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Melin E, Andersson M, Gøtzsche CR, Wickham J, Huang Y, Szczygiel JA, Boender A, Christiansen SH, Pinborg L, Woldbye DPD, Kokaia M. Combinatorial gene therapy for epilepsy: Gene sequence positioning and AAV serotype influence expression and inhibitory effect on seizures. Gene Ther 2023; 30:649-658. [PMID: 37029201 PMCID: PMC10457185 DOI: 10.1038/s41434-023-00399-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2021] [Revised: 02/24/2023] [Accepted: 03/16/2023] [Indexed: 04/09/2023]
Abstract
Gene therapy with AAV vectors carrying genes for neuropeptide Y and its receptor Y2 has been shown to inhibit seizures in multiple animal models of epilepsy. It is however unknown how the AAV serotype or the sequence order of these two transgenes in the expression cassette affects the actual parenchymal gene expression levels and the seizure-suppressant efficacy. To address these questions, we compared three viral vector serotypes (AAV1, AAV2 and AAV8) and two transgene sequence orders (NPY-IRES-Y2 and Y2-IRES-NPY) in a rat model of acutely induced seizures. Wistar male rats were injected bilaterally with viral vectors and 3 weeks later acute seizures were induced by a subcutaneous injection of kainate. The latency until 1st motor seizure, time spent in motor seizure and latency to status epilepticus were measured to evaluate the seizure-suppressing efficacy of these vectors compared to an empty cassette control vector. Based on the results, the effect of the AAV1-NPY-IRES-Y2 vector was further investigated by in vitro electrophysiology, and its ability to achieve transgene overexpression in resected human hippocampal tissue was evaluated. The AAV1-NPY-IRES-Y2 proved to be better to any other serotype or gene sequence considering both transgene expression and ability to suppress induced seizures in rats. The vector also demonstrated transgene-induced decrease of glutamate release from excitatory neuron terminals and significantly increased both NPY and Y2 expression in resected human hippocampal tissue from patients with drug-resistant temporal lobe epilepsy. These results validate the feasibility of NPY/Y2 receptor gene therapy as a therapeutic opportunity in focal epilepsies.
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Affiliation(s)
- Esbjörn Melin
- Experimental Epilepsy Group, Epilepsy Centre, Lund University Hospital, 17 Sölvegatan, 221 84, Lund, Sweden.
| | - My Andersson
- Experimental Epilepsy Group, Epilepsy Centre, Lund University Hospital, 17 Sölvegatan, 221 84, Lund, Sweden
| | - Casper R Gøtzsche
- CombiGene AB, Medicon Village, 2 Scheelevägen, 223 81, Lund, Sweden
- Department of Neuroscience, Panum Institute, University of Copenhagen, 3B Blegdamsvej, DK-2200, Copenhagen N, Denmark
| | - Jenny Wickham
- Experimental Epilepsy Group, Epilepsy Centre, Lund University Hospital, 17 Sölvegatan, 221 84, Lund, Sweden
| | - Yuzhe Huang
- Department of Neuroscience, Panum Institute, University of Copenhagen, 3B Blegdamsvej, DK-2200, Copenhagen N, Denmark
| | - Julia Alicja Szczygiel
- Department of Neuroscience, Panum Institute, University of Copenhagen, 3B Blegdamsvej, DK-2200, Copenhagen N, Denmark
| | - Arnie Boender
- Experimental Epilepsy Group, Epilepsy Centre, Lund University Hospital, 17 Sölvegatan, 221 84, Lund, Sweden
| | - Søren H Christiansen
- Department of Neuroscience, Panum Institute, University of Copenhagen, 3B Blegdamsvej, DK-2200, Copenhagen N, Denmark
| | - Lars Pinborg
- Department of Neurology and Neurobiology Research Unit, Copenhagen University Hospital, Rigshospitalet, 9 Blegdamsvej, DK-2100, Copenhagen, Denmark
| | - David P D Woldbye
- Department of Neuroscience, Panum Institute, University of Copenhagen, 3B Blegdamsvej, DK-2200, Copenhagen N, Denmark
| | - Merab Kokaia
- Experimental Epilepsy Group, Epilepsy Centre, Lund University Hospital, 17 Sölvegatan, 221 84, Lund, Sweden
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Abstract
Electrophysiological technique is an efficient tool for investigating the synaptic regulatory effects mediated by the endocannabinoid system. Stimulation of presynaptic type 1 cannabinoid receptor (CB1) is the principal mode by which endocannabinoids suppress transmitter release in the central nervous system, but a non-retrograde manner of functioning and other receptors have also been described. Endocannabinoids are key modulators of both short- and long-term plasticity. Here, we discuss ex vivo electrophysiological approaches to examine synaptic signaling induced by cannabinoid and endocannabinoid molecules in the mammalian brain.
