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Li Z, Chen L, Xu C, Chen Z, Wang Y. Non-invasive sensory neuromodulation in epilepsy: Updates and future perspectives. Neurobiol Dis 2023; 179:106049. [PMID: 36813206 DOI: 10.1016/j.nbd.2023.106049] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2022] [Revised: 02/15/2023] [Accepted: 02/16/2023] [Indexed: 02/22/2023] Open
Abstract
Epilepsy, one of the most common neurological disorders, often is not well controlled by current pharmacological and surgical treatments. Sensory neuromodulation, including multi-sensory stimulation, auditory stimulation, olfactory stimulation, is a kind of novel noninvasive mind-body intervention and receives continued attention as complementary safe treatment of epilepsy. In this review, we summarize the recent advances of sensory neuromodulation, including enriched environment therapy, music therapy, olfactory therapy, other mind-body interventions, for the treatment of epilepsy based on the evidence from both clinical and preclinical studies. We also discuss their possible anti-epileptic mechanisms on neural circuit level and propose perspectives on possible research directions for future studies.
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Affiliation(s)
- Zhongxia Li
- Key Laboratory of Neuropharmacology and Translational Medicine of Zhejiang Province, School of Pharmaceutical Sciences, Zhejiang Chinese Medical University, Hangzhou, Zhejiang, China; Zhejiang Rehabilitation Medical Center Department, The Third Affiliated Hospital, Zhejiang Chinese Medical University, Hangzhou, China
| | - Liying Chen
- Department of Pharmacy, Sir Run Run Shaw Hospital, School of Medicine, Zhejiang University, Hangzhou, Zhejiang, China
| | - Cenglin Xu
- Key Laboratory of Neuropharmacology and Translational Medicine of Zhejiang Province, School of Pharmaceutical Sciences, Zhejiang Chinese Medical University, Hangzhou, Zhejiang, China
| | - Zhong Chen
- Key Laboratory of Neuropharmacology and Translational Medicine of Zhejiang Province, School of Pharmaceutical Sciences, Zhejiang Chinese Medical University, Hangzhou, Zhejiang, China
| | - Yi Wang
- Key Laboratory of Neuropharmacology and Translational Medicine of Zhejiang Province, School of Pharmaceutical Sciences, Zhejiang Chinese Medical University, Hangzhou, Zhejiang, China; Zhejiang Rehabilitation Medical Center Department, The Third Affiliated Hospital, Zhejiang Chinese Medical University, Hangzhou, China.
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Bäckström F, Ahl M, Wickham J, Ekdahl CT. Reduced epilepsy development in synapsin 2 knockout mice with autistic behavior following early systemic treatment with interleukin-6 receptor antibody. Epilepsy Res 2023; 191:107114. [PMID: 36870094 DOI: 10.1016/j.eplepsyres.2023.107114] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2022] [Revised: 02/09/2023] [Accepted: 02/23/2023] [Indexed: 02/27/2023]
Abstract
BACKGROUND Individuals with autism spectrum disorder (ASD) have an increased risk of developing epilepsy. Both ASD and epilepsy have been associated with increased levels of immune factors in the blood, including the proinflammatory cytokine interleukin 6 (IL-6). Mice lacking the synapsin 2 gene (Syn2 KO) exhibit ASD-like behavior and develop epileptic seizures. Their brains display neuroinflammatory changes including elevated IL-6 levels. We aimed to investigate the effect of systemic IL-6 receptor antibody (IL-6R ab) treatment on seizure development and frequency in Syn2 KO mice. MATERIAL AND METHODS Weekly systemic (i.p.) injections of IL-6R ab or saline were given to Syn2 KO mice starting either early in life at 1 month of age, before seizure debut or at 3 months of age, directly after seizure debut and continued for 4 or 2 months, respectively. Seizures were provoked by handling the mice three times per week. The neuroinflammatory response and synaptic protein levels in the brain were determined by ELISA, immunohistochemistry and western blots. In an additional group of Syn2 KO mice, with IL-6R ab treatment early in life, ASD-related behavioral tests including social interaction and repetitive self-grooming, as well as cognitive memory and depressive-/anxiety-like tests, and actigraphy measurements of circadian sleep-awake rhythm were analyzed. RESULTS The IL-6R ab treatment reduced seizure development and frequency in Syn2 KO mice when initiated before, but not after, seizure debut. However, early treatment did not reverse the neuroinflammatory response or the imbalance in synaptic protein levels in the brain previously reported in Syn2 KO mice. The treatment did not affect social interaction, performance in memory, depressive-/anxiety-like tests or the sleep-awake rhythm of Syn2 KO mice. CONCLUSION These findings suggest the involvement of IL-6 receptor signaling during epilepsy development in Syn2 KO mice, without significant alterations of the immune reaction in the brain, and independently of cognitive performance, mood and circadian sleep-awake rhythm.
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Affiliation(s)
- Filip Bäckström
- Inflammation and Stem Cell Therapy Group, Division of Clinical Neurophysiology, Department of Clinical Sciences, Lund University, Lund, Sweden; Lund Epilepsy Center, Department of Clinical Sciences, Lund University, Lund, Sweden; Translational Neurogenetics Unit, Department of Experimental Medical Science, Lund University, Lund, Sweden
| | - Matilda Ahl
- Inflammation and Stem Cell Therapy Group, Division of Clinical Neurophysiology, Department of Clinical Sciences, Lund University, Lund, Sweden; Lund Epilepsy Center, Department of Clinical Sciences, Lund University, Lund, Sweden
| | - Jenny Wickham
- Inflammation and Stem Cell Therapy Group, Division of Clinical Neurophysiology, Department of Clinical Sciences, Lund University, Lund, Sweden; Lund Epilepsy Center, Department of Clinical Sciences, Lund University, Lund, Sweden
| | - Christine T Ekdahl
- Inflammation and Stem Cell Therapy Group, Division of Clinical Neurophysiology, Department of Clinical Sciences, Lund University, Lund, Sweden; Lund Epilepsy Center, Department of Clinical Sciences, Lund University, Lund, Sweden.
