kansas City, Kansas City, MO 64108, USA; Beijing Institute of Brain Disorders, Capital Medical University, Beijing, China.
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7
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Dopamine differently modulates central cholinergic circuits in patients with Alzheimer disease and CADASIL. J Neural Transm (Vienna) 2014; 121:1313-20. [DOI: 10.1007/s00702-014-1195-1] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2013] [Accepted: 03/10/2014] [Indexed: 11/25/2022]
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Ladas A, Frantzidis C, Bamidis P, Vivas AB. Eye Blink Rate as a biological marker of Mild Cognitive Impairment. Int J Psychophysiol 2013; 93:12-6. [PMID: 23912068 DOI: 10.1016/j.ijpsycho.2013.07.010] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2012] [Revised: 07/01/2013] [Accepted: 07/25/2013] [Indexed: 02/03/2023]
Abstract
We investigated the relationship between dopamine activity (DA), as measured by Eye Blink Rate (EBR), and cognitive function in old adults with Mild Cognitive Impairment (MCI) and healthy controls. Research has been inconclusive so far about the factors responsible for the transition from MCI to dementia. However, some studies suggest that cortical hyperexcitability in very early stages of pathological aging may progressively lead to cell death, and thus to Alzheimer's disease. Hence, we speculated that a dysfunction of DA activity, as measured by EBR, may characterize people with MCI, and account for their poor cognitive function. Thirty three (33) healthy and thirty six (36) old adults with MCI (Mean age = 67.52 y.o.) participated in this study. The EBR was recorded under resting conditions, using two gold skin electrodes above and below the left eye. Cognitive function was assessed with a battery of neuropsychological tests. Participants with MCI showed significantly higher EBR than the healthy controls. Also, EBR was negatively related to scores on the Montreal Cognitive Assessment test (MoCA) test. We propose that abnormally increased dopamine activity, as indexed by relatively high EBR, may be partially responsible for the neurotransmitter imbalance in the central nervous system of people with MCI, and the overall impaired cognitive performance. In addition, this finding suggests that an abnormally high EBR may be a potential biomarker of the transition from healthy aging to dementia.
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Affiliation(s)
- Aristea Ladas
- Psychology Dept., The University of Sheffield International Faculty, City College, and South East European Research Center, SEERC, Thessaloniki, Greece
| | - Christos Frantzidis
- Dept of Medicine, School of Health Sciences, Aristotle University of Thessaloniki, Greece
| | - Panagiotis Bamidis
- Dept of Medicine, School of Health Sciences, Aristotle University of Thessaloniki, Greece
| | - Ana B Vivas
- Psychology Dept., The University of Sheffield International Faculty, City College, and South East European Research Center, SEERC, Thessaloniki, Greece.
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Martorana A, Di Lorenzo F, Esposito Z, Lo Giudice T, Bernardi G, Caltagirone C, Koch G. Dopamine D2-agonist Rotigotine effects on cortical excitability and central cholinergic transmission in Alzheimer's disease patients. Neuropharmacology 2013; 64:108-13. [DOI: 10.1016/j.neuropharm.2012.07.015] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2012] [Revised: 07/06/2012] [Accepted: 07/08/2012] [Indexed: 11/27/2022]
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Transient inactivation of the neonatal ventral hippocampus impairs attentional set-shifting behavior: reversal with an α7 nicotinic agonist. Neuropsychopharmacology 2012; 37:2476-86. [PMID: 22781844 PMCID: PMC3442342 DOI: 10.1038/npp.2012.106] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Cognitive deficits represent a core symptom cluster in schizophrenia that are thought to reflect developmental dysregulations within a neural system involving the ventral hippocampus (VH), nucleus accumbens (NAC), and prefrontal cortex (PFC). The present experiments determined the cognitive effects of transiently inactivating VH in rats during a sensitive period of development. Neonatal (postnatal day 7, PD7) and adolescent (PD32) male rats received a single bilateral infusion of saline or tetrodotoxin (TTX) within the VH to transiently inactivate local circuitry and efferent outflow. Rats were tested as adults on an attentional set-shifting task. Performance in this task depends upon the integrity of the PFC and NAC. TTX infusions did not affect the initial acquisition or ability to learn an intra-dimensional shift. However, TTX rats required a greater number of trials than did controls to acquire the first reversal and extra-dimensional shift (ED) stages. These impairments were age and region-specific as rats infused with TTX into the VH at PD32, or into the dorsal hippocampus at PD7, exhibited performance in the task similar to that of controls. Finally, acute systemic administration of the partial α7 nicotinic acetylcholine receptor (nAChR) agonist SSR 180711 (3.0 mg/kg) eliminated the TTX-induced performance deficits. Given that patients with schizophrenia exhibit hippocampal pathophysiology and deficits in the ED stages of set-shifting tasks, our results support the significance of transient hippocampal inactivation as an animal model for studying the cognitive impairments in schizophrenia as well as the pro-cognitive therapeutic potential of α7 nAChR agonists.
