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Pallud J, Le Van Quyen M, Bielle F, Pellegrino C, Varlet P, Cresto N, Baulac M, Duyckaerts C, Kourdougli N, Chazal G, Devaux B, Rivera C, Miles R, Capelle L, Huberfeld G. Cortical GABAergic excitation contributes to epileptic activities around human glioma. Sci Transl Med 2015; 6:244ra89. [PMID: 25009229 DOI: 10.1126/scitranslmed.3008065] [Citation(s) in RCA: 191] [Impact Index Per Article: 21.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Brain gliomas are highly epileptogenic. Excitatory glutamatergic mechanisms are involved in the generation of epileptic activities in the neocortex surrounding gliomas. However, chloride homeostasis is known to be perturbed in glioma cells. Thus, the contribution of γ-aminobutyric acidergic (GABAergic) mechanisms that depend on intracellular chloride merits closer study. We studied the occurrence, networks, cells, and signaling basis of epileptic activities in neocortical slices from the peritumoral surgical margin resected around human brain gliomas. Postoperative glioma tissue from 69% of patients spontaneously generated interictal-like discharges, synchronized, with a high-frequency oscillation signature, in superficial layers of neocortex around areas of glioma infiltration. Interictal-like events depended both on glutamatergic AMPA receptor-mediated transmission and on depolarizing GABAergic signaling. GABA released by interneurons depolarized 65% of pyramidal cells, in which chloride homeostasis was perturbed because of changes in expression of neuronal chloride cotransporters: KCC2 (K-Cl cotransporter 2) was reduced by 42% and expression of NKCC1 (Na-K-2Cl cotransporter 1) increased by 144%. Ictal-like activities were initiated by convulsant stimuli exclusively in these epileptogenic areas. This study shows that epileptic activities are sustained by excitatory effects of GABA in human peritumoral neocortex, as reported in temporal lobe epilepsies, suggesting that both glutamate and GABA signaling and cellular chloride regulation processes, all also involved in oncogenesis as already shown, induce an imbalance between synaptic excitation and inhibition underlying epileptic discharges in glioma patients. Thus, the control of chloride in neurons and glioma cells may provide a therapeutic target for patients with epileptogenic gliomas.
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Affiliation(s)
- Johan Pallud
- Institut du Cerveau et de la Moelle Epinière, INSERM UMRS975, CNRS UMR7225, Université Pierre et Marie Curie (UPMC), Paris, France.,Service de Neurochirurgie, Centre Hospitalier Sainte-Anne, Paris, France.,Université Paris Descartes, France
| | - Michel Le Van Quyen
- Institut du Cerveau et de la Moelle Epinière, INSERM UMRS975, CNRS UMR7225, Université Pierre et Marie Curie (UPMC), Paris, France
| | - Franck Bielle
- Service de Neuropathologie, Centre Hospitalo-Universitaire Pitié-Salpêtrière, Assistance Publique - Hôpitaux de Paris (AP-HP), Paris, France
| | - Christophe Pellegrino
- INMED, Parc Scientifique de Luminy, Marseille, France.,Université de la Méditerranée, UMR S901 Aix-Marseille Université, Marseille, France
| | - Pascale Varlet
- Service de Neuropathologie, Centre Hospitalier Sainte-Anne, Paris, France
| | - Noemie Cresto
- Institut du Cerveau et de la Moelle Epinière, INSERM UMRS975, CNRS UMR7225, Université Pierre et Marie Curie (UPMC), Paris, France
| | - Michel Baulac
- Institut du Cerveau et de la Moelle Epinière, INSERM UMRS975, CNRS UMR7225, Université Pierre et Marie Curie (UPMC), Paris, France.,Unité d'Epileptologie, Centre Hospitalo-Universitaire Pitié-Salpêtrière, Assistance Publique - Hôpitaux de Paris (AP-HP), Paris, France
| | - Charles Duyckaerts
- Service de Neuropathologie, Centre Hospitalo-Universitaire Pitié-Salpêtrière, Assistance Publique - Hôpitaux de Paris (AP-HP), Paris, France
| | - Nazim Kourdougli
- INMED, Parc Scientifique de Luminy, Marseille, France.,Université de la Méditerranée, UMR S901 Aix-Marseille Université, Marseille, France
| | - Geneviève Chazal
- INMED, Parc Scientifique de Luminy, Marseille, France.,Université de la Méditerranée, UMR S901 Aix-Marseille Université, Marseille, France
| | - Bertrand Devaux
- Service de Neurochirurgie, Centre Hospitalier Sainte-Anne, Paris, France.,Université Paris Descartes, France
| | - Claudio Rivera
- INMED, Parc Scientifique de Luminy, Marseille, France.,Université de la Méditerranée, UMR S901 Aix-Marseille Université, Marseille, France.,Neuroscience Center, University of Helsinki, Finland
| | - Richard Miles
- Institut du Cerveau et de la Moelle Epinière, INSERM UMRS975, CNRS UMR7225, Université Pierre et Marie Curie (UPMC), Paris, France
| | - Laurent Capelle
- Institut du Cerveau et de la Moelle Epinière, INSERM UMRS975, CNRS UMR7225, Université Pierre et Marie Curie (UPMC), Paris, France.,Service de Neurochirurgie, Centre Hospitalo-Universitaire Pitié-Salpêtrière, Assistance Publique - Hôpitaux de Paris (AP-HP), Paris, France
| | - Gilles Huberfeld
- Institut du Cerveau et de la Moelle Epinière, INSERM UMRS975, CNRS UMR7225, Université Pierre et Marie Curie (UPMC), Paris, France.,Service de Neuropathologie, Centre Hospitalo-Universitaire Pitié-Salpêtrière, Assistance Publique - Hôpitaux de Paris (AP-HP), Paris, France.,Unité d'Epileptologie, Centre Hospitalo-Universitaire Pitié-Salpêtrière, Assistance Publique - Hôpitaux de Paris (AP-HP), Paris, France.,Département de Neurophysiologie, UPMC, Centre Hospitalo-Universitaire Pitié-Salpêtrière, Assistance Publique - Hôpitaux de Paris (AP-HP), Paris, France
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152
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Huberfeld G, Blauwblomme T, Miles R. Hippocampus and epilepsy: Findings from human tissues. Rev Neurol (Paris) 2015; 171:236-51. [PMID: 25724711 PMCID: PMC4409112 DOI: 10.1016/j.neurol.2015.01.563] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2014] [Accepted: 01/20/2015] [Indexed: 11/18/2022]
Abstract
Surgical removal of the epileptogenic zone provides an effective therapy for several focal epileptic syndromes. This surgery offers the opportunity to study pathological activity in living human tissue for pharmacoresistant partial epilepsy syndromes including temporal lobe epilepsies with hippocampal sclerosis, cortical dysplasias, epilepsies associated with tumors and developmental malformations. Slices of tissue from patients with these syndromes retain functional neuronal networks and may generate epileptic activities. The properties of cells in this tissue may not be greatly changed, but excitatory synaptic transmission is often enhanced and GABAergic inhibition is preserved. Typically epileptic activity is not generated spontaneously by the neocortex, whether dysplastic or not, but can be induced by convulsants. The initiation of ictal discharges in the neocortex depends on both GABAergic signaling and increased extracellular potassium. In contrast, a spontaneous interictal-like activity is generated by tissues from patients with temporal lobe epilepsies associated with hippocampal sclerosis. This activity is initiated, not in the hippocampus but in the subiculum, an output region, which projects to the entorhinal cortex. Interictal events seem to be triggered by GABAergic cells, which paradoxically excite about 20% of subicular pyramidal cells while simultaneously inhibiting the majority. Interictal discharges thus depend on both GABAergic and glutamatergic signaling. The depolarizing effects of GABA depend on a pathological elevation in levels of chloride in some subicular cells, similar to those of developmentally immature cells. Such defect is caused by a perturbed expression of the cotransporters regulating intracellular chloride concentration, the importer NKCC1 and the extruder KCC2. Blockade of NKCC1 actions by the diuretic bumetanide restores intracellular chloride and thus hyperpolarizing GABAergic actions and consequently suppressing interictal activity.
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Affiliation(s)
- G Huberfeld
- Département de neurophysiologie, Sorbonne universités, UPMC - université Paris 06, UPMC, CHU de la Pitié-Salpêtrière, 47-83, boulevard de l'Hôpital, 75013 Paris, France; INSERM Unit U1129 Infantile Epilepsies and Brain Plasticity, University Paris Descartes, Sorbonne Paris Cité, CEA, 12, rue de l'École-de-Médecine, 75006 Paris, France.
| | - T Blauwblomme
- INSERM Unit U1129 Infantile Epilepsies and Brain Plasticity, University Paris Descartes, Sorbonne Paris Cité, CEA, 12, rue de l'École-de-Médecine, 75006 Paris, France; Neurosurgery Department, Necker-Enfants Malades Hospital, University Paris Descartes, PRES Sorbonne Paris Cité, 12, rue de l'École-de-Médecine, 75006 Paris, France
| | - R Miles
- Inserm U1127, CNRS UMR7225, Sorbonne universités, UPMC - université Paris 6 UMR S1127, Institut du cerveau et de la moelle épinière, 47, boulevard de l'Hôpital, 75013 Paris, France
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153
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Lai KP, Li JW, Wang SY, Chiu JMY, Tse A, Lau K, Lok S, Au DWT, Tse WKF, Wong CKC, Chan TF, Kong RYC, Wu RSS. Tissue-specific transcriptome assemblies of the marine medaka Oryzias melastigma and comparative analysis with the freshwater medaka Oryzias latipes. BMC Genomics 2015; 16:135. [PMID: 25765076 PMCID: PMC4352242 DOI: 10.1186/s12864-015-1325-7] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2014] [Accepted: 02/06/2015] [Indexed: 11/12/2022] Open
Abstract
Background The marine medaka Oryzias melastigma has been demonstrated as a novel model for marine ecotoxicological studies. However, the lack of genome and transcriptome reference has largely restricted the use of O. melastigma in the assessment of in vivo molecular responses to environmental stresses and the analysis of biological toxicity in the marine environment. Although O. melastigma is believed to be phylogenetically closely related to Oryzias latipes, the divergence between these two species is still largely unknown. Using Illumina high-throughput RNA sequencing followed by de novo assembly and comprehensive gene annotation, we provided transcriptomic resources for the brain, liver, ovary and testis of O. melastigma. We also investigated the possible extent of divergence between O. melastigma and O. latipes at the transcriptome level. Results More than 14,000 transcripts across brain, liver, ovary and testis in marine medaka were annotated, of which 5880 transcripts were orthologous between O. melastigma and O. latipes. Tissue-enriched genes were identified in O. melastigma, and Gene Ontology analysis demonstrated the functional specificity of the annotated genes in respective tissue. Lastly, the identification of marine medaka-enriched transcripts suggested the necessity of generating transcriptome dataset of O. melastigma. Conclusions Orthologous transcripts between O. melastigma and O. latipes, tissue-enriched genes and O. melastigma-enriched transcripts were identified. Genome-wide expression studies of marine medaka require an assembled transcriptome, and this sequencing effort has generated a valuable resource of coding DNA for a non-model species. This transcriptome resource will aid future studies assessing in vivo molecular responses to environmental stresses and those analyzing biological toxicity in the marine environment. Electronic supplementary material The online version of this article (doi:10.1186/s12864-015-1325-7) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Keng Po Lai
- School of Biological Sciences, Kadoorie Biological Sciences Building, The University of Hong Kong, Pokfulam Road, Hong Kong, SAR, China. .,The State Key Laboratory in Marine Pollution, Hong Kong, China.
| | - Jing-Woei Li
- School of Life Sciences, Hong Kong Bioinformatics Centre, The Chinese University of Hong Kong, Hong Kong, SAR, China.
| | - Simon Yuan Wang
- School of Biological Sciences, Kadoorie Biological Sciences Building, The University of Hong Kong, Pokfulam Road, Hong Kong, SAR, China. .,The State Key Laboratory in Marine Pollution, Hong Kong, China.
| | - Jill Man-Ying Chiu
- Department of Biology, Hong Kong Baptist University, Hong Kong, SAR, China. .,The State Key Laboratory in Marine Pollution, Hong Kong, China.
| | - Anna Tse
- School of Biological Sciences, Kadoorie Biological Sciences Building, The University of Hong Kong, Pokfulam Road, Hong Kong, SAR, China. .,The State Key Laboratory in Marine Pollution, Hong Kong, China.
| | - Karen Lau
- School of Biological Sciences, Kadoorie Biological Sciences Building, The University of Hong Kong, Pokfulam Road, Hong Kong, SAR, China. .,The State Key Laboratory in Marine Pollution, Hong Kong, China.
| | - Si Lok
- Genome Research Centre, The Hong Kong Jockey Club Building for Interdisciplinary Research, The University of Hong Kong, 5 Sassoon Road, Pokfulam, Hong Kong, SAR, China.
| | - Doris Wai-Ting Au
- Department of Biology and Chemistry, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong, SAR, China. .,The State Key Laboratory in Marine Pollution, Hong Kong, China.
| | - William Ka-Fai Tse
- Department of Biology, Hong Kong Baptist University, Hong Kong, SAR, China.
| | - Chris Kong-Chu Wong
- Department of Biology, Hong Kong Baptist University, Hong Kong, SAR, China. .,The State Key Laboratory in Marine Pollution, Hong Kong, China.
| | - Ting-Fung Chan
- School of Life Sciences, Hong Kong Bioinformatics Centre, The Chinese University of Hong Kong, Hong Kong, SAR, China.
| | - Richard Yuen-Chong Kong
- Department of Biology and Chemistry, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong, SAR, China. .,The State Key Laboratory in Marine Pollution, Hong Kong, China.
| | - Rudolf Shiu-Sun Wu
- School of Biological Sciences, Kadoorie Biological Sciences Building, The University of Hong Kong, Pokfulam Road, Hong Kong, SAR, China. .,The State Key Laboratory in Marine Pollution, Hong Kong, China.
