151
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Schartz ND, Herr SA, Madsen L, Butts SJ, Torres C, Mendez LB, Brewster AL. Spatiotemporal profile of Map2 and microglial changes in the hippocampal CA1 region following pilocarpine-induced status epilepticus. Sci Rep 2016; 6:24988. [PMID: 27143585 PMCID: PMC4855223 DOI: 10.1038/srep24988] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2015] [Accepted: 04/06/2016] [Indexed: 01/01/2023] Open
Abstract
Status epilepticus (SE) triggers pathological changes to hippocampal dendrites that may promote epileptogenesis. The microtubule associated protein 2 (Map2) helps stabilize microtubules of the dendritic cytoskeleton. Recently, we reported a substantial decline in Map2 that coincided with robust microglia accumulation in the CA1 hippocampal region after an episode of SE. A spatial correlation between Map2 loss and reactive microglia was also reported in human cortex from refractory epilepsy. New evidence supports that microglia modulate dendritic structures. Thus, to identify a potential association between SE-induced Map2 and microglial changes, a spatiotemporal profile of these events is necessary. We used immunohistochemistry to determine the distribution of Map2 and the microglia marker IBA1 in the hippocampus after pilocarpine-induced SE from 4 hrs to 35 days. We found a decline in Map2 immunoreactivity in the CA1 area that reached minimal levels at 14 days post-SE and partially increased thereafter. In contrast, maximal microglia accumulation occurred in the CA1 area at 14 days post-SE. Our data indicate that SE-induced Map2 and microglial changes parallel each other’s spatiotemporal profiles. These findings may lay the foundation for future mechanistic studies to help identify potential roles for microglia in the dendritic pathology associated with SE and epilepsy.
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Affiliation(s)
- Nicole D Schartz
- Department of Psychological Sciences, West Lafayette, IN 47907, USA
| | - Seth A Herr
- Department of Psychological Sciences, West Lafayette, IN 47907, USA
| | - Lauren Madsen
- Department of Psychological Sciences, West Lafayette, IN 47907, USA
| | - Sarah J Butts
- Department of Psychological Sciences, West Lafayette, IN 47907, USA
| | - Ceidy Torres
- School of Science and Technology, Universidad del Este, Carolina, PR 00984, Puerto Rico
| | - Loyda B Mendez
- School of Science and Technology, Universidad del Este, Carolina, PR 00984, Puerto Rico
| | - Amy L Brewster
- Department of Psychological Sciences, West Lafayette, IN 47907, USA.,Weldon School of Biomedical Engineering, West Lafayette, IN 47907, USA
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152
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Töllner K, Twele F, Löscher W. Evaluation of the pentylenetetrazole seizure threshold test in epileptic mice as surrogate model for drug testing against pharmacoresistant seizures. Epilepsy Behav 2016; 57:95-104. [PMID: 26930359 DOI: 10.1016/j.yebeh.2016.01.032] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/19/2015] [Revised: 01/27/2016] [Accepted: 01/30/2016] [Indexed: 11/17/2022]
Abstract
Resistance to antiepileptic drugs (AEDs) is a major problem in epilepsy therapy, so that development of more effective AEDs is an unmet clinical need. Several rat and mouse models of epilepsy with spontaneous difficult-to-treat seizures exist, but because testing of antiseizure drug efficacy is extremely laborious in such models, they are only rarely used in the development of novel AEDs. Recently, the use of acute seizure tests in epileptic rats or mice has been proposed as a novel strategy for evaluating novel AEDs for increased antiseizure efficacy. In the present study, we compared the effects of five AEDs (valproate, phenobarbital, diazepam, lamotrigine, levetiracetam) on the pentylenetetrazole (PTZ) seizure threshold in mice that were made epileptic by pilocarpine. Experiments were started 6 weeks after a pilocarpine-induced status epilepticus. At this time, control seizure threshold was significantly lower in epileptic than in nonepileptic animals. Unexpectedly, only one AED (valproate) was less effective to increase seizure threshold in epileptic vs. nonepileptic mice, and this difference was restricted to doses of 200 and 300 mg/kg, whereas the difference disappeared at 400mg/kg. All other AEDs exerted similar seizure threshold increases in epileptic and nonepileptic mice. Thus, induction of acute seizures with PTZ in mice pretreated with pilocarpine does not provide an effective and valuable surrogate method to screen drugs for antiseizure efficacy in a model of difficult-to-treat chronic epilepsy as previously suggested from experiments with this approach in rats.
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Affiliation(s)
- Kathrin Töllner
- Department of Pharmacology, Toxicology, and Pharmacy, University of Veterinary Medicine, Hannover, Germany; Center for Systems Neuroscience, Hannover, Germany
| | - Friederike Twele
- Department of Pharmacology, Toxicology, and Pharmacy, University of Veterinary Medicine, Hannover, Germany; Center for Systems Neuroscience, Hannover, Germany
| | - Wolfgang Löscher
- Department of Pharmacology, Toxicology, and Pharmacy, University of Veterinary Medicine, Hannover, Germany; Center for Systems Neuroscience, Hannover, Germany.
