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Yonan JM, Chen KD, Baram TZ, Steward O. PTEN DELETION IN THE ADULT DENTATE GYRUS INDUCES EPILEPSY. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.08.07.606938. [PMID: 39149280 PMCID: PMC11326251 DOI: 10.1101/2024.08.07.606938] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 08/17/2024]
Abstract
Embryonic and early postnatal promotor-driven deletion of the phosphatase and tensin homolog (PTEN) gene results in neuronal hypertrophy, hyperexcitable circuitry and development of spontaneous seizures in adulthood. We previously documented that focal, vector-mediated PTEN deletion in mature granule cells of adult dentate gyrus triggers dramatic growth of cell bodies, dendrites, and axons, similar to that seen with early postnatal PTEN deletion. Here, we assess the functional consequences of focal, adult PTEN deletion, focusing on its pro-epileptogenic potential. PTEN deletion was accomplished by injecting AAV-Cre either bilaterally or unilaterally into the dentate gyrus of double transgenic PTEN-floxed, ROSA-reporter mice. Hippocampal recording electrodes were implanted for continuous digital EEG with concurrent video recordings in the home cage. Electrographic seizures and epileptiform spikes were assessed manually by two investigators, and corelated with concurrent videos. Spontaneous electrographic and behavioral seizures appeared after focal PTEN deletion in adult dentate granule cells, commencing around 2 months post-AAV-Cre injection. Seizures occurred in the majority of mice with unilateral or bilateral PTEN deletion and led to death in several cases. PTEN-deletion provoked epilepsy was not associated with apparent hippocampal neuron death; supra-granular mossy fiber sprouting was observed in a few mice. In summary, focal, unilateral deletion of PTEN in the adult dentate gyrus suffices to provoke time-dependent emergence of a hyperexcitable circuit generating hippocampus-origin, generalizing spontaneous seizures, providing a novel model for studies of adult-onset epileptogenesis.
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Affiliation(s)
- Jennifer M Yonan
- Reeve-Irvine Research Center, Departments of Anatomy & Neurobiology, Neurobiology & Behavior, Neurosurgery, Pediatrics and Neurology, Center for the Neurobiology of Learning and Memory, University of California at Irvine, Irvine, CA 92697
| | - Kevin D Chen
- Reeve-Irvine Research Center, Departments of Anatomy & Neurobiology, Neurobiology & Behavior, Neurosurgery, Pediatrics and Neurology, Center for the Neurobiology of Learning and Memory, University of California at Irvine, Irvine, CA 92697
| | - Tallie Z Baram
- Reeve-Irvine Research Center, Departments of Anatomy & Neurobiology, Neurobiology & Behavior, Neurosurgery, Pediatrics and Neurology, Center for the Neurobiology of Learning and Memory, University of California at Irvine, Irvine, CA 92697
| | - Oswald Steward
- Reeve-Irvine Research Center, Departments of Anatomy & Neurobiology, Neurobiology & Behavior, Neurosurgery, Pediatrics and Neurology, Center for the Neurobiology of Learning and Memory, University of California at Irvine, Irvine, CA 92697
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2
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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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Fábera P, Uttl L, Kubová H, Tsenov G, Mareš P. Adenosine Kinase Isoforms in the Developing Rat Hippocampus after LiCl/Pilocarpine Status Epilepticus. Int J Mol Sci 2022; 23:ijms23052510. [PMID: 35269653 PMCID: PMC8910300 DOI: 10.3390/ijms23052510] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2022] [Revised: 02/21/2022] [Accepted: 02/22/2022] [Indexed: 01/27/2023] Open
Abstract
LiCl/pilocarpine status epilepticus (SE) induced in immature rats leads, after a latent period, to hippocampal hyperexcitability. The excitability may be influenced by adenosine, which exhibits anticonvulsant activity. The concentration of adenosine is regulated by adenosine kinase (ADK) present in two isoforms—ADK-L and ADK-S. The main goal of the study is to elucidate the changes in ADK isoform expression after LiCl/pilocarpine SE and whether potential changes, as well as inhibition of ADK by 5-iodotubercidin (5-ITU), may contribute to changes in hippocampal excitability during brain development. LiCl/pilocarpine SE was elicited in 12-day-old rats. Hippocampal excitability in immature rats was studied by the model of hippocampal afterdischarges (ADs), in which we demonstrated the potential inhibitory effect of 5-ITU. ADs demonstrated significantly decreased hippocampal excitability 3 days after SE induction, whereas significant hyperexcitability after 20 days compared to controls was shown. 5-ITU administration showed its inhibitory effect on the ADs in 32-day-old SE rats compared to SE rats without 5-ITU. Moreover, both ADK isoforms were examined in the immature rat hippocampus. The ADK-L isoform demonstrated significantly decreased expression in 12-day-old SE rats compared to the appropriate naïve rats, whereas increased ADK-S isoform expression was revealed. A decreasing ADK-L/-S ratio showed the declining dominance of ADK-L isoform during early brain development. LiCl/pilocarpine SE increased the excitability of the hippocampus 20 days after SE induction. The ADK inhibitor 5-ITU exhibited anticonvulsant activity at the same age. Age-related differences in hippocampal excitability after SE might correspond to the development of ADK isoform levels in the hippocampus.
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Affiliation(s)
- Petr Fábera
- Department of Developmental Epileptology, Institute of Physiology, Czech Academy of Sciences, 14200 Prague, Czech Republic; (L.U.); (H.K.); (G.T.); (P.M.)
- Department of Neurology, Second Faculty of Medicine, Motol University Hospital, Charles University, 15006 Prague, Czech Republic
- Correspondence: ; Tel.: +42-073-272-8308; Fax: +42-022-443-6875
| | - Libor Uttl
- Department of Developmental Epileptology, Institute of Physiology, Czech Academy of Sciences, 14200 Prague, Czech Republic; (L.U.); (H.K.); (G.T.); (P.M.)
- National Institute of Mental Health, 25067 Klecany, Czech Republic
| | - Hana Kubová
- Department of Developmental Epileptology, Institute of Physiology, Czech Academy of Sciences, 14200 Prague, Czech Republic; (L.U.); (H.K.); (G.T.); (P.M.)
| | - Grygoriy Tsenov
- Department of Developmental Epileptology, Institute of Physiology, Czech Academy of Sciences, 14200 Prague, Czech Republic; (L.U.); (H.K.); (G.T.); (P.M.)
- National Institute of Mental Health, 25067 Klecany, Czech Republic
| | - Pavel Mareš
- Department of Developmental Epileptology, Institute of Physiology, Czech Academy of Sciences, 14200 Prague, Czech Republic; (L.U.); (H.K.); (G.T.); (P.M.)