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154
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Choe KY, Han SY, Gaub P, Shell B, Voisin DL, Knapp BA, Barker PA, Brown CH, Cunningham JT, Bourque CW. High salt intake increases blood pressure via BDNF-mediated downregulation of KCC2 and impaired baroreflex inhibition of vasopressin neurons. Neuron 2015; 85:549-60. [PMID: 25619659 PMCID: PMC4577058 DOI: 10.1016/j.neuron.2014.12.048] [Citation(s) in RCA: 94] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2013] [Revised: 11/10/2014] [Accepted: 12/17/2014] [Indexed: 01/03/2023]
Abstract
The mechanisms by which dietary salt promotes hypertension are unknown. Previous work established that plasma [Na(+)] and osmolality rise in proportion with salt intake and thus promote release of vasopressin (VP) from the neurohypophysis. Although high levels of circulating VP can increase blood pressure, this effect is normally prevented by a potent GABAergic inhibition of VP neurons by aortic baroreceptors. Here we show that chronic high salt intake impairs baroreceptor inhibition of rat VP neurons through a brain-derived neurotrophic factor (BDNF)-dependent activation of TrkB receptors and downregulation of KCC2 expression, which prevents inhibitory GABAergic signaling. We show that high salt intake increases the spontaneous firing rate of VP neurons in vivo and that circulating VP contributes significantly to the elevation of arterial pressure under these conditions. These results provide the first demonstration that dietary salt can affect blood pressure through neurotrophin-induced plasticity in a central homeostatic circuit.
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Affiliation(s)
- Katrina Y Choe
- Centre for Research in Neuroscience, Research Institute of the McGill University Health Centre, 1650 Cedar Avenue, Montreal, QC H3G1A4, Canada
| | - Su Y Han
- Centre for Neuroendocrinology and Department of Physiology, University of Otago, Dunedin 9054, New Zealand
| | - Perrine Gaub
- Montreal Neurological Institute, 3801 University Street, Montreal, QC H3A2B4, Canada
| | - Brent Shell
- Department of Integrative Physiology, University of North Texas Health Sciences Centre, 3500 Camp Bowie Boulevard, Fort Worth, TX 76107, USA
| | - Daniel L Voisin
- Neurocentre Magendie, INSERM U862, 146, rue Léo Saignat, 33077 Bordeaux, France
| | - Blayne A Knapp
- Department of Integrative Physiology, University of North Texas Health Sciences Centre, 3500 Camp Bowie Boulevard, Fort Worth, TX 76107, USA
| | - Philip A Barker
- Montreal Neurological Institute, 3801 University Street, Montreal, QC H3A2B4, Canada
| | - Colin H Brown
- Centre for Neuroendocrinology and Department of Physiology, University of Otago, Dunedin 9054, New Zealand
| | - J Thomas Cunningham
- Department of Integrative Physiology, University of North Texas Health Sciences Centre, 3500 Camp Bowie Boulevard, Fort Worth, TX 76107, USA
| | - Charles W Bourque
- Centre for Research in Neuroscience, Research Institute of the McGill University Health Centre, 1650 Cedar Avenue, Montreal, QC H3G1A4, Canada.
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155
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Semaan S, Wu J, Gan Y, Jin Y, Li GH, Kerrigan JF, Chang YC, Huang Y. Hyperactivation of BDNF-TrkB signaling cascades in human hypothalamic hamartoma (HH): a potential mechanism contributing to epileptogenesis. CNS Neurosci Ther 2015; 21:164-72. [PMID: 25307426 PMCID: PMC6495156 DOI: 10.1111/cns.12331] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2014] [Revised: 08/20/2014] [Accepted: 09/04/2014] [Indexed: 01/26/2023] Open
Abstract
AIMS Although compelling evidence suggests that human hypothalamic hamartoma (HH) is intrinsically epileptogenic for gelastic seizures, the molecular mechanisms responsible for epileptogenesis within HH remain to be elucidated. The aim of this study was to test the hypothesis that hyperactivation of BDNF-TrkB signaling pathways in surgically resected HH tissue is a possible mechanism for downregulation of KCC2 expression, which in turn underlies GABA-mediated excitation within HH. METHODS Activation of three major BDNF-TrkB signaling pathways including MAPKs, Akt, and PLCγ1 were evaluated in surgically resected HH tissue (n = 14) versus human hypothalamic control tissue (n = 8) using combined methodologies of biochemistry, molecular biology, cell biology, and electrophysiology. RESULTS Our data show that compared with hypothalamic control tissue, in HH tissue, (i) activation of TrkB and expression of mature BDNF are elevated; (ii) MAPKs (including ERK1/2, p38, and JNK), Akt, and PLCγ1 are highly activated; (iii) KCC2 expression is downregulated; and (iv) pharmacological manipulation of TrkB signaling alters HH neuronal firing rate. CONCLUSION Our findings suggest that multiple BDNF-TrkB signaling pathways are activated in HH. They act independently or collaboratively to downregulate KCC2 expression, which is the key component for GABA-mediated excitation associated with gelastic seizures.
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Affiliation(s)
- Suzan Semaan
- St. Joseph's Hospital and Medical Center, Phoenix, AZ, USA
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156
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Puskarjov M, Ahmad F, Khirug S, Sivakumaran S, Kaila K, Blaesse P. BDNF is required for seizure-induced but not developmental up-regulation of KCC2 in the neonatal hippocampus. Neuropharmacology 2015; 88:103-9. [PMID: 25229715 DOI: 10.1016/j.neuropharm.2014.09.005] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2014] [Revised: 09/01/2014] [Accepted: 09/04/2014] [Indexed: 01/21/2023]
Abstract
A robust increase in the functional expression of the neuronal K-Cl cotransporter KCC2 during CNS development is necessary for the emergence of hyperpolarizing ionotropic GABAergic transmission. BDNF-TrkB signaling has been implicated in the developmental up-regulation of KCC2 and, in mature animals, in fast activity-dependent down-regulation of KCC2 function following seizures and trauma. In contrast to the decrease in KCC2 expression observed in the adult hippocampus following trauma, seizures in the neonate trigger a TrkB-dependent up-regulation of neuronal Cl(-) extrusion capacity associated with enhanced surface expression of KCC2. Here, we show that this effect is transient, and impaired in the hippocampus of Bdnf(-/-) mice. Notably, however, a complete absence of BDNF does not compromise the increase in KCC2 protein or K-Cl transport functionality during neuronal development. Furthermore, we present data indicating that the functional up-regulation of KCC2 by neonatal seizures is temporally limited by calpain activity.
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Affiliation(s)
- Martin Puskarjov
- Department of Biosciences and Neuroscience Center, University of Helsinki, FI-00014 Helsinki, Finland
| | - Faraz Ahmad
- Department of Biosciences and Neuroscience Center, University of Helsinki, FI-00014 Helsinki, Finland
| | - Stanislav Khirug
- Department of Biosciences and Neuroscience Center, University of Helsinki, FI-00014 Helsinki, Finland
| | - Sudhir Sivakumaran
- Department of Biosciences and Neuroscience Center, University of Helsinki, FI-00014 Helsinki, Finland
| | - Kai Kaila
- Department of Biosciences and Neuroscience Center, University of Helsinki, FI-00014 Helsinki, Finland
| | - Peter Blaesse
- Department of Biosciences and Neuroscience Center, University of Helsinki, FI-00014 Helsinki, Finland.
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157
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MacKenzie G, Maguire J. Chronic stress shifts the GABA reversal potential in the hippocampus and increases seizure susceptibility. Epilepsy Res 2015; 109:13-27. [PMID: 25524838 PMCID: PMC4272449 DOI: 10.1016/j.eplepsyres.2014.10.003] [Citation(s) in RCA: 79] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2014] [Revised: 09/16/2014] [Accepted: 10/01/2014] [Indexed: 10/24/2022]
Abstract
The most commonly reported precipitating factor for seizures is stress. However, the underlying mechanisms whereby stress triggers seizures are not yet fully understood. Here we demonstrate a potential mechanism underlying changes in neuronal excitability in the hippocampus following chronic stress, involving a shift in the reversal potential for GABA (EGABA) associated with a dephosphorylation of the potassium chloride co-transporter, KCC2. Mice subjected to chronic restraint stress (30min/day for 14 consecutive days) exhibit an increase in serum corticosterone levels which is associated with increased susceptibility to seizures induced with kainic acid (20mg/kg). Following chronic stress, but not acute stress, we observe a dephosphorylation of KCC2 residue S940, which regulates KCC2 cell surface expression and function, in the hippocampus. To determine the impact of alterations in KCC2 expression following chronic stress, we performed gramicidin perforated patch recordings to measure changes in EGABA and neuronal excitability of principal hippocampal neurons. We observe a depolarizing shift in EGABA in hippocampal CA1 pyramidal neurons after chronic stress. In addition, there is an increase in the intrinsic excitability of CA1 pyramidal neurons, evident by a shift in the input-output curve which could be reversed with the NKCC1 inhibitor, bumetanide. These data uncover a potential mechanism involving chronic stress-induced plasticity in chloride homeostasis which may contribute to stress-induced seizure susceptibility.
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Affiliation(s)
- Georgina MacKenzie
- Department of Neuroscience, Tufts University School of Medicine, Boston, MA, USA
| | - Jamie Maguire
- Department of Neuroscience, Tufts University School of Medicine, Boston, MA, USA.
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158
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Dzhala V, Staley KJ. Acute and chronic efficacy of bumetanide in an in vitro model of posttraumatic epileptogenesis. CNS Neurosci Ther 2014; 21:173-80. [PMID: 25495911 DOI: 10.1111/cns.12369] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2014] [Revised: 11/04/2014] [Accepted: 11/05/2014] [Indexed: 12/30/2022] Open
Abstract
BACKGROUND Seizures triggered by acute injuries to the developing brain respond poorly to first-line medications that target the inhibitory chloride-permeable GABAA receptor. Neuronal injury is associated with profound increases in cytoplasmic chloride ([Cl(-)]i) resulting in depolarizing GABA signaling, higher seizure propensity and limited efficacy of GABAergic anticonvulsants. The Na(+)-K(+)-2Cl(-) (NKCC1) cotransporter blocker bumetanide reduces [Cl(-)]i and causes more negative GABA equilibrium potential in injured neurons. We therefore tested both the acute and chronic efficacy of bumetanide on early posttraumatic ictal-like epileptiform discharges and epileptogenesis. METHODS Acute hippocampal slices were used as a model of severe traumatic brain injury and posttraumatic epileptogenesis. Hippocampal slices were then incubated for 3 weeks. After a 1-week latent period, slice cultures developed chronic spontaneous ictal-like discharges. The anticonvulsant and anti-epileptogenic efficacy of bumetanide, phenobarbital, and the combination of these drugs was studied. RESULTS Bumetanide reduced the frequency and power of early posttraumatic ictal-like discharges in vitro and enhanced the anticonvulsant efficacy of phenobarbital. Continuous 2-3 weeks administration of bumetanide as well as phenobarbital in combination with bumetanide failed to prevent posttraumatic ictal-like discharges and epileptogenesis. CONCLUSIONS Our data demonstrate a persistent contribution of NKCC1 cotransport in posttraumatic ictal-like activity, presumably as a consequence of chronic alterations in neuronal chloride homeostasis and GABA-mediated inhibition. New strategies for more effective reduction in posttraumatic and seizure-induced [Cl(-)]i accumulation could provide the basis for effective treatments for posttraumatic epileptogenesis and the resultant seizures.
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Affiliation(s)
- Volodymyr Dzhala
- Neurology Department, Massachusetts General Hospital, Boston, MA, USA
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159
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Dai S, Ma Z. BDNF-trkB-KCC2-GABA pathway may be related to chronic stress-induced hyperalgesia at both the spinal and supraspinal level. Med Hypotheses 2014; 83:772-4. [PMID: 25454160 DOI: 10.1016/j.mehy.2014.10.008] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2014] [Revised: 09/01/2014] [Accepted: 10/10/2014] [Indexed: 01/15/2023]
Abstract
Chronic stresses can induce physiological and psychological changes and result in stress-related neuropsychiatry, sometimes they may also contribute to hypersensitivity to pain known as stress-induced hyperalgesia (SIH). Recently it was found that GABAergic disinhibition is closely related to morphine and chronic inflammation pain induced hyperalgesia in the PAG (periaqueductal gray)-RVM (rostral ventromedial medulla) -spinal descending facilitatory system, the changes of potassium-chloride co-transporter 2 (KCC2) function or expression modulated by brain-derived neurotrophic factor (BDNF) are involved in it. Similarly, chronic stress could induce changes of BDNF, KCC2 and a depolarizing shift in the GABA reversal potential (EGABA). Moreover, the descending facilitatory system has been suggested to be related with SIH, but whether it modulates SIH through disinhibition by the downregulation of KCC2 expression and/or transport function remains unknown. We therefore hypothesized that SIH may be owned to disinhibition caused by the activation of BDNF-trkB-KCC2-GABA pathway, which would provide a new understanding for SIH.
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Affiliation(s)
- Shuhong Dai
- Department of Anesthesiology, Affiliated Drum Tower Hospital of Medical School of Nanjing University, Nanjing, Jiangsu 210008, China
| | - Zhengliang Ma
- Department of Anesthesiology, Affiliated Drum Tower Hospital of Medical School of Nanjing University, Nanjing, Jiangsu 210008, China.