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153
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Salami P, Lévesque M, Avoli M. High frequency oscillations can pinpoint seizures progressing to status epilepticus. Exp Neurol 2016; 280:24-9. [PMID: 27018321 DOI: 10.1016/j.expneurol.2016.03.021] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2015] [Revised: 02/10/2016] [Accepted: 03/20/2016] [Indexed: 11/27/2022]
Abstract
Status epilepticus (SE) is defined as a seizure lasting more than 5min or a period of recurrent seizures without recovery between them. SE is a serious emergency condition that requires immediate intervention; therefore, identifying SE electrophysiological markers may translate in prompt care to stop it. Here, we analyzed the EEG signals recorded from the CA3 region of the hippocampus and the entorhinal cortex in rats that responded to systemic administration of 4-aminopyridine (4AP) by generating either isolated seizures or seizures progressing to SE. We found that high frequency oscillations (HFOs) - which can be categorized as ripples (80-200Hz) and fast ripples (250-500Hz) - had different patterns of occurrence in the two groups (n=5 for each group). Specifically, fast ripples in CA3 and entorhinal cortex of the SE group occurred at higher rates than ripples, both during the ictal and post-ictal periods when compared to the HFOs recorded from the isolated seizure group. Our data reveal that different patterns of HFO occurrence can pinpoint seizures progressing to SE, thus suggesting the involvement of different neuronal networks at the termination of seizure discharges.
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Affiliation(s)
- Pariya Salami
- Montreal Neurological Institute, McGill University, Montréal H3A 2B4 QC, Canada; Department of Neurology & Neurosurgery, McGill University, Montréal H3A 2B4 QC, Canada; Department of Physiology, McGill University, Montréal H3A 2B4 QC, Canada
| | - Maxime Lévesque
- Montreal Neurological Institute, McGill University, Montréal H3A 2B4 QC, Canada; Department of Neurology & Neurosurgery, McGill University, Montréal H3A 2B4 QC, Canada; Department of Physiology, McGill University, Montréal H3A 2B4 QC, Canada
| | - Massimo Avoli
- Montreal Neurological Institute, McGill University, Montréal H3A 2B4 QC, Canada; Department of Neurology & Neurosurgery, McGill University, Montréal H3A 2B4 QC, Canada; Department of Physiology, McGill University, Montréal H3A 2B4 QC, Canada.
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154
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Berdyyeva TK, Frady EP, Nassi JJ, Aluisio L, Cherkas Y, Otte S, Wyatt RM, Dugovic C, Ghosh KK, Schnitzer MJ, Lovenberg T, Bonaventure P. Direct Imaging of Hippocampal Epileptiform Calcium Motifs Following Kainic Acid Administration in Freely Behaving Mice. Front Neurosci 2016; 10:53. [PMID: 26973444 PMCID: PMC4770289 DOI: 10.3389/fnins.2016.00053] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2015] [Accepted: 02/05/2016] [Indexed: 12/24/2022] Open
Abstract
Prolonged exposure to abnormally high calcium concentrations is thought to be a core mechanism underlying hippocampal damage in epileptic patients; however, no prior study has characterized calcium activity during seizures in the live, intact hippocampus. We have directly investigated this possibility by combining whole-brain electroencephalographic (EEG) measurements with microendoscopic calcium imaging of pyramidal cells in the CA1 hippocampal region of freely behaving mice treated with the pro-convulsant kainic acid (KA). We observed that KA administration led to systematic patterns of epileptiform calcium activity: a series of large-scale, intensifying flashes of increased calcium fluorescence concurrent with a cluster of low-amplitude EEG waveforms. This was accompanied by a steady increase in cellular calcium levels (>5 fold increase relative to the baseline), followed by an intense spreading calcium wave characterized by a 218% increase in global mean intensity of calcium fluorescence (n = 8, range [114–349%], p < 10−4; t-test). The wave had no consistent EEG phenotype and occurred before the onset of motor convulsions. Similar changes in calcium activity were also observed in animals treated with 2 different proconvulsant agents, N-methyl-D-aspartate (NMDA) and pentylenetetrazol (PTZ), suggesting the measured changes in calcium dynamics are a signature of seizure activity rather than a KA-specific pathology. Additionally, despite reducing the behavioral severity of KA-induced seizures, the anticonvulsant drug valproate (VA, 300 mg/kg) did not modify the observed abnormalities in calcium dynamics. These results confirm the presence of pathological calcium activity preceding convulsive motor seizures and support calcium as a candidate signaling molecule in a pathway connecting seizures to subsequent cellular damage. Integrating in vivo calcium imaging with traditional assessment of seizures could potentially increase translatability of pharmacological intervention, leading to novel drug screening paradigms and therapeutics designed to target and abolish abnormal patterns of both electrical and calcium excitation.
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Affiliation(s)
| | - E Paxon Frady
- InscopixPalo Alto, CA, USA; Redwood Center for Theoretical Neuroscience, University of California, BerkeleyBerkeley, CA, USA
| | | | - Leah Aluisio
- Janssen Research & Development, LLC San Diego, CA, USA
| | | | | | - Ryan M Wyatt
- Janssen Research & Development, LLC San Diego, CA, USA
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155
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Imran I, Hillert MH, Klein J. Early metabolic responses to lithium/pilocarpine-induced status epilepticus in rat brain. J Neurochem 2015; 135:1007-18. [DOI: 10.1111/jnc.13360] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2015] [Revised: 08/25/2015] [Accepted: 08/29/2015] [Indexed: 01/04/2023]
Affiliation(s)
- Imran Imran
- Department of Pharmacology; School of Pharmacy; Biocenter N260; Goethe University Frankfurt; Frankfurt am Main Germany
- Faculty of Pharmacy; Bahauddin Zakariya University; Multan Pakistan
| | - Markus H. Hillert
- Department of Pharmacology; School of Pharmacy; Biocenter N260; Goethe University Frankfurt; Frankfurt am Main Germany
| | - Jochen Klein
- Department of Pharmacology; School of Pharmacy; Biocenter N260; Goethe University Frankfurt; Frankfurt am Main Germany
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