1
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Liao W, Lee KZ. CDKL5-mediated developmental tuning of neuronal excitability and concomitant regulation of transcriptome. Hum Mol Genet 2023; 32:3276-3298. [PMID: 37688574 DOI: 10.1093/hmg/ddad149] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2023] [Revised: 08/31/2023] [Accepted: 09/06/2023] [Indexed: 09/11/2023] Open
Abstract
Cyclin-dependent kinase-like 5 (CDKL5) is a serine-threonine kinase enriched in the forebrain to regulate neuronal development and function. Patients with CDKL5 deficiency disorder (CDD), a severe neurodevelopmental condition caused by mutations of CDKL5 gene, present early-onset epilepsy as the most prominent feature. However, spontaneous seizures have not been reported in mouse models of CDD, raising vital questions on the human-mouse differences and the roles of CDKL5 in early postnatal brains. Here, we firstly measured electroencephalographic (EEG) activities via a wireless telemetry system coupled with video-recording in neonatal mice. We found that mice lacking CDKL5 exhibited spontaneous epileptic EEG discharges, accompanied with increased burst activities and ictal behaviors, specifically at postnatal day 12 (P12). Intriguingly, those epileptic spikes disappeared after P14. We next performed an unbiased transcriptome profiling in the dorsal hippocampus and motor cortex of Cdkl5 null mice at different developmental timepoints, uncovering a set of age-dependent and brain region-specific alterations of gene expression in parallel with the transient display of epileptic activities. Finally, we validated multiple differentially expressed genes, such as glycine receptor alpha 2 and cholecystokinin, at the transcript or protein levels, supporting the relevance of these genes to CDKL5-regulated excitability. Our findings reveal early-onset neuronal hyperexcitability in mouse model of CDD, providing new insights into CDD etiology and potential molecular targets to ameliorate intractable neonatal epilepsy.
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Affiliation(s)
- Wenlin Liao
- Institute of Neuroscience, National Cheng-Chi University, Taipei 116, Taiwan
- Research Center for Mind, Brain and Learning, National Cheng-Chi University, Taipei 116, Taiwan
| | - Kun-Ze Lee
- Department of Biological Sciences, National Sun Yat-Sen University, No. 70, Lienhai Road, Kaohsiung 80424, Taiwan
- Department of Biomedical Science and Environmental Biology, Kaohsiung Medical University, 100, Shih-Chuan 1st Road, Kaohsiung 80708, Taiwan
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2
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Di Domenico D, Mapelli L. Dopaminergic Modulation of Prefrontal Cortex Inhibition. Biomedicines 2023; 11:biomedicines11051276. [PMID: 37238947 DOI: 10.3390/biomedicines11051276] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2023] [Revised: 04/21/2023] [Accepted: 04/23/2023] [Indexed: 05/28/2023] Open
Abstract
The prefrontal cortex is the highest stage of integration in the mammalian brain. Its functions vary greatly, from working memory to decision-making, and are primarily related to higher cognitive functions. This explains the considerable effort devoted to investigating this area, revealing the complex molecular, cellular, and network organization, and the essential role of various regulatory controls. In particular, the dopaminergic modulation and the impact of local interneurons activity are critical for prefrontal cortex functioning, controlling the excitatory/inhibitory balance and the overall network processing. Though often studied separately, the dopaminergic and GABAergic systems are deeply intertwined in influencing prefrontal network processing. This mini review will focus on the dopaminergic modulation of GABAergic inhibition, which plays a significant role in shaping prefrontal cortex activity.
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Affiliation(s)
- Danila Di Domenico
- Department of Brain and Behavioral Sciences, University of Pavia, 27100 Pavia, Italy
| | - Lisa Mapelli
- Department of Brain and Behavioral Sciences, University of Pavia, 27100 Pavia, Italy
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3
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Armenta-Resendiz M, Assali A, Tsvetkov E, Cowan CW, Lavin A. Repeated methamphetamine administration produces cognitive deficits through augmentation of GABAergic synaptic transmission in the prefrontal cortex. Neuropsychopharmacology 2022; 47:1816-1825. [PMID: 35788684 PMCID: PMC9372065 DOI: 10.1038/s41386-022-01371-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/02/2022] [Revised: 06/14/2022] [Accepted: 06/22/2022] [Indexed: 11/08/2022]
Abstract
Methamphetamine (METH) abuse is associated with the emergence of cognitive deficits and hypofrontality, a pathophysiological marker of many neuropsychiatric disorders that is produced by altered balance of local excitatory and inhibitory synaptic transmission. However, there is a dearth of information regarding the cellular and synaptic mechanisms underlying METH-induced cognitive deficits and associated hypofrontal states. Using PV-Cre transgenic rats that went through a METH sensitization regime or saline (SAL) followed by 7-10 days of home cage abstinence combined with cognitive tests, chemogenetic experiments, and whole-cell patch recordings on the prelimbic prefrontal cortex (PFC), we investigated the cellular and synaptic mechanisms underlying METH-induce hypofrontality. We report here that repeated METH administration in rats produces deficits in working memory and increases in inhibitory synaptic transmission onto pyramidal neurons in the PFC. The increased PFC inhibition is detected by an increase in spontaneous and evoked inhibitory postsynaptic synaptic currents (IPSCs), an increase in GABAergic presynaptic function, and a shift in the excitatory-inhibitory balance onto PFC deep-layer pyramidal neurons. We find that pharmacological blockade of D1 dopamine receptor function reduces the METH-induced augmentation of IPSCs, suggesting a critical role for D1 dopamine signaling in METH-induced hypofrontality. In addition, repeated METH administration increases the intrinsic excitability of parvalbumin-positive fast spiking interneurons (PV + FSIs), a key local interneuron population in PFC that contributes to the control of inhibitory tone. Using a cell type-specific chemogenetic approach, we show that increasing PV + FSIs activity in the PFC is necessary and sufficient to cause deficits in temporal order memory similar to those induced by METH. Conversely, reducing PV + FSIs activity in the PFC of METH-exposed rats rescues METH-induced temporal order memory deficits. Together, our findings reveal that repeated METH exposure increases PFC inhibitory tone through a D1 dopamine signaling-dependent potentiation of inhibitory synaptic transmission, and that reduction of PV + FSIs activity can rescue METH-induced cognitive deficits, suggesting a potential therapeutic approach to treating cognitive symptoms in patients suffering from METH use disorder.
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Affiliation(s)
| | - Ahlem Assali
- Department of Neuroscience, Medical University of South Carolina, Charleston, SC, USA
| | - Evgeny Tsvetkov
- Department of Neuroscience, Medical University of South Carolina, Charleston, SC, USA
| | - Christopher W Cowan
- Department of Neuroscience, Medical University of South Carolina, Charleston, SC, USA
| | - Antonieta Lavin
- Department of Neuroscience, Medical University of South Carolina, Charleston, SC, USA.
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4
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Fuchsberger T, Paulsen O. Modulation of hippocampal plasticity in learning and memory. Curr Opin Neurobiol 2022; 75:102558. [PMID: 35660989 DOI: 10.1016/j.conb.2022.102558] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Revised: 04/15/2022] [Accepted: 04/25/2022] [Indexed: 11/17/2022]
Abstract
Synaptic plasticity plays a central role in the study of neural mechanisms of learning and memory. Plasticity rules are not invariant over time but are under neuromodulatory control, enabling behavioral states to influence memory formation. Neuromodulation controls synaptic plasticity at network level by directing information flow, at circuit level through changes in excitation/inhibition balance, and at synaptic level through modulation of intracellular signaling cascades. Although most research has focused on modulation of principal neurons, recent progress has uncovered important roles for interneurons in not only routing information, but also setting conditions for synaptic plasticity. Moreover, astrocytes have been shown to both gate and mediate plasticity. These additional mechanisms must be considered for a comprehensive mechanistic understanding of learning and memory.
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Affiliation(s)
- Tanja Fuchsberger
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, UK
| | - Ole Paulsen
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, UK.
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5
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Anastasiades PG, Boada C, Carter AG. Cell-Type-Specific D1 Dopamine Receptor Modulation of Projection Neurons and Interneurons in the Prefrontal Cortex. Cereb Cortex 2020; 29:3224-3242. [PMID: 30566584 DOI: 10.1093/cercor/bhy299] [Citation(s) in RCA: 53] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2018] [Revised: 11/01/2018] [Accepted: 11/07/2018] [Indexed: 11/14/2022] Open
Abstract
Dopamine modulation in the prefrontal cortex (PFC) mediates diverse effects on neuronal physiology and function, but the expression of dopamine receptors at subpopulations of projection neurons and interneurons remains unresolved. Here, we examine D1 receptor expression and modulation at specific cell types and layers in the mouse prelimbic PFC. We first show that D1 receptors are enriched in pyramidal cells in both layers 5 and 6, and that these cells project to intratelencephalic targets including contralateral cortex, striatum, and claustrum rather than to extratelencephalic structures. We then find that D1 receptors are also present in interneurons and enriched in superficial layer VIP-positive (VIP+) interneurons that coexpresses calretinin but absent from parvalbumin-positive (PV+) and somatostatin-positive (SOM+) interneurons. Finally, we determine that D1 receptors strongly and selectively enhance action potential firing in only a subset of these corticocortical neurons and VIP+ interneurons. Our findings define several novel subpopulations of D1+ neurons, highlighting how modulation via D1 receptors can influence both excitatory and disinhibitory microcircuits in the PFC.
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Affiliation(s)
- Paul G Anastasiades
- Center for Neural Science, New York University, 4 Washington Place, New York, NY, USA
| | - Christina Boada
- Center for Neural Science, New York University, 4 Washington Place, New York, NY, USA
| | - Adam G Carter
- Center for Neural Science, New York University, 4 Washington Place, New York, NY, USA
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6
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Zhong P, Qin L, Yan Z. Dopamine Differentially Regulates Response Dynamics of Prefrontal Cortical Principal Neurons and Interneurons to Optogenetic Stimulation of Inputs from Ventral Tegmental Area. Cereb Cortex 2020; 30:4402-4409. [PMID: 32236403 PMCID: PMC7325712 DOI: 10.1093/cercor/bhaa027] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2019] [Revised: 12/06/2019] [Accepted: 01/11/2020] [Indexed: 01/15/2023] Open
Abstract
Prefrontal cortex (PFC) is highly influenced by the inputs from ventral tegmental area (VTA); however, how the projection from VTA impacts PFC neurons and how the synaptically released dopamine affects PFC activity are largely unclear. Using optogenetics and electrophysiological approaches, we examined the impact of VTA stimulation on PFC principal neurons and parvalbumin-positive (PV+) interneurons and the modulatory role of dopamine. We found that the brief activation of the VTA-PFC circuit immediately induced action potential firing, which was mediated by glutamatergic transmission. However, strong stimulation of VTA gradually induced a marked and prolonged enhancement of the excitability of PFC PV+ interneurons and a modest and short-lived enhancement of the excitability of PFC principal neurons. Blocking dopamine receptors (DARs) shortened the VTA excitation of PFC PV+ interneurons and prolonged the VTA excitation of PFC principal neurons. Blocking GABAA receptors induced a similar effect as DAR antagonists in PFC principal neurons, suggesting that the dopaminergic effect is through influencing the inhibitory transmission system. These results have revealed a role of dopamine in regulating the temporal dynamics of excitation/inhibition balance in VTA-PFC circuit, which provides insights into the functional consequence of activating dopamine system in the mesocortical system.
