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Thumu SCR, Jain M, Soman S, Das S, Verma V, Nandi A, Gutmann DH, Jayaprakash B, Nair D, Clement JP, Marathe S, Ramanan N. SRF-deficient astrocytes provide neuroprotection in mouse models of excitotoxicity and neurodegeneration. eLife 2024; 13:e95577. [PMID: 38289036 PMCID: PMC10857791 DOI: 10.7554/elife.95577] [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: 12/27/2023] [Accepted: 01/15/2024] [Indexed: 02/10/2024] Open
Abstract
Reactive astrogliosis is a common pathological hallmark of CNS injury, infection, and neurodegeneration, where reactive astrocytes can be protective or detrimental to normal brain functions. Currently, the mechanisms regulating neuroprotective astrocytes and the extent of neuroprotection are poorly understood. Here, we report that conditional deletion of serum response factor (SRF) in adult astrocytes causes reactive-like hypertrophic astrocytes throughout the mouse brain. These SrfGFAP-ERCKO astrocytes do not affect neuron survival, synapse numbers, synaptic plasticity or learning and memory. However, the brains of Srf knockout mice exhibited neuroprotection against kainic-acid induced excitotoxic cell death. Relevant to human neurodegenerative diseases, SrfGFAP-ERCKO astrocytes abrogate nigral dopaminergic neuron death and reduce β-amyloid plaques in mouse models of Parkinson's and Alzheimer's disease, respectively. Taken together, these findings establish SRF as a key molecular switch for the generation of reactive astrocytes with neuroprotective functions that attenuate neuronal injury in the setting of neurodegenerative diseases.
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Affiliation(s)
| | - Monika Jain
- Centre for Neuroscience, Indian Institute of ScienceBangaloreIndia
| | - Sumitha Soman
- Centre for Neuroscience, Indian Institute of ScienceBangaloreIndia
| | - Soumen Das
- Centre for Neuroscience, Indian Institute of ScienceBangaloreIndia
| | - Vijaya Verma
- Neuroscience Unit, Jawaharlal Nehru Centre for Advanced Scientific ResearchBangaloreIndia
| | - Arnab Nandi
- Centre for Neuroscience, Indian Institute of ScienceBangaloreIndia
| | - David H Gutmann
- Department of Neurology, Washington University School of MedicineSt. LouisUnited States
| | | | - Deepak Nair
- Centre for Neuroscience, Indian Institute of ScienceBangaloreIndia
| | - James P Clement
- Neuroscience Unit, Jawaharlal Nehru Centre for Advanced Scientific ResearchBangaloreIndia
| | - Swananda Marathe
- Centre for Neuroscience, Indian Institute of ScienceBangaloreIndia
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2
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Meftah S, Gan J. Alzheimer’s disease as a synaptopathy: Evidence for dysfunction of synapses during disease progression. Front Synaptic Neurosci 2023; 15:1129036. [PMID: 36970154 PMCID: PMC10033629 DOI: 10.3389/fnsyn.2023.1129036] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2022] [Accepted: 02/23/2023] [Indexed: 03/11/2023] Open
Abstract
The synapse has consistently been considered a vulnerable and critical target within Alzheimer’s disease, and synapse loss is, to date, one of the main biological correlates of cognitive decline within Alzheimer’s disease. This occurs prior to neuronal loss with ample evidence that synaptic dysfunction precedes this, in support of the idea that synaptic failure is a crucial stage within disease pathogenesis. The two main pathological hallmarks of Alzheimer’s disease, abnormal aggregates of amyloid or tau proteins, have had demonstrable effects on synaptic physiology in animal and cellular models of Alzheimer’s disease. There is also growing evidence that these two proteins may have a synergistic effect on neurophysiological dysfunction. Here, we review some of the main findings of synaptic alterations in Alzheimer’s disease, and what we know from Alzheimer’s disease animal and cellular models. First, we briefly summarize some of the human evidence to suggest that synapses are altered, including how this relates to network activity. Subsequently, animal and cellular models of Alzheimer’s disease are considered, highlighting mouse models of amyloid and tau pathology and the role these proteins may play in synaptic dysfunction, either in isolation or examining how the two pathologies may interact in dysfunction. This specifically focuses on neurophysiological function and dysfunction observed within these animal models, typically measured using electrophysiology or calcium imaging. Following synaptic dysfunction and loss, it would be impossible to imagine that this would not alter oscillatory activity within the brain. Therefore, this review also discusses how this may underpin some of the aberrant oscillatory patterns seen in animal models of Alzheimer’s disease and human patients. Finally, an overview of some key directions and considerations in the field of synaptic dysfunction in Alzheimer’s disease is covered. This includes current therapeutics that are targeted specifically at synaptic dysfunction, but also methods that modulate activity to rescue aberrant oscillatory patterns. Other important future avenues of note in this field include the role of non-neuronal cell types such as astrocytes and microglia, and mechanisms of dysfunction independent of amyloid and tau in Alzheimer’s disease. The synapse will certainly continue to be an important target within Alzheimer’s disease for the foreseeable future.
