1
|
Hajipour S, Khombi Shooshtari M, Farbood Y, Ali Mard S, Sarkaki A, Moradi Chameh H, Sistani Karampour N, Ghafouri S. Fingolimod administration following hypoxia induced neonatal seizure can restore impaired long-term potentiation and memory performance in adult rats. Neuroscience 2023; 519:107-119. [PMID: 36990271 DOI: 10.1016/j.neuroscience.2023.03.023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2022] [Revised: 02/18/2023] [Accepted: 03/21/2023] [Indexed: 03/30/2023]
Abstract
Neonatal seizures commonly caused by hypoxia can lead to long-term neurological outcomes. Early inflammation plays an important role in the pathology of these outcomes. Therefore, in the current study, we explored the long-term effects of Fingolimod (FTY720), an analog of sphingosine and potentsphingosine 1-phosphate(S1P) receptors modulator, as an anti-inflammatory and neuroprotective agent in attenuating anxiety, memory impairment, and possible alterations in gene expression of hippocampal inhibitory and excitatory receptors following hypoxia-induced neonatal seizure (HINS). Seizure was induced in 24 male and female pups (6 in each experimental group) at postnatal day 10 (P10) by premixed gas (5% oxygen/ 95% nitrogen) in a hypoxic chamber for 15 minutes. Sixty minutes after the onset of hypoxia, FTY720 (0.3 mg/kg) or saline (100 µl) was administered for 12 days (from P10 up to P21). Anxiety-like behavior and hippocampal memory function were assessed at P90 by elevated plus maze (EPM) and novel object recognition (NOR), respectively. Long-term potentiation (LTP) was recorded from hippocampal dentate gyrus region (DG) following stimulation of perforant pathway (PP). In addition, the hippocampal concentration of superoxide dismutase activity (SOD), malondialdehyde (MDA), and thiol as indices of oxidative stress were evaluated. Finally, the gene expression of NR2A subunit of N-Methyl-D-aspartic acid (NMDA) receptor, GluR2 subunit of (α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid) AMPA receptor and γ2 subunit of γ-Aminobutyric acid (GABAA) receptor were assessed at P90 by the quantitative real-time PCR. FTY720 significantly reduced later-life anxiety-like behavior, ameliorated object recognition memory and increased the amplitude and slope of the field excitatory postsynaptic potential (fEPSP) in the rats following HINS. These effects were associated with restoration of the hippocampal thiol content to the normal values and the regulatory role of FTY720 in the expression of hippocampal GABA and glutamate receptors subunits. In conclusion, FTY720 could restore the dysregulated gene expression of excitatory and inhibitory receptors. It also increased the reduced hippocampal thiol content, which was accompanied with attenuation of HINS-induced anxiety, reduced the impaired hippocampal related memory, and prevented hippocampal LTP deficits in later life following HINS.
Collapse
|
2
|
Anticonvulsant effect of pterostilbene and its influence on the anxiety- and depression-like behavior in the pentetrazol-kindled mice: behavioral, biochemical, and molecular studies. Psychopharmacology (Berl) 2021; 238:3167-3181. [PMID: 34333674 PMCID: PMC8605980 DOI: 10.1007/s00213-021-05933-5] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Accepted: 07/08/2021] [Indexed: 01/03/2023]
Abstract
RATIONALE Pterostilbene is the 3,5-dimethoxy derivative of resveratrol with numerous beneficial effects including neuroprotective properties. Experimental studies revealed its anticonvulsant action in the acute seizure tests. OBJECTIVES The purpose of the present study was to evaluate the effect of pterostilbene in the pentetrazol (PTZ)-induced kindling model of epilepsy in mice as well as to assess some possible mechanisms of its anticonvulsant action in this model. METHODS Mice were repeatedly treated with pterostilbene (50-200 mg/kg) and its effect on the development of seizure activity in the PTZ kindling was estimated. Influence of pterostilbene on the locomotor activity and anxiety- and depression-like behavior in the PTZ-kindled mice was also assessed. To understand the possible mechanisms of anticonvulsant activity of pterostilbene, γ-aminobutyric acid (GABA) and glutamate concentrations in the prefrontal cortex and hippocampus of the PTZ-kindled mice were measured using LC-MS/MS method. Moreover, mRNA expression of BDNF, TNF-α, IL-1β, IL-6, GABRA1A, and GRIN2B was determined by RT-qPCR technique. RESULTS We found that pterostilbene at a dose of 200 mg/kg considerably reduced seizure activity but did not influence the locomotor activity and depression- and anxiety-like behavior in the PTZ-kindled mice. In the prefrontal cortex and hippocampus, pterostilbene reversed the kindling-induced decrease of GABA concentration. Neither in the prefrontal cortex nor hippocampus pterostilbene affected mRNA expression of IL-1β, IL-6, GABRA1A, and GRIN2B augmented by PTZ kindling. Pterostilbene at a dose of 100 mg/kg significantly decreased BDNF and TNF-α mRNA expression in the hippocampus of the PTZ-kindled mice. CONCLUSIONS Although further studies are necessary to understand the mechanism of anticonvulsant properties of pterostilbene, our findings suggest that it might be considered a candidate for a new antiseizure drug.
Collapse
|
3
|
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.
Collapse
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
| |
Collapse
|
4
|
Rosenberg EC, Lippman-Bell JJ, Handy M, Soldan SS, Rakhade S, Hilario-Gomez C, Folweiler K, Jacobs L, Jensen FE. Regulation of seizure-induced MeCP2 Ser421 phosphorylation in the developing brain. Neurobiol Dis 2018; 116:120-130. [PMID: 29738885 DOI: 10.1016/j.nbd.2018.05.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2017] [Revised: 03/23/2018] [Accepted: 05/03/2018] [Indexed: 12/16/2022] Open
Abstract
Neonatal seizures disrupt normal synaptic maturation and often lead to later-life epilepsy and cognitive deficits. During early life, the brain exhibits heightened synaptic plasticity, in part due to a developmental overabundance of CaV1.2 L-type voltage gated calcium (Ca2+) channels (LT-VGCCs) and Ca2+-permeable AMPARs (CP-AMPARs) lacking GluA2 subunits. We hypothesized that early-life seizures overactivate these channels, in turn dysregulating Ca2+-dependent signaling pathways including that of methyl CPG binding protein 2 (MeCP2), a transcription factor implicated in the autism spectrum disorder (ASD) Rett Syndrome. Here, we show that in vivo hypoxia-induced seizures (HS) in postnatal day (P)10 rats acutely induced phosphorylation of the neuronal-specific target of activity-dependent MeCP2 phosphorylation, S421, as well as its upstream activator CaMKII T286. We next identified mechanisms by which activity-dependent Ca2+ influx induced MeCP2 phosphorylation using in vitro cortical and hippocampal neuronal cultures at embryonic day (E)18 + 10 days in vitro (DIV). In contrast to the prevalent role of NMDARs in the adult brain, we found that both CP-AMPARs and LT-VGCCs mediated MeCP2 S421 and CaMKII T286 phosphorylation induced by kainic acid (KA) or high potassium chloride (KCl) stimulation. Furthermore, in vivo post-seizure treatment with the broad-spectrum AMPAR antagonist NBQX, the CP-AMPAR blocker IEM-1460, or the LT-VGCC antagonist nimodipine blocked seizure-induced MeCP2 phosphorylation. Collectively, these results demonstrate that early-life seizures dysregulate critical activity-dependent developmental signaling pathways, in part via CP-AMPAR and LT-VGCC activation, providing novel age-specific therapeutic targets for convergent pathways underlying epilepsy and ASDs.