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Affiliation(s)
- Ping Zhong
- Department of Physiology and Biophysics, Jacobs School of Medicine and Biomedical Sciences, State University of New York at Buffalo, Buffalo 14203, NY, USA
| | - Luye Qin
- Department of Physiology and Biophysics, Jacobs School of Medicine and Biomedical Sciences, State University of New York at Buffalo, Buffalo 14203, NY, USA
| | - Zhen Yan
- Department of Physiology and Biophysics, Jacobs School of Medicine and Biomedical Sciences, State University of New York at Buffalo, Buffalo 14203, NY, USA
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7
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Ranjbar-Slamloo Y, Fazlali Z. Dopamine and Noradrenaline in the Brain; Overlapping or Dissociate Functions? Front Mol Neurosci 2020; 12:334. [PMID: 32038164 PMCID: PMC6986277 DOI: 10.3389/fnmol.2019.00334] [Citation(s) in RCA: 98] [Impact Index Per Article: 24.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2019] [Accepted: 12/27/2019] [Indexed: 12/21/2022] Open
Abstract
Dopamine and noradrenaline are crucial neuromodulators controlling brain states, vigilance, action, reward, learning, and memory processes. Ventral tegmental area (VTA) and Locus Coeruleus (LC) are canonically described as the main sources of dopamine (DA) and noradrenaline (NA) with dissociate functions. A comparison of diverse studies shows that these neuromodulators largely overlap in multiple domains such as shared biosynthetic pathway and co-release from the LC terminals, convergent innervations, non-specificity of receptors and transporters, and shared intracellular signaling pathways. DA–NA interactions are mainly studied in prefrontal cortex and hippocampus, yet it can be extended to the whole brain given the diversity of catecholamine innervations. LC can simultaneously broadcast both dopamine and noradrenaline across the brain. Here, we briefly review the molecular, cellular, and physiological overlaps between DA and NA systems and point to their functional implications. We suggest that DA and NA may function in parallel to facilitate learning and maintain the states required for normal cognitive processes. Various signaling modules of NA and DA have been targeted for developing of therapeutics. Understanding overlaps of the two systems is crucial for more effective interventions in a range of neuropsychiatric conditions.
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Affiliation(s)
- Yadollah Ranjbar-Slamloo
- Eccles Institute of Neuroscience, The John Curtin School of Medical Research, The Australian National University, Canberra, ACT, Australia
| | - Zeinab Fazlali
- Department of Biomedical Engineering, Columbia University, New York, NY, United States
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8
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Madadi Asl M, Vahabie AH, Valizadeh A. Dopaminergic Modulation of Synaptic Plasticity, Its Role in Neuropsychiatric Disorders, and Its Computational Modeling. Basic Clin Neurosci 2019; 10:1-12. [PMID: 31031889 PMCID: PMC6484184 DOI: 10.32598/bcn.9.10.125] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2017] [Revised: 11/25/2017] [Accepted: 02/05/2018] [Indexed: 01/14/2023] Open
Abstract
Neuromodulators modify intrinsic characteristics of the nervous system in order to reconfigure the functional properties of neural circuits. This reconfiguration is crucial for the flexibility of the nervous system to respond on an input-modulated basis. Such a functional rearrangement is realized by modification of intrinsic properties of the neural circuits including synaptic interactions. Dopamine is an important neuromodulator involved in motivation and stimulus-reward learning process, and adjusts synaptic dynamics in multiple time scales through different pathways. The modification of synaptic plasticity by dopamine underlies the change in synaptic transmission and integration mechanisms, which affects intrinsic properties of the neural system including membrane excitability, probability of neurotransmitters release, receptors’ response to neurotransmitters, protein trafficking, and gene transcription. Dopamine also plays a central role in behavioral control, whereas its malfunction can cause cognitive disorders. Impaired dopamine signaling is implicated in several neuropsychiatric disorders such as Parkinson’s disease, drug addiction, schizophrenia, attention-deficit/hyperactivity disorder, obsessive-compulsive disorder and Tourette’s syndrome. Therefore, dopamine plays a crucial role in the nervous system, where its proper modulation of neural circuits may enhance plasticity-related procedures, but disturbances in dopamine signaling might be involved in numerous neuropsychiatric disorders. In recent years, several computational models are proposed to formulate the involvement of dopamine in synaptic plasticity or neuropsychiatric disorders and address their connection based on the experimental findings.
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Affiliation(s)
- Mojtaba Madadi Asl
- Department of Physics, Institute for Advanced Studies in Basic Sciences (IASBS), Zanjan, Iran
| | - Abdol-Hossein Vahabie
- School of Cognitive Sciences, Institute for Research in Fundamental Sciences (IPM), Tehran, Iran
| | - Alireza Valizadeh
- Department of Physics, Institute for Advanced Studies in Basic Sciences (IASBS), Zanjan, Iran.,School of Cognitive Sciences, Institute for Research in Fundamental Sciences (IPM), Tehran, Iran
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9
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Downregulation of Dopamine D1-like Receptor Pathways of GABAergic Interneurons in the Anterior Cingulate Cortex of Spontaneously Hypertensive Rats. Neuroscience 2018; 394:267-285. [DOI: 10.1016/j.neuroscience.2018.10.039] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2018] [Revised: 09/28/2018] [Accepted: 10/22/2018] [Indexed: 01/09/2023]
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10
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Wakeford AG, Morin EL, Bramlett SN, Howell LL, Sanchez MM. A review of nonhuman primate models of early life stress and adolescent drug abuse. Neurobiol Stress 2018; 9:188-198. [PMID: 30450384 PMCID: PMC6236515 DOI: 10.1016/j.ynstr.2018.09.005] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2018] [Revised: 07/30/2018] [Accepted: 09/12/2018] [Indexed: 01/03/2023] Open
Abstract
Adolescence represents a developmental stage in which initiation of drug use typically occurs and is marked by dynamic neurobiological changes. These changes present a sensitive window during which perturbations to normative development lead to alterations in brain circuits critical for stress and emotional regulation as well as reward processing, potentially resulting in an increased susceptibility to psychopathologies. The occurrence of early life stress (ELS) is related to a greater risk for the development of substance use disorders (SUD) during adolescence. Studies using nonhuman primates (NHP) are ideally suited to examine how ELS may alter the development of neurobiological systems modulating the reinforcing effects of drugs, given their remarkable neurobiological, behavioral, and developmental homologies to humans. This review examines NHP models of ELS that have been used to characterize its effects on sensitivity to drug reinforcement, and proposes future directions using NHP models of ELS and drug abuse in an effort to develop more targeted intervention and prevention strategies for at risk clinical populations. ELS has long-lasting neurobiological and behavioral consequences. ELS is a major risk factor for the initiation of adolescent drug use. Sex differences are apparent in the consequences of ELS, including drug use. Nonhuman primate models of ELS are critical for understanding ELS effects on neurobiology and risk for adolescent drug use.
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Affiliation(s)
- Alison G.P. Wakeford
- Division of Developmental and Cognitive Neuroscience, Yerkes National Primate Research Center, Emory University, 954 Gatewood Rd NE, Atlanta, GA, 30329, United States
- Department of Psychiatry & Behavioral Sciences, Emory University, 12 Executive Park Dr NE #200, Atlanta, GA, 30329, United States
- Corresponding author. Yerkes National Primate Research Center, Emory University, 954 Gatewood Rd NE, Atlanta, GA, 30329, United States.
| | - Elyse L. Morin
- Division of Developmental and Cognitive Neuroscience, Yerkes National Primate Research Center, Emory University, 954 Gatewood Rd NE, Atlanta, GA, 30329, United States
- Department of Psychiatry & Behavioral Sciences, Emory University, 12 Executive Park Dr NE #200, Atlanta, GA, 30329, United States
| | - Sara N. Bramlett
- Division of Developmental and Cognitive Neuroscience, Yerkes National Primate Research Center, Emory University, 954 Gatewood Rd NE, Atlanta, GA, 30329, United States
- Department of Psychiatry & Behavioral Sciences, Emory University, 12 Executive Park Dr NE #200, Atlanta, GA, 30329, United States
| | - Leonard L. Howell
- Division of Neuropharmacology and Neurologic Diseases, Yerkes National Primate Research Center, Emory University, 954 Gatewood Rd NE, Atlanta, GA, 30329, United States
- Department of Psychiatry & Behavioral Sciences, Emory University, 12 Executive Park Dr NE #200, Atlanta, GA, 30329, United States
| | - Mar M. Sanchez
- Division of Developmental and Cognitive Neuroscience, Yerkes National Primate Research Center, Emory University, 954 Gatewood Rd NE, Atlanta, GA, 30329, United States
- Department of Psychiatry & Behavioral Sciences, Emory University, 12 Executive Park Dr NE #200, Atlanta, GA, 30329, United States
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11
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Noda Y, Barr MS, Zomorrodi R, Cash RFH, Farzan F, Rajji TK, Chen R, Daskalakis ZJ, Blumberger DM. Evaluation of short interval cortical inhibition and intracortical facilitation from the dorsolateral prefrontal cortex in patients with schizophrenia. Sci Rep 2017; 7:17106. [PMID: 29213090 PMCID: PMC5719013 DOI: 10.1038/s41598-017-17052-3] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2017] [Accepted: 11/21/2017] [Indexed: 02/05/2023] Open
Abstract
GABAergic and glutamatergic dysfunction in the dorsolateral prefrontal cortex (DLPFC) are thought to be the core pathophysiological mechanisms of schizophrenia. Recently, we have established a method to index these functions from the DLPFC using the paired transcranial magnetic stimulation (TMS) paradigms of short interval intracortical inhibition (SICI) and facilitation (ICF) combined with electroencephalography (EEG). In this study, we aimed to evaluate neurophysiological indicators related to GABAA and glutamate receptor-mediated functions respectively from the DLPFC in patients with schizophrenia using these paradigms, compared to healthy controls. Given that these activities contribute to cognitive functions, the relationship between the TMS-evoked potential (TEP) modulations by SICI/ICF and cognitive/clinical measures were explored. Compared to controls, patients showed reduced inhibition in P60 (t22 = −4.961, p < 0.0001) by SICI and reduced facilitation in P60 (t22 = 5.174, p < 0.0001) and N100 (t22 = 3.273, p = 0.003) by ICF. In patients, the modulation of P60 by SICI was correlated with the longest span of the Letter-Number Span Test (r = −0.775, p = 0.003), while the modulation of N100 by ICF was correlated with the total score of the Positive and Negative. Syndrome Scale (r = 0.817, p = 0.002). These findings may represent the pathophysiology, which may be associated with prefrontal GABAA and glutamatergic dysfunctions, in the expression of symptoms of schizophrenia.
