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Popova EY, Kawasawa YI, Leung M, Barnstable CJ. Temporal changes in mouse hippocampus transcriptome after pilocarpine-induced seizures. Front Neurosci 2024; 18:1384805. [PMID: 39040630 PMCID: PMC11260795 DOI: 10.3389/fnins.2024.1384805] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2024] [Accepted: 06/07/2024] [Indexed: 07/24/2024] Open
Abstract
Introduction Status epilepticus (SE) is a seizure lasting more than 5 min that can have lethal consequences or lead to various neurological disorders, including epilepsy. Using a pilocarpine-induced SE model in mice we investigated temporal changes in the hippocampal transcriptome. Methods We performed mRNA-seq and microRNA-seq analyses at various times after drug treatment. Results At 1 h after the start of seizures, hippocampal cells upregulated transcription of immediate early genes and genes involved in the IGF-1, ERK/MAPK and RNA-PolII/transcription pathways. At 8 h, we observed changes in the expression of genes associated with oxidative stress, overall transcription downregulation, particularly for genes related to mitochondrial structure and function, initiation of a stress response through regulation of ribosome and translation/EIF2 signaling, and upregulation of an inflammatory response. During the middle of the latent period, 36 h, we identified upregulation of membrane components, cholesterol synthesis enzymes, channels, and extracellular matrix (ECM), as well as an increased inflammatory response. At the end of the latent period, 120 h, most changes in expression were in genes involved in ion transport, membrane channels, and synapses. Notably, we also elucidated the involvement of novel pathways, such as cholesterol biosynthesis pathways, iron/BMP/ferroptosis pathways, and circadian rhythms signaling in SE and epileptogenesis. Discussion These temporal changes in metabolic reactions indicate an immediate response to injury followed by recovery and regeneration. CREB was identified as the main upstream regulator. Overall, our data provide new insights into molecular functions and cellular processes involved at different stages of seizures and offer potential avenues for effective therapeutic strategies.
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Affiliation(s)
- Evgenya Y. Popova
- Department of Neural and Behavioral Sciences, Penn State University College of Medicine, Hershey, PA, United States
- Penn State Hershey Eye Center, Hershey, PA, United States
| | - Yuka Imamura Kawasawa
- Department of Pharmacology, Penn State University College of Medicine, Hershey, PA, United States
- Center for Cancer Genomics and Precision Oncology, Wake Forest Baptist Comprehensive Cancer Center, Winston Salem, NC, United States
| | - Ming Leung
- Center for Cancer Genomics and Precision Oncology, Wake Forest Baptist Comprehensive Cancer Center, Winston Salem, NC, United States
| | - Colin J. Barnstable
- Department of Neural and Behavioral Sciences, Penn State University College of Medicine, Hershey, PA, United States
- Penn State Hershey Eye Center, Hershey, PA, United States
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2
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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.
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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.
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3
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Alahmadi AA, Alotaibi NO, Hakami NY, Almutairi RS, Darwesh AM, Abdeen R, Alghamdi J, Abdulaal OM, Alsharif W, Sultan SR, Kanbayti IH. Gender and cytoarchitecture differences: Functional connectivity of the hippocampal sub-regions. Heliyon 2023; 9:e20389. [PMID: 37780771 PMCID: PMC10539667 DOI: 10.1016/j.heliyon.2023.e20389] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2022] [Revised: 07/27/2023] [Accepted: 09/20/2023] [Indexed: 10/03/2023] Open
Abstract
Introduction The hippocampus plays a significant role in learning, memory encoding, and spatial navigation. Typically, the hippocampus is investigated as a whole region of interest. However, recent work has developed fully detailed atlases based on cytoarchitecture properties of brain regions, and the hippocampus has been sub-divided into seven sub-areas that have structural differences in terms of distinct numbers of cells, neurons, and other structural and chemical properties. Moreover, gender differences are of increasing concern in neuroscience research. Several neuroscience studies have found structural and functional variations between the brain regions of females and males, and the hippocampus is one of these regions. Aim The aim of this study to explore whether the cytoarchitecturally distinct sub-regions of the hippocampus have varying patterns of functional connectivity with different networks of the brain and how these functional connections differ in terms of gender differences. Method This study investigated 200 healthy participants using seed-based resting-state functional magnetic resonance imaging (rsfMRI). The primary aim of this study was to explore the resting connectivity and gender distinctions associated with specific sub-regions of the hippocampus and their relationship with major functional brain networks. Results The findings revealed that the majority of the seven hippocampal sub-regions displayed functional connections with key brain networks, and distinct patterns of functional connectivity were observed between the hippocampal sub-regions and various functional networks within the brain. Notably, the default and visual networks exhibited the most consistent functional connections. Additionally, gender-based analysis highlighted evident functional resemblances and disparities, particularly concerning the anterior section of the hippocampus. Conclusion This study highlighted the functional connectivity patterns and involvement of the hippocampal sub-regions in major brain functional networks, indicating that the hippocampus should be investigated as a region of multiple distinct functions and should always be examined as sub-regions of interest. The results also revealed clear gender differences in functional connectivity.
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Affiliation(s)
- Adnan A.S. Alahmadi
- Radiologic Sciences, Faculty of Applied Medical Sciences, King Abdulaziz University, Jeddah, Saudi Arabia
- NMR Research Unit, Department of Neuroinflammation, Queen Square MS Centre, UCL Queen Square Institute of Neurology, London, United Kingdom
| | - Nada O. Alotaibi
- Radiologic Sciences, Faculty of Applied Medical Sciences, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Norah Y. Hakami
- Radiologic Sciences, Faculty of Applied Medical Sciences, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Raghad S. Almutairi
- Radiologic Sciences, Faculty of Applied Medical Sciences, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Afnan M.F. Darwesh
- Radiologic Sciences, Faculty of Applied Medical Sciences, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Rawan Abdeen
- Radiologic Sciences, Faculty of Applied Medical Sciences, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Jamaan Alghamdi
- Radiologic Sciences, Faculty of Applied Medical Sciences, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Osamah M. Abdulaal
- Diagnostic Radiology Technology, College of Applied Medical Sciences, Taibah University, Madina, Saudi Arabia
| | - Walaa Alsharif
- Diagnostic Radiology Technology, College of Applied Medical Sciences, Taibah University, Madina, Saudi Arabia
| | - Salahaden R. Sultan
- Radiologic Sciences, Faculty of Applied Medical Sciences, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Ibrahem H. Kanbayti
- Radiologic Sciences, Faculty of Applied Medical Sciences, King Abdulaziz University, Jeddah, Saudi Arabia
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Utsumi Y, Taketoshi M, Miwa M, Tominaga Y, Tominaga T. Assessing seizure liability in vitro with voltage-sensitive dye imaging in mouse hippocampal slices. Front Cell Neurosci 2023; 17:1217368. [PMID: 37680865 PMCID: PMC10481167 DOI: 10.3389/fncel.2023.1217368] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2023] [Accepted: 08/09/2023] [Indexed: 09/09/2023] Open
Abstract
Non-clinical toxicology is a major cause of drug candidate attrition during development. In particular, drug-induced seizures are the most common finding in central nervous system (CNS) toxicity. Current safety pharmacology tests for assessing CNS functions are often inadequate in detecting seizure-inducing compounds early in drug development, leading to significant delays. This paper presents an in vitro seizure liability assay using voltage-sensitive dye (VSD) imaging techniques in hippocampal brain slices, offering a powerful alternative to traditional electrophysiological methods. Hippocampal slices were isolated from mice, and VSD optical responses evoked by stimulating the Schaffer collateral pathway were recorded and analyzed in the stratum radiatum (SR) and stratum pyramidale (SP). VSDs allow for the comprehensive visualization of neuronal action potentials and postsynaptic potentials on a millisecond timescale. By employing this approach, we investigated the in vitro drug-induced seizure liability of representative pro-convulsant compounds. Picrotoxin (PiTX; 1-100 μM), gabazine (GZ; 0.1-10 μM), and 4-aminopyridine (4AP; 10-100 μM) exhibited seizure-like responses in the hippocampus, but pilocarpine hydrochloride (Pilo; 10-100 μM) did not. Our findings demonstrate the potential of VSD-based assays in identifying seizurogenic compounds during early drug discovery, thereby reducing delays in drug development and providing insights into the mechanisms underlying seizure induction and the associated risks of pro-convulsant compounds.
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Affiliation(s)
- Yuichi Utsumi
- Graduate School of Pharmaceutical Sciences, Tokushima Bunri University, Sanuki, Japan
- Institute of Neuroscience, Tokushima Bunri University, Sanuki, Japan
| | - Makiko Taketoshi
- Institute of Neuroscience, Tokushima Bunri University, Sanuki, Japan
| | - Michiko Miwa
- Kagawa School of Pharmaceutical Sciences, Tokushima Bunri University, Sanuki, Japan
| | - Yoko Tominaga
- Institute of Neuroscience, Tokushima Bunri University, Sanuki, Japan
| | - Takashi Tominaga
- Graduate School of Pharmaceutical Sciences, Tokushima Bunri University, Sanuki, Japan
- Institute of Neuroscience, Tokushima Bunri University, Sanuki, Japan
- Kagawa School of Pharmaceutical Sciences, Tokushima Bunri University, Sanuki, Japan
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Oliva A, Fernandez-Ruiz A, Karaba LA. CA2 orchestrates hippocampal network dynamics. Hippocampus 2023; 33:241-251. [PMID: 36575880 PMCID: PMC9974898 DOI: 10.1002/hipo.23495] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2022] [Revised: 11/25/2022] [Accepted: 12/11/2022] [Indexed: 12/29/2022]
Abstract
The hippocampus is composed of various subregions: CA1, CA2, CA3, and the dentate gyrus (DG). Despite the abundant hippocampal research literature, until recently, CA2 received little attention. The development of new genetic and physiological tools allowed recent studies characterizing the unique properties and functional roles of this hippocampal subregion. Despite its small size, the cellular content of CA2 is heterogeneous at the molecular and physiological levels. CA2 has been heavily implicated in social behaviors, including social memory. More generally, the mechanisms by which the hippocampus is involved in memory include the reactivation of neuronal ensembles following experience. This process is coordinated by synchronous network events known as sharp-wave ripples (SWRs). Recent evidence suggests that CA2 plays an important role in the generation of SWRs. The unique connectivity and physiological properties of CA2 pyramidal cells make this region a computational hub at the core of hippocampal information processing. Here, we review recent findings that support the role of CA2 in coordinating hippocampal network dynamics from a systems neuroscience perspective.
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Affiliation(s)
- Azahara Oliva
- Department of Neurobiology and Behavior, Cornell University, Ithaca, New York, USA
| | | | - Lindsay A Karaba
- Department of Neurobiology and Behavior, Cornell University, Ithaca, New York, USA
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6
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Zhao K, Li Y, Yang X, Zhou L. The Impact of Altered HCN1 Expression on Brain Function and Its Relationship with Epileptogenesis. Curr Neuropharmacol 2023; 21:2070-2078. [PMID: 37366350 PMCID: PMC10556362 DOI: 10.2174/1570159x21666230214110333] [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: 09/30/2022] [Revised: 11/13/2022] [Accepted: 12/06/2022] [Indexed: 03/08/2023] Open
Abstract
Hyperpolarization-activated cyclic nucleotide-gated cation channel 1 (HCN1) is predominantly expressed in neurons from the neocortex and hippocampus, two important regions related to epilepsy. Both animal models for epilepsy and epileptic patients show decreased HCN1 expression and HCN1-mediated Ih current. It has been shown in neuroelectrophysiological experiments that a decreased Ih current can increase neuronal excitability. However, some studies have shown that blocking the Ih current in vivo can exert antiepileptic effects. This paradox raises an important question regarding the causal relationship between HCN1 alteration and epileptogenesis, which to date has not been elucidated. In this review, we summarize the literature related to HCN1 and epilepsy, aiming to find a possible explanation for this paradox, and explore the correlation between HCN1 and the mechanism of epileptogenesis. We analyze the alterations in the expression and distribution of HCN1 and the corresponding impact on brain function in epilepsy. In addition, we also discuss the effect of blocking Ih on epilepsy symptoms. Addressing these issues will help to inspire new strategies to explore the relationship between HCN1 and epileptogenesis, and ultimately promote the development of new targets for epilepsy therapy.