Collapse
Affiliation(s)
- Evan C Rosenberg
- Boston Children's Hospital, Department of Neurology, Boston, MA 02115, United States; New York University Langone Medical Center, New York, NY 10016, United States
| | - Jocelyn J Lippman-Bell
- Perelman School of Medicine, University of Pennsylvania, Department of Neurology, Philadelphia, PA 19104, United States; Boston Children's Hospital, Department of Neurology, Boston, MA 02115, United States; Philadelphia College of Osteopathic Medicine, Department of Biomedical Sciences, Philadelphia, PA 19131, United States
| | - Marcus Handy
- Perelman School of Medicine, University of Pennsylvania, Department of Neurology, Philadelphia, PA 19104, United States
| | - Samantha S Soldan
- Perelman School of Medicine, University of Pennsylvania, Department of Neurology, Philadelphia, PA 19104, United States
| | - Sanjay Rakhade
- Boston Children's Hospital, Department of Neurology, Boston, MA 02115, United States
| | | | - Kaitlyn Folweiler
- Perelman School of Medicine, University of Pennsylvania, Department of Neurology, Philadelphia, PA 19104, United States
| | - Leah Jacobs
- Perelman School of Medicine, University of Pennsylvania, Department of Neurology, Philadelphia, PA 19104, United States
| | - Frances E Jensen
- Perelman School of Medicine, University of Pennsylvania, Department of Neurology, Philadelphia, PA 19104, United States; Boston Children's Hospital, Department of Neurology, Boston, MA 02115, United States.
| |
Collapse
|
5
|
Luat AF, Behen ME, Chugani HT, Juhász C. Cognitive and motor outcomes in children with unilateral Sturge-Weber syndrome: Effect of age at seizure onset and side of brain involvement. Epilepsy Behav 2018; 80:202-207. [PMID: 29414553 PMCID: PMC5845773 DOI: 10.1016/j.yebeh.2018.01.012] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/06/2017] [Revised: 01/05/2018] [Accepted: 01/08/2018] [Indexed: 01/06/2023]
Abstract
PURPOSE Most children with Sturge-Weber syndrome (SWS) develop seizures that may contribute to neurocognitive status. In this study, we tested the hypothesis that very early seizure onset has a particularly detrimental effect on the cognitive and/or motor outcomes of children with unilateral SWS. We also tested whether side of SWS brain involvement modulates the effect of seizure variables on the pattern of cognitive abnormalities. METHODS Thirty-four children (22 girls; mean age 6.1years) with unilateral SWS and history of epilepsy in a longitudinal cohort underwent neurological and cognitive evaluations. Global intelligent quotient (GIQ), verbal intelligent quotient (VIQ), nonverbal intelligent quotient (IQ), and motor function were correlated with epilepsy variables, side and extent of brain involvement on magnetic resonance imaging (MRI). RESULTS Mean age at seizure onset was 1.3years (0.1-6years) and mean IQ at follow-up was 86 (45-118). Age at seizure onset showed a logarithmic association with IQ, with maximum impact of seizures starting before age 1year, both in uni- and multivariate regression analyses. In the left SWS group (N=20), age at seizure onset was a strong predictor of nonverbal IQ (p=0.001); while early seizure onset in the right-hemispheric group had a more global effect on cognitive functions (p=0.02). High seizure frequency and long epilepsy duration also contributed to poor outcome IQ independently in multivariate correlations. Children with motor involvement started to have seizures at/before 7months of age, while frontal lobe involvement was the strongest predictor of motor deficit in a multivariate analysis (p=0.017). CONCLUSION These findings suggest that seizure onset prior to age 1year has a profound effect on severity of cognitive and motor dysfunction in children with SWS; however, the effect of seizures on the type of cognitive deficit is influenced by laterality of brain involvement.
Collapse
Affiliation(s)
- Aimee F Luat
- Departments of Pediatrics and Neurology, Wayne State University School of Medicine, Children's Hospital of Michigan, Detroit Medical Center, 3901 Beaubien St., Detroit, MI 48201, USA.
| | - Michael E Behen
- Departments of Pediatrics and Neurology, Wayne State University School of Medicine, Children's Hospital of Michigan, Detroit Medical Center, 3901 Beaubien St., Detroit, MI 48201, USA
| | - Harry T Chugani
- Departments of Pediatrics and Neurology, Wayne State University School of Medicine, Children's Hospital of Michigan, Detroit Medical Center, 3901 Beaubien St., Detroit, MI 48201, USA; Department of Neurology, School of Medicine, Thomas Jefferson University, Philadelphia, PA, USA; Division of Pediatric Neurology, Nemours A.I. DuPont Hospital for Children, 1600 Rockland Rd., Wilmington, Delaware, 19803, USA
| | - Csaba Juhász
- Departments of Pediatrics and Neurology, Wayne State University School of Medicine, Children's Hospital of Michigan, Detroit Medical Center, 3901 Beaubien St., Detroit, MI 48201, USA
| |
Collapse
|
6
|
The Functional and Molecular Properties, Physiological Functions, and Pathophysiological Roles of GluN2A in the Central Nervous System. Mol Neurobiol 2016; 54:1008-1021. [DOI: 10.1007/s12035-016-9715-7] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2015] [Accepted: 01/11/2016] [Indexed: 11/25/2022]
|
7
|
Torolira D, Suchomelova L, Wasterlain CG, Niquet J. Widespread neuronal injury in a model of cholinergic status epilepticus in postnatal day 7 rat pups. Epilepsy Res 2015; 120:47-54. [PMID: 26709882 DOI: 10.1016/j.eplepsyres.2015.11.005] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2015] [Revised: 10/27/2015] [Accepted: 11/09/2015] [Indexed: 11/16/2022]
Abstract
OBJECTIVE Status Epilepticus (SE) is common in neonates and infants, and is associated with neuronal injury and adverse developmental outcomes. However, the role of SE in this injury is uncertain. Until now, we have lacked an animal model in which seizures result in neuronal injury in rodent models at ages below postnatal day 12 (P12) unless seizures are combined with inflammatory stressors. METHODS We induced SE with high-dose lithium and pilocarpine in P7 rats, which are developmentally close to human neonates. Several EEG measures and O2 saturation were recorded during the 6h following initiation of SE. We assessed neuronal injury at 6 and 24h post-SE onset using Fluoro-Jade B staining (FJB) and caspase-3a immunoreactivity (IR). RESULTS EEGs showed continuous polyspikes activity for 54.3 ± 6.7 min, while O2 saturation showed no significant hypoxemia. By 24h after SE onset, significant neuronal injury was observed in CA1/subiculum, CA3, dentate gyrus, thalamus, neocortex, amygdala, piriform cortex, lateral entorhinal cortex, hypothalamus, caudate putamen, globus pallidus, ventral pallidum, and nucleus accumbens. At 24h post-SE, caspase-3a IR was significantly increased in CA1/subiculum, thalamus, and neocortex compared to sham, and caspase-3a IR neurons had fragmented nuclei, suggesting that SE triggered an irreversible form of cell injury. SIGNIFICANCE In conclusion, we have developed a model of cholinergic SE in P7 rat pups, which combines high survival (69.9% survival at 24h) and widespread brain injury. These studies suggest that the immature brain is vulnerable to severe forms of SE.
Collapse
Affiliation(s)
- Daniel Torolira
- Epilepsy Research Laboratory (151), Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, CA, USA
| | - Lucie Suchomelova
- Epilepsy Research Laboratory (151), Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, CA, USA
| | - Claude G Wasterlain
- Epilepsy Research Laboratory (151), Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, CA, USA; Department of Neurology, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA; Brain Research Institute, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
| | - Jerome Niquet
- Epilepsy Research Laboratory (151), Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, CA, USA; Department of Neurology, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA.
| |
Collapse
|
8
|
Bernard PB, Benke TA. Early life seizures: evidence for chronic deficits linked to autism and intellectual disability across species and models. Exp Neurol 2014; 263:72-8. [PMID: 25284323 DOI: 10.1016/j.expneurol.2014.09.018] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2014] [Revised: 09/02/2014] [Accepted: 09/16/2014] [Indexed: 11/08/2022]
Abstract
Recent work in Exp Neurol by Lugo et al. (2014b) demonstrated chronic alterations in sociability, learning and memory following multiple early life seizures (ELS) in a mouse model. This work adds to the growing body of evidence supporting the detrimental nature of ELS on the developing brain to contribute to aspects of an autistic phenotype with intellectual disability. Review of the face validity of behavioral testing and the construct validity of the models used informs the predictive ability and thus the utility of these models to translate underlying molecular and cellular mechanisms into future human studies.
