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Kreutz A, Hu G, Tokar E. Pluripotent Stem Cell-derived Dopaminergic Neurons for Studying Developmental Neurotoxicity. Stem Cell Rev Rep 2023; 19:2120-2130. [PMID: 37273171 PMCID: PMC10579108 DOI: 10.1007/s12015-023-10555-9] [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] [Accepted: 05/08/2023] [Indexed: 06/06/2023]
Abstract
With the vast number of chemicals in commerce, higher throughput strategies are needed to inform risk assessment. The field of toxicology is therefore moving away from traditional in vivo guideline studies towards in vitro new approach methodologies. There has been a great push for such a shift in the field of developmental neurotoxicity, where there is a particular lack of data. A battery of in vitro new approach methodologies has thus been developed to help fill this gap. Included in this battery are assays for numerous processes critical to neurodevelopment, such as proliferation, migration, and synaptogenesis. The current battery of developmental neurotoxicity new approach methodologies still lacks recapitulation of several critical neurodevelopmental processes, including development of neuronal subtypes. With their pluripotency, alongside other advantages, pluripotent stem cells (PSCs) are uniquely suited to address questions of developmental neurotoxicity, as they can recapitulate the different stages of human in vivo neurodevelopment. Among the various neuronal subtypes, development of dopaminergic neurons (DA) is perhaps the best understood and several approaches exist to differentiate PSCs into DA. Herein we review these approaches and propose utilizing PSCs for screening of the impact of environmental chemicals on development of DA. Related techniques and gaps in knowledge are also addressed.
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Affiliation(s)
- Anna Kreutz
- Mechanistic Toxicology Branch, Division of Translational Toxicology, NIEHS, Research Triangle Park, Durham, NC, 27709, USA.
- Epigenetics and Stem Cell Biology Laboratory, Division of Intramural Research, NIEHS, Research Triangle Park, Durham, NC, 27709, USA.
| | - Guang Hu
- Epigenetics and Stem Cell Biology Laboratory, Division of Intramural Research, NIEHS, Research Triangle Park, Durham, NC, 27709, USA
| | - Erik Tokar
- Mechanistic Toxicology Branch, Division of Translational Toxicology, NIEHS, Research Triangle Park, Durham, NC, 27709, USA
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Carson RA, Rudine AC, Tally SJ, Franks AL, Frahm KA, Waldman JK, Silswal N, Burale S, Phan JV, Chandran UR, Monaghan AP, DeFranco DB. Statins impact primary embryonic mouse neural stem cell survival, cell death, and fate through distinct mechanisms. PLoS One 2018; 13:e0196387. [PMID: 29738536 PMCID: PMC5940229 DOI: 10.1371/journal.pone.0196387] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2017] [Accepted: 04/12/2018] [Indexed: 12/11/2022] Open
Abstract
Statins inhibit HMG-CoA reductase, the rate-limiting enzyme in the cholesterol biosynthesis pathway (CBP), and are used for the prevention of cardiovascular disease. The anti-inflammatory effects of statins may also provide therapeutic benefits and have led to their use in clinical trials for preeclampsia, a pregnancy-associated inflammatory condition, despite their current classification as category X (i.e. contraindicated during pregnancy). In the developing neocortex, products of the CBP play essential roles in proliferation and differentiation of neural stem-progenitor cells (NSPCs). To understand how statins could impact the developing brain, we studied effects of pravastatin and simvastatin on primary embryonic NSPC survival, proliferation, global transcription, and cell fate in vitro. We found that statins dose dependently decrease NSPC expansion by promoting cell death and autophagy of NSPCs progressing through the G1 phase of the cell cycle. Genome-wide transcriptome analysis demonstrates an increase in expression of CBP genes following pravastatin treatment, through activation of the SREBP2 transcription factor. Co-treatment with farnesyl pyrophosphate (FPP), a CBP metabolite downstream of HMG-CoA reductase, reduces SREBP2 activation and pravastatin-induced PARP cleavage. Finally, pravastatin and simvastatin differentially alter NSPC cell fate and mRNA expression during differentiation, through a non-CBP dependent pathway.
