1
|
Trofimova AM, Amakhin DV, Postnikova TY, Tiselko VS, Alekseev A, Podoliak E, Gordeliy VI, Chizhov AV, Zaitsev AV. Light-Driven Sodium Pump as a Potential Tool for the Control of Seizures in Epilepsy. Mol Neurobiol 2024; 61:4691-4704. [PMID: 38114761 DOI: 10.1007/s12035-023-03865-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2023] [Accepted: 12/06/2023] [Indexed: 12/21/2023]
Abstract
The marine flavobacterium Krokinobactereikastus light-driven sodium pump (KR2) generates an outward sodium ion current under 530 nm light stimulation, representing a promising optogenetic tool for seizure control. However, the specifics of KR2 application to suppress epileptic activity have not yet been addressed. In the present study, we investigated the possibility of KR2 photostimulation to suppress epileptiform activity in mouse brain slices using the 4-aminopyrindine (4-AP) model. We injected the adeno-associated viral vector (AAV-PHP.eB-hSyn-KR2-YFP) containing the KR2 sodium pump gene enhanced with appropriate trafficking tags. KR2 expression was observed in the lateral entorhinal cortex and CA1 hippocampus. Using whole-cell patch clamp in mouse brain slices, we show that KR2, when stimulated with LED light, induces a substantial hyperpolarization of entorhinal neurons. However, continuous photostimulation of KR2 does not interrupt ictal discharges in mouse entorhinal cortex slices induced by a solution containing 4-AP. KR2-induced hyperpolarization strongly activates neuronal HCN channels. Consequently, turning off photostimulation resulted in HCN channel-mediated rebound depolarization accompanied by a transient increase in spontaneous network activity. Using low-frequency pulsed photostimulation, we induced the generation of short HCN channel-mediated discharges that occurred in response to the light stimulus being turned off; these discharges reliably interrupt ictal activity. Thus, low-frequency pulsed photostimulation of KR2 can be considered as a potential tool for controlling epileptic seizures.
Collapse
Affiliation(s)
- Alina M Trofimova
- Sechenov Institute of Evolutionary Physiology and Biochemistry, Saint Petersburg, Russia
| | - Dmitry V Amakhin
- Sechenov Institute of Evolutionary Physiology and Biochemistry, Saint Petersburg, Russia
| | - Tatyana Y Postnikova
- Sechenov Institute of Evolutionary Physiology and Biochemistry, Saint Petersburg, Russia
| | - Vasilii S Tiselko
- Sechenov Institute of Evolutionary Physiology and Biochemistry, Saint Petersburg, Russia
| | - Alexey Alekseev
- Research Center for Molecular Mechanisms of Aging and Age-Related Diseases, Moscow Institute of Physics and Technology (National Research University), Dolgoprudny, Russia
- Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, Göttingen, Germany
| | - Elizaveta Podoliak
- Research Center for Molecular Mechanisms of Aging and Age-Related Diseases, Moscow Institute of Physics and Technology (National Research University), Dolgoprudny, Russia
- Department of Ophthalmology, Universitäts-Augenklinik Bonn, University of Bonn, Bonn, Germany
| | - Valentin I Gordeliy
- Research Center for Molecular Mechanisms of Aging and Age-Related Diseases, Moscow Institute of Physics and Technology (National Research University), Dolgoprudny, Russia
- Institut de Biologie Structurale (IBS), Université Grenoble Alpes, CEA, CNRS, Grenoble, France
| | - Anton V Chizhov
- Sechenov Institute of Evolutionary Physiology and Biochemistry, Saint Petersburg, Russia
- MathNeuro Team, Inria Centre at Université Côte d'Azur, Sophia Antipolis, France
| | - Aleksey V Zaitsev
- Sechenov Institute of Evolutionary Physiology and Biochemistry, Saint Petersburg, Russia.
| |
Collapse
|
2
|
Zhao K, Li Y, Lai H, Niu R, Li H, He S, Su Z, Gui Y, Ren L, Yang X, Zhou L. Alterations in HCN1 expression and distribution during epileptogenesis in rats. Epilepsy Res 2024; 202:107355. [PMID: 38555654 DOI: 10.1016/j.eplepsyres.2024.107355] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2023] [Revised: 03/10/2024] [Accepted: 03/21/2024] [Indexed: 04/02/2024]
Abstract
BACKGROUND The hyperpolarization-activated cyclic nucleotide-gated cation channel (HCN1) is predominantly located in key regions associated with epilepsy, such as the neocortex and hippocampus. Under normal physiological conditions, HCN1 plays a crucial role in the excitatory and inhibitory regulation of neuronal networks. In temporal lobe epilepsy, the expression of HCN1 is decreased in the hippocampi of both animal models and patients. However, whether HCN1 expression changes during epileptogenesis preceding spontaneous seizures remains unclear. OBJECTIVE The aim of this study was to determine whether the expression of HCN1 is altered during the epileptic prodromal phase, thereby providing evidence for its role in epileptogenesis. METHODS We utilized a cobalt wire-induced rat epilepsy model to observe changes in HCN1 during epileptogenesis and epilepsy. Additionally, we also compared HCN1 alterations in epileptogenic tissues between cobalt wire- and pilocarpine-induced epilepsy rat models. Long-term video EEG recordings were used to confirm seizures development. Transcriptional changes, translation, and distribution of HCN1 were assessed using high-throughput transcriptome sequencing, total protein extraction, membrane and cytoplasmic protein fractionation, western blotting, immunohistochemistry, and immunofluorescence techniques. RESULTS In the cobalt wire-induced rat epilepsy model during the epileptogenesis phase, total HCN1 mRNA and protein levels were downregulated. Specifically, the membrane expression of HCN1 was decreased, whereas cytoplasmic HCN1 expression showed no significant change. The distribution of HCN1 in the distal dendrites of neurons decreased. During the epilepsy period, similar HCN1 alterations were observed in the neocortex of rats with cobalt wire-induced epilepsy and hippocampus of rats with lithium pilocarpine-induced epilepsy, including downregulation of mRNA levels, decreased total protein expression, decreased membrane expression, and decreased distal dendrite expression. CONCLUSIONS Alterations in HCN1 expression and distribution are involved in epileptogenesis beyond their association with seizure occurrence. Similarities in HCN1 alterations observed in epileptogenesis-related tissues from different models suggest a shared pathophysiological pathway in epileptogenesis involving HCN1 dysregulation. Therefore, the upregulation of HCN1 expression in neurons, maintenance of the HCN1 membrane, and distal dendrite distribution in neurons may represent promising disease-modifying strategies in epilepsy.
Collapse
Affiliation(s)
- Ke Zhao
- Department of Neurology, The Seventh Affiliated Hospital of Sun Yat-sen University, Shenzhen, China; Guangzhou National Laboratory, Guangzhou, China; Department of Neurology, The First Affiliated Hospital of Shenzhen University, Shenzhen Second People's Hospital, Shenzhen, China
| | - Yinchao Li
- Department of Neurology, The Seventh Affiliated Hospital of Sun Yat-sen University, Shenzhen, China
| | | | - Ruili Niu
- Guangzhou National Laboratory, Guangzhou, China
| | - Huifeng Li
- Guangzhou National Laboratory, Guangzhou, China
| | - Shipei He
- Guangzhou National Laboratory, Guangzhou, China
| | - Zhengwei Su
- Department of Neurology, The Seventh Affiliated Hospital of Sun Yat-sen University, Shenzhen, China
| | - Yue Gui
- Guangzhou National Laboratory, Guangzhou, China
| | - Lijie Ren
- Department of Neurology, The First Affiliated Hospital of Shenzhen University, Shenzhen Second People's Hospital, Shenzhen, China.
| | | | - Liemin Zhou
- Department of Neurology, The Seventh Affiliated Hospital of Sun Yat-sen University, Shenzhen, China.
| |
Collapse
|
3
|
Depolarization and Hyperexcitability of Cortical Motor Neurons after Spinal Cord Injury Associates with Reduced HCN Channel Activity. Int J Mol Sci 2023; 24:ijms24054715. [PMID: 36902146 PMCID: PMC10003573 DOI: 10.3390/ijms24054715] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2023] [Revised: 02/24/2023] [Accepted: 02/25/2023] [Indexed: 03/05/2023] Open
Abstract
A spinal cord injury (SCI) damages the axonal projections of neurons residing in the neocortex. This axotomy changes cortical excitability and results in dysfunctional activity and output of infragranular cortical layers. Thus, addressing cortical pathophysiology after SCI will be instrumental in promoting recovery. However, the cellular and molecular mechanisms of cortical dysfunction after SCI are poorly resolved. In this study, we determined that the principal neurons of the primary motor cortex layer V (M1LV), those suffering from axotomy upon SCI, become hyperexcitable following injury. Therefore, we questioned the role of hyperpolarization cyclic nucleotide gated channels (HCN channels) in this context. Patch clamp experiments on axotomized M1LV neurons and acute pharmacological manipulation of HCN channels allowed us to resolve a dysfunctional mechanism controlling intrinsic neuronal excitability one week after SCI. Some axotomized M1LV neurons became excessively depolarized. In those cells, the HCN channels were less active and less relevant to control neuronal excitability because the membrane potential exceeded the window of HCN channel activation. Care should be taken when manipulating HCN channels pharmacologically after SCI. Even though the dysfunction of HCN channels partakes in the pathophysiology of axotomized M1LV neurons, their dysfunctional contribution varies remarkably between neurons and combines with other pathophysiological mechanisms.
Collapse
|
4
|
Wu Y, Luo XD, Xiang T, Li SJ, Ma MG, Chen ML. Activation of metabotropic glutamate receptor 1 regulates hippocampal CA1 region excitability in rats with status epilepticus by suppressing the HCN1 channel. Neural Regen Res 2023; 18:594-602. [DOI: 10.4103/1673-5374.350206] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
|
5
|
Depressive-like behaviors induced by chronic cerebral hypoperfusion associate with a dynamic change of GABA B1/B2 receptors expression in hippocampal CA1 region. Physiol Behav 2022; 254:113887. [PMID: 35724927 DOI: 10.1016/j.physbeh.2022.113887] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2022] [Revised: 05/07/2022] [Accepted: 06/16/2022] [Indexed: 11/21/2022]
Abstract
Cerebral ischemia could induce depressive-like behaviors; however, the alteration of gamma-aminobutyric acid receptors type B (GABAB) receptors in these pathological processes has not been extensively investigated. The aim of the current study was to document the behavioral change and the alteration of GABAB receptors in chronic cerebral hypoperfusion. The permanent occlusion of the bilateral common carotid arteries (two-vessel occlusion, 2VO) was performed to induce chronic cerebral ischemia (CCH). The depressive-like behaviors were evaluated with sucrose preference test, novelty suppress feeding test as well as forced swim test at 4, 8, and 12 weeks after the 2VO surgery. The total, surface and intracellular expressions of GABAB subunit 1 (GABAB1) and subunit 2 (GABAB2) in hippocampal CA1 were quantified by western blot. The depressive-like behaviors were observed in rats suffered from 4, 8, and 12 weeks 2VO in sucrose preference test, novelty suppress feeding test and forced swim test. In addition, the surface and total expression of GABAB1 in CA1 was reduced at 4 weeks after 2VO rather than 8 or 12 weeks. While the surface and total expression of GABAB2 in CA1 was decreased throughout the ischemia timeline (4, 8, and 12 weeks). Taken together, our findings suggested the potential roles of GABAB1 and GABAB2 subunits involved in depressive-like behaviors caused by chronic cerebral hypoperfusion.
Collapse
|
6
|
Kessi M, Peng J, Duan H, He H, Chen B, Xiong J, Wang Y, Yang L, Wang G, Kiprotich K, Bamgbade OA, He F, Yin F. The Contribution of HCN Channelopathies in Different Epileptic Syndromes, Mechanisms, Modulators, and Potential Treatment Targets: A Systematic Review. Front Mol Neurosci 2022; 15:807202. [PMID: 35663267 PMCID: PMC9161305 DOI: 10.3389/fnmol.2022.807202] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2021] [Accepted: 04/06/2022] [Indexed: 12/04/2022] Open
Abstract
Background Hyperpolarization-activated cyclic nucleotide-gated (HCN) current reduces dendritic summation, suppresses dendritic calcium spikes, and enables inhibitory GABA-mediated postsynaptic potentials, thereby suppressing epilepsy. However, it is unclear whether increased HCN current can produce epilepsy. We hypothesized that gain-of-function (GOF) and loss-of-function (LOF) variants of HCN channel genes may cause epilepsy. Objectives This systematic review aims to summarize the role of HCN channelopathies in epilepsy, update genetic findings in patients, create genotype–phenotype correlations, and discuss animal models, GOF and LOF mechanisms, and potential treatment targets. Methods The review was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement, for all years until August 2021. Results We identified pathogenic variants of HCN1 (n = 24), HCN2 (n = 8), HCN3 (n = 2), and HCN4 (n = 6) that were associated with epilepsy in 74 cases (43 HCN1, 20 HCN2, 2 HCN3, and 9 HCN4). Epilepsy was associated with GOF and LOF variants, and the mechanisms were indeterminate. Less than half of the cases became seizure-free and some developed drug-resistant epilepsy. Of the 74 cases, 12 (16.2%) died, comprising HCN1 (n = 4), HCN2 (n = 2), HCN3 (n = 2), and HCN4 (n = 4). Of the deceased cases, 10 (83%) had a sudden unexpected death in epilepsy (SUDEP) and 2 (16.7%) due to cardiopulmonary failure. SUDEP affected more adults (n = 10) than children (n = 2). HCN1 variants p.M234R, p.C329S, p.V414M, p.M153I, and p.M305L, as well as HCN2 variants p.S632W and delPPP (p.719–721), were associated with different phenotypes. HCN1 p.L157V and HCN4 p.R550C were associated with genetic generalized epilepsy. There are several HCN animal models, pharmacological targets, and modulators, but precise drugs have not been developed. Currently, there are no HCN channel openers. Conclusion We recommend clinicians to include HCN genes in epilepsy gene panels. Researchers should explore the possible underlying mechanisms for GOF and LOF variants by identifying the specific neuronal subtypes and neuroanatomical locations of each identified pathogenic variant. Researchers should identify specific HCN channel openers and blockers with high binding affinity. Such information will give clarity to the involvement of HCN channelopathies in epilepsy and provide the opportunity to develop targeted treatments.