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3
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Sarkisova K, van Luijtelaar G. The impact of early-life environment on absence epilepsy and neuropsychiatric comorbidities. IBRO Neurosci Rep 2022; 13:436-468. [PMID: 36386598 PMCID: PMC9649966 DOI: 10.1016/j.ibneur.2022.10.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2022] [Revised: 10/30/2022] [Accepted: 10/31/2022] [Indexed: 11/11/2022] Open
Abstract
This review discusses the long-term effects of early-life environment on epileptogenesis, epilepsy, and neuropsychiatric comorbidities with an emphasis on the absence epilepsy. The WAG/Rij rat strain is a well-validated genetic model of absence epilepsy with mild depression-like (dysthymia) comorbidity. Although pathologic phenotype in WAG/Rij rats is genetically determined, convincing evidence presented in this review suggests that the absence epilepsy and depression-like comorbidity in WAG/Rij rats may be governed by early-life events, such as prenatal drug exposure, early-life stress, neonatal maternal separation, neonatal handling, maternal care, environmental enrichment, neonatal sensory impairments, neonatal tactile stimulation, and maternal diet. The data, as presented here, indicate that some early environmental events can promote and accelerate the development of absence seizures and their neuropsychiatric comorbidities, while others may exert anti-epileptogenic and disease-modifying effects. The early environment can lead to phenotypic alterations in offspring due to epigenetic modifications of gene expression, which may have maladaptive consequences or represent a therapeutic value. Targeting DNA methylation with a maternal methyl-enriched diet during the perinatal period appears to be a new preventive epigenetic anti-absence therapy. A number of caveats related to the maternal methyl-enriched diet and prospects for future research are discussed.
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Affiliation(s)
- Karine Sarkisova
- Institute of Higher Nervous Activity and Neurophysiology of Russian Academy of Sciences, Butlerova str. 5a, Moscow 117485, Russia
| | - Gilles van Luijtelaar
- Donders Institute for Brain, Cognition, and Behavior, Donders Center for Cognition, Radboud University, Nijmegen, PO Box 9104, 6500 HE Nijmegen, the Netherlands
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Impact of Stress on Epilepsy: Focus on Neuroinflammation-A Mini Review. Int J Mol Sci 2021; 22:ijms22084061. [PMID: 33920037 PMCID: PMC8071059 DOI: 10.3390/ijms22084061] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Revised: 04/11/2021] [Accepted: 04/12/2021] [Indexed: 02/08/2023] Open
Abstract
Epilepsy, one of the most common neurological disorders worldwide, is characterized by recurrent seizures and subsequent brain damage. Despite strong evidence supporting a deleterious impact on seizure occurrence and outcome severity, stress is an overlooked component in people with epilepsy. With regard to stressor duration and timing, acute stress can be protective in epileptogenesis, while chronic stress often promotes seizure occurrence in epilepsy patients. Preclinical research suggests that chronic stress promotes neuroinflammation and leads to a depressive state. Depression is the most common psychiatric comorbidity in people with epilepsy, resulting in a poor quality of life. Here, we summarize studies investigating acute and chronic stress as a seizure trigger and an important factor that worsens epilepsy outcomes and psychiatric comorbidities. Mechanistic insight into the impact of stress on epilepsy may create a window of opportunity for future interventions targeting neuroinflammation-related disorders.
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Akyuz E, Eroglu E. Envisioning the crosstalk between environmental enrichment and epilepsy: A novel perspective. Epilepsy Behav 2021; 115:107660. [PMID: 33328107 DOI: 10.1016/j.yebeh.2020.107660] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/01/2020] [Revised: 11/16/2020] [Accepted: 11/21/2020] [Indexed: 12/31/2022]
Abstract
Epilepsies are a diverse group of neurological disorders characterized by an unprovoked seizure and a brain that has an enduring predisposition to seizures. The lack of disease-modifying treatment strategies against the same has led to the exploration of novel treatment strategies that could halt epileptic seizures. In this regard, environmental enrichment (EE) has gained increased attention in recent days. EE modulates the effects of interactions between the genes and the environment on the structure and function of the brain. EE therapy can improve seizure-related symptoms in neurological diseases such as epilepsy. EE therapy can have a significant effect on cognitive disorders such as learning and memory impairments associated with seizures. EE therapy in epileptic hippocampus tissue can improve seizure-related symptoms by inducing enhanced neurogenesis and neuroprotective mechanisms. In this context, the efficiency of EE is regulated in the epilepsy by the brain-derived neurotrophic factor (BDNF)/extracellular signal-regulated kinase (ERK) signaling pathway regulated by extracellular signaling. Herein, we provide experimental evidence supporting the beneficial effects of EE in epileptic seizures and its underlying mechanism.
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Affiliation(s)
- Enes Akyuz
- Yozgat Bozok University, Medical School, Department of Biophysics, 66100 Yozgat, Turkey.
| | - Ece Eroglu
- Yozgat Bozok University, Medical School, 66100 Yozgat, Turkey.
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Zeraati M, Najdi N, Mosaferi B, Salari AA. Environmental enrichment alters neurobehavioral development following maternal immune activation in mice offspring with epilepsy. Behav Brain Res 2020; 399:112998. [PMID: 33197458 DOI: 10.1016/j.bbr.2020.112998] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2020] [Revised: 10/29/2020] [Accepted: 10/30/2020] [Indexed: 12/17/2022]
Abstract
Epilepsy is a chronic brain disease affecting millions of people worldwide. Anxiety-related disorders and cognitive deficits are common in patients with epilepsy. Previous studies have shown that maternal infection/immune activation renders children more vulnerable to neurological disorders later in life. Environmental enrichment has been suggested to improve seizures, anxiety, and cognitive impairment in animal models. The present study aimed to explore the effects of environmental enrichment on seizure scores, anxiety-like behavior, and cognitive deficits following maternal immune activation in offspring with epilepsy. Pregnant mice were treated with lipopolysaccharides-(LPS) or vehicle, and offspring were housed in normal or enriched environments during early adolescence to adulthood. To induce epilepsy, adult male and female offspring were treated with Pentylenetetrazol-(PTZ), and then anxiety-like behavior and cognitive functions were assessed. Tumor-necrosis-factor (TNF)-α and interleukin (IL) 10 were measured in the hippocampus of offspring. Maternal immune activation sex-dependently increased seizure scores in PTZ-treated offspring. Significant increases in anxiety-like behavior, cognitive impairment, and hippocampal TNF-α and IL-10 were also found following maternal immune activation in PTZ-treated offspring. However, there was no sex difference in these behavioral abnormalities in offspring. Environmental enrichment reversed the effects of maternal immune activation on behavioral and inflammatory parameters in PTZ-treated offspring. Overall, the present findings highlight the adverse effects of prenatal maternal immune activation on seizure susceptibility and psychiatric comorbidities in offspring. This study suggests that environmental enrichment may be used as a potential treatment approach for behavioral abnormalities following maternal immune activation in PTZ-treated offspring.