Collapse
Affiliation(s)
- Paul B Bernard
- Department of Pediatrics, University of Colorado, School of Medicine, USA
| | - Tim A Benke
- Department of Pediatrics, University of Colorado, School of Medicine, USA; Neuroscience Graduate Program, University of Colorado, School of Medicine, USA; Department of Neurology, University of Colorado, School of Medicine, USA; Department of Pharmacology, University of Colorado, School of Medicine, USA; Department of Otolaryngology, University of Colorado, School of Medicine, USA.
| |
Collapse
|
9
|
Ohmori I, Kawakami N, Liu S, Wang H, Miyazaki I, Asanuma M, Michiue H, Matsui H, Mashimo T, Ouchida M. Methylphenidate improves learning impairments and hyperthermia-induced seizures caused by an Scn1a mutation. Epilepsia 2014; 55:1558-67. [PMID: 25154505 DOI: 10.1111/epi.12750] [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] [Accepted: 07/16/2014] [Indexed: 11/25/2022]
Abstract
OBJECTIVE Developmental disorders including cognitive deficit, hyperkinetic disorder, and autistic behaviors are frequently comorbid in epileptic patients with SCN1A mutations. However, the mechanisms underlying these developmental disorders are poorly understood and treatments are currently unavailable. Using a rodent model with an Scn1a mutation, we aimed to elucidate the pathophysiologic basis and potential therapeutic treatments for developmental disorders stemming from Scn1a mutations. METHODS We conducted behavioral analyses on rats with the N1417H-Scn1a mutation. With high-performance liquid chromatography, we measured dopamine and its metabolites in the frontal cortex, striatum, nucleus accumbens, and midbrain. Methylphenidate was administered intraperitoneally to examine its effects on developmental disorder-like behaviors and hyperthermia-induced seizures. RESULTS Behavioral studies revealed that Scn1a-mutant rats had repetitive behavior, hyperactivity, anxiety-like behavior, spatial learning impairments, and motor imbalance. Dopamine levels in the striatum and nucleus accumbens in Scn1a-mutant rats were significantly lower than those in wild-type rats. In Scn1a-mutant rats, methylphenidate, by increasing dopamine levels in the synaptic cleft, improved hyperactivity, anxiety-like behavior, and spatial learning impairments. Surprisingly, methylphenidate also strongly suppressed hyperthermia-induced seizures. SIGNIFICANCE Dysfunction of the mesolimbic dopamine reward pathway may contribute to the hyperactivity and learning impairments in Scn1a-mutant rats. Methylphenidate was effective for treating hyperactivity, learning impairments, and hyperthermia-induced seizures. We propose that methylphenidate treatment may ameliorate not only developmental disorders but also epileptic seizures in patients with SCN1A mutations.
Collapse
Affiliation(s)
- Iori Ohmori
- Department of Physiology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan; Department of Medical Ethics, Graduate School and Faculty of Medicine, Kyoto University, Kyoto, Japan
| | | | | | | | | | | | | | | | | | | |
Collapse
|
10
|
Influences of hyperthermia-induced seizures on learning, memory and phosphorylative state of CaMKIIα in rat hippocampus. Brain Res 2014; 1557:190-200. [PMID: 24560900 DOI: 10.1016/j.brainres.2014.02.026] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2013] [Revised: 01/15/2014] [Accepted: 02/12/2014] [Indexed: 11/22/2022]
Abstract
Febrile seizure (FS) remains the most common childhood neurological emergency. Although many studies have been done, controversy exists as to whether these seizures are associated with a significant risk for cognitive impairment. The aim of our study is to check whether there is a spatial learning and memory deficit in the experimental FS rats using a heated-air FS paradigm and to determine the possible molecular mechanism of cognitive impairment. On days 10 to 12 postpartum, the male rat pups were subjected to one, three, or nine episodes of brief hyperthermia-induced seizures (HS). At adolescence and adulthood, the rats subjected to three, or nine episodes of HS had significant deficits in spatial learning and memory tested by Morris water maze. At adulthood, no apparent hippocampal neuronal loss was found in any HS group, but the seizure threshold to flurothyl was decreased significantly in the rats subjected to nine episodes of HS. In the rats subjected to three, or nine episodes of HS, the Western immunoblotting showed that there was a significant translocation of Ca(2+)-calmodulin stimulated protein kinase II (CaMKII) from the postsynaptic density to the cytosol. In the postsynaptic density the phosphorylation of CaMKIIα Thr(286) was reduced significantly, but the phosphorylation of CaMKIIα Thr(305) was increased significantly. Our study showed early-life brief but recurrent HS caused long-term cognitive impairment and CaMKIIα was involved in carrying forward the signal resulting from HS. The change of the phosphorylative level in Thr(286) and Thr(305) sites of CaMKIIα may underlie the molecular mechanism for the HS related cognitive impairment.
Collapse
|
11
|
Kandratavicius L, Ruggiero RN, Hallak JE, Garcia-Cairasco N, Leite JP. Pathophysiology of mood disorders in temporal lobe epilepsy. BRAZILIAN JOURNAL OF PSYCHIATRY 2013; 34 Suppl 2:S233-45. [PMID: 23429849 DOI: 10.1016/j.rbp.2012.08.003] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
OBJECTIVE There is accumulating evidence that the limbic system is pathologically involved in cases of psychiatric comorbidities in temporal lobe epilepsy (TLE) patients. Our objective was to develop a conceptual framework describing how neuropathological, neurochemical and electrophysiological aspects might contribute to the development of psychiatric symptoms in TLE and the putative neurobiological mechanisms that cause mood disorders in this patient subgroup. METHODS In this review, clinical, experimental and neuropathological findings, as well as neurochemical features of the limbic system were examined together to enhance our understanding of the association between TLE and psychiatric comorbidities. Finally, the value of animal models in epilepsy and mood disorders was discussed. CONCLUSIONS TLE and psychiatric symptoms coexist more frequently than chance would predict. Alterations and neurotransmission disturbance among critical anatomical networks, and impaired or aberrant plastic changes might predispose patients with TLE to mood disorders. Clinical and experimental studies of the effects of seizures on behavior and electrophysiological patterns may offer a model of how limbic seizures increase the vulnerability of TLE patients to precipitants of psychiatric symptoms.
Collapse
Affiliation(s)
- Ludmyla Kandratavicius
- Department of Neurosciences and Behavior, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Brazil.
| | | | | | | | | |
Collapse
|
12
|
Swijsen A, Avila A, Brône B, Janssen D, Hoogland G, Rigo JM. Experimental early-life febrile seizures induce changes in GABA(A) R-mediated neurotransmission in the dentate gyrus. Epilepsia 2012; 53:1968-77. [PMID: 23030508 DOI: 10.1111/j.1528-1167.2012.03694.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
PURPOSE Febrile seizures (FS), the most frequent seizure type during childhood, have been linked to temporal lobe epilepsy (TLE) in adulthood. Yet, underlying mechanisms are still largely unknown. Altered γ-aminobutyric acid (GABA)ergic neurotransmission in the dentate gyrus (DG) circuit has been hypothesized to be involved. This study aims at analyzing whether experimental FS change inhibitory synaptic input and postsynaptic GABA(A) R function in dentate granule cells. METHODS We applied an immature rat model of hyperthermia (HT)-induced FS. GABA(A) R-mediated neurotransmission was studied using whole-cell patch-clamp recordings from dentate granule neurons in hippocampal slices within 6-9 days post-HT. KEY FINDINGS Frequencies of spontaneous inhibitory postsynaptic currents (sIPSCs) were reduced in HT rats that had experienced seizures, whereas sIPSC amplitudes were enhanced. Whole-cell GABA responses revealed a doubled GABA(A) R sensitivity in dentate granule cells from HT animals, compared to that of normothermic (NT) controls. Analysis of sIPSCs and whole-cell GABA responses showed similar kinetics in postsynaptic GABA(A) Rs of HT and NT rats. quantitative real-time polymerase chain reaction (qPCR) experiments indicated changes in DG GABA(A) R subunit expression, which was most pronounced for the α3 subunit. SIGNIFICANCE The data support the hypothesis that FS persistently alter neuronal excitability.