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Transient inactivation of the neonatal ventral hippocampus permanently disrupts the mesolimbic regulation of prefrontal cholinergic transmission: implications for schizophrenia. Neuropsychopharmacology 2011; 36:2477-87. [PMID: 21814184 PMCID: PMC3194075 DOI: 10.1038/npp.2011.136] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
These experiments determined the mesolimbic modulation of cortical cholinergic transmission in a neurodevelopmental model of schizophrenia. Mesolimbic-cholinergic abnormalities are hypothesized to contribute to the cognitive deficits seen in schizophrenia. Stimulation of NMDA receptors in nucleus accumbens (NAC) increases acetylcholine (ACh) release in the prefrontal cortex (PFC), a mechanism recently demonstrated to contribute to the control of attentional performance. We determined the ability of intra-NAC administration of NMDA to increase prefrontal ACh levels in adult rats that had received bilateral infusions of tetrodotoxin (TTX) to transiently interrupt impulse flow in the ventral hippocampus (VH) during development. Rats received infusions of TTX or saline on postnatal day 7 (PD7) or day 32 (PD32), and the effects of NAC NMDA receptor stimulation on prefrontal cholinergic neurotransmission were assessed in adulthood. In animals treated as controls on PD7, NMDA increased prefrontal ACh levels by 121% above baseline. In contrast, PD7 infusions of TTX into the VH abolished the ability of NAC NMDA to activate prefrontal cholinergic neurotransmission (7% increase). In animals that received TTX infusions on PD32, NMDA-evoked cholinergic activity did not differ from controls, indicating a restricted, neonatal critical period during which VH TTX impacts the organization of mesolimbic-basal forebrain-cortical circuitry. Importantly, the failure of NAC NMDA to evoke cholinergic activity in rats treated with TTX on PD7 did not reflect a reduced excitability of corticopetal cholinergic neurons because administration of amphetamine produced similar elevations of prefrontal ACh levels in PD7 TTX and PD7 control animals. A third series of experiments demonstrated that the effects of PD7 TTX are a specific consequence of transient disruption of impulse flow in the VH. Intra-NAC NMDA evoked prefrontal ACh release in rats receiving TTX, on PD7, into the dorsal hippocampus (DH), basolateral amygdala, or NAC. Thus, impulse flow specifically within the VH, during a sensitive period of development, is necessary for the functional organization of a mesolimbic-cortical circuit known to mediate attentional control processes. Therefore, neonatal inactivation of VH represents an effective animal model for studying the basis of certain cognitive symptoms of schizophrenia.
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Enhanced control of attention by stimulating mesolimbic-corticopetal cholinergic circuitry. J Neurosci 2011; 31:9760-71. [PMID: 21715641 DOI: 10.1523/jneurosci.1902-11.2011] [Citation(s) in RCA: 111] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Sustaining and recovering attentional performance requires interactions between the brain's motivation and attention systems. The first experiment demonstrated that in rats performing a sustained attention task (SAT), presentation of a distractor (dSAT) augmented performance-associated increases in cholinergic neurotransmission in prefrontal cortex. Because stimulation of NMDA receptors in the shell of the nucleus accumbens activates PFC cholinergic neurotransmission, a second experiment demonstrated that bilateral infusions of NMDA into the NAc shell, but not core, improved dSAT performance to levels observed in the absence of a distractor. A third experiment demonstrated that removal of prefrontal or posterior parietal cholinergic inputs, by intracortical infusions of the cholinotoxin 192 IgG-saporin, attenuated the beneficial effects of NMDA on dSAT performance. Mesolimbic activation of cholinergic projections to the cortex benefits the cognitive control of attentional performance by enhancing the detection of cues and the filtering of distractors.