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Affiliation(s)
- Maryam Zeraati
- Physiology and Pharmacology Department, Faculty of Medicine, Alborz University of Medical Sciences, Karaj, Alborz, Iran
| | - Nazila Najdi
- Department of Obstetrics and Gynecology, School of Medicine, Arak University of Medical Sciences, Arak, Iran
| | - Belal Mosaferi
- Department of Basic Sciences, School of Nursing and Midwifery, Maragheh University of Medical Sciences, Maragheh, Iran
| | - Ali-Akbar Salari
- Salari Institute of Cognitive and Behavioral Disorders (SICBD), Karaj, Alborz, Iran.
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Gubert C, Hannan AJ. Environmental enrichment as an experience-dependent modulator of social plasticity and cognition. Brain Res 2019; 1717:1-14. [DOI: 10.1016/j.brainres.2019.03.033] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2018] [Revised: 03/11/2019] [Accepted: 03/27/2019] [Indexed: 12/14/2022]
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Llorens-Martín M. Exercising New Neurons to Vanquish Alzheimer Disease. Brain Plast 2018; 4:111-126. [PMID: 30564550 PMCID: PMC6296267 DOI: 10.3233/bpl-180065] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/21/2018] [Indexed: 02/07/2023] Open
Abstract
Alzheimer disease (AD) is the most common type of dementia in individuals over 65 years of age. The neuropathological hallmarks of the condition are Tau neurofibrillary tangles and Amyloid-β senile plaques. Moreover, certain susceptible regions of the brain experience a generalized lack of neural plasticity and marked synaptic alterations during the progression of this as yet incurable disease. One of these regions, the hippocampus, is characterized by the continuous addition of new neurons throughout life. This phenomenon, named adult hippocampal neurogenesis (AHN), provides a potentially endless source of new synaptic elements that increase the complexity and plasticity of the hippocampal circuitry. Numerous lines of evidence show that physical activity and environmental enrichment (EE) are among the most potent positive regulators of AHN. Given that neural plasticity is markedly decreased in many neurodegenerative diseases, the therapeutic potential of making certain lifestyle changes, such as increasing physical activity, is being recognised in several non-pharmacologic strategies seeking to slow down or prevent the progression of these diseases. This review article summarizes current evidence supporting the putative therapeutic potential of EE and physical exercise to increase AHN and hippocampal plasticity both under physiological and pathological circumstances, with a special emphasis on neurodegenerative diseases and AD.
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Affiliation(s)
- María Llorens-Martín
- Department of Molecular Neuropathology, Centro de Biología Molecular “Severo Ochoa”, CBMSO, CSIC-UAM, Madrid, Spain
- Center for Networked Biomedical Research on Neurodegenerative Diseases CIBERNED, Madrid, Spain
- Department of Molecular Biology, Faculty of Sciences, Universidad Autónoma de Madrid, Madrid, Spain
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Environmental enrichment alleviates cognitive and behavioral impairments in EL mice. Epilepsy Behav 2018; 85:227-233. [PMID: 30032812 DOI: 10.1016/j.yebeh.2018.06.016] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/08/2018] [Revised: 06/01/2018] [Accepted: 06/01/2018] [Indexed: 01/17/2023]
Abstract
Epilepsy in children is occasionally associated with comorbidities, such as cognitive impairment, behavioral disturbances, and social deficits. These neurobehavioral comorbidities are closely related to environmental factors and the severity of the seizures. Previous studies show that environmental enrichment has a beneficial effect in animal models of temporal lobe epilepsy following systemic chemoconvulsant administration. However, the effect of environmental enrichment on behavioral impairments in the EL mouse, a genetic model of human idiopathic epilepsy, remains unknown. In the present study, we examined the effect of environmental enrichment on cognitive and behavioral impairments in this murine model. The EL mice, under standard laboratory conditions, exhibited impairments in spatial memory in the Morris water maze test, hyperactivity and impaired habituation in the open-field test, and a deficit in social novelty preference in the three-chamber social approach test, compared with control DDY mice, a genetically related nonepileptic strain. These impairments in EL mice were ameliorated by exposure to an enriched environment. These findings suggest that environmental enrichment effectively ameliorates cognitive and behavioral deficits in EL mice.
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10
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Wang K, Chen X, Liu J, Zou LP, Feng W, Cai L, Wu X, Chen SY. Embryonic exposure to ethanol increases the susceptibility of larval zebrafish to chemically induced seizures. Sci Rep 2018; 8:1845. [PMID: 29382872 PMCID: PMC5789864 DOI: 10.1038/s41598-018-20288-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2017] [Accepted: 01/16/2018] [Indexed: 11/27/2022] Open
Abstract
Prenatal ethanol exposure is known to cause neurodevelopmental disorders. While high prevalence of epilepsy is observed among the children whose mothers abused alcohol during pregnancy, the results from animal studies are conflicting. Here, we investigated whether embryonic exposure to ethanol can increase the susceptibility to pentylenetetrazole (PTZ)-induced seizures in larval zebrafish. Embryos at 3 hours post-fertilization (hpf) were exposed to ethanol at the concentrations ranging from 0.25% to 1% for 21 hours. Control and ethanol-exposed larvae were challenged with PTZ at 7 days post-fertilization (dpf) at the concentrations of 2.5, 5 or 15 mM. The seizure behavior of larvae was recorded and analyzed using EthoVision XT 11. We found that embryonic ethanol exposure increased the percentage of larvae exhibiting typical stage II and III seizure and resulted in a significant reduction in stage I, II and III seizure latency in an ethanol concentration-dependent manner. Embryonic exposure to ethanol also significantly increased the severity of PTZ-induced seizures in larvae, as demonstrated by increased total distance traveled and the duration of mobility. This is the first demonstration that ethanol exposure during early embryonic stage can reduce the threshold for chemically induced seizures and increase the severity of seizure behavior in larval fish.