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160
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Watanabe M, Fukuda A, Nabekura J. The role of GABA in the regulation of GnRH neurons. Front Neurosci 2014; 8:387. [PMID: 25506316 PMCID: PMC4246667 DOI: 10.3389/fnins.2014.00387] [Citation(s) in RCA: 79] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2014] [Accepted: 11/12/2014] [Indexed: 11/13/2022] Open
Abstract
Gonadotropin-releasing hormone (GnRH) neurons form the final common pathway for the central regulation of reproduction. Gamma-amino butyric acid (GABA) has long been implicated as one of the major players in the regulation of GnRH neurons. Although GABA is typically an inhibitory neurotransmitter in the mature adult central nervous system, most mature GnRH neurons show the unusual characteristic of being excited by GABA. While many reports have provided much insight into the contribution of GABA to the activity of GnRH neurons, the precise physiological role of the excitatory action of GABA on GnRH neurons remains elusive. This brief review presents the current knowledge of the role of GABA signaling in GnRH neuronal activity. We also discuss the modulation of GABA signaling by neurotransmitters and neuromodulators and the functional consequence of GABAergic inputs to GnRH neurons in both the physiology and pathology of reproduction.
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Affiliation(s)
- Miho Watanabe
- Department of Neurophysiology, Hamamatsu University School of Medicine Hamamatsu, Japan
| | - Atsuo Fukuda
- Department of Neurophysiology, Hamamatsu University School of Medicine Hamamatsu, Japan
| | - Junichi Nabekura
- Department of Developmental Physiology, National Institute for Physiological Sciences Okazaki, Japan ; Core Research for Evolutionary Science and Technology, Japan Science and Technology Corporation Saitama, Japan ; Department of Physiological Sciences, The Graduate School for Advanced Study Hayama, Japan
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161
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Kaila K, Price TJ, Payne JA, Puskarjov M, Voipio J. Cation-chloride cotransporters in neuronal development, plasticity and disease. Nat Rev Neurosci 2014; 15:637-54. [PMID: 25234263 DOI: 10.1038/nrn3819] [Citation(s) in RCA: 504] [Impact Index Per Article: 50.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Electrical activity in neurons requires a seamless functional coupling between plasmalemmal ion channels and ion transporters. Although ion channels have been studied intensively for several decades, research on ion transporters is in its infancy. In recent years, it has become evident that one family of ion transporters, cation-chloride cotransporters (CCCs), and in particular K(+)-Cl(-) cotransporter 2 (KCC2), have seminal roles in shaping GABAergic signalling and neuronal connectivity. Studying the functions of these transporters may lead to major paradigm shifts in our understanding of the mechanisms underlying brain development and plasticity in health and disease.
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Affiliation(s)
- Kai Kaila
- 1] Department of Biosciences, University of Helsinki, 00014 Helsinki, Finland. [2] Neuroscience Center, University of Helsinki, 00014 Helsinki, Finland
| | - Theodore J Price
- University of Texas at Dallas, School of Behavior and Brain Sciences, Dallas, Texas 75093, USA
| | - John A Payne
- Department of Physiology and Membrane Biology, School of Medicine, University of California, Davis, California 95616, USA
| | - Martin Puskarjov
- 1] Department of Biosciences, University of Helsinki, 00014 Helsinki, Finland. [2] Neuroscience Center, University of Helsinki, 00014 Helsinki, Finland
| | - Juha Voipio
- Department of Biosciences, University of Helsinki, 00014 Helsinki, Finland
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162
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Di Angelantonio S, Murana E, Cocco S, Scala F, Bertollini C, Molinari MG, Lauro C, Bregestovski P, Limatola C, Ragozzino D. A role for intracellular zinc in glioma alteration of neuronal chloride equilibrium. Cell Death Dis 2014; 5:e1501. [PMID: 25356870 PMCID: PMC4237258 DOI: 10.1038/cddis.2014.437] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2014] [Revised: 09/04/2014] [Accepted: 09/09/2014] [Indexed: 11/16/2022]
Abstract
Glioma patients commonly suffer from epileptic seizures. However, the mechanisms of glioma-associated epilepsy are far to be completely understood. Using glioma-neurons co-cultures, we found that tumor cells are able to deeply influence neuronal chloride homeostasis, by depolarizing the reversal potential of γ-aminobutyric acid (GABA)-evoked currents (EGABA). EGABA depolarizing shift is due to zinc-dependent reduction of neuronal KCC2 activity and requires glutamate release from glioma cells. Consistently, intracellular zinc loading rapidly depolarizes EGABA in mouse hippocampal neurons, through the Src/Trk pathway and this effect is promptly reverted upon zinc chelation. This study provides a possible molecular mechanism linking glioma invasion to excitation/inhibition imbalance and epileptic seizures, through the zinc-mediated disruption of neuronal chloride homeostasis.
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Affiliation(s)
- S Di Angelantonio
- Istituto Pasteur-Fondazione Cenci Bolognetti, Department of Physiology and Pharmacology, Sapienza University of Rome, Piazzale Aldo Piazzale Aldo Moro 5, Roma 00185, Italy
- Center for Life Nano Science@Sapienza, Istituto Italiano di Tecnologia, Viale Regina Elena 291, Roma 00161, Italy
| | - E Murana
- Istituto Pasteur-Fondazione Cenci Bolognetti, Department of Physiology and Pharmacology, Sapienza University of Rome, Piazzale Aldo Piazzale Aldo Moro 5, Roma 00185, Italy
| | - S Cocco
- Istituto Pasteur-Fondazione Cenci Bolognetti, Department of Physiology and Pharmacology, Sapienza University of Rome, Piazzale Aldo Piazzale Aldo Moro 5, Roma 00185, Italy
| | - F Scala
- Istituto Pasteur-Fondazione Cenci Bolognetti, Department of Physiology and Pharmacology, Sapienza University of Rome, Piazzale Aldo Piazzale Aldo Moro 5, Roma 00185, Italy
| | - C Bertollini
- Istituto Pasteur-Fondazione Cenci Bolognetti, Department of Physiology and Pharmacology, Sapienza University of Rome, Piazzale Aldo Piazzale Aldo Moro 5, Roma 00185, Italy
| | - M G Molinari
- Istituto Pasteur-Fondazione Cenci Bolognetti, Department of Physiology and Pharmacology, Sapienza University of Rome, Piazzale Aldo Piazzale Aldo Moro 5, Roma 00185, Italy
| | - C Lauro
- Istituto Pasteur-Fondazione Cenci Bolognetti, Department of Physiology and Pharmacology, Sapienza University of Rome, Piazzale Aldo Piazzale Aldo Moro 5, Roma 00185, Italy
| | - P Bregestovski
- INSERM URM 1106, Aix-Marseille University, Brain Dynamics Institute, Marseille, France
| | - C Limatola
- Istituto Pasteur-Fondazione Cenci Bolognetti, Department of Physiology and Pharmacology, Sapienza University of Rome, Piazzale Aldo Piazzale Aldo Moro 5, Roma 00185, Italy
- IRCCS Neuromed, Via Atinese, Pozzilli, Italy
| | - D Ragozzino
- Istituto Pasteur-Fondazione Cenci Bolognetti, Department of Physiology and Pharmacology, Sapienza University of Rome, Piazzale Aldo Piazzale Aldo Moro 5, Roma 00185, Italy
- IRCCS Neuromed, Via Atinese, Pozzilli, Italy
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163
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Drexel M, Puhakka N, Kirchmair E, Hörtnagl H, Pitkänen A, Sperk G. Expression of GABA receptor subunits in the hippocampus and thalamus after experimental traumatic brain injury. Neuropharmacology 2014; 88:122-33. [PMID: 25229716 PMCID: PMC4239297 DOI: 10.1016/j.neuropharm.2014.08.023] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2014] [Revised: 08/26/2014] [Accepted: 08/28/2014] [Indexed: 12/12/2022]
Abstract
Traumatic brain injury is a major cause of death and disability worldwide and often associated with post-traumatic epilepsy. We recently demonstrated that TBI induces acquired GABAA receptors channelopathy that associates with hyperexcitability in granule cell layer (GCL). We now assessed the expression of GABAA and GABAB receptor subunit mRNAs between 6 h and 6 months post-TBI in the hippocampus and thalamus. The expression of major GABAA receptor subunit mRNAs (α1, α2, α5, β2, β3, γ2 and δ) was, often bilaterally, down-regulated in the GCL and in the CA3 pyramidal cells. Instead, expression of α4 (GCL, CA3, CA1), α5 (CA1) and γ2 (GCL, CA3, CA1) mRNA was up-regulated after 10 d and/or 4 months. Many of these changes were reversible. In the thalamus, we found decreases in α1, α4, β2, γ2 and δ mRNAs in the laterodorsal thalamus and in the area combining the posterior thalamic nuclear group, ventroposterolateral and ventroposteromedial complex at 6 h to 4 months post-TBI. Unlike in the hippocampus, thalamic subunit down-regulations were irreversible and limited to the ipsilateral side. However, contralaterally there was up-regulation of the subunits δ and α4 6 h and 4 months after TBI, respectively. PCR array analysis suggested a mild long-lasting GABAA receptor channelopathy in the GCL and thalamus after TBI. Whereas TBI induces transient changes in the expression of GABAA receptor subunits in the hippocampus (presumably representing compensatory mechanisms), alterations of GABAA receptor subunit mRNAs in the thalamus are long-lasting and related to degeneration of receptor-containing neurons in thalamo-cortical relay nuclei. This article is part of the Special Issue entitled ‘GABAergic Signaling in Health and Disease’. GABAA receptor subunits are permanently lost in thalamic nuclei on the side of TBI. They are only transiently decreased in hippocampal subfields bilaterally. Subunit α4 is up-regulated in the thalamus and hippocampus contralateral to TBI. Efficacy of neurosteroids in preventing secondary epilepsy after TBI is suggested.
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Affiliation(s)
- Meinrad Drexel
- Department of Pharmacology, Innsbruck Medical University, 6020 Innsbruck, Austria.
| | - Noora Puhakka
- Department of Neurobiology, A. I. Virtanen Institute for Molecular Science, University of Eastern Finland, PO Box 1627, FI-70211 Kuopio, Finland
| | - Elke Kirchmair
- Department of Pharmacology, Innsbruck Medical University, 6020 Innsbruck, Austria
| | - Heide Hörtnagl
- Department of Pharmacology, Innsbruck Medical University, 6020 Innsbruck, Austria
| | - Asla Pitkänen
- Department of Neurobiology, A. I. Virtanen Institute for Molecular Science, University of Eastern Finland, PO Box 1627, FI-70211 Kuopio, Finland; Department of Neurology, Kuopio University Hospital, PO Box 1777, FI-70211 Kuopio, Finland
| | - Günther Sperk
- Department of Pharmacology, Innsbruck Medical University, 6020 Innsbruck, Austria
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164
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MacKenzie G, Maguire J. The role of ovarian hormone-derived neurosteroids on the regulation of GABAA receptors in affective disorders. Psychopharmacology (Berl) 2014; 231:3333-42. [PMID: 24402140 PMCID: PMC4090295 DOI: 10.1007/s00213-013-3423-z] [Citation(s) in RCA: 63] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/06/2013] [Accepted: 12/17/2013] [Indexed: 11/27/2022]
Abstract
RATIONALE Neuroactive derivatives of steroid hormones, neurosteroids, can act on GABAA receptors (GABAARs) to potentiate the effects of GABA on these receptors. Neurosteroids become elevated to physiologically relevant levels under conditions characterized by increased steroid hormones. There is considerable evidence for plasticity of GABAARs associated with altered levels of neurosteroids which may counteract the fluctuations in the levels of these allosteric modulators. OBJECTIVES The objective of this review is to summarize the current literature on GABAAR plasticity under conditions characterized by alterations in neurosteroid levels, such as over the estrous cycle, during puberty, and throughout pregnancy and the postpartum period. RESULTS The expression of specific GABAAR subunits is altered over the estrous cycle, at puberty, and throughout pregnancy and the postpartum period. Inability to regulate δ subunit-containing GABAARs throughout pregnancy and the postpartum period is associated with depression-like behavior restricted to the postpartum period. CONCLUSIONS GABAAR plasticity associated with alterations in neurosteroid levels represents a homeostatic compensatory mechanism to maintain an ideal level of inhibition to offset the potentiating effects of neurosteroids on GABAergic inhibition. Failure to properly regulate GABAARs under conditions of altered neurosteroid levels may increase vulnerability to mood disorders, such as premenstrual syndrome (PMS), premenstrual dysphoric disorder (PMDD), and postpartum depression.
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Affiliation(s)
- Georgina MacKenzie
- Tufts University School of Medicine, Department of Neuroscience, Boston, MA 02111
| | - Jamie Maguire
- Tufts University School of Medicine, Department of Neuroscience, Boston, MA 02111
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165
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Côté MP, Gandhi S, Zambrotta M, Houlé JD. Exercise modulates chloride homeostasis after spinal cord injury. J Neurosci 2014; 34:8976-87. [PMID: 24990918 PMCID: PMC6608257 DOI: 10.1523/jneurosci.0678-14.2014] [Citation(s) in RCA: 77] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2014] [Revised: 05/20/2014] [Accepted: 05/24/2014] [Indexed: 01/09/2023] Open
Abstract
Activity-based therapies are routinely integrated in spinal cord injury (SCI) rehabilitation programs because they result in a reduction of hyperreflexia and spasticity. However, the mechanisms by which exercise regulates activity in spinal pathways to reduce spasticity and improve functional recovery are poorly understood. Persisting alterations in the action of GABA on postsynaptic targets is a signature of CNS injuries, including SCI. The action of GABA depends on the intracellular chloride concentration, which is determined largely by the expression of two cation-chloride cotransporters (CCCs), KCC2 and NKCC1, which serve as chloride exporters and importers, respectively. We hypothesized that the reduction in hyperreflexia with exercise after SCI relies on a return to chloride homeostasis. Sprague Dawley rats received a spinal cord transection at T12 and were assigned to SCI-7d, SCI-14d, SCI-14d+exercise, SCI-28d, SCI-28d+exercise, or SCI-56d groups. During a terminal experiment, H-reflexes were recorded from interosseus muscles after stimulation of the tibial nerve and the low-frequency-dependent depression (FDD) was assessed. We provide evidence that exercise returns spinal excitability and levels of KCC2 and NKCC1 toward normal levels in the lumbar spinal cord. Acutely altering chloride extrusion using the KCC2 blocker DIOA masked the effect of exercise on FDD, whereas blocking NKCC1 with bumetanide returned FDD toward intact levels after SCI. Our results indicate that exercise contributes to reflex recovery and restoration of endogenous inhibition through a return to chloride homeostasis after SCI. This lends support for CCCs as part of a pathway that could be manipulated to improve functional recovery when combined with rehabilitation programs.