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The Protective Role of E-64d in Hippocampal Excitotoxic Neuronal Injury Induced by Glutamate in HT22 Hippocampal Neuronal Cells. Neural Plast 2021; 2021:7174287. [PMID: 34721570 PMCID: PMC8550833 DOI: 10.1155/2021/7174287] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2021] [Revised: 09/14/2021] [Accepted: 10/01/2021] [Indexed: 12/25/2022] Open
Abstract
Epilepsy is the most common childhood neurologic disorder. Status epilepticus (SE), which refers to continuous epileptic seizures, occurs more frequently in children than in adults, and approximately 40–50% of all cases occur in children under 2 years of age. Conventional antiepileptic drugs currently used in clinical practice have a number of adverse side effects. Drug-resistant epilepsy (DRE) can progressively develop in children with persistent SE, necessitating the development of novel therapeutic drugs. During SE, the persistent activation of neurons leads to decreased glutamate clearance with corresponding glutamate accumulation in the synaptic extracellular space, increasing the chance of neuronal excitotoxicity. Our previous study demonstrated that after developmental seizures in rats, E-64d exerts a neuroprotective effect on the seizure-induced brain damage by modulating lipid metabolism enzymes, especially ApoE and ApoJ/clusterin. In this study, we investigated the impact and mechanisms of E-64d administration on neuronal excitotoxicity. To test our hypothesis that E-64d confers neuroprotective effects by regulating autophagy and mitochondrial pathway activity, we simulated neuronal excitotoxicity in vitro using an immortalized hippocampal neuron cell line (HT22). We found that E-64d improved cell viability while reducing oxidative stress and neuronal apoptosis. In addition, E-64d treatment regulated mitochondrial pathway activity and inhibited chaperone-mediated autophagy in HT22 cells. Our findings indicate that E-64d may alleviate glutamate-induced damage via regulation of mitochondrial fission and apoptosis, as well as inhibition of chaperone-mediated autophagy. Thus, E-64d may be a promising therapeutic treatment for hippocampal injury associated with SE.
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Larson EA, Accardi MV, Zhong Y, Paquette D, Authier S. Drug-Induced Seizures: Considerations for Underlying Molecular Mechanisms. Int J Toxicol 2021; 40:403-412. [PMID: 34514888 DOI: 10.1177/10915818211040483] [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: 11/15/2022]
Abstract
A broad spectrum of chemical entities have been associated with drug-induced seizure (DIS), emphasizing the importance of this potential liability across various drug classes (e.g., antidepressants, antipsychotics, antibiotics, and analgesics among others). Despite its importance within drug safety testing, an understanding of the molecular mechanisms associated with DIS is often lacking. The etiology of DIS is understood to be a result of either a deficit in inhibitory (e.g., gamma aminobutyric acid) or an elevated excitatory (e.g., glutamate) signaling, leading to synchronous neuronal depolarization affecting various brain regions and impairing normal neurological functions. How this altered neuronal signaling occurs and how these changes interact with other non-brain receptor driven DIS-associated changes such as metabolic disturbances, electrolyte imbalances, altered drug metabolism, and withdrawal effects are poorly understood. Herein, we discuss important molecular mechanisms identified in DIS for several drugs and/or drug classes. With a better understanding of the molecular mechanisms associated with DIS, in vivo or in vitro models may be applied to characterize and mitigate DIS risk during drug development. Susceptibility stratification for DIS presents species differences in the following order beagle dogs > rodents and cynomolgus monkeys > Göttingen minipigs with a more than 2-fold difference between canines and minipigs, which is important to consider during non-clinical species selection. While clinical signs such as myoclonus, severe muscle jerks, or convulsions are often associated with abnormal epileptiform EEG activity, tremors are most of the time physiological and rarely observed with concurrent epileptiform EEG activity which need to be considered during DIS risk evaluation.
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Affiliation(s)
| | | | - Yifei Zhong
- Charles River Laboratories, Laval, Quebec, Canada
| | | | - Simon Authier
- Charles River Laboratories, Laval, Quebec, Canada.,Faculté de Médecine Vétérinaire, Université de Montréal, St-Hyacinthe, Quebec, Canada
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6
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Wu Q, Zhang M, Liu X, Zhang J, Wang H. CB2R orchestrates neuronal autophagy through regulation of the mTOR signaling pathway in the hippocampus of developing rats with status epilepticus. Int J Mol Med 2019; 45:475-484. [PMID: 31894322 PMCID: PMC6984801 DOI: 10.3892/ijmm.2019.4439] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2019] [Accepted: 11/29/2019] [Indexed: 12/11/2022] Open
Abstract
Neuronal loss and gliosis are the major pathological changes after status epilepticus (SE). The authors' previous study revealed the time-dependent changes of cannabinoid receptor type 2 (CB2R) in hippocampal neurons of developing rats after SE, which were accompanied by a decrease in the number of neurons. Meanwhile, growing evidence indicates that CB2R stimulation exerts anti-convulsant properties in seizure models. However, the activation of CB2R in neuronal repair in response to the damage after SE is still unclear. In this experiment, a highly-selective CB2R agonist JWH133 and antagonist AM630 were administered to determine the activity of CB2R in neuronal autophagy and apoptosis of the post-SE repair in developing rats. The present results revealed that activation of CB2R by JWH133, not only obviously lowered the success rate, 24-h death rate and the Racine stage in the model, but also extended the latency period to SE. In addition, compared with the vehicle control group, CB2R activation increased neuronal autophagy and the expression of phosphorylated-mammalian target of rapamycin (p-mTOR)/mTOR, Beclin-1, and LC3II/LC3I while decreasing the expression of p-Unc-51-like autophagy-activating kinase 1 (ULK-1)/ULK1, p62, and cleaved caspase-3. These results were dose-dependent and were especially evident in the high-dose group, and interestingly the opposite results were obtained in the AM630 group. Thus, CB2R orchestrates neuronal autophagy through regulation of the mTOR signaling pathway in the hippocampus of developing rats with SE. These findings might provide an important basis for further investigation of the therapeutic role of CB2R in ameliorating epilepsy-related neuronal damage.