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Tonic and phasic release of glutamate and acetylcholine neurotransmission in sub-regions of the rat prefrontal cortex using enzyme-based microelectrode arrays. J Neurosci Methods 2011; 202:199-208. [PMID: 21896284 DOI: 10.1016/j.jneumeth.2011.08.020] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2011] [Revised: 08/10/2011] [Accepted: 08/11/2011] [Indexed: 12/22/2022]
Abstract
The medial prefrontal cortex (mPFC) is an area of the brain critical for higher cognitive processes and implicated in disorders of the CNS such as drug addiction, depression and schizophrenia. Glutamate and acetylcholine are neurotransmitters that are essential for cortical functioning, yet little is known about the dynamic function of these neurotransmitters in subregions of the mPFC. In these studies we used a novel microelectrode array technology to measure resting levels (tonic release) of glutamate and acetylcholine as well as KCl-evoked release (stimulated phasic release) in the mPFC of the anesthetized rat to further our understanding of both tonic and phasic neurotransmission in the cingulate cortex, prelimbic cortex, and infralimbic cortex of the mPFC. Studies revealed homogeneity of tonic and phasic signaling among brain subregions for each neurotransmitter. However, resting levels of glutamate were significantly higher as compared to acetylcholine levels in all subregions. Additionally, KCl-evoked acetylcholine release in the cingulate cortex (7.1 μM) was significantly greater than KCl-evoked glutamate release in any of the three subregions (Cg1, 2.9 μM; PrL, 2.0 μM; IL, 1.8 μM). Interestingly, the time for signal decay following KCl-evoked acetylcholine release was significantly longer by an average of 240% as compared to KCL-evoked glutamate release for all three brain subregions. Finally, we observed a negative relationship between acetylcholine resting levels and KCl-evoked release in the Cg1. These data suggest a homogenous distribution of both glutamatergic and acetylcholinergic innervation in the mPFC, with alterations in tonic and phasic release regulation accounting for differences between these neurotransmitters.
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Demeter E, Hernandez-Garcia L, Sarter M, Lustig C. Challenges to attention: a continuous arterial spin labeling (ASL) study of the effects of distraction on sustained attention. Neuroimage 2011; 54:1518-29. [PMID: 20851189 PMCID: PMC2997179 DOI: 10.1016/j.neuroimage.2010.09.026] [Citation(s) in RCA: 90] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2010] [Revised: 09/07/2010] [Accepted: 09/10/2010] [Indexed: 11/16/2022] Open
Abstract
Maintaining attention and performance over time is an essential part of many activities, and effortful cognitive control is required to avoid vigilance decrements and interference from distraction. Regions at or near right middle frontal gyrus (Brodmann's area (BA) 9), as well as in other prefrontal and parietal areas, are often activated in studies of sustained attention (e.g., Cabeza and Nyberg, 2000; Kim et al., 2006; Lim et al., 2010). This activation has often been interpreted as representing the engagement of cognitive control processes. However, such studies are typically implemented at one level of task difficulty, without an experimental manipulation of control demands. The present study used the distractor condition sustained attention task (dSAT), which has been used extensively in animals to determine the role of neuromodulator systems in attentional performance, to test the hypotheses that BA 9 is sensitive to changes in the demand for cognitive control and that this sensitivity reflects an increased engagement of attentional effort. Continuous arterial spin labeling (ASL) was used to measure neural activity in sixteen healthy, young adults performing a sustained attention task under standard conditions and under a distraction condition that provided an experimental manipulation of demands on cognitive control. The distractor impaired behavioral performance and increased activation in right middle frontal gyrus. Larger increases in right middle frontal gyrus activity were associated with greater behavioral vulnerability to the distractor. These findings indicate that while right middle frontal gyrus regions are sensitive to demands for attentional effort and control, they may not be sufficient to maintain performance under challenge. In addition, they demonstrate the sensitivity of ASL methods to variations in task demands, and suggest that the dSAT may be a useful tool for translational cross-species and clinical research.