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Affiliation(s)
- Ross A. Carson
- Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America
| | - Anthony C. Rudine
- Department of Pediatrics, Division of Newborn Medicine, Children’s Hospital of Pittsburgh, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America
| | - Serena J. Tally
- Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America
| | - Alexis L. Franks
- Department of Pediatrics, Division of Child Neurology, Children’s Hospital of Pittsburgh, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America
| | - Krystle A. Frahm
- Department of Medicine, Division of Endocrinology and Metabolism, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America
| | - Jacob K. Waldman
- Department of Biomedical Informatics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America
| | - Neerupma Silswal
- Department of Biomedical Sciences, University of Missouri Kansas City School of Medicine, Kansas City, Missouri, United States of America
| | - Suban Burale
- Department of Biomedical Sciences, University of Missouri Kansas City School of Medicine, Kansas City, Missouri, United States of America
| | - James V. Phan
- Department of Biomedical Sciences, University of Missouri Kansas City School of Medicine, Kansas City, Missouri, United States of America
| | - Uma R. Chandran
- Department of Biomedical Informatics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America
| | - A. Paula Monaghan
- Department of Biomedical Sciences, University of Missouri Kansas City School of Medicine, Kansas City, Missouri, United States of America
| | - Donald B. DeFranco
- Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America
- * E-mail:
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Azim K, Angonin D, Marcy G, Pieropan F, Rivera A, Donega V, Cantù C, Williams G, Berninger B, Butt AM, Raineteau O. Pharmacogenomic identification of small molecules for lineage specific manipulation of subventricular zone germinal activity. PLoS Biol 2017; 15:e2000698. [PMID: 28350803 PMCID: PMC5370089 DOI: 10.1371/journal.pbio.2000698] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2016] [Accepted: 02/21/2017] [Indexed: 11/18/2022] Open
Abstract
Strategies for promoting neural regeneration are hindered by the difficulty of manipulating desired neural fates in the brain without complex genetic methods. The subventricular zone (SVZ) is the largest germinal zone of the forebrain and is responsible for the lifelong generation of interneuron subtypes and oligodendrocytes. Here, we have performed a bioinformatics analysis of the transcriptome of dorsal and lateral SVZ in early postnatal mice, including neural stem cells (NSCs) and their immediate progenies, which generate distinct neural lineages. We identified multiple signaling pathways that trigger distinct downstream transcriptional networks to regulate the diversity of neural cells originating from the SVZ. Next, we used a novel in silico genomic analysis, searchable platform-independent expression database/connectivity map (SPIED/CMAP), to generate a catalogue of small molecules that can be used to manipulate SVZ microdomain-specific lineages. Finally, we demonstrate that compounds identified in this analysis promote the generation of specific cell lineages from NSCs in vivo, during postnatal life and adulthood, as well as in regenerative contexts. This study unravels new strategies for using small bioactive molecules to direct germinal activity in the SVZ, which has therapeutic potential in neurodegenerative diseases. The subventricular zone (SVZ) is the largest germinal zone of the postnatal and adult brain. It contains neural stem cells (NSCs) that give rise to neurons and oligodendrocytes (OLs) in a region-specific manner. Here, we use a bioinformatics approach to identify multiple signaling pathways that regulate the diversity of cell lineages that originate from different subregions of the SVZ. We further use a computational-based drug-discovery strategy to identify a catalogue of small molecules that can be used to manipulate the regionalization of the SVZ. We provide proof that, by administration of small molecules in vivo, it is possible to promote the specific generation of neurons and OLs from NSCs in both the postnatal and adult brain, as well as in regenerative contexts after lesion. This study unravels novel strategies for using small bioactive molecules to direct germinal activity in the SVZ, which has therapeutic potential in neurodegenerative diseases.