Collapse
Affiliation(s)
- Ann Swijsen
- BIOMED Research Institute, Hasselt University/Transnational University Limburg, Diepenbeek, Belgium
| | | | | | | | | | | |
Collapse
|
13
|
Butler T, Weisholtz D, Isenberg N, Harding E, Epstein J, Stern E, Silbersweig D. Neuroimaging of frontal-limbic dysfunction in schizophrenia and epilepsy-related psychosis: toward a convergent neurobiology. Epilepsy Behav 2012; 23:113-22. [PMID: 22209327 PMCID: PMC3339259 DOI: 10.1016/j.yebeh.2011.11.004] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/10/2011] [Revised: 09/28/2011] [Accepted: 11/06/2011] [Indexed: 12/27/2022]
Abstract
Psychosis is a devastating, prevalent condition considered to involve dysfunction of frontal and medial temporal limbic brain regions as key nodes in distributed brain networks involved in emotional regulation. The psychoses of epilepsy represent an important, though understudied, model relevant to understanding the pathophysiology of psychosis in general. In this review, we (1) discuss the classification of epilepsy-related psychoses and relevant neuroimaging and other studies; (2) review structural and functional neuroimaging studies of schizophrenia focusing on evidence of frontal-limbic dysfunction; (3) report our laboratory's PET, fMRI, and electrophysiological findings; (4) describe a theoretical framework in which frontal hypoactivity and intermittent medial temporal hyperactivity play a critical role in the etiopathology of psychosis both associated and unassociated with epilepsy; and (5) suggest avenues for future research.
Collapse
Affiliation(s)
- Tracy Butler
- NYU Comprehensive Epilepsy Center, Department of Neurology, New York University School of Medicine, New York, NY, USA.
| | - Daniel Weisholtz
- Functional Neuroimaging Laboratory, Department of Psychiatry, Brigham and Women's Hospital, Harvard Medical School, Boston, MA
| | - Nancy Isenberg
- Division of Behavioral Neurology, New Jersey Neuroscience Institute, Edison, NJ
| | - Elizabeth Harding
- Functional Neuroimaging Laboratory, Department of Psychiatry, Brigham and Women's Hospital, Harvard Medical School, Boston, MA
| | - Jane Epstein
- Functional Neuroimaging Laboratory, Department of Psychiatry, Brigham and Women's Hospital, Harvard Medical School, Boston, MA
| | - Emily Stern
- Functional Neuroimaging Laboratory, Department of Psychiatry, Brigham and Women's Hospital, Harvard Medical School, Boston, MA
| | - David Silbersweig
- Functional Neuroimaging Laboratory, Department of Psychiatry, Brigham and Women's Hospital, Harvard Medical School, Boston, MA
| |
Collapse
|
14
|
Holmes GL, Milh MM, Dulac O. Maturation of the human brain and epilepsy. HANDBOOK OF CLINICAL NEUROLOGY 2012; 107:135-43. [DOI: 10.1016/b978-0-444-52898-8.00007-0] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
|
15
|
Cognato GP, Vuaden FC, Savio LEB, Bellaver B, Casali E, Bogo MR, Souza DOG, Sévigny J, Bonan CD. Nucleoside triphosphate diphosphohydrolases role in the pathophysiology of cognitive impairment induced by seizure in early age. Neuroscience 2011; 180:191-200. [PMID: 21315806 DOI: 10.1016/j.neuroscience.2011.01.065] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2010] [Revised: 01/31/2011] [Accepted: 01/31/2011] [Indexed: 11/15/2022]
Abstract
Studies have shown that seizures in young animals lead to later cognitive deficits. There is evidence that long-term potentiation (LTP) and long-term depression (LTD) might contribute to the neural basis for learning and memory mechanism and might be modulated by ATP and/or its dephosphorylated product adenosine produced by a cascade of cell-surface transmembrane enzymes, such as E-NTPDases (ecto-nucleoside triphosphate diphosphohydrolases) and ecto-5'-nucleotidase. Thus, we have investigated if hippocampal ecto-nucleotidase activities are altered at different time periods after one episode of seizure induced by kainic acid (KA) in 7 days old rats. We also have evaluated if 90 day-old rats previously submitted to seizure induced by KA at 7 days of age presented cognitive impairment in Y-maze behavior task. Our results have shown memory impairment of adult rats (Postnatal day 90) previously submitted to one single seizure episode in neonatal period (Postnatal day 7), which is accompanied by an increased ATP hydrolysis in hippocampal synaptosomes. The metabolism of ATP evaluated by HPLC confirmed that ATP hydrolysis was faster in adult rats treated with KA in neonatal period than in controls. Surprisingly, the mRNA and protein levels as seen by PCR and Western blot, respectively, were not altered by the KA administration in early age. Since we have found an augmented hydrolysis of ATP and this nucleotide seems to be important to LTP induction, we could assume that impairment of memory and learning observed in adult rats which have experienced a convulsive episode in postnatal period may be a consequence of the increased ATP hydrolysis. These findings correlate the purinergic signaling to the cognitive deficits induced by neonatal seizures and contribute to a better understanding about the mechanisms of seizure-induced memory dysfunction.
Collapse
Affiliation(s)
- G P Cognato
- Departamento de Bioquímica, Universidade Federal do Rio Grande do Sul, Avenida Ramiro Barcelos, 2600 Anexo, 90035-000 Porto Alegre, Rio Grande do Sul, Brazil
| | | | | | | | | | | | | | | | | |
Collapse
|
16
|
Saghyan A, LaTorre GN, Keesey R, Sharma A, Mehta V, Rudenko V, Hallas BH, Rafiuddin A, Goldstein B, Friedman LK. Glutamatergic and morphological alterations associated with early life seizure-induced preconditioning in young rats. Eur J Neurosci 2010; 32:1897-911. [DOI: 10.1111/j.1460-9568.2010.07464.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
|
17
|
Laurén HB, Lopez-Picon FR, Brandt AM, Rios-Rojas CJ, Holopainen IE. Transcriptome analysis of the hippocampal CA1 pyramidal cell region after kainic acid-induced status epilepticus in juvenile rats. PLoS One 2010; 5:e10733. [PMID: 20505763 PMCID: PMC2873964 DOI: 10.1371/journal.pone.0010733] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2009] [Accepted: 04/28/2010] [Indexed: 11/19/2022] Open
Abstract
Molecular mechanisms involved in epileptogenesis in the developing brain remain poorly understood. The gene array approach could reveal some of the factors involved by allowing the identification of a broad scale of genes altered by seizures. In this study we used microarray analysis to reveal the gene expression profile of the laser microdissected hippocampal CA1 subregion one week after kainic acid (KA)-induced status epilepticus (SE) in 21-day-old rats, which are developmentally roughly comparable to juvenile children. The gene expression analysis with the Chipster software generated a total of 1592 differently expressed genes in the CA1 subregion of KA-treated rats compared to control rats. The KEGG database revealed that the identified genes were involved in pathways such as oxidative phosporylation (26 genes changed), and long-term potentiation (LTP; 18 genes changed). Also genes involved in Ca2+ homeostasis, gliosis, inflammation, and GABAergic transmission were altered. To validate the microarray results we further examined the protein expression for a subset of selected genes, glial fibrillary protein (GFAP), apolipoprotein E (apo E), cannabinoid type 1 receptor (CB1), Purkinje cell protein 4 (PEP-19), and interleukin 8 receptor (CXCR1), with immunohistochemistry, which confirmed the transcriptome results. Our results showed that SE resulted in no obvious CA1 neuronal loss, and alterations in the expression pattern of several genes during the early epileptogenic phase were comparable to previous gene expression studies of the adult hippocampus of both experimental epileptic animals and patients with temporal lobe epilepsy (TLE). However, some changes seem to occur after SE specifically in the juvenile rat hippocampus. Insight of the SE-induced alterations in gene expression and their related pathways could give us hints for the development of new target-specific antiepileptic drugs that interfere with the progression of the disease in the juvenile age group.