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Affiliation(s)
- Marie-Pascale Côté
- Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, Pennsylvania 19129
| | - Sapan Gandhi
- Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, Pennsylvania 19129
| | - Marina Zambrotta
- Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, Pennsylvania 19129
| | - John D Houlé
- Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, Pennsylvania 19129
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166
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Postsynaptic activity reverses the sign of the acetylcholine-induced long-term plasticity of GABAA inhibition. Proc Natl Acad Sci U S A 2014; 111:E2741-50. [PMID: 24938789 DOI: 10.1073/pnas.1321777111] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Acetylcholine (ACh) regulates forms of plasticity that control cognitive functions but the underlying mechanisms remain largely unknown. ACh controls the intrinsic excitability, as well as the synaptic excitation and inhibition of CA1 hippocampal pyramidal cells (PCs), cells known to participate in circuits involved in cognition and spatial navigation. However, how ACh regulates inhibition in function of postsynaptic activity has not been well studied. Here we show that in rat PCs, a brief pulse of ACh or a brief stimulation of cholinergic septal fibers combined with repeated depolarization induces strong long-term enhancement of GABAA inhibition (GABAA-LTP). Indeed, this enhanced inhibition is due to the increased activation of α5βγ2 subunit-containing GABAA receptors by the GABA released. GABAA-LTP requires the activation of M1-muscarinic receptors and an increase in cytosolic Ca(2+). In the absence of PC depolarization ACh triggered a presynaptic depolarization-induced suppression of inhibition (DSI), revealing that postsynaptic activity gates the effects of ACh from presynaptic DSI to postsynaptic LTP. These results provide key insights into mechanisms potentially linked with cognitive functions, spatial navigation, and the homeostatic control of abnormal hyperexcitable states.
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167
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Yassin L, Radtke-Schuller S, Asraf H, Grothe B, Hershfinkel M, Forsythe ID, Kopp-Scheinpflug C. Nitric oxide signaling modulates synaptic inhibition in the superior paraolivary nucleus (SPN) via cGMP-dependent suppression of KCC2. Front Neural Circuits 2014; 8:65. [PMID: 24987336 PMCID: PMC4060731 DOI: 10.3389/fncir.2014.00065] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2014] [Accepted: 05/28/2014] [Indexed: 11/13/2022] Open
Abstract
Glycinergic inhibition plays a central role in the auditory brainstem circuitries involved in sound localization and in the encoding of temporal action potential firing patterns. Modulation of this inhibition has the potential to fine-tune information processing in these networks. Here we show that nitric oxide (NO) signaling in the auditory brainstem (where activity-dependent generation of NO is documented) modulates the strength of inhibition by changing the chloride equilibrium potential. Recent evidence demonstrates that large inhibitory postsynaptic currents (IPSCs) in neurons of the superior paraolivary nucleus (SPN) are enhanced by a very low intracellular chloride concentration, generated by the neuronal potassium chloride co-transporter (KCC2) expressed in the postsynaptic neurons. Our data show that modulation by NO caused a 15 mV depolarizing shift of the IPSC reversal potential, reducing the strength of inhibition in SPN neurons, without changing the threshold for action potential firing. Regulating inhibitory strength, through cGMP-dependent changes in the efficacy of KCC2 in the target neuron provides a postsynaptic mechanism for rapidly controlling the inhibitory drive, without altering the timing or pattern of the afferent spike train. Therefore, this NO-mediated suppression of KCC2 can modulate inhibition in one target nucleus (SPN), without influencing inhibitory strength of other target nuclei (MSO, LSO) even though they are each receiving collaterals from the same afferent nucleus (a projection from the medial nucleus of the trapezoid body, MNTB).
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Affiliation(s)
- Lina Yassin
- Division of Neurobiology, Department Biology II, Ludwig-Maximilians-University MunichPlanegg-Martinsried, Germany
| | - Susanne Radtke-Schuller
- Division of Neurobiology, Department Biology II, Ludwig-Maximilians-University MunichPlanegg-Martinsried, Germany
| | - Hila Asraf
- Department of Physiology and Cell Biology, Faculty of Health Sciences, Ben-Gurion University of the NegevBeer-Sheva, Israel
| | - Benedikt Grothe
- Division of Neurobiology, Department Biology II, Ludwig-Maximilians-University MunichPlanegg-Martinsried, Germany
| | - Michal Hershfinkel
- Department of Physiology and Cell Biology, Faculty of Health Sciences, Ben-Gurion University of the NegevBeer-Sheva, Israel
| | - Ian D. Forsythe
- Department of Cell Physiology and Pharmacology, University of LeicesterLeicester, UK
| | - Cornelia Kopp-Scheinpflug
- Division of Neurobiology, Department Biology II, Ludwig-Maximilians-University MunichPlanegg-Martinsried, Germany
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168
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Kaila K, Ruusuvuori E, Seja P, Voipio J, Puskarjov M. GABA actions and ionic plasticity in epilepsy. Curr Opin Neurobiol 2014; 26:34-41. [PMID: 24650502 DOI: 10.1016/j.conb.2013.11.004] [Citation(s) in RCA: 167] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2013] [Revised: 10/23/2013] [Accepted: 11/06/2013] [Indexed: 11/18/2022]
Abstract
Concepts of epilepsy, based on a simple change in neuronal excitation/inhibition balance, have subsided in face of recent insights into the large diversity and context-dependence of signaling mechanisms at the molecular, cellular and neuronal network level. GABAergic transmission exerts both seizure-suppressing and seizure-promoting actions. These two roles are prone to short-term and long-term alterations, evident both during epileptogenesis and during individual epileptiform events. The driving force of GABAergic currents is controlled by ion-regulatory molecules such as the neuronal K-Cl cotransporter KCC2 and cytosolic carbonic anhydrases. Accumulating evidence suggests that neuronal ion regulation is highly plastic, thereby contributing to the multiple roles ascribed to GABAergic signaling during epileptogenesis and epilepsy.
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Affiliation(s)
- Kai Kaila
- Department of Biosciences, University of Helsinki, FI-00014 Helsinki, Finland; Neuroscience Center, University of Helsinki, FI-00014 Helsinki, Finland.
| | - Eva Ruusuvuori
- Department of Biosciences, University of Helsinki, FI-00014 Helsinki, Finland; Neuroscience Center, University of Helsinki, FI-00014 Helsinki, Finland
| | - Patricia Seja
- Department of Biosciences, University of Helsinki, FI-00014 Helsinki, Finland; Neuroscience Center, University of Helsinki, FI-00014 Helsinki, Finland
| | - Juha Voipio
- Department of Biosciences, University of Helsinki, FI-00014 Helsinki, Finland
| | - Martin Puskarjov
- Department of Biosciences, University of Helsinki, FI-00014 Helsinki, Finland; Neuroscience Center, University of Helsinki, FI-00014 Helsinki, Finland
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169
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Nikulina EM, Johnston CE, Wang J, Hammer RP. Neurotrophins in the ventral tegmental area: Role in social stress, mood disorders and drug abuse. Neuroscience 2014; 282:122-38. [PMID: 24875178 DOI: 10.1016/j.neuroscience.2014.05.028] [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: 01/30/2014] [Revised: 05/04/2014] [Accepted: 05/11/2014] [Indexed: 01/19/2023]
Abstract
This review discusses the impact of neurotrophins and other trophic factors, including fibroblast growth factor and glial cell line-derived neurotrophic factor, on mood disorders, weight regulation and drug abuse, with an emphasis on stress- and drug-induced changes in the ventral tegmental area (VTA). Neurotrophins, comprising nerve growth factor, brain-derived neurotrophic factor (BDNF), and neurotrophins 3 and 4/5 play important roles in neuronal plasticity and the development of different psychopathologies. In the VTA, most research has focused on the role of BDNF, because other neurotrophins are not found there in significant quantities. BDNF originating in the VTA provides trophic support to dopamine neurons. The diverse intracellular signaling pathways activated by BDNF may underlie precise physiological functions specific to the VTA. In general, VTA BDNF expression increases after psychostimulant exposures, and enhanced BDNF level in the VTA facilitates psychostimulant effects. The impact of VTA BDNF on the behavioral effects of psychostimulants relies primarily on its action within the mesocorticolimbic circuit. In the case of opiates, VTA BDNF expression and effects seem to be dependent on whether an animal is drug-naïve or has a history of drug use, only the latter of which is related to dopamine mechanisms. Social defeat stress that is continuous in mice or intermittent in rats increases VTA BDNF expression, and is associated with depressive and social avoidance behaviors. Intermittent social defeat stress induces persistent VTA BDNF expression that triggers psychostimulant cross-sensitization. Understanding the cellular and molecular substrates of neurotrophin effects may lead to novel therapeutic approaches for the prevention and treatment of substance use and mood disorders.
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Affiliation(s)
- E M Nikulina
- Department of Basic Medical Sciences, University of Arizona College of Medicine, Phoenix, AZ, USA.
| | - C E Johnston
- Department of Basic Medical Sciences, University of Arizona College of Medicine, Phoenix, AZ, USA; Interdisciplinary Neuroscience Program, Arizona State University, Tempe, AZ, USA
| | - J Wang
- Interdisciplinary Neuroscience Program, Arizona State University, Tempe, AZ, USA
| | - R P Hammer
- Department of Basic Medical Sciences, University of Arizona College of Medicine, Phoenix, AZ, USA; Interdisciplinary Neuroscience Program, Arizona State University, Tempe, AZ, USA; Department of Pharmacology and Department of Psychiatry, University of Arizona College of Medicine, Tucson, AZ, USA
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170
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Akman O, Moshé SL, Galanopoulou AS. Sex-specific consequences of early life seizures. Neurobiol Dis 2014; 72 Pt B:153-66. [PMID: 24874547 DOI: 10.1016/j.nbd.2014.05.021] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2014] [Revised: 05/07/2014] [Accepted: 05/17/2014] [Indexed: 12/29/2022] Open
Abstract
Seizures are very common in the early periods of life and are often associated with poor neurologic outcome in humans. Animal studies have provided evidence that early life seizures may disrupt neuronal differentiation and connectivity, signaling pathways, and the function of various neuronal networks. There is growing experimental evidence that many signaling pathways, like GABAA receptor signaling, the cellular physiology and differentiation, or the functional maturation of certain brain regions, including those involved in seizure control, mature differently in males and females. However, most experimental studies of early life seizures have not directly investigated the importance of sex on the consequences of early life seizures. The sexual dimorphism of the developing brain raises the question that early seizures could have distinct effects in immature females and males that are subjected to seizures. We will first discuss the evidence for sex-specific features of the developing brain that could be involved in modifying the susceptibility and consequences of early life seizures. We will then review how sex-related biological factors could modify the age-specific consequences of induced seizures in the immature animals. These include signaling pathways (e.g., GABAA receptors), steroid hormones, growth factors. Overall, there are very few studies that have specifically addressed seizure outcomes in developing animals as a function of sex. The available literature indicates that a variety of outcomes (histopathological, behavioral, molecular, epileptogenesis) may be affected in a sex-, age-, region-specific manner after seizures during development. Obtaining a better understanding for the gender-related mechanisms underlying epileptogenesis and seizure comorbidities will be necessary to develop better gender and age appropriate therapies.