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Affiliation(s)
- Keling Wang
- Department of Pharmacology and Toxicology, Alcohol Research Center, University of Louisville Health Science Center, Louisville, KY, 40292, USA.,Department of Pediatrics, Chinese PLA General Hospital, Beijing, 100853, China
| | - Xiaopan Chen
- Department of Pharmacology and Toxicology, Alcohol Research Center, University of Louisville Health Science Center, Louisville, KY, 40292, USA.,Department of Reproductive Endocrinology, Zhejiang Provincial People's Hospital, 158 Shangtang Road, Hangzhou, Zhejiang, 310014, China
| | - Jie Liu
- Department of Pharmacology and Toxicology, Alcohol Research Center, University of Louisville Health Science Center, Louisville, KY, 40292, USA
| | - Li-Ping Zou
- Department of Pediatrics, Chinese PLA General Hospital, Beijing, 100853, China
| | - Wenke Feng
- Department of Pharmacology and Toxicology, Alcohol Research Center, University of Louisville Health Science Center, Louisville, KY, 40292, USA.,Department of Medicine, University of Louisville, Louisville, KY, 40292, USA
| | - Lu Cai
- Pediatric Research Institute, Department of Pediatrics, University of Louisville, Louisville, KY, 40202, USA
| | - Xiaoyang Wu
- Ben May Department for Cancer Research, University of Chicago, Chicago, IL, 60637, USA
| | - Shao-Yu Chen
- Department of Pharmacology and Toxicology, Alcohol Research Center, University of Louisville Health Science Center, Louisville, KY, 40292, USA.
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11
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Vrinda M, Sasidharan A, Aparna S, Srikumar BN, Kutty BM, Shankaranarayana Rao BS. Enriched environment attenuates behavioral seizures and depression in chronic temporal lobe epilepsy. Epilepsia 2017; 58:1148-1158. [PMID: 28480502 DOI: 10.1111/epi.13767] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/27/2017] [Indexed: 01/30/2023]
Abstract
OBJECTIVE Temporal lobe epilepsy (TLE) is commonly associated with depression, anxiety, and cognitive impairment. Despite significant progress in our understanding of the pathophysiology of TLE, it remains the most common form of refractory epilepsy. Enriched environment (EE) has a beneficial effect in many neuropsychiatric disorders. However, the effect of EE on cognitive changes in chronic TLE has not been evaluated. Accordingly, the present study evaluated the effects of EE on chronic epilepsy-induced alterations in cognitive functions, electrophysiology, and cellular changes in the hippocampus. METHODS Status epilepticus (SE) was induced in 2-month-old male Wistar rats with lithium and pilocarpine. Six weeks' post SE, epileptic rats were either housed in their respective home cages or in an enrichment cage (6 h/day) for 14 days. Seizure behavior was video-monitored 2 weeks before and during exposure to EE. Depression-like behavior, anxiety-like behavior, and spatial learning and memory were assessed using the sucrose preference test (SPT), elevated plus maze (EPM), and Morris water maze (MWM), respectively. Delta and theta power in the CA1 region of hippocampus was assessed from recordings of local field potentials (LFPs). Cellular changes in hippocampus were assessed by histochemistry followed by unbiased stereologic analysis. RESULTS EE significantly reduced seizure episodes and seizure duration in epileptic rats. In addition, EE alleviated depression and hyperactivity, and restored delta and theta power of LFP in the hippocampal CA1 region. However, EE neither ameliorated epilepsy-induced spatial learning and memory deficits nor restored cell density in hippocampus. SIGNIFICANCE This is the first study that evaluates the role of EE in a chronic TLE model, where rats were exposed to EE after occurrence of spontaneous recurrent seizures (SRS). Given that 30% of TLE patients are refractory to drug treatment, therapeutic strategies that utilize components of EE could be designed to alleviate seizures and psychiatric comorbidities associated with TLE.
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Affiliation(s)
- Marigowda Vrinda
- Department of Neurophysiology, National Institute of Mental Health and Neuro Sciences, Bengaluru, India.,Axxonet Brain Research Laboratory, Axxonet System Technologies Pvt. Ltd., Bengaluru, 560 029, India
| | - Arun Sasidharan
- Department of Neurophysiology, National Institute of Mental Health and Neuro Sciences, Bengaluru, India.,Axxonet Brain Research Laboratory, Axxonet System Technologies Pvt. Ltd., Bengaluru, 560 029, India
| | - Sahajan Aparna
- Department of Neurophysiology, National Institute of Mental Health and Neuro Sciences, Bengaluru, India
| | - Bettadapura N Srikumar
- Department of Neurophysiology, National Institute of Mental Health and Neuro Sciences, Bengaluru, India
| | - Bindu M Kutty
- Department of Neurophysiology, National Institute of Mental Health and Neuro Sciences, Bengaluru, India
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Dezsi G, Ozturk E, Salzberg MR, Morris M, O'Brien TJ, Jones NC. Environmental enrichment imparts disease-modifying and transgenerational effects on genetically-determined epilepsy and anxiety. Neurobiol Dis 2016; 93:129-36. [PMID: 27185593 DOI: 10.1016/j.nbd.2016.05.005] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2016] [Revised: 05/02/2016] [Accepted: 05/08/2016] [Indexed: 10/21/2022] Open
Abstract
INTRODUCTION The absence epilepsies are presumed to be caused by genetic factors, but the influence of environmental exposures on epilepsy development and severity, and whether this influence is transmitted to subsequent generations, is not well known. We assessed the effects of environmental enrichment on epilepsy and anxiety outcomes in multiple generations of GAERS - a genetic rat model of absence epilepsy that manifests comorbid elevated anxiety-like behaviour. METHODS GAERS were exposed to environmental enrichment or standard housing beginning either prior to, or after epilepsy onset, and underwent EEG recordings and anxiety testing. Then, we exposed male GAERS to early enrichment or standard housing and generated F1 progeny, which also underwent EEG recordings. Hippocampal CRH mRNA expression and DNA methylation were assessed using RT-PCR and pyrosequencing, respectively. RESULTS Early environmental enrichment delayed the onset of epilepsy in GAERS, and resulted in fewer seizures in adulthood, compared with standard housed GAERS. Enrichment also reduced the frequency of seizures when initiated in adulthood. Anxiety levels were reduced by enrichment, and these anti-epileptogenic and anxiolytic effects were heritable into the next generation. We also found reduced expression of CRH mRNA in GAERS exposed to enrichment, but this was not due to changes in DNA methylation. CONCLUSIONS Environmental enrichment produces disease-modifying effects on genetically determined absence epilepsy and anxiety, and these beneficial effects are transferable to the subsequent generation. Reduced CRH expression was associated with these phenotypic improvements. Environmental stimulation holds promise as a naturalistic therapy for genetically determined epilepsy which may benefit subsequent generations.