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Affiliation(s)
- Yoshihiro Noda
- Temerty Centre for Therapeutic Brain Intervention, Centre for Addiction and Mental Health, Toronto, Ontario, M6J 1H4, Canada.,Department of Psychiatry, University of Toronto, Toronto, Ontario, M5T 1R8, Canada
| | - Mera S Barr
- Temerty Centre for Therapeutic Brain Intervention, Centre for Addiction and Mental Health, Toronto, Ontario, M6J 1H4, Canada.,Department of Psychiatry, University of Toronto, Toronto, Ontario, M5T 1R8, Canada.,Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Toronto, Ontario, M5T 1R8, Canada
| | - Reza Zomorrodi
- Temerty Centre for Therapeutic Brain Intervention, Centre for Addiction and Mental Health, Toronto, Ontario, M6J 1H4, Canada
| | - Robin F H Cash
- Division of Neurology, Department of Medicine, University of Toronto, Division of Brain, Imaging and Behaviour - Systems Neuroscience, Krembil Research Institute, University Health Network, Toronto, M5T 2S8, Ontario, Canada
| | - Faranak Farzan
- Temerty Centre for Therapeutic Brain Intervention, Centre for Addiction and Mental Health, Toronto, Ontario, M6J 1H4, Canada.,Department of Psychiatry, University of Toronto, Toronto, Ontario, M5T 1R8, Canada.,Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Toronto, Ontario, M5T 1R8, Canada
| | - Tarek K Rajji
- Temerty Centre for Therapeutic Brain Intervention, Centre for Addiction and Mental Health, Toronto, Ontario, M6J 1H4, Canada.,Department of Psychiatry, University of Toronto, Toronto, Ontario, M5T 1R8, Canada.,Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Toronto, Ontario, M5T 1R8, Canada
| | - Robert Chen
- Division of Neurology, Department of Medicine, University of Toronto, Division of Brain, Imaging and Behaviour - Systems Neuroscience, Krembil Research Institute, University Health Network, Toronto, M5T 2S8, Ontario, Canada
| | - Zafiris J Daskalakis
- Temerty Centre for Therapeutic Brain Intervention, Centre for Addiction and Mental Health, Toronto, Ontario, M6J 1H4, Canada.,Department of Psychiatry, University of Toronto, Toronto, Ontario, M5T 1R8, Canada.,Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Toronto, Ontario, M5T 1R8, Canada
| | - Daniel M Blumberger
- Temerty Centre for Therapeutic Brain Intervention, Centre for Addiction and Mental Health, Toronto, Ontario, M6J 1H4, Canada. .,Department of Psychiatry, University of Toronto, Toronto, Ontario, M5T 1R8, Canada. .,Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Toronto, Ontario, M5T 1R8, Canada.
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12
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Nimitvilai S, Lopez MF, Mulholland PJ, Woodward JJ. Ethanol Dependence Abolishes Monoamine and GIRK (Kir3) Channel Inhibition of Orbitofrontal Cortex Excitability. Neuropsychopharmacology 2017; 42:1800-1812. [PMID: 28139680 PMCID: PMC5520780 DOI: 10.1038/npp.2017.22] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/10/2016] [Revised: 01/18/2017] [Accepted: 01/21/2017] [Indexed: 01/03/2023]
Abstract
Alcohol abuse disorders are associated with dysfunction of frontal cortical areas including the orbitofrontal cortex (OFC). The OFC is extensively innervated by monoamines, and drugs that target monoamine receptors have been used to treat a number of neuropsychiatric diseases, including alcoholism. However, little is known regarding how monoamines affect OFC neuron excitability or whether this modulation is altered by chronic exposure to ethanol. In this study, we examined the effect of dopamine, norepinephrine, and serotonin on lOFC neuronal excitability in naive mice and in those exposed to chronic intermittent ethanol (CIE) treatment. All three monoamines decreased current-evoked spike firing of lOFC neurons and this action required Giα-coupled D2, α2-adrenergic, and 5HT1A receptors, respectively. Inhibition of firing by dopamine or the D2 agonist quinpirole, but not norepinephrine or serotonin, was prevented by the GABAA receptor antagonist picrotoxin. GABA-mediated tonic current was enhanced by dopamine or the D1 agonist SKF81297 but not quinpirole, whereas the amplitude of spontaneous IPSCs was increased by quinpirole but not dopamine. Spiking was also inhibited by the direct GIRK channel activator ML297, whereas blocking these channels with barium increased firing and eliminated the inhibitory actions of monoamines. In the presence of ML297 or the G-protein blocker GDP-β-S, DA induced a further decrease in spike firing, suggesting the involvement of a non-GIRK channel mechanism. In neurons from CIE-treated mice, spike frequency was nearly doubled and inhibition of firing by monoamines or ML297 was lost. These effects occurred in the absence of significant changes in expression of Gi/o or GIRK channel proteins. Together, these findings show that monoamines are important modulators of lOFC excitability and suggest that disruption of this process could contribute to various deficits associated with alcohol dependence.
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Affiliation(s)
- Sudarat Nimitvilai
- Department of Neuroscience, Medical University of South Carolina, Charleston, SC, USA
| | - Marcelo F Lopez
- Department of Psychiatry and Behavioral Sciences, Medical University of South Carolina, Charleston, SC, USA
| | - Patrick J Mulholland
- Department of Neuroscience, Medical University of South Carolina, Charleston, SC, USA,Department of Psychiatry and Behavioral Sciences, Medical University of South Carolina, Charleston, SC, USA
| | - John J Woodward
- Department of Neuroscience, Medical University of South Carolina, Charleston, SC, USA,Department of Psychiatry and Behavioral Sciences, Medical University of South Carolina, Charleston, SC, USA,Department of Neuroscience, Medical University of South Carolina, 67 President Street, IOP456N, Charleston, SC 29425, USA, Tel: 843 792 5225, Fax: 843 792 7353, E-mail:
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13
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Lupinsky D, Moquin L, Gratton A. Interhemispheric regulation of the rat medial prefrontal cortical glutamate stress response: role of local GABA- and dopamine-sensitive mechanisms. Psychopharmacology (Berl) 2017; 234:353-363. [PMID: 27822602 DOI: 10.1007/s00213-016-4468-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/09/2016] [Accepted: 10/21/2016] [Indexed: 11/26/2022]
Abstract
RATIONALE We previously reported that stressors increase medial prefrontal cortex (PFC) glutamate (GLU) levels as a result of activating callosal neurons located in the opposite hemisphere and that this PFC GLU stress response is regulated by GLU-, dopamine- (DA-), and GABA-sensitive mechanisms (Lupinsky et al. 2010). OBJECTIVES Here, we examine the possibility that PFC DA regulates the stress responsivity of callosal neurons indirectly by acting at D1 and D2 receptors located on GABA interneurons. METHODS Microdialysis combined with drug perfusion (reverse dialysis) or microinjections was used in adult male Long-Evans rats to characterize D1, D2, and GABAB receptor-mediated regulation of the PFC GABA response to tail-pinch (TP) stress. RESULTS We report that TP stress reliably elicited comparable increases in extracellular GABA in the left and right PFCs. SCH23390 (D1 antagonist; 100 μM perfusate concentration) perfused by reverse microdialysis attenuated the local GABA stress responses equally in the left and right PFCs. Intra-PFC raclopride perfusion (D2 antagonist; 100 μM) had the opposite effect, not only potentiating the local GABA stress response but also causing a transient elevation in basal (pre-stress) GABA. Moreover, unilateral PFC raclopride microinjection (6 nmol) attenuated the GLU response to TP stress in the contralateral PFC. Finally, intra-PFC baclofen perfusion (GABAB agonist; 100 μM) inhibited the local GLU and GABA stress responses. CONCLUSIONS Taken together, these findings implicate PFC GABA interneurons in processing stressful stimuli, showing that local D1, D2, and GABAB receptor-mediated changes in PFC GABA transmission play a crucial role in the interhemispheric regulation of GLU stress responsivity.
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Affiliation(s)
- Derek Lupinsky
- Department of Psychiatry, McGill University, Montréal, Québec, H4H 1R3, Canada.
- Douglas Institute Research Center, 6875 LaSalle Blvd, Montréal, Québec, H4H 1R3, Canada.
| | - Luc Moquin
- Douglas Institute Research Center, 6875 LaSalle Blvd, Montréal, Québec, H4H 1R3, Canada
| | - Alain Gratton
- Department of Psychiatry, McGill University, Montréal, Québec, H4H 1R3, Canada
- Douglas Institute Research Center, 6875 LaSalle Blvd, Montréal, Québec, H4H 1R3, Canada
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Monoaminergic control of brain states and sensory processing: Existing knowledge and recent insights obtained with optogenetics. Prog Neurobiol 2016; 151:237-253. [PMID: 27634227 DOI: 10.1016/j.pneurobio.2016.09.003] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2016] [Revised: 08/18/2016] [Accepted: 09/10/2016] [Indexed: 01/18/2023]
Abstract
Monoamines are key neuromodulators involved in a variety of physiological and pathological brain functions. Classical studies using physiological and pharmacological tools have revealed several essential aspects of monoaminergic involvement in regulating the sleep-wake cycle and influencing sensory responses but many features have remained elusive due to technical limitations. The application of optogenetic tools led to the ability of monitoring and controlling neuronal populations with unprecedented temporal precision and neurochemical specificity. Here, we focus on recent advances in revealing the roles of some monoamines in brain state control and sensory information processing. We summarize the central position of monoamines in integrating sensory processing across sleep-wake states with an emphasis on research conducted using optogenetic techniques. Finally, we discuss the limitations and perspectives of new integrated experimental approaches in understanding the modulatory mechanisms of monoaminergic systems in the mammalian brain.
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15
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Norepinephrine versus dopamine and their interaction in modulating synaptic function in the prefrontal cortex. Brain Res 2016; 1641:217-33. [PMID: 26790349 DOI: 10.1016/j.brainres.2016.01.005] [Citation(s) in RCA: 109] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2015] [Revised: 12/16/2015] [Accepted: 01/05/2016] [Indexed: 01/11/2023]
Abstract
Among the neuromodulators that regulate prefrontal cortical circuit function, the catecholamine transmitters norepinephrine (NE) and dopamine (DA) stand out as powerful players in working memory and attention. Perturbation of either NE or DA signaling is implicated in the pathogenesis of several neuropsychiatric disorders, including attention deficit hyperactivity disorder (ADHD), post-traumatic stress disorder (PTSD), schizophrenia, and drug addiction. Although the precise mechanisms employed by NE and DA to cooperatively control prefrontal functions are not fully understood, emerging research indicates that both transmitters regulate electrical and biochemical aspects of neuronal function by modulating convergent ionic and synaptic signaling in the prefrontal cortex (PFC). This review summarizes previous studies that investigated the effects of both NE and DA on excitatory and inhibitory transmissions in the prefrontal cortical circuitry. Specifically, we focus on the functional interaction between NE and DA in prefrontal cortical local circuitry, synaptic integration, signaling pathways, and receptor properties. Although it is clear that both NE and DA innervate the PFC extensively and modulate synaptic function by activating distinctly different receptor subtypes and signaling pathways, it remains unclear how these two systems coordinate their actions to optimize PFC function for appropriate behavior. Throughout this review, we provide perspectives and highlight several critical topics for future studies. This article is part of a Special Issue entitled SI: Noradrenergic System.