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Affiliation(s)
- Soraya Meftah
- UK Dementia Research Institute, The University of Edinburgh, Edinburgh, United Kingdom
- Centre for Discovery Brain Sciences, The University of Edinburgh, Edinburgh, United Kingdom
| | - Jian Gan
- UK Dementia Research Institute, The University of Edinburgh, Edinburgh, United Kingdom
- Centre for Discovery Brain Sciences, The University of Edinburgh, Edinburgh, United Kingdom
- *Correspondence: Jian Gan,
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Verma V, Kumar MJV, Sharma K, Rajaram S, Muddashetty R, Manjithaya R, Behnisch T, Clement JP. Pharmacological intervention in young adolescents rescues synaptic physiology and behavioural deficits in Syngap1 +/- mice. Exp Brain Res 2021; 240:289-309. [PMID: 34739555 DOI: 10.1007/s00221-021-06254-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2021] [Accepted: 10/21/2021] [Indexed: 01/04/2023]
Abstract
Haploinsufficiency in SYNGAP1 is implicated in intellectual disability (ID) and autism spectrum disorder (ASD) and affects the maturation of dendritic spines. The abnormal spine development has been suggested to cause a disbalance of excitatory and inhibitory (E/I) neurotransmission at distinct developmental periods. In addition, E/I imbalances in Syngap1+/- mice might be due to abnormalities in K+-Cl- co-transporter function (NKCC1, KCC2), in a maner similar to the murine models of Fragile-X and Rett syndromes. To study whether an altered intracellular chloride ion concentration represents an underlying mechanism of modified function of GABAergic synapses in Dentate Gyrus Granule Cells of Syngap1+/- recordings were performed at different developmental stages of the mice. We observed depolarised neurons at P14-15 as illustrated by decreased Cl- reversal potential in Syngap1+/- mice. The KCC2 expression was decreased compared to Wild-type (WT) mice at P14-15. The GSK-3β inhibitor, 6-bromoindirubin-3'-oxime (6BIO) that crosses the blood-brain barrier, was tested to restore the function of GABAergic synapses. We discovered that the intraperitoneal administration of 6BIO during the critical period or young adolescents [P30 to P80 (4-week to 10-week)] normalised an altered E/I balance, the deficits of synaptic plasticity, and behavioural performance like social novelty, anxiety, and memory of the Syngap1+/- mice. In summary, altered GABAergic function in Syngap1+/- mice is due to reduced KCC2 expression leading to an increase in the intracellular chloride concentration that can be counteracted by the 6BIO, which restored cognitive, emotional, and social symptoms by pharmacological intervention, particularly in adulthood.
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Affiliation(s)
- Vijaya Verma
- Neuroscience Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore, 560064, India
| | - M J Vijay Kumar
- Neuroscience Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore, 560064, India
| | - Kavita Sharma
- International Centre for Material Sciences, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore, 560064, India
| | - Sridhar Rajaram
- International Centre for Material Sciences, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore, 560064, India
| | - Ravi Muddashetty
- Institute for Stem Cell Biology and Regenerative Medicine, Bangalore, 560065, India
| | - Ravi Manjithaya
- Neuroscience Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore, 560064, India.,Molecular Biology and Genetics Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore, 560064, India
| | - Thomas Behnisch
- Institutes of Brain Sciences, Fudan University, Shanghai, 200032, China
| | - James P Clement
- Neuroscience Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore, 560064, India.
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4
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Percelay S, Billard JM, Freret T, Andrieux A, Boulouard M, Bouet V. Functional Dysregulations in CA1 Hippocampal Networks of a 3-Hit Mouse Model of Schizophrenia. Int J Mol Sci 2021; 22:2644. [PMID: 33807989 PMCID: PMC7961987 DOI: 10.3390/ijms22052644] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2021] [Revised: 03/01/2021] [Accepted: 03/02/2021] [Indexed: 12/12/2022] Open
Abstract
For a better translation from treatment designs of schizophrenia to clinical efficiency, there is a crucial need to refine preclinical animal models. In order to consider the multifactorial nature of the disorder, a new mouse model associating three factors (genetic susceptibility-partial deletion of the MAP6 gene, early-life stress-maternal separation, and pharmacological treatment-chronic Δ-9-tetrahydrocannabinol during adolescence) has recently been described. While this model depicts a schizophrenia-like phenotype, the neurobiological correlates remain unknown. Synaptic transmission and functional plasticity of the CA1 hippocampal region of male and female 3-hit mice were therefore investigated using electrophysiological recordings on the hippocampus slice. While basal excitatory transmission remained unaffected, NMDA receptor (NMDAr)-mediated long-term potentiation (LTP) triggered by theta-burst (TBS) but not by high-frequency (HFS) stimulation was impaired in 3-hit mice. Isolated NMDAr activation was not affected or even increased in female 3-hit mice, revealing a sexual dimorphism. Considering that the regulation of LTP is more prone to inhibitory tone if triggered by TBS than by HFS, the weaker potentiation in 3-hit mice suggests a deficiency of intrinsic GABA regulatory mechanisms. Indeed, NMDAr activation was increased by GABAA receptor blockade in wild-type but not in 3-hit mice. This electrophysiological study highlights dysregulations of functional properties and plasticity in hippocampal networks of 3-hit mice, one of the mechanisms suspected to contribute to the pathophysiology of schizophrenia. It also shows differences between males and females, supporting the sexual dimorphism observed in the disorder. Combined with the previously reported study, the present data reinforce the face validity of the 3-hit model that will help to consider new therapeutic strategies for psychosis.
