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Riddle A, Srivastava T, Wang K, Tellez E, O'Neill H, Gong X, O'Niel A, Bell JA, Raber J, Lattal M, Maylie J, Back SA. Mild neonatal hypoxia disrupts adult hippocampal learning and memory and is associated with CK2-mediated dysregulation of synaptic calcium-activated potassium channel KCNN2. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.07.10.602558. [PMID: 39071376 PMCID: PMC11275740 DOI: 10.1101/2024.07.10.602558] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/30/2024]
Abstract
Objective Although nearly half of preterm survivors display persistent neurobehavioral dysfunction including memory impairment without overt gray matter injury, the underlying mechanisms of neuronal or glial dysfunction, and their relationship to commonly observed cerebral white matter injury are unclear. We developed a mouse model to test the hypothesis that mild hypoxia during preterm equivalence is sufficient to persistently disrupt hippocampal neuronal maturation related to adult cellular mechanisms of learning and memory. Methods: Neonatal (P2) mice were exposed to mild hypoxia (8%O 2 ) for 30 min and evaluated for acute injury responses or survived until adulthood for assessment of learning and memory and hippocampal neurodevelopment. Results Neonatal mild hypoxia resulted in clinically relevant oxygen desaturation and tachycardia without bradycardia and was not accompanied by cerebral gray or white matter injury. Neonatal hypoxia exposure was sufficient to cause hippocampal learning and memory deficits and abnormal maturation of CA1 neurons that persisted into adulthood. This was accompanied by reduced hippocampal CA3-CA1 synaptic strength and LTP and reduced synaptic activity of calcium-sensitive SK2 channels, key regulators of spike timing dependent neuroplasticity, including LTP. Structural illumination microscopy revealed reduced synaptic density, but intact SK2 localization at the synapse. Persistent loss of SK2 activity was mediated by altered casein kinase 2 (CK2) signaling. Interpretation Clinically relevant mild hypoxic exposure in the neonatal mouse is sufficient to produce morphometric and functional disturbances in hippocampal neuronal maturation independently of white matter injury. Additionally, we describe a novel persistent mechanism of potassium channel dysregulation after neonatal hypoxia. Collectively our findings suggest an unexplored explanation for the broad spectrum of neurobehavioral, cognitive and learning disabilities that paradoxically persist into adulthood without overt gray matter injury after preterm birth.
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Witteveen IF, McCoy E, Holsworth TD, Shen CZ, Chang W, Nance MG, Belkowitz AR, Dougald A, Puglia MH, Ribic A. Preterm birth accelerates the maturation of spontaneous and resting activity in the visual cortex. Front Integr Neurosci 2023; 17:1149159. [PMID: 37255843 PMCID: PMC10225509 DOI: 10.3389/fnint.2023.1149159] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2023] [Accepted: 04/25/2023] [Indexed: 06/01/2023] Open
Abstract
Prematurity is among the leading risks for poor neurocognitive outcomes. The brains of preterm infants show alterations in structure and electrical activity, but the underlying circuit mechanisms are unclear. To address this, we performed a cross-species study of the electrophysiological activity in the visual cortices of prematurely born infants and mice. Using electroencephalography (EEG) in a sample of healthy preterm (N = 29) and term (N = 28) infants, we found that the maturation of the aperiodic EEG component was accelerated in the preterm cohort, with a significantly flatter 1/f slope when compared to the term infants. The flatter slope was a result of decreased spectral power in the theta and alpha bands and was correlated with the degree of prematurity. To determine the circuit and cellular changes that potentially mediate the changes in 1/f slope after preterm birth, we used in vivo electrophysiology in preterm mice and found that, similar to infants, preterm birth results in a flattened 1/f slope. We analyzed neuronal activity in the visual cortex of preterm (N = 6) and term (N = 9) mice and found suppressed spontaneous firing of neurons. Using immunohistochemistry, we further found an accelerated maturation of inhibitory circuits. In both preterm mice and infants, the functional maturation of the cortex was accelerated, underscoring birth as a critical checkpoint in cortical maturation. Our study points to a potential mechanism of preterm birth-related changes in resting neural activity, highlighting the utility of a cross-species approach in studying the neural circuit mechanisms of preterm birth-related neurodevelopmental conditions.
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Affiliation(s)
- Isabelle F. Witteveen
- Department of Psychology, College and Graduate School of Arts and Sciences, University of Virginia, Charlottesville, VA, United States
| | - Emily McCoy
- Department of Psychology, College and Graduate School of Arts and Sciences, University of Virginia, Charlottesville, VA, United States
- Program in Fundamental Neuroscience, University of Virginia, Charlottesville, VA, United States
| | - Troy D. Holsworth
- Department of Psychology, College and Graduate School of Arts and Sciences, University of Virginia, Charlottesville, VA, United States
| | - Catherine Z. Shen
- Department of Psychology, College and Graduate School of Arts and Sciences, University of Virginia, Charlottesville, VA, United States
| | - Winnie Chang
- Department of Neurology, School of Medicine, University of Virginia, Charlottesville, VA, United States
| | - Madelyn G. Nance
- Department of Neurology, School of Medicine, University of Virginia, Charlottesville, VA, United States
| | - Allison R. Belkowitz
- Department of Neurology, School of Medicine, University of Virginia, Charlottesville, VA, United States
| | - Avery Dougald
- Department of Neurology, School of Medicine, University of Virginia, Charlottesville, VA, United States
| | - Meghan H. Puglia
- Program in Fundamental Neuroscience, University of Virginia, Charlottesville, VA, United States
- Department of Neurology, School of Medicine, University of Virginia, Charlottesville, VA, United States
| | - Adema Ribic
- Department of Psychology, College and Graduate School of Arts and Sciences, University of Virginia, Charlottesville, VA, United States
- Program in Fundamental Neuroscience, University of Virginia, Charlottesville, VA, United States
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Witteveen IF, McCoy E, Holsworth TD, Shen CZ, Chang W, Nance MG, Belkowitz AR, Dougald A, Puglia MH, Ribic A. Preterm birth accelerates the maturation of spontaneous and resting activity in the visual cortex. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.01.20.524993. [PMID: 36711801 PMCID: PMC9882279 DOI: 10.1101/2023.01.20.524993] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Prematurity is among the leading risks for poor neurocognitive outcomes. The brains of preterm infants show alterations in structure and electrical activity, but the underlying circuit mechanisms are unclear. To address this, we performed a cross-species study of the electrophysiological activity in the visual cortices of prematurely born infants and mice. Using electroencephalography (EEG) in a sample of healthy preterm (N=29) and term (N=28) infants, we found that the maturation of the aperiodic EEG component was accelerated in the preterm cohort, with a significantly flatter 1/f slope when compared to the term infants. The flatter slope was a result of decreased spectral power in the theta and alpha bands and was correlated with the degree of prematurity. To determine the circuit and cellular changes that potentially mediate the changes in 1/f slope after preterm birth, we used in vivo electrophysiology in preterm mice and found that, similar to infants, preterm birth results in a flattened 1/f slope. We analyzed neuronal activity in the visual cortex of preterm mice (N=6 preterm and 9 term mice) and found suppressed spontaneous firing of neurons. Using immunohistochemistry, we further found an accelerated maturation of inhibitory circuits. In both preterm mice and infants, the functional maturation of the cortex was accelerated, underscoring birth as a critical checkpoint in cortical maturation. Our study points to a potential mechanism of preterm birth-related changes in resting neural activity, highlighting the utility of a cross-species approach in studying the neural circuit mechanisms of preterm birth-related neurodevelopmental conditions.