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16
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Komal P, Estakhr J, Kamran M, Renda A, Nashmi R. cAMP-dependent protein kinase inhibits α7 nicotinic receptor activity in layer 1 cortical interneurons through activation of D1/D5 dopamine receptors. J Physiol 2015; 593:3513-32. [PMID: 25990637 DOI: 10.1113/jp270469] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2015] [Accepted: 05/13/2015] [Indexed: 01/11/2023] Open
Abstract
KEY POINTS Protein kinases can modify the function of many proteins including ion channels. However, the role of protein kinase A in modifying nicotinic receptors in the CNS has never been investigated. We showed through whole-cell recordings of layer 1 prefrontal cortical interneurons that α7 nicotinic responses are negatively modulated by protein kinase A. Furthermore, we show that stimulation of dopamine receptors can similarly attenuate α7 nicotinic responses through the activation of protein kinase A. These results suggest how the interaction of the cholinergic and dopaminergic systems may influence neuronal excitability in the brain. ABSTRACT Phosphorylation of ion channels, including nicotinic acetylcholine receptors (nAChRs), by protein kinases plays a key role in the modification of synaptic transmission and neuronal excitability. α7 nAChRs are the second most prevalent nAChR subtype in the CNS following α4β2. Serine 365 in the M3-M4 cytoplasmic loop of the α7 nAChR is a phosphorylation site for protein kinase A (PKA). D1/D5 dopamine receptors signal through the adenylate cyclase-PKA pathway and play a key role in working memory and attention in the prefrontal cortex. Thus, we examined whether the dopaminergic system, mediated through PKA, functionally interacts with the α7-dependent cholinergic neurotransmission. In layer 1 interneurons of mouse prefrontal cortex, α7 nicotinic currents were decreased upon stimulation with 8-Br-cAMP, a PKA activator. In HEK 293T cells, dominant negative PKA abolished 8-Br-cAMP's effect of diminishing α7 nicotinic currents, while a constitutively active PKA catalytic subunit decreased α7 currents. In brain slices, the PKA inhibitor KT-5720 nullified 8-Br-cAMP's effect of attenuating α7 nicotinic responses, while applying a PKA catalytic subunit in the pipette solution decreased α7 currents. 8-Br-cAMP stimulation reduced surface expression of α7 nAChRs, but there was no change in single-channel conductance. The D1/D5 dopamine receptor agonist SKF 83822 similarly attenuated α7 nicotinic currents from layer 1 interneurons and this attenuation of nicotinic current was prevented by KT-5720. These results demonstrate that dopamine receptor-mediated activation of PKA negatively modulates nicotinic neurotransmission in prefrontal cortical interneurons, which may be a contributing mechanism of dopamine modulation of cognitive behaviours such as attention or working memory.
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Affiliation(s)
- Pragya Komal
- Department of Biology, Centre for Biomedical Research, University of Victoria, British Columbia, Canada
| | - Jasem Estakhr
- Department of Biology, Centre for Biomedical Research, University of Victoria, British Columbia, Canada
| | - Melad Kamran
- Department of Biology, Centre for Biomedical Research, University of Victoria, British Columbia, Canada
| | - Anthony Renda
- Department of Biology, Centre for Biomedical Research, University of Victoria, British Columbia, Canada
| | - Raad Nashmi
- Department of Biology, Centre for Biomedical Research, University of Victoria, British Columbia, Canada
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17
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Simulation of the capacity and precision of working memory in the hypodopaminergic state: Relevance to schizophrenia. Neuroscience 2015; 295:80-9. [DOI: 10.1016/j.neuroscience.2015.03.039] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2014] [Revised: 03/01/2015] [Accepted: 03/19/2015] [Indexed: 12/16/2022]
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18
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Werlen E, Jones MW. Modulating the map: dopaminergic tuning of hippocampal spatial coding and interactions. PROGRESS IN BRAIN RESEARCH 2015; 219:187-216. [PMID: 26072240 DOI: 10.1016/bs.pbr.2015.03.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Salient events activate the midbrain dopaminergic system and have important impacts on various aspects of mnemonic function, including the stability of hippocampus-dependent memories. Dopamine is also central to modulation of neocortical memory processing, particularly during prefrontal cortex-dependent working memory. Here, we review the current state of the circuitry and physiology underlying dopamine's actions, suggesting that--alongside local effects within hippocampus and prefrontal cortex--dopamine released from the midbrain ventral tegmental area is well positioned to dynamically tune interactions between limbic-cortical circuits through modulation of rhythmic network activity.
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Affiliation(s)
- Emilie Werlen
- School of Physiology and Pharmacology, University of Bristol, University Walk, Bristol, UK.
| | - Matthew W Jones
- School of Physiology and Pharmacology, University of Bristol, University Walk, Bristol, UK
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19
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Fiore VG, Mannella F, Mirolli M, Latagliata EC, Valzania A, Cabib S, Dolan RJ, Puglisi-Allegra S, Baldassarre G. Corticolimbic catecholamines in stress: a computational model of the appraisal of controllability. Brain Struct Funct 2014; 220:1339-53. [PMID: 24578177 PMCID: PMC4409646 DOI: 10.1007/s00429-014-0727-7] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2013] [Accepted: 02/04/2014] [Indexed: 01/20/2023]
Abstract
Appraisal of a stressful situation and the possibility to control or avoid it is thought to involve frontal-cortical mechanisms. The precise mechanism underlying this appraisal and its translation into effective stress coping (the regulation of physiological and behavioural responses) are poorly understood. Here, we propose a computational model which involves tuning motivational arousal to the appraised stressing condition. The model provides a causal explanation of the shift from active to passive coping strategies, i.e. from a condition characterised by high motivational arousal, required to deal with a situation appraised as stressful, to a condition characterised by emotional and motivational withdrawal, required when the stressful situation is appraised as uncontrollable/unavoidable. The model is motivated by results acquired via microdialysis recordings in rats and highlights the presence of two competing circuits dominated by different areas of the ventromedial prefrontal cortex: these are shown having opposite effects on several subcortical areas, affecting dopamine outflow in the striatum, and therefore controlling motivation. We start by reviewing published data supporting structure and functioning of the neural model and present the computational model itself with its essential neural mechanisms. Finally, we show the results of a new experiment, involving the condition of repeated inescapable stress, which validate most of the model's predictions.
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Affiliation(s)
- Vincenzo G. Fiore
- Wellcome Trust Centre for Neuroimaging, Institute of Neurology, UCL, 12 Queen Square, London, WC1N 3BG UK
| | - Francesco Mannella
- Laboratory of Computational Embodied Neuroscience, Istituto di Scienze e Tecnologie della Cognizione, Consiglio Nazionale delle Ricerche (LOCEN-ISTC-CNR), Via San Martino della Battaglia 44, 00185 Rome, Italy
| | - Marco Mirolli
- Laboratory of Computational Embodied Neuroscience, Istituto di Scienze e Tecnologie della Cognizione, Consiglio Nazionale delle Ricerche (LOCEN-ISTC-CNR), Via San Martino della Battaglia 44, 00185 Rome, Italy
| | - Emanuele Claudio Latagliata
- Dipartimento di Psicologia and Centro Daniel Bovet, Sapienza Università di Roma, Via dei Marsi 78, 00183 Rome, Italy
- Fondazione Santa Lucia, IRCCS, Via Ardeatina 306, 00142 Rome, Italy
| | - Alessandro Valzania
- Dipartimento di Psicologia and Centro Daniel Bovet, Sapienza Università di Roma, Via dei Marsi 78, 00183 Rome, Italy
- Fondazione Santa Lucia, IRCCS, Via Ardeatina 306, 00142 Rome, Italy
| | - Simona Cabib
- Dipartimento di Psicologia and Centro Daniel Bovet, Sapienza Università di Roma, Via dei Marsi 78, 00183 Rome, Italy
- Fondazione Santa Lucia, IRCCS, Via Ardeatina 306, 00142 Rome, Italy
| | - Raymond J. Dolan
- Wellcome Trust Centre for Neuroimaging, Institute of Neurology, UCL, 12 Queen Square, London, WC1N 3BG UK
| | - Stefano Puglisi-Allegra
- Dipartimento di Psicologia and Centro Daniel Bovet, Sapienza Università di Roma, Via dei Marsi 78, 00183 Rome, Italy
- Fondazione Santa Lucia, IRCCS, Via Ardeatina 306, 00142 Rome, Italy
| | - Gianluca Baldassarre
- Laboratory of Computational Embodied Neuroscience, Istituto di Scienze e Tecnologie della Cognizione, Consiglio Nazionale delle Ricerche (LOCEN-ISTC-CNR), Via San Martino della Battaglia 44, 00185 Rome, Italy
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20
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Wang DH, Wong-Lin K. Comodulation of dopamine and serotonin on prefrontal cortical rhythms: a theoretical study. Front Integr Neurosci 2013; 7:54. [PMID: 23935568 PMCID: PMC3733011 DOI: 10.3389/fnint.2013.00054] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2013] [Accepted: 07/08/2013] [Indexed: 12/29/2022] Open
Abstract
The prefrontal cortex (PFC) is implicated to play an important role in cognitive control. Abnormal PFC activities and rhythms have been observed in some neurological and neuropsychiatric disorders, and evidences suggest influences from the neuromodulators dopamine (DA) and serotonin (5-HT). Despite the high level of interest in these brain systems, the combined effects of DA and 5-HT modulation on PFC dynamics remain unknown. In this work, we build a mathematical model that incorporates available experimental findings to systematically study the comodulation of DA and 5-HT on the network behavior, focusing on beta and gamma band oscillations. Single neuronal model shows pyramidal cells with 5-HT1A and 2A receptors can be non-monotonically modulated by 5-HT. Two-population excitatory-inhibitory type network consisting of pyramidal cells with D1 receptors can provide rich repertoires of oscillatory behavior. In particular, 5-HT and DA can modulate the amplitude and frequency of the oscillations, which can emerge or cease, depending on receptor types. Certain receptor combinations are conducive for the robustness of the oscillatory regime, or the existence of multiple discrete oscillatory regimes. In a multi-population heterogeneous model that takes into account possible combination of receptors, we demonstrate that robust network oscillations require high DA concentration. We also show that selective D1 receptor antagonists (agonists) tend to suppress (enhance) network oscillations, increase the frequency from beta toward gamma band, while selective 5-HT1A antagonists (agonists) act in opposite ways. Selective D2 or 5-HT2A receptor antagonists (agonists) can lead to decrease (increase) in oscillation amplitude, but only 5-HT2A antagonists (agonists) can increase (decrease) the frequency. These results are comparable to some pharmacological effects. Our work illustrates the complex mechanisms of DA and 5-HT when operating simultaneously through multiple receptors.
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Affiliation(s)
- Da-Hui Wang
- Department of Systems Science and National Key Laboratory of Cognitive Neuroscience and Learning, Beijing Normal University Beijing, China
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21
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Ahmadi H, Nasehi M, Rostami P, Zarrindast MR. Involvement of the nucleus accumbens shell dopaminergic system in prelimbic NMDA-induced anxiolytic-like behaviors. Neuropharmacology 2013; 71:112-23. [DOI: 10.1016/j.neuropharm.2013.03.017] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2012] [Revised: 03/21/2013] [Accepted: 03/23/2013] [Indexed: 01/21/2023]
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22
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Glucocorticoid-induced enhancement of contextual fear memory consolidation in rats: Involvement of D1 receptor activity of hippocampal area CA1. Brain Res 2013; 1524:26-33. [DOI: 10.1016/j.brainres.2013.05.030] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2012] [Revised: 05/01/2013] [Accepted: 05/19/2013] [Indexed: 01/01/2023]
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23
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Cilz NI, Kurada L, Hu B, Lei S. Dopaminergic modulation of GABAergic transmission in the entorhinal cortex: concerted roles of α1 adrenoreceptors, inward rectifier K⁺, and T-type Ca²⁺ channels. Cereb Cortex 2013; 24:3195-208. [PMID: 23843440 DOI: 10.1093/cercor/bht177] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Whereas the entorhinal cortex (EC) receives profuse dopaminergic innervations from the midbrain, the effects of dopamine (DA) on γ-Aminobutyric acid (GABA)ergic interneurons in this brain region have not been determined. We probed the actions of DA on GABAA receptor-mediated synaptic transmission in the EC. Application of DA increased the frequency, not the amplitude, of spontaneous IPSCs (sIPSCs) and miniature IPSCs (mIPSCs) recorded from entorhinal principal neurons, but slightly reduced the amplitude of the evoked IPSCs. The effects of DA were unexpectedly found to be mediated by α1 adrenoreceptors, but not by DA receptors. DA endogenously released by the application of amphetamine also increased the frequency of sIPSCs. Ca(2+) influx via T-type Ca(2+) channels was required for DA-induced facilitation of sIPSCs and mIPSCs. DA depolarized and enhanced the firing frequency of action potentials of interneurons. DA-induced depolarization was independent of extracellular Na(+) and Ca(2+) and did not require the functions of hyperpolarization-activated (Ih) channels and T-type Ca(2+) channels. DA-generated currents showed a reversal potential close to the K(+) reversal potential and inward rectification, suggesting that DA inhibits the inward rectifier K(+) channels (Kirs). Our results demonstrate that DA facilitates GABA release by activating α1 adrenoreceptors to inhibit Kirs, which further depolarize interneurons resulting in secondary Ca(2+) influx via T-type Ca(+) channels.