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Affiliation(s)
- Kasum Azim
- Brain Research Institute, University of Zürich/ETHZ, Zürich, Switzerland
- Adult Neurogenesis and Cellular Reprogramming, Institute of Physiological Chemistry, University Medical Centre of the Johannes Gutenberg University Mainz, Germany
- Focus Program Translational Neuroscience, Johannes Gutenberg University Mainz, Germany
- * E-mail: (KA); (OR); (AMB)
| | - Diane Angonin
- Univ Lyon, Université Claude Bernard Lyon 1, Inserm, Stem Cell and Brain Research Institute U1208, Bron, France
| | - Guillaume Marcy
- Univ Lyon, Université Claude Bernard Lyon 1, Inserm, Stem Cell and Brain Research Institute U1208, Bron, France
| | - Francesca Pieropan
- School of Pharmacy and Biomedical Sciences, University of Portsmouth, Portsmouth, United Kingdom
| | - Andrea Rivera
- School of Pharmacy and Biomedical Sciences, University of Portsmouth, Portsmouth, United Kingdom
| | - Vanessa Donega
- Univ Lyon, Université Claude Bernard Lyon 1, Inserm, Stem Cell and Brain Research Institute U1208, Bron, France
| | | | - Gareth Williams
- Wolfson Centre for Age-Related Diseases, King's College London, Guy's Campus, London, United Kingdom
| | - Benedikt Berninger
- Adult Neurogenesis and Cellular Reprogramming, Institute of Physiological Chemistry, University Medical Centre of the Johannes Gutenberg University Mainz, Germany
- Focus Program Translational Neuroscience, Johannes Gutenberg University Mainz, Germany
| | - Arthur M. Butt
- School of Pharmacy and Biomedical Sciences, University of Portsmouth, Portsmouth, United Kingdom
- * E-mail: (KA); (OR); (AMB)
| | - Olivier Raineteau
- Brain Research Institute, University of Zürich/ETHZ, Zürich, Switzerland
- Univ Lyon, Université Claude Bernard Lyon 1, Inserm, Stem Cell and Brain Research Institute U1208, Bron, France
- * E-mail: (KA); (OR); (AMB)
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Quinolinic acid neurotoxicity: Differential roles of astrocytes and microglia via FGF-2-mediated signaling in redox-linked cytoskeletal changes. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2016; 1863:3001-3014. [PMID: 27663072 DOI: 10.1016/j.bbamcr.2016.09.014] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/20/2016] [Revised: 09/12/2016] [Accepted: 09/17/2016] [Indexed: 11/24/2022]
Abstract
QUIN is a glutamate agonist playing a role in the misregulation of the cytoskeleton, which is associated with neurodegeneration in rats. In this study, we focused on microglial activation, FGF2/Erk signaling, gap junctions (GJs), inflammatory parameters and redox imbalance acting on cytoskeletal dynamics of the in QUIN-treated neural cells of rat striatum. FGF-2/Erk signaling was not altered in QUIN-treated primary astrocytes or neurons, however cytoskeleton was disrupted. In co-cultured astrocytes and neurons, QUIN-activated FGF2/Erk signaling prevented the cytoskeleton from remodeling. In mixed cultures (astrocyte, neuron, microglia), QUIN-induced FGF-2 increased level failed to activate Erk and promoted cytoskeletal destabilization. The effects of QUIN in mixed cultures involved redox imbalance upstream of Erk activation. Decreased connexin 43 (Cx43) immunocontent and functional GJs, was also coincident with disruption of the cytoskeleton in primary astrocytes and mixed cultures. We postulate that in interacting astrocytes and neurons the cytoskeleton is preserved against the insult of QUIN by activation of FGF-2/Erk signaling and proper cell-cell interaction through GJs. In mixed cultures, the FGF-2/Erk signaling is blocked by the redox imbalance associated with microglial activation and disturbed cell communication, disrupting the cytoskeleton. Thus, QUIN signal activates differential mechanisms that could stabilize or destabilize the cytoskeleton of striatal astrocytes and neurons in culture, and glial cells play a pivotal role in these responses preserving or disrupting a combination of signaling pathways and cell-cell interactions. Taken together, our findings shed light into the complex role of the active interaction of astrocytes, neurons and microglia in the neurotoxicity of QUIN.