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Affiliation(s)
- Isabelle F. Witteveen
- Department of Psychology, College and Graduate School of Arts and Sciences, University of Virginia, Charlottesville, VA 22904
| | - Emily McCoy
- Department of Psychology, College and Graduate School of Arts and Sciences, University of Virginia, Charlottesville, VA 22904
- Program in Fundamental Neuroscience, University of Virginia, Charlottesville, VA 22903
| | - Troy D. Holsworth
- Department of Psychology, College and Graduate School of Arts and Sciences, University of Virginia, Charlottesville, VA 22904
| | - Catherine Z. Shen
- Department of Psychology, College and Graduate School of Arts and Sciences, University of Virginia, Charlottesville, VA 22904
| | - Winnie Chang
- Department of Neurology, School of Medicine, University of Virginia, Charlottesville, VA 22903
| | - Madelyn G. Nance
- Department of Neurology, School of Medicine, University of Virginia, Charlottesville, VA 22903
| | - Allison R. Belkowitz
- Department of Neurology, School of Medicine, University of Virginia, Charlottesville, VA 22903
| | - Avery Dougald
- Department of Neurology, School of Medicine, University of Virginia, Charlottesville, VA 22903
| | - Meghan H. Puglia
- Program in Fundamental Neuroscience, University of Virginia, Charlottesville, VA 22903
- Department of Neurology, School of Medicine, University of Virginia, Charlottesville, VA 22903
| | - Adema Ribic
- Department of Psychology, College and Graduate School of Arts and Sciences, University of Virginia, Charlottesville, VA 22904
- Program in Fundamental Neuroscience, University of Virginia, Charlottesville, VA 22903
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Johnson KJ, Moy B, Rensing N, Robinson A, Ly M, Chengalvala R, Wong M, Galindo R. Functional neuropathology of neonatal hypoxia-ischemia by single-mouse longitudinal electroencephalography. Epilepsia 2022; 63:3037-3050. [PMID: 36054439 PMCID: PMC10176800 DOI: 10.1111/epi.17403] [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: 04/08/2022] [Revised: 08/26/2022] [Accepted: 08/26/2022] [Indexed: 01/11/2023]
Abstract
OBJECTIVE Neonatal cerebral hypoxia-ischemia (HI) results in symptomatic seizures and long-term neurodevelopmental disability. The Rice-Vannucci model of rodent neonatal HI has been used extensively to examine and translate the functional consequences of acute and chronic HI-induced encephalopathy. Yet, longitudinal electrophysiological characterization of this brain injury model has been limited by the size of the neonatal mouse's head and postnatal maternal dependency. We overcome this challenge by employing a novel method of longitudinal single-mouse electroencephalography (EEG) using chronically implanted subcranial electrodes in the term-equivalent mouse pup. We characterize the neurophysiological disturbances occurring during awake and sleep states in the acute and chronic phases following newborn brain injury. METHODS C57BL/6 mice underwent long-term bilateral subcranial EEG and electromyographic electrode placement at postnatal day 9 followed by unilateral carotid cauterization and exposure to 40 minutes of hypoxia the following day. EEG recordings were obtained prior, during, and intermittently after the HI procedure from postnatal day 10 to weaning age. Quantitative EEG and fast Fourier transform analysis were used to evaluate seizures, cortical cerebral dysfunction, and disturbances in vigilance states. RESULTS We observed neonatal HI-provoked electrographic focal and bilateral seizures during or immediately following global hypoxia and most commonly contralateral to the ischemic injury. Spontaneous chronic seizures were not seen. Injured mice developed long-term asymmetric EEG background attenuation in all frequencies and most prominently during non-rapid eye movement (NREM) sleep. HI mice also showed transient impairments in vigilance state duration and transitions during the first 2 days following injury. SIGNIFICANCE The functional burden of mouse neonatal HI recorded by EEG resembles closely that of the injured human newborn. The use of single-mouse longitudinal EEG in this immature model can advance our understanding of the developmental and pathophysiological mechanisms of neonatal cerebral injury and help translate novel therapeutic strategies against this devastating condition.
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Affiliation(s)
- Kevin J Johnson
- Department of Neurology, Division of Pediatric & Developmental Neurology, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Brianna Moy
- Department of Neurology, Division of Pediatric & Developmental Neurology, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Nicholas Rensing
- Department of Neurology, Division of Pediatric & Developmental Neurology, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Alexia Robinson
- Department of Neurology, Division of Pediatric & Developmental Neurology, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Michael Ly
- Department of Neurology, Division of Pediatric & Developmental Neurology, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Ramya Chengalvala
- Department of Neurology, Division of Pediatric & Developmental Neurology, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Michael Wong
- Department of Neurology, Division of Pediatric & Developmental Neurology, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Rafael Galindo
- Department of Neurology, Division of Pediatric & Developmental Neurology, Washington University School of Medicine, St. Louis, Missouri, USA
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Zayachkivsky A, Lehmkuhle MJ, Ekstrand JJ, Dudek FE. Background suppression of electrical activity is a potential biomarker of subsequent brain injury in a rat model of neonatal hypoxia-ischemia. J Neurophysiol 2022; 128:118-130. [PMID: 35675445 DOI: 10.1152/jn.00024.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Electrographic seizures and abnormal background activity in the neonatal electroencephalogram (EEG) may differentiate between harmful versus benign brain insults. Using two animal models of neonatal seizures, electrical activity was recorded in freely behaving rats and examined quantitatively during successive time periods with field-potential recordings obtained shortly after the brain insult (i.e., 0-4 days). Single-channel, differential recordings with miniature wireless telemetry were used to analyze spontaneous electrographic seizures and background suppression of electrical activity after 1) hypoxia-ischemia (HI), which is a model of neonatal encephalopathy that causes acute seizures and a large brain lesion with possible development of epilepsy, 2) hypoxia alone (Ha), which causes severe acute seizures without an obvious lesion or subsequent epilepsy, and 3) sham control rats. Background EEG exhibited increases in power as a function of age in control animals. Although background electrical activity was depressed in all frequency bands immediately after HI, suppression in the β and γ bands was greatest and lasted longest. Spontaneous electrographic seizures were recorded, but only in a few HI-treated animals. Ha-treated rat pups were similar to sham controls, they had no subsequent spontaneous electrographic seizures after the treatment and background suppression was only briefly observed in one frequency band. Thus, the normal age-dependent maturation of electrical activity patterns in control animals was significantly disrupted after HI. Suppression of the background EEG observed here after HI-induced acute seizures and subsequent brain injury may be a noninvasive biomarker for detecting severe brain injuries and may help predict subsequent epilepsy.NEW & NOTEWORTHY Biomarkers of neonatal brain injury are needed. Hypoxia-ischemia (HI) in immature rat pups caused severe brain injury, which was associated with strongly suppressed background EEG. The suppression was most robust in the β and γ bands; it started immediately after the HI injury and persisted for days. Thus, background suppression may be a noninvasive biomarker for detecting severe brain injuries and may help predict subsequent epilepsy.
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Affiliation(s)
- A Zayachkivsky
- Department of Neurosurgery, University of Utah School of Medicine, Salt Lake City, Utah
| | - M J Lehmkuhle
- Department of Neurosurgery, University of Utah School of Medicine, Salt Lake City, Utah
| | - J J Ekstrand
- Department of Pediatrics, University of Utah School of Medicine, Salt Lake City, Utah
| | - F E Dudek
- Department of Neurosurgery, University of Utah School of Medicine, Salt Lake City, Utah
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Wang Y, Wei P, Yan F, Luo Y, Zhao G. Animal Models of Epilepsy: A Phenotype-oriented Review. Aging Dis 2022; 13:215-231. [PMID: 35111370 PMCID: PMC8782545 DOI: 10.14336/ad.2021.0723] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2021] [Accepted: 07/23/2021] [Indexed: 12/26/2022] Open
Abstract
Epilepsy is a serious neurological disorder characterized by abnormal, recurrent, and synchronous discharges in the brain. Long-term recurrent seizure attacks can cause serious damage to brain function, which is usually observed in patients with temporal lobe epilepsy. Controlling seizure attacks is vital for the treatment and prognosis of epilepsy. Animal models, such as the kindling model, which was the most widely used model in the past, allow the understanding of the potential epileptogenic mechanisms and selection of antiepileptic drugs. In recent years, various animal models of epilepsy have been established to mimic different seizure types, without clear merits and demerits. Accordingly, this review provides a summary of the views mentioned above, aiming to provide a reference for animal model selection.
