1
|
Yi Y, Zhong C, Wei-wei H. The long-term neurodevelopmental outcomes of febrile seizures and underlying mechanisms. Front Cell Dev Biol 2023; 11:1186050. [PMID: 37305674 PMCID: PMC10248510 DOI: 10.3389/fcell.2023.1186050] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2023] [Accepted: 05/16/2023] [Indexed: 06/13/2023] Open
Abstract
Febrile seizures (FSs) are convulsions caused by a sudden increase in body temperature during a fever. FSs are one of the commonest presentations in young children, occurring in up to 4% of children between the ages of about 6 months and 5 years old. FSs not only endanger children's health, cause panic and anxiety to families, but also have many adverse consequences. Both clinical and animal studies show that FSs have detrimental effects on neurodevelopment, that cause attention deficit hyperactivity disorder (ADHD), increased susceptibility to epilepsy, hippocampal sclerosis and cognitive decline during adulthood. However, the mechanisms of FSs in developmental abnormalities and disease occurrence during adulthood have not been determined. This article provides an overview of the association of FSs with neurodevelopmental outcomes, outlining both the underlying mechanisms and the possible appropriate clinical biomarkers, from histological changes to cellular molecular mechanisms. The hippocampus is the brain region most significantly altered after FSs, but the motor cortex and subcortical white matter may also be involved in the development disorders induced by FSs. The occurrence of multiple diseases after FSs may share common mechanisms, and the long-term role of inflammation and γ-aminobutyric acid (GABA) system are currently well studied.
Collapse
Affiliation(s)
- You Yi
- Department of Pharmacology and Department of Pharmacy of the Second Affiliated Hospital, Key Laboratory of Medical Neurobiology of the Ministry of Health of China, Zhejiang University School of Medicine, Hangzhou, China
| | - Chen Zhong
- Department of Pharmacology and Department of Pharmacy of the Second Affiliated Hospital, Key Laboratory of Medical Neurobiology of the Ministry of Health of China, Zhejiang University School of Medicine, Hangzhou, China
- Key Laboratory of Neuropharmacology and Translational Medicine of Zhejiang Province, Zhejiang Chinese Medical University, Hangzhou, China
| | - Hu Wei-wei
- Department of Pharmacology and Department of Pharmacy of the Second Affiliated Hospital, Key Laboratory of Medical Neurobiology of the Ministry of Health of China, Zhejiang University School of Medicine, Hangzhou, China
| |
Collapse
|
2
|
Hoogland G, Raijmakers M, Clynen E, Brône B, Rigo JM, Swijsen A. Experimental early-life febrile seizures cause a sustained increase in excitatory neurotransmission in newborn dentate granule cells. Brain Behav 2022; 12:e2505. [PMID: 35191203 PMCID: PMC8933791 DOI: 10.1002/brb3.2505] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/29/2021] [Revised: 11/25/2021] [Accepted: 01/02/2022] [Indexed: 11/25/2022] Open
Abstract
Prolonged febrile seizures (FS) are a risk factor for the development of hippocampal-associated temporal lobe epilepsy. The dentate gyrus is the major gateway to the hippocampal network and one of the sites in the brain where neurogenesis continues postnatally. Previously, we found that experimental FS increase the survival rate and structural integration of newborn dentate granule cells (DGCs). In addition, mature post-FS born DGCs express an altered receptor panel. Here, we aimed to study if these molecular and structural changes are accompanied by an altered cellular functioning. Experimental FS were induced by hyperthermia in 10-days-old Sprague-Dawley rats. Proliferating progenitor cells were labeled the next day by injecting green fluorescent protein expressing retroviral particles bilaterally in the dentate gyri. Eight weeks later, spontaneous excitatory and inhibitory postsynaptic events (sEPSCs and sIPSCs, respectively) were recorded from labeled DGCs using the whole-cell patch-clamp technique. Experimental FS resulted in a robust decrease of the inter event interval (p < .0001) and a small decrease of the amplitude of sEPSCs (p < .001). Collectively the spontaneous excitatory charge transfer increased (p < .01). Experimental FS also slightly increased the frequency of sIPSCs (p < .05), while the amplitude of these events decreased strongly (p < .0001). The net inhibitory charge transfer remained unchanged. Experimental, early-life FS have a long-term effect on post-FS born DGCs, as they display an increased spontaneous excitatory input when matured. It remains to be established if this presents a mechanism for FS-induced epileptogenesis.