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Affiliation(s)
- Alessandra Musella
- Synaptic Immunopathology Lab, IRCCS San Raffaele Roma, Rome, Italy
- Department of Human Sciences and Quality of Life Promotion University of Rome San Raffaele, Rome, Italy
| | - Diego Centonze
- Department of Systems Medicine, Tor Vergata University, Rome, Italy.
- Unit of Neurology, IRCCS Neuromed, Pozzilli, IS, Italy.
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Smith NA, Bekar LK, Nedergaard M. Astrocytic Endocannabinoids Mediate Hippocampal Transient Heterosynaptic Depression. Neurochem Res 2019; 45:100-108. [PMID: 31254249 DOI: 10.1007/s11064-019-02834-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2019] [Revised: 06/14/2019] [Accepted: 06/20/2019] [Indexed: 12/29/2022]
Abstract
Astrocytes are highly dynamic cells that modulate synaptic transmission within a temporal domain of seconds to minutes in physiological contexts such as Long-Term Potentiation (LTP) and Heterosynaptic Depression (HSD). Recent studies have revealed that astrocytes also modulate a faster form of synaptic activity (milliseconds to seconds) known as Transient Heterosynaptic Depression (tHSD). However, the mechanism underlying astrocytic modulation of tHSD is not fully understood. Are the traditional gliotransmitters ATP or glutamate released via hemichannels/vesicles or are other, yet, unexplored pathways involved? Using various approaches to manipulate astrocytes, including the Krebs cycle inhibitor fluoroacetate, connexin 43/30 double knockout mice (hemichannels), and inositol triphosphate type-2 receptor knockout mice, we confirmed early reports demonstrating that astrocytes are critical for tHSD. We also confirmed the importance of group II metabotropic glutamate receptors (mGluRs) in astrocytic modulation of tHSD using a group II agonist. Using dominant negative SNARE mice, which have disrupted glial vesicle function, we also found that vesicular release of gliotransmitters and activation of adenosine A1 receptors are not required for tHSD. As astrocytes can release lipids upon receptor stimulation, we asked if astrocyte-derived endocannabinoids are involved in tHSD. Interestingly, a cannabinoid receptor 1 (CB1R) antagonist blocked and an inhibitor of the endogenous endocannabinoid 2-arachidonyl glycerol (2-AG) degradation potentiates tHSD in hippocampal slices. Taken together, this study provides the first evidence for group II mGluR-mediated astrocytic endocannabinoids in transiently suppressing presynaptic neurotransmitter release associated with the phenomenon of tHSD.
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Affiliation(s)
- Nathan A Smith
- Division of Glia Disease and Therapeutics, Dept. of Neurosurgery, Center for Translational Neuromedicine, School of Medicine and Dentistry, University of Rochester, Rochester, NY, 14642, USA.
- Center for Neuroscience, Children's Research Institute, Children's National Medical Center, 111 Michigan Ave, Washington, NW, 20010, USA.
- George Washington University School of Medicine and Health Sciences, Washington, DC, 20052, USA.
