1
|
Zions M, Meehan EF, Kress ME, Thevalingam D, Jenkins EC, Kaila K, Puskarjov M, McCloskey DP. Nest Carbon Dioxide Masks GABA-Dependent Seizure Susceptibility in the Naked Mole-Rat. Curr Biol 2020; 30:2068-2077.e4. [PMID: 32359429 DOI: 10.1016/j.cub.2020.03.071] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2019] [Revised: 11/27/2019] [Accepted: 03/30/2020] [Indexed: 01/29/2023]
Abstract
African naked mole-rats were likely the first mammals to evolve eusociality, and thus required adaptations to conserve energy and tolerate the low oxygen (O2) and high carbon dioxide (CO2) of a densely populated fossorial nest. As hypercapnia is known to suppress neuronal activity, we studied whether naked mole-rats might demonstrate energy savings in GABAergic inhibition. Using whole-colony behavioral monitoring of captive naked mole-rats, we found a durable nest, characterized by high CO2 levels, where all colony members spent the majority of their time. Analysis of the naked mole-rat genome revealed, uniquely among mammals, a histidine point variation in the neuronal potassium-chloride cotransporter 2 (KCC2). A histidine missense substitution mutation at this locus in the human ortholog of KCC2, found previously in patients with febrile seizures and epilepsy, has been demonstrated to diminish neuronal Cl- extrusion capacity, and thus impairs GABAergic inhibition. Seizures were observed, without pharmacological intervention, in adult naked mole-rats exposed to a simulated hyperthermic surface environment, causing systemic hypocapnic alkalosis. Consistent with the diminished function of KCC2, adult naked mole-rats demonstrate a reduced efficacy of inhibition that manifests as triggering of seizures at room temperature by the GABAA receptor (GABAAR) positive allosteric modulator diazepam. These seizures are blocked in the presence of nest-like levels of CO2 and likely to be mediated through GABAAR activity, based on in vitro recordings. Thus, altered GABAergic inhibition adds to a growing list of adaptations in the naked mole-rat and provides a plausible proximate mechanism for nesting behavior, where a return to the colony nest restores GABA-mediated inhibition.
Collapse
Affiliation(s)
- Michael Zions
- PhD Program in Neuroscience, Graduate Center of The City University of New York, New York, NY 10016, USA; Center for Developmental Neuroscience, College of Staten Island in the City University of New York, Staten Island, NY 10314, USA
| | - Edward F Meehan
- Department of Psychology, College of Staten Island in the City University of New York, Staten Island, NY 10314, USA; Department of Computer Science, College of Staten Island in the City University of New York, Staten Island, NY 10314, USA
| | - Michael E Kress
- Department of Computer Science, College of Staten Island in the City University of New York, Staten Island, NY 10314, USA; PhD Program in Computer Science, Graduate Center of the City University of New York, New York, NY 10016, USA
| | - Donald Thevalingam
- PhD Program in Neuroscience, Graduate Center of The City University of New York, New York, NY 10016, USA; Center for Developmental Neuroscience, College of Staten Island in the City University of New York, Staten Island, NY 10314, USA
| | - Edmund C Jenkins
- Center for Developmental Neuroscience, College of Staten Island in the City University of New York, Staten Island, NY 10314, USA
| | - Kai Kaila
- Neuroscience Center (HiLIFE), University of Helsinki, Helsinki, Finland; Molecular and Integrative Biosciences, Faculty of Biological and Environmental Sciences, University of Helsinki, Helsinki, Finland
| | - Martin Puskarjov
- Center for Developmental Neuroscience, College of Staten Island in the City University of New York, Staten Island, NY 10314, USA; Molecular and Integrative Biosciences, Faculty of Biological and Environmental Sciences, University of Helsinki, Helsinki, Finland.
| | - Dan P McCloskey
- PhD Program in Neuroscience, Graduate Center of The City University of New York, New York, NY 10016, USA; Center for Developmental Neuroscience, College of Staten Island in the City University of New York, Staten Island, NY 10314, USA; Department of Psychology, College of Staten Island in the City University of New York, Staten Island, NY 10314, USA.
| |
Collapse
|
2
|
Moustaki K, Buhler E, Martinez R, Watrin F, Represa A, Manent JB. Size of Subcortical Band Heterotopia Influences the Susceptibility to Hyperthermia-Induced Seizures in a Rat Model. Front Cell Neurosci 2019; 13:473. [PMID: 31680876 PMCID: PMC6813413 DOI: 10.3389/fncel.2019.00473] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2019] [Accepted: 10/04/2019] [Indexed: 11/13/2022] Open
Abstract
Studies conducted in human and rodent models have suggested that preexisting neurodevelopmental defects could predispose immature brains to febrile seizures (FS). However, the impact of the anatomical extent of preexisting cortical malformations on FS susceptibility was never assessed. Here, we induced hyperthermic seizures (HS) in rats with bilateral subcortical band heterotopia (SBH) and found variable degrees of HS susceptibility depending on inter-individual anatomical differences in size and extent of SBH. This indicates that an association exists between the overall extent or location of a cortical malformation, and the predisposition to FS. This also suggests that various predisposing factors and underlying causes may contribute to the etiology of complex FS.