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Affiliation(s)
- Gabi Dezsi
- Department of Medicine (Royal Melbourne Hospital), University of Melbourne, Melbourne, Victoria, Australia
| | - Ezgi Ozturk
- Department of Medicine (Royal Melbourne Hospital), University of Melbourne, Melbourne, Victoria, Australia
| | - Michael R Salzberg
- Department of Medicine (Royal Melbourne Hospital), University of Melbourne, Melbourne, Victoria, Australia; Department of Psychiatry, St Vincent's Hospital, Melbourne, Victoria, Australia
| | - Margaret Morris
- Department of Pharmacology and Physiology, University of New South Wales, Sydney, New South Wales, Australia
| | - Terence J O'Brien
- Department of Medicine (Royal Melbourne Hospital), University of Melbourne, Melbourne, Victoria, Australia
| | - Nigel C Jones
- Department of Medicine (Royal Melbourne Hospital), University of Melbourne, Melbourne, Victoria, Australia.
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Yang M, Ozturk E, Salzberg MR, Rees S, Morris M, O'Brien TJ, Jones NC. Environmental enrichment delays limbic epileptogenesis and restricts pathologic synaptic plasticity. Epilepsia 2016; 57:484-94. [DOI: 10.1111/epi.13299] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/30/2015] [Indexed: 12/30/2022]
Affiliation(s)
- Meng Yang
- Department of Medicine (Royal Melbourne Hospital); Melbourne Brain Centre; The University of Melbourne; Melbourne Victoria Australia
| | - Ezgi Ozturk
- Department of Medicine (Royal Melbourne Hospital); Melbourne Brain Centre; The University of Melbourne; Melbourne Victoria Australia
| | - Michael R. Salzberg
- Department of Medicine (Royal Melbourne Hospital); Melbourne Brain Centre; The University of Melbourne; Melbourne Victoria Australia
- Department of Psychiatry; St Vincent's Hospital; Melbourne Victoria Australia
| | - Sandra Rees
- Department of Anatomy and Neuroscience; University of Melbourne; Melbourne Victoria Australia
| | - Margaret Morris
- Department of Pharmacology; UNSW Australia; Sydney New South Wales Australia
| | - Terence J. O'Brien
- Department of Medicine (Royal Melbourne Hospital); Melbourne Brain Centre; The University of Melbourne; Melbourne Victoria Australia
| | - Nigel C. Jones
- Department of Medicine (Royal Melbourne Hospital); Melbourne Brain Centre; The University of Melbourne; Melbourne Victoria Australia
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Bezzina C, Verret L, Halley H, Dahan L, Rampon C. Environmental enrichment does not influence hypersynchronous network activity in the Tg2576 mouse model of Alzheimer's disease. Front Aging Neurosci 2015; 7:178. [PMID: 26441640 PMCID: PMC4585132 DOI: 10.3389/fnagi.2015.00178] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2015] [Accepted: 09/03/2015] [Indexed: 11/24/2022] Open
Abstract
The cognitive reserve hypothesis claims that the brain can overcome pathology by reinforcing preexistent processes or by developing alternative cognitive strategies. Epidemiological studies have revealed that this reserve can be built throughout life experiences as education or leisure activities. We previously showed that an early transient environmental enrichment (EE) durably improves memory performances in the Tg2576 mouse model of Alzheimer’s disease (AD). Recently, we evidenced a hypersynchronous brain network activity in young adult Tg2576 mice. As aberrant oscillatory activity can contribute to memory deficits, we wondered whether the long-lasting memory improvements observed after EE were associated with a reduction of neuronal network hypersynchrony. Thus, we exposed non-transgenic (NTg) and Tg2576 mice to standard or enriched housing conditions for 10 weeks, starting at 3 months of age. Two weeks after EE period, Tg2576 mice presented similar seizure susceptibility to a GABA receptor antagonist. Immediately after and 2 weeks after this enrichment period, standard and enriched-housed Tg2576 mice did not differ with regards to the frequency of interictal spikes on their electroencephalographic (EEG) recordings. Thus, the long-lasting effect of this EE protocol on memory capacities in Tg2576 mice is not mediated by a reduction of their cerebral aberrant neuronal activity at early ages.
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Affiliation(s)
- Charlotte Bezzina
- UMR5169 CNRS, Centre de Recherches sur la Cognition Animale, Université de Toulouse, Université Paul Sabatier Toulouse, France ; CNRS, Centre de Recherches sur la Cognition Animale Toulouse, France
| | - Laure Verret
- UMR5169 CNRS, Centre de Recherches sur la Cognition Animale, Université de Toulouse, Université Paul Sabatier Toulouse, France ; CNRS, Centre de Recherches sur la Cognition Animale Toulouse, France
| | - Hélène Halley
- UMR5169 CNRS, Centre de Recherches sur la Cognition Animale, Université de Toulouse, Université Paul Sabatier Toulouse, France ; CNRS, Centre de Recherches sur la Cognition Animale Toulouse, France
| | - Lionel Dahan
- UMR5169 CNRS, Centre de Recherches sur la Cognition Animale, Université de Toulouse, Université Paul Sabatier Toulouse, France ; CNRS, Centre de Recherches sur la Cognition Animale Toulouse, France
| | - Claire Rampon
- UMR5169 CNRS, Centre de Recherches sur la Cognition Animale, Université de Toulouse, Université Paul Sabatier Toulouse, France ; CNRS, Centre de Recherches sur la Cognition Animale Toulouse, France
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15
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Kotloski RJ, Sutula TP. Environmental enrichment: evidence for an unexpected therapeutic influence. Exp Neurol 2014; 264:121-6. [PMID: 25483395 DOI: 10.1016/j.expneurol.2014.11.012] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2014] [Revised: 11/20/2014] [Accepted: 11/25/2014] [Indexed: 12/13/2022]
Abstract
Environmental enrichment produces wide-ranging effects in the brain at molecular, cellular, network, and behavioral levels. The changes in neuronal plasticity are driven by changes in neurotransmitters, neurotrophic factors, neuronal morphology, neurogenesis, network properties of the brain, and behavioral correlates of learning and memory. Exposure to an enriched environment has also demonstrated intriguing possibilities for treatment of a variety of neurodegenerative diseases including Huntington's disease, Alzheimer's disease, and Parkinson's disease. The effect of environmental enrichment in epilepsy, a neurodegenerative disorder with pathological neuronal plasticity, is of considerable interest. Recent reports of the effect of environmental enrichment in the Bassoon mutant mouse, a genetic model of early onset epilepsy, provides a significant addition to the literature in this area.