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Affiliation(s)
- Elise Demeter
- Neuroscience Program, 530 Church Street, University of Michigan, Ann Arbor, MI 48109-1109, USA
| | - Luis Hernandez-Garcia
- Biomedical Engineering, 2200 Bonisteel Blvd., University of Michigan, Ann Arbor, MI 48109-2099, USA
- FMRI Laboratory, 2360 Bonisteel Blvd, University of Michigan, Ann Arbor, MI 48109-2108, USA
| | - Martin Sarter
- Neuroscience Program, 530 Church Street, University of Michigan, Ann Arbor, MI 48109-1109, USA
- Department of Psychology, 530 Church Street, University of Michigan, Ann Arbor, MI 48109-1109, USA
| | - Cindy Lustig
- Neuroscience Program, 530 Church Street, University of Michigan, Ann Arbor, MI 48109-1109, USA
- Department of Psychology, 530 Church Street, University of Michigan, Ann Arbor, MI 48109-1109, USA
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The dopamine D3 receptor antagonist, S33138, counters cognitive impairment in a range of rodent and primate procedures. Int J Neuropsychopharmacol 2010; 13:1035-51. [PMID: 20663270 DOI: 10.1017/s1461145710000775] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
Although dopamine D(3) receptor antagonists have been shown to enhance frontocortical cholinergic transmission and improve cognitive performance in rodents, data are limited and their effects have never been examined in primates. Accordingly, we characterized the actions of the D(3) receptor antagonist, S33138, in rats and rhesus monkeys using a suite of procedures in which cognitive performance was disrupted by several contrasting manipulations. S33138 dose-dependently (0.01-0.63 mg/kg s.c.) blocked a delay-induced impairment of novel object recognition in rats, a model of visual learning and memory. Further, S33138 (0.16-2.5 mg/kg s.c.) similarly reduced a delay-induced deficit in social novelty discrimination in rats, a procedure principally based on olfactory cues. Adult rhesus monkeys were trained to perform cognitive procedures, then chronically exposed to low doses of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine which produced cognitive impairment without motor disruption. In an attentional set-shifting task of cognitive flexibility involving an extra-dimensional shift, deficits were reversed by S33138 (0.04 and 0.16 mg/kg p.o.). S33138 also significantly improved accuracy (0.04 and 0.16 mg/kg p.o.) at short (but not long) delays in a variable delayed-response task of attention and working memory. Finally, in a separate set of experiments performed in monkeys displaying age-related deficits, S33138 significantly (0.16 and 0.63 mg/kg p.o.) improved task accuracies for long delay intervals in a delayed matching-to-sample task of working memory. In conclusion, S33138 improved performance in several rat and primate procedures of cognitive impairment. These data underpin interest in D(3) receptor blockade as a strategy for improving cognitive performance in CNS disorders like schizophrenia and Parkinson's disease.
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Zhang ZW, Burke MW, Calakos N, Beaulieu JM, Vaucher E. Confocal Analysis of Cholinergic and Dopaminergic Inputs onto Pyramidal Cells in the Prefrontal Cortex of Rodents. Front Neuroanat 2010; 4:21. [PMID: 20589096 PMCID: PMC2893003 DOI: 10.3389/fnana.2010.00021] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2010] [Accepted: 05/05/2010] [Indexed: 11/13/2022] Open
Abstract
Cholinergic and dopaminergic projections to the rat medial prefrontal cortex (mPFC) are both involved in cognitive functions including attention. These neuronal systems modulate mPFC neuronal activity mainly through diffuse transmission. In order to better understand the anatomical level of influence of these systems, confocal microscopy with triple-fluorescent immunolabeling was used in three subregions of the mPFC of rats and Drd1a-tdTomato/Drd2-EGFP transgenic mice. The zone of interaction was defined as a reciprocal microproximity between dopaminergic and cholinergic axonal segments as well as pyramidal neurons. The density of varicosities, along these segments was considered as a possible activity-dependant morphological feature. The percentage of cholinergic and dopaminergic fibers in microproximity ranged from 12 to 40% depending on the layer and mPFC subregion. The cholinergic system appeared to have more influence on dopaminergic fibers since a larger proportion of the dopaminergic fibers were within microproximity to cholinergic fibers. The density of both cholinergic and dopaminergic varicosities was significantly elevated within microproximities. The main results indicate that the cholinergic and dopaminergic systems converge on pyramidal cells in mPFC particularly in the layer V. In transgenic mice 93% of the pyramidal cells expressed the transgenic marker for Drd2 expression, but only 22% expressed the maker for Drd1ar expression. Data presented here suggest that the modulation of mPFC by dopaminergic fibers would be mostly inhibitory and localized at the output level whereas the cholinergic modulation would be exerted at the input and output level both through direct interaction with pyramidal cells and dopaminergic fibers.
