Analysis of ERK1/2 kinases in the inferior colliculus of rats genetically prone to audiogenic seizures during postnatal development.

The activity of ERK1/2 kinases in the quadrigemina inferior colliculus of Krushinsky-Molodkina rats of different age, which are characterized by an increased seizure readiness compared to Wistar rats, was analyzed. An increased (probably genetically determined) activity of these enzymes during the development of epileptiform activity in ontogeny was found, which may be the cause of abnormalities in the neurotransmitter system functioning.

Inhibition of ERK1/2 signaling prevents epileptiform behavior in rats prone to audiogenic seizures.

It has recently been proposed that extracellular signal-regulated kinases 1 and 2 (ERK1/2) are one of the factors mediating seizure development. We hypothesized that inhibition of ERK1/2 activity could prevent audiogenic seizures by altering GABA and glutamate release mechanisms. Krushinsky-Molodkina rats, genetically prone to audiogenic seizure, were recruited in the experiments. Animals were i.p. injected with an inhibitor of ERK1/2 SL 327 at different doses 60 min before audio stimulation. We demonstrated for the first time that inhibition of ERK1/2 activity by SL 327 injections prevented seizure behavior and this effect was dose-dependent and correlated with ERK1/2 activity. The obtained data also demonstrated unchanged levels of GABA production, and an increase in the level of vesicular glutamate transporter 2. The study of exocytosis protein expression showed that SL 327 treatment leads to downregulation of vesicle-associated membrane protein 2 and synapsin I, and accumulation of synaptosomal-associated protein 25 (SNAP-25). The obtained data indicate that the inhibition of ERK1/2 blocks seizure behavior presumably by altering the exocytosis machinery, and identifies ERK1/2 as a potential target for the development of new strategies for seizure treatment. Extracellular signal-regulated kinases 1 and 2 (ERK1/2) are one of the factors mediating seizure development. Here we report that inhibition of ERK1/2 by SL 327 prevented seizure behavior and this effect was dose-dependent and correlated with ERK1/2 activity. Accumulation of VGLUT2 was associated with differential changing of synaptic proteins VAMP2, SNAP-25 and synapsin I. The obtained data indicate that the inhibition of ERK1/2 alters neurotransmitter release by changing the exocytosis machinery, thus preventing seizures.

Opposite caudal versus rostral brain nitric oxide synthase response to generalized seizures in a novel rodent model of reflex epilepsy.

AIMS: Nitric oxide (NO) is synthesized from L-arginine (L-Arg) by three different isoforms of NO synthase (NOS), i.e. the constitutive neuronal and endothelial NOS (nNOS and eNOS) and the inducible NOS (iNOS). NO has been involved in the pathophysiology of epilepsy, but available data are conflicting and the actual role of NO in epilepsy still remains to be clarified. In this study we investigated the basal and post-seizure levels of constitutive NOS (cNOS) activity as well as the expression of the cNOS isoforms across brain regions in a novel model of epilepsy. MAIN METHODS: cNOS activity was assessed in various brain areas along the rostro-caudal axis in control wild type hamsters, unstimulated generalized audiogenic seizure prone hamsters, Salamanca strain, GASH:Sal and GASH:Sal after 10 sound-induced epileptic seizures. Additionally, Western blot experiments for nNOS and eNOS were performed in those areas where relevant changes in cNOS activity were found. KEY FINDINGS: In the GASH:Sal, cNOS activity increased in the mesencephalic areas studied while cNOS activity decreased in both the striatum and cerebral cortex after 10 sound-induced epileptic seizures. nNOS (but not eNOS) expression paralleled the variations in cNOS activity. The same sound stimulation had no effect on control hamsters. SIGNIFICANCE: These results suggest a different NOS response in the regions close to the original epileptic focus (caudal, in our auditory model) versus the remote areas (rostral) possibly recruited at later stages or after repeated crises. These findings may account for some of the discrepancies found regarding the role of NO in epilepsy.

cAMP-dependent phosphorylation of microtubule-associated protein-2 during treatment of sodium valproate and audiogenic kindling.

Administration of anticonvulsant sodium valproate alleviated audiogenic seizures in Krushinskii-Molodkina rats, which was accompanied by a decrease in cAMP-dependent phosphorylation of microtubule-associated protein MAP2 in the hippocampus ex vivo. In contrast, audiogenic kindling resulted in a marked increase in MAP2 phosphorylation at cAMP-dependent protein kinase-specific sites. These changes in the state of MAP2 phosphorylation providing restructuring of dendrites in response to specific influences modulate neuronal activity and are the important mechanisms of neuronal plasticity.

Candidate gene analysis of the succinic semialdehyde dehydrogenase gene (ALDH5A1) in patients with idiopathic generalized epilepsy and photosensitivity.