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Affiliation(s)
- Yilin Wang
- 2Institute of Cerebrovascular Diseases Research and Department of Neurology, Xuanwu Hospital, Capital Medical University, Beijing, China
| | - Penghu Wei
- 1Department of Neurosurgery, Xuanwu Hospital of Capital Medical University, Beijing, China.,4Clinical Research Center for Epilepsy Capital Medical University, Beijing, China
| | - Feng Yan
- 2Institute of Cerebrovascular Diseases Research and Department of Neurology, Xuanwu Hospital, Capital Medical University, Beijing, China
| | - Yumin Luo
- 2Institute of Cerebrovascular Diseases Research and Department of Neurology, Xuanwu Hospital, Capital Medical University, Beijing, China.,3Beijing Institute for Brain Disorders, Capital Medical University, Beijing, China.,4Clinical Research Center for Epilepsy Capital Medical University, Beijing, China
| | - Guoguang Zhao
- 1Department of Neurosurgery, Xuanwu Hospital of Capital Medical University, Beijing, China.,3Beijing Institute for Brain Disorders, Capital Medical University, Beijing, China.,4Clinical Research Center for Epilepsy Capital Medical University, Beijing, China
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Ala‐Kurikka T, Pospelov A, Summanen M, Alafuzoff A, Kurki S, Voipio J, Kaila K. A physiologically validated rat model of term birth asphyxia with seizure generation after, not during, brain hypoxia. Epilepsia 2021; 62:908-919. [PMID: 33338272 PMCID: PMC8246723 DOI: 10.1111/epi.16790] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2020] [Revised: 11/24/2020] [Accepted: 11/24/2020] [Indexed: 01/05/2023]
Abstract
OBJECTIVE Birth asphyxia (BA) is often associated with seizures that may exacerbate the ensuing hypoxic-ischemic encephalopathy. In rodent models of BA, exposure to hypoxia is used to evoke seizures, that commence already during the insult. This is in stark contrast to clinical BA, in which seizures are typically seen upon recovery. Here, we introduce a term-equivalent rat model of BA, in which seizures are triggered after exposure to asphyxia. METHODS Postnatal day 11-12 male rat pups were exposed to steady asphyxia (15 min; air containing 5% O2 + 20% CO2 ) or to intermittent asphyxia (30 min; three 5 + 5-min cycles of 9% and 5% O2 at 20% CO2 ). Cortical activity and electrographic seizures were recorded in freely behaving animals. Simultaneous electrode measurements of intracortical pH, Po2 , and local field potentials (LFPs) were made under urethane anesthesia. RESULTS Both protocols decreased blood pH to <7.0 and brain pH from 7.3 to 6.7 and led to a fall in base excess by 20 mmol·L-1 . Electrographic seizures with convulsions spanning the entire Racine scale were triggered after intermittent but not steady asphyxia. In the presence of 20% CO2 , brain Po2 was only transiently affected by 9% ambient O2 but fell below detection level during the steps to 5% O2 , and LFP activity was nearly abolished. Post-asphyxia seizures were strongly suppressed when brain pH recovery was slowed down by 5% CO2 . SIGNIFICANCE The rate of brain pH recovery has a strong influence on post-asphyxia seizure propensity. The recurring hypoxic episodes during intermittent asphyxia promote neuronal excitability, which leads to seizures only after the suppressing effect of the hypercapnic acidosis is relieved. The present rodent model of BA is to our best knowledge the first one in which, consistent with clinical BA, behavioral and electrographic seizures are triggered after and not during the BA-mimicking insult.
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Affiliation(s)
- Tommi Ala‐Kurikka
- Faculty of Biological and Environmental Sciences, Molecular and Integrative BiosciencesUniversity of HelsinkiHelsinkiFinland
- Neuroscience Center (HiLIFE)University of HelsinkiHelsinkiFinland
| | - Alexey Pospelov
- Faculty of Biological and Environmental Sciences, Molecular and Integrative BiosciencesUniversity of HelsinkiHelsinkiFinland
- Neuroscience Center (HiLIFE)University of HelsinkiHelsinkiFinland
| | - Milla Summanen
- Faculty of Biological and Environmental Sciences, Molecular and Integrative BiosciencesUniversity of HelsinkiHelsinkiFinland
- Neuroscience Center (HiLIFE)University of HelsinkiHelsinkiFinland
| | - Aleksander Alafuzoff
- Faculty of Biological and Environmental Sciences, Molecular and Integrative BiosciencesUniversity of HelsinkiHelsinkiFinland
- Neuroscience Center (HiLIFE)University of HelsinkiHelsinkiFinland
| | - Samu Kurki
- Faculty of Biological and Environmental Sciences, Molecular and Integrative BiosciencesUniversity of HelsinkiHelsinkiFinland
- Neuroscience Center (HiLIFE)University of HelsinkiHelsinkiFinland
| | - Juha Voipio
- Faculty of Biological and Environmental Sciences, Molecular and Integrative BiosciencesUniversity of HelsinkiHelsinkiFinland
| | - Kai Kaila
- Faculty of Biological and Environmental Sciences, Molecular and Integrative BiosciencesUniversity of HelsinkiHelsinkiFinland
- Neuroscience Center (HiLIFE)University of HelsinkiHelsinkiFinland
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Perinatal Brain Injury and Inflammation: Lessons from Experimental Murine Models. Cells 2020; 9:cells9122640. [PMID: 33302543 PMCID: PMC7764185 DOI: 10.3390/cells9122640] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2020] [Revised: 11/19/2020] [Accepted: 12/02/2020] [Indexed: 02/07/2023] Open
Abstract
Perinatal brain injury or neonatal encephalopathy (NE) is a state of disturbed neurological function in neonates, caused by a number of different aetiologies. The most prominent cause of NE is hypoxic ischaemic encephalopathy, which can often induce seizures. NE and neonatal seizures are both associated with poor neurological outcomes, resulting in conditions such as cerebral palsy, epilepsy, autism, schizophrenia and intellectual disability. The current treatment strategies for NE and neonatal seizures have suboptimal success in effectively treating neonates. Therapeutic hypothermia is currently used to treat NE and has been shown to reduce morbidity and has neuroprotective effects. However, its success varies between developed and developing countries, most likely as a result of lack of sufficient resources. The first-line pharmacological treatment for NE is phenobarbital, followed by phenytoin, fosphenytoin and lidocaine as second-line treatments. While these drugs are mostly effective at halting seizure activity, they are associated with long-lasting adverse neurological effects on development. Over the last years, inflammation has been recognized as a trigger of NE and seizures, and evidence has indicated that this inflammation plays a role in the long-term neuronal damage experienced by survivors. Researchers are therefore investigating the possible neuroprotective effects that could be achieved by using anti-inflammatory drugs in the treatment of NE. In this review we will highlight the current knowledge of the inflammatory response after perinatal brain injury and what we can learn from animal models.
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Menéndez Méndez A, Smith J, Engel T. Neonatal Seizures and Purinergic Signalling. Int J Mol Sci 2020; 21:ijms21217832. [PMID: 33105750 PMCID: PMC7660091 DOI: 10.3390/ijms21217832] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Revised: 10/18/2020] [Accepted: 10/20/2020] [Indexed: 02/07/2023] Open
Abstract
Neonatal seizures are one of the most common comorbidities of neonatal encephalopathy, with seizures aggravating acute injury and clinical outcomes. Current treatment can control early life seizures; however, a high level of pharmacoresistance remains among infants, with increasing evidence suggesting current anti-seizure medication potentiating brain damage. This emphasises the need to develop safer therapeutic strategies with a different mechanism of action. The purinergic system, characterised by the use of adenosine triphosphate and its metabolites as signalling molecules, consists of the membrane-bound P1 and P2 purinoreceptors and proteins to modulate extracellular purine nucleotides and nucleoside levels. Targeting this system is proving successful at treating many disorders and diseases of the central nervous system, including epilepsy. Mounting evidence demonstrates that drugs targeting the purinergic system provide both convulsive and anticonvulsive effects. With components of the purinergic signalling system being widely expressed during brain development, emerging evidence suggests that purinergic signalling contributes to neonatal seizures. In this review, we first provide an overview on neonatal seizure pathology and purinergic signalling during brain development. We then describe in detail recent evidence demonstrating a role for purinergic signalling during neonatal seizures and discuss possible purine-based avenues for seizure suppression in neonates.
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Affiliation(s)
- Aida Menéndez Méndez
- Department of Physiology and Medical Physics, RCSI University of Medicine and Health Sciences, Dublin D02 YN77, Ireland; (A.M.M.); (J.S.)
| | - Jonathon Smith
- Department of Physiology and Medical Physics, RCSI University of Medicine and Health Sciences, Dublin D02 YN77, Ireland; (A.M.M.); (J.S.)
- FutureNeuro, Science Foundation Ireland Research Centre for Chronic and Rare Neurological Diseases, RCSI University of Medicine and Health Sciences, Dublin D02 YN77, Ireland
| | - Tobias Engel
- Department of Physiology and Medical Physics, RCSI University of Medicine and Health Sciences, Dublin D02 YN77, Ireland; (A.M.M.); (J.S.)
- FutureNeuro, Science Foundation Ireland Research Centre for Chronic and Rare Neurological Diseases, RCSI University of Medicine and Health Sciences, Dublin D02 YN77, Ireland
- Correspondence: ; Tel.: +35-314-025-199
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Pospelov AS, Puskarjov M, Kaila K, Voipio J. Endogenous brain-sparing responses in brain pH and PO 2 in a rodent model of birth asphyxia. Acta Physiol (Oxf) 2020; 229:e13467. [PMID: 32174009 DOI: 10.1111/apha.13467] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2020] [Accepted: 03/11/2020] [Indexed: 12/12/2022]
Abstract
AIM To study brain-sparing physiological responses in a rodent model of birth asphyxia which reproduces the asphyxia-defining systemic hypoxia and hypercapnia. METHODS Steady or intermittent asphyxia was induced for 15-45 minutes in anaesthetized 6- and 11-days old rats and neonatal guinea pigs using gases containing 5% or 9% O2 plus 20% CO2 (in N2 ). Hypoxia and hypercapnia were induced with low O2 and high CO2 respectively. Oxygen partial pressure (PO2 ) and pH were measured with microsensors within the brain and subcutaneous ("body") tissue. Blood lactate was measured after asphyxia. RESULTS Brain and body PO2 fell to apparent zero with little recovery during 5% O2 asphyxia and 5% or 9% O2 hypoxia, and increased more than twofold during 20% CO2 hypercapnia. Unlike body PO2 , brain PO2 recovered rapidly to control after a transient fall (rat), or was slightly higher than control (guinea pig) during 9% O2 asphyxia. Asphyxia (5% O2 ) induced a respiratory acidosis paralleled by a progressive metabolic (lact)acidosis that was much smaller within than outside the brain. Hypoxia (5% O2 ) produced a brain-confined alkalosis. Hypercapnia outlasting asphyxia suppressed pH recovery and prolonged the post-asphyxia PO2 overshoot. All pH changes were accompanied by consistent shifts in the blood-brain barrier potential. CONCLUSION Regardless of brain maturation stage, hypercapnia can restore brain PO2 and protect the brain against metabolic acidosis despite compromised oxygen availability during asphyxia. This effect extends to the recovery phase if normocapnia is restored slowly, and it is absent during hypoxia, demonstrating that exposure to hypoxia does not mimic asphyxia.