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Affiliation(s)
- Solenn Percelay
- UNICAEN, INSERM, COMETE, CYCERON, CHU Caen, Normandie Université, 14000 Caen, France; (J.-M.B.); (T.F.); (M.B.); (V.B.)
| | - Jean-Marie Billard
- UNICAEN, INSERM, COMETE, CYCERON, CHU Caen, Normandie Université, 14000 Caen, France; (J.-M.B.); (T.F.); (M.B.); (V.B.)
| | - Thomas Freret
- UNICAEN, INSERM, COMETE, CYCERON, CHU Caen, Normandie Université, 14000 Caen, France; (J.-M.B.); (T.F.); (M.B.); (V.B.)
| | - Annie Andrieux
- Inserm U1216, CEA, Grenoble Institut Neurosciences, Université Grenoble Alpes, 38000 Grenoble, France;
| | - Michel Boulouard
- UNICAEN, INSERM, COMETE, CYCERON, CHU Caen, Normandie Université, 14000 Caen, France; (J.-M.B.); (T.F.); (M.B.); (V.B.)
| | - Valentine Bouet
- UNICAEN, INSERM, COMETE, CYCERON, CHU Caen, Normandie Université, 14000 Caen, France; (J.-M.B.); (T.F.); (M.B.); (V.B.)
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5
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Murphy E, Benítez-Burraco A. Toward the Language Oscillogenome. Front Psychol 2018; 9:1999. [PMID: 30405489 PMCID: PMC6206218 DOI: 10.3389/fpsyg.2018.01999] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2018] [Accepted: 09/28/2018] [Indexed: 12/20/2022] Open
Abstract
Language has been argued to arise, both ontogenetically and phylogenetically, from specific patterns of brain wiring. We argue that it can further be shown that core features of language processing emerge from particular phasal and cross-frequency coupling properties of neural oscillations; what has been referred to as the language ‘oscillome.’ It is expected that basic aspects of the language oscillome result from genetic guidance, what we will here call the language ‘oscillogenome,’ for which we will put forward a list of candidate genes. We have considered genes for altered brain rhythmicity in conditions involving language deficits: autism spectrum disorders, schizophrenia, specific language impairment and dyslexia. These selected genes map on to aspects of brain function, particularly on to neurotransmitter function. We stress that caution should be adopted in the construction of any oscillogenome, given the range of potential roles particular localized frequency bands have in cognition. Our aim is to propose a set of genome-to-language linking hypotheses that, given testing, would grant explanatory power to brain rhythms with respect to language processing and evolution.
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Affiliation(s)
- Elliot Murphy
- Division of Psychology and Language Sciences, University College London, London, United Kingdom.,Department of Psychology, University of Westminster, London, United Kingdom
| | - Antonio Benítez-Burraco
- Department of Spanish Language, Linguistics and Literary Theory, University of Seville, Seville, Spain
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6
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Tropea D, Hardingham N, Millar K, Fox K. Mechanisms underlying the role of DISC1 in synaptic plasticity. J Physiol 2018; 596:2747-2771. [PMID: 30008190 PMCID: PMC6046077 DOI: 10.1113/jp274330] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2017] [Accepted: 02/02/2018] [Indexed: 12/11/2022] Open
Abstract
Disrupted in schizophrenia 1 (DISC1) is an important hub protein, forming multimeric complexes by self-association and interacting with a large number of synaptic and cytoskeletal molecules. The synaptic location of DISC1 in the adult brain suggests a role in synaptic plasticity, and indeed, a number of studies have discovered synaptic plasticity impairments in a variety of different DISC1 mutants. This review explores the possibility that DISC1 is an important molecule for organizing proteins involved in synaptic plasticity and examines why mutations in DISC1 impair plasticity. It concentrates on DISC1's role in interacting with synaptic proteins, controlling dendritic structure and cellular trafficking of mRNA, synaptic vesicles and mitochondria. N-terminal directed mutations appear to impair synaptic plasticity through interactions with phosphodiesterase 4B (PDE4B) and hence protein kinase A (PKA)/GluA1 and PKA/cAMP response element-binding protein (CREB) signalling pathways, and affect spine structure through interactions with kalirin 7 (Kal-7) and Rac1. C-terminal directed mutations also impair plasticity possibly through altered interactions with lissencephaly protein 1 (LIS1) and nuclear distribution protein nudE-like 1 (NDEL1), thereby affecting developmental processes such as dendritic structure and spine maturation. Many of the same molecules involved in DISC1's cytoskeletal interactions are also involved in intracellular trafficking, raising the possibility that impairments in intracellular trafficking affect cytoskeletal development and vice versa. While the multiplicity of DISC1 protein interactions makes it difficult to pinpoint a single causal signalling pathway, we suggest that the immediate-term effects of N-terminal influences on GluA1, Rac1 and CREB, coupled with the developmental effects of C-terminal influences on trafficking and the cytoskeleton make up the two main branches of DISC1's effect on synaptic plasticity and dendritic spine stability.