Collapse
Affiliation(s)
- Kalliopi Moustaki
- Institut de Neurobiologie de la Méditerranée INMED, INSERM UMR 1249, Aix-Marseille University, Marseille, France
| | - Emmanuelle Buhler
- Institut de Neurobiologie de la Méditerranée INMED, INSERM UMR 1249, Aix-Marseille University, Marseille, France
| | - Robert Martinez
- Institut de Neurobiologie de la Méditerranée INMED, INSERM UMR 1249, Aix-Marseille University, Marseille, France
| | - Françoise Watrin
- Institut de Neurobiologie de la Méditerranée INMED, INSERM UMR 1249, Aix-Marseille University, Marseille, France
| | - Alfonso Represa
- Institut de Neurobiologie de la Méditerranée INMED, INSERM UMR 1249, Aix-Marseille University, Marseille, France
| | - Jean-Bernard Manent
- Institut de Neurobiologie de la Méditerranée INMED, INSERM UMR 1249, Aix-Marseille University, Marseille, France
| |
Collapse
|
3
|
Barrett KT, Roy A, Rivard KB, Wilson RJ, Scantlebury MH. Vagal TRPV1 activation exacerbates thermal hyperpnea and increases susceptibility to experimental febrile seizures in immature rats. Neurobiol Dis 2018; 119:172-189. [DOI: 10.1016/j.nbd.2018.08.004] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2018] [Revised: 07/20/2018] [Accepted: 08/07/2018] [Indexed: 12/22/2022] Open
|
4
|
Barrett KT, Wilson RJA, Scantlebury MH. TRPV1 deletion exacerbates hyperthermic seizures in an age-dependent manner in mice. Epilepsy Res 2016; 128:27-34. [PMID: 27810513 DOI: 10.1016/j.eplepsyres.2016.10.016] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2016] [Revised: 09/07/2016] [Accepted: 10/24/2016] [Indexed: 01/19/2023]
Abstract
Febrile seizures (FS) are the most common seizure disorder to affect children. Although there is mounting evidence to support that FS occur when children have fever-induced hyperventilation leading to respiratory alkalosis, the underlying mechanisms of hyperthermia-induced hyperventilation and links to FS remain poorly understood. As transient receptor potential vanilloid-1 (TRPV1) receptors are heat-sensitive, play an important role in adult thermoregulation and modulate respiratory chemoreceptors, we hypothesize that TRPV1 activation is important for hyperthermia-induced hyperventilation leading to respiratory alkalosis and decreased FS thresholds, and consequently, TRPV1 KO mice will be relatively protected from hyperthermic seizures. To test our hypothesis we subjected postnatal (P) day 8-20 TRPV1 KO and C57BL/6 control mice to heated dry air. Seizure threshold temperature, latency and the rate of rise of body temperature during hyperthermia were assessed. At ages where differences in seizure thresholds were identified, head-out plethysmography was used to assess breathing and the rate of expired CO2 in response to hyperthermia, to determine if the changes in seizure thresholds were related to respiratory alkalosis. Paradoxically, we observed a pro-convulsant effect of TRPV1 deletion (∼4min decrease in seizure latency), and increased ventilation in response to hyperthermia in TRPV1 KO compared to control mice at P20. This pro-convulsant effect of TRPV1 absence was not associated with an increased rate of expired CO2, however, these mice had a more rapid rise in body temperature following exposure to hyperthermia than controls, and the expected linear relationship between body weight and seizure latency was absent. Based on these findings, we conclude that deletion of the TRPV1 receptor prevents reduction in hyperthermic seizure susceptibility in older mouse pups, via a mechanism that is independent of hyperthermia-induced respiratory alkalosis, but possibly involves impaired development of thermoregulatory mechanisms, although at present the mechanism remain unknown.
