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Zheng J, Peng S, Cui L, Liu X, Li T, Zhao Z, Li Y, Hu Y, Zhang M, Xu L, Zhang J. Enriched environment attenuates hippocampal theta and gamma rhythms dysfunction in chronic cerebral hypoperfusion via improving imbalanced neural afferent levels. Front Cell Neurosci 2023; 17:985246. [PMID: 37265581 PMCID: PMC10231328 DOI: 10.3389/fncel.2023.985246] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2022] [Accepted: 02/27/2023] [Indexed: 06/03/2023] Open
Abstract
Chronic cerebral hypoperfusion (CCH) is increasingly recognized as a common cognitive impairment-causing mechanism. However, no clinically effective drugs to treat cognitive impairment due to CCH have been identified. An abnormal distribution of neural oscillations was found in the hippocampus of CCH rats. By releasing various neurotransmitters, distinct afferent fibers in the hippocampus influence neuronal oscillations in the hippocampus. Enriched environments (EE) are known to improve cognitive levels by modulating neurotransmitter homeostasis. Using EE as an intervention, we examined the levels of three classical neurotransmitters and the dynamics of neural oscillations in the hippocampus of the CCH rat model. The results showed that EE significantly improved the balance of three classical neurotransmitters (acetylcholine, glutamate, and GABA) in the hippocampus, enhanced the strength of theta and slow-gamma (SG) rhythms, and dramatically improved neural coupling across frequency bands in CCH rats. Furthermore, the expression of the three neurotransmitter vesicular transporters-vesicular acetylcholine transporters (VAChT) and vesicular GABA transporters (VGAT)-was significantly reduced in CCH rats, whereas the expression of vesicular glutamate transporter 1 (VGLUT1) was abnormally elevated. EE partially restored the expression of the three protein levels to maintain the balance of hippocampal afferent neurotransmitters. More importantly, causal mediation analysis showed EE increased the power of theta rhythm by increasing the level of VAChT and VGAT, which then enhanced the phase amplitude coupling of theta-SG and finally led to an improvement in the cognitive level of CCH. These findings shed light on the role of CCH in the disruption of hippocampal afferent neurotransmitter balance and neural oscillations. This study has implications for our knowledge of disease pathways.
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Affiliation(s)
- Jiaxin Zheng
- Department of Neurology, Zhongnan Hospital of Wuhan University, Wuhan, China
| | - Sisi Peng
- Department of Neurology, Zhongnan Hospital of Wuhan University, Wuhan, China
| | - Lingling Cui
- Department of Anesthesiology, Tongren Hospital of Wuhan University, Wuhan, China
| | - Xi Liu
- Department of Neurology, Zhongnan Hospital of Wuhan University, Wuhan, China
| | - Tian Li
- Clinical Medical Research Center for Dementia and Cognitive Impairment in Hubei Province, Wuhan, China
| | - Zhenyu Zhao
- Clinical Medical Research Center for Dementia and Cognitive Impairment in Hubei Province, Wuhan, China
| | - Yaqing Li
- Clinical Medical Research Center for Dementia and Cognitive Impairment in Hubei Province, Wuhan, China
| | - Yuan Hu
- Department of Neurology, Zhongnan Hospital of Wuhan University, Wuhan, China
| | - Miao Zhang
- Department of Neurology, Zhongnan Hospital of Wuhan University, Wuhan, China
| | - Linling Xu
- Clinical Medical Research Center for Dementia and Cognitive Impairment in Hubei Province, Wuhan, China
| | - JunJian Zhang
- Department of Neurology, Zhongnan Hospital of Wuhan University, Wuhan, China
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Márquez LA, Griego E, López Rubalcava C, Galván EJ. NMDA receptor activity during postnatal development determines intrinsic excitability and mossy fiber long-term potentiation of CA3 pyramidal cells. Hippocampus 2023. [PMID: 36938755 DOI: 10.1002/hipo.23524] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2022] [Revised: 01/30/2023] [Accepted: 02/23/2023] [Indexed: 03/21/2023]