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Affiliation(s)
- Ozlem Akman
- Department of Physiology, Faculty of Medicine, Istanbul Bilim University, 34394 Istanbul, Turkey.
| | - Solomon L Moshé
- Saul R. Korey Department of Neurology, Laboratory of Developmental Epilepsy, Montefiore Epilepsy Management Center, Albert Einstein College of Medicine and Montefiore Medical Center, Bronx, NY, 10461, USA; Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine and Montefiore Medical Center, Bronx, NY, 10461, USA; Department of Pediatrics, Albert Einstein College of Medicine and Montefiore Medical Center, Bronx, NY, 10461, USA
| | - Aristea S Galanopoulou
- Saul R. Korey Department of Neurology, Laboratory of Developmental Epilepsy, Montefiore Epilepsy Management Center, Albert Einstein College of Medicine and Montefiore Medical Center, Bronx, NY, 10461, USA; Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine and Montefiore Medical Center, Bronx, NY, 10461, USA
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171
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Bergeron MJ, Castonguay A, De Koninck Y. [KCC2: a new therapeutical target for the treatment of neurological diseases]. Med Sci (Paris) 2014; 30:514-7. [PMID: 24939537 DOI: 10.1051/medsci/20143005013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2023] Open
Affiliation(s)
- Marc J Bergeron
- Centre de recherche de l'Institut universitaire en santé mentale de Québec, 2601, de la Canardière, G1J 2G3 Québec, Canada
| | - Annie Castonguay
- Centre de recherche de l'Institut universitaire en santé mentale de Québec, 2601, de la Canardière, G1J 2G3 Québec, Canada
| | - Yves De Koninck
- Centre de recherche de l'Institut universitaire en santé mentale de Québec, 2601, de la Canardière, G1J 2G3 Québec, Canada
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172
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Richner M, Ulrichsen M, Elmegaard SL, Dieu R, Pallesen LT, Vaegter CB. Peripheral nerve injury modulates neurotrophin signaling in the peripheral and central nervous system. Mol Neurobiol 2014; 50:945-70. [PMID: 24752592 DOI: 10.1007/s12035-014-8706-9] [Citation(s) in RCA: 108] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2013] [Accepted: 04/01/2014] [Indexed: 12/21/2022]
Abstract
Peripheral nerve injury disrupts the normal functions of sensory and motor neurons by damaging the integrity of axons and Schwann cells. In contrast to the central nervous system, the peripheral nervous system possesses a considerable capacity for regrowth, but regeneration is far from complete and functional recovery rarely returns to pre-injury levels. During development, the peripheral nervous system strongly depends upon trophic stimulation for neuronal differentiation, growth and maturation. The perhaps most important group of trophic substances in this context is the neurotrophins (NGF, BDNF, NT-3 and NT-4/5), which signal in a complex spatial and timely manner via the two structurally unrelated p75(NTR) and tropomyosin receptor kinase (TrkA, Trk-B and Trk-C) receptors. Damage to the adult peripheral nerves induces cellular mechanisms resembling those active during development, resulting in a rapid and robust increase in the synthesis of neurotrophins in neurons and Schwann cells, guiding and supporting regeneration. Furthermore, the injury induces neurotrophin-mediated changes in the dorsal root ganglia and in the spinal cord, which affect the modulation of afferent sensory signaling and eventually may contribute to the development of neuropathic pain. The focus of this review is on the expression patterns of neurotrophins and their receptors in neurons and glial cells of the peripheral nervous system and the spinal cord. Furthermore, injury-induced changes of expression patterns and the functional consequences in relation to axonal growth and remyelination as well as to neuropathic pain development will be reviewed.
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Affiliation(s)
- Mette Richner
- Danish Research Institute of Translational Neuroscience DANDRITE, Nordic EMBL Partnership, and Lundbeck Foundation Research Center MIND, Department of Biomedicine, Aarhus University, Ole Worms Allé 3, 8000, Aarhus C, Denmark
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DiNuzzo M, Mangia S, Maraviglia B, Giove F. Physiological bases of the K+ and the glutamate/GABA hypotheses of epilepsy. Epilepsy Res 2014; 108:995-1012. [PMID: 24818957 DOI: 10.1016/j.eplepsyres.2014.04.001] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2014] [Revised: 03/20/2014] [Accepted: 04/01/2014] [Indexed: 01/19/2023]
Abstract
Epilepsy is a heterogeneous family of neurological disorders that manifest as seizures, i.e. the hypersynchronous activity of large population of neurons. About 30% of epileptic patients do not respond to currently available antiepileptic drugs. Decades of intense research have elucidated the involvement of a number of possible signaling pathways, however, at present we do not have a fundamental understanding of epileptogenesis. In this paper, we review the literature on epilepsy under a wide-angle perspective, a mandatory choice that responds to the recurrent and unanswered question about what is epiphenomenal and what is causal to the disease. While focusing on the involvement of K+ and glutamate/GABA in determining neuronal hyperexcitability, emphasis is given to astrocytic contribution to epileptogenesis, and especially to loss-of-function of astrocytic glutamine synthetase following reactive astrogliosis, a hallmark of epileptic syndromes. We finally introduce the potential involvement of abnormal glycogen synthesis induced by excess glutamate in increasing susceptibility to seizures.
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Affiliation(s)
- Mauro DiNuzzo
- MARBILab, Museo storico della fisica e Centro di studi e ricerche "Enrico Fermi", Rome, Italy.
| | - Silvia Mangia
- Center for Magnetic Resonance Research, Department of Radiology, University of Minnesota, Minneapolis, MN, USA
| | - Bruno Maraviglia
- Dipartimento di Fisica, Sapienza Università di Roma, Rome, Italy; Fondazione Santa Lucia IRCCS, Rome, Italy
| | - Federico Giove
- MARBILab, Museo storico della fisica e Centro di studi e ricerche "Enrico Fermi", Rome, Italy; Dipartimento di Fisica, Sapienza Università di Roma, Rome, Italy
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174
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Gao XP, Liu Q, Nair B, Wong-Riley MTT. Reduced levels of brain-derived neurotrophic factor contribute to synaptic imbalance during the critical period of respiratory development in rats. Eur J Neurosci 2014; 40:2183-95. [PMID: 24666389 DOI: 10.1111/ejn.12568] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2013] [Revised: 02/15/2014] [Accepted: 02/18/2014] [Indexed: 02/06/2023]
Abstract
Previously, our electrophysiological studies revealed a transient imbalance between suppressed excitation and enhanced inhibition in hypoglossal motoneurons of rats on postnatal days (P) 12-13, a critical period when abrupt neurochemical, metabolic, ventilatory and physiological changes occur in the respiratory system. The mechanism underlying the imbalance is poorly understood. We hypothesised that the imbalance was contributed by a reduced expression of brain-derived neurotrophic factor (BDNF), which normally enhances excitation and suppresses inhibition. We also hypothesised that exogenous BDNF would partially reverse this synaptic imbalance. Immunohistochemistry/single-neuron optical densitometry, real-time quantitative PCR (RT-qPCR) and whole-cell patch-clamp recordings were done on hypoglossal motoneurons in brainstem slices of rats during the first three postnatal weeks. Our results indicated that: (1) the levels of BDNF and its high-affinity tyrosine receptor kinase B (TrkB) receptor mRNAs and proteins were relatively high during the first 1-1.5 postnatal weeks, but dropped precipitously at P12-13 before rising again afterwards; (2) exogenous BDNF significantly increased the normally lowered frequency of spontaneous excitatory postsynaptic currents but decreased the normally heightened amplitude and frequency of spontaneous inhibitory postsynaptic currents (sIPSCs) during the critical period; (3) exogenous BDNF also decreased the normally heightened frequency of miniature IPSCs at P12-13; and (4) the effect of exogenous BDNF was partially blocked by K252a, a TrkB receptor antagonist. Thus, our results are consistent with our hypothesis that BDNF and TrkB play an important role in the synaptic imbalance during the critical period. This may have significant implications for the mechanism underlying sudden infant death syndrome.
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Affiliation(s)
- Xiu-Ping Gao
- Department of Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, 8701 Watertown Plank Rd, Milwaukee, WI, 53226, USA
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175
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Ziemlińska E, Kügler S, Schachner M, Wewiór I, Czarkowska-Bauch J, Skup M. Overexpression of BDNF increases excitability of the lumbar spinal network and leads to robust early locomotor recovery in completely spinalized rats. PLoS One 2014; 9:e88833. [PMID: 24551172 PMCID: PMC3925164 DOI: 10.1371/journal.pone.0088833] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2013] [Accepted: 01/16/2014] [Indexed: 02/05/2023] Open
Abstract
Strategies to induce recovery from lesions of the spinal cord have not fully resulted in clinical applications. This is a consequence of a number of impediments that axons encounter when trying to regrow beyond the lesion site, and that intraspinal rearrangements are subjected to. In the present study we evaluated (1) the possibility to improve locomotor recovery after complete transection of the spinal cord by means of an adeno-associated (AAV) viral vector expressing the neurotrophin brain-derived neurotrophic factor (BDNF) in lumbar spinal neurons caudal to the lesion site and (2) how the spinal cord transection and BDNF treatment affected neurotransmission in the segments caudal to the lesion site. BDNF overexpression resulted in clear increases in expression levels of molecules involved in glutamatergic (VGluT2) and GABAergic (GABA, GAD65, GAD67) neurotransmission in parallel with a reduction of the potassium-chloride co-transporter (KCC2) which contributes to an inhibitory neurotransmission. BDNF treated animals showed significant improvements in assisted locomotor performance, and performed locomotor movements with body weight support and plantar foot placement on a moving treadmill. These positive effects of BDNF local overexpression were detectable as early as two weeks after spinal cord transection and viral vector application and lasted for at least 7 weeks. Gradually increasing frequencies of clonic movements at the end of the experiment attenuated the quality of treadmill walking. These data indicate that BDNF has the potential to enhance the functionality of isolated lumbar circuits, but also that BDNF levels have to be tightly controlled to prevent hyperexcitability.
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Affiliation(s)
| | - Sebastian Kügler
- Center of Molecular Physiology of the Brain, University of Göttingen, Göttingen, Germany
| | - Melitta Schachner
- Center for Neuroscience, Shantou University Medical College, Shantou, China
| | - Iwona Wewiór
- Nencki Institute of Experimental Biology, Warsaw, Poland
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176
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Medina I, Friedel P, Rivera C, Kahle KT, Kourdougli N, Uvarov P, Pellegrino C. Current view on the functional regulation of the neuronal K(+)-Cl(-) cotransporter KCC2. Front Cell Neurosci 2014; 8:27. [PMID: 24567703 PMCID: PMC3915100 DOI: 10.3389/fncel.2014.00027] [Citation(s) in RCA: 137] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2013] [Accepted: 01/18/2014] [Indexed: 12/22/2022] Open
Abstract
In the mammalian central nervous system (CNS), the inhibitory strength of chloride (Cl(-))-permeable GABAA and glycine receptors (GABAAR and GlyR) depends on the intracellular Cl(-) concentration ([Cl(-)]i). Lowering [Cl(-)]i enhances inhibition, whereas raising [Cl(-)]i facilitates neuronal activity. A neuron's basal level of [Cl(-)]i, as well as its Cl(-) extrusion capacity, is critically dependent on the activity of the electroneutral K(+)-Cl(-) cotransporter KCC2, a member of the SLC12 cation-Cl(-) cotransporter (CCC) family. KCC2 deficiency compromises neuronal migration, formation and the maturation of GABAergic and glutamatergic synaptic connections, and results in network hyperexcitability and seizure activity. Several neurological disorders including multiple epilepsy subtypes, neuropathic pain, and schizophrenia, as well as various insults such as trauma and ischemia, are associated with significant decreases in the Cl(-) extrusion capacity of KCC2 that result in increases of [Cl(-)]i and the subsequent hyperexcitability of neuronal networks. Accordingly, identifying the key upstream molecular mediators governing the functional regulation of KCC2, and modifying these signaling pathways with small molecules, might constitute a novel neurotherapeutic strategy for multiple diseases. Here, we discuss recent advances in the understanding of the mechanisms regulating KCC2 activity, and of the role these mechanisms play in neuronal Cl(-) homeostasis and GABAergic neurotransmission. As KCC2 mediates electroneutral transport, the experimental recording of its activity constitutes an important research challenge; we therefore also, provide an overview of the different methodological approaches utilized to monitor function of KCC2 in both physiological and pathological conditions.
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Affiliation(s)
- Igor Medina
- INSERM, Institut de Neurobiologie de la Méditerranée (INMED)Marseille, France
- Aix-Marseille Université, UMR901Marseille, France
| | - Perrine Friedel
- INSERM, Institut de Neurobiologie de la Méditerranée (INMED)Marseille, France
- Aix-Marseille Université, UMR901Marseille, France
| | - Claudio Rivera
- INSERM, Institut de Neurobiologie de la Méditerranée (INMED)Marseille, France
- Aix-Marseille Université, UMR901Marseille, France
- Neuroscience Center, University of HelsinkiHelsinki, Finland
| | - Kristopher T. Kahle
- Department of Cardiology, Manton Center for Orphan Disease Research, Howard Hughes Medical Institute, Boston Children's HospitalBoston, MA, USA
- Department of Neurosurgery, Massachusetts General Hospital and Harvard Medical SchoolBoston, MA, USA
| | - Nazim Kourdougli
- INSERM, Institut de Neurobiologie de la Méditerranée (INMED)Marseille, France
- Aix-Marseille Université, UMR901Marseille, France
| | - Pavel Uvarov
- Institute of Biomedicine, Anatomy, University of HelsinkiHelsinki, Finland
| | - Christophe Pellegrino
- INSERM, Institut de Neurobiologie de la Méditerranée (INMED)Marseille, France
- Aix-Marseille Université, UMR901Marseille, France
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177
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He XP, Wen R, McNamara JO. Impairment of kindling development in phospholipase Cγ1 heterozygous mice. Epilepsia 2014; 55:456-63. [PMID: 24502564 DOI: 10.1111/epi.12536] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/13/2013] [Indexed: 01/09/2023]
Abstract
OBJECTIVE Elucidating molecular mechanisms underlying limbic epileptogenesis may reveal novel targets for preventive therapy. Studies of TrkB mutant mice led us to hypothesize that signaling through a specific phospholipase (PLC), PLCγ1, promoted development of kindling. METHODS To test this hypothesis, we examined the development of kindling in PLCγ1 heterozygous mice. We also examined the cellular and subcellular location of PLCγ1 in adult wild-type mice. RESULTS The development of kindling was impaired in PLCγ1 heterozygous mice compared to wild-type controls. PLCγ1 immunoreactivity was localized to the soma and dendrites of both excitatory and inhibitory neurons in the hippocampus of adult mice. SIGNIFICANCE This study implicates PLCγ1 signaling as the dominant pathway by which TrkB activation promotes limbic epileptogenesis. Its cellular localization places PLCγ1 in a position to modify the efficacy of both excitatory and inhibitory synaptic transmission. These findings advance PLCγ1 as a novel target for therapies aimed at preventing temporal lobe epilepsy induced by status epilepticus.