Collapse
Affiliation(s)
- Hanna B. Laurén
- Department of Pharmacology, Drug Development, and Therapeutics, Institute of Biomedicine, University of Turku, Turku, Finland
- MediCity Research Laboratory, Turku, Finland
| | - Francisco R. Lopez-Picon
- Department of Pharmacology, Drug Development, and Therapeutics, Institute of Biomedicine, University of Turku, Turku, Finland
| | - Annika M. Brandt
- Turku Centre for Biotechnology, University of Turku and Åbo Akademi University, Turku, Finland
| | - Clarissa J. Rios-Rojas
- Turku Centre for Biotechnology, University of Turku and Åbo Akademi University, Turku, Finland
| | - Irma E. Holopainen
- Department of Pharmacology, Drug Development, and Therapeutics, Institute of Biomedicine, University of Turku, Turku, Finland
- MediCity Research Laboratory, Turku, Finland
- * E-mail:
| |
Collapse
|
18
|
Isaeva E, Isaev D, Savrasova A, Khazipov R, Holmes GL. Recurrent neonatal seizures result in long-term increases in neuronal network excitability in the rat neocortex. Eur J Neurosci 2010; 31:1446-55. [PMID: 20384780 DOI: 10.1111/j.1460-9568.2010.07179.x] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Neonatal seizures are associated with a high likelihood of adverse neurological outcomes, including mental retardation, behavioral disorders, and epilepsy. Early seizures typically involve the neocortex, and post-neonatal epilepsy is often of neocortical origin. However, our understanding of the consequences of neonatal seizures for neocortical function is limited. In the present study, we show that neonatal seizures induced by flurothyl result in markedly enhanced susceptibility of the neocortex to seizure-like activity. This change occurs in young rats studied weeks after the last induced seizure and in adult rats studied months after the initial seizures. Neonatal seizures resulted in reductions in the amplitude of spontaneous inhibitory postsynaptic currents and the frequency of miniature inhibitory postsynaptic currents, and significant increases in the amplitude and frequency of spontaneous excitatory postsynaptic currents (sEPSCs) and in the frequency of miniature excitatory postsynaptic currents (mEPSCs) in pyramidal cells of layer 2/3 of the somatosensory cortex. The selective N-methyl-D-aspartate (NMDA) receptor antagonist D-2-amino-5-phosphonovalerate eliminated the differences in amplitude and frequency of sEPSCs and mEPSCs in the control and flurothyl groups, suggesting that NMDA receptors contribute significantly to the enhanced excitability seen in slices from rats that experienced recurrent neonatal seizures. Taken together, our results suggest that recurrent seizures in infancy result in a persistent enhancement of neocortical excitability.
Collapse
Affiliation(s)
- Elena Isaeva
- Department of Neurology, Neuroscience Center at Dartmouth, Dartmouth Medical School, Lebanon, NH 03756, USA.
| | | | | | | | | |
Collapse
|
19
|
Time-dependent changes in learning ability and induction of long-term potentiation in the lithium-pilocarpine-induced epileptic mouse model. Epilepsy Behav 2010; 17:448-54. [PMID: 20332069 DOI: 10.1016/j.yebeh.2010.02.008] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/22/2009] [Revised: 02/12/2010] [Accepted: 02/13/2010] [Indexed: 11/23/2022]
Abstract
To explore the mechanism underlying the development of learning deficits in patients with epilepsy, we generated a mouse model for temporal lobe epilepsy by intraperitoneally injecting mice with pilocarpine with lithium chloride, and investigated time-dependent changes in both contextual fear memory of those model mice and long-term potentiation (LTP) in hippocampal CA1 neurons 1 day, 2 weeks, and 6 weeks after the onset of status epilepticus (SE). Fear memory formation did not change 1 day and 2 weeks after the onset of SE, but was significantly reduced after 6 weeks. Induction of LTP was enhanced 1 day after the onset of SE, but returned to the normal level 2 weeks later, and was almost completely attenuated after 6 weeks. The enhancement of LTP was accompanied by an increase in output responses of excitatory postsynaptic potentials, whereas suppression of LTP was accompanied by alteration of the ratio of paired pulse facilitation. These results indicate that time-dependent changes of LTP induction have a causal role in the development of learning deficits of epilepsy patients.
Collapse
|
20
|
Abstract
The highest incidence of seizures occurs during the first hours to days after birth. The immature brain is prone to seizures because of reduced inhibition. GABA, which is the primary inhibitory neurotransmitter in the mature brain, is depolarizing and excitatory in the immature brain. Seizures are an ominous sign, indicating either an acquired brain insult or a genetic abnormality. While the primary outcome determinant of neonatal seizures is etiology, whether seizures can result in long-term adverse consequences independently is not clear. While the clinical data is uncertain, there is now a considerable body of evidence indicating that in animals, neonatal seizures can adversely alter the developing brain. Animal data indicates that the sequelae of seizures are strongly age dependent; seizures will affect the developing and plastic neuronal circuitry much differently than the fixed circuitry of the mature brain. Seizures at an early developmental stage can dramatically affect the construction of networks, resulting in severe and permanent handicaps in some patients. In the young brain, the long-lasting detrimental consequences of seizures are caused by an alteration of developmental programs rather than by neuronal cell loss, as occurs in adults. In animal models, neonatal seizures result in decreases in neurogenesis, sprouting of mossy fibers, and long-standing changes in signaling properties. Seizures in rat pups are also associated with abnormalities in firing patterns of single cells in the hippocampus. Furthermore, these anatomic and physiologic changes correlate well with behavioral dysfunction.
Collapse
Affiliation(s)
- Gregory L Holmes
- Department of Neurology, Dartmouth-Hitchcock Medical Center, Neuroscience Center at Dartmouth, Dartmouth Medical School, One Medical Center Drive, Lebanon, NH 03756, USA.
| |
Collapse
|
21
|
Potential role for ligand-gated ion channels after seizure-induced neurogenesis. Biochem Soc Trans 2009; 37:1419-22. [DOI: 10.1042/bst0371419] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Epileptic seizures result in an increased generation of new neurons in the dentate gyrus of the adult mammalian hippocampus. The role of these seizure-induced newborn neurons in the process of epileptogenesis remains largely unknown. Recent work, however, suggests an aberrant incorporation of newborn cells into the existing hippocampal network in such a way that they promote hippocampal hyperexcitability. In the present review, we discuss current knowledge about the possible role of seizure-induced newly generated neurons and the putative involvement of ligand-gated ion channels in the process of epileptogenesis.
Collapse
|
22
|
Lin H, Holmes GL, Kubie JL, Muller RU. Recurrent seizures induce a reversible impairment in a spatial hidden goal task. Hippocampus 2009; 19:817-27. [PMID: 19235227 DOI: 10.1002/hipo.20565] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
A major question concerning the learning and memory deficits characteristic of epilepsy is the relative importance of the initial insult that leads to recurrent, unprovoked seizures versus the seizures themselves. A related issue is whether seizure-induced cognitive decline is permanent or reversible when convulsions cease. To address these problems, adult rats were extensively trained in the "spatial accuracy task," a dry-land analog of the Morris water maze. This task allows the rat's estimate of the location of a hidden goal zone to be repeatedly measured within each behavioral session. One aim was to measure, in well-trained animals, the time course of any cognitive impairment caused by a daily flurothyl-induced generalized seizure over 11 days. A second aim was to look for possible recovery during 9 subsequent days with no seizures. We saw a cumulative degradation in spatial performance during the seizure days and reversal of the deficit after seizures were stopped such that performance returned to baseline. Interestingly, the rate of learning to an asymptote, the rate of performance decline during one-per-day seizures and the rate of relearning during the recovery period were all similar. Given that the hippocampus plays an important role in spatial memory and that it is the brain structure most vulnerable to abnormal excitation the implication is that the hippocampus remains essential for precise spatial navigation even after prolonged training in locating a fixed goal zone. Clinically, this finding questions the assumption that patients who experience seizures should return to a baseline cognitive level within hours.