| | - Lane K Bekar
- Department of Anatomy, Physiology and Pharmacology, University of Saskatchewan, Saskatoon, SK, S7N 5E5, Canada
| | - Maiken Nedergaard
- Division of Glia Disease and Therapeutics, Dept. of Neurosurgery, Center for Translational Neuromedicine, School of Medicine and Dentistry, University of Rochester, Rochester, NY, 14642, USA
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Gustafsson B, Ma R, Hanse E. The Small and Dynamic Pre-primed Pool at the Release Site; A Useful Concept to Understand Release Probability and Short-Term Synaptic Plasticity? Front Synaptic Neurosci 2019; 11:7. [PMID: 30899219 PMCID: PMC6416800 DOI: 10.3389/fnsyn.2019.00007] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2018] [Accepted: 02/20/2019] [Indexed: 11/23/2022] Open
Abstract
Advanced imaging techniques have revealed that synapses contain nanomodules in which pre- and post-synaptic molecules are brought together to form an integrated subsynaptic component for vesicle release and transmitter reception. Based on data from an electrophysiological study of ours in which release from synapses containing a single nanomodule was induced by brief 50 Hz trains using minimal stimulation, and on data from such imaging studies, we present a possible modus operandi of such a nanomodule. We will describe the techniques and tools used to obtain and analyze the electrophysiological data from single CA3–CA1 hippocampal synapses from the neonatal rat brain. This analysis leads to the proposal that a nanomodule, despite containing a number of release locations, operates as a single release site, releasing at most a single vesicle at a time. In this nanomodule there appears to be two separate sets of release locations, one set that is responsible for release in response to the first few action potentials and another set that produces the release thereafter. The data also suggest that vesicles at the first set of release locations are primed by synaptic inactivity lasting seconds, this synaptic inactivity also resulting in a large heterogeneity in the values for vesicle release probability among the synapses. The number of vesicles being primed at this set of release locations prior to the arrival of an action potential is small (0–3) and varies from train to train. Following the first action potential, this heterogeneity in vesicle release probability largely vanishes in a release-independent manner, shaping a variation in paired-pulse plasticity among the synapses. After the first few action potentials release is produced from the second set of release locations, and is given by vesicles that have been recruited after the onset of synaptic activity. This release depends on the number of such release locations and the recruitment to such a location. The initial heterogeneity in vesicle release probability, its disappearance after a single action potential, and variation in the recruitment to the second set of release locations are instrumental in producing the heterogeneity in short-term synaptic plasticity among these synapses, and can be seen as means to create differential dynamics within a synapse population.
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Affiliation(s)
- Bengt Gustafsson
- Department of Physiology, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Rong Ma
- Department of Physiology, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Eric Hanse
- Department of Physiology, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
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Tsai SF, Wu HT, Chen PC, Chen YW, Yu M, Wang TF, Wu SY, Tzeng SF, Kuo YM. High-fat diet suppresses the astrocytic process arborization and downregulates the glial glutamate transporters in the hippocampus of mice. Brain Res 2018; 1700:66-77. [DOI: 10.1016/j.brainres.2018.07.017] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2018] [Revised: 07/11/2018] [Accepted: 07/12/2018] [Indexed: 01/02/2023]
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Hedegaard A, Lehnhoff J, Moldovan M, Grøndahl L, Petersen NC, Meehan CF. Postactivation depression of the Ia EPSP in motoneurons is reduced in both the G127X SOD1 model of amyotrophic lateral sclerosis and in aged mice. J Neurophysiol 2015; 114:1196-210. [PMID: 26084911 DOI: 10.1152/jn.00745.2014] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2014] [Accepted: 06/17/2015] [Indexed: 12/14/2022] Open
Abstract
Postactivation depression (PActD) of Ia afferent excitatory postsynaptic potentials (EPSPs) in spinal motoneurons results in a long-lasting depression of the stretch reflex. This phenomenon (PActD) is of clinical interest as it has been shown to be reduced in a number of spastic disorders. Using in vivo intracellular recordings of Ia EPSPs in adult mice, we demonstrate that PActD in adult (100-220 days old) C57BL/6J mice is both qualitatively and quantitatively similar to that which has been observed in larger animals with respect to both the magnitude (with ∼20% depression of EPSPs at 0.5 ms after a train of stimuli) and the time course (returning to almost normal amplitudes by 5 ms after the train). This validates the use of mouse models to study PActD. Changes in such excitatory inputs to spinal motoneurons may have important implications for hyperreflexia and/or glutamate-induced excitotoxicity in the neurodegenerative disease amyotrophic lateral sclerosis (ALS). With the use of the G127X SOD1 mutant mouse, an ALS model with a prolonged asymptomatic phase and fulminant symptom onset, we observed that PActD is significantly reduced at both presymptomatic (16% depression) and symptomatic (17.3% depression) time points compared with aged-matched controls (22.4% depression). The PActD reduction was not markedly altered by symptom onset. Comparing these PActD changes at the EPSP with the known effect of the depression on the monosynaptic reflex, we conclude that this is likely to have a much larger effect on the reflex itself (a 20-40% difference). Nevertheless, it should also be accounted that in aged (580 day old) C57BL/6J mice there was also a reduction in PActD although, aging is not usually associated with spasticity.
