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The matrix metalloproteinase inhibitor marimastat inhibits seizures in a model of kainic acid-induced status epilepticus.

ABSTRACT: An intra-hippocampus injection of kainic acid serves as a model of status epilepticus and the subsequent development of temporal lobe epilepsy. Matrix metalloproteinase-9 (MMP-9) is an enzyme that controls remodeling of the extracellular milieu under physiological and pathological conditions. In response to brain insult, MMP-9 contributes to pathological synaptic plasticity that may play a role in the progression of an epileptic condition. Marimastat is a metalloproteinase inhibitor that was tested in clinical trials of cancer. The present study assessed whether marimastat can impair the development of epilepsy. The inhibitory efficacy of marimastat was initially tested in neuronal cultures in vitro. As a marker substrate, we used nectin-3. Next, we investigated the blood-brain barrier penetration of marimastat using mass spectrometry and evaluated the therapeutic potential of marimastat against seizure outcomes. We found that marimastat inhibited the cleavage of nectin-3 in hippocampal neuronal cell cultures. Marimastat penetrated the blood-brain barrier and exerted an inhibitory effect on metalloproteinase activity in the brain. Finally, marimastat decreased some seizure parameters, such as seizure score and number, but did not directly affect status epilepticus. The long-term effects of marimastat were evident up to 6 weeks after kainic acid administration, in which marimastat still inhibited seizure duration.

SUBMITTER: Pijet B

PROVIDER: S-EPMC7718901 | biostudies-literature | 2020 Dec

REPOSITORIES: biostudies-literature

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The matrix metalloproteinase inhibitor marimastat inhibits seizures in a model of kainic acid-induced status epilepticus.

Pijet Barbara B Konopka Anna A Rejmak Emilia E Stefaniuk Marzena M Khomiak Danylo D Bulska Ewa E Pikul Stanisław S Kaczmarek Leszek L

Scientific reports 20201204 1

An intra-hippocampus injection of kainic acid serves as a model of status epilepticus and the subsequent development of temporal lobe epilepsy. Matrix metalloproteinase-9 (MMP-9) is an enzyme that controls remodeling of the extracellular milieu under physiological and pathological conditions. In response to brain insult, MMP-9 contributes to pathological synaptic plasticity that may play a role in the progression of an epileptic condition. Marimastat is a metalloproteinase inhibitor that was tes ...[more]

PMID: 33277582

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Project description:Injection of the seaweed toxin kainic acid (KA) in rats induces a severe status epilepticus initiating complex neuropathological changes in limbic brain areas and subsequently spontaneous recurrent seizures. Although neuropathological changes have been intensively investigated in the hippocampus proper and the dentate gyrus in various seizure models, much less is known about changes in parahippocampal areas. We now established telemetric EEG recordings combined with continuous video monitoring to characterize the development of spontaneous seizures after KA-induced status epilepticus, and investigated associated neurodegenerative changes, astrocyte and microglia proliferation in the subiculum and other parahippocampal brain areas. The onset of spontaneous seizures was heterogeneous, with an average latency of 15 ± 1.4 days (range 3-36 days) to the initial status epilepticus. The frequency of late spontaneous seizures was higher in rats in which the initial status epilepticus was recurrent after its interruption with diazepam compared to rats in which this treatment was more efficient. Seizure-induced neuropathological changes were assessed in the subiculum by losses in NeuN-positive neurons and by Fluoro-Jade C staining of degenerating neurons. Neuronal loss was already prominent 24 h after KA injection and only modestly progressed at the later intervals. It was most severe in the proximal subiculum and in layer III of the medial entorhinal cortex and distinct Fluoro-Jade C labeling was observed there in 75% of rats even after 3 months. Glutamatergic neurons, labeled by in situ hybridization for the vesicular glutamate transporter 1 followed a similar pattern of cell losses, except for the medial entorhinal cortex and the proximal subiculum that appeared more vulnerable. Glutamate decarboxylase65 (GAD65) mRNA expressing neurons were generally less vulnerable than glutamate neurons. Reactive astrocytes and microglia were present after 24 h, however, became prominent only after 8 days and remained high after 30 days. In the proximal subiculum, parasubiculum and entorhinal cortex the number of microglia cells was highest after 30 days. Although numbers of reactive astrocytes and microglia were reduced again after 3 months, they were still present in most rats. The time course of astrocyte and microglia proliferation parallels that of epileptogenesis.