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Affiliation(s)
- Xiao Ping He
- Department of Medicine (Neurology), Duke University Medical Center, Durham, North Carolina, U.S.A
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178
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Kang SK, Kadam SD. Pre-Clinical Models of Acquired Neonatal Seizures: Differential Effects of Injury on Function of Chloride Co-Transporters. AUSTIN JOURNAL OF CEREBROVASCULAR DISEASE & STROKE 2014; 1:1026. [PMID: 25590049 PMCID: PMC4290373] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Hypoxic-ischemic encephalopathy [HIE] represents the most common acquired pathology associated with neonatal seizures. HIE-associated neonatal seizures are often difficult to control, due to their refractoriness to traditional anti-seizure agents. Developmentally regulated chloride gradients during early development make the neonatal brain more seizure-susceptible by depolarizing GABAAR-mediated currents, and therefore hindering inhibition by conventional anti-seizure drugs such as phenobarbital [PB] and benzodiazepines. Pharmaco-modulation of chloride co-transporters has become a current field of research in treating refractory neonatal seizures, and the basis of two clinical trials [NCT01434225; NCT00380531]. However, the recent termination of NEMO study [NCT01434225] on bumetanide, an NKCC1 antagonist, suggests that clinical utilization of bumetanide as an adjunct to treat neonatal seizures with PB may not be a viable option. Hence, re-evaluation of bumetanide as an adjunct through pre-clinical studies is warranted. Additionally, the model-specific variability in the efficacy of bumetanide in the pre-clinical models of neonatal seizures highlights the differential consequences of insults used to induce seizures in each pre-clinical model as worth exploration. Injury itself can significantly alter the function of chloride co-transporters, and therefore the efficacy of anti-seizure agents that follow.
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Affiliation(s)
- SK Kang
- Neuroscience Laboratory, Hugo Moser Research Institute, USA
| | - SD Kadam
- Neuroscience Laboratory, Hugo Moser Research Institute, USA
- Department of Neurology, Johns Hopkins University, USA
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179
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Bonin RP, De Koninck Y. Restoring ionotropic inhibition as an analgesic strategy. Neurosci Lett 2013; 557 Pt A:43-51. [PMID: 24080373 DOI: 10.1016/j.neulet.2013.09.047] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2013] [Revised: 09/11/2013] [Accepted: 09/16/2013] [Indexed: 12/31/2022]
Abstract
Neuronal inhibition in nociceptive relays of the spinal cord is essential for the proper processing of nociceptive information. In the spinal cord dorsal horn, the activity of synaptic and extrasynaptic GABAA and glycine receptors generates rapid, Cl(-)-dependent neuronal inhibition. A loss of this ionotropic inhibition, particularly through the collapse of the inhibitory Cl(-)-gradient, is a key mechanism by which pathological pain conditions develop. This review summarizes the roles of ionotropic inhibition in the regulation of nociception, and explores recent evidence that the potentiation of GABAA or glycine receptor activity or the enhancement of inhibitory drive can reverse pathological pain.
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Affiliation(s)
- Robert P Bonin
- Unité de neurosciences cellulaires et moléculaire, Centre de recherche de l'institut universitaire en santé mentale de Québec, Québec, Canada
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180
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Kahle KT, Deeb TZ, Puskarjov M, Silayeva L, Liang B, Kaila K, Moss SJ. Modulation of neuronal activity by phosphorylation of the K-Cl cotransporter KCC2. Trends Neurosci 2013; 36:726-737. [PMID: 24139641 PMCID: PMC4381966 DOI: 10.1016/j.tins.2013.08.006] [Citation(s) in RCA: 154] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2013] [Revised: 08/19/2013] [Accepted: 08/26/2013] [Indexed: 12/29/2022]
Abstract
The K-Cl cotransporter KCC2 establishes the low intraneuronal Cl- levels required for the hyperpolarizing inhibitory postsynaptic potentials mediated by ionotropic γ-aminobutyric acid receptors (GABAARs) and glycine receptors (GlyRs). Decreased KCC2-mediated Cl- extrusion and impaired hyperpolarizing GABAAR- and/or GlyR-mediated currents have been implicated in epilepsy, neuropathic pain, and spasticity. Recent evidence suggests that the intrinsic ion transport rate, cell surface stability, and plasmalemmal trafficking of KCC2 are rapidly and reversibly modulated by the (de)phosphorylation of critical serine, threonine, and tyrosine residues in the C terminus of this protein. Alterations in KCC2 phosphorylation have been associated with impaired KCC2 function in several neurological diseases. Targeting KCC2 phosphorylation directly or indirectly via upstream regulatory kinases might be a novel strategy to modulate GABA- and/or glycinergic signaling for therapeutic benefit.
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Affiliation(s)
- Kristopher T Kahle
- Department of Neurosurgery, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA
- Howard Hughes Medical Institute, Department of Cardiology, Manton Center for Orphan Disease Research, Boston Children's Hospital, Boston, MA 02115, USA
| | - Tarek Z Deeb
- Department of Neuroscience, Tufts University School of Medicine, Boston, MA 02111, USA
| | - Martin Puskarjov
- Department of Biosciences and Neuroscience Center, University of Helsinki, FI-00014 Helsinki, Finland
| | - Liliya Silayeva
- Department of Neuroscience, Tufts University School of Medicine, Boston, MA 02111, USA
| | - Bo Liang
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA
| | - Kai Kaila
- Department of Biosciences and Neuroscience Center, University of Helsinki, FI-00014 Helsinki, Finland
| | - Stephen J Moss
- Department of Neuroscience, Tufts University School of Medicine, Boston, MA 02111, USA
- Department of Neuroscience, Physiology and Pharmacology, University College, London, WC1E 6BT, UK
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181
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The known knowns of microglia–neuronal signalling in neuropathic pain. Neurosci Lett 2013; 557 Pt A:37-42. [DOI: 10.1016/j.neulet.2013.08.037] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2013] [Accepted: 08/16/2013] [Indexed: 12/30/2022]
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182
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Sawano E, Takahashi M, Negishi T, Tashiro T. Thyroid hormone-dependent development of the GABAergic pre- and post-synaptic components in the rat hippocampus. Int J Dev Neurosci 2013; 31:751-61. [PMID: 24076339 DOI: 10.1016/j.ijdevneu.2013.09.007] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2013] [Revised: 08/30/2013] [Accepted: 09/17/2013] [Indexed: 10/26/2022] Open
Abstract
Thyroid hormone (TH) plays essential roles in normal brain development mainly by regulating gene expression through binding to specific nuclear receptors which serve as transcription factors. Previous studies showed that perinatal deficiency of TH or impairment of its signaling severely affect brain development, especially the development of the γ-aminobutyric acid (GABA) system, but cellular and molecular targets of the hormone are only partly uncovered. In the present study, we focused on the developing rat hippocampus which was confirmed to be one of the regions highly sensitive to TH status, and found two new targets of the hormone among the pre- and post-synaptic components of the GABAergic system. One was glutamic acid decarboxylase 65 (GAD65), the protein level of which was reduced to less than 50% of control in the hippocampus of hypothyroid rats (obtained by administering 0.025% methimazole in drinking water to pregnant dams from gestational day 15 until 4 weeks postpartum) and recovered to control levels by daily thyroxine-replacement after birth. Reduction in GAD65 protein was correlated immunohistochemically with a 37% reduction in the number of GAD65-positive cells as well as a reduction in GAD65-positive processes. In contrast, the other GAD isotype, GAD67, was not affected by TH status. A subpopulation of GABAergic neurons containing parvalbumin was also confirmed to be highly dependent on TH status. The second target of thyroid hormone was neuron-specific K(+)/Cl(-) co-transporter, KCC2, which is responsible for switching of GABA action from excitatory to inhibitory. In the euthyroid hippocampus, a sharp rise of kcc2 expression was observed at postnatal day (PND)10 which was followed by a large increase in KCC2 protein at PND15. This transient rise in kcc2 expression was completely suppressed by hypothyroidism, resulting in nearly 80% reduction in KCC2 protein at PND15. These results indicate that the development of GABAergic terminals and the excitatory to inhibitory maturation of GABA signaling are strongly dependent on TH.
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Affiliation(s)
- Erika Sawano
- Department of Chemistry and Biological Science, School of Science and Engineering, Aoyama Gakuin University, 5-10-1 Fuchinobe, Chou-ku, Sagamihara, Kanagawa 252-5258, Japan.
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183
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Activity-dependent regulation of the K/Cl transporter KCC2 membrane diffusion, clustering, and function in hippocampal neurons. J Neurosci 2013; 33:15488-503. [PMID: 24068817 DOI: 10.1523/jneurosci.5889-12.2013] [Citation(s) in RCA: 82] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The neuronal K/Cl transporter KCC2 exports chloride ions and thereby influences the efficacy and polarity of GABA signaling in the brain. KCC2 is also critical for dendritic spine morphogenesis and the maintenance of glutamatergic transmission in cortical neurons. Because KCC2 plays a pivotal role in the function of central synapses, it is of particular importance to understand the cellular and molecular mechanisms underlying its regulation. Here, we studied the impact of membrane diffusion and clustering on KCC2 function. KCC2 forms clusters in the vicinity of both excitatory and inhibitory synapses. Using quantum-dot-based single-particle tracking on rat primary hippocampal neurons, we show that KCC2 is slowed down and confined at excitatory and inhibitory synapses compared with extrasynaptic regions. However, KCC2 escapes inhibitory synapses faster than excitatory synapses, reflecting stronger molecular constraints at the latter. Interfering with KCC2-actin interactions or inhibiting F-actin polymerization releases diffusion constraints on KCC2 at excitatory but not inhibitory synapses. Thus, F-actin constrains KCC2 diffusion at excitatory synapses, whereas KCC2 is confined at inhibitory synapses by a distinct mechanism. Finally, increased neuronal activity rapidly increases the diffusion coefficient and decreases the dwell time of KCC2 at excitatory synapses. This effect involves NMDAR activation, Ca(2+) influx, KCC2 S940 dephosphorylation and calpain protease cleavage of KCC2 and is accompanied by reduced KCC2 clustering and ion transport function. Thus, activity-dependent regulation of KCC2 lateral diffusion and clustering allows for a rapid regulation of chloride homeostasis in neurons.
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184
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Fouad K, Bennett DJ, Vavrek R, Blesch A. Long-term viral brain-derived neurotrophic factor delivery promotes spasticity in rats with a cervical spinal cord hemisection. Front Neurol 2013; 4:187. [PMID: 24312075 PMCID: PMC3832889 DOI: 10.3389/fneur.2013.00187] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2013] [Accepted: 11/04/2013] [Indexed: 12/31/2022] Open
Abstract
We have recently reported that rats with complete thoracic spinal cord injury (SCI) that received a combinatorial treatment, including viral brain-derived neurotrophic factor (BDNF) delivery in the spinal cord, not only showed enhanced axonal regeneration, but also deterioration of hind-limb motor function. By demonstrating that BDNF over-expression can trigger spasticity-like symptoms in a rat model of sacral SCI, we proposed a causal relationship between the observed spasticity-like symptoms (i.e., resistance to passive range of motion) and the over-expression of BDNF. The current study was originally designed to evaluate a comparable combined treatment for cervical SCI in the rat to improve motor recovery. Once again we found similar signs of spasticity involving clenching of the paws and wrist flexion. This finding changed the focus of the study and, we then explored whether this spasticity-like symptom is directly related to the over-expression of BDNF by administering a BDNF antagonist. Using electromyographic measurements we showed that this treatment gradually diminished the resistance to overcome forelimb flexion in an acute experiment. Thus, we conclude that neuro-excitatory effects of chronic BDNF delivery together with diminished descending control after SCI can result in adverse effects.
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Affiliation(s)
- Karim Fouad
- Rehabilitation Medicine, University of Alberta , Edmonton, AB , Canada
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185
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Sharp JW, Ross-Inta CM, Baccelli I, Payne JA, Rudell JB, Gietzen DW. Effects of essential amino acid deficiency: down-regulation of KCC2 and the GABAA receptor; disinhibition in the anterior piriform cortex. J Neurochem 2013; 127:520-30. [PMID: 24024616 PMCID: PMC3858386 DOI: 10.1111/jnc.12403] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2013] [Revised: 08/14/2013] [Accepted: 08/15/2013] [Indexed: 01/27/2023]
Abstract
The anterior piriform cortex (APC) is activated by, and is the brain area most sensitive to, essential (indispensable) amino acid (IAA) deficiency. The APC is required for the rapid (20 min) behavioral rejection of IAA deficient diets and increased foraging, both crucial adaptive functions supporting IAA homeostasis in omnivores. The biochemical mechanisms signaling IAA deficiency in the APC block initiation of translation in protein synthesis via uncharged tRNA and the general amino acid control kinase, general control nonderepressing kinase 2. Yet, how inhibition of protein synthesis activates the APC is unknown. The neuronal K(+) Cl(-) cotransporter, neural potassium chloride co-transporter (KCC2), and GABAA receptors are essential inhibitory elements in the APC with short plasmalemmal half-lives that maintain control in this highly excitable circuitry. After a single IAA deficient meal both proteins were reduced (vs. basal diet controls) in western blots of APC (but not neocortex or cerebellum) and in immunohistochemistry of APC. Furthermore, electrophysiological analyses support loss of inhibitory elements such as the GABAA receptor in this model. As the crucial inhibitory function of the GABAA receptor depends on KCC2 and the Cl(-) transmembrane gradient it establishes, these results suggest that loss of such inhibitory elements contributes to disinhibition of the APC in IAA deficiency. The circuitry of the anterior piriform cortex (APC) is finely balanced between excitatory (glutamate, +) and inhibitory (GABA, -) transmission. GABAA receptors use Cl(-), requiring the neural potassium chloride co-transporter (KCC2). Both are rapidly turning-over proteins, dependent on protein synthesis for repletion. In IAA (indispensable amino acid) deficiency, within 20 min, blockade of protein synthesis prevents restoration of these inhibitors; they are diminished; disinhibition ensues. GCN2 = general control non-derepressing kinase 2, eIF2α = α-subunit of the eukaryotic initiation factor 2.