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Affiliation(s)
- Qiong Wu
- Department of Pediatric Neurology, Shengjing Hospital of China Medical University, Shenyang, Liaoning 110004, P.R. China
| | - Miao Zhang
- Department of Forensic Pathology, China Medical University School of Forensic Medicine, Shenyang, Liaoning 110122, P.R. China
| | - Xueyan Liu
- Department of Pediatric Neurology, Shengjing Hospital of China Medical University, Shenyang, Liaoning 110004, P.R. China
| | - Junmei Zhang
- Department of Pediatric Neurology, Shengjing Hospital of China Medical University, Shenyang, Liaoning 110004, P.R. China
| | - Hua Wang
- Department of Pediatric Neurology, Shengjing Hospital of China Medical University, Shenyang, Liaoning 110004, P.R. China
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7
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Rigas P, Sigalas C, Nikita M, Kaplanian A, Armaos K, Leontiadis LJ, Zlatanos C, Kapogiannatou A, Peta C, Katri A, Skaliora I. Long-Term Effects of Early Life Seizures on Endogenous Local Network Activity of the Mouse Neocortex. Front Synaptic Neurosci 2018; 10:43. [PMID: 30538627 PMCID: PMC6277496 DOI: 10.3389/fnsyn.2018.00043] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2018] [Accepted: 11/06/2018] [Indexed: 12/17/2022] Open
Abstract
Understanding the long term impact of early life seizures (ELS) is of vital importance both for researchers and clinicians. Most experimental studies of how seizures affect the developing brain have drawn their conclusions based on changes detected at the cellular or behavioral level, rather than on intermediate levels of analysis, such as the physiology of neuronal networks. Neurons work as part of networks and network dynamics integrate the function of molecules, cells and synapses in the emergent properties of brain circuits that reflect the balance of excitation and inhibition in the brain. Therefore, studying network dynamics could help bridge the cell-to-behavior gap in our understanding of the neurobiological effects of seizures. To this end we investigated the long-term effects of ELS on local network dynamics in mouse neocortex. By using the pentylenetetrazole (PTZ)-induced animal model of generalized seizures, single or multiple seizures were induced at two different developmental stages (P9-15 or P19-23) in order to examine how seizure severity and brain maturational status interact to affect the brain's vulnerability to ELS. Cortical physiology was assessed by comparing spontaneous network activity (in the form of recurring Up states) in brain slices of adult (>5 mo) mice. In these experiments we examined two distinct cortical regions, the primary motor (M1) and somatosensory (S1) cortex in order to investigate regional differences in vulnerability to ELS. We find that the effects of ELSs vary depending on (i) the severity of the seizures (e.g., single intermittent ELS at P19-23 had no effect on Up state activity, but multiple seizures induced during the same period caused a significant change in the spectral content of spontaneous Up states), (ii) the cortical area examined, and (iii) the developmental stage at which the seizures are administered. These results reveal that even moderate experiences of ELS can have long lasting age- and region-specific effects in local cortical network dynamics.
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Affiliation(s)
- Pavlos Rigas
- Biomedical Research Foundation of the Academy of Athens, Athens, Greece
| | | | - Maria Nikita
- Biomedical Research Foundation of the Academy of Athens, Athens, Greece
| | - Ani Kaplanian
- Biomedical Research Foundation of the Academy of Athens, Athens, Greece
| | | | | | - Christos Zlatanos
- Biomedical Research Foundation of the Academy of Athens, Athens, Greece
| | | | - Charoula Peta
- Biomedical Research Foundation of the Academy of Athens, Athens, Greece
| | - Anna Katri
- Biomedical Research Foundation of the Academy of Athens, Athens, Greece
| | - Irini Skaliora
- Biomedical Research Foundation of the Academy of Athens, Athens, Greece
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Abstract
Epilepsy is a chronic neurological disorder affecting 65 million people worldwide. The etiologies of seizures can often be identified as genetic, metabolic, structural, immunologic or infectious, but in many cases the cause is unknown with the current diagnostic tools. Epileptogenesis is a process during which genetic or other acquired etiologies/insults lead to functional, structural, or network reorganization changes in the brain that may lead to the development of, or progression of, spontaneous seizures. During development, there are continuous changes in the structure, function, and network operation that also show sex specificity, which may alter the mechanisms underlying the generation of seizures (ictogenesis) and epileptogenesis. Understanding the mechanisms of early life epileptogenesis will enable the development of rationally designed age- and sex-appropriate therapies that would improve the overall quality of patients' lives. Here, we discuss some of these processes that may affect seizure generation and epileptogenesis in the neonatal brain.
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Affiliation(s)
- Anna-Maria Katsarou
- Saul R. Korey Department of Neurology, Albert Einstein College of Medicine, Bronx, New York, USA,Laboratory of Developmental Epilepsy, Albert Einstein College of Medicine, Bronx, New York, USA
| | - Aristea S. Galanopoulou
- Saul R. Korey Department of Neurology, Albert Einstein College of Medicine, Bronx, New York, USA,Laboratory of Developmental Epilepsy, Albert Einstein College of Medicine, Bronx, New York, USA,Montefiore/Einstein Epilepsy Center, Albert Einstein College of Medicine, Bronx, New York, USA,Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, New York, USA
| | - Solomon L. Moshé
- Saul R. Korey Department of Neurology, Albert Einstein College of Medicine, Bronx, New York, USA,Laboratory of Developmental Epilepsy, Albert Einstein College of Medicine, Bronx, New York, USA,Montefiore/Einstein Epilepsy Center, Albert Einstein College of Medicine, Bronx, New York, USA,Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, New York, USA,Department of Pediatrics, Albert Einstein College of Medicine, Bronx, New York, USA,Corresponding author. Address: Department of Neurology, Albert Einstein College of Medicine, 1410 Pelham Parkway South, Rose F. Kennedy Center, Rm 316, Bronx, NY 10461, USA. Tel.: +1 718-430-2447; fax: +1 718-430-8899. (S.L. Moshé)
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9
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Wang J, Li Y, Huang WH, Zeng XC, Li XH, Li J, Zhou J, Xiao J, Xiao B, Ouyang DS, Hu K. The Protective Effect of Aucubin from Eucommia ulmoides Against Status Epilepticus by Inducing Autophagy and Inhibiting Necroptosis. THE AMERICAN JOURNAL OF CHINESE MEDICINE 2017; 45:557-573. [PMID: 28387136 DOI: 10.1142/s0192415x17500331] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Eucommia ulmoides Oliv. is a famous traditional Chinese medicine which exhibits anti-oxidative stress ability and neuro-protective effects. Aucubin is the predominant component of Eucommia ulmoides Oliv. Our present study is intended to investigate aucubin's potential protective effects on neurons against epilepsy in the hippocampus by establishing the lithium-pilocarpine induced status epilepticus (SE) rat model in vivo. Aucubin (at a low dose and a high dose of 5[Formula: see text]mg/kg and 10[Formula: see text]mg/kg, respectively) was administered through gavage for two weeks before lithium-pilocarpine injection. Rats were sacrificed at 4, 24 and 72[Formula: see text]h after SE induction. Pretreatment with both low-dose and high-dose aucubin significantly reduced the number of death neurons ([Formula: see text]) and increased the number of surviving neurons ([Formula: see text]) in DG, Hilus, CA1 and CA3 hippocampal regions post SE. Meanwhile, it significantly inhibited necroptosis proteins (MLKL and RIP-1) ([Formula: see text] or [Formula: see text]) and enhanced autophagy protein (Beclin-1 and LC3BII/LC3BI) prevalence in the hippocampus ([Formula: see text] or [Formula: see text]). In conclusion, aucubin appeared to ameliorate damages in lithium-pilocarpine induced SE in hippocampus, reduce the number of apoptotic neurons, and increased the number of survival neurons by inducing autophagy and inhibiting necroptosis. These original findings might provide an important basis for the further investigation of the therapeutic role of aucubin in treatment or prevention of epilepsy-related neuronal damages.