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Affiliation(s)
- Daniela Tropea
- Neurospychiatric GeneticsTrinity Center for Health Sciences and Trinity College Institute of Neuroscience (TCIN)Trinity College DublinDublinIreland
| | - Neil Hardingham
- School of BiosciencesMuseum AvenueCardiff UniversityCardiffUK
| | - Kirsty Millar
- Centre for Genomic & Experimental MedicineMRC Institute of Genetics & Molecular MedicineWestern General HospitalUniversity of EdinburghCrewe RoadEdinburghUK
| | - Kevin Fox
- School of BiosciencesMuseum AvenueCardiff UniversityCardiffUK
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7
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Tamagnini F, Walsh DA, Brown JT, Bondulich MK, Hanger DP, Randall AD. Hippocampal neurophysiology is modified by a disease-associated C-terminal fragment of tau protein. Neurobiol Aging 2017; 60:44-56. [PMID: 28917666 PMCID: PMC5654728 DOI: 10.1016/j.neurobiolaging.2017.07.005] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2017] [Revised: 05/26/2017] [Accepted: 07/11/2017] [Indexed: 01/09/2023]
Abstract
The accumulation of cleaved tau fragments in the brain is associated with several tauopathies. For this reason, we recently developed a transgenic mouse that selectively accumulates a C-Terminal 35 kDa human tau fragment (Tau35). These animals develop progressive motor and spatial memory impairment, paralleled by increased hippocampal glycogen synthase kinase 3β activity. In this neurophysiological study, we focused on the CA1 subfield of the hippocampus, a brain area involved in memory encoding. The accumulation of Tau35 results in a significant increase of short-term facilitation of the synaptic response in the theta frequency range (10 Hz), without affecting basal synaptic transmission and long-term synaptic plasticity. Tau35 expression also alters the intrinsic excitability of CA1 pyramidal neurons. Thus, Tau35 presence is associated with increased and decreased excitability at hyperpolarized and depolarized potentials, respectively. These observations are paralleled by a hyperpolarization of the voltage-sensitivity of noninactivating K+ currents. Further investigation is needed to assess the causal link between such functional alterations and the cognitive and motor impairments previously observed in this model.
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Affiliation(s)
- Francesco Tamagnini
- Institute of Clinical and Biomedical Sciences, University of Exeter Medical School, University of Exeter, Exeter, UK.
| | - Darren A Walsh
- Institute of Clinical and Biomedical Sciences, University of Exeter Medical School, University of Exeter, Exeter, UK
| | - Jon T Brown
- Institute of Clinical and Biomedical Sciences, University of Exeter Medical School, University of Exeter, Exeter, UK
| | - Marie K Bondulich
- King's College London, Institute of Psychiatry, Psychology & Neuroscience, Maurice Wohl Clinical Neuroscience Institute, London, UK
| | - Diane P Hanger
- King's College London, Institute of Psychiatry, Psychology & Neuroscience, Maurice Wohl Clinical Neuroscience Institute, London, UK
| | - Andrew D Randall
- Institute of Clinical and Biomedical Sciences, University of Exeter Medical School, University of Exeter, Exeter, UK
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8
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Ruggiero RN, Rossignoli MT, De Ross JB, Hallak JEC, Leite JP, Bueno-Junior LS. Cannabinoids and Vanilloids in Schizophrenia: Neurophysiological Evidence and Directions for Basic Research. Front Pharmacol 2017; 8:399. [PMID: 28680405 PMCID: PMC5478733 DOI: 10.3389/fphar.2017.00399] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2017] [Accepted: 06/06/2017] [Indexed: 01/14/2023] Open
Abstract
Much of our knowledge of the endocannabinoid system in schizophrenia comes from behavioral measures in rodents, like prepulse inhibition of the acoustic startle and open-field locomotion, which are commonly used along with neurochemical approaches or drug challenge designs. Such methods continue to map fundamental mechanisms of sensorimotor gating, hyperlocomotion, social interaction, and underlying monoaminergic, glutamatergic, and GABAergic disturbances. These strategies will require, however, a greater use of neurophysiological tools to better inform clinical research. In this sense, electrophysiology and viral vector-based circuit dissection, like optogenetics, can further elucidate how exogenous cannabinoids worsen (e.g., tetrahydrocannabinol, THC) or ameliorate (e.g., cannabidiol, CBD) schizophrenia symptoms, like hallucinations, delusions, and cognitive deficits. Also, recent studies point to a complex endocannabinoid-endovanilloid interplay, including the influence of anandamide (endogenous CB1 and TRPV1 agonist) on cognitive variables, such as aversive memory extinction. In fact, growing interest has been devoted to TRPV1 receptors as promising therapeutic targets. Here, these issues are reviewed with an emphasis on the neurophysiological evidence. First, we contextualize imaging and electrographic findings in humans. Then, we present a comprehensive review on rodent electrophysiology. Finally, we discuss how basic research will benefit from further combining psychopharmacological and neurophysiological tools.