Abstract
Experimental manipulations that interfere with the functional expression of N-methyl-D-aspartate receptors (NMDARs) during prenatal neurodevelopment or critical periods of postnatal development are models that mimic behavioral and neurophysiological abnormalities of schizophrenia. Blockade of NMDARs with MK-801 during early postnatal development alters glutamate release and impairs the induction of NMDAR-dependent long-term plasticity at the CA1 area of the hippocampus. However, it remains unknown if other forms of hippocampal plasticity, such as α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR)-mediated short- and long-term potentiation, are compromised in response to neonatal treatment with MK-801. Consistent with this tenet, short- and long-term potentiation between dentate gyrus axons, the mossy fibers (MF), onto CA3 pyramidal cells (CA3 PCs) are mediated by AMPARs. By combining whole-cell patch clamp and extracellular recordings, we have demonstrated that transient blockade of NMDARs during early postnatal development induces a series of pre- and postsynaptic modifications at the MF-CA3 synapse. We found reduced glutamate release from the mossy boutons, increased paired-pulse ratio, and reduced AMPAR-mediated MF LTP levels. At the postsynaptic level, we found an altered NMDA/AMPA ratio and dysregulation of several potassium conductances that increased the excitability of CA3 PCs. In addition, MK-801-treated animals exhibited impaired spatial memory retrieval in the Barnes maze task. Our data demonstrate that transient hypofunction of NMDARs impacts NMDAR-independent forms of synaptic plasticity of the hippocampus.
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Affiliation(s)
- Luis A Márquez
- Departamento de Farmacobiología, CINVESTAV Unidad Sur, Ciudad de México, Mexico
| | - Ernesto Griego
- Departamento de Farmacobiología, CINVESTAV Unidad Sur, Ciudad de México, Mexico
| | | | - Emilio J Galván
- Departamento de Farmacobiología, CINVESTAV Unidad Sur, Ciudad de México, Mexico.,Centro de Investigaciones sobre el Envejecimiento, CIE-Cinvestav, Ciudad de México, Mexico
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Zinchenko VP, Kosenkov AM, Gaidin SG, Sergeev AI, Dolgacheva LP, Tuleukhanov ST. Properties of GABAergic Neurons Containing Calcium-Permeable Kainate and AMPA-Receptors. Life (Basel) 2021; 11:life11121309. [PMID: 34947840 PMCID: PMC8705177 DOI: 10.3390/life11121309] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2021] [Revised: 11/23/2021] [Accepted: 11/25/2021] [Indexed: 12/12/2022] Open
Abstract
Calcium-permeable kainate and AMPA receptors (CP-KARs and CP-AMPARs), as well as NMDARs, play a pivotal role in plasticity and in regulating neurotransmitter release. Here we visualized in the mature hippocampal neuroglial cultures the neurons expressing CP-AMPARs and CP-KARs. These neurons were visualized by a characteristic fast sustained [Ca2+]i increase in response to the agonist of these receptors, domoic acid (DoA), and a selective agonist of GluK1-containing KARs, ATPA. Neurons from both subpopulations are GABAergic. The subpopulation of neurons expressing CP-AMPARs includes a larger percentage of calbindin-positive neurons (39.4 ± 6.0%) than the subpopulation of neurons expressing CP-KARs (14.2 ± 7.5% of CB+ neurons). In addition, we have shown for the first time that NH4Cl-induced depolarization faster induces an [Ca2+]i elevation in GABAergic neurons expressing CP-KARs and CP-AMPARs than in most glutamatergic neurons. CP-AMPARs antagonist, NASPM, increased the amplitude of the DoA-induced Ca2+ response in GABAergic neurons expressing CP-KARs, indicating that neurons expressing CP-AMPARs innervate GABAergic neurons expressing CP-KARs. We assume that CP-KARs in inhibitory neurons are involved in the mechanism of outstripping GABA release upon hyperexcitation.
