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Greenfield SA, Ferrati G, Coen CW, Vadisiute A, Molnár Z, Garcia-Rates S, Frautschy S, Cole GM. Characterization of a Bioactive Peptide T14 in the Human and Rodent Substantia Nigra: Implications for Neurodegenerative Disease. Int J Mol Sci 2022; 23:ijms232113119. [PMID: 36361905 PMCID: PMC9654939 DOI: 10.3390/ijms232113119] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2022] [Revised: 10/20/2022] [Accepted: 10/26/2022] [Indexed: 11/25/2022] Open
Abstract
The substantia nigra is generally considered to show significant cell loss not only in Parkinson's but also in Alzheimer's disease, conditions that share several neuropathological traits. An interesting feature of this nucleus is that the pars compacta dopaminergic neurons contain acetylcholinesterase (AChE). Independent of its enzymatic role, this protein is released from pars reticulata dendrites, with effects that have been observed in vitro, ex vivo and in vivo. The part of the molecule responsible for these actions has been identified as a 14-mer peptide, T14, cleaved from the AChE C-terminus and acting at an allosteric site on alpha-7 nicotinic receptors, with consequences implicated in neurodegeneration. Here, we show that free T14 is co-localized with tyrosine hydroxylase in rodent pars compacta neurons. In brains with Alzheimer's pathology, the T14 immunoreactivity in these neurons increases in density as their number decreases with the progression of the disease. To explore the functional implications of raised T14 levels in the substantia nigra, the effect of exogenous peptide on electrically evoked neuronal activation was tested in rat brain slices using optical imaging with a voltage-sensitive dye (Di-4-ANEPPS). A significant reduction in the activation response was observed; this was blocked by the cyclized variant of T14, NBP14. In contrast, no such effect of the peptide was seen in the striatum, a region lacking the T14 target, alpha-7 receptors. These findings add to the accumulating evidence that T14 is a key signaling molecule in neurodegenerative disorders and that its antagonist NBP14 has therapeutic potential.
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Affiliation(s)
- Susan Adele Greenfield
- Neuro-Bio Ltd., Building F5, Culham Science Centre, Abingdon OX14 3DB, UK
- Correspondence:
| | - Giovanni Ferrati
- Neuro-Bio Ltd., Building F5, Culham Science Centre, Abingdon OX14 3DB, UK
| | - Clive W. Coen
- Faculty of Life Sciences & Medicine, King’s College London, London SE1 1UL, UK
| | - Auguste Vadisiute
- Department Physiology, Anatomy and Genetics, University of Oxford, Sherrington Building, Parks Road, Oxford OX1 3PT, UK
| | - Zoltan Molnár
- Department Physiology, Anatomy and Genetics, University of Oxford, Sherrington Building, Parks Road, Oxford OX1 3PT, UK
| | - Sara Garcia-Rates
- Neuro-Bio Ltd., Building F5, Culham Science Centre, Abingdon OX14 3DB, UK
| | - Sally Frautschy
- Department of Neurology & Medicine, David Geffen School of Medicine at UCLA and Veterans Affairs Healthcare System, Los Angeles, CA 90095, USA
| | - Gregory M. Cole
- Department of Neurology & Medicine, David Geffen School of Medicine at UCLA and Veterans Affairs Healthcare System, Los Angeles, CA 90095, USA
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Neuronal genetic rescue normalizes brain network dynamics in a lysosomal storage disorder despite persistent storage accumulation. Mol Ther 2022; 30:2464-2473. [PMID: 35395398 PMCID: PMC9263320 DOI: 10.1016/j.ymthe.2022.03.025] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2021] [Revised: 02/23/2022] [Accepted: 03/31/2022] [Indexed: 11/22/2022] Open
Abstract
Although neurologic symptoms occur in two-thirds of lysosomal storage disorders (LSDs), for most we do not understand the mechanisms underlying brain dysfunction. A major unanswered question is if the pathogenic hallmark of LSDs, storage accumulation, induces functional defects directly or is a disease bystander. Also, for most LSDs we do not know the impact of loss-of-function in individual cell types. Understanding these critical questions are essential to therapy development. Here, we determined the impact of genetic rescue in distinct cell types on neural circuit dysfunction in CLN3 disease, the most common pediatric dementia and a paradigmatic neurodegenerative LSD. We restored Cln3 expression via AAV-mediated gene delivery and conditional genetic rescue in a CLN3 disease mouse model. Surprisingly, we found that low-level rescue of Cln3 expression in neurons alone normalized clinically-relevant electrophysiologic markers of network dysfunction, despite the presence of substantial residual histopathology, in contrast to restoring expression in astrocytes. Thus, loss of CLN3 function in neurons, not storage accumulation, underlies neurologic dysfunction in CLN3 disease, implying that storage clearance may be an inappropriate target for therapy development and an ineffectual biomarker.
