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Pathway-specific TNF-mediated metaplasticity in hippocampal area CA1. Sci Rep 2022; 12:1746. [PMID: 35110639 PMCID: PMC8810872 DOI: 10.1038/s41598-022-05844-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2021] [Accepted: 01/19/2022] [Indexed: 01/29/2023] Open
Abstract
Long-term potentiation (LTP) is regulated in part by metaplasticity, the activity-dependent alterations in neural state that coordinate the direction, amplitude, and persistence of future synaptic plasticity. Previously, we documented a heterodendritic metaplasticity effect whereby high-frequency priming stimulation in stratum oriens (SO) of hippocampal CA1 suppressed subsequent LTP in the stratum radiatum (SR). The cytokine tumor necrosis factor (TNF) mediated this heterodendritic metaplasticity in wild-type rodents and in a mouse model of Alzheimer’s disease. Here, we investigated whether LTP at other afferent synapses to CA1 pyramidal cells were similarly affected by priming stimulation. We found that priming stimulation in SO inhibited LTP only in SR and not in a second independent pathway in SO, nor in stratum lacunosum moleculare (SLM). Synapses in SR were also more sensitive than SO or SLM to the LTP-inhibiting effects of pharmacological TNF priming. Neither form of priming was sex-specific, while the metaplasticity effects were absent in TNFR1 knock-out mice. Our findings demonstrate an unexpected pathway specificity for the heterodendritic metaplasticity in CA1. That Schaffer collateral/commissural synapses in SR are particularly susceptible to such metaplasticity may reflect an important control of information processing in this pathway in addition to its sensitivity to neuroinflammation under disease conditions.
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Sateesh S, Abraham WC. Neurophysiological and molecular approaches to understanding the mechanisms of learning and memory. J R Soc N Z 2020. [DOI: 10.1080/03036758.2020.1796719] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Affiliation(s)
- Shruthi Sateesh
- Department of Psychology, Brain Health Research Centre, Brain Research New Zealand, University of Otago, Dunedin, New Zealand
| | - Wickliffe C. Abraham
- Department of Psychology, Brain Health Research Centre, Brain Research New Zealand, University of Otago, Dunedin, New Zealand
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Tumor Necrosis Factor-α-Mediated Metaplastic Inhibition of LTP Is Constitutively Engaged in an Alzheimer's Disease Model. J Neurosci 2019; 39:9083-9097. [PMID: 31570539 DOI: 10.1523/jneurosci.1492-19.2019] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2019] [Revised: 09/23/2019] [Accepted: 09/25/2019] [Indexed: 01/08/2023] Open
Abstract
LTP, a fundamental mechanism of learning and memory, is a highly regulated process. One form of regulation is metaplasticity (i.e., the activity-dependent and long-lasting changes in neuronal state that orchestrate the direction, magnitude, and persistence of future synaptic plasticity). We have previously described a heterodendritic metaplasticity effect, whereby strong high-frequency priming stimulation in stratum oriens inhibits subsequent LTP in the stratum radiatum of hippocampal area CA1, potentially by engagement of the enmeshed astrocytic network. This effect may occur due to neuron-glia interactions in response to priming stimulation that leads to the release of gliotransmitters. Here we found in male rats that TNFα and associated signal transduction enzymes, but not interleukin-1β (IL-1β), were responsible for mediating the metaplasticity effect. Replacing priming stimulation with TNFα incubation reproduced these effects. As TNFα levels are elevated in Alzheimer's disease, we examined whether heterodendritic metaplasticity is dysregulated in a transgenic mouse model of the disease, either before or after amyloid plaque formation. We showed that TNFα and IL-1β levels were significantly increased in aged but not young transgenic mice. Although control LTP was impaired in the young transgenic mice, it was not TNFα-dependent. In the older transgenic mice, however, LTP was impaired in a way that occluded further reduction by heterosynaptic metaplasticity, whereas LTP was entirely rescued by incubation with a TNFα antibody, but not an IL-1β antibody. Thus, TNFα mediates a heterodendritic metaplasticity in healthy rodents that becomes constitutively and selectively engaged in a mouse model of Alzheimer's disease.SIGNIFICANCE STATEMENT The proinflammatory cytokine TNFα is known to be capable of inhibiting LTP and is upregulated several-fold in brain tissue, serum, and CSF of Alzheimer's disease (AD) patients. However, the mechanistic roles played by TNFα in plasticity and AD remain poorly understood. Here we show that TNFα and its downstream signaling molecules p38 MAPK, ERK, and JNK contribute fundamentally to a long-range metaplastic inhibition of LTP in rats. Moreover, the impaired LTP in aged APP/PS1 mice is rescued by incubation with a TNFα antibody. Thus, there is an endogenous engagement of the metaplasticity mechanism in this mouse model of AD, supporting the idea that blocking TNFα might be of therapeutic benefit in the disease.