Collapse
Affiliation(s)
- Govert Hoogland
- Department of Neurosurgery, School for Mental Health and Neuroscience, Maastricht University Medical Center, Maastricht, The Netherlands
| | - Marjolein Raijmakers
- Department of Neurosurgery, School for Mental Health and Neuroscience, Maastricht University Medical Center, Maastricht, The Netherlands.,Neurophysiology Lab, Biomedical Research Institute BIOMED, Hasselt University, Hasselt, Belgium
| | - Elke Clynen
- Neurophysiology Lab, Biomedical Research Institute BIOMED, Hasselt University, Hasselt, Belgium
| | - Bert Brône
- Neurophysiology Lab, Biomedical Research Institute BIOMED, Hasselt University, Hasselt, Belgium
| | - Jean-Michel Rigo
- Neurophysiology Lab, Biomedical Research Institute BIOMED, Hasselt University, Hasselt, Belgium
| | - Ann Swijsen
- Neurophysiology Lab, Biomedical Research Institute BIOMED, Hasselt University, Hasselt, Belgium
| |
Collapse
|
3
|
Influence of Topiramate on the Synaptic Endings of the Temporal Lobe Neocortex in an Experimental Model of Hyperthermia-Induced Seizures: An Ultrastructural Study. Brain Sci 2021; 11:brainsci11111433. [PMID: 34827435 PMCID: PMC8615765 DOI: 10.3390/brainsci11111433] [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: 09/06/2021] [Revised: 10/20/2021] [Accepted: 10/22/2021] [Indexed: 11/17/2022] Open
Abstract
The objective of this pioneering study was to assess potentially neuroprotective properties of topiramate (TPM), a broad spectrum and newer-generation antiepileptic used against damage to synaptic endings of the temporal lobe neocortex in experimental hyperthermia-induced seizures (HS). TPM (80 mg/kg b.m.) was administered in young male Wistar rats with an intragastric tube before and immediately after HS. Specimens (1 mm3) collected from the neocortex, fixed via transcardial perfusion with paraformaldehyde and glutaraldehyde solution, were routinely processed for transmission-electron microscopic study, i.e., for descriptive and morphometric analysis. The ultrastructure of neocortical neuropil components affected by hyperthermic stress showed distinct swelling of pre and post-synaptic axodendritic and axospinal endings, including total disintegration. Mitochondria were markedly damaged in synaptic structures. Axoplasm of presynaptic boutons contained a decreased number of synaptic vesicles. Synaptic junctions showed active zone-shortening. Preventive administration of TPM before HS induction demonstrated neuroprotective effects against synaptic damage in approximately 1/4 of these structures. Interestingly, beneficial effects on synapsis morphology were more common in perivascular zones close to well-preserved capillaries. They were demonstrated by smaller swelling of both presynaptic and postsynaptic parts, well-preserved mitochondria, an increased number and regular distribution of synaptic vesicles within axoplasm, and a significantly increased synaptic active zones. However, topiramate used directly after HS was ineffective in the prevention of hyperthermia-evoked synaptic injury. Our findings support the hypothesis that topiramate applied before HS can protect some neocortical synapses via the vascular factor by enhancing blood-brain barrier components and improving the blood supply of gray matter in the temporal lobe, which may be significant in febrile seizure-prevention in children.