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Affiliation(s)
- Nicholas I Cilz
- Department of Pharmacology, Physiology and Therapeutics, School of Medicine and Health Sciences, University of North Dakota, Grand Forks, ND 58203, USA
| | - Lalitha Kurada
- Department of Pharmacology, Physiology and Therapeutics, School of Medicine and Health Sciences, University of North Dakota, Grand Forks, ND 58203, USA
| | - Binqi Hu
- Department of Pharmacology, Physiology and Therapeutics, School of Medicine and Health Sciences, University of North Dakota, Grand Forks, ND 58203, USA
| | - Saobo Lei
- Department of Pharmacology, Physiology and Therapeutics, School of Medicine and Health Sciences, University of North Dakota, Grand Forks, ND 58203, USA
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Furth KE, Mastwal S, Wang KH, Buonanno A, Vullhorst D. Dopamine, cognitive function, and gamma oscillations: role of D4 receptors. Front Cell Neurosci 2013; 7:102. [PMID: 23847468 PMCID: PMC3698457 DOI: 10.3389/fncel.2013.00102] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2013] [Accepted: 06/11/2013] [Indexed: 12/29/2022] Open
Abstract
Cognitive deficits in individuals with schizophrenia (SCZ) are considered core symptoms of this disorder, and can manifest at the prodromal stage. Antipsychotics ameliorate positive symptoms but only modestly improve cognitive symptoms. The lack of treatments that improve cognitive abilities currently represents a major obstacle in developing more effective therapeutic strategies for this debilitating disorder. While D4 receptor (D4R)-specific antagonists are ineffective in the treatment of positive symptoms, animal studies suggest that D4R drugs can improve cognitive deficits. Moreover, recent work from our group suggests that D4Rs synergize with the neuregulin/ErbB4 signaling pathway, genetically identified as risk factors for SCZ, in parvalbumin (PV)-expressing interneurons to modulate gamma oscillations. These high-frequency network oscillations correlate with attention and increase during cognitive tasks in healthy subjects, and this correlation is attenuated in affected individuals. This finding, along with other observations indicating impaired GABAergic function, has led to the idea that abnormal neural activity in the prefrontal cortex (PFC) in individuals with SCZ reflects a perturbation in the balance of excitation and inhibition. Here we review the current state of knowledge of D4R functions in the PFC and hippocampus, two major brain areas implicated in SCZ. Special emphasis is given to studies focusing on the potential role of D4Rs in modulating GABAergic transmission and to an emerging concept of a close synergistic relationship between dopamine/D4R and neuregulin/ErbB4 signaling pathways that tunes the activity of PV interneurons to regulate gamma frequency network oscillations and potentially cognitive processes.
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Affiliation(s)
- Katrina E Furth
- Section on Molecular Neurobiology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health Bethesda, MD, USA ; Graduate Program for Neuroscience, Boston University Boston, MA, USA
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25
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Paul K, Cox CL. Age-dependent actions of dopamine on inhibitory synaptic transmission in superficial layers of mouse prefrontal cortex. J Neurophysiol 2012; 109:1323-32. [PMID: 23221420 DOI: 10.1152/jn.00756.2012] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Numerous developmental changes in the nervous system occur during the first several weeks of the rodent lifespan. Therefore, many characteristics of neuronal function described at the cellular level from in vitro slice experiments conducted during this early time period may not generalize to adult ages. We investigated the effect of dopamine (DA) on inhibitory synaptic transmission in superficial layers of the medial prefrontal cortex (PFC) in prepubertal [postnatal age (P; days) 12-20], periadolescent (P30-48), and adult (P70-100) mice. The PFC is associated with higher-level cognitive functions, such as working memory, and is associated with initiation, planning, and execution of actions, as well as motivation and cognition. It is innervated by DA-releasing fibers that arise from the ventral tegmental area. In slices from prepubertal mice, DA produced a biphasic modulation of inhibitory postsynaptic currents (IPSCs) recorded in layer II/III pyramidal neurons. Activation of D2-like receptors leads to an early suppression of the evoked IPSC, which was followed by a longer-lasting facilitation of the IPSC mediated by D1-like DA receptors. In periadolescent mice, the D2 receptor-mediated early suppression was significantly smaller compared with the prepubertal animals and absent in adult animals. Furthermore, we found significant differences in the DA-mediated lasting enhancement of the inhibitory response among the developmental groups. Our findings suggest that behavioral paradigms that elicit dopaminergic release in the PFC differentially modulate inhibition of excitatory pyramidal neuron output in prepuberty compared with periadolescence and adulthood in the superficial layers (II/III) of the cortex.
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Affiliation(s)
- Kush Paul
- Department of Molecular and Integrative Physiology, Department of Pharmacology, Beckman Institute for Advanced Scienceand Technology, University of Illinois, Urbana, IL, USA.
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26
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Kömek K, Bard Ermentrout G, Walker CP, Cho RY. Dopamine and gamma band synchrony in schizophrenia--insights from computational and empirical studies. Eur J Neurosci 2012; 36:2146-55. [PMID: 22805060 DOI: 10.1111/j.1460-9568.2012.08071.x] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Dopamine modulates cortical circuit activity in part through its actions on GABAergic interneurons, including increasing the excitability of fast-spiking interneurons. Though such effects have been demonstrated in single cells, there are no studies that examine how such mechanisms may lead to the effects of dopamine at a neural network level. With this motivation, we investigated the effects of dopamine on synchronization in a simulated neural network composed of excitatory and fast-spiking inhibitory Wang-Buzsaki neurons. The effects of dopamine were implemented through varying leak K+ conductance of the fast-spiking interneurons and the network synchronization within the gamma band (∼40 Hz) was analyzed. Parametrically varying the leak K+ conductance revealed an inverted-U shaped relationship, with low gamma band power at both low and high conductance levels and optimal synchronization at intermediate conductance levels. We also examined the effects of modulating excitability of the inhibitory neurons more generically using an idealized model with theta neurons, with similar findings. Moreover, such a relationship holds when the external input is both tonic and periodic. Our computational results mirror our empirical study of dopamine modulation in schizophrenia and healthy controls, which showed that amphetamine administration increased gamma power in patients but decreased it in controls. Together, our computational and empirical investigations indicate that dopamine can modulate cortical gamma band synchrony in an inverted-U fashion and that the physiologic effects of dopamine on single fast-spiking interneurons can give rise to such non-monotonic effects at the network level.
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Affiliation(s)
- Kübra Kömek
- Program in Neural Computation, Carnegie Mellon University, Pittsburgh, PA 15289, USA
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Abstract
Among the many neuromodulators used by the mammalian brain to regulate circuit function and plasticity, dopamine (DA) stands out as one of the most behaviorally powerful. Perturbations of DA signaling are implicated in the pathogenesis or exploited in the treatment of many neuropsychiatric diseases, including Parkinson's disease (PD), addiction, schizophrenia, obsessive compulsive disorder, and Tourette's syndrome. Although the precise mechanisms employed by DA to exert its control over behavior are not fully understood, DA is known to regulate many electrical and biochemical aspects of neuronal function including excitability, synaptic transmission, integration and plasticity, protein trafficking, and gene transcription. In this Review, we discuss the actions of DA on ionic and synaptic signaling in neurons of the prefrontal cortex and striatum, brain areas in which dopaminergic dysfunction is thought to be central to disease.
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Affiliation(s)
- Nicolas X Tritsch
- Howard Hughes Medical Institute, Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA
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28
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Retz W, González-Trejo E, Römer KD, Philipp-Wiegmann F, Reinert P, Low YF, Boureghda S, Rösler M, Strauss DJ. Assessment of post-excitatory long-interval cortical inhibition in adult attention-deficit/hyperactivity disorder. Eur Arch Psychiatry Clin Neurosci 2012; 262:507-17. [PMID: 22350621 DOI: 10.1007/s00406-012-0299-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/15/2011] [Accepted: 01/28/2012] [Indexed: 10/28/2022]
Abstract
In order to further examine cortical impairment in adult ADHD patients and to test the hypothesis of a disturbed neuronal inhibition in adults with ADHD, late auditory evoked potentials were measured. By using paired-chirp auditory late responses, we compared 15 adults with ADHD with 15 control subjects, focusing on the inhibition elicited by the stimuli. Besides amplitude measurements, a time-frequency phase coherence study using the wavelet phase synchronization stability (WPSS) was performed. ADHD was diagnosed according to DSM-IV criteria. All ADHD subjects were without medication and did not suffer from any further axis I disorder. WPSS analysis revealed impaired auditory inhibition for ADHD patients for interstimulus intervals (ISI) between 500 and 1,100 ms as compared with healthy controls. By analyzing the WPSS in the interval from 80 ms to 220 ms, mean inhibition of the test chirp was found to be 6% in the ADHD group and 38.5% in the control subjects (p = 0.01). Moreover, overall smaller amplitudes in the N100 and P200 waves at all ISI were found (p = 0.04 and p = 0.02). However, reproducibility indices in the amplitude measurements were low, thus supporting the use of the instantaneous phase-based analysis method. The results support the hypothesis of reduced intracortical inhibition as a correlate of disturbed brain function in adults with ADHD.
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Affiliation(s)
- Wolfgang Retz
- Institute for Forensic Psychology and Psychiatry, Neurocentre, Saarland University Hospital, Bdg. 90.3, 66424, Homburg/Saar, Germany.