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Affiliation(s)
- Rafael N Ruggiero
- Department of Neuroscience and Behavioral Sciences, Ribeirão Preto Medical School, University of São PauloRibeirão Preto, Brazil
| | - Matheus T Rossignoli
- Department of Neuroscience and Behavioral Sciences, Ribeirão Preto Medical School, University of São PauloRibeirão Preto, Brazil
| | - Jana B De Ross
- Department of Neuroscience and Behavioral Sciences, Ribeirão Preto Medical School, University of São PauloRibeirão Preto, Brazil
| | - Jaime E C Hallak
- Department of Neuroscience and Behavioral Sciences, Ribeirão Preto Medical School, University of São PauloRibeirão Preto, Brazil.,National Institute for Science and Technology-Translational Medicine, National Council for Scientific and Technological Development (CNPq)Ribeirão Preto, Brazil
| | - Joao P Leite
- Department of Neuroscience and Behavioral Sciences, Ribeirão Preto Medical School, University of São PauloRibeirão Preto, Brazil
| | - Lezio S Bueno-Junior
- Department of Neuroscience and Behavioral Sciences, Ribeirão Preto Medical School, University of São PauloRibeirão Preto, Brazil
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9
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Walsh DA, Brown JT, Randall AD. In vitro characterization of cell-level neurophysiological diversity in the rostral nucleus reuniens of adult mice. J Physiol 2017; 595:3549-3572. [PMID: 28295330 PMCID: PMC5451734 DOI: 10.1113/jp273915] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2016] [Accepted: 03/09/2017] [Indexed: 12/15/2022] Open
Abstract
KEY POINTS The nucleus reuniens (Re), a nucleus of the midline thalamus, is part of a cognitive network including the hippocampus and the medial prefrontal cortex. To date, very few studies have examined the electrophysiological properties of Re neurons at a cellular level. The majority of Re neurons exhibit spontaneous action potential firing at rest. This is independent of classical amino-acid mediated synaptic transmission. When driven by various forms of depolarizing current stimulus, Re neurons display considerable diversity in their firing patterns. As a result of the presence of a low threshold Ca2+ channel, spike output functions are strongly modulated by the prestimulus membrane potential. Finally, we describe a novel form of activity-dependant intrinsic plasticity that eliminates the high-frequency burst firing present in many Re neurons. These results provide a comprehensive summary of the intrinsic electrophysiological properties of Re neurons allowing us to better consider the role of the Re in cognitive processes. ABSTRACT The nucleus reuniens (Re) is the largest of the midline thalamic nuclei. We have performed a detailed neurophysiological characterization of neurons in the rostral Re of brain slices prepared from adult male mice. At resting potential (-63.7 ± 0.6 mV), ∼90% of Re neurons fired action potentials, typically continuously at ∼8 Hz. Although Re neurons experience a significant spontaneous barrage of fast, amino-acid-mediate synaptic transmission, this was not predominantly responsible for spontaneous spiking because firing persisted in the presence of glutamate and GABA receptor antagonists. With resting potential preset to -80 mV, -20 pA current injections revealed a mean input resistance of 615 MΩ and a mean time constant of 38 ms. Following cessation of this stimulus, a significant rebound potential was seen that was sometimes sufficiently large to trigger a short burst of very high frequency (100-300 Hz) firing. In most cells, short (2 ms), strong (2 nA) current injections elicited a single spike followed by a large afterdepolarizing potential which, when suprathreshold, generated high-frequency spiking. Similarly, in the majority of cells preset at -80 mV, 500 ms depolarizing current injections to cells led to a brief initial burst of very high-frequency firing, although this was lost when cells were preset at -72 mV. Biophysical and pharmacological experiments indicate a prominent role for T-type Ca2+ channels in the high-frequency bursting of Re neurons. Finally, we describe a novel form of activity-dependent intrinsic plasticity that persistently eliminates the burst firing potential of Re neurons.
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Affiliation(s)
- Darren A. Walsh
- Institute of Biomedical and Clinical Sciences, University of Exeter Medical SchoolHatherly LaboratoryExeterUK
| | - Jonathan T. Brown
- Institute of Biomedical and Clinical Sciences, University of Exeter Medical SchoolHatherly LaboratoryExeterUK
| | - Andrew D. Randall
- Institute of Biomedical and Clinical Sciences, University of Exeter Medical SchoolHatherly LaboratoryExeterUK
- School of Clinical SciencesUniversity of BristolBristolUK
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10
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Expression of mutant DISC1 in Purkinje cells increases their spontaneous activity and impairs cognitive and social behaviors in mice. Neurobiol Dis 2017; 103:144-153. [PMID: 28392471 DOI: 10.1016/j.nbd.2017.04.008] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2016] [Revised: 04/02/2017] [Accepted: 04/05/2017] [Indexed: 12/15/2022] Open
Abstract
In addition to motor function, the cerebellum has been implicated in cognitive and social behaviors. Various structural and functional abnormalities of Purkinje cells (PCs) have been observed in schizophrenia and autism. As PCs express the gene Disrupted-In-Schizophrenia-1 (DISC1), and DISC1 variants have been associated with neurodevelopmental disorders, we evaluated the role of DISC1 in cerebellar physiology and associated behaviors using a mouse model of inducible and selective expression of a dominant-negative, C-terminus truncated human DISC1 (mutant DISC1) in PCs. Mutant DISC1 male mice demonstrated impaired social and novel placement recognition. No group differences were found in novelty-induced hyperactivity, elevated plus maze test, spontaneous alternation, spatial recognition in Y maze, sociability or accelerated rotarod. Expression of mutant DISC1 was associated with a decreased number of large somata PCs (volume: 3000-5000μm3) and an increased number of smaller somata PCs (volume: 750-1000μm3) without affecting the total number of PCs or the volume of the cerebellum. Compared to control mice, attached loose patch recordings of PCs in mutant DISC1 mice revealed increased spontaneous firing of PCs; and whole cell recordings showed increased amplitude and frequency of mEPSCs without significant changes in either Rinput or parallel fiber EPSC paired-pulse ratio. Our findings indicate that mutant DISC1 alters the physiology of PCs, possibly leading to abnormal recognition memory in mice.