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Affiliation(s)
- Jin Wang
- ** Department of Pharmacology, School of Pharmaceutical Science, Central South University, Changsha 410000, P.R. China
| | - Ying Li
- †† Department of Healthy Management Center, The Third Xiangya Hospital, Central South University, Changsha 410013, P.R. China
| | - Wei-Hua Huang
- † Department of Clinical Pharmacology, Xiangya Hospital, Central South University, Changsha 410008, P.R. China.,∥ Institute of Clinical Pharmacology, Hunan Key Laboratory of Pharmacogenetics, Central South University, Changsha 410078, P.R. China
| | - Xiang-Chang Zeng
- † Department of Clinical Pharmacology, Xiangya Hospital, Central South University, Changsha 410008, P.R. China.,∥ Institute of Clinical Pharmacology, Hunan Key Laboratory of Pharmacogenetics, Central South University, Changsha 410078, P.R. China
| | - Xiao-Hui Li
- ** Department of Pharmacology, School of Pharmaceutical Science, Central South University, Changsha 410000, P.R. China
| | - Jian Li
- ‡ Department of Laboratory Medicine, Xiangya School of Medicine, Central South University, Changsha 410008, P.R. China
| | - Jun Zhou
- § Medical Science Research Center, Xiangya Hospital, Central South University, Changsha 410008, P.R. China
| | - Jian Xiao
- ¶ Department of Pharmacy, Xiangya Hospital, Central South University, Changsha 410008, P.R. China
| | - Bo Xiao
- * Department of Neurology, Xiangya Hospital, Central South University, Changsha 410008, P.R. China
| | - Dong-Sheng Ouyang
- † Department of Clinical Pharmacology, Xiangya Hospital, Central South University, Changsha 410008, P.R. China.,∥ Institute of Clinical Pharmacology, Hunan Key Laboratory of Pharmacogenetics, Central South University, Changsha 410078, P.R. China
| | - Kai Hu
- * Department of Neurology, Xiangya Hospital, Central South University, Changsha 410008, P.R. China
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10
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Patterson KP, Barry JM, Curran MM, Singh-Taylor A, Brennan G, Rismanchi N, Page M, Noam Y, Holmes GL, Baram TZ. Enduring Memory Impairments Provoked by Developmental Febrile Seizures Are Mediated by Functional and Structural Effects of Neuronal Restrictive Silencing Factor. J Neurosci 2017; 37:3799-3812. [PMID: 28275159 PMCID: PMC5394897 DOI: 10.1523/jneurosci.3748-16.2017] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2016] [Revised: 02/25/2017] [Accepted: 02/28/2017] [Indexed: 12/22/2022] Open
Abstract
In a subset of children experiencing prolonged febrile seizures (FSs), the most common type of childhood seizures, cognitive outcomes are compromised. However, the underlying mechanisms are unknown. Here we identified significant, enduring spatial memory problems in male rats following experimental prolonged FS (febrile status epilepticus; eFSE). Remarkably, these deficits were abolished by transient, post hoc interference with the chromatin binding of the transcriptional repressor neuron restrictive silencing factor (NRSF or REST). This transcriptional regulator is known to contribute to neuronal differentiation during development and to programmed gene expression in mature neurons. The mechanisms of the eFSE-provoked memory problems involved complex disruption of memory-related hippocampal oscillations recorded from CA1, likely resulting in part from impairments of dendritic filtering of cortical inputs as well as abnormal synaptic function. Accordingly, eFSE provoked region-specific dendritic loss in the hippocampus, and aberrant generation of excitatory synapses in dentate gyrus granule cells. Blocking NRSF transiently after eFSE prevented granule cell dysmaturation, restored a functional balance of γ-band network oscillations, and allowed treated eFSE rats to encode and retrieve spatial memories. Together, these studies provide novel insights into developing networks that underlie memory, the mechanisms by which early-life seizures influence them, and the means to abrogate the ensuing cognitive problems.SIGNIFICANCE STATEMENT Whereas seizures have been the central focus of epilepsy research, they are commonly accompanied by cognitive problems, including memory impairments that contribute to poor quality of life. These deficits often arise before the onset of spontaneous seizures, or independent from them, yet the mechanisms involved are unclear. Here, using a rodent model of common developmental seizures that provoke epilepsy in a subset of individuals, we identify serious consequent memory problems. We uncover molecular, cellular, and circuit-level mechanisms that underlie these deficits and successfully abolish them by targeted therapeutic interventions. These findings may be important for understanding and preventing cognitive problems in individuals suffering long febrile seizures.
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Affiliation(s)
| | - Jeremy M Barry
- Department of Neurological Sciences, University of Vermont College of Medicine, Burlington, Vermont 05405
| | | | | | - Gary Brennan
- Departments of Anatomy/Neurobiology
- Pediatrics, and
| | | | - Matias Page
- Department of Neurological Sciences, University of Vermont College of Medicine, Burlington, Vermont 05405
| | | | - Gregory L Holmes
- Department of Neurological Sciences, University of Vermont College of Medicine, Burlington, Vermont 05405
| | - Tallie Z Baram
- Departments of Anatomy/Neurobiology,
- Pediatrics, and
- Neurology, University of California-Irvine, Irvine, California 92697-4475, and
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11
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A Time and Place for Everything: Early-Life Seizures at Different Developmental Epochs Have Distinct Effects on Adult Hippocampal Structure and Function. Epilepsy Curr 2016; 16:106-7. [DOI: 10.5698/1535-7511-16.2.106] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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12
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Rapid, Coordinate Inflammatory Responses after Experimental Febrile Status Epilepticus: Implications for Epileptogenesis. eNeuro 2015; 2:eN-NWR-0034-15. [PMID: 26730400 PMCID: PMC4699830 DOI: 10.1523/eneuro.0034-15.2015] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2015] [Revised: 09/25/2015] [Accepted: 09/28/2015] [Indexed: 11/29/2022] Open
Abstract
Epilepsy is a common neurological disorder with many causes. For temporal lobe epilepsy, antecedent insults are typically found. These risk factors include trauma or history of long fever-associated seizures (febrile status epilepticus) in childhood. Whereas the mechanisms by which such insults promote temporal lobe epilepsy are unknown, an extensive body of work has implicated inflammation and inflammatory mediators in both human and animal models of the disorder. However, direct evidence for an epileptogenic role for inflammation is lacking. Here we capitalized on a model where only a subgroup of insult-experiencing rodents develops epilepsy. We reasoned that if inflammation was important for generating epilepsy, then early inflammation should be more prominent in individuals destined to become epileptic compared with those that will not become epileptic. In addition, the molecular and temporal profile of inflammatory mediators would provide insights into which inflammatory pathways might be involved in the disease process. We examined inflammatory profiles in hippocampus and amygdala of individual rats and correlated them with a concurrent noninvasive, amygdalar magnetic resonance imaging epilepsy-predictive marker. We found significant individual variability in the expression of several important inflammatory mediators, but not in others. Of interest, a higher expression of a subset of hippocampal and amygdalar inflammatory markers within the first few hours following an insult correlated with the epilepsy-predictive signal. These findings suggest that some components of the inflammatory gene network might contribute to the process by which insults promote the development of temporal lobe epilepsy.