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Affiliation(s)
- James W. Sharp
- Department of Anatomy, Physiology and Cell Biology, School of Veterinary Medicine, University of California, Davis, One Shields Ave, Davis CA 95616, USA, Voice +530-752-1174, Fax +530-752-7690
| | - Catherine M. Ross-Inta
- Department of Anatomy, Physiology and Cell Biology, School of Veterinary Medicine, University of California, Davis, One Shields Ave, Davis CA 95616, USA, Voice +530-752-1174, Fax +530-752-7690
| | - Irène Baccelli
- Department of Anatomy, Physiology and Cell Biology, School of Veterinary Medicine, University of California, Davis, One Shields Ave, Davis CA 95616, USA, Voice +530-752-1174, Fax +530-752-7690
| | - John A. Payne
- Physiology and Membrane Biology, School of Medicine, University of California, Davis, CA 95616, USA, Voice +1 530 752 3336, FAX +1 530 752 5423
| | - John B. Rudell
- Department of Anatomy, Physiology and Cell Biology, School of Veterinary Medicine, University of California, Davis, One Shields Ave, Davis CA 95616, USA, Voice +530-752-1174, Fax +530-752-7690
| | - Dorothy W. Gietzen
- Department of Anatomy, Physiology and Cell Biology, School of Veterinary Medicine, University of California, Davis, One Shields Ave, Davis CA 95616, USA, Voice +530-752-1174, Fax +530-752-7690
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186
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Gagnon M, Bergeron MJ, Lavertu G, Castonguay A, Tripathy S, Bonin RP, Perez-Sanchez J, Boudreau D, Wang B, Dumas L, Valade I, Bachand K, Jacob-Wagner M, Tardif C, Kianicka I, Isenring P, Attardo G, Coull JA, De Koninck Y. Chloride extrusion enhancers as novel therapeutics for neurological diseases. Nat Med 2013; 19:1524-8. [PMID: 24097188 PMCID: PMC4005788 DOI: 10.1038/nm.3356] [Citation(s) in RCA: 238] [Impact Index Per Article: 21.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2013] [Accepted: 08/21/2013] [Indexed: 12/19/2022]
Abstract
The K(+)-Cl(-) cotransporter KCC2 is responsible for maintaining low Cl(-) concentration in neurons of the central nervous system (CNS), which is essential for postsynaptic inhibition through GABA(A) and glycine receptors. Although no CNS disorders have been associated with KCC2 mutations, loss of activity of this transporter has emerged as a key mechanism underlying several neurological and psychiatric disorders, including epilepsy, motor spasticity, stress, anxiety, schizophrenia, morphine-induced hyperalgesia and chronic pain. Recent reports indicate that enhancing KCC2 activity may be the favored therapeutic strategy to restore inhibition and normal function in pathological conditions involving impaired Cl(-) transport. We designed an assay for high-throughput screening that led to the identification of KCC2 activators that reduce intracellular chloride concentration ([Cl(-)]i). Optimization of a first-in-class arylmethylidine family of compounds resulted in a KCC2-selective analog (CLP257) that lowers [Cl(-)]i. CLP257 restored impaired Cl(-) transport in neurons with diminished KCC2 activity. The compound rescued KCC2 plasma membrane expression, renormalized stimulus-evoked responses in spinal nociceptive pathways sensitized after nerve injury and alleviated hypersensitivity in a rat model of neuropathic pain. Oral efficacy for analgesia equivalent to that of pregabalin but without motor impairment was achievable with a CLP257 prodrug. These results validate KCC2 as a druggable target for CNS diseases.
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Affiliation(s)
- Martin Gagnon
- Institut universitaire en santé mentale de Québec, Qc
- Department of Psychiatry & Neuroscience, Université Laval, Québec, Qc
- Chlorion Pharma, Inc. Laval, Qc
| | - Marc J. Bergeron
- Institut universitaire en santé mentale de Québec, Qc
- Department of Psychiatry & Neuroscience, Université Laval, Québec, Qc
| | - Guillaume Lavertu
- Institut universitaire en santé mentale de Québec, Qc
- Department of Psychiatry & Neuroscience, Université Laval, Québec, Qc
| | - Annie Castonguay
- Institut universitaire en santé mentale de Québec, Qc
- Department of Psychiatry & Neuroscience, Université Laval, Québec, Qc
| | | | - Robert P. Bonin
- Institut universitaire en santé mentale de Québec, Qc
- Department of Psychiatry & Neuroscience, Université Laval, Québec, Qc
| | - Jimena Perez-Sanchez
- Institut universitaire en santé mentale de Québec, Qc
- Department of Psychiatry & Neuroscience, Université Laval, Québec, Qc
| | - Dominic Boudreau
- Institut universitaire en santé mentale de Québec, Qc
- Department of Psychiatry & Neuroscience, Université Laval, Québec, Qc
| | | | | | | | - Karine Bachand
- Institut universitaire en santé mentale de Québec, Qc
- Department of Psychiatry & Neuroscience, Université Laval, Québec, Qc
| | | | - Christian Tardif
- Institut universitaire en santé mentale de Québec, Qc
- Graduate program in biophotonics, Université Laval, Québec, Qc
| | | | - Paul Isenring
- Centre de recherche du Centre Hospitalier Universitaire de Québec, Qc
| | | | | | - Yves De Koninck
- Institut universitaire en santé mentale de Québec, Qc
- Department of Psychiatry & Neuroscience, Université Laval, Québec, Qc
- Graduate program in biophotonics, Université Laval, Québec, Qc
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187
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A novel prophylactic effect of furosemide treatment on autosomal dominant nocturnal frontal lobe epilepsy (ADNFLE). Epilepsy Res 2013; 107:127-37. [DOI: 10.1016/j.eplepsyres.2013.08.018] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2013] [Revised: 05/27/2013] [Accepted: 08/08/2013] [Indexed: 11/17/2022]
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188
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Bercier V. WNK1/HSN2 isoform and the regulation of KCC2 activity. Rare Dis 2013; 1:e26537. [PMID: 25003007 PMCID: PMC3933052 DOI: 10.4161/rdis.26537] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2013] [Revised: 09/08/2013] [Accepted: 09/18/2013] [Indexed: 01/05/2023] Open
Abstract
Hereditary sensory and autonomic neuropathy type 2 is a rare autosomal recessive pathology presenting with early onset peripheral sensory defects. It arises from mutations affecting a specific isoform of the WNK1 kinase (with-no-lysine protein kinase 1) termed WNK1/HSN2. The role of WNK1 in the nervous system is not well understood. In our recent paper, we examined the effect of a pathological loss-of-function of the Wnk1/Hsn2 isoform on the development of the peripheral nervous system of the zebrafish embryo. Upon Wnk1/Hsn2 silencing using antisense morpholino oligonucleotides, we observed defects in the development of the sensory peripheral lateral line (PLL). Phenotypical embryos were also found to overexpress RNA for potassium-chloride cotransporter 2 (KCC2), a downstream target of WNK1 phosphorylation. Injection of recombinant mRNA for active KCC2, but not for inactive mutant KCC2-C568A, replicated the PLL defects observed in wnk1/hsn2 deficient animals, suggesting an essential role for WNK1/HSN2 in KCC2 regulation.
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Affiliation(s)
- Valérie Bercier
- Institut Curie; Centre de Recherche; CNRS UMR 3215/INSERM U934; Paris, France
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189
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Ferrini F, De Koninck Y. Microglia control neuronal network excitability via BDNF signalling. Neural Plast 2013; 2013:429815. [PMID: 24089642 PMCID: PMC3780625 DOI: 10.1155/2013/429815] [Citation(s) in RCA: 239] [Impact Index Per Article: 21.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2013] [Accepted: 07/28/2013] [Indexed: 12/27/2022] Open
Abstract
Microglia-neuron interactions play a crucial role in several neurological disorders characterized by altered neural network excitability, such as epilepsy and neuropathic pain. While a series of potential messengers have been postulated as substrates of the communication between microglia and neurons, including cytokines, purines, prostaglandins, and nitric oxide, the specific links between messengers, microglia, neuronal networks, and diseases have remained elusive. Brain-derived neurotrophic factor (BDNF) released by microglia emerges as an exception in this riddle. Here, we review the current knowledge on the role played by microglial BDNF in controlling neuronal excitability by causing disinhibition. The efforts made by different laboratories during the last decade have collectively provided a robust mechanistic paradigm which elucidates the mechanisms involved in the synthesis and release of BDNF from microglia, the downstream TrkB-mediated signals in neurons, and the biophysical mechanism by which disinhibition occurs, via the downregulation of the K⁺-Cl⁻ cotransporter KCC2, dysrupting Cl⁻ homeostasis, and hence the strength of GABA(A)- and glycine receptor-mediated inhibition. The resulting altered network activity appears to explain several features of the associated pathologies. Targeting the molecular players involved in this canonical signaling pathway may lead to novel therapeutic approach for ameliorating a wide array of neural dysfunctions.
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Affiliation(s)
- Francesco Ferrini
- Department of Veterinary Sciences, University of Turin, Grugliasco, 10095 Turin, Italy
| | - Yves De Koninck
- Institut Universitaire en Santé Mentale de Québec, Québec, QC, Canada G1J 2G3
- Department of Psychiatry and Neuroscience, Université Laval, Québec, QC, Canada G13 7P4
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190
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Satoh H, Qu L, Suzuki H, Saitow F. Depolarization-induced depression of inhibitory transmission in cerebellar Purkinje cells. Physiol Rep 2013; 1:e00061. [PMID: 24303140 PMCID: PMC3835016 DOI: 10.1002/phy2.61] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2013] [Revised: 07/24/2013] [Accepted: 07/25/2013] [Indexed: 11/07/2022] Open
Abstract
Several forms of depolarization-induced plasticity in inhibitory transmission have been reported to occur in cerebellar Purkinje cells (PCs), namely depolarization-induced suppression of inhibition (DSI), depolarization-induced potentiation of inhibition (DPI), and rebound potentiation (RP). Here, we describe another form of synaptic plasticity for gamma-amino butyric acid (GABA)ergic transmission in PCs. Immediately following depolarization trains in a PC, evoked inhibitory postsynaptic currents (eIPSCs) changed their direction from outward to inward currents under a recording condition in which eIPSCs were elicited as an outward current. Subsequently, the eIPSC amplitude remained depressed (depolarization-induced depression of inhibition [DDI]) for more than 20 min under the blockade of cannabinoid and N-methyl-D-aspartic acid (NMDA) receptor-mediated DSI and DPI, respectively. This DDI was completely abolished by intracellular infusion of the fast Ca(2+)-chelating agent BAPTA and by inhibition of Ca(2+)/calmodulin-dependent protein kinase II (CaMKII). Furthermore, DDI was strongly suppressed by calcium-activated chloride channel (CaCC) blockers, while an inhibitor of cation-chloride cotransporters (CCCs) partially blocked DDI during the early phase. Exogenous GABA-induced inhibition of spontaneous spike activity was attenuated in ∼50% of the PCs by climbing fiber stimulation-induced depolarization. These results suggest that activation of both CaCCs and CCCs was necessary for alteration of [Cl(-)]i after activation of CaMKII following elevation of [Ca(2+)]i in PCs. DDI may provide another mechanism for regulation of inhibitory inputs to PCs within the neuronal networks of the cerebellar cortex.
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Affiliation(s)
- Hiromasa Satoh
- Department of Pharmacology, Nippon Medical School Tokyo, 113-8602, Japan
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191
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Nardou R, Ferrari DC, Ben-Ari Y. Mechanisms and effects of seizures in the immature brain. Semin Fetal Neonatal Med 2013; 18:175-84. [PMID: 23702158 DOI: 10.1016/j.siny.2013.02.003] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
The developing immature brain is not simply a small adult brain but rather possesses unique physiological properties. These include neuronal ionic currents that differ markedly from those in the adult brain, typically being longer-lasting and less selective. This enables immature heterogeneous neurons to connect and fire together but at the same time, along with other features may contribute to the enhanced propensity of the developing brain to become epileptic. Indeed, immature neurons tend to readily synchronize and thus generate seizures. Here, we review the differences between the immature and adult brain, with particular focus on the developmental sequence of γ-aminobutyric acid that excites immature neurons while being inhibitory in the normal adult brain. We review the mechanisms underlying the developmental changes to intracellular chloride levels, as well as how epileptiform activity can drive pathologic changes to chloride balance in the brain. We show that regulation of intracellular chloride is one important factor that underlies both the ease with which seizures can be generated and the facilitation of further seizures. We stress in particular the importance of understanding normal developmental sequences and how they are interrupted by seizures and other insults, and how this knowledge has led to the identification of potential novel treatments for conditions such as neonatal seizures.
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192
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Huberfeld G, Le Duigou C, Le Van Quyen M, Navarro V, Baulac M, Miles R. The paradox of the paroxysm: can seizure precipitants help explain human ictogenesis? Neuroscientist 2013; 19:523-40. [PMID: 23881918 DOI: 10.1177/1073858413497430] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
An epileptic brain is permanently in a diseased state, but seizures occur rarely and without warning. Here we examine this paradox, common to paroxysmal diseases. We review the problem in the context of the prototypic acquired epilepsies of the medial temporal lobe. We ask how an epileptic temporal lobe differs from a healthy one and examine biological mechanisms that may explain the transition to seizure. Attempts to predict seizure timing from analyses of brain electrical activity suggest that the neurological processes involved may be initiated significantly before a seizure. Furthermore, whereas seizures are said to occur without warning, some patients say they know when a seizure is imminent. Several factors, including sleep deprivation, oscillations in hormonal levels, or withdrawal from drugs, increase the probability of a seizure. We ask whether these seizure precipitants might act through common neuronal mechanisms. Several precipitating factors seem to involve relief from a neurosteroid modulation of gamma-amino butyric acid receptor type A (GABAA) receptors. We propose tests of this hypothesis.