Collapse
|
4
|
TMEM16C is involved in thermoregulation and protects rodent pups from febrile seizures. Proc Natl Acad Sci U S A 2021; 118:2023342118. [PMID: 33972431 PMCID: PMC8157992 DOI: 10.1073/pnas.2023342118] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
As the most common convulsive disorder in infancy and childhood, affecting 2 to 5% of American children in their first 5 y of life, febrile seizures (FSs) are associated with genetic risk factors, including the Tmem16c (Ano3) gene. Whereas central neuronal hyperexcitability has been implicated in FSs, whether FSs may result from compromised body temperature regulation is unknown. To approach this question, we developed rodent models of FSs associated with deficient thermoregulation, including conditional knockout mice with TMEM16C eliminated from a hypothalamic neuronal population important for maintaining body temperature but not from most of the cortical and hippocampal neurons and sensory neurons. Our findings raise the possibility that impaired homeostatic thermoregulation could contribute to the risk of FSs. Febrile seizures (FSs) are the most common convulsion in infancy and childhood. Considering the limitations of current treatments, it is important to examine the mechanistic cause of FSs. Prompted by a genome-wide association study identifying TMEM16C (also known as ANO3) as a risk factor of FSs, we showed previously that loss of TMEM16C function causes hippocampal neuronal hyperexcitability [Feenstra et al., Nat. Genet. 46, 1274–1282 (2014)]. Our previous study further revealed a reduction in the number of warm-sensitive neurons that increase their action potential firing rate with rising temperature of the brain region harboring these hypothalamic neurons. Whereas central neuronal hyperexcitability has been implicated in FSs, it is unclear whether the maximal temperature reached during fever or the rate of body temperature rise affects FSs. Here we report that mutant rodent pups with TMEM16C eliminated from all or a subset of their central neurons serve as FS models with deficient thermoregulation. Tmem16c knockout (KO) rat pups at postnatal day 10 (P10) are more susceptible to hyperthermia-induced seizures. Moreover, they display a more rapid rise of body temperature upon heat exposure. In addition, conditional knockout (cKO) mouse pups (P11) with TMEM16C deletion from the brain display greater susceptibility of hyperthermia-induced seizures as well as deficiency in thermoregulation. We also found similar phenotypes in P11 cKO mouse pups with TMEM16C deletion from Ptgds-expressing cells, including temperature-sensitive neurons in the preoptic area (POA) of the anterior hypothalamus, the brain region that controls body temperature. These findings suggest that homeostatic thermoregulation plays an important role in FSs.
Collapse
|
5
|
van Campen JS, Hessel EVS, Bohmbach K, Rizzi G, Lucassen PJ, Lakshmi Turimella S, Umeoka EHL, Meerhoff GF, Braun KPJ, de Graan PNE, Joëls M. Stress and Corticosteroids Aggravate Morphological Changes in the Dentate Gyrus after Early-Life Experimental Febrile Seizures in Mice. Front Endocrinol (Lausanne) 2018; 9:3. [PMID: 29434572 PMCID: PMC5790804 DOI: 10.3389/fendo.2018.00003] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/19/2017] [Accepted: 01/05/2018] [Indexed: 12/17/2022] Open
Abstract
Stress is the most frequently self-reported seizure precipitant in patients with epilepsy. Moreover, a relation between ear stress and epilepsy has been suggested. Although ear stress and stress hormones are known to influence seizure threshold in rodents, effects on the development of epilepsy (epileptogenesis) are still unclear. Therefore, we studied the consequences of ear corticosteroid exposure for epileptogenesis, under highly controlled conditions in an animal model. Experimental febrile seizures (eFS) were elicited in 10-day-old mice by warm-air induced hyperthermia, while a control group was exposed to a normothermic condition. In the following 2 weeks, mice received either seven corticosterone or vehicle injections or were left undisturbed. Specific measures indicative for epileptogenesis were examined at 25 days of age and compared with vehicle injected or untreated mice. We examined structural [neurogenesis, dendritic morphology, and mossy fiber sprouting (MFS)] and functional (glutamatergic postsynaptic currents and long-term potentiation) plasticity in the dentate gyrus (DG). We found that differences in DG morphology induced by eFS were aggravated by repetitive (mildly stressful) vehicle injections and corticosterone exposure. In the injected groups, eFS were associated with decreases in neurogenesis, and increases in cell proliferation, dendritic length, and spine density. No group differences were found in MFS. Despite these changes in DG morphology, no effects of eFS were found on functional plasticity. We conclude that corticosterone exposure during early epileptogenesis elicited by eFS aggravates morphological, but not functional, changes in the DG, which partly supports the hypothesis that ear stress stimulates epileptogenesis.