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In vivo effects of bumetanide at brain concentrations incompatible with NKCC1 inhibition on newborn DGC structure and spontaneous EEG seizures following hypoxia-induced neonatal seizures. Neuroscience 2014; 286:203-15. [PMID: 25463517 DOI: 10.1016/j.neuroscience.2014.11.031] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2014] [Revised: 11/17/2014] [Accepted: 11/18/2014] [Indexed: 12/21/2022]
Abstract
Neonatal seizures caused by perinatal asphyxia and hypoxic-ischemic encephalopathy can be refractory to conventional anticonvulsants. This may be due to the depolarizing effects of gamma-aminobutyric acid (GABA) achieved by the activity of the Na(+)-K(+)-2Cl(-) cotransporter (NKCC1). The aim of this study is to evaluate the long-term effects of bumetanide, a NKCC1 inhibitor, on hippocampal neurogenesis and seizure susceptibility in hypoxia-induced neonatal seizure model. Wistar rats were subjected to hypoxia-induced neonatal seizures at postnatal day 10 (P10). Following acute seizures, the rats were treated with intraperitoneal injection (i.p.) of bumetanide at a dose of 0.5mg/kg for 3 weeks. In later adulthood, hypoxia-induced seizures increased the number of newborn dentate gyrus cells (DGCs), promoted mossy fiber sprouting (MFS) and reduced the apical dendritic complexity of newborn DGCs 1 month after the insults. In addition, these seizures resulted in long-lasting consequences, such as spontaneous electroencephalography (EEG) seizures, though spatial learning impairments were not seen. Bumetanide treatments significantly enhanced cell proliferation and dendritic development of newborn DGCs after neonatal seizures, accompanied by the decreased seizure activity. However, systemic administration of bumetanide resulted in much lower brain concentrations, and was incompatible with NKCC1 inhibition in blood-brain barrier (BBB)-protected brain tissue. Our results suggested that bumetanide might have long-term effects in suppressing seizure activity, and altering the neurogenesis after neonatal seizures. These effects of bumetanide may be mediated by the targets outside the BBB-protected central nerve system (CNS) or CNS-located target(s) other than NKCC1.
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van der Hel WS, Hessel EVS, Bos IWM, Mulder SD, Verlinde SAMW, van Eijsden P, de Graan PNE. Persistent reduction of hippocampal glutamine synthetase expression after status epilepticus in immature rats. Eur J Neurosci 2014; 40:3711-9. [PMID: 25350774 DOI: 10.1111/ejn.12756] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2013] [Revised: 09/13/2014] [Accepted: 09/22/2014] [Indexed: 01/16/2023]
Abstract
Mesiotemporal sclerosis (MTS), the most frequent form of drug-resistant temporal lobe epilepsy, often develops after an initial precipitating injury affecting the immature brain. To analyse early processes in epileptogenesis we used the juvenile pilocarpine model to study status epilepticus (SE)-induced changes in expression of key components in the glutamate-glutamine cycle, known to be affected in MTS patients. SE was induced by Li(+) /pilocarpine injection in 21-day-old rats. At 2-19 weeks after SE hippocampal protein expression was analysed by immunohistochemistry and neuron damage by FluoroJade staining. Spontaneous seizures occurred in at least 44% of animals 15-18 weeks after SE. As expected in this model, we did not observe loss of principal hippocampal neurons. Neuron damage was most pronounced in the hilus, where we also detected progressive loss of parvalbumin-positive GABAergic interneurons. Hilar neuron loss (or end-folium sclerosis), a common feature in patients with MTS, was accompanied by a progressively decreased glutamine synthetase (GS)-immunoreactivity from 2 (-15%) to 19 weeks (-33.5%) after SE. Immunoreactivity for excitatory amino-acid transporters, vesicular glutamate transporter 1 and glial fibrillary acidic protein was unaffected. Our data show that SE elicited in 21-day-old rats induces a progressive reduction in hilar GS expression without affecting other key components of the glutamate-glutamine cycle. Reduced expression of glial enzyme GS was first detected 2 weeks after SE, and thus clearly before spontaneous recurrent seizures occurred. These results support the hypothesis that reduced GS expression is an early event in the development of hippocampal sclerosis in MTS patients and emphasize the importance of astrocytes in early epileptogenesis.
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Affiliation(s)
- W Saskia van der Hel
- Department of Translational Neuroscience, Brain Center Rudolf Magnus, University Medical Center Utrecht, Universiteitsweg 100, 3584CG, Utrecht, The Netherlands; Division of Surgical Specialties, Department of Anatomy, University Medical Center Utrecht, Utrecht, The Netherlands
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Abstract
A significant proportion of temporal lobe epilepsy (TLE), a common, intractable brain disorder, arises in children with febrile status epilepticus (FSE). Preventative therapy development is hampered by our inability to identify early the FSE individuals who will develop TLE. In a naturalistic rat model of FSE, we used high-magnetic-field MRI and long-term video EEG to seek clinically relevant noninvasive markers of epileptogenesis and found that reduced amygdala T2 relaxation times in high-magnetic-field MRI hours after FSE predicted experimental TLE. Reduced T2 values likely represented paramagnetic susceptibility effects derived from increased unsaturated venous hemoglobin, suggesting augmented oxygen utilization after FSE termination. Indeed, T2 correlated with energy-demanding intracellular translocation of the injury-sensor high-mobility group box 1 (HMGB1), a trigger of inflammatory cascades implicated in epileptogenesis. Use of deoxyhemoglobin-sensitive MRI sequences enabled visualization of the predictive changes on lower-field, clinically relevant scanners. This novel MRI signature delineates the onset and suggests mechanisms of epileptogenesis that follow experimental FSE.