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Li YC, Wang MJ, Gao WJ. Hyperdopaminergic modulation of inhibitory transmission is dependent on GSK-3β signaling-mediated trafficking of GABAA receptors. J Neurochem 2012; 122:308-20. [PMID: 22676038 DOI: 10.1111/j.1471-4159.2012.07790.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Cortical dopamine (DA) modulation of the gamma-amino butyric acid (GABA) system is closely associated with cognitive function and psychiatric disorders. We recently reported that the glycogen synthase kinase 3β (GSK-3β) pathway is required for hyperdopamine/D2 receptor-mediated inhibition of NMDA receptors in the prefrontal cortex. Here we explore whether or not GSK-3β is also involved in dopaminergic modulation of GABAA receptor-mediated inhibitory transmission. We confirmed that DA induces a dose-dependent, bidirectional regulatory effect on inhibitory postsynaptic currents (IPSCs) in prefrontal neurons. The modulatory effects of DA were differentially affected by co-application of GSK-3β inhibitors and different doses of DA. GSK-3β inhibitors completely blocked high-dose (20 μM) DA-induced depressive effects on IPSCs but exhibited limited effects on the facilitating regulation of IPSC in low-dose DA (200 nM). We also confirmed that surface expressions of GABAA receptor β2/3 subunits were significantly decreased by DA applied in cultured prefrontal neurons and in vivo administration of DA reuptake inhibitor. These effects were blocked by prior administration of GSK-3β inhibitors. We explored DA-mediated regulation of GABAA receptor trafficking and exhibited the participation of brefeldin A-inhibited GDP/GTP exchange factor 2 (BIG2) or dynamin-dependent trafficking of GABAA receptors. Together, these data suggest that DA may act through different signaling pathways to affect synaptic inhibition, depending on the concentration. The GSK-3β signaling pathway is involved in DA-induced decrease in BIG2-dependent insertion and an increase in the dynamin-dependent internalization of GABAA receptors, which results in suppression of inhibitory synaptic transmission.
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Affiliation(s)
- Yan-Chun Li
- Department of Neurobiology & Anatomy, Drexel University College of Medicine, Philadelphia, Pennsylvania, USA
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Katsuki F, Constantinidis C. Unique and shared roles of the posterior parietal and dorsolateral prefrontal cortex in cognitive functions. Front Integr Neurosci 2012; 6:17. [PMID: 22563310 PMCID: PMC3342558 DOI: 10.3389/fnint.2012.00017] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2012] [Accepted: 04/16/2012] [Indexed: 11/24/2022] Open
Abstract
The dorsolateral prefrontal cortex (PFC) and posterior parietal cortex (PPC) are two parts of a broader brain network involved in the control of cognitive functions such as working-memory, spatial attention, and decision-making. The two areas share many functional properties and exhibit similar patterns of activation during the execution of mental operations. However, neurophysiological experiments in non-human primates have also documented subtle differences, revealing functional specialization within the fronto-parietal network. These differences include the ability of the PFC to influence memory performance, attention allocation, and motor responses to a greater extent, and to resist interference by distracting stimuli. In recent years, distinct cellular and anatomical differences have been identified, offering insights into how functional specialization is achieved. This article reviews the common functions and functional differences between the PFC and PPC, and their underlying mechanisms.
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Affiliation(s)
- Fumi Katsuki
- Department of Neurobiology and Anatomy, Wake Forest University School of Medicine, Winston-Salem NC, USA
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31
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Rothmond DA, Weickert CS, Webster MJ. Developmental changes in human dopamine neurotransmission: cortical receptors and terminators. BMC Neurosci 2012; 13:18. [PMID: 22336227 PMCID: PMC3315415 DOI: 10.1186/1471-2202-13-18] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2011] [Accepted: 02/15/2012] [Indexed: 11/10/2022] Open
Abstract
Background Dopamine is integral to cognition, learning and memory, and dysfunctions of the frontal cortical dopamine system have been implicated in several developmental neuropsychiatric disorders. The dorsolateral prefrontal cortex (DLPFC) is critical for working memory which does not fully mature until the third decade of life. Few studies have reported on the normal development of the dopamine system in human DLPFC during postnatal life. We assessed pre- and postsynaptic components of the dopamine system including tyrosine hydroxylase, the dopamine receptors (D1, D2 short and D2 long isoforms, D4, D5), catechol-O-methyltransferase, and monoamine oxidase (A and B) in the developing human DLPFC (6 weeks -50 years). Results Gene expression was first analysed by microarray and then by quantitative real-time PCR. Protein expression was analysed by western blot. Protein levels for tyrosine hydroxylase peaked during the first year of life (p < 0.001) then gradually declined to adulthood. Similarly, mRNA levels of dopamine receptors D2S (p < 0.001) and D2L (p = 0.003) isoforms, monoamine oxidase A (p < 0.001) and catechol-O-methyltransferase (p = 0.024) were significantly higher in neonates and infants as was catechol-O-methyltransferase protein (32 kDa, p = 0.027). In contrast, dopamine D1 receptor mRNA correlated positively with age (p = 0.002) and dopamine D1 receptor protein expression increased throughout development (p < 0.001) with adults having the highest D1 protein levels (p ≤ 0.01). Monoamine oxidase B mRNA and protein (p < 0.001) levels also increased significantly throughout development. Interestingly, dopamine D5 receptor mRNA levels negatively correlated with age (r = -0.31, p = 0.018) in an expression profile opposite to that of the dopamine D1 receptor. Conclusions We find distinct developmental changes in key components of the dopamine system in DLPFC over postnatal life. Those genes that are highly expressed during the first year of postnatal life may influence and orchestrate the early development of cortical neural circuitry while genes portraying a pattern of increasing expression with age may indicate a role in DLPFC maturation and attainment of adult levels of cognitive function.
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Affiliation(s)
- Debora A Rothmond
- Schizophrenia Research Institute, 405 Liverpool St, Darlinghurst NSW 2010 AU.
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Chronic morphine treatment switches the effect of dopamine on excitatory synaptic transmission from inhibition to excitation in pyramidal cells of the basolateral amygdala. J Neurosci 2012; 31:17527-36. [PMID: 22131414 DOI: 10.1523/jneurosci.3806-11.2011] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Dopaminergic signaling in the basolateral amygdala (BLA) is important for drug-stimulus learning that triggers relapse to drug-seeking behavior. However, little is known about adaptive changes in this signaling pathway upon chronic morphine treatment. In this paper, we observed the influence of chronic morphine treatment on the effect of dopamine (DA) on the excitatory transmission in the pyramidal cells of BLA in slices with the whole-cell patch-clamp method. We also studied its mechanism and significance with pharmacological approaches combined with biochemical and behavioral techniques. The results showed that chronic morphine exposure switched the effect of DA on the excitatory synaptic transmission from inhibition to excitation; the chronic morphine-induced switching action on the effect of DA was due to its influence on D1 receptors; the site of the effect of chronic morphine treatment on D1 receptors was at presynaptic locus; chronic morphine treatment induced a significant increase in the amount of D1 receptor expression in the synaptosomes and synaptosomal membrane fraction from BLA; the enhancement of presynaptic glutamate release by D1 receptor agonist upon chronic morphine treatment was dependent on the activation of cAMP-dependent protein kinase; and the intra-BLA injection of D1 receptor antagonist canceled the conditioned place aversion (CPA) in morphine-dependent rats. In conclusion, chronic morphine treatment switches the effect of DA on the excitatory synaptic transmission from inhibition to excitation by the presynaptic D1 receptor amount increase-mediated glutamate release in the pyramidal cells of BLA and the blockade of D1 receptors in BLA cancels CPA in morphine-dependent rats.
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Abstract
The neurotransmitter GABA (γ-aminobutyric acid), acting via inotropic GABA(A) and metabotropic GABA(B) receptors, plays an essential role in a variety of distinct neuronal processes, including regulation of neuronal excitability, determination of temporal aspects of spike trains, control of the size and propagation of neuronal assemblies, generation of oscillatory activity, and neuronal plasticity. Although the developmental switch between excitatory and inhibitory GABA(A) receptor-mediated responses is widely appreciated, the fact that the postnatal maturation of the GABAergic system lasts until late adolescence is not so persuasively promoted. This review summarizes recent knowledge of the maturation of various aspects of the GABAergic systems, like functional expression of GABA synthesizing/degrading enzymes and transporters, density of GABAergic synapses, GABAergic projection patterns, GABA receptor subunit composition, and properties of GABAergic interneurons, with an emphasis on the late developmental alterations. In addition, some aspects of the development of mental capabilities during adolescence and their relation the delayed maturation of the GABAergic system are presented.
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Affiliation(s)
- Werner Kilb
- Institute of Physiology and Pathophysiology, University Medical Center of the Johannes Gutenberg University, Mainz, Germany.
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34
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Agster KL, Clark BD, Gao WJ, Shumsky JS, Wang HX, Berridge CW, Waterhouse BD. Experimental strategies for investigating psychostimulant drug actions and prefrontal cortical function in ADHD and related attention disorders. Anat Rec (Hoboken) 2011; 294:1698-712. [PMID: 21901844 DOI: 10.1002/ar.21403] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2010] [Revised: 10/26/2010] [Accepted: 02/14/2011] [Indexed: 01/09/2023]
Abstract
Amphetamine-like psychostimulant drugs have been used for decades to treat a variety of clinical conditions. Methylphenidate (MPH)-Ritalin(R) , a compound that blocks reuptake of synaptically released norepinephrine (NE) and dopamine (DA) in the brain, has been used for more than 30 years in low dose, long-term regimens to treat attention deficit-hyperactive disorder (ADHD) in juveniles, adolescents, and adults. Now, these agents are also becoming increasingly popular among healthy individuals from all walks of life (e.g., military, students) and age groups (teenagers thru senior citizens) to promote wakefulness and improve attention. Although there is agreement regarding the primary biochemical action of MPH, the physiological basis for its efficacy in normal individuals and ADHD patients is lacking. Study of the behavioral and physiological actions of clinically and behaviorally relevant doses of MPH in normal animals provides an opportunity to explore the role of catecholamine transmitters in prefrontal cortical function and attentional processes as they relate to normal operation of brain circuits and ADHD pathology. The goal of ongoing studies has been to: (1) assess the effects of low dose MPH on rodent performance in a well characterized sensory-guided sustained attention task, (2) examine the effects of the same low-dose chronic MPH administration on task-related discharge of prefrontal cortical (PFC) neurons, and (3) investigate the effects of NE and DA on membrane response properties and synaptic transmission in identified subsets of PFC neurons. Combinations of these approaches can be used in adolescent, adult, and aged animals to identify the parameters of cell and neural circuit function that are regulated by MPH and to establish an overarching explanation of how MPH impacts PFC operations from cellular through behavioral functional domains.
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Affiliation(s)
- Kara L Agster
- Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, Pennsylvania 19129, USA
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35
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Xue JG, Masuoka T, Gong XD, Chen KS, Yanagawa Y, Law SKA, Konishi S. NMDA receptor activation enhances inhibitory GABAergic transmission onto hippocampal pyramidal neurons via presynaptic and postsynaptic mechanisms. J Neurophysiol 2011; 105:2897-906. [DOI: 10.1152/jn.00287.2010] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
N-methyl-d-aspartate (NMDA) receptors (NMDARs) are implicated in synaptic plasticity and modulation of glutamatergic excitatory transmission. Effect of NMDAR activation on inhibitory GABAergic transmission remains largely unknown. Here, we report that a brief application of NMDA could induce two distinct actions in CA1 pyramidal neurons in mouse hippocampal slices: 1) an inward current attributed to activation of postsynaptic NMDARs; and 2) fast phasic synaptic currents, namely spontaneous inhibitory postsynaptic currents (sIPSCs), mediated by GABAA receptors in pyramidal neurons. The mean amplitude of sIPSCs was also increased by NMDA. This profound increase in the sIPSC frequency and amplitude was markedly suppressed by the sodium channel blocker TTX, whereas the frequency and mean amplitude of miniature IPSCs were not significantly affected by NMDA, suggesting that NMDA elicits repetitive firing in GABAergic interneurons, thereby leading to GABA release from multiple synaptic sites of single GABAergic axons. We found that the NMDAR open-channel blocker MK-801 injected into recorded pyramidal neurons suppressed the NMDA-induced increase of sIPSCs, which raises the possibility that the firing of interneurons may not be the sole factor and certain retrograde messengers may also be involved in the NMDA-mediated enhancement of GABAergic transmission. Our results from pharmacological tests suggest that the nitric oxide signaling pathway is mobilized by NMDAR activation in CA1 pyramidal neurons, which in turn retrogradely facilitates GABA release from the presynaptic terminals. Thus NMDARs at glutamatergic synapses on both CA1 pyramidal neurons and interneurons appear to exert feedback and feedforward inhibition for determining the spike timing of the hippocampal microcircuit.