Collapse
Affiliation(s)
- Jolien S. van Campen
- Department of Translational Neuroscience, Brain Center Rudolf Magnus, University Medical Center Utrecht, Utrecht, Netherlands
- Department of Child Neurology, Brain Center Rudolf Magnus, University Medical Center Utrecht, Utrecht, Netherlands
| | - Ellen V. S. Hessel
- Department of Translational Neuroscience, Brain Center Rudolf Magnus, University Medical Center Utrecht, Utrecht, Netherlands
| | - Kirsten Bohmbach
- Department of Translational Neuroscience, Brain Center Rudolf Magnus, University Medical Center Utrecht, Utrecht, Netherlands
| | - Giorgio Rizzi
- Department of Translational Neuroscience, Brain Center Rudolf Magnus, University Medical Center Utrecht, Utrecht, Netherlands
| | - Paul J. Lucassen
- Swammerdam Institute for Life Sciences, Center for Neuroscience, University of Amsterdam, Amsterdam, Netherlands
| | - Sada Lakshmi Turimella
- Department of Translational Neuroscience, Brain Center Rudolf Magnus, University Medical Center Utrecht, Utrecht, Netherlands
| | - Eduardo H. L. Umeoka
- Department of Translational Neuroscience, Brain Center Rudolf Magnus, University Medical Center Utrecht, Utrecht, Netherlands
- Neursocience and Behavioral Sciences Department, Ribeirão Preto School of Medicine, University of São Paulo, Ribeirão Preto, Brazil
| | - Gideon F. Meerhoff
- Swammerdam Institute for Life Sciences, Center for Neuroscience, University of Amsterdam, Amsterdam, Netherlands
| | - Kees P. J. Braun
- Department of Child Neurology, Brain Center Rudolf Magnus, University Medical Center Utrecht, Utrecht, Netherlands
| | - Pierre N. E. de Graan
- Department of Translational Neuroscience, Brain Center Rudolf Magnus, University Medical Center Utrecht, Utrecht, Netherlands
| | - Marian Joëls
- Department of Translational Neuroscience, Brain Center Rudolf Magnus, University Medical Center Utrecht, Utrecht, Netherlands
| |
Collapse
|
6
|
Zhang X, Qu H, Wang Y, Zhao S, Xiao T, Zhao C, Teng W. Aberrant plasticity in the hippocampus after neonatal seizures. Int J Neurosci 2017; 128:384-391. [PMID: 28937832 DOI: 10.1080/00207454.2017.1384380] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Affiliation(s)
- Xiaoqian Zhang
- Department of Neurology, The First Hospital of China Medical University, Shenyang, Liaoning, PR China
| | - Huiling Qu
- Department of Neurology, The People's Hospital of China Medical University, Shenyang, Liaoning, PR China
| | - Ying Wang
- Department of Neurology, The First Hospital of Dalian Medical University, Dalian, Liaoning, PR China
| | - Shanshan Zhao
- Department of Neurology, The First Hospital of China Medical University, Shenyang, Liaoning, PR China
| | - Ting Xiao
- Department of Dermatology, The First Hospital of China Medical University, Shenyang, Liaoning, PR China
- Key Laboratory of Immunodermatology, Ministry of Health, Ministry of Education, Shenyang, Liaoning, PR China
| | - Chuansheng Zhao
- Department of Neurology, The First Hospital of China Medical University, Shenyang, Liaoning, PR China
| | - Weiyu Teng
- Department of Neurology, The First Hospital of China Medical University, Shenyang, Liaoning, PR China
| |
Collapse
|
7
|
Yu YH, Lee K, Sin DS, Park KH, Park DK, Kim DS. Altered functional efficacy of hippocampal interneuron during epileptogenesis following febrile seizures. Brain Res Bull 2017; 131:25-38. [DOI: 10.1016/j.brainresbull.2017.02.009] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2016] [Revised: 02/17/2017] [Accepted: 02/23/2017] [Indexed: 12/22/2022]
|
8
|
Feng B, Chen Z. Generation of Febrile Seizures and Subsequent Epileptogenesis. Neurosci Bull 2016; 32:481-92. [PMID: 27562688 DOI: 10.1007/s12264-016-0054-5] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2016] [Accepted: 07/13/2016] [Indexed: 11/24/2022] Open