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Neurobiological systems in dyslexia. Trends Neurosci Educ 2019; 14:11-24. [DOI: 10.1016/j.tine.2018.12.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2017] [Revised: 09/13/2018] [Accepted: 12/12/2018] [Indexed: 12/12/2022]
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Interaction of DCF1 with ATP1B1 induces impairment in astrocyte structural plasticity via the P38 signaling pathway. Exp Neurol 2018; 302:214-229. [DOI: 10.1016/j.expneurol.2018.01.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2017] [Revised: 12/16/2017] [Accepted: 01/08/2018] [Indexed: 12/18/2022]
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Jammal L, Whalley B, Barkai E. Learning-induced modulation of the effect of neuroglial transmission on synaptic plasticity. J Neurophysiol 2018; 119:2373-2379. [PMID: 29561201 DOI: 10.1152/jn.00101.2018] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Training rats in a complex olfactory discrimination task results in acquisition of "rule learning" (learning how to learn), a term describing the capability to perform the task superbly. Such rule learning results in strengthening of both excitatory and inhibitory synaptic connections between neurons in the piriform cortex. Moreover, intrinsic excitability is also enhanced throughout the pyramidal neuron population. Surprisingly, the cortical network retains its stability under these long-term modifications. In particular, the susceptibility for long-term potentiation (LTP) induction, while decreased for a short time window, returns to almost its pretraining value, although significant strengthening of AMPA receptor-mediated glutamatergic transmission remains. Such network balance is essential for maintaining the single-cell modifications that underlie long-term memory while preventing hyperexcitability that would result in runaway synaptic activity. However, the mechanisms underlying the long-term maintenance of such balance have yet to be described. In this study, we explored the role of astrocyte-mediated gliotransmission in long-term maintenance of learning-induced modifications in susceptibility for LTP induction and control of the strength of synaptic inhibition. We show that blocking connexin 43 hemichannels, which form gap junctions between astrocytes, decreases significantly the ability to induce LTP by stimulating the excitatory connections between piriform cortex pyramidal neurons after learning only. In parallel, spontaneous miniature inhibitory postsynaptic current amplitude is reduced in neurons from trained rats only, to the level of prelearning. Thus gliotransmission has a key role in maintaining learning-induced cortical stability by a wide-ranged control on synaptic transmission and plasticity. NEW & NOTEWORTHY We explore the role of astrocyte-mediated gliotransmission in maintenance of olfactory discrimination learning-induced modifications. We show that blocking gap junctions between astrocytes decreases significantly the ability to induce long-term potentiation in the piriform cortex after learning only. In parallel, synaptic inhibition is reduced in neurons from trained rats only, to the level of prelearning. Thus gliotransmission has a key role in maintaining learning-induced cortical stability by a wide-ranged control on synaptic transmission and plasticity.