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Affiliation(s)
- Ke Zhao
- Department of Neurology, The Seventh Affliated Hospital of Sun Yet-sen University, No. 628, Zhenyuan Road, Xinhu Street, Guangming District, Shenzhen, China
| | - Yinchao Li
- Department of Neurology, The Seventh Affliated Hospital of Sun Yet-sen University, No. 628, Zhenyuan Road, Xinhu Street, Guangming District, Shenzhen, China
| | - Xiaofeng Yang
- Guangzhou Laboratory, Guangzhou, No. 9 XingDaoHuanBei Road, Guangzhou International Bio Island, Guangzhou 510005, Guangdong Province, China
| | - Liemin Zhou
- Department of Neurology, The Seventh Affliated Hospital of Sun Yet-sen University, No. 628, Zhenyuan Road, Xinhu Street, Guangming District, Shenzhen, China
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7
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Sahin H, Yucel O, Emik S, Senturk GE. Protective Effects of Intranasally Administrated Oxytocin-Loaded Nanoparticles on Pentylenetetrazole-Kindling Epilepsy in Terms of Seizure Severity, Memory, Neurogenesis, and Neuronal Damage. ACS Chem Neurosci 2022; 13:1923-1937. [PMID: 35713692 PMCID: PMC9264347 DOI: 10.1021/acschemneuro.2c00124] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
Abstract
![]()
Pentylenetetrazole
(PTZ)-induced kindling is an animal model for
studying human temporal lobe epilepsy (TLE), which is characterized
by alterations of hippocampal neurons and memory. Although the intranasal
(IN) administration of oxytocin (OT) has limited efficiency, nanoparticles
(NPs) are a promising candidate to deliver OT to the brain. However,
there are very limited data on epilepsy research about oxytocin-loaded
nanoparticles (NP-OTs). The aim of this study is to investigate the
effects of IN administration of chronic NP-OTs on the hippocampus
of PTZ-induced male epileptic rats in terms of seizure severity, memory,
neurogenesis, and neuronal damage. Saline/OT/NP-OTs were administrated
to both control (Ctrl) and PTZ groups intranasally. Consequently,
saline and PTZ were injected, respectively, 25 times every 48 h. Then,
seizure severity (score and latency) was calculated for the PTZ groups.
A spatial working memory evaluation test (SWMET) was performed after
the last injection. Hippocampus histopathology, neurogenesis, and
apoptosis were demonstrated. Serum total antioxidant status (TAS)
and total oxidant status (TOS) levels and the oxidative stress index
(OSI) were measured. We showed that OTs and NP-OTs prevented the kindling
development and had positive effects on seizure severity. SWMET-related
behaviors were also recovered in the PTZ + NP-OT group. A significant
increase of neurogenesis and decrease of apoptosis in the hippocampus
of the PTZ + NP-OT group were observed, while OTs and NP-OTs had protective
effects against PTZ-induced damage to hippocampal neurons. Our results
indicate that the chronic administration of NP-OTs may have positive
effects on hippocampal damage via increasing neurogenesis and decreasing
apoptosis and seizure severity.
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Affiliation(s)
- Hakan Sahin
- Department of Histology and Embryology, Cerrahpasa Faculty of Medicine, Istanbul University─Cerrahpasa, Istanbul 34098, Turkey
| | - Oguz Yucel
- Department of Chemical Engineering, Faculty of Engineering, Istanbul University─Cerrahpasa, Istanbul 34320, Turkey
| | - Serkan Emik
- Department of Chemical Engineering, Faculty of Engineering, Istanbul University─Cerrahpasa, Istanbul 34320, Turkey
| | - Gozde Erkanli Senturk
- Department of Histology and Embryology, Cerrahpasa Faculty of Medicine, Istanbul University─Cerrahpasa, Istanbul 34098, Turkey
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8
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Sadeh S, Clopath C. Inhibitory stabilization and cortical computation. Nat Rev Neurosci 2020; 22:21-37. [PMID: 33177630 DOI: 10.1038/s41583-020-00390-z] [Citation(s) in RCA: 54] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/22/2020] [Indexed: 12/22/2022]
Abstract
Neuronal networks with strong recurrent connectivity provide the brain with a powerful means to perform complex computational tasks. However, high-gain excitatory networks are susceptible to instability, which can lead to runaway activity, as manifested in pathological regimes such as epilepsy. Inhibitory stabilization offers a dynamic, fast and flexible compensatory mechanism to balance otherwise unstable networks, thus enabling the brain to operate in its most efficient regimes. Here we review recent experimental evidence for the presence of such inhibition-stabilized dynamics in the brain and discuss their consequences for cortical computation. We show how the study of inhibition-stabilized networks in the brain has been facilitated by recent advances in the technological toolbox and perturbative techniques, as well as a concomitant development of biologically realistic computational models. By outlining future avenues, we suggest that inhibitory stabilization can offer an exemplary case of how experimental neuroscience can progress in tandem with technology and theory to advance our understanding of the brain.
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Affiliation(s)
- Sadra Sadeh
- Bioengineering Department, Imperial College London, London, UK
| | - Claudia Clopath
- Bioengineering Department, Imperial College London, London, UK.
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Kaczmarska A, José-López R, Czopowicz M, Lazzerini K, Leblond G, Stalin C, Gutierrez-Quintana R. Postencephalitic epilepsy in dogs with meningoencephalitis of unknown origin: Clinical features, risk factors, and long-term outcome. J Vet Intern Med 2020; 34:808-820. [PMID: 31990104 PMCID: PMC7096646 DOI: 10.1111/jvim.15687] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2019] [Accepted: 12/10/2019] [Indexed: 12/27/2022] Open
Abstract
Background Although the presence of seizures in dogs with meningoencephalitis of unknown origin (MUO) has been associated with shorter survival times, data regarding the prevalence and risk factors for postencephalitic epilepsy (PEE) is lacking. Objectives To describe the clinical features, prevalence, risk factors, and long‐term outcome of PEE in dogs with MUO. Animals Sixty‐one dogs with presumptive diagnosis of MUO based on the clinicopathological and diagnostic imaging findings. Methods Retrospective study. Cases were identified by search of hospital medical records for dogs with suspected or confirmed MUO. Medical records of dogs meeting inclusion criteria were reviewed. Signalment, seizure history, clinicopathologic, and magnetic resonance imaging (MRI) findings were recorded. Results Among 61 dogs at risk of PEE, 14 (23%) dogs developed PEE. Three of 14 dogs with PEE (21%) developed drug‐resistant epilepsy. Dogs with PEE were younger (P = .03; ORadjusted = 0.75; 95% confidence interval [CI], 0.58‐0.98) and had significantly shorter survival times (log‐rank test P = .04) when compared to dogs that did not develop epilepsy. The risk factors associated with the development of PEE were the presence of acute symptomatic seizures (ASS; P = .04; ORadjusted = 4.76; 95% CI, 1.11‐20.4) and MRI lesions in the hippocampus (P = .04; ORadjusted = 4.75; 95% CI, 1.07‐21.0). Conclusions and Clinical Importance Dogs with MUO and seizures at the early stage of the disease (ASS) seem to be at a higher risk of developing PEE.
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Affiliation(s)
- Adriana Kaczmarska
- Small Animal Hospital, School of Veterinary Medicine, University of Glasgow, Glasgow, United Kingdom
| | - Roberto José-López
- Small Animal Hospital, School of Veterinary Medicine, University of Glasgow, Glasgow, United Kingdom
| | - Michał Czopowicz
- Laboratory of Veterinary Epidemiology and Economics, Faculty of Veterinary Medicine, Warsaw University of Life Sciences-SGGW, Warsaw, Poland
| | - Kali Lazzerini
- Small Animal Hospital, School of Veterinary Medicine, University of Glasgow, Glasgow, United Kingdom
| | - Guillaume Leblond
- Small Animal Hospital, School of Veterinary Medicine, University of Glasgow, Glasgow, United Kingdom
| | - Catherine Stalin
- Small Animal Hospital, School of Veterinary Medicine, University of Glasgow, Glasgow, United Kingdom
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Steidl E, Gleyzes M, Maddalena F, Debanne D, Buisson B. Neuroservice proconvulsive (NS-PC) set: A new platform of electrophysiology-based assays to determine the proconvulsive potential of lead compounds. J Pharmacol Toxicol Methods 2019; 99:106587. [PMID: 31207287 DOI: 10.1016/j.vascn.2019.106587] [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: 11/15/2018] [Revised: 05/17/2019] [Accepted: 05/22/2019] [Indexed: 10/26/2022]
Abstract
INTRODUCTION Failures in drug development often result from the emergence of unexpected adverse drug reactions. It is clear that adverse drug reactions, including seizure liability, should be assessed earlier. The goal of the present work was to develop a new platform of in vitro assays, NS-PC set (for Neuroservice proconvulsive set), to determine the proconvulsive potential of compounds earlier in preclinical development. METHODS Assays were based on electrophysiological recordings in acute hippocampal slices performed with multielectrode arrays. 4 reference proconvulsive/seizurogenic compounds (4-aminopyridine, bicuculline, kainate and carbachol) and 4 anti-epileptic drugs (AEDs; phenobarbital, carbamazepine, clonazepam and valproic acid) were evaluated on electrophysiological endpoints involved in seizure risk (neuronal excitability, balance of excitatory/inhibitory synaptic transmission, occurrence of neuronal synchronization mechanisms materialized by epileptiform discharges). RESULTS The reference compounds increased the number and area under the curve of population spikes, triggered epileptiform discharges and enhanced the firing rate of CA1 neurons. The effects of the 4 antiepileptic drugs were assessed on these 3 parameters. They were able to partially of completely reverse the effects of proconvulsive compounds. DISCUSSION The use of reference proconvulsive compounds and AEDs validated the electrophysiological parameters to detect proconvulsive risk. Systematic evaluation of compounds with the 3 complementary endpoints increase the probability to detect seizure liability in vitro. Depending on the compound mechanism of action, only one or two of the identified parameters might be modified.
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Affiliation(s)
- Esther Steidl
- Neuroservice SARL, 595 rue Pierre Berthier, 13593 Aix-en-Provence, France.
| | - Melanie Gleyzes
- Neuroservice SARL, 595 rue Pierre Berthier, 13593 Aix-en-Provence, France
| | - Fabien Maddalena
- Neuroservice SARL, 595 rue Pierre Berthier, 13593 Aix-en-Provence, France
| | - Dominique Debanne
- UNIS, UMR1072 INSERM - Aix-Marseille Université, 53 Bvd Pierre Dramard, 13015 Marseille, France
| | - Bruno Buisson
- Neuroservice SARL, 595 rue Pierre Berthier, 13593 Aix-en-Provence, France
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11
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Lin YT, Hsu KS. Oxytocin receptor signaling in the hippocampus: Role in regulating neuronal excitability, network oscillatory activity, synaptic plasticity and social memory. Prog Neurobiol 2018; 171:1-14. [DOI: 10.1016/j.pneurobio.2018.10.003] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2018] [Revised: 08/28/2018] [Accepted: 10/20/2018] [Indexed: 12/23/2022]
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12
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Cavarsan CF, Malheiros J, Hamani C, Najm I, Covolan L. Is Mossy Fiber Sprouting a Potential Therapeutic Target for Epilepsy? Front Neurol 2018; 9:1023. [PMID: 30555406 PMCID: PMC6284045 DOI: 10.3389/fneur.2018.01023] [Citation(s) in RCA: 50] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2018] [Accepted: 11/13/2018] [Indexed: 11/13/2022] Open
Abstract
Mesial temporal lobe epilepsy (MTLE) caused by hippocampal sclerosis is one of the most frequent focal epilepsies in adults. It is characterized by focal seizures that begin in the hippocampus, sometimes spread to the insulo-perisylvian regions and may progress to secondary generalized seizures. Morphological alterations in hippocampal sclerosis are well defined. Among them, hippocampal sclerosis is characterized by prominent cell loss in the hilus and CA1, and abnormal mossy fiber sprouting (granular cell axons) into the dentate gyrus inner molecular layer. In this review, we highlight the role of mossy fiber sprouting in seizure generation and hippocampal excitability and discuss the response of alternative treatment strategies in terms of MFS and spontaneous recurrent seizures in models of TLE (temporal lobe epilepsy).