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Affiliation(s)
- Zi-Wei Zhang
- School of Optometry, Université de Montréal Montréal, QC, Canada
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Loskutova LV, Kostyunina NV, Dubrovina NI. Involvement of different types of dopamine receptors in the formation of latent inhibition of a conditioned passive avoidance reaction in rats. NEUROSCIENCE AND BEHAVIORAL PHYSIOLOGY 2010; 40:483-7. [PMID: 20490693 DOI: 10.1007/s11055-010-9285-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2008] [Accepted: 10/20/2008] [Indexed: 01/09/2023]
Abstract
The effects of systemic injections of dopaminergic agents on normal and weak latent inhibition of a conditioned passive avoidance reaction were studied in rats. Formation of normal latent inhibition was induced using 20 pre-exposures to a contextual conditioned stimulus prior to training. Weak latent inhibition was modeled using 10 pre-exposures. The effects of the D(2)/D(3) receptor agonist quinpirole (1 mg/kg) and the D(1) receptor agonist SKF 38393 (1 mg/kg) separately and in combination with haloperidol (0.5 mg/kg) were tested. Quinpirole induced the expression of normal latent inhibition but had no effect on weak latent inhibition. Activation of D(1) receptors with SKF 38393 had no effect on the formation of latent inhibition regardless of the number of pre-exposures. Haloperidol significantly strengthened weak latent inhibition but impaired normal latent inhibition. Administration of haloperidol in combination with SKF 38393 prevented this impairment. These results suggest that while D(1) receptors have no influence as an independent substrate on the formation of latent inhibition, activation of these receptors is required for the complete manifestation of D(2)-mediated modulation of this process.
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MESH Headings
- 2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-benzazepine/pharmacology
- Animals
- Avoidance Learning/drug effects
- Avoidance Learning/physiology
- Conditioning, Operant/drug effects
- Conditioning, Operant/physiology
- Dopamine D2 Receptor Antagonists
- Haloperidol/pharmacology
- Male
- Quinpirole/pharmacology
- Rats
- Rats, Wistar
- Receptors, Dopamine D1/agonists
- Receptors, Dopamine D1/antagonists & inhibitors
- Receptors, Dopamine D1/physiology
- Receptors, Dopamine D2/agonists
- Receptors, Dopamine D2/physiology
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Affiliation(s)
- L V Loskutova
- State Research Institute of Physiology, Siberian Branch, Russian Academy of Medical Sciences, Novosibirsk, Russia.
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Alexander KS, Brooks JM, Sarter M, Bruno JP. Disruption of mesolimbic regulation of prefrontal cholinergic transmission in an animal model of schizophrenia and normalization by chronic clozapine treatment. Neuropsychopharmacology 2009; 34:2710-20. [PMID: 19693002 PMCID: PMC2783192 DOI: 10.1038/npp.2009.105] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Abnormal mesolimbic control of cortical cholinergic activity has been hypothesized to contribute to the cognitive symptoms of schizophrenia. Stimulation of NMDA receptors in nucleus accumbens (NAC) increases acetylcholine (ACh) release in prefrontal cortex (PFC), an activation thought to contribute to attentional processing. Thus, the effects of intra-NAC perfusion of NMDA (250-400 microM) on ACh release in PFC were determined in rats receiving lesions of the ventral hippocampus (VH) as neonates (nVHLX), a neurodevelopmental model of schizophrenia, or as adults (aVHLX). NMDA elevated ACh release (100-150% above baseline) in adults sham-lesioned as neonates or in aVHLX rats. Adult nVHLX were unresponsive to NAC NMDA receptor stimulation. The inability of nVHLX to respond to NMDA emerged over development as a separate experiment demonstrated that evoked ACh release was normal before puberty (100-150% increase) yet, in these same nVHLX animals, absent after puberty. Amphetamine-evoked ACh release was assessed in nVHLX animals to exclude potential limitations in release capacity. Amphetamine produced greater increases in ACh release than in shams, indicating that nVHLX does not impair the capacity of cholinergic neurons to release ACh. Finally, the ability of 13 days of pretreatment with clozapine (1.25 mg/kg/day) to reinstate NMDA-evoked cortical ACh efflux was determined. Clozapine treatment normalized NMDA-evoked ACh release in nVHLX animals. These experiments show that mesolimbic regulation of cortical ACh release is disrupted in postpubertal nVHLX rats and normalized by low-dose treatment of clozapine; supporting the usefulness of nVHLX animals for research on the neuronal mechanisms underlying the cognitive symptoms of schizophrenia.