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Affiliation(s)
- Luna Jammal
- Sagol Department of Neurobiology, Faculty of Natural Sciences, University of Haifa , Haifa , Israel
| | - Ben Whalley
- School of Chemistry, Food & Nutritional Sciences and Pharmacy, The University of Reading, White Knights, Reading , United Kingdom
| | - Edi Barkai
- Sagol Department of Neurobiology, Faculty of Natural Sciences, University of Haifa , Haifa , Israel
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Singh A, Abraham WC. Astrocytes and synaptic plasticity in health and disease. Exp Brain Res 2017; 235:1645-1655. [PMID: 28299411 DOI: 10.1007/s00221-017-4928-1] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2016] [Accepted: 02/20/2017] [Indexed: 12/22/2022]
Abstract
Activity-dependent synaptic plasticity phenomena such as long-term potentiation and long-term depression are candidate mechanisms for storing information in the brain. Regulation of synaptic plasticity is critical for healthy cognition and learning and this is provided in part by metaplasticity, which can act to maintain synaptic transmission within a dynamic range and potentially prevent excitotoxicity. Metaplasticity mechanisms also allow neurons to integrate plasticity-associated signals over time. Interestingly, astrocytes appear to be critical for certain forms of synaptic plasticity and metaplasticity mechanisms. Synaptic dysfunction is increasingly viewed as an early feature of AD that is correlated with the severity of cognitive decline, and the development of these pathologies is correlated with a rise in reactive astrocytes. This review focuses on the contributions of astrocytes to synaptic plasticity and metaplasticity in normal tissue, and addresses whether astroglial pathology may lead to aberrant engagement of these mechanisms in neurological diseases such as Alzheimer's disease.
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Affiliation(s)
- A Singh
- Department of Psychology, Brain Health Research Centre, Brain Research New Zealand, University of Otago, Box 56, Dunedin, 9054, New Zealand
| | - Wickliffe C Abraham
- Department of Psychology, Brain Health Research Centre, Brain Research New Zealand, University of Otago, Box 56, Dunedin, 9054, New Zealand.
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Emmons-Bell M, Durant F, Hammelman J, Bessonov N, Volpert V, Morokuma J, Pinet K, Adams DS, Pietak A, Lobo D, Levin M. Gap Junctional Blockade Stochastically Induces Different Species-Specific Head Anatomies in Genetically Wild-Type Girardia dorotocephala Flatworms. Int J Mol Sci 2015; 16:27865-96. [PMID: 26610482 PMCID: PMC4661923 DOI: 10.3390/ijms161126065] [Citation(s) in RCA: 68] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2015] [Revised: 11/06/2015] [Accepted: 11/10/2015] [Indexed: 12/13/2022] Open
Abstract
The shape of an animal body plan is constructed from protein components encoded by the genome. However, bioelectric networks composed of many cell types have their own intrinsic dynamics, and can drive distinct morphological outcomes during embryogenesis and regeneration. Planarian flatworms are a popular system for exploring body plan patterning due to their regenerative capacity, but despite considerable molecular information regarding stem cell differentiation and basic axial patterning, very little is known about how distinct head shapes are produced. Here, we show that after decapitation in G. dorotocephala, a transient perturbation of physiological connectivity among cells (using the gap junction blocker octanol) can result in regenerated heads with quite different shapes, stochastically matching other known species of planaria (S. mediterranea, D. japonica, and P. felina). We use morphometric analysis to quantify the ability of physiological network perturbations to induce different species-specific head shapes from the same genome. Moreover, we present a computational agent-based model of cell and physical dynamics during regeneration that quantitatively reproduces the observed shape changes. Morphological alterations induced in a genomically wild-type G. dorotocephala during regeneration include not only the shape of the head but also the morphology of the brain, the characteristic distribution of adult stem cells (neoblasts), and the bioelectric gradients of resting potential within the anterior tissues. Interestingly, the shape change is not permanent; after regeneration is complete, intact animals remodel back to G. dorotocephala-appropriate head shape within several weeks in a secondary phase of remodeling following initial complete regeneration. We present a conceptual model to guide future work to delineate the molecular mechanisms by which bioelectric networks stochastically select among a small set of discrete head morphologies. Taken together, these data and analyses shed light on important physiological modifiers of morphological information in dictating species-specific shape, and reveal them to be a novel instructive input into head patterning in regenerating planaria.