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Affiliation(s)
- Alexey S. Pospelov
- Faculty of Biological and Environmental Sciences, Molecular and Integrative Biosciences University of Helsinki Helsinki Finland
| | - Martin Puskarjov
- Faculty of Biological and Environmental Sciences, Molecular and Integrative Biosciences University of Helsinki Helsinki Finland
| | - Kai Kaila
- Faculty of Biological and Environmental Sciences, Molecular and Integrative Biosciences University of Helsinki Helsinki Finland
- Neuroscience Center (HiLIFE) University of Helsinki Helsinki Finland
| | - Juha Voipio
- Faculty of Biological and Environmental Sciences, Molecular and Integrative Biosciences University of Helsinki Helsinki Finland
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11
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Wagley PK, Williamson J, Skwarzynska D, Kapur J, Burnsed J. Continuous Video Electroencephalogram during Hypoxia-Ischemia in Neonatal Mice. J Vis Exp 2020. [PMID: 32597865 DOI: 10.3791/61346] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Hypoxia ischemia is the most common cause of neonatal seizures. Animal models are crucial for understanding the mechanisms and physiology underlying neonatal seizures and hypoxia ischemia. This manuscript describes a method for continuous video electroencephalogram (EEG) monitoring in neonatal mice to detect seizures and analyze EEG background during hypoxia ischemia. Use of video and EEG in conjunction allows description of seizure semiology and confirmation of seizures. This method also allows analysis of power spectrograms and EEG background pattern trends over the experimental time period. In this hypoxia ischemia model, the method allows EEG recording prior to injury to obtain a normative baseline and during injury and recovery. Total monitoring time is limited by the inability to separate pups from the mother for longer than four hours. Although, we have used a model of hypoxic-ischemic seizures in this manuscript, this method for neonatal video EEG monitoring could be applied to diverse disease and seizure models in rodents.
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Affiliation(s)
- Pravin K Wagley
- Department of Pediatrics, University of Virginia; Department of Neurology, University of Virginia
| | | | | | - Jaideep Kapur
- Department of Neurology, University of Virginia; Brain Institute, University of Virginia; Department of Neuroscience, University of Virginia
| | - Jennifer Burnsed
- Department of Pediatrics, University of Virginia; Department of Neurology, University of Virginia;
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12
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Tang W, Xin X, O'Connor M, Zhang N, Lai B, Man HY, Xie Y, Wei Y. Transient sublethal hypoxia in neonatal rats causes reduced dendritic spines, aberrant synaptic plasticity, and impairments in memory. J Neurosci Res 2020; 98:1588-1604. [PMID: 32495348 DOI: 10.1002/jnr.24652] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2019] [Revised: 05/08/2020] [Accepted: 05/10/2020] [Indexed: 01/06/2023]
Abstract
Hypoxic/ischemic insult, a leading cause of functional brain defects, has been extensively studied in both clinical and experimental animal research, including its etiology, neuropathogenesis, and pharmacological interventions. Transient sublethal hypoxia (TSH) is a common clinical occurrence in the perinatal period. However, its effect on early developing brains remains poorly understood. The present study was designed to investigate the effect of TSH on the dendrite and dendritic spine formation, neuronal and synaptic activity, and cognitive behavior of early postnatal Day 1 rat pups. While TSH showed no obvious effect on gross brain morphology, neuron cell density, or glial activation in the hippocampus, we found transient hypoxia did cause significant changes in neuronal structure and function. In brains exposed to TSH, hippocampal neurons developed shorter and thinner dendrites, with decreased dendritic spine density, and reduced strength in excitatory synaptic transmission. Moreover, TSH-treated rats showed impaired cognitive performance in spatial learning and memory. Our findings demonstrate that TSH in newborn rats can cause significant impairments in synaptic formation and function, and long-lasting brain functional deficits. Therefore, this study provides a useful animal model for the study of TSH on early developing brains and to explore potential pharmaceutical interventions for patients subjected to TSH insult.
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Affiliation(s)
- Wenjie Tang
- Research Center for Translational Medicine & Key Laboratory of Arrhythmias of the Ministry of Education of China, Shanghai East Hospital, Tongji University School of Medicine, Shanghai, China
| | - Xiaoming Xin
- Shanghai University of Medicine and Health Sciences, Shanghai, China
| | | | - Nana Zhang
- Research Center for Translational Medicine & Key Laboratory of Arrhythmias of the Ministry of Education of China, Shanghai East Hospital, Tongji University School of Medicine, Shanghai, China
| | - Bin Lai
- Institute of Brain science, Fudan University, Shanghai, China
| | - Heng-Ye Man
- Department of Biology, Boston University, Boston, MA, USA
| | - Yuanyun Xie
- National Clinic and Medicine Research Institute for Geriatric Diseases, Gannan Health Promotion and Translational Laboratory, The First Affiliated Hospital, Gannan University of Medical sciences, Ganzhou, China
| | - Youzhen Wei
- Research Center for Translational Medicine & Key Laboratory of Arrhythmias of the Ministry of Education of China, Shanghai East Hospital, Tongji University School of Medicine, Shanghai, China
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13
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Patel PA, Liang C, Arora A, Vijayan S, Ahuja S, Wagley PK, Settlage R, LaConte LEW, Goodkin HP, Lazar I, Srivastava S, Mukherjee K. Haploinsufficiency of X-linked intellectual disability gene CASK induces post-transcriptional changes in synaptic and cellular metabolic pathways. Exp Neurol 2020; 329:113319. [PMID: 32305418 DOI: 10.1016/j.expneurol.2020.113319] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2019] [Revised: 04/04/2020] [Accepted: 04/15/2020] [Indexed: 12/17/2022]
Abstract
Heterozygous mutations in the X-linked gene CASK are associated with intellectual disability, microcephaly, pontocerebellar hypoplasia, optic nerve hypoplasia and partially penetrant seizures in girls. The Cask+/- heterozygous knockout female mouse phenocopies the human disorder and exhibits postnatal microencephaly, cerebellar hypoplasia and optic nerve hypoplasia. It is not known if Cask+/- mice also display seizures, nor is known the molecular mechanism by which CASK haploinsufficiency produces the numerous documented phenotypes. 24-h video electroencephalography demonstrates that despite sporadic seizure activity, the overall electrographic patterns remain unaltered in Cask+/- mice. Additionally, seizure threshold to the commonly used kindling agent, pentylenetetrazol, remains unaltered in Cask+/- mice, indicating that even in mice the seizure phenotype is only partially penetrant and may have an indirect mechanism. RNA sequencing experiments on Cask+/- mouse brain uncovers a very limited number of changes, with most differences arising in the transcripts of extracellular matrix proteins and the transcripts of a group of nuclear proteins. In contrast to limited changes at the transcript level, quantitative whole-brain proteomics using iTRAQ quantitative mass-spectrometry reveals major changes in synaptic, metabolic/mitochondrial, cytoskeletal, and protein metabolic pathways. Unbiased protein-protein interaction mapping using affinity chromatography demonstrates that CASK may form complexes with proteins belonging to the same functional groups in which altered protein levels are observed. We discuss the mechanism of the observed changes in the context of known molecular function/s of CASK. Overall, our data indicate that the phenotypic spectrum of female Cask+/- mice includes sporadic seizures and thus closely parallels that of CASK haploinsufficient girls; the Cask+/- mouse is thus a face-validated model for CASK-related pathologies. We therefore surmise that CASK haploinsufficiency is likely to affect brain structure and function due to dysregulation of several cellular pathways including synaptic signaling and cellular metabolism.