Collapse
Affiliation(s)
- Karlene T Barrett
- Department of Pediatrics, University of Calgary, 3330 Hospital Drive NW, Calgary, AB, T2N 4N1, Canada; Alberta Children's Hospital Research Institute, University of Calgary, 3330 Hospital Drive NW, Calgary, AB, T2N 4N1, Canada
| | - Richard J A Wilson
- Alberta Children's Hospital Research Institute, University of Calgary, 3330 Hospital Drive NW, Calgary, AB, T2N 4N1, Canada; Department of Physiology and Pharmacology, University of Calgary, 3330 Hospital Drive NW, Calgary, AB, T2N 4N1, Canada; Hotchkiss Brain Institute, University of Calgary, 3330 Hospital Drive NW, Calgary, AB, T2N 4N1, Canada
| | - Morris H Scantlebury
- Department of Pediatrics, University of Calgary, 3330 Hospital Drive NW, Calgary, AB, T2N 4N1, Canada; Alberta Children's Hospital Research Institute, University of Calgary, 3330 Hospital Drive NW, Calgary, AB, T2N 4N1, Canada; Department of Clinical Neuroscience, University of Calgary, 3330 Hospital Drive NW, Calgary, AB, T2N 4N1, Canada.
| |
Collapse
|
5
|
Pospelov AS, Yukin AY, Blumberg MS, Puskarjov M, Kaila K. Forebrain-independent generation of hyperthermic convulsions in infant rats. Epilepsia 2015; 57:e1-6. [PMID: 26547277 PMCID: PMC4738399 DOI: 10.1111/epi.13230] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/07/2015] [Indexed: 11/30/2022]
Abstract
Febrile seizures are the most common type of convulsive events in children. It is generally assumed that the generalization of these seizures is a result of brainstem invasion by the initial limbic seizure activity. Using precollicular transection in 13‐day‐old rats to isolate the forebrain from the brainstem, we demonstrate that the forebrain is not required for generation of tonic–clonic convulsions induced by hyperthermia or kainate. Compared with sham‐operated littermate controls, latency to onset of convulsions in both models was significantly shorter in pups that had undergone precollicular transection, indicating suppression of the brainstem seizure network by the forebrain in the intact animal. We have shown previously that febrile seizures are precipitated by hyperthermia‐induced respiratory alkalosis. Here, we show that triggering of hyperthermia‐induced hyperventilation and consequent convulsions in transected animals are blocked by diazepam. The present data suggest that the role of endogenous brainstem activity in triggering tonic–clonic seizures should be re‐evaluated in standard experimental models of limbic seizures. Our work sheds new light on the mechanisms that generate febrile seizures in children and, therefore, on how they might be treated.
Collapse
Affiliation(s)
- Alexey S Pospelov
- Department of Biosciences and Neuroscience Center, University of Helsinki, Helsinki, Finland
| | - Alexey Y Yukin
- Department of Biosciences and Neuroscience Center, University of Helsinki, Helsinki, Finland
| | - Mark S Blumberg
- Departments of Psychology and Biology, University of Iowa, Iowa City, Iowa, U.S.A
| | - Martin Puskarjov
- Department of Biosciences and Neuroscience Center, University of Helsinki, Helsinki, Finland
| | - Kai Kaila
- Department of Biosciences and Neuroscience Center, University of Helsinki, Helsinki, Finland
| |
Collapse
|
6
|
Eun BL, Abraham J, Mlsna L, Kim MJ, Koh S. Lipopolysaccharide potentiates hyperthermia-induced seizures. Brain Behav 2015; 5:e00348. [PMID: 26357586 PMCID: PMC4559014 DOI: 10.1002/brb3.348] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/07/2015] [Revised: 03/25/2015] [Accepted: 04/05/2015] [Indexed: 12/17/2022] Open
Abstract
BACKGROUND Prolonged febrile seizures (FS) have both acute and long-lasting effects on the developing brain. Because FS are often associated with peripheral infection, we aimed to develop a preclinical model of FS that simulates fever and immune activation in order to facilitate the implementation of targeted therapy after prolonged FS in young children. METHODS The innate immune activator lipopolysaccharide (LPS) was administered to postnatal day 14 rat (200 μg/kg) and mouse (100 μg/kg) pups 2-2.5 h prior to hyperthermic seizures (HT) induced by hair dryer or heat lamp. To determine whether simulation of infection enhances neuronal excitability, latency to seizure onset, threshold temperature and total number of seizures were quantified. Behavioral seizures were correlated with electroencephalographic changes in rat pups. Seizure-induced proinflammatory cytokine production was assessed in blood samples at various time points after HT. Seizure-induced microglia activation in the hippocampus was quantified using Cx3cr1(GFP/+) mice. RESULTS Lipopolysaccharide priming increased susceptibility of rats and mice to hyperthemic seizures and enhanced seizure-induced proinflammatory cytokine production and microglial activation. CONCLUSIONS Peripheral inflammation appears to work synergistically with hyperthermia to potentiate seizures and to exacerbate seizure-induced immune responses. By simulating fever, a regulated increase in body temperature from an immune challenge, we developed a more clinically relevant animal model of prolonged FS.