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A computational framework for optimal control of a self-adjustive neural system with activity-dependent and homeostatic plasticity. Neuroimage 2021; 230:117805. [PMID: 33524581 DOI: 10.1016/j.neuroimage.2021.117805] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2020] [Revised: 01/20/2021] [Accepted: 01/24/2021] [Indexed: 12/13/2022] Open
Abstract
The control of the brain system has received increasing attention in the domain of brain science. Most brain control studies have been conducted to explore the brain network's graph-theoretic properties or to produce the desired state based on neural state dynamics, regarding the brain as a passively responding system. However, the self-adjusting nature of neural system after treatment has not been fully considered in the brain control. In the present study, we propose a computational framework for optimal control of the brain with a self-adjustment process in the effective connectivity after treatment. The neural system is modeled to adjust its outgoing effective connectivity as activity-dependent plasticity after treatment, followed by synaptic rescaling of incoming effective connectivity. To control this neural system to induce the desired function, the system's self-adjustment parameter is first estimated, based on which the treatment is optimized. Utilizing this framework, we conducted simulations of optimal control over a functional hippocampal circuitry, estimated using dynamic causal modeling of voltage-sensitive dye imaging from the wild type and mutant mice, responding to consecutive electrical stimuli. Simulation results for optimal control of the abnormal circuit toward a healthy circuit using a single node treatment, neural-type specific treatment as an analogy of medication, and combined treatments of medication and nodal treatment suggest the plausibility of the current framework in controlling the self-adjusting neural system within a restricted treatment setting. We believe the proposed computational framework of the self-adjustment system would help optimal control of the dynamic brain after treatment.
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Kang J, Jung K, Eo J, Son J, Park HJ. Dynamic causal modeling of hippocampal activity measured via mesoscopic voltage-sensitive dye imaging. Neuroimage 2020; 213:116755. [DOI: 10.1016/j.neuroimage.2020.116755] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2019] [Revised: 03/10/2020] [Accepted: 03/14/2020] [Indexed: 10/24/2022] Open
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Ahrens-Nicklas RC, Tecedor L, Hall AF, Lysenko E, Cohen AS, Davidson BL, Marsh ED. Neuronal network dysfunction precedes storage and neurodegeneration in a lysosomal storage disorder. JCI Insight 2019; 4:131961. [PMID: 31573978 PMCID: PMC6948765 DOI: 10.1172/jci.insight.131961] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2019] [Accepted: 09/25/2019] [Indexed: 12/29/2022] Open
Abstract
Accumulation of lysosomal storage material and late-stage neurodegeneration are hallmarks of lysosomal storage disorders (LSDs) affecting the brain. Yet, for most LSDs, including CLN3 disease, the most common form of childhood dementia, it is unclear what mechanisms drive neurologic symptoms. Do deficits arise from loss of function of the mutated protein or toxicity from storage accumulation? Here, using in vitro voltage-sensitive dye imaging and in vivo electrophysiology, we find progressive hippocampal dysfunction occurs before notable lysosomal storage and neuronal loss in 2 CLN3 disease mouse models. Pharmacologic reversal of lysosomal storage deposition in young mice does not rescue this circuit dysfunction. Additionally, we find that CLN3 disease mice lose an electrophysiologic marker of new memory encoding - hippocampal sharp-wave ripples. This discovery, which is also seen in Alzheimer's disease, suggests the possibility of a shared electrophysiologic signature of dementia. Overall, our data describe new insights into previously unknown network-level changes occurring in LSDs affecting the central nervous system and highlight the need for new therapeutic interventions targeting early circuit defects.