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Affiliation(s)
- P A Patel
- Center for Neurobiology Research, Fralin Biomedical Research Institute at Virginia Tech Carilion, Roanoke, VA, United States; Graduate Program in Translational Biology, Medicine, and Health, Virginia Tech, Blacksburg, VA, United States
| | - C Liang
- Center for Neurobiology Research, Fralin Biomedical Research Institute at Virginia Tech Carilion, Roanoke, VA, United States
| | - A Arora
- Center for Neurobiology Research, Fralin Biomedical Research Institute at Virginia Tech Carilion, Roanoke, VA, United States
| | - S Vijayan
- School of Neuroscience, Virginia Tech, Blacksburg, VA, United States
| | - S Ahuja
- Biological Sciences, Virginia Tech, Blacksburg, VA, United States
| | - P K Wagley
- Neurology, University of Virginia, Charlottesville, VA, USA
| | - R Settlage
- Advanced Research Computing, Virginia Tech, Blacksburg, VA, United States
| | - L E W LaConte
- Fralin Biomedical Research Institute at Virginia Tech Carilion, Roanoke, VA, United States
| | - H P Goodkin
- Neurology, University of Virginia, Charlottesville, VA, USA
| | - I Lazar
- Biological Sciences, Virginia Tech, Blacksburg, VA, United States
| | - S Srivastava
- Fralin Biomedical Research Institute at Virginia Tech Carilion, Roanoke, VA, United States
| | - K Mukherjee
- Center for Neurobiology Research, Fralin Biomedical Research Institute at Virginia Tech Carilion, Roanoke, VA, United States; Fralin Biomedical Research Institute at Virginia Tech Carilion, Roanoke, VA, United States; Department of Psychiatry and Behavioral Medicine, Virginia Tech Carilion School of Medicine, Roanoke, VA, United States.
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14
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Grosenbaugh DK, Joshi S, Fitzgerald MP, Lee KS, Wagley PK, Koeppel AF, Turner SD, McConnell MJ, Goodkin HP. A deletion in Eml1 leads to bilateral subcortical heterotopia in the tish rat. Neurobiol Dis 2020; 140:104836. [PMID: 32179177 PMCID: PMC7814471 DOI: 10.1016/j.nbd.2020.104836] [Citation(s) in RCA: 2] [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: 01/17/2019] [Revised: 03/11/2020] [Accepted: 03/12/2020] [Indexed: 12/13/2022] Open
Abstract
Children with malformations of cortical development (MCD) are at risk for epilepsy, developmental delays, behavioral disorders, and intellectual disabilities. For a subset of these children, antiseizure medications or epilepsy surgery may result in seizure freedom. However, there are limited options for treating or curing the other conditions, and epilepsy surgery is not an option in all cases of pharmacoresistant epilepsy. Understanding the genetic and neurobiological mechanisms underlying MCD is a necessary step in elucidating novel therapeutic targets. The tish (telencephalic internal structural heterotopia) rat is a unique model of MCD with spontaneous seizures, but the underlying genetic mutation(s) have remained unknown. DNA and RNA-sequencing revealed that a deletion encompassing a previously unannotated first exon markedly diminished Eml1 transcript and protein abundance in the tish brain. Developmental electrographic characterization of the tish rat revealed early-onset of spontaneous spike-wave discharge (SWD) bursts beginning at postnatal day (P) 17. A dihybrid cross demonstrated that the mutant Eml1 allele segregates with the observed dysplastic cortex and the early-onset SWD bursts in monogenic autosomal recessive frequencies. Our data link the development of the bilateral, heterotopic dysplastic cortex of the tish rat to a deletion in Eml1.
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Affiliation(s)
- Denise K Grosenbaugh
- Department of Neurology, University of Virginia School of Medicine, Charlottesville, VA, United States
| | - Suchitra Joshi
- Department of Neurology, University of Virginia School of Medicine, Charlottesville, VA, United States
| | - Mark P Fitzgerald
- Department of Neuroscience, University of Virginia School of Medicine, Charlottesville, VA, United States
| | - Kevin S Lee
- Department of Neuroscience, University of Virginia School of Medicine, Charlottesville, VA, United States; Department of Neurosurgery, University of Virginia School of Medicine, Charlottesville, VA, United States; Center for Brain Immunology and Glia, University of Virginia School of Medicine, Charlottesville, VA, United States
| | - Pravin K Wagley
- Department of Neurology, University of Virginia School of Medicine, Charlottesville, VA, United States
| | - Alexander F Koeppel
- Center for Public Health Sciences, University of Virginia School of Medicine, Charlottesville, VA, United States
| | - Stephen D Turner
- Center for Public Health Sciences, University of Virginia School of Medicine, Charlottesville, VA, United States
| | - Michael J McConnell
- Department of Biochemistry and Molecular Genetics, University of Virginia School of Medicine, Charlottesville, VA, United States; Department of Neuroscience, University of Virginia School of Medicine, Charlottesville, VA, United States; Center for Brain Immunology and Glia, University of Virginia School of Medicine, Charlottesville, VA, United States; Center for Public Health Genomics, University of Virginia School of Medicine, Charlottesville, VA, United States.
| | - Howard P Goodkin
- Department of Neurology, University of Virginia School of Medicine, Charlottesville, VA, United States; Department of Pediatrics, University of Virginia School of Medicine, Charlottesville, VA, United States.
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15
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Burnsed J, Skwarzyńska D, Wagley PK, Isbell L, Kapur J. Neuronal Circuit Activity during Neonatal Hypoxic-Ischemic Seizures in Mice. Ann Neurol 2019; 86:927-938. [PMID: 31509619 DOI: 10.1002/ana.25601] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2019] [Revised: 09/09/2019] [Accepted: 09/09/2019] [Indexed: 12/19/2022]
Abstract
OBJECTIVE To identify circuits active during neonatal hypoxic-ischemic (HI) seizures and seizure propagation using electroencephalography (EEG), behavior, and whole-brain neuronal activity mapping. METHODS Mice were exposed to HI on postnatal day 10 using unilateral carotid ligation and global hypoxia. EEG and video were recorded for the duration of the experiment. Using immediate early gene reporter mice, active cells expressing cfos were permanently tagged with reporter protein tdTomato during a 90-minute window. After 1 week, allowing maximal expression of the reporter protein, whole brains were processed, lipid cleared, and imaged with confocal microscopy. Whole-brain reconstruction and analysis of active neurons (colocalized tdTomato/NeuN) were performed. RESULTS HI resulted in seizure behaviors that were bilateral or unilateral tonic-clonic and nonconvulsive in this model. Mice exhibited characteristic EEG background patterns such as burst suppression and suppression. Neuronal activity mapping revealed bilateral motor cortex and unilateral, ischemic somatosensory cortex, lateral thalamus, and hippocampal circuit activation. Immunohistochemical analysis revealed regional differences in myelination, which coincide with these activity patterns. Astrocytes and blood vessel endothelial cells also expressed cfos during HI. INTERPRETATION Using a combination of EEG, seizure semiology analysis, and whole-brain neuronal activity mapping, we suggest that this rodent model of neonatal HI results in EEG patterns similar to those observed in human neonates. Activation patterns revealed in this study help explain complex seizure behaviors and EEG patterns observed in neonatal HI injury. This pattern may be, in part, secondary to regional differences in development in the neonatal brain. ANN NEUROL 2019;86:927-938.
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Affiliation(s)
- Jennifer Burnsed
- Department of Pediatrics, University of Virginia, Charlottesville, VA.,Department of Neurology, University of Virginia, Charlottesville, VA
| | - Daria Skwarzyńska
- Department of Pediatrics, University of Virginia, Charlottesville, VA
| | - Pravin K Wagley
- Department of Pediatrics, University of Virginia, Charlottesville, VA
| | - Laura Isbell
- College of Arts and Sciences, University of Virginia, Charlottesville, VA
| | - Jaideep Kapur
- Department of Neurology, University of Virginia, Charlottesville, VA.,University of Virginia Brain Institute, University of Virginia, Charlottesville, VA.,Department of Neuroscience, University of Virginia, Charlottesville, VA
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16
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Torres-Cuevas I, Corral-Debrinski M, Gressens P. Brain oxidative damage in murine models of neonatal hypoxia/ischemia and reoxygenation. Free Radic Biol Med 2019; 142:3-15. [PMID: 31226400 DOI: 10.1016/j.freeradbiomed.2019.06.011] [Citation(s) in RCA: 54] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/19/2019] [Revised: 05/26/2019] [Accepted: 06/10/2019] [Indexed: 02/08/2023]
Abstract
The brain is one of the main organs affected by hypoxia and reoxygenation in the neonatal period and one of the most vulnerable to oxidative stress. Hypoxia/ischemia and reoxygenation leads to impairment of neurogenesis, disruption of cortical migration, mitochondrial damage and neuroinflammation. The extent of the injury depends on the clinical manifestation in the affected regions. Preterm newborns are highly vulnerable, and they exhibit severe clinical manifestations such as intraventricular hemorrhage (IVH), retinopathy of prematurity (ROP) and diffuse white matter injury (DWMI) among others. In the neonatal period, the accumulation of high levels of reactive oxygen species exacerbated by the immature antioxidant defense systems in represents cellular threats that, if they exceed or bypass physiological counteracting mechanisms, are responsible of significant neuronal damage. Several experimental models in mice mimic the consequences of perinatal asphyxia and the use of oxygen in the reanimation process that produce brain injury. The aim of this review is to highlight brain damage associated with oxidative stress in different murine models of hypoxia/ischemia and reoxygenation.