Collapse
Affiliation(s)
- Hai Lin
- Program in Neural and Behavioral Science, SUNY Downstate Medical Center, Brooklyn, New York 11203, USA
| | | | | | | |
Collapse
|
23
|
Holmes GL. The 2008 Judith Hoyer lecture: epilepsy in children: listening to mothers. Epilepsy Behav 2009; 16:193-202. [PMID: 19720568 PMCID: PMC2760824 DOI: 10.1016/j.yebeh.2009.07.029] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/16/2009] [Accepted: 07/17/2009] [Indexed: 12/29/2022]
Abstract
The incidence of epilepsy is significantly higher in children than adults. When faced with the diagnosis of epilepsy, parents have many questions regarding cause, treatment, and prognosis. Although the majority of children with epilepsy have an excellent prognosis and respond well to therapy, some children are refractory to therapy and suffer from cognitive decline. Animal models are now providing insights into the mechanisms responsible for the high incidence of seizures during development and age-dependent seizure-induced damage. One of the causes of the increased susceptibility of the young brain to seizures is the depolarizing effects of GABA secondary to high intracellular concentrations of chloride in young neurons. Although cell loss is not a feature of seizures in the young brain, recurrent seizures do result in aberrant sprouting of mossy fibers, reduce neurogenesis, and alter excitatory and inhibitory neurotransmitter receptor structure and function. Behavioral consequences of early-life seizures include impaired spatial cognition, which now can be assessed using single-cell recordings from the hippocampus. Antiepileptic drugs have had a tremendous positive influence in epilepsy management, although there are now a number of studies demonstrating that antiepileptic drugs at therapeutic concentrations can impair cognition and result in increased apoptosis. While clinical judgment and experience are paramount when discussing the consequences of seizures and their treatment, awareness of studies from animals can provide the clinician with guidance in addressing these important issues with parents.
Collapse
Affiliation(s)
- Gregory L Holmes
- Department of Neurology, Center for Neuroscience at Dartmouth, Dartmouth Medical School, Hanover, NH, USA.
| |
Collapse
|
24
|
Effects of postnatal exposure to methylmercury on spatial learning and memory and brain NMDA receptor mRNA expression in rats. Toxicol Lett 2009; 188:230-5. [PMID: 19409459 DOI: 10.1016/j.toxlet.2009.04.021] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2008] [Revised: 04/08/2009] [Accepted: 04/20/2009] [Indexed: 12/21/2022]
Abstract
The extreme vulnerability of developing nervous system to methylmercury (MeHg) is well documented. Still unclear is the consequence of different postnatal period exposure to MeHg. We investigated the critical postnatal phase when MeHg induced neurotoxicity in rats and the underlying mechanism. Rats were given 5mg/(kg day) methylmercury chloride (MMC) orally on postnatal day (PND) 7, PND14, PND28, and PND60 for consecutive 7 days. A control group was treated with 0.9% sodium chloride solution 5 ml/(kg day) instead. On PND69, spatial learning and memory was evaluated by Morris water maze test. Behavior deficits were found in MMC-treated rats of PND7 and PND14 groups (p<0.01). N-methyl-D-aspartate (NMDA) receptor 2 subunits mRNA expressions were evaluated 3 days after the last administration. In hippocampus, the mRNA expression of NR2A and NR2B decreased, but the NR2C expression increased in PND14 group following MMC-treatment (p<0.01). In cerebral cortex, mRNA expression of NR2A decreased, with NR2C expression elevating in PND14 group following MMC-treatment (p<0.05). These observations suggest that the postnatal exposure to MeHg during PND7-20 could cause neurobehavioral deficits which extend to adulthood. Furthermore, the abnormal expression of NMDAR 2 subunits might associate with the impairment.
Collapse
|
25
|
Thibeault-Eybalin MP, Lortie A, Carmant L. Neonatal seizures: do they damage the brain? Pediatr Neurol 2009; 40:175-80. [PMID: 19218030 DOI: 10.1016/j.pediatrneurol.2008.10.026] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/14/2008] [Revised: 10/01/2008] [Accepted: 10/01/2008] [Indexed: 01/10/2023]
Abstract
Seizures are an early sign of brain injury in newborns. These seizures are in most cases repetitive or associated with asymptomatic electrographic seizures. Despite the relative resistance of the immature brain to seizure-induced brain damage, there is more and more evidence that neonatal seizures impair normal brain development. This review addresses the changes associated with neonatal seizures and discusses current and future potential neuroprotective strategies.
Collapse
|
26
|
Lin TC, Huang LT, Huang YN, Chen GS, Wang JY. Neonatal status epilepticus alters prefrontal-striatal circuitry and enhances methamphetamine-induced behavioral sensitization in adolescence. Epilepsy Behav 2009; 14:316-23. [PMID: 19126440 DOI: 10.1016/j.yebeh.2008.12.005] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/23/2008] [Revised: 11/30/2008] [Accepted: 12/13/2008] [Indexed: 11/24/2022]
Abstract
Neonatal seizures may alter the developing neurocircuitry and cause behavioral abnormalities in adulthood. We found that rats previously subjected to lithium-pilocarpine (LiPC)-induced neonatal status epilepticus (NeoSE) exhibited enhanced behavioral sensitization to methamphetamine (MA) in adolescence. Neurochemically, dopamine (DA) and metabolites were markedly decreased in prefrontal cortex (PFC) and insignificantly changed in striatum by NeoSE, but were increased in both PFC and striatum by NeoSE+MA. Glutamate levels were increased in both PFC and striatum in the NeoSE+MA group. DA turnover, an index of utilization and activity, was increased by NeoSE but reversed by MA in PFC. Gene expression of the regulator of G-protein signaling 4 (RGS4) was downregulated in PFC and striatum by NeoSE and further suppressed by MA. These findings suggest NeoSE affects both dopaminergic and glutamatergic systems in the prefrontal-striatal circuitry that manifests as enhanced behavioral sensitization to MA in adolescence.
Collapse
Affiliation(s)
- Tzu-Chao Lin
- Graduate Institute of Medical Sciences, National Defense Medical Center, Taipei, Taiwan, ROC
| | | | | | | | | |
Collapse
|
27
|
Ni H, Jiang YW, Tao LY, Jin MF, Wu XR. ZnT-1, ZnT-3, CaMK II, PRG-1 expressions in hippocampus following neonatal seizure-induced cognitive deficit in rats. Toxicol Lett 2009; 184:145-50. [DOI: 10.1016/j.toxlet.2008.11.003] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2008] [Revised: 11/03/2008] [Accepted: 11/07/2008] [Indexed: 10/21/2022]
|
28
|
Abstract
The autisms and epilepsies are heterogeneous disorders that have diverse etiologies and pathologies. The severity of impairment and of symptoms associated with autism or with particular epilepsy syndromes reflects focal or global, structurally abnormal or dysfunctional neuronal networks. The complex relationship between autism and epilepsy, as reflected in the autism-epilepsy phenotype, provides a bridge to further knowledge of shared neuronal networks that can account for both the autisms and the epilepsies. Although epilepsy is not a causal factor for autism, increased understanding of common genetic and molecular biological mechanisms of the autism-epilepsy phenotype has provided insight into the pathophysiology of the autisms. The autism-epilepsy phenotype provides a novel model to the study of interventions that may have a positive modulating effects on social cognitive outcome.