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Affiliation(s)
- A Hedegaard
- Department of Neuroscience and Pharmacology, University of Copenhagen, Panum Institute, Copenhagen, Denmark; and
| | - J Lehnhoff
- Department of Neuroscience and Pharmacology, University of Copenhagen, Panum Institute, Copenhagen, Denmark; and
| | - M Moldovan
- Department of Neuroscience and Pharmacology, University of Copenhagen, Panum Institute, Copenhagen, Denmark; and
| | - L Grøndahl
- Department of Neuroscience and Pharmacology, University of Copenhagen, Panum Institute, Copenhagen, Denmark; and
| | - N C Petersen
- Department of Neuroscience and Pharmacology, University of Copenhagen, Panum Institute, Copenhagen, Denmark; and Department of Nutrition, Exercise and Sports, University of Copenhagen, Panum Institute, Copenhagen, Denmark
| | - C F Meehan
- Department of Neuroscience and Pharmacology, University of Copenhagen, Panum Institute, Copenhagen, Denmark; and
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Bursting reverberation as a multiscale neuronal network process driven by synaptic depression-facilitation. PLoS One 2015; 10:e0124694. [PMID: 26017681 PMCID: PMC4446271 DOI: 10.1371/journal.pone.0124694] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2014] [Accepted: 03/06/2015] [Indexed: 11/19/2022] Open
Abstract
Neuronal networks can generate complex patterns of activity that depend on membrane properties of individual neurons as well as on functional synapses. To decipher the impact of synaptic properties and connectivity on neuronal network behavior, we investigate the responses of neuronal ensembles from small (5-30 cells in a restricted sphere) and large (acute hippocampal slice) networks to single electrical stimulation: in both cases, a single stimulus generated a synchronous long-lasting bursting activity. While an initial spike triggered a reverberating network activity that lasted 2-5 seconds for small networks, we found here that it lasted only up to 300 milliseconds in slices. To explain this phenomena present at different scales, we generalize the depression-facilitation model and extracted the network time constants. The model predicts that the reverberation time has a bell shaped relation with the synaptic density, revealing that the bursting time cannot exceed a maximum value. Furthermore, before reaching its maximum, the reverberation time increases sub-linearly with the synaptic density of the network. We conclude that synaptic dynamics and connectivity shape the mean burst duration, a property present at various scales of the networks. Thus bursting reverberation is a property of sufficiently connected neural networks, and can be generated by collective depression and facilitation of underlying functional synapses.
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De Pittà M, Volman V, Berry H, Parpura V, Volterra A, Ben-Jacob E. Computational quest for understanding the role of astrocyte signaling in synaptic transmission and plasticity. Front Comput Neurosci 2012; 6:98. [PMID: 23267326 PMCID: PMC3528083 DOI: 10.3389/fncom.2012.00098] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2012] [Accepted: 12/06/2012] [Indexed: 01/08/2023] Open
Abstract
The complexity of the signaling network that underlies astrocyte-synapse interactions may seem discouraging when tackled from a theoretical perspective. Computational modeling is challenged by the fact that many details remain hitherto unknown and conventional approaches to describe synaptic function are unsuitable to explain experimental observations when astrocytic signaling is taken into account. Supported by experimental evidence is the possibility that astrocytes perform genuine information processing by means of their calcium signaling and are players in the physiological setting of the basal tone of synaptic transmission. Here we consider the plausibility of this scenario from a theoretical perspective, focusing on the modulation of synaptic release probability by the astrocyte and its implications on synaptic plasticity. The analysis of the signaling pathways underlying such modulation refines our notion of tripartite synapse and has profound implications on our understanding of brain function.
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Affiliation(s)
- Maurizio De Pittà
- School of Physics and Astronomy, Tel Aviv University Ramat Aviv, Israel
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