Collapse
Affiliation(s)
- Miriam Kessi
- Department of Pediatrics, Xiangya Hospital, Central South University, Changsha, China
- Hunan Intellectual and Developmental Disabilities Research Center, Changsha, China
- Department of Pediatrics, Kilimanjaro Christian Medical University College, Moshi, Tanzania
| | - Jing Peng
- Department of Pediatrics, Xiangya Hospital, Central South University, Changsha, China
- Hunan Intellectual and Developmental Disabilities Research Center, Changsha, China
| | - Haolin Duan
- Department of Pediatrics, Xiangya Hospital, Central South University, Changsha, China
- Hunan Intellectual and Developmental Disabilities Research Center, Changsha, China
| | - Hailan He
- Department of Pediatrics, Xiangya Hospital, Central South University, Changsha, China
- Hunan Intellectual and Developmental Disabilities Research Center, Changsha, China
| | - Baiyu Chen
- Department of Pediatrics, Xiangya Hospital, Central South University, Changsha, China
- Hunan Intellectual and Developmental Disabilities Research Center, Changsha, China
| | - Juan Xiong
- Department of Pediatrics, Xiangya Hospital, Central South University, Changsha, China
- Hunan Intellectual and Developmental Disabilities Research Center, Changsha, China
| | - Ying Wang
- Department of Pediatrics, Xiangya Hospital, Central South University, Changsha, China
- Hunan Intellectual and Developmental Disabilities Research Center, Changsha, China
| | - Lifen Yang
- Department of Pediatrics, Xiangya Hospital, Central South University, Changsha, China
- Hunan Intellectual and Developmental Disabilities Research Center, Changsha, China
| | - Guoli Wang
- Department of Pediatrics, Xiangya Hospital, Central South University, Changsha, China
- Hunan Intellectual and Developmental Disabilities Research Center, Changsha, China
| | - Karlmax Kiprotich
- Department of Epidemiology and Medical Statistics, School of Public Health, Moi University, Eldoret, Kenya
| | - Olumuyiwa A. Bamgbade
- Department of Anesthesiology and Pharmacology, University of British Columbia, Vancouver, BC, Canada
| | - Fang He
- Department of Pediatrics, Xiangya Hospital, Central South University, Changsha, China
- Hunan Intellectual and Developmental Disabilities Research Center, Changsha, China
| | - Fei Yin
- Department of Pediatrics, Xiangya Hospital, Central South University, Changsha, China
- Hunan Intellectual and Developmental Disabilities Research Center, Changsha, China
- *Correspondence: Fei Yin
| |
Collapse
|
7
|
Yang C, Ni HY, Yin JJ, Zhou T, Gu QX, Chen TT, Cai CY. Atorvastatin ameliorates depressive behaviors via regulation of α7nAChR expression by PI3K/Akt-BDNF pathway in mice. Biochem Biophys Res Commun 2022; 593:57-64. [DOI: 10.1016/j.bbrc.2022.01.034] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2021] [Accepted: 01/08/2022] [Indexed: 12/27/2022]
|
8
|
Altered cardiac structure and function is related to seizure frequency in a rat model of chronic acquired temporal lobe epilepsy. Neurobiol Dis 2021; 159:105505. [PMID: 34520843 DOI: 10.1016/j.nbd.2021.105505] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2020] [Revised: 09/02/2021] [Accepted: 09/05/2021] [Indexed: 11/24/2022] Open
Abstract
OBJECTIVE This study aimed to prospectively examine cardiac structure and function in the kainic acid-induced post-status epilepticus (post-KA SE) model of chronic acquired temporal lobe epilepsy (TLE), specifically to examine for changes between the pre-epileptic, early epileptogenesis and the chronic epilepsy stages. We also aimed to examine whether any changes related to the seizure frequency in individual animals. METHODS Four hours of SE was induced in 9 male Wistar rats at 10 weeks of age, with 8 saline treated matched control rats. Echocardiography was performed prior to the induction of SE, two- and 10-weeks post-SE. Two weeks of continuous video-EEG and simultaneous ECG recordings were acquired for two weeks from 11 weeks post-KA SE. The video-EEG recordings were analyzed blindly to quantify the number and severity of spontaneous seizures, and the ECG recordings analyzed for measures of heart rate variability (HRV). PicroSirius red histology was performed to assess cardiac fibrosis, and intracellular Ca2+ levels and cell contractility were measured by microfluorimetry. RESULTS All 9 post-KA SE rats were demonstrated to have spontaneous recurrent seizures on the two-week video-EEG recording acquired from 11 weeks SE (seizure frequency ranging from 0.3 to 10.6 seizures/day with the seizure durations from 11 to 62 s), and none of the 8 control rats. Left ventricular wall thickness was thinner, left ventricular internal dimension was shorter, and ejection fraction was significantly decreased in chronically epileptic rats, and was negatively correlated to seizure frequency in individual rats. Diastolic dysfunction was evident in chronically epileptic rats by a decrease in mitral valve deceleration time and an increase in E/E` ratio. Measures of HRV were reduced in the chronically epileptic rats, indicating abnormalities of cardiac autonomic function. Cardiac fibrosis was significantly increased in epileptic rats, positively correlated to seizure frequency, and negatively correlated to ejection fraction. The cardiac fibrosis was not a consequence of direct effect of KA toxicity, as it was not seen in the 6/10 rats from separate cohort that received similar doses of KA but did not go into SE. Cardiomyocyte length, width, volume, and rate of cell lengthening and shortening were significantly reduced in epileptic rats. SIGNIFICANCE The results from this study demonstrate that chronic epilepsy in the post-KA SE rat model of TLE is associated with a progressive deterioration in cardiac structure and function, with a restrictive cardiomyopathy associated with myocardial fibrosis. Positive correlations between seizure frequency and the severity of the cardiac changes were identified. These results provide new insights into the pathophysiology of cardiac disease in chronic epilepsy, and may have relevance for the heterogeneous mechanisms that place these people at risk of sudden unexplained death.
Collapse
|
9
|
Dwivedi D, Bhalla US. Physiology and Therapeutic Potential of SK, H, and M Medium AfterHyperPolarization Ion Channels. Front Mol Neurosci 2021; 14:658435. [PMID: 34149352 PMCID: PMC8209339 DOI: 10.3389/fnmol.2021.658435] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2021] [Accepted: 04/13/2021] [Indexed: 12/19/2022] Open
Abstract
SK, HCN, and M channels are medium afterhyperpolarization (mAHP)-mediating ion channels. The three channels co-express in various brain regions, and their collective action strongly influences cellular excitability. However, significant diversity exists in the expression of channel isoforms in distinct brain regions and various subcellular compartments, which contributes to an equally diverse set of specific neuronal functions. The current review emphasizes the collective behavior of the three classes of mAHP channels and discusses how these channels function together although they play specialized roles. We discuss the biophysical properties of these channels, signaling pathways that influence the activity of the three mAHP channels, various chemical modulators that alter channel activity and their therapeutic potential in treating various neurological anomalies. Additionally, we discuss the role of mAHP channels in the pathophysiology of various neurological diseases and how their modulation can alleviate some of the symptoms.
Collapse
Affiliation(s)
- Deepanjali Dwivedi
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, GKVK Campus, Bengaluru, India.,Department of Neurobiology, Harvard Medical School, Boston, MA, United States.,Stanley Center at the Broad, Cambridge, MA, United States
| | - Upinder S Bhalla
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, GKVK Campus, Bengaluru, India
| |
Collapse
|
10
|
Testing broad-spectrum and isoform-preferring HCN channel blockers for anticonvulsant properties in mice. Epilepsy Res 2020; 168:106484. [DOI: 10.1016/j.eplepsyres.2020.106484] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2020] [Revised: 09/23/2020] [Accepted: 10/05/2020] [Indexed: 12/19/2022]
|
11
|
Hu JH, Malloy C, Hoffman DA. P38 Regulates Kainic Acid-Induced Seizure and Neuronal Firing via Kv4.2 Phosphorylation. Int J Mol Sci 2020; 21:ijms21165921. [PMID: 32824677 PMCID: PMC7460594 DOI: 10.3390/ijms21165921] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Revised: 08/06/2020] [Accepted: 08/14/2020] [Indexed: 01/23/2023] Open
Abstract
The subthreshold, transient A-type K+ current is a vital regulator of the excitability of neurons throughout the brain. In mammalian hippocampal pyramidal neurons, this current is carried primarily by ion channels comprising Kv4.2 α-subunits. These channels occupy the somatodendritic domains of these principle excitatory neurons and thus regulate membrane voltage relevant to the input-output efficacy of these cells. Owing to their robust control of membrane excitability and ubiquitous expression in the hippocampus, their dysfunction can alter network stability in a manner that manifests in recurrent seizures. Indeed, growing evidence implicates these channels in intractable epilepsies of the temporal lobe, which underscores the importance of determining the molecular mechanisms underlying their regulation and contribution to pathologies. Here, we describe the role of p38 kinase phosphorylation of a C-terminal motif in Kv4.2 in modulating hippocampal neuronal excitability and behavioral seizure strength. Using a combination of biochemical, single-cell electrophysiology, and in vivo seizure techniques, we show that kainic acid-induced seizure induces p38-mediated phosphorylation of Thr607 in Kv4.2 in a time-dependent manner. The pharmacological and genetic disruption of this process reduces neuronal excitability and dampens seizure intensity, illuminating a cellular cascade that may be targeted for therapeutic intervention to mitigate seizure intensity and progression.
Collapse
|
12
|
Chen C, Liu L, Shu YQ, Jing P, Lu Y, Zhang XX, Zong XG, Guo LJ, Li CJ. Blockade of HCN2 Channels Provides Neuroprotection Against Ischemic Injury via Accelerating Autophagic Degradation in Hippocampal Neurons. Neurosci Bull 2020; 36:875-894. [PMID: 32519067 PMCID: PMC7410947 DOI: 10.1007/s12264-020-00513-7] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2019] [Accepted: 02/16/2020] [Indexed: 01/25/2023] Open
Abstract
In the central nervous system, hyperpolarization-activated cyclic nucleotide-gated (HCN) channels are essential to maintain normal neuronal function. Recent studies have shown that HCN channels may be involved in the pathological process of ischemic brain injury, but the mechanisms remain unclear. Autophagy is activated in cerebral ischemia, but its role in cell death/survival remains controversial. In this study, our results showed that the HCN channel blocker ZD7288 remarkably decreased the percentage of apoptotic neurons and corrected the excessive autophagy induced by oxygen-glucose deprivation followed by reperfusion (OGD/R) in hippocampal HT22 neurons. Furthermore, in the OGD/R group, p-mTOR, p-ULK1 (Ser757), and p62 were significantly decreased, while p-ULK1 (Ser317), atg5, and beclin1 were remarkably increased. ZD7288 did not change the expression of p-ULK1 (Ser757), ULK1 (Ser317), p62, Beclin1, and atg5, which are involved in regulating autophagosome formation. Besides, we found that OGD/R induced a significant increase in Cathepsin D expression, but not LAMP-1. Treatment with ZD7288 at 10 μmol/L in the OGD/R group did not change the expression of cathepsin D and LAMP-1. However, chloroquine (CQ), which decreases autophagosome-lysosome fusion, eliminated the correction of excessive autophagy and neuroprotection by ZD7288. Besides, shRNA knockdown of HCN2 channels significantly reduced the accumulation of LC3-II and increased neuron survival in the OGD/R and transient global cerebral ischemia (TGCI) models, and CQ also eliminated the effects of HCN2-shRNA. Furthermore, we found that the percentage of LC3-positive puncta that co-localized with LAMP-1-positive lysosomes decreased in Con-shRNA-transfected HT22 neurons exposed to OGD/R or CQ. In HCN2-shRNA-transfected HT22 neurons, the percentage of LC3-positive puncta that co-localized with LAMP-1-positive lysosomes increased under OGD/R; however, the percentage was significantly decreased by the addition of CQ to HCN2-shRNA-transfected HT22 neurons. The present results demonstrated that blockade of HCN2 channels provides neuroprotection against OGD/R and TGCI by accelerating autophagic degradation attributable to the promotion of autophagosome and lysosome fusion.
Collapse
Affiliation(s)
- Cheng Chen
- Department of Pharmacology, School of Basic Medical Sciences, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China
| | - Li Liu
- Office of Academic Research, The Central Hospital of Wuhan, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China
| | - Ya-Qiao Shu
- Department of Pharmacology, School of Basic Medical Sciences, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China
| | - Ping Jing
- Department of Neurology, The Central Hospital of Wuhan, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China
| | - Yun Lu
- Department of Pharmacy, Zhongnan Hospital of Wuhan University, Wuhan, 430030, China
| | - Xiao-Xue Zhang
- Department of Clinical Laboratory, Wuhan PuAi Hospital, Wuhan, 430033, China
| | - Xian-Gang Zong
- Center for Integrated Protein Science and Zentrum für Pharmaforschung, Department Pharmazie, Ludwig-Maximilians-Universität München, 80539, Munich, Germany
| | - Lian-Jun Guo
- Department of Pharmacology, School of Basic Medical Sciences, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China.
- Key Laboratory of Drug Target Research and Pharmacodynamic Evaluation, Wuhan, 430030, China.
| | - Chang-Jun Li
- Department of Neurology, The Central Hospital of Wuhan, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China.
| |
Collapse
|
13
|
Epilepsy and Alzheimer’s Disease: Potential mechanisms for an association. Brain Res Bull 2020; 160:107-120. [DOI: 10.1016/j.brainresbull.2020.04.009] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2020] [Revised: 04/05/2020] [Accepted: 04/10/2020] [Indexed: 12/16/2022]
|
14
|
Kharouf Q, Phillips AM, Bleakley LE, Morrisroe E, Oyrer J, Jia L, Ludwig A, Jin L, Nicolazzo JA, Cerbai E, Romanelli MN, Petrou S, Reid CA. The hyperpolarization-activated cyclic nucleotide-gated 4 channel as a potential anti-seizure drug target. Br J Pharmacol 2020; 177:3712-3729. [PMID: 32364262 DOI: 10.1111/bph.15088] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2019] [Revised: 03/24/2020] [Accepted: 04/16/2020] [Indexed: 01/03/2023] Open
Abstract
BACKGROUND AND PURPOSE Hyperpolarization-activated cyclic nucleotide-gated (HCN) channels are encoded by four genes (HCN1-4) with distinct biophysical properties and functions within the brain. HCN4 channels activate slowly at robust hyperpolarizing potentials, making them more likely to be engaged during hyperexcitable neuronal network activity seen during seizures. HCN4 channels are also highly expressed in thalamic nuclei, a brain region implicated in seizure generalization. Here, we assessed the utility of targeting the HCN4 channel as an anti-seizure strategy using pharmacological and genetic approaches. EXPERIMENTAL APPROACH The impact of reducing HCN4 channel function on seizure susceptibility and neuronal network excitability was studied using an HCN4 channel preferring blocker (EC18) and a conditional brain specific HCN4 knockout mouse model. KEY RESULTS EC18 (10 mg·kg-1 ) and brain-specific HCN4 channel knockout reduced seizure susceptibility and proconvulsant-mediated cortical spiking recorded using electrocorticography, with minimal effects on other mouse behaviours. EC18 (10 μM) decreased neuronal network bursting in mouse cortical cultures. Importantly, EC18 was not protective against proconvulsant-mediated seizures in the conditional HCN4 channel knockout mouse and did not reduce bursting behaviour in AAV-HCN4 shRNA infected mouse cortical cultures. CONCLUSIONS AND IMPLICATIONS These data suggest the HCN4 channel as a potential pharmacologically relevant target for anti-seizure drugs that is likely to have a low side-effect liability in the CNS.