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Affiliation(s)
- Valery Petrovich Zinchenko
- Federal Research Center “Pushchino Scientific Center for Biological Research of the Russian Academy of Sciences”, Institute of Cell Biophysics of the Russian Academy of Sciences, 142290 Pushchino, Russia; (A.M.K.); (S.G.G.); (A.I.S.); (L.P.D.)
- Correspondence:
| | - Artem Mikhailovich Kosenkov
- Federal Research Center “Pushchino Scientific Center for Biological Research of the Russian Academy of Sciences”, Institute of Cell Biophysics of the Russian Academy of Sciences, 142290 Pushchino, Russia; (A.M.K.); (S.G.G.); (A.I.S.); (L.P.D.)
| | - Sergei Gennadevich Gaidin
- Federal Research Center “Pushchino Scientific Center for Biological Research of the Russian Academy of Sciences”, Institute of Cell Biophysics of the Russian Academy of Sciences, 142290 Pushchino, Russia; (A.M.K.); (S.G.G.); (A.I.S.); (L.P.D.)
| | - Alexander Igorevich Sergeev
- Federal Research Center “Pushchino Scientific Center for Biological Research of the Russian Academy of Sciences”, Institute of Cell Biophysics of the Russian Academy of Sciences, 142290 Pushchino, Russia; (A.M.K.); (S.G.G.); (A.I.S.); (L.P.D.)
| | - Ludmila Petrovna Dolgacheva
- Federal Research Center “Pushchino Scientific Center for Biological Research of the Russian Academy of Sciences”, Institute of Cell Biophysics of the Russian Academy of Sciences, 142290 Pushchino, Russia; (A.M.K.); (S.G.G.); (A.I.S.); (L.P.D.)
| | - Sultan Tuleukhanovich Tuleukhanov
- Laboratory of Biophysics, Chronobiology and Biomedicine, Faculty of Biology and Biotechnology, Al-Farabi Kazakh National University, Almaty 050040, Kazakhstan;
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Negrete-Díaz JV, Falcón-Moya R, Rodríguez-Moreno A. Kainate receptors: from synaptic activity to disease. FEBS J 2021; 289:5074-5088. [PMID: 34143566 DOI: 10.1111/febs.16081] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Revised: 05/18/2021] [Accepted: 06/17/2021] [Indexed: 12/30/2022]
Abstract
Kainate receptors (KARs) are glutamate receptors that participate in the postsynaptic transmission of information and in the control of neuronal excitability, as well as presynaptically modulating the release of the neurotransmitters GABA and glutamate. These modulatory effects, general follow a biphasic pattern, with low KA concentrations provoking an increase in GABA and glutamate release, and higher concentrations mediating a decrease in the release of these neurotransmitters. In addition, KARs are involved in different forms of long- and short-term plasticity. Importantly, altered activity of these receptors has been implicated in different central nervous system diseases and disturbances. Here, we describe the pre- and postsynaptic actions of KARs, and the possible role of these receptors in disease, a field that has seen significant progress in recent years.