Abstract
Febrile seizures (FSs) occur commonly in children aged from 6 months to 5 years. Complex (repetitive or prolonged) FSs, but not simple FSs, can lead to permanent brain modification. Human infants and immature rodents that have experienced complex FSs have a high risk of subsequent temporal lobe epilepsy. However, the causes of FSs and the mechanisms underlying the subsequent epileptogenesis remain unknown. Here, we mainly focus on two major questions concerning FSs: how fever triggers seizures, and how epileptogenesis occurs after FSs. The risk factors responsible for the occurrence of FSs and the epileptogenesis after prolonged FSs are thoroughly summarized and discussed. An understanding of these factors can provide potential therapeutic targets for the prevention of FSs and also yield biomarkers for identifying patients at risk of epileptogenesis following FSs.
Collapse
Affiliation(s)
- Bo Feng
- Department of Pharmacology, Key Laboratory of Medical Neurobiology of the Ministry of Health of China, School of Medicine, Zhejiang University, Hangzhou, 310058, China
| | - Zhong Chen
- Department of Pharmacology, Key Laboratory of Medical Neurobiology of the Ministry of Health of China, School of Medicine, Zhejiang University, Hangzhou, 310058, China.
| |
Collapse
|
9
|
Raijmakers M, Clynen E, Smisdom N, Nelissen S, Brône B, Rigo JM, Hoogland G, Swijsen A. Experimental febrile seizures increase dendritic complexity of newborn dentate granule cells. Epilepsia 2016; 57:717-26. [PMID: 27020476 DOI: 10.1111/epi.13357] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/18/2016] [Indexed: 01/19/2023]
Abstract
OBJECTIVE Febrile seizures (FS) are fever-associated convulsions, being the most common seizure disorder in early childhood. A subgroup of these children later develops epilepsy characterized by a hyperexcitable neuronal network in the hippocampus. Hippocampal excitability is regulated by the hippocampal dentate gyrus (DG) where postnatal neurogenesis occurs. Experimental FS increase the survival of newborn hippocampal dentate granule cells (DGCs), yet the significance of this neuronal subpopulation to the hippocampal network remains unclear. In the current study, we characterized the temporal maturation and structural integration of these post-FS born DGCs in the DG. METHODS Experimental FS were induced in 10-day-old rat pups. The next day, retroviral particles coding for enhanced green fluorescent protein (eGFP) were stereotactically injected in the DG to label newborn cells. Histochemical analyses of eGFP expressing DGCs were performed one, 4, and 8 weeks later and consisted of the following: (1) colocalization with neurodevelopmental markers doublecortin, calretinin, and the mature neuronal marker NeuN; (2) quantification of dendritic complexity; and (3) quantification of spine density and morphology. RESULTS At neither time point were neurodevelopmental markers differently expressed between FS animals and normothermia (NT) controls. One week after treatment, DGCs from FS animals showed dendrites that were 66% longer than those from NT controls. At 4 and 8 weeks, Sholl analysis of the outer 83% of the molecular layer showed 20-25% more intersections in FS animals than in NT controls (p < 0.01). Although overall spine density was not affected, an increase in mushroom-type spines was observed after 8 weeks. SIGNIFICANCE Experimental FS increase dendritic complexity and the number of mushroom-type spines in post-FS born DGCs, demonstrating a more mature phenotype and suggesting increased incoming excitatory information. The consequences of this hyperconnectivity to signal processing in the DG and the output of the hippocampus remain to be studied.