Collapse
Affiliation(s)
- Qays Kharouf
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, Victoria, Australia
| | - A Marie Phillips
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, Victoria, Australia.,School of Biosciences, University of Melbourne, Parkville, Victoria, Australia
| | - Lauren E Bleakley
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, Victoria, Australia
| | - Emma Morrisroe
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, Victoria, Australia
| | - Julia Oyrer
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, Victoria, Australia
| | - Linghan Jia
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, Victoria, Australia
| | - Andreas Ludwig
- Institut für Experimentelle und Klinische Pharmakologie und Toxikologie, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Liang Jin
- Drug Delivery, Disposition and Dynamics, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia
| | - Joseph A Nicolazzo
- Drug Delivery, Disposition and Dynamics, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia
| | - Elisabetta Cerbai
- Department of Neurosciences, Psychology, Drug Research and Child Health, (NEUROFARBA), University of Florence, Florence, Italy
| | - M Novella Romanelli
- Department of Neurosciences, Psychology, Drug Research and Child Health, (NEUROFARBA), University of Florence, Florence, Italy
| | - Steven Petrou
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, Victoria, Australia
| | - Christopher A Reid
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, Victoria, Australia
| |
Collapse
|
15
|
Lin W, Qin J, Ni G, Li Y, Xie H, Yu J, Li H, Sui L, Guo Q, Fang Z, Zhou L. Downregulation of hyperpolarization-activated cyclic nucleotide-gated channels (HCN) in the hippocampus of patients with medial temporal lobe epilepsy and hippocampal sclerosis (MTLE-HS). Hippocampus 2020; 30:1112-1126. [PMID: 32543742 DOI: 10.1002/hipo.23219] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2020] [Revised: 04/30/2020] [Accepted: 05/07/2020] [Indexed: 11/09/2022]
Abstract
Changes in the expression of HCN ion channels leading to changes in Ih function and neuronal excitability are considered to be possible mechanisms involved in epileptogenesis in kinds of human epilepsy. In previous animal studies of febrile seizures and temporal lobe epilepsy, changes in the expression of HCN1 and HCN2 channels at different time points and in different parts of the brain were not consistent, suggesting that transcriptional disorders involving HCNs play a crucial role in the epileptogenic process. Therefore, we aimed to assess the transcriptional regulation of HCN channels in Medial temporal lobe epilepsy with hippocampal sclerosis (MTLE-HS) patients. This study included eight nonhippocampal sclerosis patients and 40 MTLE-HS patients. The mRNA expression of HCN channels was evaluated by qRT-PCR, while the protein expression was quantitatively analyzed by Western blotting. The subcellular localization of HCN channels in the hippocampus was explored by immunofluorescence. We demonstrated that the mRNA and protein expression of HCN1 and HCN2 are downregulated in controls compared to that in MTLE-HS patients. In the hippocampal CA1/CA4 subregion and GCL, in addition to a large decrease in neurons, the expression of HCN1 and HCN2 on neuronal cell membranes was also downregulated in MTLE-HS patients. These findings suggest that the expression of HCN channels are downregulated in MTLE-HS, which indicates that the decline in HCN channels in the hippocampus during chronic epilepsy in MTLE-HS patients leads to the downregulation of Ih current density and function, thereby reducing the inhibitory effect and increasing neuronal excitability and eventually causing disturbances in the electrical activity of neurons.
Collapse
Affiliation(s)
- Wanrong Lin
- Department of Neurology, The Seventh Affiliated Hospital, Sun Yat-sen University, Shenzhen, China
| | - Jiaming Qin
- Department of Neurology, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, China
| | - Guanzhong Ni
- Department of Neurology, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, China
| | - Yinchao Li
- Department of Neurology, The Seventh Affiliated Hospital, Sun Yat-sen University, Shenzhen, China
| | - Haitao Xie
- Department of Epilepsy Center, Guangdong Provincial Hospital of Traditional Chinese Medicine, Guangzhou, China
| | - Jiabin Yu
- Department of Epilepsy Center, Guangdong Provincial Hospital of Traditional Chinese Medicine, Guangzhou, China
| | - Hainan Li
- Department of Neurosurgery, Guangdong Sanjiu Brain Hospital, Guangzhou, China
| | - Lisen Sui
- Department of Epilepsy Center, Guangdong Provincial Hospital of Traditional Chinese Medicine, Guangzhou, China
| | - Qiang Guo
- Department of Neurosurgery, Guangdong Sanjiu Brain Hospital, Guangzhou, China
| | - Ziyan Fang
- Department of Neurology, The Affiliated Brain Hospital of Guangzhou Medical University (Guangzhou Huiai Hospital), Guangzhou, China
| | - Liemin Zhou
- Department of Neurology, The Seventh Affiliated Hospital, Sun Yat-sen University, Shenzhen, China.,Department of Neurology, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, China
| |
Collapse
|
16
|
Carver CM, Hastings SD, Cook ME, Shapiro MS. Functional responses of the hippocampus to hyperexcitability depend on directed, neuron-specific KCNQ2 K + channel plasticity. Hippocampus 2019; 30:435-455. [PMID: 31621989 DOI: 10.1002/hipo.23163] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2019] [Revised: 07/24/2019] [Accepted: 08/30/2019] [Indexed: 12/14/2022]
Abstract
M-type (KCNQ2/3) K+ channels play dominant roles in regulation of active and passive neuronal discharge properties such as resting membrane potential, spike-frequency adaptation, and hyper-excitatory states. However, plasticity of M-channel expression and function in nongenetic forms of epileptogenesis are still not well understood. Using transgenic mice with an EGFP reporter to detect expression maps of KCNQ2 mRNA, we assayed hyperexcitability-induced alterations in KCNQ2 transcription across subregions of the hippocampus. Pilocarpine and pentylenetetrazol chemoconvulsant models of seizure induction were used, and brain tissue examined 48 hr later. We observed increases in KCNQ2 mRNA in CA1 and CA3 pyramidal neurons after chemoconvulsant-induced hyperexcitability at 48 hr, but no significant change was observed in dentate gyrus (DG) granule cells. Using chromogenic in situ hybridization assays, changes to KCNQ3 transcription were not detected after hyper-excitation challenge, but the results for KCNQ2 paralleled those using the KCNQ2-mRNA reporter mice. In mice 7 days after pilocarpine challenge, levels of KCNQ2 mRNA were similar in all regions to those from control mice. In brain-slice electrophysiology recordings, CA1 pyramidal neurons demonstrated increased M-current amplitudes 48 hr after hyperexcitability; however, there were no significant changes to DG granule cell M-current amplitude. Traumatic brain injury induced significantly greater KCNQ2 expression in the hippocampal hemisphere that was ipsilateral to the trauma. In vivo, after a secondary challenge with subconvulsant dose of pentylenetetrazole, control mice were susceptible to tonic-clonic seizures, whereas mice administered the M-channel opener retigabine were protected from such seizures. This study demonstrates that increased excitatory activity promotes KCNQ2 upregulation in the hippocampus in a cell-type specific manner. Such novel ion channel expressional plasticity may serve as a compensatory mechanism after a hyperexcitable event, at least in the short term. The upregulation described could be potentially leveraged in anticonvulsant enhancement of KCNQ2 channels as therapeutic target for preventing onset of epileptogenic seizures.
Collapse
Affiliation(s)
- Chase M Carver
- Department of Cellular and Integrative Physiology, University of Texas Health San Antonio, San Antonio, Texas
| | - Shayne D Hastings
- Department of Cellular and Integrative Physiology, University of Texas Health San Antonio, San Antonio, Texas
| | - Mileah E Cook
- Department of Cellular and Integrative Physiology, University of Texas Health San Antonio, San Antonio, Texas
| | - Mark S Shapiro
- Department of Cellular and Integrative Physiology, University of Texas Health San Antonio, San Antonio, Texas
| |
Collapse
|
17
|
Çarçak N, Ali I, Powell K, Zheng T, Onat F, O'Brien TJ. Ca
v
3.2 T‐type calcium channel mutation influences kindling‐induced thalamic neuronal firing patterns in Genetic Absence Epilepsy Rats From Strasbourg. Epilepsia 2019; 60:1378-1386. [DOI: 10.1111/epi.16076] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2019] [Revised: 05/21/2019] [Accepted: 05/22/2019] [Indexed: 01/30/2023]
Affiliation(s)
- Nihan Çarçak
- Department of Pharmacology Faculty of Pharmacy Istanbul University Istanbul Turkey
- Departments of Medicine and Neurology Royal Melbourne Hospital University of Melbourne Melbourne Victoria Australia
| | - Idrish Ali
- Departments of Medicine and Neurology Royal Melbourne Hospital University of Melbourne Melbourne Victoria Australia
- Departments of Neuroscience and Neurology Central Clinical School Alfred Health Monash University Clayton Victoria Australia
| | - Kim Powell
- Departments of Medicine and Neurology Royal Melbourne Hospital University of Melbourne Melbourne Victoria Australia
- Departments of Neuroscience and Neurology Central Clinical School Alfred Health Monash University Clayton Victoria Australia
| | - Thomas Zheng
- Departments of Medicine and Neurology Royal Melbourne Hospital University of Melbourne Melbourne Victoria Australia
| | - Filiz Onat
- Department of Pharmacology and Clinical Pharmacology Faculty of Medicine Marmara University Istanbul Turkey
- Marmara University Epilepsy Research Center Istanbul Turkey
| | - Terence J. O'Brien
- Departments of Medicine and Neurology Royal Melbourne Hospital University of Melbourne Melbourne Victoria Australia
- Departments of Neuroscience and Neurology Central Clinical School Alfred Health Monash University Clayton Victoria Australia
| |
Collapse
|
18
|
Ghotbeddin Z, Heysieattalab S, Borjkhani M, Mirnajafi-Zadeh J, Semnanian S, Hosseinmardi N, Janahmadi M. Ca 2+ Channels Involvement in Low-Frequency Stimulation-Mediated Suppression of Intrinsic Excitability of Hippocampal CA1 Pyramidal Cells in a Rat Amygdala Kindling Model. Neuroscience 2019; 406:234-248. [PMID: 30885638 DOI: 10.1016/j.neuroscience.2019.03.012] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2018] [Revised: 03/04/2019] [Accepted: 03/05/2019] [Indexed: 12/26/2022]
Abstract
Low-frequency stimulation has demonstrated promising seizure suppression in animal models of epilepsy, while the mechanism of the effect is still debated. Changes in intrinsic properties have been recognized as a prominent pathophysiologically relevant feature of numerous neurological disorders including epilepsy. Here, it was evaluated whether LFS can preserve the intrinsic neuronal electrophysiological properties in a rat model of epilepsy, focusing on the possible involvement of voltage-gated Ca2+ channels. The amygdala kindling model was induced by 3 s monophasic square wave pulses (50 Hz, 1 ms duration, 12times/day at 5 min intervals). Both LFS alone and kindled plus LFS (KLFS) groups received four packages of LFS (each consisting of 200 monophasic square pulses, 0.1 ms pulse duration at 1 Hz with the after discharge threshold intensity), which in KLFS rats was applied immediately after kindling induction. Whole-cell patch-clamp recordings were made in the presence of fast synaptic blockers 24 h after the last kindling stimulations or following kindling stimulations plus LFS application. In the KLFS group, both the rebound excitation and kindling-induced intrinsic hyperexcitability were decreased, associated with a regular intrinsic firing as indicated by a lower coefficient of variation. The amplitude of afterdepolarization (ADP) and its area under the curve were both decreased in the KLFS group compared to the kindled group. LFS prevented the increasing effect of kindling on Ca2+ currents in the KLFS group. Findings provided evidence for a novel form of epileptiform activity suppression by LFS in the presence of synaptic blockade possibly by decreasing Ca2+ currents.
Collapse
Affiliation(s)
- Zohreh Ghotbeddin
- Department of Physiology, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran; Department of Physiology, Faculty of Veterinary Medicine, Shahid Chamran University of Ahvaz, Ahvaz, Iran; Stem Cell and Transgenic Technology Research Center, Shahid Chamran University of Ahvaz, Ahvaz, Iran
| | | | - Mehdi Borjkhani
- Department of Electrical Engineering, Urmia University of Technology, Urmia, Iran
| | - Javad Mirnajafi-Zadeh
- Department of Physiology, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran
| | - Saeed Semnanian
- Department of Physiology, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran
| | - Narges Hosseinmardi
- Neuroscience Research Center and Department of Physiology, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Mahyar Janahmadi
- Neuroscience Research Center and Department of Physiology, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
| |
Collapse
|
19
|
Arnold EC, McMurray C, Gray R, Johnston D. Epilepsy-Induced Reduction in HCN Channel Expression Contributes to an Increased Excitability in Dorsal, But Not Ventral, Hippocampal CA1 Neurons. eNeuro 2019; 6:ENEURO.0036-19.2019. [PMID: 30957013 PMCID: PMC6449163 DOI: 10.1523/eneuro.0036-19.2019] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2019] [Accepted: 03/05/2019] [Indexed: 12/31/2022] Open
Abstract
CA1 neurons in epileptic animals are vulnerable to selective changes in ion channel expression, called acquired channelopathies, which can increase the excitability of a neuron. Under normal conditions there is a gradient of ion channel expression and intrinsic excitability along the longitudinal, dorsoventral axis of hippocampal area CA1 of the rodent. Many of these channels, including M-channels, GIRK channels and HCN channels, all have dorsoventral expression gradients that might be altered in rodent models of epilepsy. Here, we show that the excitability of dorsal, but not ventral CA1 neurons, had an increased firing rate, reduced interspike interval (ISI) and increased input resistance in a status epilepticus (SE) model of temporal lobe epilepsy (TLE). As a result, the excitability of CA1 neurons became uniform across the dorsoventral axis of the rat hippocampus post-SE. Using current clamp recordings with pharmacology and immunohistochemistry, we demonstrate that the expression of HCN channels was downregulated in the dorsal CA1 region post-SE, while the expression of M and GIRK channels were unchanged. We did not find this acquired channelopathy in ventral CA1 neurons post-SE. Our results suggest that the excitability of dorsal CA1 neurons post-SE increase to resemble the intrinsic properties of ventral CA1 neurons, which likely makes the hippocampal circuit more permissible to seizures, and contributes to the cognitive impairments associated with chronic epilepsy.