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Bian X, Zhong H, Li F, Cai Y, Li X, Wang L, Fan X. LXR agonist rescued the deficit in the proliferation of the cerebellar granule cells induced by dexamethasone. Biochem Biophys Res Commun 2016; 477:826-833. [PMID: 27369072 DOI: 10.1016/j.bbrc.2016.06.142] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2016] [Accepted: 06/27/2016] [Indexed: 12/16/2022]
Abstract
Dexamethasone (DEX) exposure during early postnatal life produces permanent neuromotor and intellectual deficits and stunts cerebellar growth. The liver X receptor (LXR) plays important roles in CNS development. However, the effects of LXR on the DEX-mediated impairment of cerebellar development remain undetermined. Thus, mice were pretreated with LXR agonist TO901317 (TO) and were later exposed to DEX to evaluate its protective effects on DEX-mediated deficit during cerebellar development. The results showed that an acute exposure of DEX on postnatal day 7 resulted in a significant impairment in cerebellar development and decreased the proliferation of granule neuron precursors in the external granule layer of cerebellum. This effect was attenuated by pretreatment with TO. We further found that the decrease in the proliferation caused by DEX occurred via up-regulation of glucocorticoid receptor and p27kip1, which could be partially prevented by LXR agonist pretreatment. Overall, our results suggest that LXR agonist pretreatment could protect against DEX-induced deficits in cerebellar development in postnatal mice and may thus be perspective recruited to counteract such GC side effects.
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Affiliation(s)
- Xuting Bian
- Department of Developmental Neuropsychology, School of Psychology, Third Military Medical University, Chongqing, 400038, China
| | - Hongyu Zhong
- Department of Developmental Neuropsychology, School of Psychology, Third Military Medical University, Chongqing, 400038, China
| | - Fen Li
- Department of Developmental Neuropsychology, School of Psychology, Third Military Medical University, Chongqing, 400038, China
| | - Yulong Cai
- Department of Developmental Neuropsychology, School of Psychology, Third Military Medical University, Chongqing, 400038, China
| | - Xin Li
- Department of Developmental Neuropsychology, School of Psychology, Third Military Medical University, Chongqing, 400038, China
| | - Lian Wang
- Department of Developmental Neuropsychology, School of Psychology, Third Military Medical University, Chongqing, 400038, China
| | - Xiaotang Fan
- Department of Developmental Neuropsychology, School of Psychology, Third Military Medical University, Chongqing, 400038, China.
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Yamashita S, Chiyonobu T, Yoshida M, Maeda H, Zuiki M, Kidowaki S, Isoda K, Morimoto M, Kato M, Saitsu H, Matsumoto N, Nakahata T, Saito MK, Hosoi H. Mislocalization of syntaxin-1 and impaired neurite growth observed in a human iPSC model for STXBP1-related epileptic encephalopathy. Epilepsia 2016; 57:e81-6. [PMID: 26918652 DOI: 10.1111/epi.13338] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/21/2016] [Indexed: 11/29/2022]
Abstract
Syntaxin-binding protein 1 (STXBP1) is essential for synaptic vesicle exocytosis. Mutations of its encoding gene, STXBP1, are among the most frequent genetic causes of epileptic encephalopathies. However, the precise pathophysiology of STXBP1 haploinsufficiency has not been elucidated. Using patient-derived induced pluripotent stem cells (iPSCs), we aimed to establish a neuronal model for STXBP1 haploinsufficiency and determine the pathophysiologic basis for STXBP1 encephalopathy. We generated iPSC lines from a patient with Ohtahara syndrome (OS) harboring a heterozygous nonsense mutation of STXBP1 (c.1099C>T; p.R367X) and performed neuronal differentiation. Both STXBP1 messenger RNA (mRNA) and STXBP1 protein expression levels of OS-derived neurons were approximately 50% lower than that of control-derived neurons, suggesting that OS-derived neurons are a suitable model for elucidating the pathophysiology of STXBP1 haploinsufficiency. Through Western blot and immunocytochemistry assays, we found that OS-derived neurons show reduced levels and mislocalization of syntaxin-1, a component of soluble N-ethylmaleimide-sensitive factor attachment receptor (SNARE) proteins. In addition, OS-derived neurons have impaired neurite outgrowth. In conclusion, this model enables us to investigate the neurobiology of STXBP1 encephalopathy throughout the stages of neurodevelopment. Reduced expression of STXBP1 leads to changes in the expression and localization of syntaxin-1 that may contribute to the devastating phenotype of STXBP1 encephalopathy.