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Affiliation(s)
| | | | - Arron F. Hall
- Division of Human Genetics, Department of Pediatrics
| | | | | | | | - Eric D. Marsh
- Division of Child Neurology, Department of Neurology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
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6
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Ferrati G, Bion G, Harris AJ, Greenfield S. Protective and reversal actions of a novel peptidomimetic against a pivotal toxin implicated in Alzheimer's disease. Biomed Pharmacother 2018; 109:1052-1061. [PMID: 30551355 DOI: 10.1016/j.biopha.2018.10.124] [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: 07/05/2018] [Revised: 10/19/2018] [Accepted: 10/21/2018] [Indexed: 11/26/2022] Open
Abstract
Despite the many attempts to understand the aetiology of Alzheimer's disease, the basic mechanisms accounting for the progressive cycle of neuronal loss are still unknown. Previous work has suggested that the pivotal molecule mediating neurodegeneration could be an independently acting peptide cleaved from acetylcholinesterase. This previously unidentified agent acts as a signalling molecule in selectively vulnerable groups of cells where erstwhile developmental mechanisms are activated inappropriately to have a toxic effect in the context of the mature brain. We have previously shown that the toxic actions of this peptide, whose level is doubled in the Alzheimer brain, can be blocked by a cyclised variant (NBP14). However, the size and properties of NBP14 would render it unlikely as a feasible therapeutic candidate. Here therefore we test a synthetic peptidomimetic (NB-0193), modelled on the binding of NBP14 to the target alpha-7 nicotinic receptor, and benchmarked against it to screen for reversal effects using real-time optical imaging in rat brain slices. The blocking action of NB-0193 was confirmed by testing its effect against peptide-induced calcium influx in cell cultures, where it showed a dose-dependent profile over a trophic-toxic range. Moreover, NB-0193 presented promising pharmacokinetic characteristics and could therefore prompt a new therapeutic approach against Alzheimer's disease.
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Affiliation(s)
- Giovanni Ferrati
- Neuro-Bio Ltd, Culham Science Centre, Building F5, Abingdon, OX14 3DB, UK.
| | - Georgi Bion
- Neuro-Bio Ltd, Culham Science Centre, Building F5, Abingdon, OX14 3DB, UK
| | - Andrew J Harris
- Pharmidex, European Knowledge Centre, Hatfield, Hertfordshire, AL10 9SN, UK
| | - Susan Greenfield
- Neuro-Bio Ltd, Culham Science Centre, Building F5, Abingdon, OX14 3DB, UK
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A Multidisciplinary Approach Reveals an Age-Dependent Expression of a Novel Bioactive Peptide, Already Involved in Neurodegeneration, in the Postnatal Rat Forebrain. Brain Sci 2018; 8:brainsci8070132. [PMID: 29996490 PMCID: PMC6070872 DOI: 10.3390/brainsci8070132] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2018] [Revised: 07/04/2018] [Accepted: 07/06/2018] [Indexed: 11/16/2022] Open
Abstract
The basal forebrain has received much attention due to its involvement in multiple cognitive functions, but little is known about the basic neuronal mechanisms underlying its development, nor those mediating its primary role in Alzheimer’s disease. We have previously suggested that a novel 14-mer peptide, ‘T14’, could play a pivotal role in Alzheimer’s disease, via reactivation of a developmental signaling pathway. In this study, we have characterized T14 in the context of post-natal rat brain development, using a combination of different techniques. Ex-vivo rat brain slices containing the basal forebrain, at different stages of development, were used to investigate large-scale neuronal network activity in real time with voltage-sensitive dye imaging. Subsequent Western blot analysis revealed the expression profile of endogenous T14, its target alpha7 nicotinic receptor and the familiar markers of Alzheimer’s: amyloid beta and phosphorylated Tau. Results indicated maximal neuronal activity at the earliest ages during development, reflected in a concomitant profile of T14 peptide levels and related proteins. In conclusion, these findings show that the peptide, already implicated in neurodegenerative events, has an age-dependent expression, suggesting a possible contribution to the physiological mechanisms underlying brain maturation.