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Affiliation(s)
- Clarissa F Cavarsan
- Department of Physiology, Universidade Federal de São Paulo, São Paulo, Brazil
| | - Jackeline Malheiros
- Department of Physiology, Universidade Federal de São Paulo, São Paulo, Brazil
| | - Clement Hamani
- Department of Physiology, Universidade Federal de São Paulo, São Paulo, Brazil.,Harquail Centre for Neuromodulation, Sunnybrook Health Sciences Centre, University of Toronto, Toronto, ON, Canada
| | - Imad Najm
- Epilepsy Center, Neurological Institute, Cleveland Clinic, Cleveland, OH, United States
| | - Luciene Covolan
- Department of Physiology, Universidade Federal de São Paulo, São Paulo, Brazil.,Epilepsy Center, Neurological Institute, Cleveland Clinic, Cleveland, OH, United States
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Guzzo EFM, Lima KR, Vargas CR, Coitinho AS. Effect of dexamethasone on seizures and inflammatory profile induced by Kindling Seizure Model. J Neuroimmunol 2018; 325:92-98. [PMID: 30316679 DOI: 10.1016/j.jneuroim.2018.10.005] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2018] [Revised: 10/04/2018] [Accepted: 10/05/2018] [Indexed: 01/16/2023]
Abstract
The objective of this study was to evaluate the effect of dexamethasone, on the severity of seizures and levels of pro-inflammatory interleukins in animals with kindling model induced by pentylenetetrazole (20 mg/kg) in alternated days for 15 days of treatment. The animals were divided into five groups: control group given saline, a group treated with diazepam (2 mg/kg) and groups treated with dexamethasone (1, 2 and 4 mg/kg). Open field test was conducted. The treatment with dexamethasone decreased the severity of seizures, also decreased TNF-alpha and Interleukin 1 beta levels in the hippocampus and TNF-alpha level in the serum.
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Affiliation(s)
- Edson Fernando Müller Guzzo
- Programa de Pós-Graduação em Farmacologia e Terapêutica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil
| | - Karina Rodrigues Lima
- Programa de Pós-Graduação em Biologia Celular e Molecular, Pontifícia Universidade Católica do Estado do Rio grande do Sul, Porto Alegre, Brazil
| | - Carmen Regla Vargas
- Programa de Pós-Graduação em Ciências Biológicas, Bioquímica, UFRGS, Rua Ramiro Barcelos, 2600, CEP 90035-003 Porto Alegre, RS, Brazil; Programa de Pós-Graduação em Ciências Farmacêuticas, UFRGS, Av. Ipiranga, 2752, CEP 90610-000 Porto Alegre, RS, Brazil; Serviço de Genética Médica, HCPA, Rua Ramiro Barcelos, 2350, CEP 90035-003 Porto Alegre, RS, Brazil; Departamento de Medicina Interna, Faculdade de Medicina, UFRGS, Brazil
| | - Adriana Simon Coitinho
- Programa de Pós-Graduação em Ciências Biológicas - Fisiologia, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil; Departamento de Microbiologia, Imunologia e Parasitologia, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil; Programa de Pós-Graduação em Farmacologia e Terapêutica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil.
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Hussain T, Kil H, Hattiangady B, Lee J, Kodali M, Shuai B, Attaluri S, Takata Y, Shen J, Abba MC, Shetty AK, Aldaz CM. Wwox deletion leads to reduced GABA-ergic inhibitory interneuron numbers and activation of microglia and astrocytes in mouse hippocampus. Neurobiol Dis 2018; 121:163-176. [PMID: 30290271 DOI: 10.1016/j.nbd.2018.09.026] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2018] [Revised: 09/18/2018] [Accepted: 09/30/2018] [Indexed: 02/07/2023] Open
Abstract
The association of WW domain-containing oxidoreductase WWOX gene loss of function with central nervous system (CNS) related pathologies is well documented. These include spinocerebellar ataxia, epilepsy and mental retardation (SCAR12, OMIM: 614322) and early infantile epileptic encephalopathy (EIEE28, OMIM: 616211) syndromes. However, there is complete lack of understanding of the pathophysiological mechanisms at play. In this study, using a Wwox knockout (Wwox KO) mouse model (2 weeks old, both sexes) and stereological studies we observe that Wwox deletion leads to a significant reduction in the number of hippocampal GABA-ergic (γ-aminobutyric acid) interneurons. Wwox KO mice displayed significantly reduced numbers of calcium-binding protein parvalbumin (PV) and neuropeptide Y (NPY) expressing interneurons in different subfields of the hippocampus in comparison to Wwox wild-type (WT) mice. We also detected decreased levels of Glutamic Acid Decarboxylase protein isoforms GAD65/67 expression in Wwox null hippocampi suggesting lower levels of GABA synthesis. In addition, Wwox deficiency was associated with signs of neuroinflammation such as evidence of activated microglia, astrogliosis, and overexpression of inflammatory cytokines Tnf-a and Il6. We also performed comparative transcriptome-wide expression analyses of neural stem cells grown as neurospheres from hippocampi of Wwox KO and WT mice thus identifying 283 genes significantly dysregulated in their expression. Functional annotation of transcriptome profiling differences identified 'neurological disease' and 'CNS development related functions' to be significantly enriched. Several epilepsy-related genes were found differentially expressed in Wwox KO neurospheres. This study provides the first genotype-phenotype observations as well as potential mechanistic clues associated with Wwox loss of function in the brain.
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Affiliation(s)
- Tabish Hussain
- Department of Epigenetics and Molecular Carcinogenesis, Science Park, The University of Texas MD Anderson Cancer Center, Smithville, TX, United States
| | - Hyunsuk Kil
- Department of Epigenetics and Molecular Carcinogenesis, Science Park, The University of Texas MD Anderson Cancer Center, Smithville, TX, United States
| | - Bharathi Hattiangady
- Institute for Regenerative Medicine, Department of Molecular and Cellular Medicine, Texas A&M Health Science Center College of Medicine, Temple and College Station, TX, United States; Research Service, Olin E. Teague Veterans' Medical Center, CTVHCS, Temple, TX, United States
| | - Jaeho Lee
- Department of Epigenetics and Molecular Carcinogenesis, Science Park, The University of Texas MD Anderson Cancer Center, Smithville, TX, United States
| | - Maheedhar Kodali
- Institute for Regenerative Medicine, Department of Molecular and Cellular Medicine, Texas A&M Health Science Center College of Medicine, Temple and College Station, TX, United States; Research Service, Olin E. Teague Veterans' Medical Center, CTVHCS, Temple, TX, United States
| | - Bing Shuai
- Institute for Regenerative Medicine, Department of Molecular and Cellular Medicine, Texas A&M Health Science Center College of Medicine, Temple and College Station, TX, United States; Research Service, Olin E. Teague Veterans' Medical Center, CTVHCS, Temple, TX, United States
| | - Sahithi Attaluri
- Institute for Regenerative Medicine, Department of Molecular and Cellular Medicine, Texas A&M Health Science Center College of Medicine, Temple and College Station, TX, United States; Research Service, Olin E. Teague Veterans' Medical Center, CTVHCS, Temple, TX, United States
| | - Yoko Takata
- Department of Epigenetics and Molecular Carcinogenesis, Science Park, The University of Texas MD Anderson Cancer Center, Smithville, TX, United States
| | - Jianjun Shen
- Department of Epigenetics and Molecular Carcinogenesis, Science Park, The University of Texas MD Anderson Cancer Center, Smithville, TX, United States
| | - Martin C Abba
- CINIBA, School of Medicine, UNLP, La Plata, Argentina
| | - Ashok K Shetty
- Institute for Regenerative Medicine, Department of Molecular and Cellular Medicine, Texas A&M Health Science Center College of Medicine, Temple and College Station, TX, United States; Research Service, Olin E. Teague Veterans' Medical Center, CTVHCS, Temple, TX, United States
| | - C Marcelo Aldaz
- Department of Epigenetics and Molecular Carcinogenesis, Science Park, The University of Texas MD Anderson Cancer Center, Smithville, TX, United States.
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Hippocampal neuropeptide Y protein expression following controlled cortical impact and posttraumatic epilepsy. Epilepsy Behav 2018; 87:188-194. [PMID: 30146352 DOI: 10.1016/j.yebeh.2018.08.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/25/2018] [Revised: 08/01/2018] [Accepted: 08/02/2018] [Indexed: 11/23/2022]
Abstract
This study assessed neuropeptide Y (NPY) expression in the hippocampus after long-term survival following traumatic brain injury (TBI) induced by controlled cortical impact (CCI) with or without the development of posttraumatic epilepsy (PTE). We hypothesized that following long-term survival after CCI, the severity of tissue injury and the development of PTE would correlate with the degree of hippocampal neurodegeneration as reflected by NPY+ and neuronal nuclear antigen (NeuN)+ cell loss. Adult Sprague-Dawley rats of 2-3 months of age were lesioned in the right parietal cortex and monitored for seizure activity by video and/or video-EEG. Neuropeptide Y and NeuN immunoreactivities (IRs) were quantified by light microscopy and semiautomatic image analysis approaches for unbiased quantification. Severely injured animals, marked by extensive tissue loss in the ipsilateral neocortex and adjacent hippocampus, resulted in significantly lower NeuN+ hilar cell density and NPY+ cell loss in the contralateral Cornu Ammonis (CA)-3 and dentate hilus (DH). The degree of NPY+ cell loss was more severe in CCI-injured animals with PTE than those animals that did not develop PTE. Mildly injured animals demonstrated no significant change of NPY expression compared with control animals. Our findings of long-term alterations of NPY expression in the hippocampus of severely brain-injured animals can provide important insights into the cellular and molecular consequences of severe TBI and posttraumatic epileptogenesis.
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Faulkner M, Hannan S, Aristovich K, Avery J, Holder D. Feasibility of imaging evoked activity throughout the rat brain using electrical impedance tomography. Neuroimage 2018; 178:1-10. [DOI: 10.1016/j.neuroimage.2018.05.022] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2018] [Revised: 04/26/2018] [Accepted: 05/08/2018] [Indexed: 10/16/2022] Open
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Ghasemi Z, Naderi N, Shojaei A, Ahmadirad N, Raoufy MR, Mirnajafi-Zadeh J. Low Frequency Electrical Stimulation Attenuated The Epileptiform Activity-Induced Changes in Action Potential Features in Hippocampal CA1 Pyramidal Neurons. CELL JOURNAL 2018; 20:355-360. [PMID: 29845789 PMCID: PMC6004994 DOI: 10.22074/cellj.2018.5443] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/17/2017] [Accepted: 09/25/2017] [Indexed: 12/19/2022]
Abstract
Objective Electrical low frequency stimulation (LFS) is a new therapeutic method that moderates hyperexcitability during epileptic states. Seizure occurrence is accompanied by some changes in action potential (AP) features. In this study, we investigated the inhibitory action of LFS on epileptiform activity (EA) induced-changes in AP features in hippocampal CA1 pyramidal neurons. Materials and Methods In this experimental study, we induced EA in hippocampal slices by increasing the extracellular potassium (K+) concentration to 12 mM. LFS (1 Hz) was applied to the Schaffer collaterals at different pulse numbers (600 and 900) at the beginning of the EA. Changes in AP features recorded by whole-cell patch clamp recording were compared using phase plot analysis. Results Induction of EA depolarized membrane potential, decreased peak amplitude, as well as the maximum rise and decay slopes of APs. Administration of 1 Hz LFS at the beginning of EA prevented the above mentioned changes in AP features. This suppressive effect of LFS depended on the LFS pulse number, such that application of 900 pulses of LFS had a stronger recovery effect on AP features that changed during EA compared to 600 pulses of LFS. The constructed phase plots of APs revealed that LFS at 900 pulses significantly decreased the changes in resting membrane potential (RMP), peak amplitude, and maximum rise and decay slopes that appeared during EA. Conclusion Increasing the numbers of LFS pulses can magnify its inhibitory effects on EA-induced changes in AP features.
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Affiliation(s)
- Zahra Ghasemi
- Department of Physiology, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran
| | - Nima Naderi
- Department of Pharmacology and Toxicology, School of Pharmacy, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Amir Shojaei
- Department of Physiology, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran
| | - Nooshin Ahmadirad
- Department of Physiology, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran
| | - Mohammad Reza Raoufy
- Department of Physiology, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran
| | - Javad Mirnajafi-Zadeh
- Department of Physiology, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran. Electronic Address:
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Wang K, Chen X, Liu J, Zou LP, Feng W, Cai L, Wu X, Chen SY. Embryonic exposure to ethanol increases the susceptibility of larval zebrafish to chemically induced seizures. Sci Rep 2018; 8:1845. [PMID: 29382872 PMCID: PMC5789864 DOI: 10.1038/s41598-018-20288-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2017] [Accepted: 01/16/2018] [Indexed: 11/27/2022] Open
Abstract
Prenatal ethanol exposure is known to cause neurodevelopmental disorders. While high prevalence of epilepsy is observed among the children whose mothers abused alcohol during pregnancy, the results from animal studies are conflicting. Here, we investigated whether embryonic exposure to ethanol can increase the susceptibility to pentylenetetrazole (PTZ)-induced seizures in larval zebrafish. Embryos at 3 hours post-fertilization (hpf) were exposed to ethanol at the concentrations ranging from 0.25% to 1% for 21 hours. Control and ethanol-exposed larvae were challenged with PTZ at 7 days post-fertilization (dpf) at the concentrations of 2.5, 5 or 15 mM. The seizure behavior of larvae was recorded and analyzed using EthoVision XT 11. We found that embryonic ethanol exposure increased the percentage of larvae exhibiting typical stage II and III seizure and resulted in a significant reduction in stage I, II and III seizure latency in an ethanol concentration-dependent manner. Embryonic exposure to ethanol also significantly increased the severity of PTZ-induced seizures in larvae, as demonstrated by increased total distance traveled and the duration of mobility. This is the first demonstration that ethanol exposure during early embryonic stage can reduce the threshold for chemically induced seizures and increase the severity of seizure behavior in larval fish.