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11
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Barker GRI, Banks PJ, Scott H, Ralph GS, Mitrophanous KA, Wong LF, Bashir ZI, Uney JB, Warburton EC. Separate elements of episodic memory subserved by distinct hippocampal–prefrontal connections. Nat Neurosci 2017; 20:242-250. [DOI: 10.1038/nn.4472] [Citation(s) in RCA: 78] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2016] [Accepted: 12/01/2016] [Indexed: 12/20/2022]
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12
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Murphy E, Benítez-Burraco A. Bridging the Gap between Genes and Language Deficits in Schizophrenia: An Oscillopathic Approach. Front Hum Neurosci 2016; 10:422. [PMID: 27601987 PMCID: PMC4993770 DOI: 10.3389/fnhum.2016.00422] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2016] [Accepted: 08/08/2016] [Indexed: 12/11/2022] Open
Abstract
Schizophrenia is characterized by marked language deficits, but it is not clear how these deficits arise from the alteration of genes related to the disease. The goal of this paper is to aid the bridging of the gap between genes and schizophrenia and, ultimately, give support to the view that the abnormal presentation of language in this condition is heavily rooted in the evolutionary processes that brought about modern language. To that end we will focus on how the schizophrenic brain processes language and, particularly, on its distinctive oscillatory profile during language processing. Additionally, we will show that candidate genes for schizophrenia are overrepresented among the set of genes that are believed to be important for the evolution of the human faculty of language. These genes crucially include (and are related to) genes involved in brain rhythmicity. We will claim that this translational effort and the links we uncover may help develop an understanding of language evolution, along with the etiology of schizophrenia, its clinical/linguistic profile, and its high prevalence among modern populations.
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Affiliation(s)
- Elliot Murphy
- Division of Psychology and Language Sciences, University College London London, UK
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13
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Murphy E, Benítez-Burraco A. Language deficits in schizophrenia and autism as related oscillatory connectomopathies: An evolutionary account. Neurosci Biobehav Rev 2016; 83:742-764. [PMID: 27475632 DOI: 10.1016/j.neubiorev.2016.07.029] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2016] [Revised: 06/23/2016] [Accepted: 07/25/2016] [Indexed: 01/28/2023]
Abstract
Schizophrenia (SZ) and autism spectrum disorders (ASD) are characterised by marked language deficits, but it is not clear how these arise from gene mutations associated with the disorders. Our goal is to narrow the gap between SZ and ASD and, ultimately, give support to the view that they represent abnormal (but related) ontogenetic itineraries for the human faculty of language. We will focus on the distinctive oscillatory profiles of the SZ and ASD brains, in turn using these insights to refine our understanding of how the brain implements linguistic computations by exploring a novel model of linguistic feature-set composition. We will argue that brain rhythms constitute the best route to interpreting language deficits in both conditions and mapping them to neural dysfunction and risk alleles of the genes. Importantly, candidate genes for SZ and ASD are overrepresented among the gene sets believed to be important for language evolution. This translational effort may help develop an understanding of the aetiology of SZ and ASD and their high prevalence among modern populations.
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Affiliation(s)
- Elliot Murphy
- Division of Psychology and Language Sciences, University College London, London, United Kingdom.
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Devine MJ, Norkett R, Kittler JT. DISC1 is a coordinator of intracellular trafficking to shape neuronal development and connectivity. J Physiol 2016; 594:5459-69. [PMID: 27121900 DOI: 10.1113/jp272187] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2016] [Accepted: 03/31/2016] [Indexed: 01/14/2023] Open
Abstract
The long, asymmetric and specialised architecture of neuronal processes necessitates a properly regulated transport network of molecular motors and cytoskeletal tracks. This allows appropriate distribution of cargo for correct formation and activity of the synapse, and thus normal neuronal communication. This communication is impaired in psychiatric disease, and ongoing studies have proposed that Disrupted in schizophrenia 1 (DISC1) is an important genetic risk factor for these disorders. The mechanisms by which DISC1 dysfunction might increase propensity to psychiatric disease are not completely understood; however, an emerging theme is that DISC1 can function as a key regulator of neuronal intracellular trafficking. Transport of a wide range of potential cargoes - including mRNAs, neurotransmitter receptors, vesicles and mitochondria - can be modulated by DISC1, and therefore is susceptible to DISC1 dysfunction. This theme highlights the importance of understanding precisely how DISC1 can regulate intracellular trafficking, and suggests that a novel approach to the treatment of psychiatric disorders could be provided by targeting this protein and the trafficking machinery with which it interacts.