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Affiliation(s)
| | | | - Pierre Gressens
- INSERM UMR1141, Université Paris Diderot, Sorbonne Paris Cité, Paris, France
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17
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Bunton-Stasyshyn RKA, Wagnon JL, Wengert ER, Barker BS, Faulkner A, Wagley PK, Bhatia K, Jones JM, Maniaci MR, Parent JM, Goodkin HP, Patel MK, Meisler MH. Prominent role of forebrain excitatory neurons in SCN8A encephalopathy. Brain 2019; 142:362-375. [PMID: 30601941 DOI: 10.1093/brain/awy324] [Citation(s) in RCA: 60] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2018] [Accepted: 10/29/2018] [Indexed: 12/25/2022] Open
Abstract
De novo mutations of the sodium channel gene SCN8A result in an epileptic encephalopathy with refractory seizures, developmental delay, and elevated risk of sudden death. p.Arg1872Trp is a recurrent de novo SCN8A mutation reported in 14 unrelated individuals with epileptic encephalopathy that included seizure onset in the prenatal or infantile period and severe verbal and ambulatory comorbidities. The major biophysical effect of the mutation was previously shown to be impaired channel inactivation accompanied by increased current density. We have generated a conditional mouse mutation in which expression of this severe gain-of-function mutation is dependent upon Cre recombinase. Global activation of p.Arg1872Trp by EIIa-Cre resulted in convulsive seizures and lethality at 2 weeks of age. Neural activation of the p.Arg1872Trp mutation by Nestin-Cre also resulted in early onset seizures and death. Restriction of p.Arg1872Trp expression to excitatory neurons using Emx1-Cre recapitulated seizures and juvenile lethality between 1 and 2 months of age. In contrast, activation of p.Arg1872Trp in inhibitory neurons by Gad2-Cre or Dlx5/6-Cre did not induce seizures or overt neurological dysfunction. The sodium channel modulator GS967/Prax330 prolonged survival of mice with global expression of R1872W and also modulated the activity of the mutant channel in transfected cells. Activation of the p.Arg1872Trp mutation in adult mice was sufficient to generate seizures and death, indicating that successful therapy will require lifelong treatment. These findings provide insight into the pathogenic mechanism of this gain-of-function mutation of SCN8A and identify excitatory neurons as critical targets for therapeutic intervention.
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Affiliation(s)
| | - Jacy L Wagnon
- Department of Human Genetics, University of Michigan, Ann Arbor, MI, USA
| | - Eric R Wengert
- Department of Anesthesiology, University of Virginia, Charlottesville VA, USA.,Neuroscience Graduate Program, University of Virginia, Charlottesville VA, USA
| | - Bryan S Barker
- Department of Anesthesiology, University of Virginia, Charlottesville VA, USA.,Neuroscience Graduate Program, University of Virginia, Charlottesville VA, USA
| | - Alexa Faulkner
- Neuroscience Graduate Program, University of Michigan, Ann Arbor, MI, USA
| | - Pravin K Wagley
- Department of Neurology, University of Virginia, Charlottesville VA, USA
| | - Kritika Bhatia
- Department of Neurology, University of Michigan, Ann Arbor, MI, USA
| | - Julie M Jones
- Department of Human Genetics, University of Michigan, Ann Arbor, MI, USA
| | - Marissa R Maniaci
- Department of Human Genetics, University of Michigan, Ann Arbor, MI, USA
| | - Jack M Parent
- Neuroscience Graduate Program, University of Michigan, Ann Arbor, MI, USA.,Department of Neurology, University of Michigan, Ann Arbor, MI, USA
| | - Howard P Goodkin
- Neuroscience Graduate Program, University of Virginia, Charlottesville VA, USA.,Department of Neurology, University of Virginia, Charlottesville VA, USA
| | - Manoj K Patel
- Department of Anesthesiology, University of Virginia, Charlottesville VA, USA.,Neuroscience Graduate Program, University of Virginia, Charlottesville VA, USA
| | - Miriam H Meisler
- Department of Human Genetics, University of Michigan, Ann Arbor, MI, USA.,Department of Neurology, University of Michigan, Ann Arbor, MI, USA
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18
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Rensing N, Moy B, Friedman JL, Galindo R, Wong M. Longitudinal analysis of developmental changes in electroencephalography patterns and sleep-wake states of the neonatal mouse. PLoS One 2018; 13:e0207031. [PMID: 30399187 PMCID: PMC6219806 DOI: 10.1371/journal.pone.0207031] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2018] [Accepted: 10/23/2018] [Indexed: 11/19/2022] Open
Abstract
The neonatal brain undergoes rapid maturational changes that facilitate the normal development of the nervous system and also affect the pathological response to brain injury. Electroencephalography (EEG) and analysis of sleep-wake vigilance states provide important insights into the function of the normal and diseased immature brain. While developmental changes in EEG and vigilance states are well-described in people, less is known about the normal maturational properties of rodent EEG, including the emergence and evolution of sleep-awake vigilance states. In particular, a number of developmental EEG studies have been performed in rats, but there is limited comparable research in neonatal mice, especially as it pertains to longitudinal EEG studies performed within the same mouse. In this study, we have attempted to provide a relatively comprehensive assessment of developmental changes in EEG background activity and vigilance states in wild-type mice from postnatal days 9-21. A novel EEG and EMG method allowed serial recording from the same mouse pups. EEG continuity and power and vigilance states were analyzed by quantitative assessment and fast Fourier transforms. During this developmental period, we demonstrate the timing of maturational changes in EEG background continuity, frequencies, and power and the emergence of identifiable wake, NREM, and REM sleep states. These results should serve as important control data for physiological studies of mouse models of normal brain development and neurological disease.
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Affiliation(s)
- Nicholas Rensing
- Department of Neurology and the Hope Center for Neurological Disorders, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Brianna Moy
- Department of Neurology and the Hope Center for Neurological Disorders, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Joseph L. Friedman
- Department of Neurology and the Hope Center for Neurological Disorders, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Rafael Galindo
- Department of Neurology and the Hope Center for Neurological Disorders, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Michael Wong
- Department of Neurology and the Hope Center for Neurological Disorders, Washington University School of Medicine, St. Louis, Missouri, United States of America
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19
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Akman O, Raol YH, Auvin S, Cortez MA, Kubova H, de Curtis M, Ikeda A, Dudek FE, Galanopoulou AS. Methodologic recommendations and possible interpretations of video-EEG recordings in immature rodents used as experimental controls: A TASK1-WG2 report of the ILAE/AES Joint Translational Task Force. Epilepsia Open 2018; 3:437-459. [PMID: 30525114 PMCID: PMC6276777 DOI: 10.1002/epi4.12262] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/14/2018] [Indexed: 01/30/2023] Open
Abstract
The use of immature rodents to study physiologic aspects of cortical development requires high‐quality recordings electroencephalography (EEG) with simultaneous video recording (vEEG) of behavior. Normative developmental vEEG data in control animals are fundamental for the study of abnormal background activity in animal models of seizures or other neurologic disorders. Electrical recordings from immature, freely behaving rodents can be particularly difficult because of the small size of immature rodents, their thin and soft skull, interference with the recording apparatus by the dam, and other technical challenges. In this report of the TASK1 Working Group 2 (WG2) of the International League Against Epilepsy/American Epilepsy Society (ILAE/AES) Joint Translational Task Force, we provide suggestions that aim to optimize future vEEG recordings from immature rodents, as well as their interpretation. We focus on recordings from immature rodents younger than 30 days old used as experimental controls, because the quality and correct interpretation of such recordings is important when interpreting the vEEG results of animals serving as models of neurologic disorders. We discuss the technical aspects of such recordings and compare tethered versus wireless approaches. We also summarize the appearance of common artifacts and various patterns of electrical activity seen in young rodents used as controls as a function of behavioral state, age, and (where known) sex and strain. The information herein will hopefully help improve the methodology of vEEG recordings from immature rodents and may lead to results and interpretations that are more consistent across studies from different laboratories.