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Affiliation(s)
- Keling Wang
- Department of Pharmacology and Toxicology, Alcohol Research Center, University of Louisville Health Science Center, Louisville, KY, 40292, USA.,Department of Pediatrics, Chinese PLA General Hospital, Beijing, 100853, China
| | - Xiaopan Chen
- Department of Pharmacology and Toxicology, Alcohol Research Center, University of Louisville Health Science Center, Louisville, KY, 40292, USA.,Department of Reproductive Endocrinology, Zhejiang Provincial People's Hospital, 158 Shangtang Road, Hangzhou, Zhejiang, 310014, China
| | - Jie Liu
- Department of Pharmacology and Toxicology, Alcohol Research Center, University of Louisville Health Science Center, Louisville, KY, 40292, USA
| | - Li-Ping Zou
- Department of Pediatrics, Chinese PLA General Hospital, Beijing, 100853, China
| | - Wenke Feng
- Department of Pharmacology and Toxicology, Alcohol Research Center, University of Louisville Health Science Center, Louisville, KY, 40292, USA.,Department of Medicine, University of Louisville, Louisville, KY, 40292, USA
| | - Lu Cai
- Pediatric Research Institute, Department of Pediatrics, University of Louisville, Louisville, KY, 40202, USA
| | - Xiaoyang Wu
- Ben May Department for Cancer Research, University of Chicago, Chicago, IL, 60637, USA
| | - Shao-Yu Chen
- Department of Pharmacology and Toxicology, Alcohol Research Center, University of Louisville Health Science Center, Louisville, KY, 40292, USA.
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Wu X, Muthuchamy M, Reddy DS. Atomic force microscopy investigations of fibronectin and α5β1-integrin signaling in neuroplasticity and seizure susceptibility in experimental epilepsy. Epilepsy Res 2017; 138:71-80. [DOI: 10.1016/j.eplepsyres.2017.10.013] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2017] [Revised: 09/15/2017] [Accepted: 10/19/2017] [Indexed: 12/15/2022]
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Seizure liability assessments using the hippocampal tissue slice: Comparison of non-clinical species. J Pharmacol Toxicol Methods 2017; 93:59-68. [PMID: 29155282 DOI: 10.1016/j.vascn.2017.11.003] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2017] [Revised: 09/29/2017] [Accepted: 11/13/2017] [Indexed: 11/22/2022]
Abstract
INTRODUCTION Traditionally, rat hippocampal tissue slice models are used as an in vitro electrophysiology assay to assess seizurogenic potential in early drug development despite non-clinical species-specific differences noted during in vivo seizure studies. METHODS Hippocampal tissue slices were acutely isolated from rats, minipigs, dogs and nonhuman primates (NHP). Population spikes (PS) were evoked through stimulation of the CA3 Schaffer collateral pathway and recorded using in vitro electrophysiological techniques via an extracellular electrode placed within the CA1 stratum pyramidale cell body layer. RESULTS Hippocampal slices, across all species, displayed a concentration-dependent increase in PS area and number with the pro-convulsant pentylenetetrazol (PTZ; 0.1-10mM). Beagle dogs exhibited higher sensitivities to PTZ-induced changes in PS area and number compared to both rats and NHPs which presented nuanced differences in their responsiveness to PTZ modulation. Minipigs were comparatively resistant to PTZ-induced changes in both PS area and number. Rat and NHP hippocampal tissues were further characterized with the pro-convulsant agents 4-aminopyradine (4-AP; 1-100μM) and cefazolin (0.001-10mM). Rats possessed higher sensitivities to 4-AP- and cefazolin-induced changes to both PS area and number whereas NHP displayed greater modulation in PS duration. The anti-convulsant agents, diazepam (10-500μM) and lidocaine (1-500μM), were also tested on either rat and/or NHP tissue with both drugs repressing PS activation at high concentrations. DISCUSSION Hippocampal tissue slices, across all species, possessed distinct sensitivities to pro- and anti-convulsant agents which may benefit the design of non-clinical seizure liability studies and their associated data interpretation.
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Erfanparast A, Tamaddonfard E, Henareh-Chareh F. Intra-hippocampal microinjection of oxytocin produced antiepileptic effect on the pentylenetetrazol-induced epilepsy in rats. Pharmacol Rep 2017; 69:757-763. [DOI: 10.1016/j.pharep.2017.03.003] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2016] [Revised: 02/11/2017] [Accepted: 03/08/2017] [Indexed: 11/28/2022]
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Xu Z, Wang Y, Chen B, Xu C, Wu X, Wang Y, Zhang S, Hu W, Wang S, Guo Y, Zhang X, Luo J, Duan S, Chen Z. Entorhinal Principal Neurons Mediate Brain-stimulation Treatments for Epilepsy. EBioMedicine 2016; 14:148-160. [PMID: 27908611 PMCID: PMC5161446 DOI: 10.1016/j.ebiom.2016.11.027] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2016] [Revised: 11/22/2016] [Accepted: 11/22/2016] [Indexed: 11/19/2022] Open
Abstract
Brain stimulation is an alternative treatment for epilepsy. However, the neuronal circuits underlying its mechanisms remain obscure. We found that optogenetic activation (1Hz) of entorhinal calcium/calmodulin-dependent protein kinase II α (CaMKIIα)-positive neurons, but not GABAergic neurons, retarded hippocampal epileptogenesis and reduced hippocampal seizure severity, similar to that of entorhinal low-frequency electrical stimulation (LFES). Optogenetic inhibition of entorhinal CaMKIIα-positive neurons blocked the antiepileptic effect of LFES. The channelrhodopsin-2-eYFP labeled entorhinal CaMKIIα-positive neurons primarily targeted the hippocampus, and the activation of these fibers reduced hippocampal seizure severity. By combining extracellular recording and pharmacological methods, we found that activating entorhinal CaMKIIα-positive neurons induced the GABA-mediated inhibition of hippocampal neurons. Optogenetic activation of focal hippocampal GABAergic neurons mimicked this neuronal modulatory effect and reduced hippocampal seizure severity, but the anti-epileptic effect is weaker than that of entorhinal LFES, which may be due to the limited spatial neuronal modulatory effect of focal photo-stimulation. Our results demonstrate a glutamatergic-GABAergic neuronal circuit for LFES treatment of epilepsy, which is mediated by entorhinal principal neurons.
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Affiliation(s)
- Zhenghao Xu
- Department of Pharmacology, Key Laboratory of Medical Neurobiology of The Ministry of Health of China, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, Zhejiang, China; Zhejiang Chinese Medical University, Hangzhou, Zhejiang, China
| | - Yi Wang
- Department of Pharmacology, Key Laboratory of Medical Neurobiology of The Ministry of Health of China, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, Zhejiang, China
| | - Bin Chen
- Department of Pharmacology, Key Laboratory of Medical Neurobiology of The Ministry of Health of China, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, Zhejiang, China
| | - Cenglin Xu
- Department of Pharmacology, Key Laboratory of Medical Neurobiology of The Ministry of Health of China, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, Zhejiang, China
| | - Xiaohua Wu
- Epilepsy Center, Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China
| | - Ying Wang
- Department of Pharmacology, Key Laboratory of Medical Neurobiology of The Ministry of Health of China, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, Zhejiang, China
| | - Shihong Zhang
- Department of Pharmacology, Key Laboratory of Medical Neurobiology of The Ministry of Health of China, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, Zhejiang, China
| | - Weiwei Hu
- Department of Pharmacology, Key Laboratory of Medical Neurobiology of The Ministry of Health of China, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, Zhejiang, China
| | - Shuang Wang
- Epilepsy Center, Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China
| | - Yi Guo
- Epilepsy Center, Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China
| | - Xiangnan Zhang
- Department of Pharmacology, Key Laboratory of Medical Neurobiology of The Ministry of Health of China, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, Zhejiang, China
| | - Jianhong Luo
- Department of Pharmacology, Key Laboratory of Medical Neurobiology of The Ministry of Health of China, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, Zhejiang, China
| | - Shumin Duan
- Department of Pharmacology, Key Laboratory of Medical Neurobiology of The Ministry of Health of China, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, Zhejiang, China
| | - Zhong Chen
- Department of Pharmacology, Key Laboratory of Medical Neurobiology of The Ministry of Health of China, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, Zhejiang, China; Epilepsy Center, Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China.
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The emerging role of in vitro electrophysiological methods in CNS safety pharmacology. J Pharmacol Toxicol Methods 2016; 81:47-59. [DOI: 10.1016/j.vascn.2016.03.008] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2016] [Revised: 03/30/2016] [Accepted: 03/30/2016] [Indexed: 01/16/2023]
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Propagating Neural Source Revealed by Doppler Shift of Population Spiking Frequency. J Neurosci 2016; 36:3495-505. [PMID: 27013678 DOI: 10.1523/jneurosci.3525-15.2016] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2015] [Accepted: 01/28/2016] [Indexed: 11/21/2022] Open
Abstract
UNLABELLED Electrical activity in the brain during normal and abnormal function is associated with propagating waves of various speeds and directions. It is unclear how both fast and slow traveling waves with sometime opposite directions can coexist in the same neural tissue. By recording population spikes simultaneously throughout the unfolded rodent hippocampus with a penetrating microelectrode array, we have shown that fast and slow waves are causally related, so a slowly moving neural source generates fast-propagating waves at ∼0.12 m/s. The source of the fast population spikes is limited in space and moving at ∼0.016 m/s based on both direct and Doppler measurements among 36 different spiking trains among eight different hippocampi. The fact that the source is itself moving can account for the surprising direction reversal of the wave. Therefore, these results indicate that a small neural focus can move and that this phenomenon could explain the apparent wave reflection at tissue edges or multiple foci observed at different locations in neural tissue. SIGNIFICANCE STATEMENT The use of novel techniques with an unfolded hippocampus and penetrating microelectrode array to record and analyze neural activity has revealed the existence of a source of neural signals that propagates throughout the hippocampus. The source itself is electrically silent, but its location can be inferred by building isochrone maps of population spikes that the source generates. The movement of the source can also be tracked by observing the Doppler frequency shift of these spikes. These results have general implications for how neural signals are generated and propagated in the hippocampus; moreover, they have important implications for the understanding of seizure generation and foci localization.
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Khom S, Hintersteiner J, Luger D, Haider M, Pototschnig G, Mihovilovic MD, Schwarzer C, Hering S. Analysis of β-Subunit-dependent GABAA Receptor Modulation and Behavioral Effects of Valerenic Acid Derivatives. J Pharmacol Exp Ther 2016; 357:580-90. [PMID: 27190170 PMCID: PMC4885513 DOI: 10.1124/jpet.116.232983] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2016] [Accepted: 04/06/2016] [Indexed: 12/30/2022] Open
Abstract
Valerenic acid (VA)-a β2/3-selective GABA type A (GABAA) receptor modulator-displays anxiolytic and anticonvulsive effects in mice devoid of sedation, making VA an interesting drug candidate. Here we analyzed β-subunit-dependent enhancement of GABA-induced chloride currents (IGABA) by a library of VA derivatives and studied their effects on pentylenetetrazole (PTZ)-induced seizure threshold and locomotion. Compound-induced IGABA enhancement was determined in oocytes expressing α1β1γ2S, α1β2γ2S, or α1β3γ2S receptors. Effects on seizure threshold and locomotion were studied using C57BL/6N mice and compared with saline-treated controls. β2/3-selective VA derivatives such as VA-amide (VA-A) modulating α1β3γ2S (VA-A: Emax = 972 ± 69%, n = 6, P < 0.05) and α1β2γ2S receptors (Emax = 1119 ± 72%, n = 6, P < 0.05) more efficaciously than VA (α1β3γ2S: VA: Emax = 632 ± 88%, n = 9 versus α1β2γ2S: VA: Emax = 721 ± 68%, n = 6) displayed significantly more pronounced seizure threshold elevation than VA (saline control: 40.4 ± 1.4 mg/kg PTZ versus VA 10 mg/kg: 49.0 ± 1.8 mg/kg PTZ versus VA-A 3 mg/kg: 57.9 ± 1.9 mg/kg PTZ, P < 0.05). Similarly, VA's methylamide (VA-MA) enhancing IGABA through β3-containing receptors more efficaciously than VA (Emax = 1043 ± 57%, P < 0.01, n = 6) displayed stronger anticonvulsive effects. Increased potency of IGABA enhancement and anticonvulsive effects at lower doses compared with VA were observed for VA-tetrazole (α1β3γ2S: VA-TET: EC50 = 6.0 ± 1.0 μM, P < 0.05; VA-TET: 0.3 mg/kg: 47.3 ± 0.5 mg/kg PTZ versus VA: 10 mg/kg: 49.0 ± 1.8 mg/kg PTZ, P < 0.05). At higher doses (≥10 mg/kg), VA-A, VA-MA, and VA-TET reduced locomotion. In contrast, unselective VA derivatives induced anticonvulsive effects only at high doses (30 mg/kg) or did not display any behavioral effects. Our data indicate that the β2/3-selective compounds VA-A, VA-MA, and VA-TET induce anticonvulsive effects at low doses (≤10 mg/kg), whereas impairment of locomotion was observed at doses ≥10 mg/kg.