Collapse
Affiliation(s)
- Baik-Lin Eun
- Department of Pediatrics, Korea University College of Medicine Seoul, Korea
| | - Jayne Abraham
- Department of Pediatrics, Ann and Robert H. Lurie Children's Hospital of Chicago Stanley Manne Children's Research Institute, Northwestern University Feinberg School of Medicine Chicago, Illinois
| | - Lauren Mlsna
- Department of Pediatrics, Ann and Robert H. Lurie Children's Hospital of Chicago Stanley Manne Children's Research Institute, Northwestern University Feinberg School of Medicine Chicago, Illinois
| | - Min Jung Kim
- Department of Pediatrics, Ann and Robert H. Lurie Children's Hospital of Chicago Stanley Manne Children's Research Institute, Northwestern University Feinberg School of Medicine Chicago, Illinois
| | - Sookyong Koh
- Department of Pediatrics, Ann and Robert H. Lurie Children's Hospital of Chicago Stanley Manne Children's Research Institute, Northwestern University Feinberg School of Medicine Chicago, Illinois
| |
Collapse
|
7
|
Egri C, Ruben PC. A hot topic: temperature sensitive sodium channelopathies. Channels (Austin) 2012; 6:75-85. [PMID: 22643347 DOI: 10.4161/chan.19827] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Perturbations to body temperature affect almost all cellular processes and, within certain limits, results in minimal effects on overall physiology. Genetic mutations to ion channels, or channelopathies, can shift the fine homeostatic balance resulting in a decreased threshold to temperature induced disturbances. This review summarizes the functional consequences of currently identified voltage-gated sodium (NaV) channelopathies that lead to disorders with a temperature sensitive phenotype. A comprehensive knowledge of the relationships between genotype and environment is not only important for understanding the etiology of disease, but also for developing safe and effective treatment paradigms.
Collapse
Affiliation(s)
- Csilla Egri
- Department of Biomedical Physiology and Kinesiology; Simon Fraser University; Burnaby, BC, Canada
| | | |
Collapse
|
8
|
Vezzani A, Aronica E, Mazarati A, Pittman QJ. Epilepsy and brain inflammation. Exp Neurol 2011; 244:11-21. [PMID: 21985866 DOI: 10.1016/j.expneurol.2011.09.033] [Citation(s) in RCA: 392] [Impact Index Per Article: 30.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2011] [Revised: 09/15/2011] [Accepted: 09/26/2011] [Indexed: 02/06/2023]
Abstract
During the last decade, experimental research has demonstrated a prominent role of glial cells, activated in brain by various injuries, in the mechanisms of seizure precipitation and recurrence. In particular, alterations in the phenotype and function of activated astrocytes and microglial cells have been described in experimental and human epileptic tissue, including modifications in potassium and water channels, alterations of glutamine/glutamate cycle, changes in glutamate receptor expression and transporters, release of neuromodulatory molecules (e.g. gliotransmitters, neurotrophic factors), and induction of molecules involved in inflammatory processes (e.g. cytokines, chemokines, prostaglandins, complement factors, cell adhesion molecules) (Seifert et al., 2006; Vezzani et al., 2011; Wetherington et al., 2008). In particular, brain injury or proconvulsant events can activate microglia and astrocytes to release a number of proinflammatory mediators, thus initiating a cascade of inflammatory processes in brain tissue. Proinflammatory molecules can alter neuronal excitability and affect the physiological functions of glia by paracrine or autocrine actions, thus perturbing the glioneuronal communications. In experimental models, these changes contribute to decreasing the threshold to seizures and may compromise neuronal survival (Riazi et al., 2010; Vezzani et al., 2008). In this context, understanding which are the soluble mediators and the molecular mechanisms crucially involved in glio-neuronal interactions is instrumental to shed light on how brain inflammation may contribute to neuronal hyperexcitability in epilepsy. This review will report the clinical observations in drug-resistant human epilepsies and the experimental findings in adult and immature rodents linking brain inflammation to the epileptic process in a causal and reciprocal manner. By confronting the clinical evidence with the experimental findings, we will discuss the role of specific soluble inflammatory mediators in the etiopathogenesis of seizures, reporting evidence for both their acute and long term effects on seizure threshold. The possible contribution of these mediators to co-morbidities often described in epilepsy patients will be also discussed. Finally, we will report on the anti-inflammatory treatments with anticonvulsant actions in experimental models highlighting possible therapeutic options for treating drug-resistant seizures and for prevention of epileptogenesis.