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Affiliation(s)
- José Vicente Negrete-Díaz
- Laboratory of Cellular Neuroscience and Plasticity, Department of Physiology, Anatomy and Cell Biology, Universidad Pablo de Olavide, Sevilla, Spain.,Laboratorio de Psicología Experimental y Neurociencias, División de Ciencias de la Salud e Ingenierías, Universidad de Guanajuato, México
| | - Rafael Falcón-Moya
- Laboratory of Cellular Neuroscience and Plasticity, Department of Physiology, Anatomy and Cell Biology, Universidad Pablo de Olavide, Sevilla, Spain
| | - Antonio Rodríguez-Moreno
- Laboratory of Cellular Neuroscience and Plasticity, Department of Physiology, Anatomy and Cell Biology, Universidad Pablo de Olavide, Sevilla, Spain
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Kosenkov AM, Teplov IY, Sergeev AI, Maiorov SA, Zinchenko VP, Gaidin SG. Domoic acid suppresses hyperexcitation in the network due to activation of kainate receptors of GABAergic neurons. Arch Biochem Biophys 2019; 671:52-61. [DOI: 10.1016/j.abb.2019.06.004] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2019] [Revised: 06/12/2019] [Accepted: 06/15/2019] [Indexed: 01/01/2023]
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Subburaju S, Coleman AJ, Cunningham MG, Ruzicka WB, Benes FM. Epigenetic Regulation of Glutamic Acid Decarboxylase 67 in a Hippocampal Circuit. Cereb Cortex 2017; 27:5284-5293. [PMID: 27733539 PMCID: PMC6411031 DOI: 10.1093/cercor/bhw307] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2016] [Revised: 08/25/2016] [Accepted: 09/11/2016] [Indexed: 01/05/2023] Open
Abstract
GABAergic dysfunction in hippocampus, a key feature of schizophrenia (SZ), may contribute to cognitive impairment in this disorder. In stratum oriens (SO) of sector CA3/2 of the human hippocampus, a network of genes involved in the regulation of glutamic acid decarboxylase GAD67 has been identified. Several of the genes in this network including epigenetic factors histone deacetylase 1 (HDAC1) and death-associated protein 6 (DAXX), the GABAergic enzyme GAD65 as well as the kainate receptor (KAR) subunits GluR6 and 7 show significant changes in expression in this area in SZ. We have tested whether HDAC1 and DAXX regulate GAD67, GAD65, or GluR in the intact rodent hippocampus. Stereotaxic injections of lentiviral vectors bearing shRNAi sequences for HDAC1 and DAXX were delivered into the SO of CA3/2, followed by laser microdissection of individual transduced GABA neurons. Quantitative PCR (QPCR) analyses demonstrated that inhibition of HDAC1 and DAXX increased expression of GAD67, GAD65, and GluR6 mRNA. Inhibition of DAXX, but not HDAC1 resulted in a significant increase in GluR7 mRNA. Our data support the hypothesis that HDAC1 and DAXX play a central role in coordinating the expression of genes in the GAD67 regulatory pathway in the SO of CA3/2.
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MESH Headings
- Adaptor Proteins, Signal Transducing/antagonists & inhibitors
- Adaptor Proteins, Signal Transducing/metabolism
- Animals
- CA2 Region, Hippocampal/cytology
- CA2 Region, Hippocampal/metabolism
- CA3 Region, Hippocampal/cytology
- CA3 Region, Hippocampal/metabolism
- Cell Line
- Epigenesis, Genetic
- GABAergic Neurons/cytology
- GABAergic Neurons/metabolism
- Glutamate Decarboxylase/metabolism
- Histone Deacetylase 1/antagonists & inhibitors
- Histone Deacetylase 1/metabolism
- Male
- Molecular Chaperones
- Neural Pathways/cytology
- Neural Pathways/metabolism
- Nuclear Proteins/antagonists & inhibitors
- Nuclear Proteins/metabolism
- RNA, Messenger/metabolism
- Rats, Sprague-Dawley
- Receptors, Glutamate/metabolism
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Affiliation(s)
- Sivan Subburaju
- Program in Structural and Molecular Neuroscience, McLean
Hospital, Belmont, MA 02478,
USA
- Department of Psychiatry, Harvard Medical School, Boston, MA 02115,
USA
| | - Andrew J Coleman
- Program in Structural and Molecular Neuroscience, McLean
Hospital, Belmont, MA 02478,
USA
| | - Miles G Cunningham
- Program in Structural and Molecular Neuroscience, McLean
Hospital, Belmont, MA 02478,
USA
- Department of Psychiatry, Harvard Medical School, Boston, MA 02115,
USA
| | - W Brad Ruzicka
- Program in Structural and Molecular Neuroscience, McLean
Hospital, Belmont, MA 02478,
USA