Project description:PurposeThe immature rat brain is highly susceptible to seizures, but has a resistance to pathological changes induced by seizures as compared to adult rats. However, prolonged seizures during early-life enhance cellular injury and hyperexcitability induced by convulsive insults later in adulthood. The mechanisms underlying these phenomena are not understood. In adult models, the CA1 axons reorganize their projections to subiculum. Seizure induced plasticity in this pathway has not been investigated in immature seizure models, and may contribute to the vulnerability to later seizures.MethodsOn postnatal day 15, rats experienced convulsive status epilepticus with kainic acid (KA). Seizure induced plasticity was examined with Timm histochemistry and iontophoretic injections of sodium selenite, a retrograde tracer. Cellular injury was evaluated with Fluoro-Jade B histochemistry.ResultsRetrograde tracing experiments determined a 67% larger dorsoventral extent of retrograde labeling in the CA1 pyramidal region after tracer injections in subiculum. The synaptic reorganization of the CA1 projection to subiculum was noted in the absence of overt neuronal injury in subiculum or CA1. In contrast, mossy fiber sprouting was detected into the stratum oriens of CA3 with limited neuronal injury to CA3 pyramidal neurons. No mossy fiber sprouting into the inner molecular layer of the dentate gyrus, or CA1 sprouting into the stratum moleculare of CA1 were noted.ConclusionsThe results indicate that the developing brain has distinct mechanisms of seizure induced reorganization as compared to the adult brain. Our experiments show that the concept of "resistance of the immature brain to excitotoxicity" is considerably more complicated than generally believed. Morphological plasticity in the immature brain appears more extensive in distal, but not proximal, projections of hippocampal pathways, and across hippocampal lamellae. The abnormal connectivity between hippocampal lamellae might play a role in the increased susceptibility to injury and hyperexcitability associated with later convulsive insults.

Project description:The aim of epilepsy models is to investigate disease ontogenesis and therapeutic interventions in a consistent and prospective manner. The kainic acid-induced status epilepticus (KASE) rat model is a widely used, well-validated model for temporal lobe epilepsy (TLE). As we noted significant variability within the model between labs potentially related to the rat strain used, we aimed to describe two variants of this model with diverging seizure phenotype and neuropathology. In addition, we evaluated two different protocols to induce status epilepticus (SE). Wistar Han (Charles River, France) and Sprague-Dawley (Harlan, The Netherlands) rats were subjected to KASE using the Hellier kainic acid (KA) and a modified injection scheme. Duration of SE and latent phase were characterized by video-electroencephalography (vEEG) in a subgroup of animals, while animals were sacrificed 1?week (subacute phase) and 12?weeks (chronic phase) post-SE. In the 12?weeks post-SE groups, seizures were monitored with vEEG. Neuronal loss (neuronal nuclei), microglial activation (OX-42 and translocator protein), and neurodegeneration (Fluorojade C) were assessed. First, the Hellier protocol caused very high mortality in WH/CR rats compared to SD/H animals. The modified protocol resulted in a similar SE severity for WH/CR and SD/H rats, but effectively improved survival rates. The latent phase was significantly shorter (p?<?0.0001) in SD/H (median 8.3?days) animals compared to WH/CR (median 15.4?days). During the chronic phase, SD/H rats had more seizures/day compared to WH/CR animals (p?<?0.01). However, neuronal degeneration and cell loss were overall more extensive in WH/CR than in SD/H rats; microglia activation was similar between the two strains 1?week post-SE, but higher in WH/CR rats 12?weeks post-SE. These neuropathological differences may be more related to the distinct neurotoxic effects of KA in the two rat strains than being the outcome of seizure burden itself. The divergences in disease progression and seizure outcome, in addition to the histopathological dissimilarities, further substantiate the existence of strain differences for the KASE rat model of TLE.

Dataset Information

The matrix metalloproteinase inhibitor marimastat inhibits seizures in a model of kainic acid-induced status epilepticus.

Publications

The matrix metalloproteinase inhibitor marimastat inhibits seizures in a model of kainic acid-induced status epilepticus.

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