Collapse
Affiliation(s)
- Roberto Tuchman
- Department of Neurology, University of Miami, Miami Children's Hospital, Dan Marino Center, 2900 South Commerce Parkway, Weston, FL, USA.
| | | | | |
Collapse
|
29
|
Holmes GL, Zhao Q. Choosing the correct antiepileptic drugs: from animal studies to the clinic. Pediatr Neurol 2008; 38:151-62. [PMID: 18279749 PMCID: PMC2720574 DOI: 10.1016/j.pediatrneurol.2007.09.008] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/05/2007] [Revised: 07/27/2007] [Accepted: 09/17/2007] [Indexed: 01/13/2023]
Abstract
Epilepsy is a chronic condition caused by an imbalance of normal excitatory and inhibitory forces in the brain. Antiepileptic drug therapy is directed primarily toward reducing excitability through blockage of voltage-gated Na(+) or Ca(2+) channels, or increasing inhibition through enhancement of gamma-aminobutyric acid currents. Prior to clinical studies, putative antiepileptic drugs are screened in animals (usually rodents). Maximal electrical shock, pentylenetetrazol, and kindling are typically used as nonmechanistic screens for antiseizure properties, and the rotorod test assesses acute toxicity. Whereas antiseizure drug screening has been successful in bringing drugs to the market and improving our understanding of the pathophysiology of seizures, it merits emphasis that the vast majority of drug screening occurs in mature male rodents and involves models of seizures, not epilepsy. Effective drugs in acute seizures may not be effective in chronic models of epilepsy. Seizure type, clinical and electroencephalographic phenotype, syndrome, and etiology are often quite different in children with epilepsy than in adults. Despite these age-related unique features, drugs used in children are generally the same as those in adults. As awareness of the unique features of seizures during development increases, more drug screening in the immature animal will likely occur.
Collapse
Affiliation(s)
- Gregory L Holmes
- Section of Neurology, Neuroscience Center at Dartmouth, Dartmouth Medical School, Dartmouth-Hitchcock Medical Center, One Medical Center Drive, Lebanon, NH 03756, USA.
| | | |
Collapse
|
30
|
Abstract
The mechanisms of memory delineated by the model of long-term potentiation (LTP) are similar to those underlying epileptogenesis by kindling. Memory is impaired by seizures and epilepsy. High frequency neural activity is important in both memory formation and seizures. Both kindling and LTP are most effectively induced by high-frequency stimuli, involve synaptic facilitation, and share overlapping molecular mechanisms, such as N-methyl-d-aspartate (NMDA) receptor-induced calcium cascade and protein synthesis. The hippocampus contributes to both through its role in memory formation and its low seizure threshold.
Collapse
Affiliation(s)
- Kimford J Meador
- Department of Neurology, University of Florida, McKnight Brain Institute, Gainesville, FL 32610, USA.
| |
Collapse
|
31
|
Kudryashov IE, Pavlova TV, Kudryashova IV, Egorova LK, Gulyaeva NV. Kindling in the early postnatal period: Effects on the dynamics of age-related changes in electrophysiological characteristics of hippocampal neurons. ACTA ACUST UNITED AC 2008; 37:765-72. [PMID: 17922240 DOI: 10.1007/s11055-007-0080-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2006] [Accepted: 05/15/2006] [Indexed: 11/25/2022]
Abstract
The effects of chronic administration of pentylenetetrazole (PTZ) during early ontogenesis (from postnatal day 14) on the dynamics of age-related changes in electrophysiological characteristics of rat hippocampal slices were studied. Unlike the situation in adult animals, convulsive activity did not develop in rat pups in response to repeated injections. Comparison of the amplitude characteristics of total monosynaptic responses of neurons in hippocampal field CA1 to application of single and paired (separated by 70 msec) stimulation of Schäffer collaterals during the period of maximally intense hippocampal synaptogenesis (at weeks 2-3 of postnatal development) revealed no significant differences between the control group (administration of isotonic saline) and the group given PTZ. The level of suppression of facilitation in paired-pulse stimulation with a short interstimulus interval (15 msec) was significantly less in hippocampal slices from rat pups from the PTZ group. However, as compared with the passive control, the direction of rearrangements in the two experimental group was essentially the same. Nonetheless, regular administration of PTZ during the period of maximally intense hippocampal maturation affected the development of its characteristics. This was not only apparent as a deficiency of inhibitory processes. Increases in the intensity of test stimuli applied to hippocampal slices from PTZ-treated rat pups at 27-48 days of age led to relatively lower response amplitudes as compared with those seen in hippocampal slices from control (given isotonic saline) rats of the same age. The level of facilitation in paired-pulse stimulation with an interstimulus interval of 70 msec showed no difference, decreasing to similar extents in both groups as compared with the passive control group. In addition, hippocampal slices from the PTZ group showed significant decreases in the magnitude of long-term potentiation. Changes occurring in the hippocampus after regular administration of PTZ did not correlate with the development of convulsive activity. The only significant relationship involving the intensity of convulsions was with the increase (compared with the normal for age) in the amplitudes of responses to minimal-intensity test stimuli.
Collapse
Affiliation(s)
- I E Kudryashov
- Institute of Higher Nervous Activity and Neurophysiology, Russian Academy of Sciences, Moscow, Russia
| | | | | | | | | |
Collapse
|
32
|
Gashi E, Avallone J, Webster T, Friedman LK. Altered excitability and distribution of NMDA receptor subunit proteins in cortical layers of rat pups following multiple perinatal seizures. Brain Res 2007; 1145:56-65. [PMID: 17320824 DOI: 10.1016/j.brainres.2007.01.110] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2006] [Revised: 01/18/2007] [Accepted: 01/29/2007] [Indexed: 11/19/2022]
Abstract
During a critical period of postnatal development the epileptogenic focus is thought to be of cortical origin. We used immunohistochemistry and Western blotting to elucidate potential mechanisms underlying an increased state of susceptibility to seizures in immature animals. Distribution patterns of N-methyl-D-aspartic acid (NMDA) (NR1 and NR2A/B) and alpha-amino-3-hydroxy-5-methyl-4-isoxazole-propionic acid (AMPA) (GluR1 and GluR2) subunits were analyzed in retrosplenial, parietal and temporal cortices during the first two postnatal weeks following three episodes of status-epilepticus. Rat pups were injected three times with kainic acid (3x KA) on P6, P9, and P13 and subsequently sacrificed 48 h after the third seizure. Cortical electroencephalography (EEG) showed increased number of spikes and bursts of longer duration after 3x KA. Immunodensity measurements after 3x KA revealed a robust increase in NR2A/B labeling specific to cortical layer V throughout the retrosplenial, parietal, and temporal cortices, with no changes noted in piriform cortex. NR1 layer V immunoreactivity was also simultaneously increased in serial sections but to a lesser degree; heightened immunodensities were specific to retrosplenial and temporal cortices. The NR1:NR2 ratio was decreased in cortical layer V of the temporal and retrosplenial cortices but not in parietal cortex despite elevated immunoreactivity. Steady levels of GluR1 and GluR2 subunits were noted in all cortical areas studied in the same animals. Thus, recurrent perinatal seizures led to selective and layer-specific increases in NMDA receptor proteins. These changes may be responsible for lowering the seizure threshold in deeper cortical areas and eventually contribute to the cortical epileptogenic focus.
Collapse
Affiliation(s)
- Eleonora Gashi
- Neuroscience Department, New York Institute of Technology, NY College of Osteopathic Medicine, Northern Boulevard, Old Westbury, NY 11568, USA
| | | | | | | |
Collapse
|
33
|
Isaeva E, Isaev D, Khazipov R, Holmes GL. Selective impairment of GABAergic synaptic transmission in the flurothyl model of neonatal seizures. Eur J Neurosci 2006; 23:1559-66. [PMID: 16553619 DOI: 10.1111/j.1460-9568.2006.04693.x] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Neonatal seizures can result in long-term adverse consequences including alteration of seizure susceptibility and impairment in spatial memory. However, little is known about the effects of neonatal seizures on developmental changes occurring in synaptic transmission during the first postnatal weeks. The purpose of the present study was to examine the effect of neonatal seizures on several aspects of gamma-aminobutyric acid (GABA)ergic and glutamatergic synaptic transmission in the developing rat hippocampus. Flurothyl was used to induce multiple recurrent seizures in rat pups during the first postnatal days. Whole-cell patch-clamp recordings from the hippocampal CA3 pyramidal cell and extracellular recordings from the CA3 pyramidal cell layer were made in slice preparations. In rats that experienced neonatal seizures the amplitude of spontaneous inhibitory postsynaptic currents at P15-17 was decreased by 27% compared with controls, whereas neither frequency nor the kinetic properties were altered. Neonatal seizures did not affect the timing of the developmental switch in the GABAA signaling from excitatory to inhibitory. None of the studied parameters of glutamatergic postsynaptic currents was different between the flurothyl and control groups, including the amplitude and frequency of the spontaneous excitatory postsynaptic currents, the ratio of the amplitudes and frequencies of the alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) and N-methyl-D-aspartate (NMDA)-mediated spontaneous postsynaptic currents, and the kinetics of AMPA and NMDA mediated postsynaptic currents in the age groups P8-10 and P15-17. We suggest that the selective depression of the amplitude of GABAergic synaptic responses may contribute to the adverse neurological and behavioral consequences that occur following neonatal seizures.