- Department of Psychiatry, Harvard Medical School, Boston, MA 02115,
USA
| | - Francine M Benes
- Program in Structural and Molecular Neuroscience, McLean
Hospital, Belmont, MA 02478,
USA
- Department of Psychiatry, Harvard Medical School, Boston, MA 02115,
USA
- Program in Neuroscience, Harvard Medical
School, Boston, MA 02115,
USA
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7
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Abstract
Postmortem studies have suggested that there is abnormal GABAergic activity in the hippocampus in schizophrenia (SZ). In micro-dissected human hippocampal slices, a loss of interneurons and a compensatory upregulation of GABAA receptor binding activity on interneurons, but not PNs, has suggested that disinhibitory GABA-to-GABA connections are abnormal in stratum oriens (SO) of CA3/2, but not CA1, in schizophrenia. Abnormal expression changes in the expression of kainate receptor (KAR) subunits 5, 6 and 7, as well as an inwardly-rectifying hyperpolarization-activated cationic channel (Ih3; HCN3) may play important roles in regulating GABA cell activity at the SO CA3/2 locus. The exclusive neurons at this site are GABAergic interneurons; these cells also receive direct projections from the basolateral amygdala (BLA). When the BLA is stimulated by stereotaxic infusion of picrotoxin in rats, KARs influence axodendritic and presynaptic inhibitory mechanisms that regulate both inhibitory and disinhibitory interneurons in the SO-CA3/2 locus. The rat model described here was specifically developed to extend our understanding of these and other postmortem findings and has suggested that GABAergic abnormalities and possible disturbances in oscillatory rhythms may be related to a dysfunction of disinhibitory interneurons at the SO-CA3/2 site of schizophrenics.
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Affiliation(s)
- Francine M Benes
- Program in Structural and Molecular Neuroscience and Harvard Brain Tissue Resource Center, McLean Hospital, Belmont, MA, USA; Department of Psychiatry and Program in Neuroscience, Harvard Medical School, Boston, MA, USA.
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Miller SL, Aroniadou-Anderjaska V, Figueiredo TH, Prager EM, Almeida-Suhett CP, Apland JP, Braga MFM. A rat model of nerve agent exposure applicable to the pediatric population: The anticonvulsant efficacies of atropine and GluK1 antagonists. Toxicol Appl Pharmacol 2015; 284:204-16. [PMID: 25689173 DOI: 10.1016/j.taap.2015.02.008] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2014] [Revised: 01/30/2015] [Accepted: 02/07/2015] [Indexed: 12/27/2022]
Abstract
Inhibition of acetylcholinesterase (AChE) after nerve agent exposure induces status epilepticus (SE), which causes brain damage or death. The development of countermeasures appropriate for the pediatric population requires testing of anticonvulsant treatments in immature animals. In the present study, exposure of 21-day-old (P21) rats to different doses of soman, followed by probit analysis, produced an LD50 of 62μg/kg. The onset of behaviorally-observed SE was accompanied by a dramatic decrease in brain AChE activity; rats who did not develop SE had significantly less reduction of AChE activity in the basolateral amygdala than rats who developed SE. Atropine sulfate (ATS) at 2mg/kg, administered 20 min after soman exposure (1.2×LD50), terminated seizures. ATS at 0.5mg/kg, given along with an oxime within 1 min after exposure, allowed testing of anticonvulsants at delayed time-points. The AMPA/GluK1 receptor antagonist LY293558, or the specific GluK1 antagonist UBP302, administered 1h post-exposure, terminated SE. There were no degenerating neurons in soman-exposed P21 rats, but both the amygdala and the hippocampus were smaller than in control rats at 30 and 90days post-exposure; this pathology was not present in rats treated with LY293558. Behavioral deficits present at 30 days post-exposure, were also prevented by LY293558 treatment. Thus, in immature animals, a single injection of atropine is sufficient to halt nerve agent-induced seizures, if administered timely. Testing anticonvulsants at delayed time-points requires early administration of ATS at a low dose, sufficient to counteract only peripheral toxicity. LY293558 administered 1h post-exposure, prevents brain pathology and behavioral deficits.