Collapse
Affiliation(s)
- Elizabeth C. Arnold
- Institute for Neuroscience, University of Texas at Austin, Austin, TX 78712
- Center for Learning and Memory, University of Texas at Austin, Austin, TX 78712
| | - Calli McMurray
- Center for Learning and Memory, University of Texas at Austin, Austin, TX 78712
| | - Richard Gray
- Center for Learning and Memory, University of Texas at Austin, Austin, TX 78712
| | - Daniel Johnston
- Institute for Neuroscience, University of Texas at Austin, Austin, TX 78712
- Center for Learning and Memory, University of Texas at Austin, Austin, TX 78712
| |
Collapse
|
20
|
Lehnhoff J, Strauss U, Wierschke S, Grosser S, Pollali E, Schneider UC, Holtkamp M, Dehnicke C, Deisz RA. The anticonvulsant lamotrigine enhances Ih in layer 2/3 neocortical pyramidal neurons of patients with pharmacoresistant epilepsy. Neuropharmacology 2019; 144:58-69. [DOI: 10.1016/j.neuropharm.2018.10.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2017] [Revised: 09/19/2018] [Accepted: 10/05/2018] [Indexed: 11/29/2022]
|
21
|
Xiao K, Sun Z, Jin X, Ma W, Song Y, Lai S, Chen Q, Fan M, Zhang J, Yue W, Huang Z. ERG3 potassium channel-mediated suppression of neuronal intrinsic excitability and prevention of seizure generation in mice. J Physiol 2018; 596:4729-4752. [PMID: 30016551 DOI: 10.1113/jp275970] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2018] [Accepted: 07/05/2018] [Indexed: 12/15/2022] Open
Abstract
KEY POINTS ERG3 channels have a high expression level in the central nervous system. Knockdown of ERG3 channels enhances neuronal intrinsic excitability (caused by decreased fast afterhyperpolarization, shortened delay time to the generation of an action potential and enhanced summation of somatic excitatory postsynaptic potentials) in hippocampal CA1 pyramidal neurons and dentate gyrus granule cells. The expression of ERG3 protein is reduced in human and mouse hippocampal epileptogenic foci. Knockdown of ERG3 channels in hippocampus enhanced seizure susceptibility, while mice treated with the ERG channel activator NS-1643 were less prone to epileptogenesis. The results provide strong evidence that ERG3 channels have a crucial role in the regulation of neuronal intrinsic excitability in hippocampal CA1 pyramidal neurons and dentate gyrus granule cells and are critically involved in the onset and development of epilepsy. ABSTRACT The input-output relationship of neuronal networks depends heavily on the intrinsic properties of their neuronal elements. Profound changes in intrinsic properties have been observed in various physiological and pathological processes, such as learning, memory and epilepsy. However, the cellular and molecular mechanisms underlying acquired changes in intrinsic excitability are still not fully understood. Here, we demonstrate that ERG3 channels are critically involved in the regulation of intrinsic excitability in hippocampal CA1 pyramidal neurons and dentate gyrus granule cells. Knock-down of ERG3 channels significantly increases neuronal intrinsic excitability, which is mainly caused by decreased fast afterhyperpolarization, shortened delay time to the generation of an action potential and enhanced summation of somatic excitatory postsynaptic potentials. Interestingly, the expression level of ERG3 protein is significantly reduced in human and mouse brain tissues with temporal lobe epilepsy. Moreover, ERG3 channel knockdown in hippocampus significantly enhanced seizure susceptibility, while mice treated with the ERG channel activator NS-1643 were less prone to epileptogenesis. Taken together, our results suggest ERG3 channels play an important role in determining the excitability of hippocampal neurons and dysregulation of these channels may be involved in the generation of epilepsy. ERG3 channels may thus be a novel therapeutic target for the prevention of epilepsy.
Collapse
Affiliation(s)
- Kuo Xiao
- State Key Laboratory of Natural and Biomimetic Drugs, Department of Molecular and Cellular Pharmacology, School of Pharmaceutical Sciences, Peking University Health Science Center, Beijing, 100191, China
| | - Zhiming Sun
- State Key Laboratory of Natural and Biomimetic Drugs, Department of Molecular and Cellular Pharmacology, School of Pharmaceutical Sciences, Peking University Health Science Center, Beijing, 100191, China
| | - Xueqin Jin
- State Key Laboratory of Natural and Biomimetic Drugs, Department of Molecular and Cellular Pharmacology, School of Pharmaceutical Sciences, Peking University Health Science Center, Beijing, 100191, China
| | - Weining Ma
- Department of Neurology, Shengjing Hospital affiliated to China Medical University, Shenyang, 110000, China
| | - Yan Song
- State Key Laboratory of Natural and Biomimetic Drugs, Department of Molecular and Cellular Pharmacology, School of Pharmaceutical Sciences, Peking University Health Science Center, Beijing, 100191, China
| | - Shirong Lai
- State Key Laboratory of Natural and Biomimetic Drugs, Department of Molecular and Cellular Pharmacology, School of Pharmaceutical Sciences, Peking University Health Science Center, Beijing, 100191, China
| | - Qian Chen
- State Key Laboratory of Natural and Biomimetic Drugs, Department of Molecular and Cellular Pharmacology, School of Pharmaceutical Sciences, Peking University Health Science Center, Beijing, 100191, China
| | - Minghua Fan
- State Key Laboratory of Natural and Biomimetic Drugs, Department of Molecular and Cellular Pharmacology, School of Pharmaceutical Sciences, Peking University Health Science Center, Beijing, 100191, China
| | - Jingliang Zhang
- State Key Laboratory of Natural and Biomimetic Drugs, Department of Molecular and Cellular Pharmacology, School of Pharmaceutical Sciences, Peking University Health Science Center, Beijing, 100191, China
| | - Weihua Yue
- Peking University Sixth Hospital (Institute of Mental Health), Beijing, 100191, China.,National Clinical Research Center for Mental Disorders & Key Laboratory of Mental Health, Ministry of Health (Peking University), Beijing, 100191, China
| | - Zhuo Huang
- State Key Laboratory of Natural and Biomimetic Drugs, Department of Molecular and Cellular Pharmacology, School of Pharmaceutical Sciences, Peking University Health Science Center, Beijing, 100191, China.,Key Laboratory for Neuroscience, Ministry of Education, Beijing, 100191, China
| |
Collapse
|
22
|
PSD-95-nNOS Coupling Regulates Contextual Fear Extinction in the Dorsal CA3. Sci Rep 2018; 8:12775. [PMID: 30143658 PMCID: PMC6109109 DOI: 10.1038/s41598-018-30899-4] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2017] [Accepted: 04/17/2018] [Indexed: 12/16/2022] Open
Abstract
Fear extinction depends on N-methyl-D-aspartate glutamate receptors (NMDARs) and brain-derived neurotrophic factor (BDNF) activation in the limbic system. However, postsynaptic density-95 (PSD-95) and neuronal nitric oxide synthase (nNOS) coupling, the downstream signaling of NMDARs activation, obstructs the BDNF signaling transduction. Thus, we wondered distinct roles of NMDAR activation and PSD-95-nNOS coupling on fear extinction. To explore the mechanisms, we detected protein-protein interaction using coimmunoprecipitation and measured protein expression by western blot. Contextual fear extinction induced a shift from PSD-95-nNOS to PSD-95-TrkB association in the dorsal hippocampus and c-Fos expression in the dorsal CA3. Disrupting PSD-95-nNOS coupling in the dorsal CA3 up-regulated phosphorylation of extracellular signal-regulates kinase (ERK) and BDNF, enhanced the association of BDNF-TrkB signaling with PSD-95, and promoted contextual fear extinction. Conversely, blocking NMDARs in the dorsal CA3 down-regulated BDNF expression and hindered contextual fear extinction. NMDARs activation and PSD-95-nNOS coupling play different roles in modulating contextual fear extinction in the hippocampus. Because inhibitors of PSD-95-nNOS interaction produce antidepressant and anxiolytic effect without NMDAR-induced side effects, PSD-95-nNOS could be a valuable target for PTSD treatment.
Collapse
|
23
|
Bonzanni M, DiFrancesco JC, Milanesi R, Campostrini G, Castellotti B, Bucchi A, Baruscotti M, Ferrarese C, Franceschetti S, Canafoglia L, Ragona F, Freri E, Labate A, Gambardella A, Costa C, Rivolta I, Gellera C, Granata T, Barbuti A, DiFrancesco D. A novel de novo HCN1 loss-of-function mutation in genetic generalized epilepsy causing increased neuronal excitability. Neurobiol Dis 2018; 118:55-63. [PMID: 29936235 DOI: 10.1016/j.nbd.2018.06.012] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2018] [Revised: 06/11/2018] [Accepted: 06/15/2018] [Indexed: 11/26/2022] Open
Abstract
The causes of genetic epilepsies are unknown in the majority of patients. HCN ion channels have a widespread expression in neurons and increasing evidence demonstrates their functional involvement in human epilepsies. Among the four known isoforms, HCN1 is the most expressed in the neocortex and hippocampus and de novo HCN1 point mutations have been recently associated with early infantile epileptic encephalopathy. So far, HCN1 mutations have not been reported in patients with idiopathic epilepsy. Using a Next Generation Sequencing approach, we identified the de novo heterozygous p.Leu157Val (c.469C > G) novel mutation in HCN1 in an adult male patient affected by genetic generalized epilepsy (GGE), with normal cognitive development. Electrophysiological analysis in heterologous expression model (CHO cells) and in neurons revealed that L157V is a loss-of-function, dominant negative mutation causing reduced HCN1 contribution to net inward current and responsible for an increased neuronal firing rate and excitability, potentially predisposing to epilepsy. These data represent the first evidence that autosomal dominant missense mutations of HCN1 can also be involved in GGE, without the characteristics of epileptic encephalopathy reported previously. It will be important to include HCN1 screening in patients with GGE, in order to extend the knowledge of the genetic causes of idiopathic epilepsies, thus paving the way for the identification of innovative therapeutic strategies.
Collapse
Affiliation(s)
- Mattia Bonzanni
- Dept. of Biosciences, The PaceLab, University of Milano, Milano, Italy
| | - Jacopo C DiFrancesco
- Clinical Neurophysiology and Epilepsy Center, "C. Besta" Neurological Institute, Milano, Italy; Dept. of Neurology, San Gerardo Hospital, Laboratory of Neurobiology, Milan Center for Neuroscience, University of Milano-Bicocca, Monza, Italy.
| | | | | | - Barbara Castellotti
- Unit of Genetics of Neurodegenerative and Metabolic Diseases, "C. Besta" Neurological Institute, Milano, Italy
| | - Annalisa Bucchi
- Dept. of Biosciences, The PaceLab, University of Milano, Milano, Italy
| | - Mirko Baruscotti
- Dept. of Biosciences, The PaceLab, University of Milano, Milano, Italy
| | - Carlo Ferrarese
- Dept. of Neurology, San Gerardo Hospital, Laboratory of Neurobiology, Milan Center for Neuroscience, University of Milano-Bicocca, Monza, Italy
| | - Silvana Franceschetti
- Clinical Neurophysiology and Epilepsy Center, "C. Besta" Neurological Institute, Milano, Italy
| | - Laura Canafoglia
- Clinical Neurophysiology and Epilepsy Center, "C. Besta" Neurological Institute, Milano, Italy
| | - Francesca Ragona
- Dept. of Pediatric Neuroscience, "C. Besta" Neurological Institute, Milano, Italy
| | - Elena Freri
- Dept. of Pediatric Neuroscience, "C. Besta" Neurological Institute, Milano, Italy
| | - Angelo Labate
- Institute of Neurology, University "Magna Graecia", Catanzaro, Italy
| | | | - Cinzia Costa
- Neurology Unit, Department of Medicine, University of Perugia, Ospedale S. Maria della Misericordia, Perugia, Italy
| | - Ilaria Rivolta
- School of Medicine and Surgery, Milan Center for Neuroscience and Nanomedicine Center, University of Milano-Bicocca, Monza, Italy
| | - Cinzia Gellera
- Unit of Genetics of Neurodegenerative and Metabolic Diseases, "C. Besta" Neurological Institute, Milano, Italy
| | - Tiziana Granata
- Dept. of Pediatric Neuroscience, "C. Besta" Neurological Institute, Milano, Italy
| | - Andrea Barbuti
- Dept. of Biosciences, The PaceLab, University of Milano, Milano, Italy.
| | - Dario DiFrancesco
- Dept. of Biosciences, The PaceLab, University of Milano, Milano, Italy
| |
Collapse
|
24
|
Smirnova EY, Amakhin DV, Malkin SL, Chizhov AV, Zaitsev AV. Acute Changes in Electrophysiological Properties of Cortical Regular-Spiking Cells Following Seizures in a Rat Lithium–Pilocarpine Model. Neuroscience 2018; 379:202-215. [DOI: 10.1016/j.neuroscience.2018.03.020] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2017] [Revised: 03/14/2018] [Accepted: 03/15/2018] [Indexed: 11/26/2022]
|
25
|
Bertoglio D, Amhaoul H, Van Eetveldt A, Houbrechts R, Van De Vijver S, Ali I, Dedeurwaerdere S. Kainic Acid-Induced Post-Status Epilepticus Models of Temporal Lobe Epilepsy with Diverging Seizure Phenotype and Neuropathology. Front Neurol 2017; 8:588. [PMID: 29163349 PMCID: PMC5681498 DOI: 10.3389/fneur.2017.00588] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2017] [Accepted: 10/20/2017] [Indexed: 12/28/2022] Open
Abstract
The aim of epilepsy models is to investigate disease ontogenesis and therapeutic interventions in a consistent and prospective manner. The kainic acid-induced status epilepticus (KASE) rat model is a widely used, well-validated model for temporal lobe epilepsy (TLE). As we noted significant variability within the model between labs potentially related to the rat strain used, we aimed to describe two variants of this model with diverging seizure phenotype and neuropathology. In addition, we evaluated two different protocols to induce status epilepticus (SE). Wistar Han (Charles River, France) and Sprague-Dawley (Harlan, The Netherlands) rats were subjected to KASE using the Hellier kainic acid (KA) and a modified injection scheme. Duration of SE and latent phase were characterized by video-electroencephalography (vEEG) in a subgroup of animals, while animals were sacrificed 1 week (subacute phase) and 12 weeks (chronic phase) post-SE. In the 12 weeks post-SE groups, seizures were monitored with vEEG. Neuronal loss (neuronal nuclei), microglial activation (OX-42 and translocator protein), and neurodegeneration (Fluorojade C) were assessed. First, the Hellier protocol caused very high mortality in WH/CR rats compared to SD/H animals. The modified protocol resulted in a similar SE severity for WH/CR and SD/H rats, but effectively improved survival rates. The latent phase was significantly shorter (p < 0.0001) in SD/H (median 8.3 days) animals compared to WH/CR (median 15.4 days). During the chronic phase, SD/H rats had more seizures/day compared to WH/CR animals (p < 0.01). However, neuronal degeneration and cell loss were overall more extensive in WH/CR than in SD/H rats; microglia activation was similar between the two strains 1 week post-SE, but higher in WH/CR rats 12 weeks post-SE. These neuropathological differences may be more related to the distinct neurotoxic effects of KA in the two rat strains than being the outcome of seizure burden itself. The divergences in disease progression and seizure outcome, in addition to the histopathological dissimilarities, further substantiate the existence of strain differences for the KASE rat model of TLE.