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Affiliation(s)
- Gilles Huberfeld
- INSERM U975, Institut du Cerveau et la Moëlle Epinière, Paris, France
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193
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Löscher W, Puskarjov M, Kaila K. Cation-chloride cotransporters NKCC1 and KCC2 as potential targets for novel antiepileptic and antiepileptogenic treatments. Neuropharmacology 2013; 69:62-74. [PMID: 22705273 DOI: 10.1016/j.neuropharm.2012.05.045] [Citation(s) in RCA: 200] [Impact Index Per Article: 18.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2012] [Revised: 05/22/2012] [Accepted: 05/28/2012] [Indexed: 12/31/2022]
Abstract
In cortical and hippocampal neurons, cation-chloride cotransporters (CCCs) control the reversal potential (EGABA) of GABAA receptor-mediated current and voltage responses and, consequently, they modulate the efficacy of GABAergic inhibition. Two members of the CCC family, KCC2 (the major neuron-specific K-Cl cotransporter; KCC isoform 2) and NKCC1 (the Na-K-2Cl cotransporter isoform 1 which is expressed in both neurons and glial cells) have attracted much interest in studies on GABAergic signaling under both normal and pathophysiological conditions, such as epilepsy. There is tentative evidence that loop diuretic compounds such as furosemide and bumetanide may have clinically relevant antiepileptic actions, especially when administered in combination with conventional GABA-mimetic drugs such as phenobarbital. Furosemide is a non-selective inhibitor of CCCs while at low concentrations bumetanide is selective for NKCCs. Search for novel antiepileptic drugs (AEDs) is highly motivated especially for the treatment of neonatal seizures which are often resistant to, or even aggravated by conventional AEDs. This review shows that the antiepileptic effects of loop diuretics described in the pertinent literature are based on widely heterogeneous mechanisms ranging from actions on both neuronal NKCC1 and KCC2 to modulation of the brain extracellular volume fraction. A promising strategy for the development of novel CCC-blocking AEDs is based on prodrugs that are activated following their passage across the blood-brain barrier. This article is part of the Special Issue entitled 'New Targets and Approaches to the Treatment of Epilepsy'.
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Affiliation(s)
- Wolfgang Löscher
- Department of Pharmacology, Toxicology and Pharmacy, University of Veterinary Medicine Hannover, Hannover, Germany.
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194
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Shibasaki M, Masukawa D, Ishii K, Yamagishi Y, Mori T, Suzuki T. Involvement of the K+-Cl- co-transporter KCC2 in the sensitization to morphine-induced hyperlocomotion under chronic treatment with zolpidem in the mesolimbic system. J Neurochem 2013; 125:747-55. [PMID: 23565710 DOI: 10.1111/jnc.12258] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2012] [Revised: 03/14/2013] [Accepted: 03/25/2013] [Indexed: 11/30/2022]
Abstract
Benzodiazepines are commonly used as sedatives, sleeping aids, and anti-anxiety drugs. However, chronic treatment with benzodiazepines is known to induce dependence, which is considered related to neuroplastic changes in the mesolimbic system. This study investigated the involvement of K(+) -Cl(-) co-transporter 2 (KCC2) in the sensitization to morphine-induced hyperlocomotion after chronic treatment with zolpidem [a selective agonist of γ-aminobutyric acid A-type receptor (GABAA R) α1 subunit]. In this study, chronic treatment with zolpidem enhanced morphine-induced hyperlocomotion, which is accompanied by the up-regulation of KCC2 in the limbic forebrain. We also found that chronic treatment with zolpidem induced the down-regulation of protein phosphatase-1 (PP-1) as well as the up-regulation of phosphorylated protein kinase C γ (pPKCγ). Furthermore, PP-1 directly associated with KCC2 and pPKCγ, whereas pPKCγ did not associate with KCC2. On the other hand, pre-treatment with furosemide (a KCC2 inhibitor) suppressed the enhancing effects of zolpidem on morphine-induced hyperlocomotion. These results suggest that the mesolimbic dopaminergic system could be amenable to neuroplastic change through a pPKCγ-PP-1-KCC2 pathway by chronic treatment with zolpidem.
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Affiliation(s)
- Masahiro Shibasaki
- Department of Toxicology, Hoshi University School of Pharmacy and Pharmaceutical Sciences, Tokyo 142-8501, Japan
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195
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Lacoh CM, Bodogan T, Kaila K, Fiumelli H, Vutskits L. General anaesthetics do not impair developmental expression of the KCC2 potassium-chloride cotransporter in neonatal rats during the brain growth spurt. Br J Anaesth 2013; 110 Suppl 1:i10-8. [PMID: 23533251 DOI: 10.1093/bja/aet063] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2023] Open
Abstract
BACKGROUND The developmental transition from depolarizing to hyperpolarizing γ-aminobutyric acid-mediated neurotransmission is primarily mediated by an increase in the amount of the potassium-chloride cotransporter KCC2 during early postnatal life. However, it is not known whether early neuronal activity plays a modulatory role in the expression of total KCC2 mRNA and protein in the immature brain. As general anaesthetics are powerful modulators of neuronal activity, the purpose of this study was to explore how these drugs affect KCC2 expression during the brain growth spurt. METHODS Wistar rat pups were exposed to either a single dose or 6 h of midazolam, propofol, or ketamine anaesthesia at postnatal days 0, 5, 10, or 15. KCC2 expression was assessed using immunoblotting, immunohistochemistry, or quantitative polymerase chain reaction analysis up to 3 days post-exposure in the medial prefrontal cortex. RESULTS There was a progressive and steep increase in the expression of KCC2 between birth and 2 weeks of age. Exposure to midazolam, propofol, or ketamine up to 6 h at any investigated stages of the brain growth spurt did not influence the expression of this cotransporter protein. CONCLUSION I.V. general anaesthetics do not seem to influence developmental expression of KCC2 during the brain growth spurt.
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Affiliation(s)
- C-M Lacoh
- Department of Anesthesiology, Pharmacology and Intensive Care, University Hospital of Geneva, 1211 Geneva, Switzerland
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196
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Ruiz CR, Shi J, Meffert MK. Transcript specificity in BDNF-regulated protein synthesis. Neuropharmacology 2013; 76 Pt C:657-63. [PMID: 23707639 DOI: 10.1016/j.neuropharm.2013.05.004] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2012] [Revised: 04/26/2013] [Accepted: 05/03/2013] [Indexed: 10/26/2022]
Abstract
Brain-derived neurotrophic factor (BDNF) is a critical activity-dependent modulator of gene expression, which can regulate both transcription and translation. Several functions of BDNF, including the induction of dendrite outgrowth and long-term synaptic plasticity, are known to depend, in particular, upon the ability of BDNF to regulate protein synthesis. Although BDNF modestly increases total neuronal protein synthesis, substantial evidence indicates that BDNF induces the translation of only a small subset of expressed mRNAs and demonstrates an extraordinary degree of transcript specificity. The mechanism by which BDNF selectively upregulates the translation of only a discrete group of mRNAs is of intrinsic importance to its trophic function in promoting neuronal growth and plasticity, and is the focus of this review. This article is part of the Special Issue entitled 'BDNF Regulation of Synaptic Structure, Function, and Plasticity'.
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Affiliation(s)
- Claudia R Ruiz
- Solomon H. Snyder Department of Neuroscience, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
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197
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Abstract
Epilepsy is a prevalent neurological disorder associated with significant morbidity and mortality, but the only available drug therapies target its symptoms rather than the underlying cause. The process that links brain injury or other predisposing factors to the subsequent emergence of epilepsy is termed epileptogenesis. Substantial research has focused on elucidating the mechanisms of epileptogenesis so as to identify more specific targets for intervention, with the hope of preventing epilepsy before seizures emerge. Recent work has yielded important conceptual advances in this field. We suggest that such insights into the mechanisms of epileptogenesis converge at the level of cortical circuit dysfunction.
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198
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Synaptic plasticity by antidromic firing during hippocampal network oscillations. Proc Natl Acad Sci U S A 2013; 110:5175-80. [PMID: 23479613 DOI: 10.1073/pnas.1210735110] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Learning and other cognitive tasks require integrating new experiences into context. In contrast to sensory-evoked synaptic plasticity, comparatively little is known of how synaptic plasticity may be regulated by intrinsic activity in the brain, much of which can involve nonclassical modes of neuronal firing and integration. Coherent high-frequency oscillations of electrical activity in CA1 hippocampal neurons [sharp-wave ripple complexes (SPW-Rs)] functionally couple neurons into transient ensembles. These oscillations occur during slow-wave sleep or at rest. Neurons that participate in SPW-Rs are distinguished from adjacent nonparticipating neurons by firing action potentials that are initiated ectopically in the distal region of axons and propagate antidromically to the cell body. This activity is facilitated by GABA(A)-mediated depolarization of axons and electrotonic coupling. The possible effects of antidromic firing on synaptic strength are unknown. We find that facilitation of spontaneous SPW-Rs in hippocampal slices by increasing gap-junction coupling or by GABA(A)-mediated axon depolarization resulted in a reduction of synaptic strength, and electrical stimulation of axons evoked a widespread, long-lasting synaptic depression. Unlike other forms of synaptic plasticity, this synaptic depression is not dependent upon synaptic input or glutamate receptor activation, but rather requires L-type calcium channel activation and functional gap junctions. Synaptic stimulation delivered after antidromic firing, which was otherwise too weak to induce synaptic potentiation, triggered a long-lasting increase in synaptic strength. Rescaling synaptic weights in subsets of neurons firing antidromically during SPW-Rs might contribute to memory consolidation by sharpening specificity of subsequent synaptic input and promoting incorporation of novel information.
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199
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Liu Q, Wong-Riley MTT. Postnatal development of brain-derived neurotrophic factor (BDNF) and tyrosine protein kinase B (TrkB) receptor immunoreactivity in multiple brain stem respiratory-related nuclei of the rat. J Comp Neurol 2013; 521:109-29. [PMID: 22678720 DOI: 10.1002/cne.23164] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2012] [Revised: 04/23/2012] [Accepted: 06/01/2012] [Indexed: 11/11/2022]
Abstract
Previously, we found a transient imbalance between suppressed excitation and enhanced inhibition in the respiratory network of the rat around postnatal days (P) 12-13, a critical period when the hypoxic ventilatory response is at its weakest. The mechanism underlying the imbalance is poorly understood. Brain-derived neurotrophic factor (BDNF) and its tyrosine protein kinase B (TrkB) receptors are known to potentiate glutamatergic and attenuate gamma-aminobutyric acid (GABA)ergic neurotransmission, and BDNF is essential for respiratory development. We hypothesized that the excitation-inhibition imbalance during the critical period stemmed from a reduced expression of BDNF and TrkB at that time within respiratory-related nuclei of the brain stem. An in-depth, semiquantitative immunohistochemical study was undertaken in seven respiratory-related brain stem nuclei and one nonrespiratory nucleus in P0-21 rats. The results indicate that the expressions of BDNF and TrkB: 1) in the pre-Bötzinger complex, nucleus ambiguus, commissural and ventrolateral subnuclei of solitary tract nucleus, and retrotrapezoid nucleus/parafacial respiratory group were significantly reduced at P12, but returned to P11 levels by P14; 2) in the lateral paragigantocellular nucleus and parapyramidal region were increased from P0 to P7, but were strikingly reduced at P10 and plateaued thereafter; and 3) in the nonrespiratory cuneate nucleus showed a gentle plateau throughout the first 3 postnatal weeks, with only a slight decline of BDNF expression after P11. Thus, the significant downregulation of both BDNF and TrkB in respiratory-related nuclei during the critical period may form the basis of, or at least contribute to, the inhibitory-excitatory imbalance within the respiratory network during this time.
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Affiliation(s)
- Qiuli Liu
- Department of Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, Milwaukee, Wisconsin 53226, USA
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200
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Pavlov I, Kaila K, Kullmann DM, Miles R. Cortical inhibition, pH and cell excitability in epilepsy: what are optimal targets for antiepileptic interventions? J Physiol 2013; 591:765-74. [PMID: 22890709 PMCID: PMC3591695 DOI: 10.1113/jphysiol.2012.237958] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2012] [Accepted: 08/10/2012] [Indexed: 12/14/2022] Open
Abstract
Epilepsy is characterised by the propensity of the brain to generate spontaneous recurrent bursts of excessive neuronal activity, seizures. GABA-mediated inhibition is critical for restraining neuronal excitation in the brain, and therefore potentiation of GABAergic neurotransmission is commonly used to prevent seizures. However, data obtained in animal models of epilepsy and from human epileptic tissue suggest that GABA-mediated signalling contributes to interictal and ictal activity. Prolonged activation of GABA(A) receptors during epileptiform bursts may even initiate a shift in GABAergic neurotransmission from inhibitory to excitatory and so have a proconvulsant action. Direct targeting of the membrane mechanisms that reduce spiking in glutamatergic neurons may better control neuronal excitability in epileptic tissue. Manipulation of brain pH may be a promising approach and recent advances in gene therapy and optogenetics seem likely to provide further routes to effective therapeutic intervention.
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Affiliation(s)
- Ivan Pavlov
- Department of Clinical and Experimental Epilepsy, UCL Institute of Neurology, London WC1N 3BG, UK.
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