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Scholl EA, Dudek FE, Ekstrand JJ. Neuronal degeneration is observed in multiple regions outside the hippocampus after lithium pilocarpine-induced status epilepticus in the immature rat. Neuroscience 2013; 252:45-59. [PMID: 23896573 DOI: 10.1016/j.neuroscience.2013.07.045] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2013] [Revised: 07/17/2013] [Accepted: 07/18/2013] [Indexed: 01/25/2023]
Abstract
Although hippocampal sclerosis is frequently identified as a possible epileptic focus in patients with temporal lobe epilepsy, neuronal loss has also been observed in additional structures, including areas outside the temporal lobe. The claim from several researchers using animal models of acquired epilepsy that the immature brain can develop epilepsy without evidence of hippocampal neuronal death raises the possibility that neuronal death in some of these other regions may also be important for epileptogenesis. The present study used the lithium pilocarpine model of acquired epilepsy in immature animals to assess which structures outside the hippocampus are injured acutely after status epilepticus. Sprague-Dawley rat pups were implanted with surface EEG electrodes, and status epilepticus was induced at 20 days of age with lithium pilocarpine. After 72 h, brain tissue from 12 animals was examined with Fluoro-Jade B, a histochemical marker for degenerating neurons. All animals that had confirmed status epilepticus demonstrated Fluoro-Jade B staining in areas outside the hippocampus. The most prominent staining was seen in the thalamus (mediodorsal, paratenial, reuniens, and ventral lateral geniculate nuclei), amygdala (ventral lateral, posteromedial, and basomedial nuclei), ventral premammillary nuclei of hypothalamus, and paralimbic cortices (perirhinal, entorhinal, and piriform) as well as parasubiculum and dorsal endopiriform nuclei. These results demonstrate that lithium pilocarpine-induced status epilepticus in the immature rat brain consistently results in neuronal injury in several distinct areas outside of the hippocampus. Many of these regions are similar to areas damaged in patients with temporal lobe epilepsy, thus suggesting a possible role in epileptogenesis.
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Key Words
- AA
- ACH
- ACo
- AD
- AHC
- AI
- AM
- AO
- APir
- AStr
- AV
- Acb
- AcbSh
- BAOT
- BLA
- BLP
- BLV
- BMA
- BMP
- BSTIA
- BSTM
- CA
- CL
- CM
- CPu
- CeL
- CeM
- Cg1-3
- DEn
- DG
- DI
- DLG
- DP
- EEG
- Ent
- Fluoro-jade B
- Fr1-3
- GABA
- GI
- GP
- HC
- Hil
- I
- IL
- LDDM
- LDVL
- LHb
- LM
- LO
- LOT
- LPLR
- LPMR
- LSD
- LSI
- LSV
- LaD
- LaV
- MD
- MGD
- MGM
- MGP
- MGV
- MHb
- MO
- MS
- MTu
- MeA
- MePD
- MePV
- NAc
- Oc2L
- P
- PC
- PF
- PLCo
- PMCo
- PMD
- PMV
- PRh
- PT
- PVA
- PVP
- PaS
- Par1
- Pir
- Po
- PrS
- RSA
- RSG
- Re
- Rh
- Rt
- S
- SG
- SI
- SNR
- STh
- TLE
- Te1,3
- VL
- VLG
- VLO
- VM
- VP
- VPL
- VPM
- VTR
- ZI
- accumbens
- accumbens shell
- agranular insular cortex
- amygdalopiriform transition area
- amygdalostriatal transition area
- anterior amygdaloid area
- anterior cingulate
- anterior cortical nucleus
- anterior hypothalamic area
- anterior hypothalamic area, central
- anterior olfactory nucleus
- anterodorsal nucleus
- anteromedial
- anteroventral nucleus
- basolateral nucleus, anterior
- basolateral nucleus, posterior
- basolateral nucleus, ventral
- basomedial nucleus, anterior
- basomedial nucleus, posterior
- bed nucleus accessory olfactory tract
- bed nucleus stria terminalis, intraamygdaloid division
- bed stria terminalis nuclei
- caudate putamen
- central nucleus, lateral
- central nucleus, medial
- centrolateral nucleus
- centromedial nucleus
- cornu ammonis
- dentate gyrus
- dorsal endopiriform nucleus
- dorsal peduncular
- dorsolateral geniculate nucleus
- dysgranular insular cortex
- electroencephalogram
- entorhinal cortex
- frontal cortex
- globus pallidus
- granular insular cortex
- hilus
- hippocampus
- immature brain
- infralimbic
- intercalated masses
- lateral habenula
- lateral mammillary
- lateral nucleus, dorsal
- lateral nucleus, ventral
- lateral orbital cortex
- lateral septal, dorsal
- lateral septal, intermediate
- lateral septal, ventral
- laterodorsal nucleus, dorsomedial
- laterodorsal nucleus, ventrolateral
- lateroposterior nucleus, lateral rostral
- lateroposterior nucleus, medial rostral
- lithium pilocarpine
- medial geniculate nucleus, dorsal
- medial geniculate nucleus, medial
- medial geniculate nucleus, ventral
- medial globus pallidus
- medial habenula
- medial nucleus, anterior
- medial nucleus, posterodorsal
- medial nucleus, posteroventral
- medial orbital cortex
- medial septal
- medial tuberal
- mediodorsal nucleus
- nucleus accumbens
- nucleus lateral olfactory tract
- occipital cortex
- paracentral
- parafasicular
- parasubiculum
- paratenial
- paraventricular nucleus, anterior
- paraventricular nucleus, posterior
- parietal cortex
- perirhinal cortex
- piriform cortex
- post-natal day
- posterior nucleus
- posterolateral cortical nucleus
- posteromedial cortical nucleus
- premammillary nucleus, dorsal
- premammillary nucleus, ventral
- presubiculum
- reticular nucleus
- retrosplenial agranular cortex
- retrosplenial granular cortex
- reuniens nucleus
- rhomboid nucleus
- status epilepticus
- subiculum
- substantia innominate
- substantia nigra pars reticulate
- subthalamic nucleus
- suprageniculate nucleus
- temporal cortex
- temporal lobe epilepsy
- vRe
- ventral pallidum
- ventral posterolateral nucleus
- ventral posteromedial nucleus
- ventral reuniens nucleus
- ventral tegmental area
- ventrolateral geniculate nucleus
- ventrolateral nucleus
- ventrolateral orbital cortex
- ventromedial nucleus
- zona incerta
- γ-aminobutyric acid
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Affiliation(s)
- E A Scholl
- Department of Pediatrics, University of Utah School of Medicine, Salt Lake City, Utah, United States
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18
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Abstract
The human brain is a tremendously complex and still enigmatic three-dimensional structure, composed of countless interconnected neurons and glia. The temporal evolution of the brain throughout life provides a fourth dimension, one that influences every element of the brain's function in health and disease. This temporal evolution contributes to the probability of seizure generation and to the type and the nature of these seizures. The age-specific properties of the brain also influence the consequences of seizures on neuronal structure and behavior. These, in turn, govern epileptic activity and cognitive and emotional functions, contributing to the diverse consequences of seizures and epilepsy throughout life.