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Affiliation(s)
- S Khom
- Department of Pharmacology and Toxicology, University of Vienna, Vienna, Austria (S.K., J.H., D.L., S.H.); Institute of Applied Synthetic Chemistry, TU Wien, Vienna, Austria (M.H., G.P., M.D.M.); and Department of Pharmacology, Medical University of Innsbruck, Innsbruck, Austria (C.S.)
| | - J Hintersteiner
- Department of Pharmacology and Toxicology, University of Vienna, Vienna, Austria (S.K., J.H., D.L., S.H.); Institute of Applied Synthetic Chemistry, TU Wien, Vienna, Austria (M.H., G.P., M.D.M.); and Department of Pharmacology, Medical University of Innsbruck, Innsbruck, Austria (C.S.)
| | - D Luger
- Department of Pharmacology and Toxicology, University of Vienna, Vienna, Austria (S.K., J.H., D.L., S.H.); Institute of Applied Synthetic Chemistry, TU Wien, Vienna, Austria (M.H., G.P., M.D.M.); and Department of Pharmacology, Medical University of Innsbruck, Innsbruck, Austria (C.S.)
| | - M Haider
- Department of Pharmacology and Toxicology, University of Vienna, Vienna, Austria (S.K., J.H., D.L., S.H.); Institute of Applied Synthetic Chemistry, TU Wien, Vienna, Austria (M.H., G.P., M.D.M.); and Department of Pharmacology, Medical University of Innsbruck, Innsbruck, Austria (C.S.)
| | - G Pototschnig
- Department of Pharmacology and Toxicology, University of Vienna, Vienna, Austria (S.K., J.H., D.L., S.H.); Institute of Applied Synthetic Chemistry, TU Wien, Vienna, Austria (M.H., G.P., M.D.M.); and Department of Pharmacology, Medical University of Innsbruck, Innsbruck, Austria (C.S.)
| | - M D Mihovilovic
- Department of Pharmacology and Toxicology, University of Vienna, Vienna, Austria (S.K., J.H., D.L., S.H.); Institute of Applied Synthetic Chemistry, TU Wien, Vienna, Austria (M.H., G.P., M.D.M.); and Department of Pharmacology, Medical University of Innsbruck, Innsbruck, Austria (C.S.)
| | - C Schwarzer
- Department of Pharmacology and Toxicology, University of Vienna, Vienna, Austria (S.K., J.H., D.L., S.H.); Institute of Applied Synthetic Chemistry, TU Wien, Vienna, Austria (M.H., G.P., M.D.M.); and Department of Pharmacology, Medical University of Innsbruck, Innsbruck, Austria (C.S.)
| | - S Hering
- Department of Pharmacology and Toxicology, University of Vienna, Vienna, Austria (S.K., J.H., D.L., S.H.); Institute of Applied Synthetic Chemistry, TU Wien, Vienna, Austria (M.H., G.P., M.D.M.); and Department of Pharmacology, Medical University of Innsbruck, Innsbruck, Austria (C.S.)
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Zarif H, Petit-Paitel A, Heurteaux C, Chabry J, Guyon A. TRH modulates glutamatergic synaptic inputs on CA1 neurons of the mouse hippocampus in a biphasic manner. Neuropharmacology 2016; 110:69-81. [PMID: 27060411 DOI: 10.1016/j.neuropharm.2016.04.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2015] [Revised: 03/08/2016] [Accepted: 04/05/2016] [Indexed: 11/26/2022]
Abstract
Thyrotropin Releasing Hormone (TRH) is a tripeptide that induces the release of Thyroid Stimulating Hormone (TSH) in the blood. Besides its role in the thyroid system, TRH has been shown to regulate several neuronal systems in the brain however its role in hippocampus remains controversial. Using electrophysiological recordings in acute mouse brain slices, we show that TRH depresses glutamate responses at the CA3-CA1 synapse through an action on NMDA receptors, which, as a consequence, decreases the ability of the synapse to establish a long term potentiation (LTP). TRH also induces a late increase in AMPA/kainate responses. Together, these results suggest that TRH plays an important role in the modulation of hippocampal neuronal activities, and they contribute to a better understanding of the mechanisms by which TRH impacts synaptic function underlying emotional states, learning and memory processes.
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Affiliation(s)
- Hadi Zarif
- Institut de Pharmacologie Moléculaire et Cellulaire, UMR 7275, CNRS, Université de Nice-Sophia Antipolis, F-06560, Valbonne, France
| | - Agnès Petit-Paitel
- Institut de Pharmacologie Moléculaire et Cellulaire, UMR 7275, CNRS, Université de Nice-Sophia Antipolis, F-06560, Valbonne, France
| | - Catherine Heurteaux
- Institut de Pharmacologie Moléculaire et Cellulaire, UMR 7275, CNRS, Université de Nice-Sophia Antipolis, F-06560, Valbonne, France
| | - Joëlle Chabry
- Institut de Pharmacologie Moléculaire et Cellulaire, UMR 7275, CNRS, Université de Nice-Sophia Antipolis, F-06560, Valbonne, France
| | - Alice Guyon
- Institut de Pharmacologie Moléculaire et Cellulaire, UMR 7275, CNRS, Université de Nice-Sophia Antipolis, F-06560, Valbonne, France.
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27
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Krawczyk M, Ramani M, Dian J, Florez CM, Mylvaganam S, Brien J, Reynolds J, Kapur B, Zoidl G, Poulter MO, Carlen PL. Hippocampal hyperexcitability in fetal alcohol spectrum disorder: Pathological sharp waves and excitatory/inhibitory synaptic imbalance. Exp Neurol 2016; 280:70-9. [PMID: 26996134 DOI: 10.1016/j.expneurol.2016.03.013] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2015] [Revised: 02/29/2016] [Accepted: 03/13/2016] [Indexed: 01/01/2023]
Abstract
Prenatal alcohol exposure (PAE) can lead to long-lasting neurological alterations that may predispose individuals to seizures and neurobehavioral dysfunction. To date, there exists limited information regarding the underlying pathophysiological mechanisms. The hippocampal CA3 region generates excitatory population activity, called sharp waves (SPWs), that provide an ideal model to study perturbations in neuronal excitability at the network and cellular levels. In the present study, we utilized a mouse model of PAE and used dual extracellular and whole-cell patch-clamp recordings from CA3 hippocampal pyramidal cells to evaluate the effect of 1st trimester-equivalent ethanol exposure (10% v/v) on SPW activity and excitatory/inhibitory balance. We observed that PAE significantly altered in vitro SPW waveforms, with an increased duration and amplitude, when compared to controls. In addition, PAE slices exhibited reduced pharmacological inhibition by the GABA-A receptor antagonist bicuculline (BMI) on SPW activity, and increased population spike paired-pulse ratios, all indicative of network disinhibition within the PAE hippocampus. Evaluation of PAE CA3 pyramidal cell activity associated with SPWs, revealed increased action potential cell firing, which was accompanied by an imbalance of excitatory/inhibitory synaptic drive, shifted in favor of excitation. Moreover, we observed intrinsic changes in CA3 pyramidal activity in PAE animals, including increased burst firing and instantaneous firing rate. This is the first study to provide evidence for hippocampal dysfunction in the ability to maintain network homeostasis and underlying cellular hyperexcitability in a model of PAE. These circuit and cellular level alterations may contribute to the increased propensity for seizures and neurobehavioral dysfunction observed in patients with a history of PAE.
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Affiliation(s)
- Michal Krawczyk
- Division of Fundamental Neurobiology, Toronto Western Research Institute, UHN, Toronto, ON, Canada.
| | - Meera Ramani
- Division of Fundamental Neurobiology, Toronto Western Research Institute, UHN, Toronto, ON, Canada
| | - Josh Dian
- Division of Fundamental Neurobiology, Toronto Western Research Institute, UHN, Toronto, ON, Canada
| | - Carlos M Florez
- Division of Fundamental Neurobiology, Toronto Western Research Institute, UHN, Toronto, ON, Canada
| | - Shanthini Mylvaganam
- Division of Fundamental Neurobiology, Toronto Western Research Institute, UHN, Toronto, ON, Canada
| | - James Brien
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, ON, Canada
| | - James Reynolds
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, ON, Canada
| | - Bhushan Kapur
- Division of Clinical Pharmacology & Toxicology, The Hospital for Sick Children, Toronto, ON, Canada
| | - Georg Zoidl
- Department of Biology, York University, Toronto, ON, Canada; Department of Psychology, York University, Toronto, ON, Canada
| | - Michael O Poulter
- Robarts Research Institute and Department of Physiology and Pharmacology, University of Western Ontario, London, ON, Canada
| | - Peter L Carlen
- Division of Fundamental Neurobiology, Toronto Western Research Institute, UHN, Toronto, ON, Canada; Department of Medicine (Neurology), University of Toronto, Toronto, ON, Canada; Department of Physiology, University of Toronto, Toronto, ON, Canada
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28
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Immunohistochemical evaluation of hippocampal CA1 region astrocytes in 10-day-old rats after monosodium glutamate treatment. Pol J Vet Sci 2015; 18:767-74. [DOI: 10.1515/pjvs-2015-0099] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Abstract
High concentration of glutamate (Glu) is excitotoxic for nervous system structures. This may lead to glial reactivity ie. increased expression of glial fibrillary acidic protein (GFAP) and S100β protein, and also to hypertrophy and proliferation of cells which are determined by the presence of Ki-67 antigen. The aim of the study was to analyse the immunoreactivity of the GFAP, S100β and Ki-67 proteins in astrocytes of hippocampal CA1 region in young rats after administration of monosodium glutamate (MSG) at two doses: 2 g/kg b.w. (I group) and 4 g/kg b.w. (II group). In rats from I and II group morphologically altered astrocytes with the GFAP expression were observed in the SLM of the hippocampal CA1 region. The cells had eccentrically located nuclei and on the opposite site of the nuclei there were single or double, long and weakly branched processes. Moreover, in the SLM the increase of the number of GFAP and S100β immunopositive astrocytes and nuclei with Ki-67 expression, in contrary to control individuals, was observed. These results suggest the increased expression of the proteins in early reactions or hyperplasia which, together with cell hypertrophy, indicate late reactivity of astroglia in response to glutamate noxious effect.
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29
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Lin CH, Yang CT, Tsai MC, Wu YT, MacDonald I, Wang ML, Wu CH, Leung YM, Chen YH. (±)3,4-Methylenedioxyamphetamine inhibits the TEA-sensitive K+ current in the hippocampal neuron and the Kv2.1 current expressed in H1355 cells. Neuropharmacology 2015; 89:100-12. [DOI: 10.1016/j.neuropharm.2014.09.009] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2013] [Revised: 08/20/2014] [Accepted: 09/04/2014] [Indexed: 10/24/2022]
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30
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Fonck C, Easter A, Pietras MR, Bialecki RA. CNS Adverse Effects: From Functional Observation Battery/Irwin Tests to Electrophysiology. Handb Exp Pharmacol 2015; 229:83-113. [PMID: 26091637 DOI: 10.1007/978-3-662-46943-9_4] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
This chapter describes various approaches for the preclinical assessment of drug-induced central nervous system (CNS) adverse effects. Traditionally, methods to evaluate CNS effects have consisted of observing and scoring behavioral responses of animals after drug is administered. Among several behavioral testing paradigms, the Irwin and the functional observational battery (FOB) are the most commonly used assays for the assessment of CNS effects. The Irwin and FOB are considered good first-tier assays to satisfy the ICH S7A guidance for the preclinical evaluation of new chemical entities (NCE) intended for humans. However, experts have expressed concern about the subjectivity and lack of quantitation that is derived from behavioral testing. More importantly, it is difficult to gain insight into potential mechanisms of toxicity by assessing behavioral outcomes. As a complement to behavioral testing, we propose using electrophysiology-based assays, both in vivo and in vitro, such as electroencephalograms and brain slice field-potential recordings. To better illustrate these approaches, we discuss the implementation of electrophysiology-based techniques in drug-induced assessment of seizure risk, sleep disruption, and cognitive impairment.