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8
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Folweiler KA, Samuel S, Metheny HE, Cohen AS. Diminished Dentate Gyrus Filtering of Cortical Input Leads to Enhanced Area Ca3 Excitability after Mild Traumatic Brain Injury. J Neurotrauma 2018; 35:1304-1317. [PMID: 29338620 PMCID: PMC5962932 DOI: 10.1089/neu.2017.5350] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Mild traumatic brain injury (mTBI) disrupts hippocampal function and can lead to long-lasting episodic memory impairments. The encoding of episodic memories relies on spatial information processing within the hippocampus. As the primary entry point for spatial information into the hippocampus, the dentate gyrus is thought to function as a physiological gate, or filter, of afferent excitation before reaching downstream area Cornu Ammonis (CA3). Although injury has previously been shown to alter dentate gyrus network excitability, it is unknown whether mTBI affects dentate gyrus output to area CA3. In this study, we assessed hippocampal function, specifically the interaction between the dentate gyrus and CA3, using behavioral and electrophysiological techniques in ex vivo brain slices 1 week following mild lateral fluid percussion injury (LFPI). Behaviorally, LFPI mice were found to be impaired in an object-place recognition task, indicating that spatial information processing in the hippocampus is disrupted. Extracellular recordings and voltage-sensitive dye imaging demonstrated that perforant path activation leads to the aberrant spread of excitation from the dentate gyrus into area CA3 along the mossy fiber pathway. These results suggest that after mTBI, the dentate gyrus has a diminished capacity to regulate cortical input into the hippocampus, leading to increased CA3 network excitability. The loss of the dentate filtering efficacy reveals a potential mechanism by which hippocampal-dependent spatial information processing is disrupted, and may contribute to memory dysfunction after mTBI.
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Affiliation(s)
- Kaitlin A. Folweiler
- Department of Anesthesiology and Critical Care Medicine, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania
- Department of Anesthesiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
- Neuroscience Graduate Group, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Sandy Samuel
- Department of Anesthesiology and Critical Care Medicine, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania
- Department of Anesthesiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Hannah E. Metheny
- Department of Anesthesiology and Critical Care Medicine, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania
- Department of Anesthesiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Akiva S. Cohen
- Department of Anesthesiology and Critical Care Medicine, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania
- Department of Anesthesiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
- Neuroscience Graduate Group, University of Pennsylvania, Philadelphia, Pennsylvania
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9
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Greenfield SA, Badin AS, Ferrati G, Devonshire IM. Optical imaging of the rat brain suggests a previously missing link between top-down and bottom-up nervous system function. NEUROPHOTONICS 2017; 4:031213. [PMID: 28573153 PMCID: PMC5443969 DOI: 10.1117/1.nph.4.3.031213] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/12/2017] [Accepted: 04/26/2017] [Indexed: 06/07/2023]
Abstract
Optical imaging with voltage-sensitive dyes enables the visualization of extensive yet highly transient coalitions of neurons (assemblies) operating throughout the brain on a subsecond time scale. We suggest that operating at the mesoscale level of brain organization, neuronal assemblies may provide a functional link between "bottom-up" cellular mechanisms and "top-down" cognitive ones within anatomically defined regions. We demonstrate in ex vivo rat brain slices how varying spatiotemporal dynamics of assemblies reveal differences not previously appreciated between: different stages of development in cortical versus subcortical brain areas, different sensory modalities (hearing versus vision), different classes of psychoactive drugs (anesthetics versus analgesics), different effects of anesthesia linked to hyperbaric conditions and, in vivo, depths of anesthesia. The strategy of voltage-sensitive dye imaging is therefore as powerful as it is versatile and as such can now be applied to the evaluation of neurochemical signaling systems and the screening of related new drugs, as well as to mathematical modeling and, eventually, even theories of consciousness.