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Chen LL, Feng HF, Mao XX, Ye Q, Zeng LH. One hour of pilocarpine-induced status epilepticus is sufficient to develop chronic epilepsy in mice, and is associated with mossy fiber sprouting but not neuronal death. Neurosci Bull 2013; 29:295-302. [PMID: 23471864 DOI: 10.1007/s12264-013-1310-6] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2012] [Accepted: 08/20/2012] [Indexed: 11/29/2022] Open
Abstract
Determining the minimal duration of status epilepticus (SE) that leads to the development of subsequent spontaneous seizures (i.e., epilepsy) is important, because it provides a critical time-window for seizure intervention and epilepsy prevention. In the present study, male ICR (Imprinting Control Region) mice were injected with pilocarpine to induce acute seizures. SE was terminated by diazepam at 10 min, 30 min, 1 h, 2 h and 4 h after seizure onset. Spontaneous seizures occurred in the 1, 2 and 4 h SE groups, and the seizure frequency increased with the prolongation of SE. Similarly, the Morris water maze revealed that the escape latency was significantly increased and the number of target quadrant crossings was markedly decreased in the 1, 2 and 4 h SE groups. Robust mossy fiber sprouting was observed in these groups, but not in the 10 or 30 min group. In contrast, Fluoro-Jade B staining revealed significant cell death only in the 4 h SE group. The incidence and frequency of spontaneous seizures were correlated with Timm score (P = 0.004) and escape latency (P = 0.004). These data suggest that SE longer than one hour results in spontaneous motor seizures and memory deficits, and spontaneous seizures are likely associated with robust mossy fiber sprouting but not neuronal death.
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Affiliation(s)
- Ling-Lin Chen
- Department of Pharmacology, College of Medicine, Zhejiang University, Hangzhou, 310058, China
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20
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McKiernan RC, Jimenez-Mateos EM, Bray I, Engel T, Brennan GP, Sano T, Michalak Z, Moran C, Delanty N, Farrell M, O’Brien D, Meller R, Simon RP, Stallings RL, Henshall DC. Reduced mature microRNA levels in association with dicer loss in human temporal lobe epilepsy with hippocampal sclerosis. PLoS One 2012; 7:e35921. [PMID: 22615744 PMCID: PMC3352899 DOI: 10.1371/journal.pone.0035921] [Citation(s) in RCA: 100] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2011] [Accepted: 03/23/2012] [Indexed: 01/22/2023] Open
Abstract
Hippocampal sclerosis (HS) is a common pathological finding in patients with temporal lobe epilepsy (TLE) and is associated with altered expression of genes controlling neuronal excitability, glial function, neuroinflammation and cell death. MicroRNAs (miRNAs), a class of small non-coding RNAs, function as post-transcriptional regulators of gene expression and are critical for normal brain development and function. Production of mature miRNAs requires Dicer, an RNAase III, loss of which has been shown to cause neuronal and glial dysfunction, seizures, and neurodegeneration. Here we investigated miRNA biogenesis in hippocampal and neocortical resection specimens from pharmacoresistant TLE patients and autopsy controls. Western blot analysis revealed protein levels of Dicer were significantly lower in certain TLE patients with HS. Dicer levels were also reduced in the hippocampus of mice subject to experimentally-induced epilepsy. To determine if Dicer loss was associated with altered miRNA processing, we profiled levels of 380 mature miRNAs in control and TLE-HS samples. Expression of nearly 200 miRNAs was detected in control human hippocampus. In TLE-HS samples there was a large-scale reduction of miRNA expression, with 51% expressed at lower levels and a further 24% not detectable. Primary transcript (pri-miRNAs) expression levels for several tested miRNAs were not different between control and TLE-HS samples. These findings suggest loss of Dicer and failure of mature miRNA expression may be a feature of the pathophysiology of HS in patients with TLE.
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Affiliation(s)
- Ross C. McKiernan
- Department of Physiology and Medical Physics, Royal College of Surgeons in Ireland, Dublin, Ireland
| | - Eva M. Jimenez-Mateos
- Department of Physiology and Medical Physics, Royal College of Surgeons in Ireland, Dublin, Ireland
| | - Isabella Bray
- Molecular and Cellular Therapeutics, Royal College of Surgeons in Ireland, Dublin, Ireland
| | - Tobias Engel
- Department of Physiology and Medical Physics, Royal College of Surgeons in Ireland, Dublin, Ireland
| | - Gary P. Brennan
- Department of Physiology and Medical Physics, Royal College of Surgeons in Ireland, Dublin, Ireland
| | - Takanori Sano
- Department of Physiology and Medical Physics, Royal College of Surgeons in Ireland, Dublin, Ireland
| | - Zuzanna Michalak
- Department of Physiology and Medical Physics, Royal College of Surgeons in Ireland, Dublin, Ireland
| | - Catherine Moran
- Department of Physiology and Medical Physics, Royal College of Surgeons in Ireland, Dublin, Ireland
| | - Norman Delanty
- Department of Neurology, Beaumont Hospital, Beaumont, Dublin, Ireland
| | - Michael Farrell
- Department of Pathology, Beaumont Hospital, Beaumont, Dublin, Ireland
| | - Donncha O’Brien
- Department of Neurological Surgery, Beaumont Hospital, Beaumont, Dublin, Ireland
| | - Robert Meller
- Neuroscience Institute, Morehouse School of Medicine, Atlanta, Georgia, United States of America
| | - Roger P. Simon
- Neuroscience Institute, Morehouse School of Medicine, Atlanta, Georgia, United States of America
| | - Raymond L. Stallings
- Molecular and Cellular Therapeutics, Royal College of Surgeons in Ireland, Dublin, Ireland
- National Children’s Research Centre, Our Lady’s Children’s Hospital, Dublin, Ireland
| | - David C. Henshall
- Department of Physiology and Medical Physics, Royal College of Surgeons in Ireland, Dublin, Ireland
- * E-mail:
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21
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Abstract
When mimicking epileptic processes in a laboratory setting, it is important to understand the differences between experimental models of seizures and epilepsy. Because human epilepsy is defined by the appearance of multiple spontaneous recurrent seizures, the induction of a single acute seizure without recurrence does not constitute an adequate epilepsy model. Animal models of epilepsy might be useful for various tasks. They allow for the investigation of pathophysiological mechanisms of the disease, the evaluation, or the development of new antiepileptic treatments, and the study of the consequences of recurrent seizures and neurological and psychiatric comorbidities. Although clinical relevance is always an issue, the development of models of pediatric epilepsies is particularly challenging due to the existence of several key differences in the dynamics of human and rodent brain maturation. Another important consideration in modeling pediatric epilepsy is that "children are not little adults," and therefore a mere application of models of adult epilepsies to the immature specimens is irrelevant. Herein, we review the models of pediatric epilepsy. First, we illustrate the differences between models of pediatric epilepsy and models of the adulthood consequences of a precipitating insult in early life. Next, we focus on new animal models of specific forms of epilepsies that occur in the developing brain. We conclude by emphasizing the deficiencies in the existing animal models and the need for several new models.