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Affiliation(s)
- Carlos Fonck
- Global Safety Pharmacology, AstraZeneca Pharmaceuticals LP, 35 Gatehouse Drive, Waltham, MA, 02451, USA
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31
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Isaeva E, Romanov A, Holmes GL, Isaev D. Status epilepticus results in region-specific alterations in seizure susceptibility along the hippocampal longitudinal axis. Epilepsy Res 2014; 110:166-70. [PMID: 25616469 DOI: 10.1016/j.eplepsyres.2014.12.009] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2014] [Revised: 11/23/2014] [Accepted: 12/08/2014] [Indexed: 11/19/2022]
Abstract
Temporal lobe epilepsy (TLE) is the most common epilepsy syndrome in adults. In particular, the hippocampus is highly susceptible to abnormal synchronization. Recent advances in the surgical treatment of patients with refractory TLE have shown that multiple hippocampal transections can effectively control seizures. It has been suggested that in TLE the synchrony in the longitudinal connections is required for seizure generation; however the physiological background for the increase in hippocampal synchronization along the longitudinal axis is not fully understood. The hippocampus varies in seizure susceptibility along its longitudinal axis with the ventral hippocampus (VH) region being more seizure-prone and susceptible to neuronal damage than the dorsal hippocampus (DH). In the present study we studied seizure susceptibility along the longitudinal axis of the hippocampus following pilocarpine-induced status epilepticus (SE). In control conditions the VH generates epileptiform activity (EA) more frequently than the DH when exposed to a low Mg(2+)/1Ca(2+)/5K(+) solution. Following SE the probability of inducing epileptiform activity (EA) is similar in the VH and DH slices. This SE-induced change is due to an increase in the proportion of DH slices responding to the low Mg(2+)/1Ca(2+)/5K(+) solution with EA. Moreover, both the VH and DH show similar responses to a low Mg(2+)/1Ca(2+)/5K(+) solution. These findings indicate that the hippocampus undergoes significant functional changes following SE, which may provide the necessary increase of synchrony along the longitudinal axis to generate seizures in TLE.
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Affiliation(s)
- Elena Isaeva
- Department of Neurological Sciences, University of Vermont College of Medicine, Burlington, VT, USA; Department of Cellular Membranology, Bogomoletz Institute of Physiology, Kiev, Ukraine.
| | - Arthur Romanov
- Department of Cellular Membranology, Bogomoletz Institute of Physiology, Kiev, Ukraine
| | - Gregory L Holmes
- Department of Neurological Sciences, University of Vermont College of Medicine, Burlington, VT, USA
| | - Dmytro Isaev
- Department of Neurological Sciences, University of Vermont College of Medicine, Burlington, VT, USA; Department of Cellular Membranology, Bogomoletz Institute of Physiology, Kiev, Ukraine
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32
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Ding J, Huang C, Peng Z, Xie Y, Deng S, Nie YZ, Xu TL, Ge WH, Li WG, Li F. Electrophysiological characterization of methyleugenol: a novel agonist of GABA(A) receptors. ACS Chem Neurosci 2014; 5:803-11. [PMID: 24980777 DOI: 10.1021/cn500022e] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Methyleugenol (ME) is a natural constituent isolated from many plant essential oils having multiple biological effects including anticonvulsant and anesthetic activities, although the underlying mechanisms remain unclear. Here, we identify ME as a novel agonist of ionotropic γ-aminobutyric acid (GABA) receptors. At lower concentrations (∼30 μM), ME significantly sensitized GABA-induced, but not glutamate- or glycine-induced, currents in cultured hippocampal neurons, indicative of a preferentially modulatory role of this compound for A type GABA receptors (GABAARs). In addition, ME at higher concentrations (≥100 μM) induced a concentration-dependent, Cl(-)-permeable current in hippocampal neurons, which was inhibited by a GABAAR channel blocker, picrotoxin, and a competitive GABAAR antagonist, bicuculline, but not a specific glycine receptor inhibitor, strychnine. Moreover, ME activated a similar current mediated by recombinant α1-β2-γ2 or α5-β2-γ2 GABAARs in human embryonic kidney (HEK) cells. Consequently, ME produced a strong inhibition of synaptically driven neuronal excitation in hippocampal neurons. Together, these results suggest that ME represents a novel agonist of GABAARs, shedding additional light on future development of new therapeutics targeting GABAARs. The present study also adds GABAAR activation to the list of molecular targets of ME that probably account for its biological activities.
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Affiliation(s)
- Jing Ding
- Department
of Developmental and Behavioral Pediatrics, Shanghai Institute of
Pediatric Translational Medicine, Shanghai Children’s Medical
Center, Ministry of Education-Shanghai Key Laboratory of Children’s
Environmental Health, Shanghai Jiao Tong University School of Medicine, Shanghai 200129, China
- Department
of Chinese Materia Medica, College of Pharmaceutical Science, Zhejiang Chinese Medical University, Hangzhou 310053, China
- Neuroscience
Division, Departments of Anatomy, Histology and Embryology, Biochemistry,
and Molecular Cell Biology, Shanghai Key Laboratory for Tumor Microenvironment
and Inflammation, Institute of Medical Sciences, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Chen Huang
- Neuroscience
Division, Departments of Anatomy, Histology and Embryology, Biochemistry,
and Molecular Cell Biology, Shanghai Key Laboratory for Tumor Microenvironment
and Inflammation, Institute of Medical Sciences, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Zhong Peng
- Neuroscience
Division, Departments of Anatomy, Histology and Embryology, Biochemistry,
and Molecular Cell Biology, Shanghai Key Laboratory for Tumor Microenvironment
and Inflammation, Institute of Medical Sciences, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Yuxuan Xie
- Department
of Developmental and Behavioral Pediatrics, Shanghai Institute of
Pediatric Translational Medicine, Shanghai Children’s Medical
Center, Ministry of Education-Shanghai Key Laboratory of Children’s
Environmental Health, Shanghai Jiao Tong University School of Medicine, Shanghai 200129, China
| | - Shining Deng
- Department
of Developmental and Behavioral Pediatrics, Shanghai Institute of
Pediatric Translational Medicine, Shanghai Children’s Medical
Center, Ministry of Education-Shanghai Key Laboratory of Children’s
Environmental Health, Shanghai Jiao Tong University School of Medicine, Shanghai 200129, China
| | - Yan-Zhen Nie
- Department
of Developmental and Behavioral Pediatrics, Shanghai Institute of
Pediatric Translational Medicine, Shanghai Children’s Medical
Center, Ministry of Education-Shanghai Key Laboratory of Children’s
Environmental Health, Shanghai Jiao Tong University School of Medicine, Shanghai 200129, China
| | - Tian-Le Xu
- Neuroscience
Division, Departments of Anatomy, Histology and Embryology, Biochemistry,
and Molecular Cell Biology, Shanghai Key Laboratory for Tumor Microenvironment
and Inflammation, Institute of Medical Sciences, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Wei-Hong Ge
- Department
of Chinese Materia Medica, College of Pharmaceutical Science, Zhejiang Chinese Medical University, Hangzhou 310053, China
| | - Wei-Guang Li
- Department
of Developmental and Behavioral Pediatrics, Shanghai Institute of
Pediatric Translational Medicine, Shanghai Children’s Medical
Center, Ministry of Education-Shanghai Key Laboratory of Children’s
Environmental Health, Shanghai Jiao Tong University School of Medicine, Shanghai 200129, China
- Neuroscience
Division, Departments of Anatomy, Histology and Embryology, Biochemistry,
and Molecular Cell Biology, Shanghai Key Laboratory for Tumor Microenvironment
and Inflammation, Institute of Medical Sciences, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Fei Li
- Department
of Developmental and Behavioral Pediatrics, Shanghai Institute of
Pediatric Translational Medicine, Shanghai Children’s Medical
Center, Ministry of Education-Shanghai Key Laboratory of Children’s
Environmental Health, Shanghai Jiao Tong University School of Medicine, Shanghai 200129, China
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Hyaluronan deficiency due to Has3 knock-out causes altered neuronal activity and seizures via reduction in brain extracellular space. J Neurosci 2014; 34:6164-76. [PMID: 24790187 DOI: 10.1523/jneurosci.3458-13.2014] [Citation(s) in RCA: 103] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Hyaluronan (HA), a large anionic polysaccharide (glycosaminoglycan), is a major constituent of the extracellular matrix of the adult brain. To address its function, we examined the neurophysiology of knock-out mice deficient in hyaluronan synthase (Has) genes. Here we report that these Has mutant mice are prone to epileptic seizures, and that in Has3(-/-) mice, this phenotype is likely derived from a reduction in the size of the brain extracellular space (ECS). Among the three Has knock-out models, namely Has3(-/-), Has1(-/-), and Has2(CKO), the seizures were most prevalent in Has3(-/-) mice, which also showed the greatest HA reduction in the hippocampus. Electrophysiology in Has3(-/-) brain slices demonstrated spontaneous epileptiform activity in CA1 pyramidal neurons, while histological analysis revealed an increase in cell packing in the CA1 stratum pyramidale. Imaging of the diffusion of a fluorescent marker revealed that the transit of molecules through the ECS of this layer was reduced. Quantitative analysis of ECS by the real-time iontophoretic method demonstrated that ECS volume was selectively reduced in the stratum pyramidale by ∼ 40% in Has3(-/-) mice. Finally, osmotic manipulation experiments in brain slices from Has3(-/-) and wild-type mice provided evidence for a causal link between ECS volume and epileptiform activity. Our results provide the first direct evidence for the physiological role of HA in the regulation of ECS volume, and suggest that HA-based preservation of ECS volume may offer a novel avenue for development of antiepileptogenic treatments.
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Ebrahimi L, Saboory E, Roshan-Milani S, Hashemi P. Effect of prenatal forced-swim stress and morphine co-administration on pentylentetrazol-induced epileptic behaviors in infant and prepubertal rats. Dev Psychobiol 2014; 56:1179-86. [PMID: 24464467 DOI: 10.1002/dev.21198] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2013] [Accepted: 12/17/2013] [Indexed: 11/11/2022]
Abstract
Prenatal exposure to stress and morphine has complicated effects on epileptic seizure. Many reports have shown an interaction between morphine- and stress-induced behavioral changes in adult rats. In the present study, effect of prenatal forced-swim stress and morphine co-administration on pentylentetrazole (PTZ)-induced epileptic behaviors was investigated in rat offspring to address effect of the interaction between morphine and stress. Pregnant rats were divided to four groups of control-saline, control-morphine, stressed-saline and stressed-morphine. In the stressed group, the rats were placed in 25 °C water on 17-19 days of pregnancy. In the morphine/saline group, the rats received morphine/saline on the same days. In the morphine/saline-stressed group, they were exposed to stress and received morphine/saline simultaneously. On postnatal day 15 (P15), blood samples were collected to determine corticosterone (COS) level. On P15 and P25, PTZ was injected to the rest of pups to induce seizure. Then, epileptic behaviors of each rat were individually observed. Latency of tonic-colonic seizures decreased in control-morphine and stressed-saline groups while increasing in stressed-morphine rats compared to control-saline group on P15. Duration of tonic-colonic seizures significantly increased in control-morphine and stressed-saline rats compared to stressed-morphine and control-saline rats on P15, but not P25. COS levels increased in stressed-saline group but decreased in control-morphine group compared to control-saline rats. Body weight was significantly higher in morphine groups than saline treated rats. Prenatal exposure to forced-swim stress potentiated PTZ-induced seizure in the offspring rats. Co-administration of morphine attenuated effect of stress on body weight, COS levels, and epileptic behaviors.
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Affiliation(s)
- Loghman Ebrahimi
- Department of Physiology, Faculty of Medicine, Urmia University of Medical Sciences, Urmia, Iran
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35
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Buckmaster PS. Does mossy fiber sprouting give rise to the epileptic state? ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2014; 813:161-8. [PMID: 25012375 DOI: 10.1007/978-94-017-8914-1_13] [Citation(s) in RCA: 63] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Many patients with temporal lobe epilepsy display structural changes in the seizure initiating zone, which includes the hippocampus. Structural changes in the hippocampus include granule cell axon (mossy fiber) sprouting. The role of mossy fiber sprouting in epileptogenesis is controversial. A popular view of temporal lobe epileptogenesis contends that precipitating brain insults trigger transient cascades of molecular and cellular events that permanently enhance excitability of neuronal networks through mechanisms including mossy fiber sprouting. However, recent evidence suggests there is no critical period for mossy fiber sprouting after an epileptogenic brain injury. Instead, findings from stereological electron microscopy and rapamycin-delayed mossy fiber sprouting in rodent models of temporal lobe epilepsy suggest a persistent, homeostatic mechanism exists to maintain a set level of excitatory synaptic input to granule cells. If so, a target level of mossy fiber sprouting might be determined shortly after a brain injury and then remain constant. Despite the static appearance of synaptic reorganization after its development, work by other investigators suggests there might be continual turnover of sprouted mossy fibers in epileptic patients and animal models. If so, there may be opportunities to reverse established mossy fiber sprouting. However, reversal of mossy fiber sprouting is unlikely to be antiepileptogenic, because blocking its development does not reduce seizure frequency in pilocarpine-treated mice. The challenge remains to identify which, if any, of the many other structural changes in the hippocampus are epileptogenic.