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Affiliation(s)
| | - Julie M. Brooks
- Department of Psychology, The Ohio State University, Columbus, OH
| | - Martin Sarter
- Department of Psychology, University of Michigan, Ann Arbor, MI
| | - John P. Bruno
- Department of Psychology, The Ohio State University, Columbus, OH
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Attentional Focus Modulated by Mesothalamic Dopamine: Consequences in Parkinson’s Disease and Attention Deficit Hyperactivity Disorder. Cognit Comput 2009. [DOI: 10.1007/s12559-009-9029-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Ward RD, Kellendonk C, Simpson EH, Lipatova O, Drew MR, Fairhurst S, Kandel ER, Balsam PD. Impaired timing precision produced by striatal D2 receptor overexpression is mediated by cognitive and motivational deficits. Behav Neurosci 2009; 123:720-30. [PMID: 19634929 DOI: 10.1037/a0016503] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Increased striatal dopamine D2 receptor activity is thought to contribute to the pathophysiology of schizophrenia. To model this condition in mice, Kellendonk et al. (2006) generated transgenic mice that selectively overexpress the D2 receptor in striatum (D2OE). Drew et al. (2007) reported that D2OE mice display deficits in interval timing and motivation. The present study further explored the impaired timing in D2OE mice. Experiment 1 assessed the role of motivation in producing timing deficits in the peak procedure and found that performance in D2OE mice was improved by increasing motivation. In addition, performance was impaired in control mice when motivation was decreased. In Experiment 2, we found that D2OE mice have no timing impairment when tested using the bisection task, a procedure in which the measure of timing performance is less influenced by motivation to respond. In Experiment 3, we also used the bisection task and found selective impairment in timing of long durations in D2OE mice. These results suggest that striatal D2 overexpression impairs timing by decreasing motivation and through its impact on working memory and/or sustained attention.
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Affiliation(s)
- Ryan D Ward
- Department of Psychiatry, Columbia University, NY State Psychiatric Institute, 1051 Riverside Drive, New York, NY 10032, USA
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Martorana A, Mori F, Esposito Z, Kusayanagi H, Monteleone F, Codecà C, Sancesario G, Bernardi G, Koch G. Dopamine modulates cholinergic cortical excitability in Alzheimer's disease patients. Neuropsychopharmacology 2009; 34:2323-8. [PMID: 19516251 DOI: 10.1038/npp.2009.60] [Citation(s) in RCA: 105] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
In Alzheimer's disease (AD) patients dysfunction of cholinergic neurons is considered a typical hallmark, leading to a rationale for the pharmacological treatment in use based on drugs that enhance acetylcholine neurotransmission. However, besides altered acetylcholine transmission, other neurotransmitter systems are involved in cognitive dysfunction leading to dementia. Among others, dopamine seems to be particularly involved in the regulation of cognitive processes, also having functional relationship with acetylcholine. To test whether cholinergic dysfunction can be modified by dopamine, we used short latency afferent inhibition (SLAI) as a neurophysiological tool. First, we tested the function of the cholinergic system in AD patients and in healthy subjects. Then, we tested whether a single L-dopa challenge was able to interfere with this system in both groups. We observed that SLAI was reduced in AD patients, and preserved in normal subjects. L-dopa administration was able to restore SLAI modification only in AD, having no effect in healthy subjects. We conclude that dopamine can modify SLAI in AD, thus confirming the relationship between acetylcholine and dopamine systems. Moreover, it is suggested that together with cholinergic, dopaminergic system alteration is likely to occur in AD, also. These alterations might be responsible, at least in part, for the progressive cognitive decline observed in AD patients.
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Affiliation(s)
- Alessandro Martorana
- Clinica Neurologica, Dipartimento di Neuroscienze, Università di Roma Tor Vergata, Roma, Italy.