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Affiliation(s)
- Satoshi Yamashita
- Department of Pediatrics, Kyoto Prefectural University of Medicine, Kyoto, Japan
| | - Tomohiro Chiyonobu
- Department of Pediatrics, Kyoto Prefectural University of Medicine, Kyoto, Japan
| | - Michiko Yoshida
- Department of Pediatrics, Kyoto Prefectural University of Medicine, Kyoto, Japan.,Department of Clinical Application, Center for iPS Cell Research and Application (CiRA), Kyoto University, Kyoto, Japan
| | - Hiroshi Maeda
- Department of Pediatrics, Kyoto Prefectural University of Medicine, Kyoto, Japan
| | - Masashi Zuiki
- Department of Pediatrics, Kyoto Prefectural University of Medicine, Kyoto, Japan
| | - Satoshi Kidowaki
- Department of Pediatrics, Kyoto Prefectural University of Medicine, Kyoto, Japan
| | - Kenichi Isoda
- Department of Pediatrics, Kyoto Prefectural University of Medicine, Kyoto, Japan.,Department of Clinical Application, Center for iPS Cell Research and Application (CiRA), Kyoto University, Kyoto, Japan
| | - Masafumi Morimoto
- Department of Pediatrics, Kyoto Prefectural University of Medicine, Kyoto, Japan
| | - Mitsuhiro Kato
- Department of Pediatrics, Yamagata University Faculty of Medicine, Yamagata, Japan
| | - Hirotomo Saitsu
- Department of Human Genetics, Yokohama City University Graduate School of Medicine, Yokohama, Japan
| | - Naomichi Matsumoto
- Department of Human Genetics, Yokohama City University Graduate School of Medicine, Yokohama, Japan
| | - Tatsutoshi Nakahata
- Department of Clinical Application, Center for iPS Cell Research and Application (CiRA), Kyoto University, Kyoto, Japan
| | - Megumu K Saito
- Department of Clinical Application, Center for iPS Cell Research and Application (CiRA), Kyoto University, Kyoto, Japan
| | - Hajime Hosoi
- Department of Pediatrics, Kyoto Prefectural University of Medicine, Kyoto, Japan
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Neural Differentiation of Human Pluripotent Stem Cells for Nontherapeutic Applications: Toxicology, Pharmacology, and In Vitro Disease Modeling. Stem Cells Int 2015; 2015:105172. [PMID: 26089911 PMCID: PMC4454762 DOI: 10.1155/2015/105172] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2015] [Revised: 05/06/2015] [Accepted: 05/12/2015] [Indexed: 02/08/2023] Open
Abstract
Human pluripotent stem cells (hPSCs) derived from either blastocyst stage embryos (hESCs) or reprogrammed somatic cells (iPSCs) can provide an abundant source of human neuronal lineages that were previously sourced from human cadavers, abortuses, and discarded surgical waste. In addition to the well-known potential therapeutic application of these cells in regenerative medicine, these are also various promising nontherapeutic applications in toxicological and pharmacological screening of neuroactive compounds, as well as for in vitro modeling of neurodegenerative and neurodevelopmental disorders. Compared to alternative research models based on laboratory animals and immortalized cancer-derived human neural cell lines, neuronal cells differentiated from hPSCs possess the advantages of species specificity together with genetic and physiological normality, which could more closely recapitulate in vivo conditions within the human central nervous system. This review critically examines the various potential nontherapeutic applications of hPSC-derived neuronal lineages and gives a brief overview of differentiation protocols utilized to generate these cells from hESCs and iPSCs.