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Affiliation(s)
- Robert J Kotloski
- Department of Neurology, University of Wisconsin, Madison, WI 53705, USA; Department of Neurology, William S Middleton Veterans Memorial Hospital, Madison, WI 53705, USA
| | - Thomas P Sutula
- Department of Neurology, University of Wisconsin, Madison, WI 53705, USA.
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16
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Alwis DS, Rajan R. Environmental enrichment and the sensory brain: the role of enrichment in remediating brain injury. Front Syst Neurosci 2014; 8:156. [PMID: 25228861 PMCID: PMC4151031 DOI: 10.3389/fnsys.2014.00156] [Citation(s) in RCA: 73] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2014] [Accepted: 08/12/2014] [Indexed: 01/08/2023] Open
Abstract
The brain's life-long capacity for experience-dependent plasticity allows adaptation to new environments or to changes in the environment, and to changes in internal brain states such as occurs in brain damage. Since the initial discovery by Hebb (1947) that environmental enrichment (EE) was able to confer improvements in cognitive behavior, EE has been investigated as a powerful form of experience-dependent plasticity. Animal studies have shown that exposure to EE results in a number of molecular and morphological alterations, which are thought to underpin changes in neuronal function and ultimately, behavior. These consequences of EE make it ideally suited for investigation into its use as a potential therapy after neurological disorders, such as traumatic brain injury (TBI). In this review, we aim to first briefly discuss the effects of EE on behavior and neuronal function, followed by a review of the underlying molecular and structural changes that account for EE-dependent plasticity in the normal (uninjured) adult brain. We then extend this review to specifically address the role of EE in the treatment of experimental TBI, where we will discuss the demonstrated sensorimotor and cognitive benefits associated with exposure to EE, and their possible mechanisms. Finally, we will explore the use of EE-based rehabilitation in the treatment of human TBI patients, highlighting the remaining questions regarding the effects of EE.
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Affiliation(s)
- Dasuni S Alwis
- Department of Physiology, Monash University Clayton, VIC, Australia
| | - Ramesh Rajan
- Department of Physiology, Monash University Clayton, VIC, Australia
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17
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van Campen JS, Jansen FE, de Graan PNE, Braun KPJ, Joels M. Early life stress in epilepsy: a seizure precipitant and risk factor for epileptogenesis. Epilepsy Behav 2014; 38:160-71. [PMID: 24144618 DOI: 10.1016/j.yebeh.2013.09.029] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/04/2013] [Revised: 09/17/2013] [Accepted: 09/19/2013] [Indexed: 10/26/2022]
Abstract
Stress can influence epilepsy in multiple ways. A relation between stress and seizures is often experienced by patients with epilepsy. Numerous questionnaire and diary studies have shown that stress is the most often reported seizure-precipitating factor in epilepsy. Acute stress can provoke epileptic seizures, and chronic stress increases seizure frequency. In addition to its effects on seizure susceptibility in patients with epilepsy, stress might also increase the risk of epilepsy development, especially when the stressors are severe, prolonged, or experienced early in life. Although the latter has not been fully resolved in humans, various preclinical epilepsy models have shown increased seizure susceptibility in naïve rodents after prenatal and early postnatal stress exposure. In the current review, we first provide an overview of the effects of stress on the brain. Thereafter, we discuss human as well as preclinical studies evaluating the relation between stress, epileptic seizures, and epileptogenesis, focusing on the epileptogenic effects of early life stress. Increased knowledge on the interaction between early life stress, seizures, and epileptogenesis could improve patient care and provide a basis for new treatment strategies for epilepsy.
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Affiliation(s)
- Jolien S van Campen
- Department of Pediatric Neurology, Brain Center Rudolf Magnus, University Medical Center Utrecht, The Netherlands; Department of Neuroscience & Pharmacology, Brain Center Rudolf Magnus, University Medical Center Utrecht, The Netherlands.
| | - Floor E Jansen
- Department of Pediatric Neurology, Brain Center Rudolf Magnus, University Medical Center Utrecht, The Netherlands
| | - Pierre N E de Graan
- Department of Neuroscience & Pharmacology, Brain Center Rudolf Magnus, University Medical Center Utrecht, The Netherlands
| | - Kees P J Braun
- Department of Pediatric Neurology, Brain Center Rudolf Magnus, University Medical Center Utrecht, The Netherlands
| | - Marian Joels
- Department of Neuroscience & Pharmacology, Brain Center Rudolf Magnus, University Medical Center Utrecht, The Netherlands
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18
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Abstract
Trauma in childhood is a psychosocial, medical, and public policy problem with serious consequences for its victims and for society. Chronic interpersonal violence in children is common worldwide. Developmental traumatology, the systemic investigation of the psychiatric and psychobiological effects of chronic overwhelming stress on the developing child, provides a framework and principles when empirically examining the neurobiological effects of pediatric trauma. This article focuses on peer-reviewed literature on the neurobiological sequelae of childhood trauma in children and in adults with histories of childhood trauma.