Collapse
Affiliation(s)
- Elena Isaeva
- Section of Neurology, Neuroscience Center at Dartmouth, Dartmouth Medical School, Lebanon, NH 03756, USA
| | | | | | | |
Collapse
|
34
|
Wang J, Jiang Y, Cao H, Yu L, Bo T, Ni H, Jiang Q, Wu X. Long-term effect of early discharge on sEPSC and [Ca2+]i in developing neurons. Neurosci Lett 2006; 397:104-9. [PMID: 16448748 DOI: 10.1016/j.neulet.2005.12.023] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2005] [Revised: 10/23/2005] [Accepted: 12/01/2005] [Indexed: 11/28/2022]
Abstract
To study the long-term changes induced in immature rat cortical neuronal cultures by transient exposure to an Mg(2+)-free treatment, at cultured day 6, cells were assigned into three groups, based on the mediums they were transiently exposed to as follows: control group 1 (CONT1) was exposed to Dulbecco's Modified Eagle's Medium (DMEM), control group 2 was exposed to a physiological solution (PS), and the magnesium-free physiological solution group (MGFPS) was exposed to the same medium as CONT2 except for the removal of magnesium. Following a 3-h exposure, the amplitude and frequency of spontaneous excitatory postsynaptic currents (sEPSC) were recorded and intracellular calcium concentrations ([Ca2+]i) were measured. Compared to the CONT1 and CONT2 groups, the MGFPS group displayed a significantly greater amplitude (at d6, d7, d9, and d12) and frequency (at d6, d7, and d9) of sEPSC (p<0.05). Also, both the resting and peak intracellular calcium levels were significantly greater in the MGFPS group at days 6, 7, 9, 12 and 17 (p<0.05). The rise time (time from resting level to peak level of intracellular calcium following NMDA application) was significantly shorter in the MGFPS group at culture days 7 and 17 and significantly longer at culture day 12 (p<0.05). Finally, we compared the percentage of cortical neurons expressing neuron-specific enolase (NSE) and found that there were no significant differences in the number of NSE positive neurons among three groups at days 7, 12, and 17. Our results suggests that there are long-term changes in sEPSCs and [Ca2+]i in cultured rat cortical neurons following exposure to Mg2+-free environment without cell loss.
Collapse
Affiliation(s)
- Jingmin Wang
- Department of Pediatrics, Peking University First Hospital, 100034 Beijing, China
| | | | | | | | | | | | | | | |
Collapse
|
35
|
Holmes GL. Effects of seizures on brain development: lessons from the laboratory. Pediatr Neurol 2005; 33:1-11. [PMID: 15993318 DOI: 10.1016/j.pediatrneurol.2004.12.003] [Citation(s) in RCA: 112] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/15/2004] [Revised: 12/10/2004] [Accepted: 12/28/2004] [Indexed: 10/25/2022]
Abstract
Both clinical and laboratory studies demonstrate that seizures early in life can result in permanent behavioral abnormalities and enhance epileptogenicity. In experimental rodent models, the consequences of seizures are dependent upon age, etiology, seizure duration, and frequency. Recurrent seizures in immature rats result in long-term adverse effects on learning and memory. These behavioral changes are paralleled by changes in brain connectivity, dendritic morphology, excitatory and inhibitory receptor subunits, ion channels, and neurogenesis. These changes can occur in the absence of cell loss. Although impaired cognitive function and brain changes have been well documented after early onset seizures, the mechanisms of seizure-induced injury remain unclear. Recent studies have demonstrated abnormalities in single cell function that parallel behavioral changes.
Collapse
Affiliation(s)
- Gregory L Holmes
- Neuroscience Center at Dartmouth, Section of Neurology, Dartmouth Medical School, One Medical Center Drive, Lebanon, NH 03756, USA
| |
Collapse
|
36
|
Zhao Q, Hu Y, Holmes GL. Effect of topiramate on cognitive function and activity level following neonatal seizures. Epilepsy Behav 2005; 6:529-36. [PMID: 15878305 DOI: 10.1016/j.yebeh.2005.03.001] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/30/2005] [Revised: 02/28/2005] [Accepted: 03/01/2005] [Indexed: 11/29/2022]
Abstract
Topiramate, an antiepileptic drug with a number of mechanisms of action including blockade of AMPA/KA receptor subtypes, was assessed as a neuroprotective agent following seizures. We administered topiramate or saline chronically during and following a series of 25 neonatal seizures. After completion of the topiramate treatment, animals were tested in the water maze for spatial learning and the open field for activity level. Brains were then examined for cell loss and sprouting of mossy fibers. Rats treated with topiramate performed significantly better in the water maze than rats treated with saline. Topiramate treatment also reduced the amount of seizure-induced sprouting in the supragranular region. There were no differences between topiramate- and saline-treated rats in activity level in the open field, swimming speed, or weight gain. These findings show that long-term treatment with topiramate after neonatal seizures changes the long-term consequences of seizures and improves cognitive function.
Collapse
Affiliation(s)
- Qian Zhao
- Section of Neurology, Neuroscience Center at Dartmouth, Dartmouth Medical School, Hanover, NH, USA
| | | | | |
Collapse
|
37
|
Ni H, Jiang YW, Bo T, Wang JM, Wu XR. c-Fos, N-methyl-d-aspartate receptor 2C, GABA-A-alpha1 immonoreactivity, seizure latency and neuronal injury following single or recurrent neonatal seizures in hippocampus of Wistar rat. Neurosci Lett 2005; 380:149-54. [PMID: 15854768 DOI: 10.1016/j.neulet.2005.01.043] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2004] [Revised: 01/10/2005] [Accepted: 01/11/2005] [Indexed: 11/19/2022]
Abstract
To evaluate the long-term effects of single or recurrent prolonged neonatal seizures on seizure threshold and neuronal activity in the brain, a novel "twist" seizure was induced by coupling early-life flurothyl-induced seizures with later exposure to pentylenetetrazol. The authors assigned six neonatal rats for each group: the single-seizure group (SS), the recurrent-seizure group (RS) and the control group. At postnatal day 46, seizure threshold was examined using pentylenetetrazol, and then the brain slices were evaluated with thionine staining, in situ end labeling and immunohistochemical studies. The Results showed that the rats in SS and RS groups all had reduced latencies to develop generalized tonic seizures induced by PTZ compared with controls (P<0.01). Morphologic changes, cell loss and apoptotic cells were observed only in those of RS group. Significant fos and NR2C-immunoreactive positive cells were seen in hippocampus of rats in both SS and RS groups compared with controls (P<0.01). A significant decrease in the number of GABA-A-alpha1 immunoreactive positive neurons was detected in hippocampus in rats of SS and RS groups compared with the controls (P<0.01). We conclude that neonatal rats subjected to prolonged seizures have pronounced long-term effects on seizure threshold and neuronal neurophysiological activity in the brain. Obvious neuronal injury, however, was only seen in rat with recurrent-seizures. Subtle brain damage might occur in rats experiencing single prolonged neonatal seizures.
Collapse
Affiliation(s)
- Hong Ni
- Department of Pediatrics, Peking University First Hospital, No. 8 Xishiku Street, 100034 Beijing, PR China
| | | | | | | | | |
Collapse
|