Succinic semialdehyde dehydrogenase (SSADH) is involved in the degradation of the inhibitory neurotransmitter GABA and about 50% of patients with SSADH deficiency suffer from seizures. The gene encoding SSADH (gene symbol: ALDH5A1) maps in proximity to susceptibility loci for juvenile myoclonic epilepsy (JME) and photosensitivity on chromosome 6p22. The present study tested whether variation of the ALDH5A1 gene confers susceptibility to common syndromes of idiopathic generalized epilepsy (IGE) and an abnormal photoparoxysmal response (PPR). Mutation screening of the ALDH5A1 coding sequence of 35IGE/PPR patients and four healthy control subjects identified 17 sequence variants, of which three resulted in an exchange of amino acids (H180Y, P182L, A237S). Association analysis was carried out for six single nucleotide polymorphisms (SNPs) and one trinucleotide repeat polymorphism (TNR, intron 1), covering the genomic ALDH5A1 sequence. The study sample comprised 566 unrelated German IGE patients, including 218 JME and 95 photosensitive IGE patients, 78 PPR probands without IGE, and 662 German population controls. None of the investigated ALDH5H1 polymorphisms showed evidence for an allelic or genotypic association with either IGE, JME, or PPR, when corrected for multiple tests. A tentative haplotypic association of the two-marker haplotype (rs1883415-TNR) covering the 5'-regulatory region in IGE patients (chi2=11.65, d.f.=3, P=0.009) warrants further replication studies. The present results do not provide evidence that any ALDH5A1 missense variant itself contributes a common and substantial susceptibility effect (RR>2) to IGE syndromes or an increased liability to visually-induced cortical synchronization.

[Induction of NO-synthase and glial fibrillary acidic protein in astrocytes of the temporal cortex in rats with audiogenic epileptiform reaction]. / Induktsiia NO-sintazy i glial'nogo kislogo fibrilliarnogo belka v astrotsitakh visochnoi kory krys s audiogennoi épileptiformnoi reaktsiei.

The localization of NADPH-diaphorase (NADPH-d), inducible NO-synthase (iNOS) and glial fibrillary acidic protein (GFAP) was studied in the astrocytes of the temporal cortex in rats of Krushinsky-Molodkina strain which are genetically prone to audiogenic seizures. The seizure was evoked by thrice-repeated acoustic stimulation. Wistar rats and acoustically untreated seizure-free Krushinsky-Molodkina rats were used as a control. The foci of brain damage were consistently found in the neocortex of the animals with audiogenic seizures. Epileptic foci, 300-400 microm in diameter, were localized in layers III-V; they were found to consist of the clusters of NADPH-d-positive astrocytes and to be present in both hemispheres. In the foci of cortical damage astrocytes expressed iNOS and an elevated level of GFAP. The number of GFAP-immunopositive astrocytes in the foci of damage was increased by 25-37% compared to the control and to undamaged areas of the cortex. Astrocyte NOS and GFAP induction found in this work, suggests the participation of glia in compensatory NO-dependent mechanisms, that are formed in the damage foci of neocortex during the audiogenic seizures.

Early visual seizures and progressive myoclonus epilepsy in neuronopathic Gaucher disease due to a rare compound heterozygosity (N188S/S107L).

PURPOSE: Gaucher disease, the inherited deficiency of the lysosomal enzyme glucocerebrosidase, is characterized by genotypic and phenotypic heterogeneity. We recently characterized the glucocerebrosidase alleles of a patient with an unusual clinical presentation of type 3 Gaucher disease. METHODS: Initial clinical manifestations appeared at age 11 years as visual seizures. RESULTS: Subsequent progressive myoclonus and generalized seizures were consistent with an adolescent-onset form of progressive myoclonus epilepsy. However, a specific diagnosis was established only at age 16, because of the absence of hematologic abnormalities and a fairly moderate hepatomegaly. Bone marrow aspirate was slightly positive for Gaucher cells. Demonstration of reduced glucocerebrosidase in the fibroblasts confirmed the diagnosis. The child died at age 19 years. Postmortem sequencing of the glucocerebrosidase gene from cultured fibroblasts demonstrated a rare compound heterozygote for N188S/S107L. CONCLUSIONS: This unusual presentation of Gaucher disease indicates that if clinical and neurophysiological findings in adolescents with initial visual seizures and myoclonus suggest a progressive disorder, enzymatic assay is mandatory, even in the absence of the classic neurologic and systemic signs of the disease. Early differential diagnosis from other forms of progressive myoclonus epilepsy with similar clinical presentation may help provide appropriate genetic counseling.

Fold prediction and comparative modeling of Bdm1: a probable alpha/beta hydrolase associated with hot water epilepsy.

Hot water epilepsy (HWE) is a benign and rare form of reflex epilepsy that occurs most commonly in humans. Bdm1 is one of the proteins whose mRNA transcript is overexpressed during HWE in a rat model. We show, by sequence analysis and fold recognition methods, that Bdm1 has strong structural similarities to alpha/beta hydrolases like the thioesterases. A three-dimensional model derived by comparative modeling methods allowed the search for catalytic residues using a flexible functional template characteristic of these enzymes. We predict that Bdm1 might be regulated by homocysteine levels by means of direct participation in degradation pathways.

Transplantation of M213-2O cells with enhanced GAD67 expression into the inferior colliculus alters audiogenic seizures.

The purpose of the present study was to examine the effects of GABA-producing cell transplants on audiogenic seizures (AGS). The M213-2O cell line was derived from fetal rat striatum and has GABAergic properties. This cell line was further modified to express human GAD(67) and produce elevated levels of GABA. The present study compares the effects of parent M213-2O cell transplants with those of GAD(67)-modified M213-2O cells in AGS-prone Long-Evans rats. Two weeks following implantation of engineered cells, latency to AGS-typical wild running was increased compared to nonimplanted subjects. Survival of the transplanted cells was confirmed by immunochemical labeling of GAD(67) and Epstein-Barr virus nuclear antigen. These findings support the use of GABA-producing cell lines to modify seizure activity.