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Affiliation(s)
- Michael D De Bellis
- Healthy Childhood Brain Development and Developmental Traumatology Research Program, Department of Psychiatry and Behavioral Sciences, Duke University Medical Center, Box 104360, Durham, NC 27710, USA.
| | - Abigail Zisk
- Healthy Childhood Brain Development and Developmental Traumatology Research Program, Department of Psychiatry and Behavioral Sciences, Duke University Medical Center, Box 104360, Durham, NC 27710, USA
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19
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Korgan AC, Green AD, Perrot TS, Esser MJ. Limbic system activation is affected by prenatal predator exposure and postnatal environmental enrichment and further moderated by dam and sex. Behav Brain Res 2013; 259:106-18. [PMID: 24185030 DOI: 10.1016/j.bbr.2013.10.037] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2013] [Revised: 10/18/2013] [Accepted: 10/24/2013] [Indexed: 02/07/2023]
Abstract
Epilepsy is a relatively common and chronic neurological condition, affecting 1-2% of the population. However, understanding of the underlying pathophysiology remains incomplete. To identify potential factors in the early environment that may increase the risk for experiencing seizures, maternal stress and environmental enrichment (EE) were utilized. Pregnant Long-Evans rats were exposed to an ethologically relevant predator stress (PS) and maternal glucocorticoid (GC) response was assessed across the exposure period. At birth, litters were divided into standard care (SC) and EE groups until postnatal day 14 (PD14) when a model of febrile convulsions was used to determine seizure susceptibility of the various groups. Pup brains were then processed for immunohistochemical detection of FosB from several structures in the limbic system as a measure of neuronal activation. Maternal PS-induced GC levels were elevated early in the exposure period, and pup birth weights, in both sexes, were lower in litters from dams exposed to PS. Seizure scores at PD14 were highly individualized and litter dependent, suggesting a dam-dependent and variable effect of controlled pre- and postnatal environmental factors. Further, analysis of FosB-immunoreactive (-ir) patterns revealed an activity dependent distribution, reflecting individual seizure susceptibility. EE had a varying effect on FosB-ir that was dependent on region. In the hippocampus FosB-ir levels were greater in the EE groups while extra-hippocampal regions showed lower levels of FosB-ir. Our results support the concept that pre- and postnatal environmental influences affect fetal programming and neurodevelopment of processes that could underlie seizure susceptibility, but that the magnitude of these effects appears to be dam- or litter-dependent.
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Affiliation(s)
- Austin C Korgan
- Department of Psychology and Neuroscience, Dalhousie University, Halifax, NS, Canada
| | - Amanda D Green
- Department of Psychology and Neuroscience, Dalhousie University, Halifax, NS, Canada
| | - Tara S Perrot
- Department of Psychology and Neuroscience, Dalhousie University, Halifax, NS, Canada.
| | - Michael J Esser
- Department of Psychology and Neuroscience, Dalhousie University, Halifax, NS, Canada; Departments of Pediatrics and Pharmacology, IWK Health Care Centre, Halifax, NS, Canada
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20
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Etholm L, Bahonjic E, Heggelund P. Sensitive and critical periods in the development of handling induced seizures in mice lacking synapsins: differences between synapsin I and synapsin II knockouts. Exp Neurol 2013; 247:59-65. [PMID: 23570901 DOI: 10.1016/j.expneurol.2013.03.025] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2013] [Revised: 03/22/2013] [Accepted: 03/29/2013] [Indexed: 01/14/2023]
Abstract
Mice lacking either synapsin I or synapsin II develop handling induced seizures from around two months of age. In mice lacking synapsin I (synapsin 1 knock-out mice, Syn1KO mice) such seizures can either consist of mild myoclonic jerks or of fully developed generalized tonic-clonic seizures, and the two seizure types are quite evenly distributed. In mice lacking synapsin II (synapsin 2 knock-out mice, Syn2KO mice) all seizures are in the form of generalized tonic-clonic seizures. Through the use of specialized animal rearing procedures whereby human-animal interaction was minimized (minimal handling procedures), this study investigated effects of handling also prior to the emergence of actual seizures. The effect of minimal handling procedures was significant in both genotypes, but most pronounced in Syn1KO mice. In this genotype, minimal handling reduced the frequency of mild seizures, and completely eliminated generalized tonic-clonic seizures when the animals were tested with regular handling at 4 1/2 months of age. Neither seizure frequency nor generalized tonic-clonic seizures could be re-established through regular handling from 4 1/2 to 8 months. This suggests that the period up to 4 1/2 months constitute a sensitive period for seizures in general, and a critical period for generalized tonic-clonic seizures in this genotype. In Syn2KO mice minimal handling did not remove generalized tonic-clonic seizures, as such seizures were present when handling was introduced at 4 1/2 months. We found an initial reduction of seizure frequency, but the seizure frequency eventually reached levels seen in mice kept under regular handling regimes. Thus, it is unlikely that the period up to 4 1/2 months is a sensitive period in the Syn2KO genotype.
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Affiliation(s)
- Lars Etholm
- Section of Clinical Neurophysiology, Department of Neurology, Oslo University Hospital, Oslo, Norway.
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21
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Lalonde R, Strazielle C. Brain regions and genes affecting myoclonus in animals. Neurosci Res 2012; 74:69-79. [PMID: 22824643 DOI: 10.1016/j.neures.2012.07.004] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2012] [Revised: 06/02/2012] [Accepted: 07/12/2012] [Indexed: 01/26/2023]
Abstract
Myoclonus is defined as large-amplitude rhythmic movements. Brain regions underlying myoclonic jerks include brainstem, cerebellum, and cortex. Gamma-aminobutyric acid (GABA) appears to be the main neurotransmitter involved in myoclonus, possibly interacting with biogenic amines, opiates, acetylcholine, and glycine. Myoclonic jumping is a specific subtype seen in rodents, comprising rearing and hopping continuously against a wall. Myoclonic jumping can be seen in normal mouse strains, possibly as a result of simply being put inside a cage. Like other types, it is also triggered by changes in GABA, 5HT, and dopamine neurotransmission. Implicated brain regions include hippocampus and dorsal striatum, possibly with respect to D(1) dopamine, NMDA, and δ opioid receptors. There is reason to suspect that myoclonic jumping is underreported due to insufficient observations into mouse cages.
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Affiliation(s)
- R Lalonde
- Université de Rouen, UFR des Sciences Humaines et Sociales, Laboratoire de Psychologie et Neurosciences: Intégration COgnitive du NEurone à la Société (ICONES), 76821 Mont Saint-Aignan Cedex, France.