Collapse
Affiliation(s)
- Marjolein Raijmakers
- Biomedical Research Institute BIOMED, Hasselt University, Hasselt, Belgium.,Department of Neurosurgery, School for Mental Health and Neuroscience, Maastricht University Medical Center, Maastricht, The Netherlands
| | - Elke Clynen
- Biomedical Research Institute BIOMED, Hasselt University, Hasselt, Belgium
| | - Nick Smisdom
- Biomedical Research Institute BIOMED, Hasselt University, Hasselt, Belgium.,Flemish Institute for Technological Research, Environmental Risk and Health Unit, Mol, Belgium
| | - Sofie Nelissen
- Biomedical Research Institute BIOMED, Hasselt University, Hasselt, Belgium
| | - Bert Brône
- Biomedical Research Institute BIOMED, Hasselt University, Hasselt, Belgium
| | - Jean-Michel Rigo
- Biomedical Research Institute BIOMED, Hasselt University, Hasselt, Belgium
| | - Govert Hoogland
- Department of Neurosurgery, School for Mental Health and Neuroscience, Maastricht University Medical Center, Maastricht, The Netherlands
| | - Ann Swijsen
- Biomedical Research Institute BIOMED, Hasselt University, Hasselt, Belgium
| |
Collapse
|
10
|
Scharfman HE, Brooks-Kayal AR. Is plasticity of GABAergic mechanisms relevant to epileptogenesis? ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2014; 813:133-50. [PMID: 25012373 DOI: 10.1007/978-94-017-8914-1_11] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Numerous changes in GABAergic neurons, receptors, and inhibitory mechanisms have been described in temporal lobe epilepsy (TLE), either in humans or in animal models. Nevertheless, there remains a common assumption that epilepsy can be explained by simply an insufficiency of GABAergic inhibition. Alternatively, investigators have suggested that there is hyperinhibition that masks an underlying hyperexcitability. Here we examine the status epilepticus (SE) models of TLE and focus on the dentate gyrus of the hippocampus, where a great deal of data have been collected. The types of GABAergic neurons and GABAA receptors are summarized under normal conditions and after SE. The role of GABA in development and in adult neurogenesis is discussed. We suggest that instead of "too little or too much" GABA there is a complexity of changes after SE that makes the emergence of chronic seizures (epileptogenesis) difficult to understand mechanistically, and difficult to treat. We also suggest that this complexity arises, at least in part, because of the remarkable plasticity of GABAergic neurons and GABAA receptors in response to insult or injury.