Collapse
Affiliation(s)
- Daniele Bertoglio
- Department of Translational Neurosciences, University of Antwerp, Antwerp, Belgium
| | - Halima Amhaoul
- Department of Translational Neurosciences, University of Antwerp, Antwerp, Belgium
| | - Annemie Van Eetveldt
- Department of Translational Neurosciences, University of Antwerp, Antwerp, Belgium
| | - Ruben Houbrechts
- Department of Translational Neurosciences, University of Antwerp, Antwerp, Belgium
| | | | - Idrish Ali
- Department of Translational Neurosciences, University of Antwerp, Antwerp, Belgium
| | | |
Collapse
|
26
|
Bhandare AM, Kapoor K, Powell KL, Braine E, Casillas-Espinosa P, O'Brien TJ, Farnham MM, Pilowsky PM. Inhibition of microglial activation with minocycline at the intrathecal level attenuates sympathoexcitatory and proarrhythmogenic changes in rats with chronic temporal lobe epilepsy. Neuroscience 2017; 350:23-38. [DOI: 10.1016/j.neuroscience.2017.03.012] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2016] [Revised: 03/02/2017] [Accepted: 03/07/2017] [Indexed: 12/19/2022]
|
27
|
Albertson AJ, Bohannon AS, Hablitz JJ. HCN Channel Modulation of Synaptic Integration in GABAergic Interneurons in Malformed Rat Neocortex. Front Cell Neurosci 2017; 11:109. [PMID: 28469560 PMCID: PMC5396479 DOI: 10.3389/fncel.2017.00109] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2017] [Accepted: 03/30/2017] [Indexed: 12/02/2022] Open
Abstract
Cortical malformations are often associated with pharmaco-resistant epilepsy. Alterations in hyperpolarization-activated, cyclic nucleotide-gated, non-specific cation (HCN) channels have been shown to contribute to malformation associated hyperexcitability. We have recently demonstrated that expression of HCN channels and Ih current amplitudes are reduced in layer (L) 5 pyramidal neurons of rats with freeze lesion induced malformations. These changes were associated with an increased EPSP temporal summation. Here, we examine the effects of HCN channel inhibition on synaptic responses in fast spiking, presumptive basket cells and accommodating, presumptive Martinotti, GABAergic interneurons in slices from freeze lesioned animals. In control animals, fast spiking cells showed small sag responses which were reduced by the HCN channel antagonist ZD7288. Fast spiking cells in lesioned animals showed absent or reduced sag responses. The amplitude of single evoked EPSPs in fast spiking cells in the control group was not affected by HCN channel inhibition with ZD7288. EPSP ratios during short stimulus trains at 25 Hz were not significantly different between control and lesion groups. ZD7288 produced an increase in EPSP ratios in the control but not lesion groups. Under voltage clamp conditions, ZD7288 did not affect EPSC ratios. In the control group, accommodating interneurons showed robust sag responses which were significantly reduced by ZD7288. HCN channel inhibition increased EPSP ratios and area in controls but not the lesioned group. The results indicate that HCN channels differentially modulate EPSPs in different classes of GABAergic interneurons and that this control is reduced in malformed rat neocortex.
Collapse
Affiliation(s)
- Asher J Albertson
- Department of Neurobiology, University of Alabama at BirminghamBirmingham, AL, USA
| | - Andrew S Bohannon
- Department of Neurobiology, University of Alabama at BirminghamBirmingham, AL, USA
| | - John J Hablitz
- Department of Neurobiology, University of Alabama at BirminghamBirmingham, AL, USA
| |
Collapse
|
28
|
Bednarczyk J, Dębski KJ, Bot AM, Lukasiuk K. MBD3 expression and DNA binding patterns are altered in a rat model of temporal lobe epilepsy. Sci Rep 2016; 6:33736. [PMID: 27650712 PMCID: PMC5030630 DOI: 10.1038/srep33736] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2015] [Accepted: 09/02/2016] [Indexed: 12/18/2022] Open
Abstract
The aim of the present study was to examine involvement of MBD3 (methyl-CpG-binding domain protein 3), a protein involved in reading DNA methylation patterns, in epileptogenesis and epilepsy. We used a well-characterized rat model of temporal lobe epilepsy that is triggered by status epilepticus, evoked by electrical stimulation of the amygdala. Stimulated and sham-operated animals were sacrificed 14 days after stimulation. We found that MBD3 transcript was present in neurons, oligodendrocytes, and astrocytes in both control and epileptic animals. We detected the nuclear localization of MBD3 protein in neurons, mature oligodendrocytes, and a subpopulation of astrocytes but not in microglia. Amygdala stimulation significantly increased the level of MBD3 immunofluorescence. Immunoprecipitation followed by mass spectrometry and Western blot revealed that MBD3 in the adult brain assembles the NuRD complex, which also contains MTA2, HDAC2, and GATAD2B. Using chromatin immunoprecipitation combined with deep sequencing, we observed differences in the occupancy of DNA regions by MBD3 protein between control and stimulated animals. This was not followed by subsequent changes in the mRNA expression levels of selected MBD3 targets. Our data demonstrate for the first time alterations in the MBD3 expression and DNA occupancy in the experimental model of epilepsy.
Collapse
Affiliation(s)
- Joanna Bednarczyk
- Laboratory of Epileptogenesis, Department of Molecular and Cellular Neurobiology, Nencki Institute of Experimental Biology of Polish Academy of Sciences, Warsaw, Poland
| | - Konrad J. Dębski
- Laboratory of Epileptogenesis, Department of Molecular and Cellular Neurobiology, Nencki Institute of Experimental Biology of Polish Academy of Sciences, Warsaw, Poland
- Laboratory of Bioinformatics, Neurobiology Center, Nencki Institute of Experimental Biology of Polish Academy of Sciences, Warsaw, Poland
| | - Anna M. Bot
- Laboratory of Epileptogenesis, Department of Molecular and Cellular Neurobiology, Nencki Institute of Experimental Biology of Polish Academy of Sciences, Warsaw, Poland
| | - Katarzyna Lukasiuk
- Laboratory of Epileptogenesis, Department of Molecular and Cellular Neurobiology, Nencki Institute of Experimental Biology of Polish Academy of Sciences, Warsaw, Poland
| |
Collapse
|
29
|
Ravindran K, Powell KL, Todaro M, O'Brien TJ. The pathophysiology of cardiac dysfunction in epilepsy. Epilepsy Res 2016; 127:19-29. [PMID: 27544485 DOI: 10.1016/j.eplepsyres.2016.08.007] [Citation(s) in RCA: 65] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2016] [Revised: 08/07/2016] [Accepted: 08/10/2016] [Indexed: 11/15/2022]
Abstract
Alterations in cardiac electrophysiology are an established consequence of long-standing drug resistant epilepsy. Patients with chronic epilepsy display abnormalities in both sinoatrial node pacemaker current as well as ventricular repolarizing current that places them at a greater risk of developing life-threatening cardiac arrhythmias. The development of cardiac arrhythmias secondary to drug resistant epilepsy is believed to be a key mechanism underlying the phenomenon of Sudden Unexpected Death in EPilepsy (SUDEP). Though an increasing amount of studies examining both animal models and human patients have provided evidence that chronic epilepsy can detrimentally affect cardiac function, the underlying pathophysiology remains unclear. Recent work has shown the expression of several key cardiac ion channels to be altered in animal models of genetic and acquired epilepsies. This has led to the currently held paradigm that cardiac ion channel expression may be secondarily altered as a consequence of seizure activity-resulting in electrophysiological cardiac dysfunction. Furthermore, cortical autonomic dysfunction - resulting from seizure activity-has also been suggested to play a role, whereby seizure activity may indirectly influence cardiac function via altering centrally-mediated autonomic output to the heart. In this review, we discuss various cardiac dysrhythmias associated with seizure events-including tachycardia, bradycardia and QT prolongation, both ictally and inter-ictally, as well as the role of the autonomic nervous system. We further discuss key ion channels expressed in both the heart and the brain that have been shown to be altered in epilepsy and may be responsible for the development of cardiac dysrhythmias secondary to chronic epilepsy.
Collapse
Affiliation(s)
- Krishnan Ravindran
- Department of Medicine, The University of Melbourne, Royal Melbourne Hospital, Parkville, VIC, Australia.
| | - Kim L Powell
- Department of Medicine, The University of Melbourne, Royal Melbourne Hospital, Parkville, VIC, Australia
| | - Marian Todaro
- Department of Medicine, The University of Melbourne, Royal Melbourne Hospital, Parkville, VIC, Australia
| | - Terence J O'Brien
- Department of Medicine, The University of Melbourne, Royal Melbourne Hospital, Parkville, VIC, Australia.
| |
Collapse
|
30
|
Lu Y, Li CJ, Chen C, Luo P, Zhou M, Li C, Xu XL, Lu Q, He Z, Guo LJ. Activation of GABAB2 subunits alleviates chronic cerebral hypoperfusion-induced anxiety-like behaviours: A role for BDNF signalling and Kir3 channels. Neuropharmacology 2016; 110:308-321. [PMID: 27515806 DOI: 10.1016/j.neuropharm.2016.08.007] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2015] [Revised: 07/30/2016] [Accepted: 08/06/2016] [Indexed: 12/15/2022]
Abstract
Anxiety is an affective disorder that is commonly observed after irreversible brain damage induced by cerebral ischemia and can delay the physical and cognitive recovery, which affects the quality of life of both the patient and family members. However, anxiety after ischemia has received less attention, and mechanisms underlying anxiety-like behaviours induced by chronic cerebral ischemia are under-investigated. In the present study, the chronic cerebral hypoperfusion model was established by the permanent occlusion of the bilateral common carotid arteries (two-vessel occlusion, 2VO) in rats, and anxiety-related behaviours were evaluated. Results indicated that 2VO induced obvious anxiety-like behaviours; the surface expressions of GABAB2 subunits were down-regulated; Brain derived neurotrophic factor (BDNF), tyrosine kinase B (TrkB) and neural cell adhesion molecule (NCAM) were reduced; Meanwhile, the surface expressions of G protein-activated inwardly rectifying potassium (GIRK, Kir3) channels were up-regulated in hippocampal CA1 in 2VO rats. Baclofen, a GABAB receptor agonist, significantly ameliorated the anxiety-like behaviours. It also improved the down-regulation of GABAB2 surface expressions, restored the levels of BDNF, TrkB and NCAM, and reversed the increased surface expressions of Kir3 in hippocampal CA1 in 2VO rats. However, the effects of baclofen were absent in shRNA-GABAB2 infected 2VO rats. These results suggested that activation of GABAB2 subunits could improve BDNF signalling and reverse Kir3 channel surface expressions in hippocampal CA1, which may alleviate the anxiety-like behaviours in rats with chronic cerebral hypoperfusion.
Collapse
Affiliation(s)
- Yun Lu
- Department of Pharmacology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
| | - Chang-Jun Li
- Neurology Department, Tongji Medical College, Huazhong University of Science and Technology, The Central Hospital of Wuhan, Wuhan 430030, China
| | - Cheng Chen
- Department of Pharmacology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
| | - Pan Luo
- Department of Pharmacology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
| | - Mei Zhou
- Department of Pharmacology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
| | - Cai Li
- Department of Pharmacology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
| | - Xu-Lin Xu
- Department of Pharmacology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China; Institute of Brain Research, Huazhong University of Science and Technology, Wuhan 430030, China
| | - Qing Lu
- Department of Pharmacology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China; Institute of Brain Research, Huazhong University of Science and Technology, Wuhan 430030, China
| | - Zhi He
- Department of Neuropsychopharmacology, Medical School of China Three Gorges University, Yichang 443002, China.
| | - Lian-Jun Guo
- Department of Pharmacology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China; Institute of Brain Research, Huazhong University of Science and Technology, Wuhan 430030, China.
| |
Collapse
|
31
|
Liu SJ, Zheng P, Wright DK, Dezsi G, Braine E, Nguyen T, Corcoran NM, Johnston LA, Hovens CM, Mayo JN, Hudson M, Shultz SR, Jones NC, O'Brien TJ. Sodium selenate retards epileptogenesis in acquired epilepsy models reversing changes in protein phosphatase 2A and hyperphosphorylated tau. Brain 2016; 139:1919-38. [PMID: 27289302 DOI: 10.1093/brain/aww116] [Citation(s) in RCA: 93] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2015] [Accepted: 04/11/2016] [Indexed: 11/14/2022] Open
Abstract
There are no treatments in clinical practice known to mitigate the neurobiological processes that convert a healthy brain into an epileptic one, a phenomenon known as epileptogenesis. Downregulation of protein phosphatase 2A, a protein that causes the hyperphosphorylation of tau, is implicated in neurodegenerative diseases commonly associated with epilepsy, such as Alzheimer's disease and traumatic brain injury. Here we used the protein phosphatase 2A activator sodium selenate to investigate the role of protein phosphatase 2A in three different rat models of epileptogenesis: amygdala kindling, post-kainic acid status epilepticus, and post-traumatic epilepsy. Protein phosphatase 2A activity was decreased, and tau phosphorylation increased, in epileptogenic brain regions in all three models. Continuous sodium selenate treatment mitigated epileptogenesis and prevented the biochemical abnormalities, effects which persisted after drug withdrawal. Our studies indicate that limbic epileptogenesis is associated with downregulation of protein phosphatase 2A and the hyperphosphorylation of tau, and that targeting this mechanism with sodium selenate is a potential anti-epileptogenic therapy.