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22
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The prevention of behavioral consequences of idiopathic generalized epilepsy: Evidence from rodent models. Neurosci Lett 2011; 497:177-84. [DOI: 10.1016/j.neulet.2011.02.034] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2011] [Accepted: 02/15/2011] [Indexed: 12/29/2022]
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23
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Holt RL, Mikati MA. Care for child development: basic science rationale and effects of interventions. Pediatr Neurol 2011; 44:239-53. [PMID: 21397164 DOI: 10.1016/j.pediatrneurol.2010.11.009] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/30/2010] [Revised: 09/07/2010] [Accepted: 11/16/2010] [Indexed: 12/13/2022]
Abstract
The past few years have witnessed increasing interest in devising programs to enhance early childhood development. We review current understandings of brain development, recent advances in this field, and their implications for clinical interventions. An expanding body of basic science laboratory data demonstrates that several interventions, including environmental enrichment, level of parental interaction, erythropoietin, antidepressants, transcranial magnetic stimulation, transcranial direct current stimulation, hypothermia, nutritional supplements, and stem cells, can enhance cerebral plasticity. Emerging clinical data, using functional magnetic resonance imaging and clinical evaluations, also support the hypothesis that clinical interventions can increase the developmental potential of children, rather than merely allowing the child to achieve an already predetermined potential. Such interventions include early developmental enrichment programs, which have improved cognitive function; high-energy and high-protein diets, which have increased brain growth in infants with perinatal brain damage; constraint-induced movement therapy, which has improved motor function in patients with stroke, cerebral palsy, and cerebral hemispherectomy; and transcranial magnetic stimulation, which has improved motor function in stroke patients.
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Affiliation(s)
- Rebecca L Holt
- Department of Pediatric Neurology, Duke University Medical Center, Durham, NC, USA
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24
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Koe AS, Jones NC, Salzberg MR. Early life stress as an influence on limbic epilepsy: an hypothesis whose time has come? Front Behav Neurosci 2009; 3:24. [PMID: 19838325 PMCID: PMC2762371 DOI: 10.3389/neuro.08.024.2009] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2009] [Accepted: 08/18/2009] [Indexed: 01/14/2023] Open
Abstract
The pathogenesis of mesial temporal lobe epilepsy (MTLE), the most prevalent form of refractory focal epilepsy in adults, is thought to begin in early life, even though seizures may not commence until adolescence or adulthood. Amongst the range of early life factors implicated in MTLE causation (febrile seizures, traumatic brain injury, etc.), stress may be one important contributor. Early life stress is an a priori agent deserving study because of the large amount of neuroscientific data showing enduring effects on structure and function in hippocampus and amygdala, the key structures involved in MTLE. An emerging body of evidence directly tests hypotheses concerning early life stress and limbic epilepsy: early life stressors, such as maternal separation, have been shown to aggravate epileptogenesis in both status epilepticus and kindling models of limbic epilepsy. In addition to elucidating its influence on limbic epileptogenesis itself, the study of early life stress has the potential to shed light on the psychiatric disorder that accompanies MTLE. For many years, psychiatric comorbidity was viewed as an effect of epilepsy, mediated psychologically and/or neurobiologically. An alternative – or complementary – perspective is that of shared causation. Early life stress, implicated in the pathogenesis of several psychiatric disorders, may be one such causal factor. This paper aims to critically review the body of experimental evidence linking early life stress and epilepsy; to discuss the direct studies examining early life stress effects in current models of limbic seizures/epilepsy; and to suggest priorities for future research.
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Affiliation(s)
- Amelia S Koe
- Department of Medicine, Royal Melbourne Hospital, University of Melbourne Parkville, VIC, Australia
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25
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Leussis MP, Heinrichs SC. Quality of rearing guides expression of behavioral and neural seizure phenotypes in EL mice. Brain Res 2009; 1260:84-93. [PMID: 19401172 DOI: 10.1016/j.brainres.2009.01.007] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2008] [Revised: 12/25/2008] [Accepted: 01/05/2009] [Indexed: 10/21/2022]
Abstract
The present studies employed behavioral and neural markers of seizure-related plasticity to examine the relative contributions of genetic predisposition versus rearing environment in generating adult phenotypes in EL mice, a stress-induced animal model of epilepsy. Early environment was manipulated by cross-fostering pups of the EL strain to a seizure-resistant CD-1 control strain of mouse. The impact of changes in rearing quality on growth,exploratory and stress-reactivity phenotypes were examined, with a focus on the role of maternal care in shaping seizure susceptibility and neural cF os activation. Improvement in maternal care imposed by replacing biological EL dams with foster CD-1 mothers was sufficient to decrease pup mortality, to increase body weight gain (+0.1 g/day) and to delay the onset of seizure susceptibility in EL offspring beyond post-natal day 80–90. Moreover,hypoactivity in hippocampus and cortex among EL offspring cross-fostered to EL, but not CD-1 control, dams suggests that changes in rearing environment were accompanied by enduring changes in brain plasticity. Thus, neural and behavioral phenotypes of EL mice are dependent upon post-partum maternal care which if systematically enhanced can postpone seizure expression.
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Affiliation(s)
- Melanie P Leussis
- Department of Psychology, Boston College, Chestnut Hill, MA 02467, USA
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26
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Paternal care paradoxically increases offspring seizure susceptibility in the El mouse model of epilepsy. Epilepsy Behav 2008; 12:234-41. [PMID: 17964859 DOI: 10.1016/j.yebeh.2007.09.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/25/2007] [Revised: 08/28/2007] [Accepted: 09/05/2007] [Indexed: 11/23/2022]
Abstract
The El mouse is a model of idiopathic epilepsy in which seizures emerge on Postnatal Days (PNDs) 80-90, although time to first seizure can be modified by experiential factors including handling during development and history of past seizures. This study tested the hypothesis that a significant increase in the amount of parental investment would impact seizure susceptibility in adult El offspring. The study used a single dam control, in which the litter was reared by a female biological parent, and a biparental experimental group, in which both biological parents reared the litter. Components of parental care and pup body weights were quantified on PNDs 2-21, and adult offspring were examined using a handling-induced seizure susceptibility (HISS) test on PNDs 80-90 to assess the long-term impact of alterations in the perinatal environment. As expected, presence of both parents did increase parental/pup contact time by 350% relative to single-mother parenting and also reduced body weight, an index of perinatal stressor exposure, in already underweight El offspring. Accordingly, HISS testing of adult El offspring revealed a deleterious effect of biparental rearing, which increased seizure incidence to 30% relative to 0% for the single dam condition. These results suggest that the presence of a second care provider in addition to the dam constitutes a form of stressor exposure in El pups and, as a consequence, reduces the time to first seizure in genetically susceptible offspring.
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