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Affiliation(s)
- Paul S Buckmaster
- Departments of Comparative Medicine and Neurology & Neurological Sciences, Stanford University, Stanford, CA, USA,
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36
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Saboory E, Gholami M, Zare S, Roshan-Milani S. The long-term effects of neonatal morphine administration on the pentylenetetrazol seizure model in rats: the role of hippocampal cholinergic receptors in adulthood. Dev Psychobiol 2013; 56:498-509. [PMID: 23775703 DOI: 10.1002/dev.21117] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2012] [Accepted: 03/04/2013] [Indexed: 11/07/2022]
Abstract
Early life exposure to opiates may affect neuropathological conditions, such as epilepsy, during adulthood. We investigated whether neonatal morphine exposure affects pentylenetetrazol (PTZ)-induced seizures in adulthood. Male rats were subcutaneously injected with morphine or saline on postnatal days 8-14. During adulthood, each rat was assigned to 1 of the following 10 sub-groups: saline, nicotine (0.1, 0.5, or 1 μg), atropine (0.25 or 1 μg), oxotremorine M (0.1 or 1 μg), or mecamylamine (2 or 8 μg). An intrahippocampal infusion of the indicated compound was administered 30 min before seizure induction (80 mg/kg PTZ). Compared with the saline/oxotremorine (1 μg), saline/saline, and morphine/saline groups, the morphine/oxotremorine (1 μg) group showed a significantly increased latency to the first epileptic behavior. The duration of tonic-clonic seizures was significantly lower in the morphine/oxotremorine (1 μg) group compared to the saline/saline and morphine/saline groups. The severity of seizure was significantly decreased in the morphine/atropine (1 μg) group than in the saline/atropine (1 μg). Seizure severity was also decreased in the morphine/mecamylamine (2 μg) group than in the saline/mecamylamine (2 μg) group. Latency for death was significantly lower in the morphine/mecamylamine (2 μg) group compared with the saline/mecamylamine (2 μg) group. Mortality rates in the morphine/atropine (1 μg) and morphine/mecamylamine (2 μg) groups were significantly lower than those in the saline/atropine (1 μg) and saline/mecamylamine (2 μg) groups, respectively. Chronic neonatal morphine administration attenuated PTZ-induced seizures, reduced the mortality rate, and decreased the impact of the hippocampal cholinergic system on seizures and mortality rate in adult rats. Neonatal morphine exposure induces changes to μ-receptors that may lead to activation of GABAergic neurons in the hippocampus. This pathway may explain the anti-convulsant effects of morphine observed in our study.
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Affiliation(s)
- Ehsan Saboory
- Faculty of Medicine, Department of Physiology, Neurophysiology Research Center, Urmia University of Medical Sciences, Urmia, Iran
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37
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Gholami M, Saboory E, Zare S, Roshan-Milani S, Hajizadeh-Moghaddam A. The effect of dorsal hippocampal administration of nicotinic and muscarinic cholinergic ligands on pentylenetetrazol-induced generalized seizures in rats. Epilepsy Behav 2012; 25:244-9. [PMID: 23037131 DOI: 10.1016/j.yebeh.2012.07.004] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/18/2012] [Revised: 07/06/2012] [Accepted: 07/09/2012] [Indexed: 11/30/2022]
Abstract
In the present study, the effects of intrahippocampal injections of cholinergic ligands on pentylenetetrazol (PTZ)-induced seizures were investigated in rats. The rats were assigned to 1 of the following 9 groups: saline, nicotine (0.5 or 1 μg), atropine (0.25 or 1 μg), oxotremorine-M (0.1 or 1 μg), or mecamylamine (2 or 8 μg). Cholinergic ligands were administered via intrahippocampal infusion 30 min before seizure induction (intraperitoneal injection of 80 mg/kg PTZ). Results show that antagonists caused nonsignificant increases in the latency of tonic-clonic seizures, significant decreases in the duration of tonic-clonic seizures, significant decreases in the latency of death, and increases in mortality rate. Agonists led to increases in the duration of tonic-clonic seizures, decreases in the latency of death, and decreases in mortality rate. These results provide compelling evidence that cholinergic ligands show modulatory effects on a PTZ model of acute seizure in the rat hippocampus.
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Affiliation(s)
- Morteza Gholami
- Master in Physiology, Department of Biology, Faculty of Science, University of Urmia, Iran.
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Maleki N, Becerra L, Brawn J, McEwen B, Burstein R, Borsook D. Common hippocampal structural and functional changes in migraine. Brain Struct Funct 2012; 218:903-12. [PMID: 22760159 DOI: 10.1007/s00429-012-0437-y] [Citation(s) in RCA: 122] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2011] [Accepted: 06/09/2012] [Indexed: 11/29/2022]
Abstract
The hippocampus is classically involved in memory consolidation, spatial navigation and is involved in the stress response. Migraine is an episodic disorder characterized by intermittent attacks with a number of physiological and emotional stressors associated with or provoking each attack. Given that migraine attacks can be viewed as repeated stressors, alterations in hippocampal function and structure may play an important role in migraine pathophysiology. Using high-resolution magnetic resonance imaging, hippocampal morphometric and functional differences (in response to noxious heat stimulation) were compared in age and gender-matched acute episodic migraineurs with high (HF) versus low (LF) frequency of migraine attacks. Morphometric results were compared with age and gender-matched healthy control (HC) cohort. Significant larger bilateral hippocampal volume was found in LF group relative to the HF and HC groups suggestive of an initial adaptive plasticity that may then become dysfunctional with increased frequency. Functional correlates of greater deactivation (LF > HF) in the same hippocampal regions in response to noxious stimulation was also accompanied by overall reduction in functional connectivity of the hippocampus with other brain regions involved in pain processing in the HF group. The results implicate involvement of hippocampus in the pathophysiology of the migraine.
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Affiliation(s)
- Nasim Maleki
- Department of Anesthesia and Radiology, Center for Pain and the Brain, MCL, MGH and CHB, Children's Hospital Boston and Harvard Medical School, Boston, MA, USA
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Holt AB, Netoff TI. Computational modeling of epilepsy for an experimental neurologist. Exp Neurol 2012; 244:75-86. [PMID: 22617489 DOI: 10.1016/j.expneurol.2012.05.003] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2012] [Revised: 04/27/2012] [Accepted: 05/05/2012] [Indexed: 10/28/2022]
Abstract
Computational modeling can be a powerful tool for an experimentalist, providing a rigorous mathematical model of the system you are studying. This can be valuable in testing your hypotheses and developing experimental protocols prior to experimenting. This paper reviews models of seizures and epilepsy at different scales, including cellular, network, cortical region, and brain scales by looking at how they have been used in conjunction with experimental data. At each scale, models with different levels of abstraction, the extraction of physiological detail, are presented. Varying levels of detail are necessary in different situations. Physiologically realistic models are valuable surrogates for experimental systems because, unlike in an experiment, every parameter can be changed and every variable can be observed. Abstract models are useful in determining essential parameters of a system, allowing the experimentalist to extract principles that explain the relationship between mechanisms and the behavior of the system. Modeling is becoming easier with the emergence of platforms dedicated to neuronal modeling and databases of models that can be downloaded. Modeling will never be a replacement for animal and clinical experiments, but it should be a starting point in designing experiments and understanding their results.
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Affiliation(s)
- Abbey B Holt
- Dept. of Neuroscience, University of Minnesota, Minneapolis, MN 55455, USA
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Wu X, Reddy DS. Integrins as receptor targets for neurological disorders. Pharmacol Ther 2011; 134:68-81. [PMID: 22233753 DOI: 10.1016/j.pharmthera.2011.12.008] [Citation(s) in RCA: 113] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2011] [Accepted: 12/15/2011] [Indexed: 12/18/2022]
Abstract
This review focuses on the neurobiology of integrins, pathophysiological roles of integrins in neuroplasticity and nervous system disorders, and therapeutic implications of integrins as potential drug targets and possible delivery pathways. Neuroplasticity is a central phenomenon in many neurological conditions such as seizures, trauma, and traumatic brain injury. During the course of many brain diseases, in addition to intracellular compartment changes, alterations in non-cell compartments such as extracellular matrix (ECM) are recognized as an essential process in forming and reorganizing neural connections. Integrins are heterodimeric transmembrane receptors that mediate cell-ECM and cell-cell adhesion events. Although the mechanisms of neuroplasticity remain unclear, it has been suggested that integrins undergo plasticity including clustering through interactions with ECM proteins, modulating ion channels, intracellular Ca(2+) and protein kinase signaling, and reorganization of cytoskeletal filaments. As cell surface receptors, integrins are central to the pathophysiology of many brain diseases, such as epilepsy, and are potential targets for the development of new drugs for neurological disorders.
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Affiliation(s)
- Xin Wu
- Department of Neuroscience and Experimental Therapeutics, Texas A&M Health Science Center College of Medicine, Bryan, TX 77807, USA
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Lalic T, Pettingill P, Vincent A, Capogna M. Human limbic encephalitis serum enhances hippocampal mossy fiber-CA3 pyramidal cell synaptic transmission. Epilepsia 2010; 52:121-31. [DOI: 10.1111/j.1528-1167.2010.02756.x] [Citation(s) in RCA: 88] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
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Frey JU. Continuous blockade of GABA-ergic inhibition induces novel forms of long-lasting plastic changes in apical dendrites of the hippocampal cornu ammonis 1 (CA1) in vitro. Neuroscience 2009; 165:188-97. [PMID: 19837134 DOI: 10.1016/j.neuroscience.2009.10.015] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2009] [Revised: 10/06/2009] [Accepted: 10/09/2009] [Indexed: 10/20/2022]
Abstract
Hippocampal long-term potentiation (LTP) is considered as a fundamental mechanism for learning and memory formation. A role for GABA was reported for the induction and early but not late maintenance of LTP. We have now investigated whether GABA-receptor function is involved in the prolonged maintenance of LTP (>4 h) at afferent synapses at apical dendrites of cornu ammonis 1 (CA1)-pyramidal neurons in hippocampal slices in vitro. Our data demonstrate that GABA-receptor mediated events are not required for conventional, tetanically-induced early- or late-LTP in the hippocampal CA1-region in vitro. Inhibition of GABA-ergic transmission did not negatively influence either early- or late-LTP. In contrast, an additional facilitation was observed at time points corresponding to the establishment of late-LTP (after 3-4 h). Investigation of a second, non-tetanized control input to the same neuronal population revealed that the elevated potentiation of late-LTP in the tetanized input was not LTP-specific. Therefore, we have examined, whether continuous application of GABA-receptor inhibitors also affected the time course of the recorded potentials when a low-frequency stimulation protocol was used. Under these conditions two distinct forms of a late-onset potentiation occurred 5-6 h after drug application. Investigation of mechanisms responsible for this prolonged enhancement of potentials revealed that the higher form of potentiation (potentiation levels above 200%) was dependent on presynaptic activity and N-methyl-d-aspartate (NMDA)-receptor activation, whereas the lower form (potentiation less than 200%) did not require these mechanisms. However, the latter potentiation was prevented by nifedipine, an L-type voltage-dependent calcium channel inhibitor.
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Affiliation(s)
- J U Frey
- Leibniz Institute for Neurobiology, Department of Neurophysiology, Magdeburg, Germany.
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Easter A, Bell ME, Damewood JR, Redfern WS, Valentin JP, Winter MJ, Fonck C, Bialecki RA. Approaches to seizure risk assessment in preclinical drug discovery. Drug Discov Today 2009; 14:876-84. [PMID: 19545644 DOI: 10.1016/j.drudis.2009.06.003] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2009] [Revised: 06/09/2009] [Accepted: 06/10/2009] [Indexed: 01/01/2023]
Abstract
Assessment of seizure risk traditionally occurs late in the drug discovery process using low-throughput, resource intensive in vivo assays. Such approaches do not allow sufficient time to mitigate risk by influencing chemical design. Early identification using cheaper, higher throughput assays with lower animal and compound requirements would be preferable. Here we review the current techniques available to assess this issue and describe how they may be combined in a rational step-wise cascade allowing more effective assessment of seizure risk.