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Mørk A, Witten LM, Arnt J. Effect of sertindole on extracellular dopamine, acetylcholine, and glutamate in the medial prefrontal cortex of conscious rats: a comparison with risperidone and exploration of mechanisms involved. Psychopharmacology (Berl) 2009; 206:39-49. [PMID: 19506838 DOI: 10.1007/s00213-009-1578-4] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/28/2008] [Accepted: 05/21/2009] [Indexed: 10/20/2022]
Abstract
RATIONALE Second-generation antipsychotics have some beneficial effect on cognition. Recent studies, furthermore, indicate differential effects of second-generation antipsychotics on impairment in executive cognitive function. OBJECTIVE We evaluated the effect of the second-generation antipsychotic drug, sertindole, on extracellular levels of dopamine (DA), acetylcholine (ACh), and glutamate (Glu) in the rat medial prefrontal cortex (mPFC). Risperidone was studied for comparison. Moreover, selective serotonin 5-HT(2A), 5-HT(2C), and 5-HT(6) receptor antagonists were used, given alone and in combination with the preferential DA D(2) receptor antagonist, haloperidol, to further clarify the action of the two drugs. MATERIALS AND METHODS Rats were treated acutely with vehicle or drugs, and extracellular levels of neurotransmitters were assessed by microdialysis in freely moving animals. RESULTS Sertindole and risperidone significantly increased extracellular levels of DA. Haloperidol; the 5-HT(2A) receptor antagonist, M100907; the 5-HT(2C) receptor antagonist, SB242084; and the 5-HT(6) receptor antagonist, GSK-742457, induced minor increases in levels of DA, but the three latter compounds raised the DA levels notably in combination with haloperidol. Sertindole and risperidone significantly increased the extracellular levels of ACh but only sertindole raised the extracellular levels of Glu. The selective 5-HT(6) receptor antagonist, SB-271046, significantly increased the extracellular levels of Glu. CONCLUSION Sertindole and risperidone markedly increased extracellular levels of DA in mPFC. The built-in 5-HT(2A)/5-HT(2C)/D(2) receptor antagonism of the two drugs might be involved in this action. Both drugs increased the extracellular levels of ACh but only sertindole enhanced Glu levels. The high affinity of sertindole for the 5-HT(6) receptor compared to risperidone may differentiate sertindole from risperidone.
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Affiliation(s)
- Arne Mørk
- Department of Neurophysiology, Discovery Pharmacology Research, H. Lundbeck A/S, Ottiliavej 9, 2500, Valby, Copenhagen, Denmark.
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Grauer SM, Pulito VL, Navarra RL, Kelly MP, Kelley C, Graf R, Langen B, Logue S, Brennan J, Jiang L, Charych E, Egerland U, Liu F, Marquis KL, Malamas M, Hage T, Comery TA, Brandon NJ. Phosphodiesterase 10A Inhibitor Activity in Preclinical Models of the Positive, Cognitive, and Negative Symptoms of Schizophrenia. J Pharmacol Exp Ther 2009; 331:574-90. [DOI: 10.1124/jpet.109.155994] [Citation(s) in RCA: 225] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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Zmarowski A, Wu HQ, Brooks JM, Potter MC, Pellicciari R, Schwarcz R, Bruno JP. Astrocyte-derived kynurenic acid modulates basal and evoked cortical acetylcholine release. Eur J Neurosci 2009; 29:529-38. [PMID: 19187269 DOI: 10.1111/j.1460-9568.2008.06594.x] [Citation(s) in RCA: 93] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
We tested the hypothesis that fluctuations in the levels of kynurenic acid (KYNA), an endogenous antagonist of the alpha7 nicotinic acetylcholine (ACh) receptor, modulate extracellular ACh levels in the medial prefrontal cortex in rats. Decreases in cortical KYNA levels were achieved by local perfusion of S-ESBA, a selective inhibitor of the astrocytic enzyme kynurenine aminotransferase II (KAT II), which catalyses the formation of KYNA from its precursor L-kynurenine. At 5 mm, S-ESBA caused a 30% reduction in extracellular KYNA levels, which was accompanied by a two-threefold increase in basal cortical ACh levels. Co-perfusion of KYNA in the endogenous range (100 nm), which by itself tended to reduce basal ACh levels, blocked the ability of S-ESBA to raise extracellular ACh levels. KYNA perfusion (100 nm) also prevented the evoked ACh release caused by d-amphetamine (2.0 mg/kg). This effect was duplicated by the systemic administration of kynurenine (50 mg/kg), which resulted in a significant increase in cortical KYNA formation. Jointly, these data indicate that astrocytes, by producing and releasing KYNA, have the ability to modulate cortical cholinergic neurotransmission under both basal and stimulated conditions. As cortical KYNA levels are elevated in individuals with schizophrenia, and in light of the established role of cortical ACh in executive functions, our findings suggest that drugs capable of attenuating the production of KYNA may be of benefit in the treatment of cognitive deficits in schizophrenia.