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Affiliation(s)
- Susan A. Greenfield
- Neuro-Bio Ltd., Building F5, Culham Science Centre, Abingdon, United Kingdom
| | - Antoine-Scott Badin
- Neuro-Bio Ltd., Building F5, Culham Science Centre, Abingdon, United Kingdom
- University of Oxford, Department of Physiology, Anatomy & Genetics, Oxford, United Kingdom
| | - Giovanni Ferrati
- Neuro-Bio Ltd., Building F5, Culham Science Centre, Abingdon, United Kingdom
| | - Ian M. Devonshire
- Nottingham University Medical School, Queen’s Medical Centre, Nottingham, United Kingdom
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10
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Badin AS, Fermani F, Greenfield SA. The Features and Functions of Neuronal Assemblies: Possible Dependency on Mechanisms beyond Synaptic Transmission. Front Neural Circuits 2017; 10:114. [PMID: 28119576 PMCID: PMC5223595 DOI: 10.3389/fncir.2016.00114] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2016] [Accepted: 12/22/2016] [Indexed: 11/13/2022] Open
Abstract
"Neuronal assemblies" are defined here as coalitions within the brain of millions of neurons extending in space up to 1-2 mm, and lasting for hundreds of milliseconds: as such they could potentially link bottom-up, micro-scale with top-down, macro-scale events. The perspective first compares the features in vitro versus in vivo of this underappreciated "meso-scale" level of brain processing, secondly considers the various diverse functions in which assemblies may play a pivotal part, and thirdly analyses whether the surprisingly spatially extensive and prolonged temporal properties of assemblies can be described exclusively in terms of classic synaptic transmission or whether additional, different types of signaling systems are likely to operate. Based on our own voltage-sensitive dye imaging (VSDI) data acquired in vitro we show how restriction to only one signaling process, i.e., synaptic transmission, is unlikely to be adequate for modeling the full profile of assemblies. Based on observations from VSDI with its protracted spatio-temporal scales, we suggest that two other, distinct processes are likely to play a significant role in assembly dynamics: "volume" transmission (the passive diffusion of diverse bioactive transmitters, hormones, and modulators), as well as electrotonic spread via gap junctions. We hypothesize that a combination of all three processes has the greatest potential for deriving a realistic model of assemblies and hence elucidating the various complex brain functions that they may mediate.
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Affiliation(s)
- Antoine-Scott Badin
- Neuro-Bio Ltd., Culham Science CentreAbingdon, UK; Department of Physiology, Anatomy and Genetics, Mann Group, University of OxfordOxford, UK
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11
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Palmer CP, Metheny HE, Elkind JA, Cohen AS. Diminished amygdala activation and behavioral threat response following traumatic brain injury. Exp Neurol 2016; 277:215-226. [PMID: 26791254 PMCID: PMC4761321 DOI: 10.1016/j.expneurol.2016.01.004] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2015] [Revised: 12/28/2015] [Accepted: 01/05/2016] [Indexed: 11/30/2022]
Abstract
Each year, approximately 3.8 million people suffer mild to moderate traumatic brain injuries (mTBI) that result in an array of neuropsychological symptoms and disorders. Despite these alarming statistics, the neurological bases of these persistent, debilitating neuropsychological symptoms are currently poorly understood. In this study we examined the effects of mTBI on the amygdala, a brain structure known to be critically involved in the processing of emotional stimuli. Seven days after lateral fluid percussion injury (LFPI), mice underwent a series of physiological and behavioral experiments to assess amygdala function. Brain-injured mice exhibited a decreased threat response in a cued fear conditioning paradigm, congruent with a decrease in amygdala excitability determined with basolateral amygdala (BLA) field excitatory post-synaptic potentials together with voltage-sensitive dye imaging (VSD). Furthermore, beyond exposing a general decrease in the excitability of the primary input of the amygdala, the lateral amygdala (LA), VSD also revealed a decrease in the relative strength or activation of internuclear amygdala circuit projections after LFPI. Thus, not only does activation of the LA require increased stimulation, but the proportion of this activation that is propagated to the primary output of the amygdala, the central amygdala, is also diminished following LFPI. Intracellular recordings revealed no changes in the intrinsic properties of BLA pyramidal neurons after LFPI. This data suggests that mild to moderate TBI has prominent effects on amygdala function and provides a potential neurological substrate for many of the neuropsychological symptoms suffered by TBI patients.
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Affiliation(s)
- Christopher P Palmer
- Neuroscience Graduate Group, Perelman School of Medicine, University of Pennsylvania, 3451 Walnut Street, Philadelphia, PA 19104, United States
| | - Hannah E Metheny
- Critical Care Medicine, Department of Anesthesiology, The Children's Hospital of Philadelphia, 3401 Civic Center Blvd, Philadelphia, PA 19104, United States
| | - Jaclynn A Elkind
- Critical Care Medicine, Department of Anesthesiology, The Children's Hospital of Philadelphia, 3401 Civic Center Blvd, Philadelphia, PA 19104, United States
| | - Akiva S Cohen
- Critical Care Medicine, Department of Anesthesiology, The Children's Hospital of Philadelphia, 3401 Civic Center Blvd, Philadelphia, PA 19104, United States; Department of Anesthesiology & Critical Care Medicine, Perelman School of Medicine, University of Pennsylvania, 3451 Walnut Street, Philadelphia, PA 19104, United States.