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Affiliation(s)
- M J Devine
- Department of Neuroscience, Physiology and Pharmacology, University College London, Gower Street, London, UK
| | - R Norkett
- Department of Neuroscience, Physiology and Pharmacology, University College London, Gower Street, London, UK
| | - J T Kittler
- Department of Neuroscience, Physiology and Pharmacology, University College London, Gower Street, London, UK.
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Neuroimaging findings from childhood onset schizophrenia patients and their non-psychotic siblings. Schizophr Res 2016; 173:124-131. [PMID: 25819937 PMCID: PMC4583796 DOI: 10.1016/j.schres.2015.03.003] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/30/2014] [Revised: 02/26/2015] [Accepted: 03/02/2015] [Indexed: 12/14/2022]
Abstract
Childhood onset schizophrenia (COS), with onset of psychosis before age 13, is a rare form of schizophrenia that represents a more severe and chronic form of the adult onset illness. In this review we examine structural and functional magnetic resonance imaging (MRI) studies of COS and non-psychotic siblings of COS patients in the context of studies of schizophrenia as a whole. Studies of COS to date reveal progressive loss of gray matter volume and cortical thinning, ventricular enlargement, progressive decline in cerebellar volume and a significant but fixed deficit in hippocampal volume. COS is also associated with a slower rate of white matter growth and disrupted local connectivity strength. Sibling studies indicate that non-psychotic siblings of COS patients share many of these brain abnormalities, including decreased cortical thickness and disrupted white matter growth, yet these abnormalities normalize with age. Cross-sectional and longitudinal neuroimaging studies remain some of the few methods for assessing human brain function and play a pivotal role in the quest for understanding the neurobiology of schizophrenia as well as other psychiatric disorders. Parallel studies in non-psychotic siblings provide a unique opportunity to understand both risk and resilience in schizophrenia.
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Altered Intrinsic Pyramidal Neuron Properties and Pathway-Specific Synaptic Dysfunction Underlie Aberrant Hippocampal Network Function in a Mouse Model of Tauopathy. J Neurosci 2016; 36:350-63. [PMID: 26758828 DOI: 10.1523/jneurosci.2151-15.2016] [Citation(s) in RCA: 61] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
UNLABELLED The formation and deposition of tau protein aggregates is proposed to contribute to cognitive impairments in dementia by disrupting neuronal function in brain regions, including the hippocampus. We used a battery of in vivo and in vitro electrophysiological recordings in the rTg4510 transgenic mouse model, which overexpresses a mutant form of human tau protein, to investigate the effects of tau pathology on hippocampal neuronal function in area CA1 of 7- to 8-month-old mice, an age point at which rTg4510 animals exhibit advanced tau pathology and progressive neurodegeneration. In vitro recordings revealed shifted theta-frequency resonance properties of CA1 pyramidal neurons, deficits in synaptic transmission at Schaffer collateral synapses, and blunted plasticity and imbalanced inhibition at temporoammonic synapses. These changes were associated with aberrant CA1 network oscillations, pyramidal neuron bursting, and spatial information coding in vivo. Our findings relate tauopathy-associated changes in cellular neurophysiology to altered behavior-dependent network function. SIGNIFICANCE STATEMENT Dementia is characterized by the loss of learning and memory ability. The deposition of tau protein aggregates in the brain is a pathological hallmark of dementia; and the hippocampus, a brain structure known to be critical in processing learning and memory, is one of the first and most heavily affected regions. Our results show that, in area CA1 of hippocampus, a region involved in spatial learning and memory, tau pathology is associated with specific disturbances in synaptic, cellular, and network-level function, culminating in the aberrant encoding of spatial information and spatial memory impairment. These studies identify several novel ways in which hippocampal information processing may be disrupted in dementia, which may provide targets for future therapeutic intervention.
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Tomoda T, Sumitomo A, Jaaro-Peled H, Sawa A. Utility and validity of DISC1 mouse models in biological psychiatry. Neuroscience 2016; 321:99-107. [PMID: 26768401 PMCID: PMC4803604 DOI: 10.1016/j.neuroscience.2015.12.061] [Citation(s) in RCA: 56] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2015] [Revised: 12/31/2015] [Accepted: 12/31/2015] [Indexed: 11/26/2022]
Abstract
We have seen an era of explosive progress in translating neurobiology into etiological understanding of mental disorders for the past 10-15 years. The discovery of Disrupted-in-schizophrenia 1 (DISC1) gene was one of the major driving forces that have contributed to the progress. The finding that DISC1 plays crucial roles in neurodevelopment and synapse regulation clearly underscored the utility and validity of DISC1-related biology in advancing our understanding of pathophysiological processes underlying psychiatric conditions. Despite recent genetic studies that failed to identify DISC1 as a risk gene for sporadic cases of schizophrenia, DISC1 mutant mice, coupled with various environmental stressors, have proven successful in satisfying face validity as models of a wide range of human psychiatric conditions. Investigating mental disorders using these models is expected to further contribute to the circuit-level understanding of the pathological mechanisms, as well as to the development of novel therapeutic strategies in the future.