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Affiliation(s)
- Steven L Miller
- Department of Anatomy, Physiology, and Genetics, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814, USA; Program in Neuroscience, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814, USA.
| | - Vassiliki Aroniadou-Anderjaska
- Department of Anatomy, Physiology, and Genetics, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814, USA; Department of Psychiatry, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814, USA; Program in Neuroscience, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814, USA.
| | - Taiza H Figueiredo
- Department of Anatomy, Physiology, and Genetics, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814, USA.
| | - Eric M Prager
- Department of Anatomy, Physiology, and Genetics, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814, USA; Program in Neuroscience, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814, USA.
| | - Camila P Almeida-Suhett
- Department of Anatomy, Physiology, and Genetics, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814, USA; Program in Neuroscience, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814, USA.
| | - James P Apland
- Neurotoxicology Branch, U.S. Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD 21010, USA.
| | - Maria F M Braga
- Department of Anatomy, Physiology, and Genetics, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814, USA; Department of Psychiatry, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814, USA; Program in Neuroscience, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814, USA.
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Andersson R, Johnston A, Fisahn A. Dopamine D4 receptor activation increases hippocampal gamma oscillations by enhancing synchronization of fast-spiking interneurons. PLoS One 2012; 7:e40906. [PMID: 22815864 PMCID: PMC3398948 DOI: 10.1371/journal.pone.0040906] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2012] [Accepted: 06/14/2012] [Indexed: 12/28/2022] Open
Abstract
Background Gamma oscillations are electric activity patterns of the mammalian brain hypothesized to serve attention, sensory perception, working memory and memory encoding. They are disrupted or altered in schizophrenic patients with associated cognitive deficits, which persist in spite of treatment with antipsychotics. Because cognitive symptoms are a core feature of schizophrenia it is relevant to explore signaling pathways that potentially regulate gamma oscillations. Dopamine has been reported to decrease gamma oscillation power via D1-like receptors. Based on the expression pattern of D4 receptors (D4R) in hippocampus, and pharmacological effects of D4R ligands in animals, we hypothesize that they are in a position to regulate gamma oscillations as well. Methodology/Principal Findings To address this hypothesis we use rat hippocampal slices and kainate-induced gamma oscillations. Local field potential recordings as well as intracellular recordings of pyramidal cells, fast-spiking and non-fast-spiking interneurons were carried out. We show that D4R activation with the selective ligand PD168077 increases gamma oscillation power, which can be blocked by the D4R-specific antagonist L745,870 as well as by the antipsychotic drug Clozapine. Pyramidal cells did not exhibit changes in excitatory or inhibitory synaptic current amplitudes, but inhibitory currents became more coherent with the oscillations after application of PD168077. Fast-spiking, but not non-fast spiking, interneurons, increase their action potential phase-coupling and coherence with regard to ongoing gamma oscillations in response to D4R activation. Among several possible mechanisms we found that the NMDA receptor antagonist AP5 also blocks the D4R mediated increase in gamma oscillation power. Conclusions/Significance We conclude that D4R activation affects fast-spiking interneuron synchronization and thereby increases gamma power by an NMDA receptor-dependent mechanism. This suggests that converging deficits on fast-spiking interneurons may lead to decreased network function and thus aberrant gamma oscillations and cognitive decline in schizophrenia.
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Affiliation(s)
- Richard Andersson
- Neuronal Oscillations Laboratory, KI-Alzheimer Disease Research Center, Department of Neurobiology, Care Sciences and Society, Karolinska Institute, Stockholm, Sweden
| | - April Johnston
- Neuronal Oscillations Laboratory, KI-Alzheimer Disease Research Center, Department of Neurobiology, Care Sciences and Society, Karolinska Institute, Stockholm, Sweden
| | - André Fisahn
- Neuronal Oscillations Laboratory, KI-Alzheimer Disease Research Center, Department of Neurobiology, Care Sciences and Society, Karolinska Institute, Stockholm, Sweden
- * E-mail:
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