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Affiliation(s)
- Jiu-Gang Xue
- Department of Neurophysiology, Kagawa School of Pharmaceutical Sciences and Institute of Neuroscience, Tokushima Bunri University, Kagawa, Japan
- School of Biological Sciences, Nanyang Technological University; and
| | - Takayoshi Masuoka
- Department of Neurophysiology, Kagawa School of Pharmaceutical Sciences and Institute of Neuroscience, Tokushima Bunri University, Kagawa, Japan
| | - Xian-Di Gong
- School of Biological Sciences, Nanyang Technological University; and
- Institute of Microelectronics, Agency for Science, Technology, and Research (A*STAR), Singapore; and
| | - Ken-Shiung Chen
- School of Biological Sciences, Nanyang Technological University; and
| | - Yuchio Yanagawa
- Department of Genetic and Behavioral Neuroscience, Gunma University Graduate School of Medicine, Maebashi, Japan
| | - S. K. Alex Law
- School of Biological Sciences, Nanyang Technological University; and
| | - Shiro Konishi
- Department of Neurophysiology, Kagawa School of Pharmaceutical Sciences and Institute of Neuroscience, Tokushima Bunri University, Kagawa, Japan
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36
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Geerts H. Mechanistic disease modeling as a useful tool for improving CNS drug research and development. Drug Dev Res 2010. [DOI: 10.1002/ddr.20403] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Hugo Geerts
- In Silico Biosciences, Berwyn, Pennsylvania
- University of Pennsylvania, School of Medicine, Philadelphia, Pennsylvania
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37
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Moore AR, Zhou WL, Potapenko ES, Kim EJ, Antic SD. Brief dopaminergic stimulations produce transient physiological changes in prefrontal pyramidal neurons. Brain Res 2010; 1370:1-15. [PMID: 21059342 DOI: 10.1016/j.brainres.2010.10.111] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2010] [Revised: 10/24/2010] [Accepted: 10/30/2010] [Indexed: 10/18/2022]
Abstract
In response to food reward and other pertinent events, midbrain dopaminergic neurons fire short bursts of action potentials causing a phasic release of dopamine in the prefrontal cortex (rapid and transient increases in cortical dopamine concentration). Here we apply short (2s) iontophoretic pulses of glutamate, GABA, dopamine and dopaminergic agonists locally, onto layer 5 pyramidal neurons in brain slices of the rat medial prefrontal cortex (PFC). Unlike glutamate and GABA, brief dopaminergic pulses had negligible effects on the resting membrane potential. However, dopamine altered action potential firing in an extremely rapid (<1s) and transient (<5 min) manner, as every neuron returned to baseline in less than 5-min post-application. The physiological responses to dopamine differed markedly among individual neurons. Pyramidal neurons with a preponderance of D1-like receptor signaling respond to dopamine with a severe depression in action potential firing rate, while pyramidal neurons dominated by the D2 signaling pathway respond to dopamine with an instantaneous increase in spike production. Increasing levels of dopamine concentrations around the cell body resulted in a dose dependent response, which resembles an "inverted U curve" (Vijayraghavan S, Wang M, Birnbaum SG, Williams GV, Arnsten AF (2007) Inverted-U dopamine D1 receptor actions on prefrontal neurons engaged in working memory. Nat Neurosci 10:376-384), but this effect can easily be caused by an iontophoresis current artifact. Our present data imply that one population of PFC pyramidal neurons receiving direct synaptic contacts from midbrain dopaminergic neurons would stall during the 0.5s of the phasic dopamine burst. The spillover dopamine, on the other hand, would act as a positive stimulator of cortical excitability (30% increase) to all D2-receptor carrying pyramidal cells, for the next 40s.
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Affiliation(s)
- Anna R Moore
- Department of Neuroscience, University of Connecticut Health Center, 263 Farmington Avenue, Farmington, CT 06030, USA
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38
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Lukhanina E, Berezetskaya N, Karaban I. Paired-pulse inhibition in the auditory cortex in Parkinson's disease and its dependence on clinical characteristics of the patients. PARKINSONS DISEASE 2010; 2011:342151. [PMID: 21052541 PMCID: PMC2968419 DOI: 10.4061/2011/342151] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/24/2010] [Revised: 09/16/2010] [Accepted: 09/29/2010] [Indexed: 01/17/2023]
Abstract
We aimed to determine the value of the paired-pulse inhibition (PPI) in the auditory cortex in patients with Parkinson's disease (PD) and analyze its dependence on clinical characteristics of the patients. The central (Cz) auditory evoked potentials were recorded in 58 patients with PD and 22 age-matched healthy subjects. PPI of the N1/P2 component was significantly (P < .001) reduced for interstimulus intervals 500, 700, and 900 ms in patients with PD compared to control subjects. The value of PPI correlated negatively with the age of the PD patients (P < .05), age of disease onset (P < .05), body bradykinesia score (P < .01), and positively with the Mini Mental State Examination (MMSE) cognitive score (P < .01). Negative correlation between value of PPI and the age of the healthy subjects (P < .05) was also observed. Thus, results show that cortical inhibitory processes are deficient in PD patients and that the brain's ability to carry out the postexcitatory inhibition is age-dependent.
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Affiliation(s)
- Elena Lukhanina
- Department of Brain Physiology, Bogomoletz Institute of Physiology, 01024 Kiev, Ukraine
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39
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Altered dopamine modulation of inhibition in the prefrontal cortex of cocaine-sensitized rats. Neuropsychopharmacology 2010; 35:2292-304. [PMID: 20664581 PMCID: PMC2939941 DOI: 10.1038/npp.2010.107] [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] [Indexed: 11/08/2022]
Abstract
A functionally hypoactive prefrontal cortex (PFC) is thought to contribute to decreased cognitive inhibitory control over drug-seeking behavior in cocaine addicts. Alterations in PFC dopamine (DA) and γ-aminobutyric acid (GABA) transmission are involved in the development of behavioral sensitization to cocaine, and repeated exposure to cocaine decreases DA D2 receptor (D2R) function in the PFC. We used recordings in PFC slices from adult rats to investigate how repeated cocaine treatment followed by 2 weeks of withdrawal affects DA modulation of GABA transmission and interneuron firing. In agreement with previous results in drug-naïve animals we found that in saline-treated control animals DA (20 μM) modulated evoked inhibitory post-synaptic currents (eIPSCs) in a biphasic, time- and receptor-dependent manner. Activation of D2Rs transiently reduced, whereas D1 receptor activation persistently increased the amplitude of eIPSCs. In cocaine-sensitized animals the D2R-dependent modulation of eIPSCs was abolished and the time course of DA effects was altered. In both saline- and cocaine-treated animals the effects of DA on eIPSCs were paralleled by distinct changes in spontaneous IPSCs (sIPSCs). In cocaine-treated animals the alterations in DA modulation of eIPSCs and sIPSCs correlated with a lack of D2R-specific reduction in action potential-independent GABA release, which might normally oppose D1-dependent increases in GABA transmission. Recordings from interneurons furthermore show that D2R activation can increase current-evoked spike firing in saline, but not in cocaine-treated animals. Altered DA regulation of inhibition during cocaine withdrawal could disturb normal cortical processing and contribute to a hypoactive PFC.
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40
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Lanoue AC, Dumitriu A, Myers RH, Soghomonian JJ. Decreased glutamic acid decarboxylase mRNA expression in prefrontal cortex in Parkinson's disease. Exp Neurol 2010; 226:207-17. [PMID: 20832408 DOI: 10.1016/j.expneurol.2010.09.001] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2010] [Revised: 08/27/2010] [Accepted: 09/01/2010] [Indexed: 10/19/2022]
Abstract
Parkinson's disease (PD) patients typically suffer from motor disorders but mild to severe cognitive deficits can also be present. Neuropathology of PD primarily involves loss of dopaminergic neurons in the substantia nigra, pars compacta, although more widespread pathology from the brainstem to the cerebral cortex occurs at different stages of the disease. Cognitive deficits in PD are thought to involve the cerebral cortex, and imaging studies have identified the dorsolateral prefrontal cortex (DLPFC) as a possible site for some of the symptoms. GABAergic neurons in the cerebral cortex play a key role in the modulation of pyramidal neurons and alterations in muscimol binding to GABA(A) receptors have been reported in Brodmann area 9 (BA9) of the prefrontal cortex in PD patients (Nishino et al., 1988). In order to further assess the likelihood that GABAergic activity is altered in the prefrontal cortex in PD, gene expression of the 67 kilodalton isoform of the GABA-synthesizing enzyme, glutamic acid decarboxylase (GAD67 encoded by the GAD1 gene), was examined in BA9 of post-mortem brains from 19 patients and 20 controls using isotopic in situ hybridization histochemistry. GAD67 mRNA labeling was examined and quantified on X-ray films and emulsion radioautographs. We show that GAD67 mRNA labeling is significantly lower in PD compared to control cases. Analysis of emulsion radioautographs indicates that GAD67 mRNA labeling is decreased in individual neurons and is not paralleled by a decrease in the number of GAD67 mRNA-labeled neurons. Analysis of expression data from a microarray study performed in 29 control and 33 PD samples from BA9 confirms that GAD67 expression is decreased in PD. Another finding from the microarray study is a negative relationship between GAD67 mRNA expression and age at death. Altogether, the results support the possibility that GABAergic neurotransmission is impaired in the DLPFC in PD, an effect that may be involved in some of the behavioral deficits associated with the disease.
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Affiliation(s)
- Amélie C Lanoue
- Department of Anatomy and Neurobiology, Boston University School of Medicine, Boston, Massachusetts, 02118, USA
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41
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D1 and D2 dopamine receptors in separate circuits cooperate to drive associative long-term potentiation in the prefrontal cortex. Proc Natl Acad Sci U S A 2010; 107:16366-71. [PMID: 20805489 DOI: 10.1073/pnas.1004108107] [Citation(s) in RCA: 98] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Dopamine release associated with motivational arousal is thought to drive goal-directed learning and consolidation of acquired memories. This dopamine hypothesis of learning and motivation directly suggests that dopamine is necessary for modifications of excitatory synapses in dopamine terminal fields, including the prefrontal cortex (PFC), to "stamp in" posttrial memory traces. It is unknown how such enabling occurs in native circuits tightly controlled by GABAergic inhibitory tone. Here we report that dopamine, via both D1-class receptors (D1Rs) and D2-class receptors (D2Rs), enables the induction of spike timing-dependent long-term potentiation (t-LTP) in layer V PFC pyramidal neurons over a "window" of more than 30 ms that is otherwise closed under intact inhibitory constraint. Dopamine acts at D2Rs in local GABAergic interneurons to suppress inhibitory transmission, gating the induction of t-LTP. Moreover, dopamine activates postsynaptic D1Rs in excitatory synapses to allow t-LTP induction at a substantially extended, normally ineffective, timing interval (+30 ms), thus increasing the associability of prepost coincident stimuli. Although the D2R-mediated disinhibition alone is sufficient to gate t-LTP at a normal timing (+10 ms), t-LTP at +30 ms requires concurrent activation of both D1Rs and D2Rs. Our results illustrate a previously unrecognized circuit-level mechanism by which dopamine receptors in separate microcircuits cooperate to drive Hebbian synaptic plasticity across a significant temporal window under intact inhibition. This mechanism should be important in functioning of interconnected PFC microcircuits, in which D1Rs and D2Rs are not colocalized but their coactivation is necessary.