Collapse
Affiliation(s)
- Shi-Jie Liu
- 1 Department of Medicine, Melbourne Brain Centre, The Royal Melbourne Hospital, The University of Melbourne, Parkville, VIC, Australia
| | - Ping Zheng
- 1 Department of Medicine, Melbourne Brain Centre, The Royal Melbourne Hospital, The University of Melbourne, Parkville, VIC, Australia
| | - David K Wright
- 2 The Florey Institute of Neuroscience and Mental Health, Parkville, VIC, Australia 3 Department of Anatomy and Neuroscience, The University of Melbourne, Parkville, VIC, Australia
| | - Gabi Dezsi
- 1 Department of Medicine, Melbourne Brain Centre, The Royal Melbourne Hospital, The University of Melbourne, Parkville, VIC, Australia
| | - Emma Braine
- 1 Department of Medicine, Melbourne Brain Centre, The Royal Melbourne Hospital, The University of Melbourne, Parkville, VIC, Australia
| | - Thanh Nguyen
- 4 Department of Surgery, Melbourne Brain Centre, The Royal Melbourne Hospital, The University of Melbourne, Parkville, VIC, Australia
| | - Niall M Corcoran
- 4 Department of Surgery, Melbourne Brain Centre, The Royal Melbourne Hospital, The University of Melbourne, Parkville, VIC, Australia
| | - Leigh A Johnston
- 2 The Florey Institute of Neuroscience and Mental Health, Parkville, VIC, Australia 5 Department of Electrical and Electronic Engineering, The University of Melbourne, Parkville, VIC, Australia
| | - Christopher M Hovens
- 4 Department of Surgery, Melbourne Brain Centre, The Royal Melbourne Hospital, The University of Melbourne, Parkville, VIC, Australia
| | - Jamie N Mayo
- 1 Department of Medicine, Melbourne Brain Centre, The Royal Melbourne Hospital, The University of Melbourne, Parkville, VIC, Australia
| | - Matthew Hudson
- 1 Department of Medicine, Melbourne Brain Centre, The Royal Melbourne Hospital, The University of Melbourne, Parkville, VIC, Australia
| | - Sandy R Shultz
- 1 Department of Medicine, Melbourne Brain Centre, The Royal Melbourne Hospital, The University of Melbourne, Parkville, VIC, Australia
| | - Nigel C Jones
- 1 Department of Medicine, Melbourne Brain Centre, The Royal Melbourne Hospital, The University of Melbourne, Parkville, VIC, Australia
| | - Terence J O'Brien
- 1 Department of Medicine, Melbourne Brain Centre, The Royal Melbourne Hospital, The University of Melbourne, Parkville, VIC, Australia 6 Department of Neurology, Melbourne Brain Centre, The Royal Melbourne Hospital, The University of Melbourne, Parkville, VIC, Australia
| |
Collapse
|
32
|
Brennan GP, Baram TZ, Poolos NP. Hyperpolarization-Activated Cyclic Nucleotide-Gated (HCN) Channels in Epilepsy. Cold Spring Harb Perspect Med 2016; 6:a022384. [PMID: 26931806 DOI: 10.1101/cshperspect.a022384] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Epilepsy is a common brain disorder characterized by the occurrence of spontaneous seizures. These bursts of synchronous firing arise from abnormalities of neuronal networks. Excitability of individual neurons and neuronal networks is largely governed by ion channels and, indeed, abnormalities of a number of ion channels resulting from mutations or aberrant expression and trafficking underlie several types of epilepsy. Here, we focus on the hyperpolarization-activated cyclic nucleotide-gated ion (HCN) channels that conduct Ih current. This conductance plays complex and diverse roles in the regulation of neuronal and network excitability. We describe the normal function of HCN channels and discuss how aberrant expression, assembly, trafficking, and posttranslational modifications contribute to experimental and human epilepsy.
Collapse
Affiliation(s)
- Gary P Brennan
- Department of Pediatrics, University of California-Irvine, Irvine, California 92697-4475
| | - Tallie Z Baram
- Department of Pediatrics, University of California-Irvine, Irvine, California 92697-4475 Departments of Anatomy/Neurobiology and Neurology, University of California-Irvine, Irvine, California 92697-4475
| | - Nicholas P Poolos
- Department of Neurology and Regional Epilepsy Center, University of Washington, Seattle, Washington 98104
| |
Collapse
|
33
|
Liu L, Li CJ, Lu Y, Zong XG, Luo C, Sun J, Guo LJ. Baclofen mediates neuroprotection on hippocampal CA1 pyramidal cells through the regulation of autophagy under chronic cerebral hypoperfusion. Sci Rep 2015; 5:14474. [PMID: 26412641 PMCID: PMC4585985 DOI: 10.1038/srep14474] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2015] [Accepted: 09/01/2015] [Indexed: 12/13/2022] Open
Abstract
GABA receptors play an important role in ischemic brain injury. Studies have indicated that autophagy is closely related to neurodegenerative diseases. However, during chronic cerebral hypoperfusion, the changes of autophagy in the hippocampal CA1 area, the correlation between GABA receptors and autophagy, and their influences on hippocampal neuronal apoptosis have not been well established. Here, we found that chronic cerebral hypoperfusion resulted in rat hippocampal atrophy, neuronal apoptosis, enhancement and redistribution of autophagy, down-regulation of Bcl-2/Bax ratio, elevation of cleaved caspase-3 levels, reduction of surface expression of GABAA receptor α1 subunit and an increase in surface and mitochondrial expression of connexin 43 (CX43) and CX36. Chronic administration of GABAB receptors agonist baclofen significantly alleviated neuronal damage. Meanwhile, baclofen could up-regulate the ratio of Bcl-2/Bax and increase the activation of Akt, GSK-3β and ERK which suppressed cytodestructive autophagy. The study also provided evidence that baclofen could attenuate the decrease in surface expression of GABAA receptor α1 subunit, and down-regulate surface and mitochondrial expression of CX43 and CX36, which might enhance protective autophagy. The current findings suggested that, under chronic cerebral hypoperfusion, the effects of GABAB receptors activation on autophagy regulation could reverse neuronal damage.
Collapse
Affiliation(s)
- Li Liu
- Department of Biochemistry and Molecular Biology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, PR China
| | - Chang-jun Li
- Department of Pharmacology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, PR China
- Neurology Department, Huanggang central hospital, Hubei Province, Huanggang, 438000, PR China
| | - Yun Lu
- Department of Pharmacology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, PR China
| | - Xian-gang Zong
- Center for Integrated Protein Science (CIPSM) and Zentrum für Pharmaforschung, Department Pharmazie, Ludwig-Maximilians-Universität München, 80539 Munich, Germany
| | - Chao Luo
- Department of Biochemistry and Molecular Biology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, PR China
| | - Jun Sun
- Department of Biochemistry and Molecular Biology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, PR China
| | - Lian-jun Guo
- Department of Pharmacology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, PR China
- Key Laboratory of Drug Target Research and Pharmacodynamic Evaluation, Hubei Province, Wuhan 430030, China
| |
Collapse
|
34
|
Read MI, Harrison JC, Kerr DS, Sammut IA. Atenolol offers better protection than clonidine against cardiac injury in kainic acid-induced status epilepticus. Br J Pharmacol 2015; 172:4626-38. [PMID: 25765931 DOI: 10.1111/bph.13132] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2014] [Revised: 02/21/2015] [Accepted: 03/06/2015] [Indexed: 12/31/2022] Open
Abstract
BACKGROUND AND PURPOSE Status epilepticus is increasingly associated with cardiac injury in both clinical and animal studies. The current study examined ECG activity for up to 48 h following kainic acid (KA) seizure induction and compared the potential of atenolol and clonidine to attenuate this cardiac pathology. EXPERIMENTAL APPROACH Sprague-Dawley rats (male, 300-350 g) were implanted with ECG and electrocorticogram electrodes to allow simultaneous telemetric recordings of cardiac and cortical responses during and after KA-induced seizures. Animals were randomized into saline controls, and saline vehicle-, clonidine- or atenolol-pretreated KA groups. KEY RESULTS KA administration in the saline-pretreated group produced an immediate bradycardic response (maximal decrease of 28 ± 6%), coinciding with low-level seizure activity. As high-level seizure behaviours and EEG spiking increased, tachycardia also developed, with a maximum heart rate increase of 38 ± 7% coinciding with QTc prolongation and T wave elevation. Both clonidine and atenolol pretreatment attenuated seizure activity and reduced KA-induced changes in heart rate, QTc interval and T wave amplitude observed during both bradycardic and tachycardic phases in saline-pretreated KA animals. Clonidine, however, failed to reduce the power of EEG frequencies. Atenolol and to a lesser extent clonidine attenuated the cardiac hypercontraction band necrosis, inflammatory infiltration, and oedema at 48 h after KA, relative to the saline-KA group. CONCLUSIONS AND IMPLICATIONS Severe seizure activity in this model was clearly associated with altered ECG activity and cardiac pathology. We suggest that modulation of sympathetic activity by atenolol provides a promising cardioprotective approach in status epilepticus.
Collapse
Affiliation(s)
- M I Read
- Department of Pharmacology, University of Otago School of Medical Sciences, Dunedin, New Zealand
| | - J C Harrison
- Department of Pharmacology, University of Otago School of Medical Sciences, Dunedin, New Zealand
| | - D S Kerr
- Department of Pharmacology, University of Otago School of Medical Sciences, Dunedin, New Zealand
| | - I A Sammut
- Department of Pharmacology, University of Otago School of Medical Sciences, Dunedin, New Zealand
| |
Collapse
|
35
|
Wolfart J, Laker D. Homeostasis or channelopathy? Acquired cell type-specific ion channel changes in temporal lobe epilepsy and their antiepileptic potential. Front Physiol 2015; 6:168. [PMID: 26124723 PMCID: PMC4467176 DOI: 10.3389/fphys.2015.00168] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2015] [Accepted: 05/19/2015] [Indexed: 01/16/2023] Open
Abstract
Neurons continuously adapt the expression and functionality of their ion channels. For example, exposed to chronic excitotoxicity, neurons homeostatically downscale their intrinsic excitability. In contrast, the “acquired channelopathy” hypothesis suggests that proepileptic channel characteristics develop during epilepsy. We review cell type-specific channel alterations under different epileptic conditions and discuss the potential of channels that undergo homeostatic adaptations, as targets for antiepileptic drugs (AEDs). Most of the relevant studies have been performed on temporal lobe epilepsy (TLE), a widespread AED-refractory, focal epilepsy. The TLE patients, who undergo epilepsy surgery, frequently display hippocampal sclerosis (HS), which is associated with degeneration of cornu ammonis subfield 1 pyramidal cells (CA1 PCs). Although the resected human tissue offers insights, controlled data largely stem from animal models simulating different aspects of TLE and other epilepsies. Most of the cell type-specific information is available for CA1 PCs and dentate gyrus granule cells (DG GCs). Between these two cell types, a dichotomy can be observed: while DG GCs acquire properties decreasing the intrinsic excitability (in TLE models and patients with HS), CA1 PCs develop channel characteristics increasing intrinsic excitability (in TLE models without HS only). However, thorough examination of data on these and other cell types reveals the coexistence of protective and permissive intrinsic plasticity within neurons. These mechanisms appear differentially regulated, depending on the cell type and seizure condition. Interestingly, the same channel molecules that are upregulated in DG GCs during HS-related TLE, appear as promising targets for future AEDs and gene therapies. Hence, GCs provide an example of homeostatic ion channel adaptation which can serve as a primer when designing novel anti-epileptic strategies.
Collapse
Affiliation(s)
- Jakob Wolfart
- Oscar Langendorff Institute of Physiology, University of Rostock Rostock, Germany
| | - Debora Laker
- Oscar Langendorff Institute of Physiology, University of Rostock Rostock, Germany
| |
Collapse
|
36
|
Ohno Y, Shimizu S, Tatara A, Imaoku T, Ishii T, Sasa M, Serikawa T, Kuramoto T. Hcn1 is a tremorgenic genetic component in a rat model of essential tremor. PLoS One 2015; 10:e0123529. [PMID: 25970616 PMCID: PMC4430019 DOI: 10.1371/journal.pone.0123529] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2014] [Accepted: 02/18/2015] [Indexed: 01/12/2023] Open
Abstract
Genetic factors are thought to play a major role in the etiology of essential tremor (ET); however, few genetic changes that induce ET have been identified to date. In the present study, to find genes responsible for the development of ET, we employed a rat model system consisting of a tremulous mutant strain, TRM/Kyo (TRM), and its substrain TRMR/Kyo (TRMR). The TRM rat is homozygous for the tremor (tm) mutation and shows spontaneous tremors resembling human ET. The TRMR rat also carries a homozygous tm mutation but shows no tremor, leading us to hypothesize that TRM rats carry one or more genes implicated in the development of ET in addition to the tm mutation. We used a positional cloning approach and found a missense mutation (c. 1061 C>T, p. A354V) in the hyperpolarization-activated cyclic nucleotide-gated 1 channel (Hcn1) gene. The A354V HCN1 failed to conduct hyperpolarization-activated currents in vitro, implicating it as a loss-of-function mutation. Blocking HCN1 channels with ZD7288 in vivo evoked kinetic tremors in nontremulous TRMR rats. We also found neuronal activation of the inferior olive (IO) in both ZD7288-treated TRMR and non-treated TRM rats and a reduced incidence of tremor in the IO-lesioned TRM rats, suggesting a critical role of the IO in tremorgenesis. A rat strain carrying the A354V mutation alone on a genetic background identical to that of the TRM rats showed no tremor. Together, these data indicate that body tremors emerge when the two mutant loci, tm and Hcn1A354V, are combined in a rat model of ET. In this model, HCN1 channels play an important role in the tremorgenesis of ET. We propose that oligogenic, most probably digenic, inheritance is responsible for the genetic heterogeneity of ET.