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Gomes WA, Shinnar S. Prospects for imaging-related biomarkers of human epileptogenesis: a critical review. Biomark Med 2012; 5:599-606. [PMID: 22003908 DOI: 10.2217/bmm.11.66] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
To facilitate the study of epileptogenesis in humans, noninvasive biomarkers of epileptogenesis are required. No validated biomarker is currently available, but brain imaging techniques provide many attractive candidates. In this article we examine the imaging features of temporal lobe epilepsy, focusing on those that may precede the onset of epilepsy and correlate with epileptogenesis. Hippocampal volumetry and T(2) relaxometry are proposed as candidate biomarkers of epileptogenesis in temporal lobe epilepsy following febrile status epilepticus. Preliminary data suggest that these have promise, and the ongoing Consequences of Prolonged Febrile Seizures in Childhood (FEBSTAT) study will provide more conclusive evidence as to their validity. At this time there are no other clear candidates for imaging-related biomarkers of epileptogenesis in human studies.
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Affiliation(s)
- William A Gomes
- Comprehensive Epilepsy Management Center, Montefiore Medical Center, 111 E. 210th St, Bronx, NY 10467, USA
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23
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O'Dell CM, Das A, Wallace G, Ray SK, Banik NL. Understanding the basic mechanisms underlying seizures in mesial temporal lobe epilepsy and possible therapeutic targets: a review. J Neurosci Res 2012; 90:913-24. [PMID: 22315182 DOI: 10.1002/jnr.22829] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2011] [Revised: 10/05/2011] [Accepted: 10/09/2011] [Indexed: 12/13/2022]
Abstract
Despite years of research, epilepsy remains a poorly understood disorder. In the past several years, work has been conducted on a variety of projects with the goal of better understanding the pathogenesis and progression of mesial temporal lobe epilepsy (MTLE), in particular, and how to exploit those properties to generate innovative therapies for treatment of refractory epilepsies. This review seeks to give an overview of common morphological and biochemical changes associated with epilepsy and proposed treatments to address those changes. Furthering the understanding of ictogenesis and epileptogenesis remains an important goal for scientists seeking to find more effective treatments for MTLE.
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Affiliation(s)
- Casey M O'Dell
- Division of Neurology, Department of Neurosciences, Medical University of South Carolina, Charleston, South Carolina, USA
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Nagarajan L, Ghosh S, Palumbo L, Akiyama T, Otsubo H. Fast activity during EEG seizures in neonates. Epilepsy Res 2011; 97:162-9. [DOI: 10.1016/j.eplepsyres.2011.08.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2011] [Revised: 06/02/2011] [Accepted: 08/06/2011] [Indexed: 10/17/2022]
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Ekstrand JJ, Pouliot W, Scheerlinck P, Dudek FE. Lithium pilocarpine-induced status epilepticus in postnatal day 20 rats results in greater neuronal injury in ventral versus dorsal hippocampus. Neuroscience 2011; 192:699-707. [PMID: 21669257 DOI: 10.1016/j.neuroscience.2011.05.022] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2011] [Revised: 05/04/2011] [Accepted: 05/10/2011] [Indexed: 11/30/2022]
Abstract
Many quantitative animal studies examining the possible relationship between hippocampal neuronal loss and the development of epilepsy have examined only the dorsal hippocampus. The ventral hippocampus, however, represents the more homologous structure to the anterior hippocampus in humans, which is the area associated with the maximal damage in patients with temporal lobe epilepsy. This study tested the hypothesis that the ventral hippocampus has greater neuronal injury than the dorsal hippocampus in an animal model of chemoconvulsant-status epilepticus at postnatal day 20. Status epilepticus was induced in postnatal day 20 Sprague-Dawley rat pups with the chemoconvulsant lithium-pilocarpine and brain tissue was examined with Fluoro-Jade B. Horizontal sections (n=7) favoring a visualization of the ventral hippocampus showed marked Fluoro-Jade B staining in CA1, CA3, and hilar region. Coronal sections favoring a visualization of the dorsal hippocampus did not consistently show as robust a staining pattern in these regions. In coronal sections where both the dorsal and ventral hippocampus could be viewed, greater staining was always seen in ventral versus dorsal hippocampus. Quantitative analysis of cell counts demonstrated a significant difference between ventral and dorsal hippocampus in CA1 and CA3, but not hilus. These results demonstrate that in ventral hippocampus, lithium pilocarpine-induced status epilepticus consistently results in hippocampal neuronal injury in postnatal day 20 rats. This study shows the importance of including the ventral hippocampus in any analysis of seizure-induced hippocampal neuronal injury, and raises concerns about the accuracy of studies quantifying hippocampal neuronal loss when only the dorsal hippocampus is examined.
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Affiliation(s)
- J J Ekstrand
- Department of Pediatrics, University of Utah School of Medicine, Salt Lake City, UT 84108, USA.
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Davidson JO, Quaedackers JSLT, George SA, Gunn AJ, Bennet L. Maternal dexamethasone and EEG hyperactivity in preterm fetal sheep. J Physiol 2011; 589:3823-35. [PMID: 21646408 DOI: 10.1113/jphysiol.2011.212043] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Maternal treatment with synthetic corticosteroids such as dexamethasone (DEX)significantly reduces neonatal morbidity and mortality, but its effects on the fetal brain remain unclear. In this study we evaluated the effects of DEX on EEG activity in preterm fetal sheep. Ewes at 103 days gestation received two intramuscular injections of DEX (12 mg, n = 8) or saline vehicle (n = 7) 24 h apart. Fetal EEG activity was recorded from 6 h before until 120 h after the first injection (DEX-1). DEX-1 was associated with a marked transient rise in total EEG power, maximal at 12 h (P < 0.001), with a relative increase in delta and reduced theta, alpha and beta activity, resolving by 24 h. Continuous EEG records showed a shift to larger but less frequent transient waveforms (P < 0.001). Unexpectedly, evolving epileptiform activity, consistent with electrographic and clinical seizures, developed from 178 ± 44 min after DEX-1.Similar but smaller changes were seen after the second injection. Following the injections, total power returned to control values, but the proportion of alpha activity progressively increased vs. controls (P < 0.001), with reduced interburst interval duration and number (P < 0.001). No histological neural injury or microglial activation was seen. In summary, exposure to maternal dexamethasone was associated with dramatic, evolving low-frequency hyperactivity on fetal cortical EEG recordings, followed by sustained changes consistent with maturation of fetal sleep architecture. We postulate that these effects may contribute to improved neonatal outcomes.
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Affiliation(s)
- Joanne O Davidson
- Fetal Physiology and Neuroscience Group, Department of Physiology, The University of Auckland, Private Bag 92019, Auckland Mail Centre, Auckland 1142, New Zealand
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