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Affiliation(s)
- Maya Emmons-Bell
- Center for Regenerative and Developmental Biology and Department of Biology, Tufts University, 200 Boston Avenue, Suite 4600, Medford, MA 02155, USA; (M.E.-B.); (F.D.); (J.H.); (J.M.); (K.P.); (D.S.A.)
| | - Fallon Durant
- Center for Regenerative and Developmental Biology and Department of Biology, Tufts University, 200 Boston Avenue, Suite 4600, Medford, MA 02155, USA; (M.E.-B.); (F.D.); (J.H.); (J.M.); (K.P.); (D.S.A.)
| | - Jennifer Hammelman
- Center for Regenerative and Developmental Biology and Department of Biology, Tufts University, 200 Boston Avenue, Suite 4600, Medford, MA 02155, USA; (M.E.-B.); (F.D.); (J.H.); (J.M.); (K.P.); (D.S.A.)
| | - Nicholas Bessonov
- Institute of Problems of Mechanical Engineering, Russian Academy of Sciences, Saint Petersburg 199178, Russia;
| | - Vitaly Volpert
- Institut Camille Jordan, UMR 5208 CNRS, University Lyon 1, Villeurbanne 69622, France;
| | - Junji Morokuma
- Center for Regenerative and Developmental Biology and Department of Biology, Tufts University, 200 Boston Avenue, Suite 4600, Medford, MA 02155, USA; (M.E.-B.); (F.D.); (J.H.); (J.M.); (K.P.); (D.S.A.)
| | - Kaylinnette Pinet
- Center for Regenerative and Developmental Biology and Department of Biology, Tufts University, 200 Boston Avenue, Suite 4600, Medford, MA 02155, USA; (M.E.-B.); (F.D.); (J.H.); (J.M.); (K.P.); (D.S.A.)
| | - Dany S. Adams
- Center for Regenerative and Developmental Biology and Department of Biology, Tufts University, 200 Boston Avenue, Suite 4600, Medford, MA 02155, USA; (M.E.-B.); (F.D.); (J.H.); (J.M.); (K.P.); (D.S.A.)
| | | | - Daniel Lobo
- Department of Biological Sciences, University of Maryland Baltimore County, 1000 Hilltop Circle, Baltimore, MD 21250, USA;
| | - Michael Levin
- Center for Regenerative and Developmental Biology and Department of Biology, Tufts University, 200 Boston Avenue, Suite 4600, Medford, MA 02155, USA; (M.E.-B.); (F.D.); (J.H.); (J.M.); (K.P.); (D.S.A.)
- Correspondence: ; Tel.: +1-617-627-6161; Fax: +1-617-627-6121
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Astrocyte-mediated metaplasticity in the hippocampus: Help or hindrance? Neuroscience 2015; 309:113-24. [DOI: 10.1016/j.neuroscience.2015.08.035] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2014] [Revised: 08/03/2015] [Accepted: 08/17/2015] [Indexed: 12/22/2022]
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Hulme SR, Jones OD, Raymond CR, Sah P, Abraham WC. Mechanisms of heterosynaptic metaplasticity. Philos Trans R Soc Lond B Biol Sci 2013; 369:20130148. [PMID: 24298150 DOI: 10.1098/rstb.2013.0148] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Synaptic plasticity is fundamental to the neural processes underlying learning and memory. Interestingly, synaptic plasticity itself can be dynamically regulated by prior activity, in a process termed 'metaplasticity', which can be expressed both homosynaptically and heterosynaptically. Here, we focus on heterosynaptic metaplasticity, particularly long-range interactions between synapses spread across dendritic compartments, and review evidence for intracellular versus intercellular signalling pathways leading to this effect. Of particular interest is our previously reported finding that priming stimulation in stratum oriens of area CA1 in the hippocampal slice heterosynaptically inhibits subsequent long-term potentiation and facilitates long-term depression in stratum radiatum. As we have excluded the most likely intracellular signalling pathways that might mediate this long-range heterosynaptic effect, we consider the hypothesis that intercellular communication may be critically involved. This hypothesis is supported by the finding that extracellular ATP hydrolysis, and activation of adenosine A2 receptors are required to induce the metaplastic state. Moreover, delivery of the priming stimulation in stratum oriens elicited astrocytic calcium responses in stratum radiatum. Both the astrocytic responses and the metaplasticity were blocked by gap junction inhibitors. Taken together, these findings support a novel intercellular communication system, possibly involving astrocytes, being required for this type of heterosynaptic metaplasticity.
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Affiliation(s)
- Sarah R Hulme
- Department of Psychology and Brain Health Research Centre, University of Otago, , PO Box 56, Dunedin 9054, New Zealand
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