Collapse
Affiliation(s)
- Yukihiro Ohno
- Laboratory of Pharmacology, Osaka University of Pharmaceutical Sciences, Takatsuki, 569–1094, Japan
| | - Saki Shimizu
- Laboratory of Pharmacology, Osaka University of Pharmaceutical Sciences, Takatsuki, 569–1094, Japan
| | - Ayaka Tatara
- Laboratory of Pharmacology, Osaka University of Pharmaceutical Sciences, Takatsuki, 569–1094, Japan
| | - Takuji Imaoku
- Laboratory of Pharmacology, Osaka University of Pharmaceutical Sciences, Takatsuki, 569–1094, Japan
| | - Takahiro Ishii
- Department of Physiology and Neurobiology, Graduate School of Medicine, Kyoto University, Kyoto, 606–8501, Japan
| | | | - Tadao Serikawa
- Laboratory of Pharmacology, Osaka University of Pharmaceutical Sciences, Takatsuki, 569–1094, Japan
- Institute of Laboratory Animals, Graduate School of Medicine, Kyoto University, Kyoto, 606–8501, Japan
| | - Takashi Kuramoto
- Institute of Laboratory Animals, Graduate School of Medicine, Kyoto University, Kyoto, 606–8501, Japan
| |
Collapse
|
37
|
Moradi Chameh H, Janahmadi M, Semnanian S, Shojaei A, Mirnajafi-Zadeh J. Effect of low frequency repetitive transcranial magnetic stimulation on kindling-induced changes in electrophysiological properties of rat CA1 pyramidal neurons. Brain Res 2015; 1606:34-43. [DOI: 10.1016/j.brainres.2015.02.023] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2014] [Revised: 02/10/2015] [Accepted: 02/13/2015] [Indexed: 12/29/2022]
|
38
|
Williams SB, Hablitz JJ. Differential modulation of repetitive firing and synchronous network activity in neocortical interneurons by inhibition of A-type K(+) channels and Ih. Front Cell Neurosci 2015; 9:89. [PMID: 25852481 PMCID: PMC4364302 DOI: 10.3389/fncel.2015.00089] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2014] [Accepted: 02/26/2015] [Indexed: 12/04/2022] Open
Abstract
GABAergic interneurons provide the main source of inhibition in the neocortex and are important in regulating neocortical network activity. In the presence 4-aminopyridine (4-AP), CNQX, and D-APV, large amplitude GABAA-receptor mediated depolarizing responses were observed in the neocortex. GABAergic networks are comprised of several types of interneurons, each with its own protein expression pattern, firing properties, and inhibitory role in network activity. Voltage-gated ion channels, especially A-type K(+) channels, differentially regulate passive membrane properties, action potential (AP) waveform, and repetitive firing properties in interneurons depending on their composition and localization. HCN channels are known modulators of pyramidal cell intrinsic excitability and excitatory network activity. Little information is available regarding how HCN channels functionally modulate excitability of individual interneurons and inhibitory networks. In this study, we examined the effect of 4-AP on intrinsic excitability of fast-spiking basket cells (FS-BCs) and Martinotti cells (MCs). 4-AP increased the duration of APs in both FS-BCs and MCs. The repetitive firing properties of MCs were differentially affected compared to FS-BCs. We also examined the effect of Ih inhibition on synchronous GABAergic depolarizations and synaptic integration of depolarizing IPSPs. ZD 7288 enhanced the amplitude and area of evoked GABAergic responses in both cell types. Similarly, the frequency and area of spontaneous GABAergic depolarizations in both FS-BCs and MCs were increased in presence of ZD 7288. Synaptic integration of IPSPs in MCs was significantly enhanced, but remained unaltered in FS-BCs. These results indicate that 4-AP differentially alters the firing properties of interneurons, suggesting MCs and FS-BCs may have unique roles in GABAergic network synchronization. Enhancement of GABAergic network synchronization by ZD 7288 suggests that HCN channels attenuate inhibitory network activity.
Collapse
Affiliation(s)
| | - John J. Hablitz
- Department of Neurobiology, Civitan International Research Center and Evelyn F. McKnight Brain Institute, University of Alabama at Birmingham, Birmingham, ALUSA
| |
Collapse
|
39
|
DiFrancesco JC, DiFrancesco D. Dysfunctional HCN ion channels in neurological diseases. Front Cell Neurosci 2015; 6:174. [PMID: 25805968 PMCID: PMC4354400 DOI: 10.3389/fncel.2015.00071] [Citation(s) in RCA: 86] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2014] [Accepted: 02/18/2015] [Indexed: 11/25/2022] Open
Abstract
Hyperpolarization-activated cyclic nucleotide-gated (HCN) channels are expressed as four different isoforms (HCN1-4) in the heart and in the central and peripheral nervous systems. HCN channels are activated by membrane hyperpolarization at voltages close to resting membrane potentials and carry the hyperpolarization-activated current, dubbed If (funny current) in heart and Ih in neurons. HCN channels contribute in several ways to neuronal activity and are responsible for many important cellular functions, including cellular excitability, generation, and modulation of rhythmic activity, dendritic integration, transmission of synaptic potentials, and plasticity phenomena. Because of their role, defective HCN channels are natural candidates in the search for potential causes of neurological disorders in humans. Several data, including growing evidence that some forms of epilepsy are associated with HCN mutations, support the notion of an involvement of dysfunctional HCN channels in different experimental models of the disease. Additionally, some anti-epileptic drugs are known to modify the activity of the Ih current. HCN channels are widely expressed in the peripheral nervous system and recent evidence has highlighted the importance of the HCN2 isoform in the transmission of pain. HCN channels are also present in the midbrain system, where they finely regulate the activity of dopaminergic neurons, and a potential role of these channels in the pathogenesis of Parkinson’s disease has recently emerged. The function of HCN channels is regulated by specific accessory proteins, which control the correct expression and modulation of the neuronal Ih current. Alteration of these proteins can severely interfere with the physiological channel function, potentially predisposing to pathological conditions. In this review we address the present knowledge of the association between HCN dysfunctions and neurological diseases, including clinical, genetic, and physiopathological aspects.
Collapse
Affiliation(s)
- Jacopo C DiFrancesco
- Department of Neurophysiology, Foundation Neurological Institute C. Besta Milano, Italy ; Department of Neurology, San Gerardo Hospital and Laboratory of Neurobiology, Milan Center for Neuroscience, University of Milano-Bicocca Monza, Italy
| | - Dario DiFrancesco
- The PaceLab, Department of Biosciences, University of Milano Milano, Italy
| |
Collapse
|
40
|
Zhou M, Luo P, Lu Y, Li CJ, Wang DS, Lu Q, Xu XL, He Z, Guo LJ. Imbalance of HCN1 and HCN2 expression in hippocampal CA1 area impairs spatial learning and memory in rats with chronic morphine exposure. Prog Neuropsychopharmacol Biol Psychiatry 2015; 56:207-14. [PMID: 25301101 DOI: 10.1016/j.pnpbp.2014.09.010] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/23/2014] [Revised: 09/13/2014] [Accepted: 09/29/2014] [Indexed: 12/12/2022]
Abstract
The hyperpolarization-activated cyclic-nucleotide-gated non-selective cation (HCN) channels play a vital role in the neurological basis underlying nervous system diseases. However, the role of HCN channels in drug addiction is not fully understood. In the present study, we investigated the expression of HCN1 and HCN2 subunits in hippocampal CA1 and the potential molecular mechanisms underlying the modulation of HCN channels in rats with chronic morphine exposure with approaches of electrophysiology, water maze, and Western blotting. We found that chronic morphine exposure (5 mg/kg, sc, for 7 days) caused an inhibition of long-term potentiation (LTP) and impairment of spatial learning and memory, which is associated with a decrease in HCN1, and an increase in HCN2 on cell membrane of hippocampal CA1 area. Additional experiments showed that the imbalance of cell membrane HCN1 and HCN2 expression under chronic morphine exposure was related to an increase in expression of TPR containing Rab8b interacting protein (TRIP8b) (1a-4) and TRIP8b (1b-2), and phosphorylation of protein kinase A (PKA) and adaptor protein 2 μ2 (AP2 μ2). Our results demonstrate the novel information that drug addiction-induced impairment of learning and memory is involved in the imbalance of HCN1 and HCN2 subunits, which is mediated by activation of TRIP8b (1a-4), TRIP8b (1b-2), PKA and AP2 μ2.
Collapse
Affiliation(s)
- Mei Zhou
- Department of Pharmacology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
| | - Pan Luo
- Department of Pharmacology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
| | - Yun Lu
- Department of Pharmacology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
| | - Chang-jun Li
- Department of Pharmacology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
| | - Dian-shi Wang
- Department of Pharmacology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
| | - Qing Lu
- Department of Pharmacology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China; Institute of Brain Research, Huazhong University of Science and Technology, Wuhan 430030, China
| | - Xu-lin Xu
- Department of Pharmacology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China; Institute of Brain Research, Huazhong University of Science and Technology, Wuhan 430030, China
| | - Zhi He
- Department of Neuropsychopharmacology, Medical School of China Three Gorges University, Yichang, 443002, China.
| | - Lian-jun Guo
- Department of Pharmacology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China; Institute of Brain Research, Huazhong University of Science and Technology, Wuhan 430030, China.
| |
Collapse
|
41
|
Kupferman JV, Basu J, Russo MJ, Guevarra J, Cheung SK, Siegelbaum SA. Reelin signaling specifies the molecular identity of the pyramidal neuron distal dendritic compartment. Cell 2014; 158:1335-1347. [PMID: 25201528 DOI: 10.1016/j.cell.2014.07.035] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2014] [Revised: 05/27/2014] [Accepted: 07/17/2014] [Indexed: 12/17/2022]
Abstract
The apical dendrites of many neurons contain proximal and distal compartments that receive synaptic inputs from different brain regions. These compartments also contain distinct complements of ion channels that enable the differential processing of their respective synaptic inputs, making them functionally distinct. At present, the molecular mechanisms that specify dendritic compartments are not well understood. Here, we report that the extracellular matrix protein Reelin, acting through its downstream, intracellular Dab1 and Src family tyrosine kinase signaling cascade, is essential for establishing and maintaining the molecular identity of the distal dendritic compartment of cortical pyramidal neurons. We find that Reelin signaling is required for the striking enrichment of HCN1 and GIRK1 channels in the distal tuft dendrites of both hippocampal CA1 and neocortical layer 5 pyramidal neurons, where the channels actively filter inputs targeted to these dendritic domains.
Collapse
Affiliation(s)
- Justine V Kupferman
- Department of Biology, Kavli Institute, College of Physicians and Surgeons, Columbia University, 1051 Riverside Drive, New York, NY 10032, USA; Department of Neuroscience, Kavli Institute, College of Physicians and Surgeons, Columbia University, 1051 Riverside Drive, New York, NY 10032, USA
| | - Jayeeta Basu
- Department of Neuroscience, Kavli Institute, College of Physicians and Surgeons, Columbia University, 1051 Riverside Drive, New York, NY 10032, USA
| | - Marco J Russo
- Department of Neuroscience, Kavli Institute, College of Physicians and Surgeons, Columbia University, 1051 Riverside Drive, New York, NY 10032, USA
| | - Jenieve Guevarra
- Department of Biology, Kavli Institute, College of Physicians and Surgeons, Columbia University, 1051 Riverside Drive, New York, NY 10032, USA
| | - Stephanie K Cheung
- Department of Neuroscience, Kavli Institute, College of Physicians and Surgeons, Columbia University, 1051 Riverside Drive, New York, NY 10032, USA
| | - Steven A Siegelbaum
- Department of Neuroscience, Kavli Institute, College of Physicians and Surgeons, Columbia University, 1051 Riverside Drive, New York, NY 10032, USA; Department of Pharmacology, Kavli Institute, College of Physicians and Surgeons, Columbia University, 1051 Riverside Drive, New York, NY 10032, USA; Howard Hughes Medical Institute, College of Physicians and Surgeons, Columbia University, 1051 Riverside Drive, New York, NY 10032, USA.
| |
Collapse
|
42
|
Li CJ, Lu Y, Zhou M, Zong XG, Li C, Xu XL, Guo LJ, Lu Q. Activation of GABAB receptors ameliorates cognitive impairment via restoring the balance of HCN1/HCN2 surface expression in the hippocampal CA1 area in rats with chronic cerebral hypoperfusion. Mol Neurobiol 2014; 50:704-20. [PMID: 24838625 DOI: 10.1007/s12035-014-8736-3] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2014] [Accepted: 04/29/2014] [Indexed: 11/30/2022]
Abstract
Hyperpolarization-activated cyclic-nucleotide-gated cation nonselective (HCN) channels are involved in the pathology of nervous system diseases. HCN channels and γ-aminobutyric acid (GABA) receptors can mutually co-regulate the function of neurons in many brain areas. However, little is known about the co-regulation of HCN channels and GABA receptors in the chronic ischemic rats with possible features of vascular dementia. Protein kinase A (PKA) and TPR containing Rab8b interacting protein (TRIP8b) can modulate GABAB receptors cell surface stability and HCN channel trafficking, respectively, and adaptor-associated kinase 1 (AAK1) inhibits the function of the major TRIP8b-interacting protein adaptor protein 2 (AP2) via phosphorylating the AP2 μ2 subunit. Until now, the role of these regulatory factors in chronic cerebral hypoperfusion is unclear. In the present study, we evaluated whether and how HCN channels and GABAB receptors were pathologically altered and investigated neuroprotective effects of GABAB receptors activation and cross-talk networks between GABAB receptors and HCN channels in the hippocampal CA1 area in chronic cerebral hypoperfusion rat model. We found that cerebral hypoperfusion for 5 weeks by permanent occlusion of bilateral common carotid arteries (two-vessel occlusion, 2VO) induced marked spatial and nonspatial learning and memory deficits, significant neuronal loss and decrease in dendritic spine density, impairment of long-term potentiation (LTP) at the Schaffer collateral-CA1 synapses, and reduction of surface expression of GABAB R1, GABAB R2, and HCN1, but increase in HCN2 surface expression. Meanwhile, the protein expression of TRIP8b (1a-4), TRIP8b (1b-2), and AAK1 was significantly decreased. Baclofen, a GABAB receptor agonist, markedly improved the memory impairment and alleviated neuronal damage. Besides, baclofen attenuated the decrease of surface expression of GABAB R1, GABAB R2, and HCN1, but downregulated HCN2 surface expression. Furthermore, baclofen could restore expression of AAK1 protein and significantly increase p-PKA, TRIP8b (1a-4), TRIP8b (1b-2), and p-AP2 μ2 expression. Those findings suggested that, under chronic cerebral hypoperfusion, activation of PKA could attenuate baclofen-induced decrease in surface expression of GABAB R1 and GABAB R2, and activation of GABAB receptors not only increased the expression of TRIP8b (1a-4) and TRIP8b (1b-2) but also regulated the function of TRIP8b via AAK1 and p-AP2 μ2, which restored the balance of HCN1/HCN2 surface expression in rat hippocampal CA1 area, and thus ameliorated cognitive impairment.
Collapse
Affiliation(s)
- Chang-jun Li
- Department of Pharmacology, School of Basic Medical Sciences, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, People's Republic of China
| | | | | | | | | | | | | | | |
Collapse
|
43
|
De novo mutations in HCN1 cause early infantile epileptic encephalopathy. Nat Genet 2014; 46:640-5. [PMID: 24747641 DOI: 10.1038/ng.2952] [Citation(s) in RCA: 150] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2013] [Accepted: 03/17/2014] [Indexed: 12/13/2022]
Abstract
Hyperpolarization-activated, cyclic nucleotide-gated (HCN) channels contribute to cationic Ih current in neurons and regulate the excitability of neuronal networks. Studies in rat models have shown that the Hcn1 gene has a key role in epilepsy, but clinical evidence implicating HCN1 mutations in human epilepsy is lacking. We carried out exome sequencing for parent-offspring trios with fever-sensitive, intractable epileptic encephalopathy, leading to the discovery of two de novo missense HCN1 mutations. Screening of follow-up cohorts comprising 157 cases in total identified 4 additional amino acid substitutions. Patch-clamp recordings of Ih currents in cells expressing wild-type or mutant human HCN1 channels showed that the mutations had striking but divergent effects on homomeric channels. Individuals with mutations had clinical features resembling those of Dravet syndrome with progression toward atypical absences, intellectual disability and autistic traits. These findings provide clear evidence that de novo HCN1 point mutations cause a recognizable early-onset epileptic encephalopathy in humans.