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Affiliation(s)
- Ozlem Akman
- Department of Physiology Faculty of Medicine Istanbul Bilim University Istanbul Turkey
| | - Yogendra H Raol
- Division of Neurology Department of Pediatrics School of Medicine Translational Epilepsy Research Program University of Colorado Aurora Colorado U.S.A
| | - Stéphane Auvin
- PROTECT, INSERM UMR1141 APHP University Paris Diderot Sorbonne Paris Cité Paris France.,University Hospital Robert-Debré Service of Pediatric Neurology Paris France
| | - Miguel A Cortez
- Department of Pediatrics University of Toronto Toronto Ontario Canada.,Program of Neurosciences and Mental Health Peter Gilgan Center for Research and Learning SickKids Research Institute Toronto Ontario Canada.,Division of Neurology The Hospital for Sick Children Toronto Ontario Canada
| | - Hana Kubova
- Department of Developmental Epileptology Institute of the Czech Academy of Sciences Czech Academy of Sciences Prague Czech Republic
| | - Marco de Curtis
- Epilepsy Unit Carlo Besta Neurological Institute Foundation Milan Italy
| | - Akio Ikeda
- Department of Epilepsy, Movement Disorders, and Physiology Kyoto University Graduate School of Medicine Kyoto Japan
| | - F Edward Dudek
- Department of Neurosurgery University of Utah School of Medicine Salt Lake City Utah U.S.A
| | - Aristea S Galanopoulou
- Laboratory of Developmental Epilepsy Saul R. Korey Department of Neurology Dominick P. Purpura Department of Neuroscience Isabelle Rapin Division of Child Neurology Albert Einstein College of Medicine Einstein/Montefiore Epilepsy Center Montefiore Medical Center Bronx New York U.S.A
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20
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Grosenbaugh DK, Ross BM, Wagley P, Zanelli SA. The Role of Kainate Receptors in the Pathophysiology of Hypoxia-Induced Seizures in the Neonatal Mouse. Sci Rep 2018; 8:7035. [PMID: 29728616 PMCID: PMC5935682 DOI: 10.1038/s41598-018-24722-3] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2018] [Accepted: 04/09/2018] [Indexed: 12/30/2022] Open
Abstract
Kainate receptors (KARs) are glutamate receptors with peak expression during late embryonic and early postnatal periods. Altered KAR-mediated neurotransmission and subunit expression are observed in several brain disorders, including epilepsy. Here, we examined the role of KARs in regulating seizures in neonatal C57BL/6 mice exposed to a hypoxic insult. We found that knockout of the GluK2 subunit, or blockade of KARs by UBP310 reduced seizure susceptibility during the period of reoxygenation. Following the hypoxic insult, we observed an increase in excitatory neurotransmission in hippocampal CA3 pyramidal cells, which was blocked by treatment with UBP310 prior to hypoxia. Similarly, we observed increased excitatory neurotransmission in CA3 pyramidal cells in an in vitro hippocampal slice model of hypoxic-ischemia. This increase was absent in slices from GluK2−/− mice and in slices treated with UBP310, suggesting that KARs regulate, at least in part, excitatory synaptic neurotransmission following in vivo hypoxia in neonatal mice. Data from these hypoxia models demonstrate that KARs, specifically those containing the GluK2 subunit, contribute to alterations in excitatory neurotransmission and seizure susceptibility, particularly during the reoxygenation period, in neonatal mice. Therapies targeting KARs may prove successful in treatment of neonates affected by hypoxic seizures.
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Affiliation(s)
- Denise K Grosenbaugh
- Department of Neurology, University of Virginia, Charlottesville, Virginia, 22908, USA
| | - Brittany M Ross
- Department of Pediatrics, University of Virginia, Charlottesville, Virginia, 22908, USA
| | - Pravin Wagley
- Department of Neurology, University of Virginia, Charlottesville, Virginia, 22908, USA
| | - Santina A Zanelli
- Department of Pediatrics, University of Virginia, Charlottesville, Virginia, 22908, USA.
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21
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Dingman AL, Stence NV, O'Neill BR, Sillau SH, Chapman KE. Seizure Severity Is Correlated With Severity of Hypoxic-Ischemic Injury in Abusive Head Trauma. Pediatr Neurol 2018; 82:29-35. [PMID: 29625848 DOI: 10.1016/j.pediatrneurol.2017.12.003] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/08/2017] [Accepted: 12/04/2017] [Indexed: 10/18/2022]
Abstract
BACKGROUND The objective of this study was to characterize hypoxic-ischemic injury and seizures in abusive head trauma. METHODS We studied 58 children with moderate or severe traumatic brain injury due to abusive head trauma. Continuous electroencephalograms and magnetic resonance images were scored. RESULTS Electrographic seizures (51.2%) and hypoxic-ischemic injury (77.4%) were common in our cohort. Younger age was associated with electrographic seizures (no seizures: median age 13.5 months, interquartile range five to 25 months, versus seizures: 4.5 months, interquartile range 3 to 9.5 months; P = 0.001). Severity of hypoxic-ischemic injury was also associated with seizures (no seizures: median injury score 1.0, interquartile range 0 to 3, versus seizures: 4.5, interquartile range 3 to 8; P = 0.01), but traumatic injury severity was not associated with seizures (no seizures: mean injury score 3.78 ± 1.68 versus seizures: mean injury score 3.83 ± 0.95, P = 0.89). There was a correlation between hypoxic-ischemic injury severity and seizure burden when controlling for patient age (rs=0.61, P < 0.001). The ratio of restricted diffusion volume to total brain volume (restricted diffusion ratio) was smaller on magnetic resonance imaging done early (median restricted diffusion ratio 0.03, interquartile range 0 to 0.23 on magnetic resonance imaging done within two days versus median restricted diffusion ratio 0.13, interquartile range 0.01 to 0.43 on magnetic resonance imaging done after two days, P = 0.03). CONCLUSIONS Electrographic seizures are common in children with moderate to severe traumatic brain injury from abusive head trauma, and therefore children with suspected abusive head trauma should be monitored with continuous electroencephalogram. Severity of hypoxic-ischemic brain injury is correlated with severity of seizures, and evidence of hypoxic-ischemic injury on magnetic resonance imaging may evolve over time. Therefore children with a high seizure burden should be reimaged to evaluate for evolving hypoxic-ischemic injury.
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Affiliation(s)
- Andra L Dingman
- Department of Pediatrics, Division of Child Neurology, University of Colorado Anschuts Medical Campus, Aurora, Colorado.
| | - Nicholas V Stence
- Department of Radiology, Division of Pediatric Radiology, University of Colorado Anschuts Medical Campus, Aurora, Colorado
| | - Brent R O'Neill
- Department of Neurosurgery, Division of Pediatric Neurosurgery, University of Colorado Anschuts Medical Campus, Aurora, Colorado
| | - Stefan H Sillau
- Department of Neurology, University of Colorado Anschuts Medical Campus, Aurora, Colorado
| | - Kevin E Chapman
- Department of Pediatrics, Division of Child Neurology, University of Colorado Anschuts Medical Campus, Aurora, Colorado
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Millar LJ, Shi L, Hoerder-Suabedissen A, Molnár Z. Neonatal Hypoxia Ischaemia: Mechanisms, Models, and Therapeutic Challenges. Front Cell Neurosci 2017; 11:78. [PMID: 28533743 PMCID: PMC5420571 DOI: 10.3389/fncel.2017.00078] [Citation(s) in RCA: 213] [Impact Index Per Article: 30.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2016] [Accepted: 03/07/2017] [Indexed: 12/11/2022] Open
Abstract
Neonatal hypoxia-ischaemia (HI) is the most common cause of death and disability in human neonates, and is often associated with persistent motor, sensory, and cognitive impairment. Improved intensive care technology has increased survival without preventing neurological disorder, increasing morbidity throughout the adult population. Early preventative or neuroprotective interventions have the potential to rescue brain development in neonates, yet only one therapeutic intervention is currently licensed for use in developed countries. Recent investigations of the transient cortical layer known as subplate, especially regarding subplate's secretory role, opens up a novel set of potential molecular modulators of neonatal HI injury. This review examines the biological mechanisms of human neonatal HI, discusses evidence for the relevance of subplate-secreted molecules to this condition, and evaluates available animal models. Neuroserpin, a neuronally released neuroprotective factor, is discussed as a case study for developing new potential pharmacological interventions for use post-ischaemic injury.