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Affiliation(s)
- T Tomoda
- Medical Innovation Center, Kyoto University Graduate School of Medicine, Kyoto 606-8507, Japan.
| | - A Sumitomo
- Medical Innovation Center, Kyoto University Graduate School of Medicine, Kyoto 606-8507, Japan
| | - H Jaaro-Peled
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA
| | - A Sawa
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA.
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18
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Sigurdsson T. Neural circuit dysfunction in schizophrenia: Insights from animal models. Neuroscience 2016; 321:42-65. [DOI: 10.1016/j.neuroscience.2015.06.059] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2015] [Revised: 06/15/2015] [Accepted: 06/26/2015] [Indexed: 12/17/2022]
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Disrupted in schizophrenia 1 (DISC1) L100P mutants have impaired activity-dependent plasticity in vivo and in vitro. Transl Psychiatry 2016; 6:e712. [PMID: 26756905 PMCID: PMC5068880 DOI: 10.1038/tp.2015.206] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/23/2015] [Accepted: 10/30/2015] [Indexed: 12/26/2022] Open
Abstract
Major neuropsychiatric disorders are genetically complex but share overlapping etiology. Mice mutant for rare, highly penetrant risk variants can be useful in dissecting the molecular mechanisms involved. The gene disrupted in schizophrenia 1 (DISC1) has been associated with increased risk for neuropsychiatric conditions. Mice mutant for Disc1 display morphological, functional and behavioral deficits that are consistent with impairments observed across these disorders. Here we report that Disc1 L100P mutants are less able to reorganize cortical circuitry in response to stimulation in vivo. Molecular analysis reveals that the mutants have a reduced expression of PSD95 and pCREB in visual cortex and fail to adjust expression of such markers in response to altered stimulation. In vitro analysis shows that mutants have impaired functional reorganization of cortical neurons in response to selected forms of neuronal stimulation, but there is no altered basal expression of synaptic markers. These findings suggest that DISC1 has a critical role in the reorganization of cortical plasticity and that this phenotype becomes evident only under challenge, even at early postnatal stages. This result may represent an important etiological mechanism in the emergence of neuropsychiatric disorders.
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Rosen AM, Spellman T, Gordon JA. Electrophysiological endophenotypes in rodent models of schizophrenia and psychosis. Biol Psychiatry 2015; 77:1041-9. [PMID: 25910423 PMCID: PMC4444383 DOI: 10.1016/j.biopsych.2015.03.021] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/12/2014] [Revised: 03/03/2015] [Accepted: 03/23/2015] [Indexed: 02/06/2023]
Abstract
Schizophrenia is caused by a diverse array of risk factors and results in a similarly diverse set of symptoms. Electrophysiological endophenotypes lie between risks and symptoms and have the potential to link the two. Electrophysiological studies in rodent models, described here, demonstrate that widely differing risk factors result in a similar set of core electrophysiological endophenotypes, suggesting the possibility of a shared neurobiological substrate.
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Affiliation(s)
- Andrew M. Rosen
- Department of Psychiatry, College of Physicians and Surgeons Columbia University New York, NY 10032
| | - Timothy Spellman
- Department of Physiology, College of Physicians and Surgeons Columbia University New York, NY 10032
| | - Joshua A. Gordon
- Department of Psychiatry, College of Physicians and Surgeons Columbia University New York, NY 10032,Division of Integrative Neuroscience New York State Psychiatric Institute New York NY 10032,Correspondence to: Joshua A. Gordon 1051 Riverside Drive Unit 87 Kolb Annex Room 140 New York, NY 10032 Ph. 646 774-7116 Fax. 646 774-7101
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Affiliation(s)
- Scott Thompson
- Department of Physiology, University of Maryland School of Medicine, Baltimore, MD, USA.
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Randall AD, Kurihara M, Brandon NJ, Brown JT. Disrupted in schizophrenia 1 and synaptic function in the mammalian central nervous system. Eur J Neurosci 2014; 39:1068-73. [PMID: 24712987 PMCID: PMC4232872 DOI: 10.1111/ejn.12500] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2013] [Revised: 01/02/2014] [Accepted: 01/07/2014] [Indexed: 11/28/2022]
Abstract
The disrupted in schizophrenia 1 (DISC1) gene is found at the breakpoint of an inherited chromosomal translocation, and segregates with major mental illnesses. Its potential role in central nervous system (CNS) malfunction has triggered intensive investigation of the biological roles played by DISC1, with the hope that this may shed new light on the pathobiology of psychiatric disease. Such work has ranged from investigations of animal behavior to detailed molecular-level analysis of the assemblies that DISC1 forms with other proteins. Here, we discuss the evidence for a role of DISC1 in synaptic function in the mammalian CNS.
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Affiliation(s)
- Andrew D Randall
- School of Physiology and Pharmacology, School of Medical Sciences, University of Bristol, Bristol, UK; Institute of Biomedical and Clinical Sciences, University of Exeter, The Hatherley Building, Prince of Wales Road, Exeter, EX4 4PS, UK
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