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12
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Badin AS, Morrill P, Devonshire IM, Greenfield SA. (II) Physiological profiling of an endogenous peptide in the basal forebrain: Age-related bioactivity and blockade with a novel modulator. Neuropharmacology 2016; 105:47-60. [PMID: 26773199 DOI: 10.1016/j.neuropharm.2016.01.012] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2015] [Accepted: 01/06/2016] [Indexed: 01/15/2023]
Abstract
Previous studies have suggested that neurodegeneration is an aberrant form of development, mediated by a novel peptide from the C-terminus of acetylcholinesterase (AChE). Using voltage-sensitive dye imaging we have investigated the effects of a synthetic version of this peptide in the in vitro rat basal forebrain, a key site of degeneration in Alzheimer's disease. The brain slice preparation enables direct visualisation in real-time of sub-second meso-scale neuronal coalitions ('Neuronal Assemblies') that serve as a powerful index of brain functional activity. Here we show that (1) assemblies are site-specific in their activity profile with the cortex displaying a significantly more extensive network activity than the sub-cortical basal forebrain; (2) there is an age-dependency, in both cortical and sub-cortical sites, with the younger brain (p14 rats) exhibiting more conspicuous assemblies over space and time compared to their older counterparts (p35-40 rats). (3) AChE-derived peptide significantly modulates the dynamics of neuronal assemblies in the basal forebrain of the p14 rat with the degree of modulation negatively correlated with age, (4) the differential in assembly size with age parallels the level of endogenous peptide in the brain, which also declines with maturity, and (5) this effect is completely reversed by a cyclised variant of AChE-peptide, 'NBP14'. These observations are attributed to an enhanced calcium entry that, according to developmental stage, could be either trophic or toxic, and as such may provide insight into the basic neurodegenerative process as well as an eventual therapeutic intervention.
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Affiliation(s)
- Antoine-Scott Badin
- Neuro-Bio Ltd, Building F5, Culham Science Centre, Oxfordshire, OX14 3DB, United Kingdom.
| | - Paul Morrill
- Neuro-Bio Ltd, Building F5, Culham Science Centre, Oxfordshire, OX14 3DB, United Kingdom
| | - Ian M Devonshire
- Neuro-Bio Ltd, Building F5, Culham Science Centre, Oxfordshire, OX14 3DB, United Kingdom
| | - Susan A Greenfield
- Neuro-Bio Ltd, Building F5, Culham Science Centre, Oxfordshire, OX14 3DB, United Kingdom
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13
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Knöpfel T, Gallero-Salas Y, Song C. Genetically encoded voltage indicators for large scale cortical imaging come of age. Curr Opin Chem Biol 2015; 27:75-83. [PMID: 26115448 DOI: 10.1016/j.cbpa.2015.06.006] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2015] [Revised: 05/22/2015] [Accepted: 06/05/2015] [Indexed: 11/19/2022]
Abstract
Electrical signals are fundamental to cellular sensing, communication and motility. In the nervous system, information is represented as receptor, synaptic and action potentials. Understanding how brain functions emerge from these electrical signals is one of the ultimate challenges in neuroscience and requires a methodology to monitor membrane voltage transients from large numbers of cells at high spatio-temporal resolution. Optical voltage imaging holds longstanding promises to achieve this, and has gained a fresh powerful momentum with the development of genetically encoded voltage indicators (GEVIs). With a focus on neuroimaging studies on intact mouse brains, we highlight recent advances in this field.
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Affiliation(s)
- Thomas Knöpfel
- Department of Medicine, Imperial College London, London W12 0NN, United Kingdom.
| | - Yasir Gallero-Salas
- Department of Medicine, Imperial College London, London W12 0NN, United Kingdom
| | - Chenchen Song
- Department of Medicine, Imperial College London, London W12 0NN, United Kingdom
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