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42
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Chu HY, Yang Z, Zhao B, Jin GZ, Hu GY, Zhen X. Activation of phosphatidylinositol-linked D1-like receptors increases spontaneous glutamate release in rat somatosensory cortical neurons in vitro. Brain Res 2010; 1343:20-7. [DOI: 10.1016/j.brainres.2010.04.043] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2010] [Revised: 04/15/2010] [Accepted: 04/18/2010] [Indexed: 11/29/2022]
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43
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Nitsche MA, Monte-Silva K, Kuo MF, Paulus W. Dopaminergic Impact on Cortical Excitability in Humans. Rev Neurosci 2010; 21:289-98. [DOI: 10.1515/revneuro.2010.21.4.289] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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44
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van Albada SJ, Robinson PA. Mean-field modeling of the basal ganglia-thalamocortical system. I Firing rates in healthy and parkinsonian states. J Theor Biol 2008; 257:642-63. [PMID: 19168074 DOI: 10.1016/j.jtbi.2008.12.018] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2008] [Revised: 12/08/2008] [Accepted: 12/08/2008] [Indexed: 01/02/2023]
Abstract
Parkinsonism leads to various electrophysiological changes in the basal ganglia-thalamocortical system (BGTCS), often including elevated discharge rates of the subthalamic nucleus (STN) and the output nuclei, and reduced activity of the globus pallidus external (GPe) segment. These rate changes have been explained qualitatively in terms of the direct/indirect pathway model, involving projections of distinct striatal populations to the output nuclei and GPe. Although these populations partly overlap, evidence suggests dopamine depletion differentially affects cortico-striato-pallidal connection strengths to the two pallidal segments. Dopamine loss may also decrease the striatal signal-to-noise ratio, reducing both corticostriatal coupling and striatal firing thresholds. Additionally, nigrostriatal degeneration may cause secondary changes including weakened lateral inhibition in the GPe, and mesocortical dopamine loss may decrease intracortical excitation and especially inhibition. Here a mean-field model of the BGTCS is presented with structure and parameter estimates closely based on physiology and anatomy. Changes in model rates due to the possible effects of dopamine loss listed above are compared with experiment. Our results suggest that a stronger indirect pathway, possibly combined with a weakened direct pathway, is compatible with empirical evidence. However, altered corticostriatal connection strengths are probably not solely responsible for substantially increased STN activity often found. A lower STN firing threshold, weaker intracortical inhibition, and stronger striato-GPe inhibition help explain the relatively large increase in STN rate. Reduced GPe-GPe inhibition and a lower GPe firing threshold can account for the comparatively small decrease in GPe rate frequently observed. Changes in cortex, GPe, and STN help normalize the cortical rate, also in accord with experiments. The model integrates the basal ganglia into a unified framework along with an existing thalamocortical model that already accounts for a wide range of electrophysiological phenomena. A companion paper discusses the dynamics and oscillations of this combined system.
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Affiliation(s)
- S J van Albada
- School of Physics, The University of Sydney, New South Wales 2006, Australia.
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45
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Mean-field modeling of the basal ganglia-thalamocortical system. II Dynamics of parkinsonian oscillations. J Theor Biol 2008; 257:664-88. [PMID: 19154745 DOI: 10.1016/j.jtbi.2008.12.013] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2008] [Revised: 12/08/2008] [Accepted: 12/08/2008] [Indexed: 11/21/2022]
Abstract
Neuronal correlates of Parkinson's disease (PD) include a shift to lower frequencies in the electroencephalogram (EEG) and enhanced synchronized oscillations at 3-7 and 7-30 Hz in the basal ganglia, thalamus, and cortex. This study describes the dynamics of a recent physiologically based mean-field model of the basal ganglia-thalamocortical system, and shows how it accounts for many key electrophysiological correlates of PD. Its detailed functional connectivity comprises partially segregated direct and indirect pathways through two populations of striatal neurons, a hyperdirect pathway involving a corticosubthalamic projection, thalamostriatal feedback, and local inhibition in striatum and external pallidum (GPe). In a companion paper, realistic steady-state firing rates were obtained for the healthy state, and after dopamine loss modeled by weaker direct and stronger indirect pathways, reduced intrapallidal inhibition, lower firing thresholds of the GPe and subthalamic nucleus (STN), a stronger projection from striatum to GPe, and weaker cortical interactions. Here it is shown that oscillations around 5 and 20 Hz can arise with a strong indirect pathway, which also causes increased synchronization throughout the basal ganglia. Furthermore, increased theta power with progressive nigrostriatal degeneration is correlated with reduced alpha power and peak frequency, in agreement with empirical results. Unlike the hyperdirect pathway, the indirect pathway sustains oscillations with phase relationships that coincide with those found experimentally. Alterations in the responses of basal ganglia to transient stimuli accord with experimental observations. Reduced cortical gains due to both nigrostriatal and mesocortical dopamine loss lead to slower changes in cortical activity and may be related to bradykinesia. Finally, increased EEG power found in some studies may be partly explained by a lower effective GPe firing threshold, reduced GPe-GPe inhibition, and/or weaker intracortical connections in parkinsonian patients. Strict separation of the direct and indirect pathways is not necessary to obtain these results.
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A low dimensional description of globally coupled heterogeneous neural networks of excitatory and inhibitory neurons. PLoS Comput Biol 2008; 4:e1000219. [PMID: 19008942 PMCID: PMC2574034 DOI: 10.1371/journal.pcbi.1000219] [Citation(s) in RCA: 90] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2008] [Accepted: 09/30/2008] [Indexed: 11/19/2022] Open
Abstract
Neural networks consisting of globally coupled excitatory and inhibitory nonidentical neurons may exhibit a complex dynamic behavior including synchronization, multiclustered solutions in phase space, and oscillator death. We investigate the conditions under which these behaviors occur in a multidimensional parametric space defined by the connectivity strengths and dispersion of the neuronal membrane excitability. Using mode decomposition techniques, we further derive analytically a low dimensional description of the neural population dynamics and show that the various dynamic behaviors of the entire network can be well reproduced by this reduced system. Examples of networks of FitzHugh-Nagumo and Hindmarsh-Rose neurons are discussed in detail. Nowadays we know that most cognitive functions are not represented in the brain by the activation of a single area but rather by a complex and rich behavior of brain networks distributed over various cortical and subcortical areas. The communication between brain areas is not instantaneous but also undergoes significant signal transmission delays of up to 100 ms, which increase the computation time for brain network models enormously. In order to allow the efficient investigation of brain network models and their associated cognitive capabilities, we report here a novel, computationally parsimonious, mathematical representation of clusters of neurons. Such reduced clusters are called “neural masses” and serve as nodes in the brain networks. Traditional neural mass descriptions so far allowed only for a very limited repertoire of behaviors, which ultimately rendered their description biologically unrealistic. The neural mass model presented here overcomes this limitation and captures a wide range of dynamic behaviors, but in a computationally efficient reduced form. The integration of novel neural mass models into brain networks represents a step closer toward a computational and biologically realistic realization of brain function.
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Lavigne F, Darmon N. Dopaminergic neuromodulation of semantic priming in a cortical network model. Neuropsychologia 2008; 46:3074-87. [DOI: 10.1016/j.neuropsychologia.2008.06.019] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2008] [Revised: 05/24/2008] [Accepted: 06/27/2008] [Indexed: 12/22/2022]
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Santana N, Mengod G, Artigas F. Quantitative analysis of the expression of dopamine D1 and D2 receptors in pyramidal and GABAergic neurons of the rat prefrontal cortex. Cereb Cortex 2008; 19:849-60. [PMID: 18689859 DOI: 10.1093/cercor/bhn134] [Citation(s) in RCA: 172] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Mesocortical dopamine (DA) is a key neurotransmitter in cognitive processes and is involved in schizophrenia and antipsychotic drug action. DA exerts a highly complex modulation of network activity in prefrontal cortex (PFC), possibly due to the recruitment of multiple signaling pathways and to specialized cellular localizations of DA receptors in cortical microcircuits. Using double in situ hybridization, we quantitatively assessed the expression of D(1) and D(2) receptor messenger RNAs (mRNAs) in pyramidal and gamma-aminobutyric acidergic (GABAergic) neurons of rat PFC. The proportion of pyramidal and GABA cells expressing these transcripts shows great regional variability in PFC, with little overlap (layer V). More pyramidal and GABA cells express D(1) than D(2) receptors. D(1) receptors are expressed by a greater proportion of GABA than pyramidal neurons, yet the number of D(1)-positive pyramidal cells outnumbers D(1)-positive interneurons due to the greater abundance of pyramidal neurons. Occasional PFC cells show high levels of mRNA, similar to those in striatal neurons. Finally, pyramidal and GABAergic cells expressing the same transcript were almost never found in close apposition, yet D(2)-containing pyramidal neurons were often found close to non-D(2) GABA neurons. Thus, cellular and network DA actions in PFC are region and layer specific and may depend on precise cellular interactions.
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Affiliation(s)
- Noemí Santana
- Department of Neurochemistry and Neuropharmacology, Institut d' Investigacions Biomèdiques de Barcelona, Spain
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Witkowski G, Szulczyk B, Rola R, Szulczyk P. D1 dopaminergic control of G protein–dependent inward rectifier K+ (GIRK)–like channel current in pyramidal neurons of the medial prefrontal cortex. Neuroscience 2008; 155:53-63. [DOI: 10.1016/j.neuroscience.2008.05.021] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2008] [Revised: 05/13/2008] [Accepted: 05/14/2008] [Indexed: 10/22/2022]
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Abstract
Inhibitory control of local neuronal circuits is critical for prefrontal cortical functioning. Modulation of inhibitory circuits by several neuromodulators has been demonstrated, but the underlying mechanisms are unclear. Neuromodulator effects on synaptic vesicle recycling have received little attention. Controversy also exists whether different pools of synaptic vesicles underlie spontaneous and activity-dependent vesicle recycling. We therefore investigated the effects of kainate receptor activation on GABA release in rat prefrontal neocortex using electrophysiological and styryl dye imaging techniques in acute neocortical slices. Electrophysiological studies demonstrated that activation of kainate receptors increased the frequency, but not the amplitude of miniature IPSCs, suggesting a presynaptic action. Using styryl dye staining and multiphoton excitation microscopy, we visualized vesicular release from inhibitory GABAergic terminals in prefrontal cortical slices and demonstrate that kainate facilitates GABA release from presynaptic terminals. Our findings also indicate the presence of two pools of GABA-containing vesicles within inhibitory terminals. Kainate modulates both pools but only when vesicles are endocytosed and exocytosed by matching protocols of dye loading, i.e., spontaneous or evoked afferent activity.
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