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Affiliation(s)
- A Zmarowski
- Department of Psychology and Neuroscience, The Ohio State University, Columbus, OH 43210, USA
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Pezze MA, Dalley JW, Robbins TW. Remediation of attentional dysfunction in rats with lesions of the medial prefrontal cortex by intra-accumbens administration of the dopamine D(2/3) receptor antagonist sulpiride. Psychopharmacology (Berl) 2009; 202:307-13. [PMID: 18985321 DOI: 10.1007/s00213-008-1384-4] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/11/2008] [Accepted: 10/16/2008] [Indexed: 12/30/2022]
Abstract
RATIONALE Anti-psychotic drugs are widely recognised to produce beneficial effects on impaired cognition in schizophrenia but their mechanism of action is poorly understood. The prefrontal cortex (PFC) and nucleus accumbens (NAC) are key brain loci considered to mediate many of the cognitive deficits associated with schizophrenia and related disorders. OBJECTIVES To investigate (1) the effects of selective damage to the PFC on visuo-spatial attention and cognition in the rat and (2) the ability of the anti-psychotic drug sulpiride after its intra-NAC administration to ameliorate cognitive and behavioural deficits produced by lesions of the PFC. METHODS Selective lesions of the medial PFC were made using quinolinic acid in rats previously trained on a five-choice serial reaction time task of sustained visual attention (n = 7). Sham rats received phosphate-buffered saline infusions (n = 7). Following a period of recovery, low doses of sulpiride (0.5 ng or 1 ng) were infused into the core sub-region of the NAC of sham and lesioned rats immediately prior to testing on the five-choice task. RESULTS Lesions of the medial PFC produced a range of impairments on the five-choice task, including decreased attentional accuracy, slower latencies to respond correctly and increased omissions and premature responses, the latter an operational measure of impulsivity. Intra-NAC sulpiride dose-dependently ameliorated the increased impulsivity and attentional impairment present in PFC-lesioned rats. CONCLUSIONS These findings suggest that attentional and cognitive impairment in schizophrenia may be determined in part by a dysregulation of the subcortical dopamine systems occurring as a consequence of damage to the PFC.
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Affiliation(s)
- Marie A Pezze
- Department of Experimental Psychology, University of Cambridge, Downing St, Cambridge CB23EB, UK
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Critical Evaluation of Acetylcholine Determination in Rat Brain Microdialysates using Ion-Pair Liquid Chromatography with Amperometric Detection. SENSORS 2008; 8:5171-5185. [PMID: 27873808 PMCID: PMC3705495 DOI: 10.3390/s8085171] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/01/2008] [Revised: 08/24/2008] [Accepted: 08/25/2008] [Indexed: 01/16/2023]
Abstract
Liquid chromatography with amperometric detection remains the most widely used method for acetylcholine quantification in microdialysis samples. Separation of acetylcholine from choline and other matrix components on a microbore chromatographic column (1 mm internal diameter), conversion of acetylcholine in an immobilized enzyme reactor and detection of the produced hydrogen peroxide on a horseradish peroxidase redox polymer coated glassy carbon electrode, achieves sufficient sensitivity for acetylcholine quantification in rat brain microdialysates. However, a thourough validation within the concentration range required for this application has not been carried out before. Furthermore, a rapid degradation of the chromatographic columns and enzyme systems have been reported. In the present study an ion-pair liquid chromatography assay with amperometric detection was validated and its long-term stability evaluated. Working at pH 6.5 dramatically increased chromatographic stability without a loss in sensitivity compared to higher pH values. The lower limit of quantification of the method was 0.3 nM. At this concentration the repeatability was 15.7%, the inter-day precision 8.7% and the accuracy 103.6%. The chromatographic column was stable over 4 months, the immobilized enzyme reactor up to 2-3 months and the enzyme coating of the amperometric detector up to 1-2 months. The concentration of acetylcholine in 30 μl microdialysates obtained under basal conditions from the hippocampus of freely moving rats was 0.40 ± 0.12 nM (mean ± SD, n = 30). The present method is therefore suitable for acetylcholine determination in rat brain microdialysates.
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