Collapse
|
44
|
Powell KL, Jones NC, Kennard JT, Ng C, Urmaliya V, Lau S, Tran A, Zheng T, Ozturk E, Dezsi G, Megatia I, Delbridge LM, Pinault D, Reid CA, White PJ, O'Brien TJ. HCN channelopathy and cardiac electrophysiologic dysfunction in genetic and acquired rat epilepsy models. Epilepsia 2014; 55:609-20. [PMID: 24592881 DOI: 10.1111/epi.12563] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/13/2014] [Indexed: 01/20/2023]
Abstract
OBJECTIVE Evidence from animal and human studies indicates that epilepsy can affect cardiac function, although the molecular basis of this remains poorly understood. Hyperpolarization-activated cyclic nucleotide-gated (HCN) channels generate pacemaker activity and modulate cellular excitability in the brain and heart, with altered expression and function associated with epilepsy and cardiomyopathies. Whether HCN expression is altered in the heart in association with epilepsy has not been investigated previously. We studied cardiac electrophysiologic properties and HCN channel subunit expression in rat models of genetic generalized epilepsy (Genetic Absence Epilepsy Rats from Strasbourg, GAERS) and acquired temporal lobe epilepsy (post-status epilepticus SE). We hypothesized that the development of epilepsy is associated with altered cardiac electrophysiologic function and altered cardiac HCN channel expression. METHODS Electrocardiography studies were recorded in vivo in rats and in vitro in isolated hearts. Cardiac HCN channel messenger RNA (mRNA) and protein expression were measured using quantitative PCR and Western blotting respectively. RESULTS Cardiac electrophysiology was significantly altered in adult GAERS, with slower heart rate, shorter QRS duration, longer QTc interval, and greater standard deviation of RR intervals compared to control rats. In the post-SE model, we observed similar interictal changes in several of these parameters, and we also observed consistent and striking bradycardia associated with the onset of ictal activity. Molecular analysis demonstrated significant reductions in cardiac HCN2 mRNA and protein expression in both models, providing a molecular correlate of these electrophysiologic abnormalities. SIGNIFICANCE These results demonstrate that ion channelopathies and cardiac dysfunction can develop as a secondary consequence of chronic epilepsy, which may have relevance for the pathophysiology of cardiac dysfunction in patients with epilepsy.
Collapse
Affiliation(s)
- Kim L Powell
- Department of Medicine, The Royal Melbourne Hospital, The University of Melbourne, Parkville, Victoria, Australia
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
45
|
Vivash L, Gregoire MC, Bouilleret V, Berard A, Wimberley C, Binns D, Roselt P, Katsifis A, Myers DE, Hicks RJ, O'Brien TJ, Dedeurwaerdere S. In vivo measurement of hippocampal GABAA/cBZR density with [18F]-flumazenil PET for the study of disease progression in an animal model of temporal lobe epilepsy. PLoS One 2014; 9:e86722. [PMID: 24466212 PMCID: PMC3897736 DOI: 10.1371/journal.pone.0086722] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2013] [Accepted: 12/15/2013] [Indexed: 11/18/2022] Open
Abstract
Purpose Imbalance of inhibitory GABAergic neurotransmission has been proposed to play a role in the pathogenesis of temporal lobe epilepsy (TLE). This study aimed to investigate whether [18F]-flumazenil ([18F]-FMZ) PET could be used to non-invasively characterise GABAA/central benzodiazepine receptor (GABAA/cBZR) density and affinity in vivo in the post-kainic acid status epilepticus (SE) model of TLE. Methods Dynamic [18F]-FMZ -PET scans using a multi-injection protocol were acquired in four male wistar rats for validation of the partial saturation model (PSM). SE was induced in eight male Wistar rats (10 weeks of age) by i.p. injection of kainic acid (7.5–25 mg/kg), while control rats (n = 7) received saline injections. Five weeks post-SE, an anatomic MRI scan was acquired and the following week an [18F]-FMZ PET scan (3.6–4.6 nmol). The PET data was co-registered to the MRI and regions of interest drawn on the MRI for selected structures. A PSM was used to derive receptor density and apparent affinity from the [18F]-FMZ PET data. Key Findings The PSM was found to adequately model [18F]-FMZ binding in vivo. There was a significant decrease in hippocampal receptor density in the SE group (p<0.01), accompanied by an increase in apparent affinity (p<0.05) compared to controls. No change in cortical receptor binding was observed. Hippocampal volume reduction and cell loss was only seen in a subset of animals. Histological assessment of hippocampal cell loss was significantly correlated with hippocampal volume measured by MRI (p<0.05), but did not correlate with [18F]-FMZ binding. Significance Alterations to hippocampal GABAA/cBZR density and affinity in the post-kainic acid SE model of TLE are detectable in vivo with [18F]-FMZ PET and a PSM. These changes are independent from hippocampal cell and volume loss. [18F]-FMZ PET is useful for investigating the role that changes GABAA/cBZR density and binding affinity play in the pathogenesis of TLE.
Collapse
Affiliation(s)
- Lucy Vivash
- Department of Medicine, Royal Melbourne Hospital, University of Melbourne, Melbourne, Victoria, Australia
| | - Marie-Claude Gregoire
- Department of LifeSciences, Australian Nuclear Science and Technology Organisation, Sydney, New South Wales, Australia
| | - Viviane Bouilleret
- Department of Medicine, Royal Melbourne Hospital, University of Melbourne, Melbourne, Victoria, Australia
| | - Alexis Berard
- Department of LifeSciences, Australian Nuclear Science and Technology Organisation, Sydney, New South Wales, Australia
| | - Catriona Wimberley
- Department of LifeSciences, Australian Nuclear Science and Technology Organisation, Sydney, New South Wales, Australia
| | - David Binns
- The Centre for Molecular Imaging, Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia
| | - Peter Roselt
- The Centre for Molecular Imaging, Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia
| | - Andrew Katsifis
- Department of LifeSciences, Australian Nuclear Science and Technology Organisation, Sydney, New South Wales, Australia
| | - Damian E. Myers
- Department of Medicine, Royal Melbourne Hospital, University of Melbourne, Melbourne, Victoria, Australia
| | - Rodney J. Hicks
- The Centre for Molecular Imaging, Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia
| | - Terence J. O'Brien
- Department of Medicine, Royal Melbourne Hospital, University of Melbourne, Melbourne, Victoria, Australia
- * E-mail:
| | - Stefanie Dedeurwaerdere
- Department of Medicine, Royal Melbourne Hospital, University of Melbourne, Melbourne, Victoria, Australia
- Department of Translational Neurosciences, University of Antwerp, Wilrijk, Belgium
| |
Collapse
|
46
|
He C, Chen F, Li B, Hu Z. Neurophysiology of HCN channels: From cellular functions to multiple regulations. Prog Neurobiol 2014; 112:1-23. [DOI: 10.1016/j.pneurobio.2013.10.001] [Citation(s) in RCA: 230] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2012] [Revised: 10/01/2013] [Accepted: 10/07/2013] [Indexed: 12/18/2022]
|
47
|
Phillips AM, Kim T, Vargas E, Petrou S, Reid CA. Spike-and-wave discharge mediated reduction in hippocampal HCN1 channel function associates with learning deficits in a genetic mouse model of epilepsy. Neurobiol Dis 2013; 64:30-5. [PMID: 24368169 DOI: 10.1016/j.nbd.2013.12.007] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2013] [Revised: 11/22/2013] [Accepted: 12/13/2013] [Indexed: 01/18/2023] Open
Abstract
The GABAAγ2(R43Q) mouse is an established model of absence epilepsy displaying spontaneous spike-and-wave discharges (SWD) and associated behavioral arrest. Absence epilepsy typically results from cortico-thalamic networks. Nevertheless, there is increasing evidence for changes in hippocampal metabolism and electrical behavior, consistent with a link between absence seizures and hippocampus-related co-morbidities. Hyperpolarization-activated-cyclic-nucleotide-gated (HCN) channels are known to be transcriptionally regulated in a number of seizure models. Here we investigate the expression and function of these channels in the hippocampus of the genetic epilepsy model. A reduction in HCN1, but not HCN2 transcript, was observed in GABAAγ2(R43Q) mice relative to their littermate controls. In contrast, no change in HCN1 transcript was noted at an age prior to seizure expression or in a SWD-free model in which the R43Q mutation has been crossed into a seizure-resistant genetic background. Whole-cell recordings from CA1 pyramidal neurons confirm a reduction in Ih in the GABAAγ2(R43Q) mouse. Further, a left-shift in half-activation of the Ih conductance-voltage relationship is consistent with a reduction in HCN1 with no change in HCN2 channel expression. Behavioral analysis using the Morris water maze indicates that GABAAγ2(R43Q) mice are unable to learn as effectively as their wildtype littermates suggesting a deficit in hippocampal-based learning. SWD-free mice harboring the R43Q mutation had no learning deficit. We conclude that SWDs reduce hippocampal HCN1 expression and function, and that the reduction associates with a spatial learning deficit.
Collapse
Affiliation(s)
- A Marie Phillips
- Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Parkville 3010, Australia; Department of Genetics, University of Melbourne, Parkville 3010, Australia.
| | - Taehwan Kim
- Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Parkville 3010, Australia; Centre for Neural Engineering, The University of Melbourne, Parkville 3010, Melbourne, Australia.
| | - Ernesto Vargas
- Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Parkville 3010, Australia.
| | - Steven Petrou
- Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Parkville 3010, Australia; Centre for Neural Engineering, The University of Melbourne, Parkville 3010, Melbourne, Australia; Department of Anatomy and Neuroscience, The University of Melbourne, Parkville 3010, Melbourne, Australia.
| | - Christopher A Reid
- Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Parkville 3010, Australia.
| |
Collapse
|
48
|
Albertson AJ, Williams SB, Hablitz JJ. Regulation of epileptiform discharges in rat neocortex by HCN channels. J Neurophysiol 2013; 110:1733-43. [PMID: 23864381 PMCID: PMC3798942 DOI: 10.1152/jn.00955.2012] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2012] [Accepted: 07/17/2013] [Indexed: 11/22/2022] Open
Abstract
Hyperpolarization-activated, cyclic nucleotide-gated, nonspecific cation (HCN) channels have a well-characterized role in regulation of cellular excitability and network activity. The role of these channels in control of epileptiform discharges is less thoroughly understood. This is especially pertinent given the altered HCN channel expression in epilepsy. We hypothesized that inhibition of HCN channels would enhance bicuculline-induced epileptiform discharges. Whole cell recordings were obtained from layer (L)2/3 and L5 pyramidal neurons and L1 and L5 GABAergic interneurons. In the presence of bicuculline (10 μM), HCN channel inhibition with ZD 7288 (20 μM) significantly increased the magnitude (defined as area) of evoked epileptiform events in both L2/3 and L5 neurons. We recorded activity associated with epileptiform discharges in L1 and L5 interneurons to test the hypothesis that HCN channels regulate excitatory synaptic inputs differently in interneurons versus pyramidal neurons. HCN channel inhibition increased the magnitude of epileptiform events in both L1 and L5 interneurons. The increased magnitude of epileptiform events in both pyramidal cells and interneurons was due to an increase in network activity, since holding cells at depolarized potentials under voltage-clamp conditions to minimize HCN channel opening did not prevent enhancement in the presence of ZD 7288. In neurons recorded with ZD 7288-containing pipettes, bath application of the noninactivating inward cationic current (Ih) antagonist still produced increases in epileptiform responses. These results show that epileptiform discharges in disinhibited rat neocortex are modulated by HCN channels.
Collapse
Affiliation(s)
- Asher J Albertson
- Department of Neurobiology, Civitan International Research Center, and Evelyn F. McKnight Brain Institute, University of Alabama at Birmingham, Birmingham, Alabama
| | | | | |
Collapse
|
49
|
Shah MM, Huang Z, Martinello K. HCN and KV7 (M-) channels as targets for epilepsy treatment. Neuropharmacology 2013; 69:75-81. [PMID: 22446478 PMCID: PMC4104618 DOI: 10.1016/j.neuropharm.2012.03.005] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2011] [Revised: 02/26/2012] [Accepted: 03/09/2012] [Indexed: 12/11/2022]
Abstract
Voltage-gated ion channels are important determinants of cellular excitability. The Hyperpolarization-activated Cyclic Nucleotide-gated (HCN) and KV7 (M-) channels are voltage-gated ion channels. Both channels are activated at sub-threshold potentials and have biophysical properties that mirror each other. KV7 channels inhibit neuronal excitability. Thus, mutations in KV7 channels that are associated with Benign Familial Neonatal Convulsions (BFNC) are likely to be epileptogenic. Mutations in HCN channels have also been associated with idiopathic epilepsies such as GEFS+. In addition, HCN channel expression and function are modulated during symptomatic epilepsies such as temporal lobe epilepsy. It is, though, unclear as to whether the changes in HCN channel expression and function associated with the various forms of epilepsy promote epileptogenesis or are adaptive. In this review, we discuss this as well as the potential for KV7 and HCN channels as drug targets for the treatment of epilepsy. This article is part of the Special Issue entitled 'New Targets and Approaches to the Treatment of Epilepsy'.
Collapse
Affiliation(s)
- Mala M Shah
- Department of Pharmacology, The School of Pharmacy, University of London, 29-39 Brunswick Square, London WC1N 1AX, United Kingdom.
| | | | | |
Collapse
|
50
|
Noam Y, Raol YH, Holmes GL. Searching for new targets for treatment of pediatric epilepsy. Epilepsy Behav 2013; 26:253-60. [PMID: 23219411 PMCID: PMC3595393 DOI: 10.1016/j.yebeh.2012.09.022] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/01/2012] [Accepted: 09/06/2012] [Indexed: 12/13/2022]
Abstract
The highest incidence of seizures in humans occurs during the first year of life. The high susceptibility to seizures in neonates and infants is paralleled by animal studies showing a high propensity to seizures during early life. The immature brain is highly susceptible to seizures because of an imbalance of excitation and inhibition. While the primary outcome determinant of early-life seizures is etiology, there is evidence that seizures which are frequent or prolonged can result in long-term adverse consequences, and there is a consensus that recurrent early-life seizures should be treated. Unfortunately, seizures in many neonates and children remain refractory to therapy. There is therefore a pressing need for new seizure drugs as well as antiepileptic targets in children. In this review, we focus on mechanisms of early-life seizures, such as hypoxia-ischemia, and novel molecular targets, including the hyperpolarization-activated cyclic nucleotide-gated channels.
Collapse
Affiliation(s)
- Yoav Noam
- Department of Anatomy & Neurobiology, University of California-Irvine, Irvine, California
| | - Yogendra H. Raol
- Division of Neurology, Department of Pediatrics, School of Medicine, University of Colorado Denver, Aurora, Colorado
| | - Gregory L. Holmes
- Department of Neurology Geisel School of Medicine at Dartmouth, Hanover, New Hampshire
| |
Collapse
|