Collapse
Affiliation(s)
- Annamaria Vezzani
- Department of Neuroscience, Mario Negri Institute for Pharmacological Research, Via G. La Masa 19, 20156 Milano, Italy.
| | | | | | | |
Collapse
|
9
|
Schuchmann S, Hauck S, Henning S, Grüters-Kieslich A, Vanhatalo S, Schmitz D, Kaila K. Respiratory alkalosis in children with febrile seizures. Epilepsia 2011; 52:1949-55. [DOI: 10.1111/j.1528-1167.2011.03259.x] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
|
10
|
Koyama R, Matsuki N. Novel etiological and therapeutic strategies for neurodiseases: mechanisms and consequences of febrile seizures: lessons from animal models. J Pharmacol Sci 2010; 113:14-22. [PMID: 20424387 DOI: 10.1254/jphs.09r19fm] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022] Open
Abstract
Febrile seizures (FS) are the most common type of convulsive events in infancy and childhood. Genetic and environmental elements have been suggested to contribute to FS. FS can be divided into simple and complex types, the former being benign, whereas it is controversial whether complex FS have an association with the development of temporal lobe epilepsy (TLE) in later life. In the hippocampus of TLE patients, several structural and functional alterations take place that render the region an epileptic foci. Thus, it is important to clarify the cellular and molecular changes in the hippocampus after FS and to determine whether they are epileptogenic. To achieve this goal, human studies are too limited because the sample tissues are only available from adult patients in the advanced and drug-resistant stages of the disease, masking the underlying etiology. These facts have inspired researchers to take advantage of well-established animal models of FS to answer the following questions: 1) How does hyperthermia induce FS? 2) Do FS induce neuroanatomical changes? 3) Do FS induce neurophysiological changes? 4) Do FS affect the behavior in later life? Here we introduce and discuss accumulating reports to answer these questions.
Collapse
Affiliation(s)
- Ryuta Koyama
- Laboratory of Chemical Pharmacology, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Japan.
| | | |
Collapse
|
11
|
Abstract
Febrile seizures (FSs) are seizures that occur during fever, usually at the time of a cold or flu, and represent the most common cause of seizures in the pediatric population. Up to 5% of children between the ages of six months and five years-of-age will experience a FS. Clinically these seizures are categorized as benign events with little impact on the growth and development of the child. However, studies have linked the occurrence of FSs to an increased risk of developing adult epileptic disorders. There are many unanswered questions about FSs, such as the mechanism of their generation, the long-term effects of these seizures, and their role in epileptogenesis. Answers are beginning to emerge based on results from animal studies. This review summarizes the current literature on animal models of FSs, mechanisms underlying the seizures, and functional, structural, and molecular changes that may result from them.
Collapse
|
12
|
Schuchmann S, Vanhatalo S, Kaila K. Neurobiological and physiological mechanisms of fever-related epileptiform syndromes. Brain Dev 2009; 31:378-82. [PMID: 19201562 DOI: 10.1016/j.braindev.2008.11.011] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/24/2008] [Revised: 10/30/2008] [Accepted: 11/04/2008] [Indexed: 10/21/2022]
Abstract
Febrile seizures (FS) are the most common type of convulsive events in children. FS have been extensively studied using animal models, where rat and mice pups are placed in a hyperthermic environment. Such work has largely focused on the consequences rather than on the mechanisms of experimental febrile seizures (eFS). We have recently shown that eFS are preceded by a dramatic rise in the rate of respiration. The consequent respiratory alkalosis affecting the brain and increasing neuronal excitability is a direct cause of the eFS [1]. If a similar mechanism contributes to human FS and other fever-related epileptiform syndromes, a number of factors operating at the molecular, cellular and systems level that have not been previously thought to be involved in their etiology must be considered. These include physiological and pathophysiological factors affecting CO(2) chemosensitivity as well as cellular and systemic mechanisms of acid-base regulation. Furthermore, a critical role for brain pH in FS points to novel types of susceptibility genes, which include genes coding pH-sensitive target proteins (e.g. neuronal ion channels) and pH-regulatory proteins. We will discuss these novel ideas and putative therapies based on them.
Collapse
Affiliation(s)
- Sebastian Schuchmann
- Department of Biological and Environmental Sciences, University of Helsinki, Helsinki, Finland
| | | | | |
Collapse
|