Collapse
Affiliation(s)
- Helen E Scharfman
- The Nathan S. Kline Institute for Psychiatric Research, Orangeburg, NY, USA,
| | | |
Collapse
|
11
|
Laurén HB, Ruohonen S, Kukko-Lukjanov TK, Virta JE, Grönman M, Lopez-Picon FR, Järvelä JT, Holopainen IE. Status epilepticus alters neurogenesis and decreases the number of GABAergic neurons in the septal dentate gyrus of 9-day-old rats at the early phase of epileptogenesis. Brain Res 2013; 1516:33-44. [PMID: 23623775 DOI: 10.1016/j.brainres.2013.04.028] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2012] [Revised: 03/20/2013] [Accepted: 04/14/2013] [Indexed: 01/03/2023]
Abstract
The effects of a prolonged seizure, i.e. status epilepticus (SE), on neurogenesis of dentate granule cells (DGCs) in the immature dentate gyrus (DG) and possible changes in the phenotypes of the newborn neurons have remained incompletely characterized. We have now studied neurogenesis of DGCs in 9-day-old (postnatal, P9) rats 1 week after kainate (KA)-induced SE using 5-bromo-2-deoxyuridine (BrdU) immunostaining. The phenotype characterization of the newborn cells was carried out by immunofluorescence double labeling using doublecortin (DCX) and nestin as markers for immature cells, and glial fibrillary acid protein (GFAP) as a marker for glial cells. Newborn GABAergic neurons were further identified with antibodies for parvalbumin, glutamate decarboxylase 67 (GAD67), and the GABAA receptor α1 subunit, and mRNA expression of GABAergic and immature neurons was measured with quantitative real-time PCR (qPCR) in the DG. Our results show that the number of newborn as well as GABAergic neurons was significantly decreased after SE in the superior blade of the septal DG. The majority of the newborn BrdU-stained neurons co-expressed DCX, but neither nestin nor GFAP. In both experimental groups, newborn neurons were frequently localized in close contact, but not co-localized, with the cells positively stained for the GABAergic cell markers. Nestin and calretinin mRNA expression were significantly increased after SE. Our results suggest that SE-induced disruption of DGC neurogenesis and decreased number of GABAergic neurons could modify the connectivity between these cells and disturb the maturation of the GABAergic neurotransmission in the immature DG at the early epileptogenic phase.
Collapse
Affiliation(s)
- H B Laurén
- Department of Pharmacology, Drug Development and Therapeutics, Itäinen Pitkäkatu 4 B, 20014 University of Turku, Finland
| | | | | | | | | | | | | | | |
Collapse
|
12
|
Swijsen A, Nelissen K, Janssen D, Rigo JM, Hoogland G. Validation of reference genes for quantitative real-time PCR studies in the dentate gyrus after experimental febrile seizures. BMC Res Notes 2012; 5:685. [PMID: 23237195 PMCID: PMC3598510 DOI: 10.1186/1756-0500-5-685] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2012] [Accepted: 09/24/2012] [Indexed: 01/25/2023] Open
Abstract
BACKGROUND Quantitative real-time PCR (qPCR) is a commonly used technique to quantify gene expression levels. Validated normalization is essential to obtain reliable qPCR data. In that context, normalizing to multiple reference genes has become the most popular method. However, expression of reference genes may vary per tissue type, developmental stage and in response to experimental treatment. It is therefore imperative to determine stable reference genes for a specific sample set and experimental model. The present study was designed to validate potential reference genes in hippocampal tissue from rats that had experienced early-life febrile seizures (FS). To this end, we applied an established model in which FS were evoked by exposing 10-day old rat pups to heated air. One week later, we determined the expression stability of seven frequently used reference genes in the hippocampal dentate gyrus. RESULTS Gene expression stability of 18S rRNA, ActB, GusB, Arbp, Tbp, CycA and Rpl13A was tested using geNorm and Normfinder software. The ranking order of reference genes proposed by geNorm was not identical to that suggested by Normfinder. However, both algorithms indicated CycA, Rpl13A and Tbp as the most stable genes, whereas 18S rRNA and ActB were found to be the least stably expressed genes. CONCLUSIONS Our data demonstrate that the geometric averaging of at least CycA, Rpl13A and Tbp allows reliable interpretation of gene expression data in this experimental set-up. The results also show that ActB and 18S rRNA are not suited as reference genes in this model.
Collapse
Affiliation(s)
- Ann Swijsen
- BIOMED Research Institute, Hasselt University and transnational University Limburg, Agoralaan Bld C, 3590, Diepenbeek, Belgium
| | | | | | | | | |
Collapse
|
13
|
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
|