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Affiliation(s)
- Alison Easter
- Safety Assessment US, AstraZeneca R&D Wilmington, DE 19850, USA.
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Lively S, Brown IR. Extracellular matrix protein SC1/hevin in the hippocampus following pilocarpine-induced status epilepticus. J Neurochem 2008; 107:1335-46. [PMID: 18808451 DOI: 10.1111/j.1471-4159.2008.05696.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Pilocarpine-induced status epilepticus (SE) mimics many features of temporal lobe epilepsy and is a useful model to study neural changes that result from prolonged seizure activity. In this study, distribution of the anti-adhesive extracellular matrix protein SC1 was examined in the rat hippocampus following SE. Western blotting showed decreased levels of SC1 protein in the week following SE. Immunohistochemistry demonstrated that the decrease in overall SC1 protein levels was reflected by a reduction of SC1 signal in granule cells of the dentate gyrus. Interestingly, levels of SC1 protein in neurons of the seizure-resistant CA2 sector of the hippocampus did not change throughout the seizure time course. However, at 1 day post-SE, a subset of neurons of the hippocampal CA1, CA3, and hilar regions, which are noted for extensive neuronal degeneration after SE, exhibited a transient increase in SC1 signal. Neurons exhibiting enhanced SC1 signal were not detected at 7 days post-SE. The cellular stress response was also examined. A prominent induction of heat-shock protein (Hsp70) and Hsp27 was detected following SE, while levels of constitutively expressed Hsp40, Hsp90, Hsp110, and Hsc70 showed little change at the time points examined. The subset of neurons that demonstrated a transient increase in SC1 colocalized with the cellular stress marker Hsp70, the degeneration marker Fluoro-Jade B, and the neuron activity marker activity-regulated cytoskeleton-associated protein (Arc). Taken together, these findings suggest that SC1 may be a component of the 'matrix response' involved in remodeling events associated with neuronal degeneration following neural injury.
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Affiliation(s)
- Starlee Lively
- Center for the Neurobiology of Stress, University of Toronto at Scarborough, Toronto, Ontario, Canada
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Functional significance of axonal Kv7 channels in hippocampal pyramidal neurons. Proc Natl Acad Sci U S A 2008; 105:7869-74. [PMID: 18515424 DOI: 10.1073/pnas.0802805105] [Citation(s) in RCA: 198] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Members of the Kv7 family (Kv7.2-Kv7.5) generate a subthreshold K(+) current, the M- current. This regulates the excitability of many peripheral and central neurons. Recent evidence shows that Kv7.2 and Kv7.3 subunits are targeted to the axon initial segment of hippocampal neurons by association with ankyrin G. Further, spontaneous mutations in these subunits that impair axonal targeting cause human neonatal epilepsy. However, the precise functional significance of their axonal location is unknown. Using electrophysiological techniques together with a peptide that selectively disrupts axonal Kv7 targeting (ankyrin G-binding peptide, or ABP) and other pharmacological tools, we show that axonal Kv7 channels are critically and uniquely required for determining the inherent spontaneous firing of hippocampal CA1 pyramids, independently of alterations in synaptic activity. This action was primarily because of modulation of action potential threshold and resting membrane potential (RMP), amplified by control of intrinsic axosomatic membrane properties. Computer simulations verified these data when the axonal Kv7 density was three to five times that at the soma. The increased firing caused by axosomatic Kv7 channel block backpropagated into distal dendrites affecting their activity, despite these structures having fewer functional Kv7 channels. These results indicate that axonal Kv7 channels, by controlling axonal RMP and action potential threshold, are fundamental for regulating the inherent firing properties of CA1 hippocampal neurons.
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Ogawa S, Kwon CH, Zhou J, Koovakkattu D, Parada LF, Sinton CM. A seizure-prone phenotype is associated with altered free-running rhythm in Pten mutant mice. Brain Res 2007; 1168:112-23. [PMID: 17706614 DOI: 10.1016/j.brainres.2007.06.074] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2007] [Revised: 06/08/2007] [Accepted: 06/15/2007] [Indexed: 01/16/2023]
Abstract
Conditional deletion of Pten (phosphatase and tensin homolog on chromosome ten) in differentiated cortical and hippocampal neurons in the mouse results in seizures, macrocephaly, social interaction deficits and anxiety, reminiscent of human autism spectrum disorder. Here we extended our previous examination of these mice using electroencephalogram/electromyogram (EEG/EMG) monitoring and found age-related increases in spontaneous seizures, which were correlated with cellular dispersion in the hippocampal dentate gyrus. Increased spontaneous locomotor activity in the open field on the first and the second day of a 3-day continuous study suggested heightened anxiety in Pten mutant mice. In contrast, the mutants exhibited decreased wheel running activity, which may reflect reduced adaptability to a novel environment. Synchronization to the light-dark cycle was normal, but for up to 28 days under constant darkness, the Pten mutants maintained a significantly lengthened and remarkably constant free-running period of almost exactly 24 h. This result implies the involvement of Pten in the maintenance of circadian rhythms, which we interpret as being due to an effect on the phosphatidylinositol 3-kinase (PI3K) signaling cascade.
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Affiliation(s)
- Shiori Ogawa
- Department of Internal Medicine, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75390, USA
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Easter A, Sharp TH, Valentin JP, Pollard CE. Pharmacological validation of a semi-automated in vitro hippocampal brain slice assay for assessment of seizure liability. J Pharmacol Toxicol Methods 2007; 56:223-33. [PMID: 17600733 DOI: 10.1016/j.vascn.2007.04.008] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2007] [Accepted: 04/16/2007] [Indexed: 12/22/2022]
Abstract
INTRODUCTION Drug-induced seizures are a serious, life-threatening adverse drug reaction (ADR) that can result in the failure of drugs to be licensed for clinical use or withdrawn from the market. Seizure liability of potential drugs is traditionally assessed using animal models run during the later phases of the drug discovery process. Given the low throughput, high animal usage and high compound requirement associated with these assays, it would be advantageous to identify higher throughput, in vitro models that could be used to give an earlier assessment of seizure liability. The hippocampal brain slice is one possibility but conventionally allows recording from only one slice at a time. The aim of this study was to validate a semi-automated system (Slicemaster, Scientifica UK Ltd) which allows concurrent electrophysiological recording from multiple brain slices. METHODS Conventional electrophysiological recording techniques were used to record electrically evoked synaptic activity from rat hippocampal brain slices. Population spikes (PS) were evoked at 30 s intervals by electrical stimulation of the Schaffer collateral pathway and were recorded using extracellular electrodes positioned in the CA1 cell body layer. Responses were quantified as PS areas (the area above and below the 0 mV line). The effects of eight validation compounds known to cause seizures in vivo and/or in the clinic were assessed. RESULTS Seven out of eight compounds evoked a concentration-dependent increase in population spike (PS) area that was statistically significant at higher concentrations (P<0.05; ANOVA). At the highest test concentration the percentage effects (mean+/-s.e.m.), relative to vehicle, were: picrotoxin 212.9+/-28.8, pentylenetrazole (PTZ) 181.4+/-24.7, 4-AP 328.9+/-48.6, aminophylline 124.5+/-5.9, chlorpromazine 122.1+/-9.8, SNC-80 132.1+/-12.6 and penicillin 174.7+/-14.1. Physostigmine had no significant effect on PS area although a concentration-dependent change in the morphology of the response was evident. DISCUSSION All validation compounds evoked a statistically significant effect on synaptic activity in the rat hippocampal slice. Although similar effects have been described previously, this is the first time that the effects of a pharmacologically diverse set of compounds have been assessed using a standardised brain slice assay. Given the low compound usage and relatively high throughput associated with this assay, the hippocampal brain slice assay may facilitate earlier testing of convulsant liability than is currently possible using in vivo models.
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Affiliation(s)
- A Easter
- Safety Assessment UK, AstraZeneca R&D Alderley Park, Macclesfield, SK10 4TG, UK.
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Yu FH, Mantegazza M, Westenbroek RE, Robbins CA, Kalume F, Burton KA, Spain WJ, McKnight GS, Scheuer T, Catterall WA. Reduced sodium current in GABAergic interneurons in a mouse model of severe myoclonic epilepsy in infancy. Nat Neurosci 2006; 9:1142-9. [PMID: 16921370 DOI: 10.1038/nn1754] [Citation(s) in RCA: 761] [Impact Index Per Article: 42.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2006] [Accepted: 08/31/2006] [Indexed: 11/09/2022]
Abstract
Voltage-gated sodium channels (Na(V)) are critical for initiation of action potentials. Heterozygous loss-of-function mutations in Na(V)1.1 channels cause severe myoclonic epilepsy in infancy (SMEI). Homozygous null Scn1a-/- mice developed ataxia and died on postnatal day (P) 15 but could be sustained to P17.5 with manual feeding. Heterozygous Scn1a+/- mice had spontaneous seizures and sporadic deaths beginning after P21, with a notable dependence on genetic background. Loss of Na(V)1.1 did not change voltage-dependent activation or inactivation of sodium channels in hippocampal neurons. The sodium current density was, however, substantially reduced in inhibitory interneurons of Scn1a+/- and Scn1a-/- mice but not in their excitatory pyramidal neurons. An immunocytochemical survey also showed a specific upregulation of Na(V)1.3 channels in a subset of hippocampal interneurons. Our results indicate that reduced sodium currents in GABAergic inhibitory interneurons in Scn1a+/- heterozygotes may cause the hyperexcitability that leads to epilepsy in patients with SMEI.
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Affiliation(s)
- Frank H Yu
- Department of Pharmacology, University of Washington, Seattle, Washington 98195-7280, USA
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Raineteau O, Hugel S, Ozen I, Rietschin L, Sigrist M, Arber S, Gähwiler BH. Conditional labeling of newborn granule cells to visualize their integration into established circuits in hippocampal slice cultures. Mol Cell Neurosci 2006; 32:344-55. [PMID: 16828306 DOI: 10.1016/j.mcn.2006.05.006] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2006] [Revised: 05/09/2006] [Accepted: 05/19/2006] [Indexed: 10/24/2022] Open
Abstract
The dentate gyrus continues to produce new granule cells throughout life. Understanding the mechanisms underlying their integration into the pre-existing hippocampal circuitry is of crucial importance. In the present study, we developed an approach allowing visual tracking of newborn granule cells in hippocampal organotypic slices. By crossing neurogenin 2 (Ngn2-CreER) with Cre-reporter mice expressing YFP or GFP reporter genes, it was possible to observe living cells after treating slice cultures with 4-hydroxytamoxifen to induce Cre recombinase activation. Colocalization of GFP with the mitotic marker BrdU demonstrated that the GFP-expressing granule cells were born in vitro. They mature and integrate normally into the hippocampal circuitry, as shown using morphological and electrophysiological techniques. This ex vivo approach therefore offers a highly accessible model to study the effects of long-term treatments on maturation and integration of newborn granule cells.
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Affiliation(s)
- Olivier Raineteau
- Brain Research Institute, University of Zurich, Zurich, Switzerland.
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Mesquita F, Aguiar JF, Oliveira JA, Garcia-Cairasco N, Varanda WA. Electrophysiological properties of cultured hippocampal neurons from Wistar Audiogenic Rats. Brain Res Bull 2005; 65:177-83. [PMID: 15763185 DOI: 10.1016/j.brainresbull.2005.01.003] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2003] [Accepted: 01/11/2005] [Indexed: 11/17/2022]
Abstract
The main goal of this work was to analyze the electrophysiological properties of cultured hippocampal neurons from a particular epileptic rat strain, called Wistar Audiogenic Rats (WAR). The whole-cell patch-clamp technique was used to record both active and passive membrane responses in an attempt to detect alterations in their characteristics in relation to controls from Wistar rats. Neurons from WARs show a significant reduction in the magnitude of the inhibitory GABAergic currents ( approximately 45%), in spite of maintaining a normal level of the excitatory glutamatergic currents. In addition, the magnitude of potassium currents, measured at +80 mV, is reduced by about 30% in comparison to controls. Surprisingly, we also found important changes in the passive cellular properties in WAR neurons such as membrane potential (-50.0 mV in WARs and -63.1 mV in controls) and input resistance (647 MOmega in WARs and 408 MOmega in controls). The changes described here, could be the basis of the neurophysiological and behavioral alterations present in these hyperexcitable animals, contributing to a better understanding of epileptogenesis in this particular animal model.
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Affiliation(s)
- Fernando Mesquita
- Departamento de Ciências Básicas da Saúde, Faculdade de Ciências Médicas, UFMT, Av. Fernando Correa da Costa, s/n 78060-900 Cuiabá, MT, Brazil.
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