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Affiliation(s)
- Lancelot J. Millar
- Molnár Group, Department of Physiology, Anatomy and Genetics, University of OxfordOxford, UK
| | - Lei Shi
- Molnár Group, Department of Physiology, Anatomy and Genetics, University of OxfordOxford, UK
- JNU-HKUST Joint Laboratory for Neuroscience and Innovative Drug Research, College of Pharmacy, Jinan UniversityGuangzhou, China
| | | | - Zoltán Molnár
- Molnár Group, Department of Physiology, Anatomy and Genetics, University of OxfordOxford, UK
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Neonatal seizures induced by pentylenetetrazol or kainic acid disrupt primary cilia growth on developing mouse cortical neurons. Exp Neurol 2016; 282:119-27. [PMID: 27181411 DOI: 10.1016/j.expneurol.2016.05.015] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2015] [Revised: 04/19/2016] [Accepted: 05/11/2016] [Indexed: 11/23/2022]
Abstract
Neonatal or early-life seizures (ELS) are often associated with life-long neurophysiological, cognitive and behavioral deficits, but the underlying mechanisms contributing to these deficits remain poorly understood. Newborn, post-migratory cortical neurons sprout ciliary buds (procilia) that mature into primary cilia. Disruption of the growth or signaling capabilities of these cilia has been linked to atypical neurite outgrowth from neurons and abnormalities in neuronal circuitry. Here, we tested the hypothesis that generalized seizures induced by pentylenetetrazol (PTZ) or kainic acid (KA) during early postnatal development impair neuronal and/or glial ciliogenesis. Mice received PTZ (50 or 100mg/kg), KA (2mg/kg), or saline either once at birth (P0), or once daily from P0 to P4. Using immunohistochemistry and electron microscopy, the cilia of neurons and glia were examined at P7, P14, and P42. A total of 83 regions were analyzed, representing 13 unique neocortical and hippocampal regions. Neuronal cilia were identified by co-expression of NeuN and type 3 adenylyl cyclase (ACIII) or somatostatin receptor 3 (SSTR3), while glial cilia were identified by co-expression of GFAP, Arl13b, and gamma-tubulin. We found that PTZ exposure at either P0 or from P0 to P4 induced convulsive behavior, followed by acute and lasting effects on neuronal cilia lengths that varied depending on the cortical region, PTZ dose, injection frequency, and time post-PTZ. Both increases and decreases in neuronal cilia length were observed. No changes in the length of glial cilia were observed under any of the test conditions. Lastly, we found that a single KA seizure at P0 led to similar abnormalities in neuronal cilia lengths. Our results suggest that seizure(s) occurring during early stages of cortical development induce persistent and widespread changes in neuronal cilia length. Given the impact neuronal cilia have on neuronal differentiation, ELS-induced changes in ciliogenesis may contribute to long-term pathology and abnormal cortical function.
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Shi XY, Yang XF, Tomonoh Y, Hu LY, Ju J, Hirose S, Zou LP. Development of a mouse model of infantile spasms induced by N -methyl- d -aspartate. Epilepsy Res 2015; 118:29-33. [DOI: 10.1016/j.eplepsyres.2015.09.014] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2015] [Revised: 04/28/2015] [Accepted: 09/22/2015] [Indexed: 01/31/2023]
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Sun H, Juul HM, Jensen FE. Models of hypoxia and ischemia-induced seizures. J Neurosci Methods 2015; 260:252-60. [PMID: 26434705 DOI: 10.1016/j.jneumeth.2015.09.023] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2015] [Accepted: 09/22/2015] [Indexed: 01/19/2023]
Abstract
Despite greater understanding and improved management, seizures continue to be a major problem in childhood. Neonatal seizures are often refractory to conventional antiepileptic drugs, and can result in later life epilepsy and cognitive deficits, conditions for which there are no specific treatments. Hypoxic and/or ischemic encephalopathy (HIE) is the most common cause for neonatal seizures, and accounts for more than two-thirds of neonatal seizure cases. A better understanding of the cellular and molecular mechanisms is essential for identifying new therapeutic strategies that control the neonatal seizures and its cognitive consequences. This heavily relies on animal models that play a critical role in discovering novel mechanisms underlying both epileptogenesis and associated cognitive impairments. To date, a number of animal models have provided a tremendous amount of information regarding the pathophysiology of HIE-induced neonatal seizures. This review provides an overview on the most important features of the main animal models of HIE-induced seizures. In particular, we focus on the methodology of seizure induction and the characterizations of post-HIE injury consequences. These aspects of HIE-induced seizure models are discussed in the light of the suitability of these models in studying human HIE-induced seizures.
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Affiliation(s)
- Hongyu Sun
- Department of Neurology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
| | - Halvor M Juul
- Department of Neurology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
| | - Frances E Jensen
- Department of Neurology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States.
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Zayachkivsky A, Lehmkuhle MJ, Ekstrand JJ, Dudek FE. Ischemic injury suppresses hypoxia-induced electrographic seizures and the background EEG in a rat model of perinatal hypoxic-ischemic encephalopathy. J Neurophysiol 2015; 114:2753-63. [PMID: 26354320 DOI: 10.1152/jn.00796.2014] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2014] [Accepted: 09/05/2015] [Indexed: 12/16/2022] Open
Abstract
The relationship among neonatal seizures, abnormalities of the electroencephalogram (EEG), brain injury, and long-term neurological outcome (e.g., epilepsy) remains controversial. The effects of hypoxia alone (Ha) and hypoxia-ischemia (HI) were studied in neonatal rats at postnatal day 7; both models generate EEG seizures during the 2-h hypoxia treatment, but only HI causes an infarct with severe neuronal degeneration. Single-channel, differential recordings of acute EEG seizures and background suppression were recorded with a novel miniature telemetry device during the hypoxia treatment and analyzed quantitatively. The waveforms of electrographic seizures (and their behavioral correlates) appeared virtually identical in both models and were identified as discrete events with high power in the traditional delta (0.1-4 Hz) and/or alpha (8-12 Hz) bands. Although the EEG patterns during seizures were similar in Ha- and HI-treated animals at the beginning of the hypoxic insult, Ha caused a more severe electrographic seizure profile than HI near the end. Analyses of power spectral density and seizure frequency profiles indicated that the electrographic seizures progressively increased during the 2-h Ha treatment, while HI led to a progressive decrease in the seizures with significant suppression of the EEG background. These data show that 1) the hypoxia component of these two models drives the seizures; 2) the seizures during Ha are substantially more robust than those during HI, possibly because ongoing neuronal damage blunts the electrographic activity; and 3) a progressive decrease in background EEG, rather than the presence of electrographic seizures, indicates neuronal degeneration during perinatal HI.
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Affiliation(s)
- A Zayachkivsky
- Department of Neurosurgery, University of Utah School of Medicine, Salt Lake City, Utah; and
| | - M J Lehmkuhle
- Department of Neurosurgery, University of Utah School of Medicine, Salt Lake City, Utah; and
| | - J J Ekstrand
- Department of Pediatrics, University of Utah School of Medicine, Salt Lake City, Utah
| | - F E Dudek
- Department of Neurosurgery, University of Utah School of Medicine, Salt Lake City, Utah; and
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Rodriguez-Alvarez N, Jimenez-Mateos EM, Dunleavy M, Waddington JL, Boylan GB, Henshall DC. Effects of hypoxia-induced neonatal seizures on acute hippocampal injury and later-life seizure susceptibility and anxiety-related behavior in mice. Neurobiol Dis 2015; 83:100-14. [PMID: 26341542 DOI: 10.1016/j.nbd.2015.08.023] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2015] [Revised: 08/06/2015] [Accepted: 08/21/2015] [Indexed: 12/30/2022] Open
Abstract
Seizures are common during the neonatal period, often due to hypoxic-ischemic encephalopathy and may contribute to acute brain injury and the subsequent development of cognitive deficits and childhood epilepsy. Here we explored short- and long-term consequences of neonatal hypoxia-induced seizures in 7 day old C57BL/6J mice. Seizure activity, molecular markers of hypoxia and histological injury were investigated acutely after hypoxia and response to chemoconvulsants and animal behaviour was explored at adulthood. Hypoxia was induced by exposing pups to 5% oxygen for 15 min (global hypoxia). Electrographically defined seizures with behavioral correlates occurred in 95% of these animals and seizures persisted for many minutes after restitution of normoxia. There was minimal morbidity or mortality. Pre- or post-hypoxia injection of phenobarbital (50mg/kg) had limited efficacy at suppressing seizures. The hippocampus from neonatal hypoxia-seizure mice displayed increased expression of vascular endothelial growth factor and the immediate early gene c-fos, minimal histological evidence of cell injury and activation of caspase-3 in scattered neurons. Behavioral analysis of mice five weeks after hypoxia-induced seizures detected novel anxiety-related and other behaviors, while performance in a spatial memory test was similar to controls. Seizure threshold tests with kainic acid at six weeks revealed that mice previously subject to neonatal hypoxia-induced seizures developed earlier, more frequent and longer-duration seizures. This study defines a set of electro-clinical, molecular, pharmacological and behavioral consequences of hypoxia-induced seizures that indicate short- and long-term deleterious outcomes and may be a useful model to investigate the pathophysiology and treatment of neonatal seizures in humans.
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Affiliation(s)
| | - Eva M Jimenez-Mateos
- Department of Physiology & Medical Physics, Royal College of Surgeons in Ireland, Dublin, Ireland
| | - Mark Dunleavy
- Department of Physiology & Medical Physics, Royal College of Surgeons in Ireland, Dublin, Ireland
| | - John L Waddington
- Department of Molecular and Cellular Therapeutics, Royal College of Surgeons in Ireland, Dublin, Ireland
| | - Geraldine B Boylan
- Irish Centre for Fetal and Neonatal Translational Research (INFANT), Cork, Ireland
| | - David C Henshall
- Department of Physiology & Medical Physics, Royal College of Surgeons in Ireland, Dublin, Ireland; Irish Centre for Fetal and Neonatal Translational Research (INFANT), Cork, Ireland.
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