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Vella J, Zammit C, Di Giovanni G, Muscat R, Valentino M. The central role of aquaporins in the pathophysiology of ischemic stroke. Front Cell Neurosci 2015; 9:108. [PMID: 25904843 PMCID: PMC4389728 DOI: 10.3389/fncel.2015.00108] [Citation(s) in RCA: 84] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2015] [Accepted: 04/10/2015] [Indexed: 11/16/2022] Open
Abstract
Stroke is a complex and devastating neurological condition with limited treatment options. Brain edema is a serious complication of stroke. Early edema formation can significantly contribute to infarct formation and thus represents a promising target. Aquaporin (AQP) water channels contribute to water homeostasis by regulating water transport and are implicated in several disease pathways. At least 7 AQP subtypes have been identified in the rodent brain and the use of transgenic mice has greatly aided our understanding of their functions. AQP4, the most abundant channel in the brain, is up-regulated around the peri-infarct border in transient cerebral ischemia and AQP4 knockout mice demonstrate significantly reduced cerebral edema and improved neurological outcome. In models of vasogenic edema, brain swelling is more pronounced in AQP4-null mice than wild-type providing strong evidence of the dual role of AQP4 in the formation and resolution of both vasogenic and cytotoxic edema. AQP4 is co-localized with inwardly rectifying K(+)-channels (Kir4.1) and glial K(+) uptake is attenuated in AQP4 knockout mice compared to wild-type, indicating some form of functional interaction. AQP4-null mice also exhibit a reduction in calcium signaling, suggesting that this channel may also be involved in triggering pathological downstream signaling events. Associations with the gap junction protein Cx43 possibly recapitulate its role in edema dissipation within the astroglial syncytium. Other roles ascribed to AQP4 include facilitation of astrocyte migration, glial scar formation, modulation of inflammation and signaling functions. Treatment of ischemic cerebral edema is based on the various mechanisms in which fluid content in different brain compartments can be modified. The identification of modulators and inhibitors of AQP4 offer new therapeutic avenues in the hope of reducing the extent of morbidity and mortality in stroke.
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Affiliation(s)
| | | | | | | | - Mario Valentino
- Department of Physiology and Biochemistry, University of MaltaMsida, Malta
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Post-status epilepticus treatment with the cannabinoid agonist WIN 55,212-2 prevents chronic epileptic hippocampal damage in rats. Neurobiol Dis 2014; 73:356-65. [PMID: 25447228 DOI: 10.1016/j.nbd.2014.10.018] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2014] [Revised: 10/13/2014] [Accepted: 10/17/2014] [Indexed: 12/12/2022] Open
Abstract
Repeated seizures are often associated with development of refractory chronic epilepsy, the most common form of which is temporal lobe epilepsy. G-protein-coupled cannabinoid receptors (CB1 and CB2 receptors) regulate neuronal excitability and have been shown to mediate acute anticonvulsant effects of cannabinoids in animal models. However, the potential of cannabinoids to prevent chronic neuronal damage and development of epilepsy remains unexplored. We hypothesized that treatment with a CB receptor agonist after an episode of status epilepticus--but before development of spontaneous recurrent seizures--might prevent the development of functional changes that lead to chronic epilepsy. Using the rat pilocarpine model, a therapeutic approach was simulated by administering the CB agonist, WIN 55,212-2 after an episode of status epilepticus. Epileptic behavior was monitored during development of spontaneous recurrent seizures for up to 6 months. Histology, neurochemistry, redox status and NMDA receptor subunit expression were assessed at 6 months after pilocarpine-induced seizures. Sub-acute treatment with WIN 55,212-2 (for 15 days starting 24h after PILO injection) dramatically attenuated the severity, duration and frequency of spontaneous recurrent seizures. Further, in contrast to vehicle-treated animals, hippocampi from WIN 55,212-2-treated animals showed: normal thiol redox state, normal NR2A and NR2B subunit expression, preservation of GABAergic neurons and prevention of abnormal proliferation of GABAergic progenitors. This study shows for the first time that, after a known inciting event, treatment with a compound targeting CB receptors has the potential to prevent the epileptogenic events that result in chronic epileptic damage.
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