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PubMed2003

Depressive-like behavioral alterations and c-fos expression in the dopaminergic brain regions in WAG/Rij rats with genetic absence epilepsy.

Wistar derived inbred line, the WAG/Rij rats, genetically absence epilepsy prone and their normal counterparts, outbred Wistar rats, were compared in respect to differences in behavior, in acute and chronic antidepressant imipramine treatment and in the immediate early gene c-fos expression in the brain regions induced by forced swimming test procedure. The WAG/Rij rats as compared with Wistar rats were found to exhibit decreased activity in the open field test, increased immobility in the forced swimming test and decreased sucrose intake (anhedonia). Interline differences indicating increased anxiety in the WAG/Rij rats were not revealed in the light-dark choice, social interaction and elevated plus-maze tests. The WAG/Rij rats in contrast to Wistar rats responded only to chronic antidepressant imipramine treatment with a reduction in their enhanced immobility in the forced swimming test. "Behavioral despair" induced by forced swimming led to c-fos expression in frontal cortex, nucleus accumbens and striatum, terminal regions of three dopaminergic brain systems (mesocortical, mesolimbic, nigrostriatal). The c-fos expression in the brain of WAG/Rij rats was substantially higher than that of Wistar rats. Moreover, the strains differed in the distribution of c-fos expression between brain regions. Results suggest that WAG/Rij rats are prone to adopt passive strategies of behavior in stressful situations, and so in this certain aspect this strain might be regarded as new experimental (genetic) model of depressive-like (passive) behavior accompanying absence epilepsy. Further testing this hypothesis is proceeding. This putative model could be used for the investigation of neurobiological basis and mechanisms of such "double pathology" and for the examination of new concepts of its therapy.

Animals↗
PubMed2005

The effects of the immature rat model of febrile seizures on the occurrence of later generalized tonic-clonic and absence epilepsy.

This study was designed to investigate whether the intensity of experimental febrile seizures reduces the threshold to generalized tonic-clonic epilepsy and its effects on the development of generalized absence epilepsy in adulthood. For the evaluation of absence epilepsy, WAG/Rij rats and for the tonic-clonic seizures, PTZ injected Wistar rats were used. Our results showed that while the frequency of the experimental febrile seizures facilitates PTZ-induced generalized tonic-clonic seizures, it does not influence the properties of absence epileptic seizures in adulthood.

Action Potentials↗
PubMed2001

Up-regulation of D3 dopaminergic receptor mRNA in the core of the nucleus accumbens accompanies the development of seizures in a genetic model of absence-epilepsy in the rat.

The basal ganglia system is thought to play a key role in the control of absence-seizures and there is ample evidence that epileptic seizures modify brain dopamine function. We recently reported that local injections of dopamine D1 or D2 agonists in the core of the nucleus accumbens suppressed absence-seizures in a spontaneous, genetic rodent model of absence-epilepsy whereas injections of D1 or D2 antagonists had aggravating effects. These findings raised the possibility that the dopaminergic system may be altered in absence-epilepsy prone rats. Therefore, we studied by in situ hybridization histochemistry the expression of pre- and postsynaptic components of the dopaminergic system in this strain of rats. When compared to non-epileptic control rats, epileptic rats displayed no change in the expression of mRNAs coding for the neuronal dopaminergic markers (tyrosine hydroxylase, membraneous and vesicular dopamine transporters). In addition, there was no difference between the two strains concerning the expression of the dopamine receptor transcripts D1, D2 and D5. In adult absence-epilepsy prone rat with an overt epileptic phenotype, however, an elevated level of D3 mRNA expression was observed in neurons of the core of the nucleus accumbens (+23% increase in silver grain density compared to non-epileptic control rats). D3 transcripts were not increased in juvenile epileptic rats without seizures. These findings suggests that up-regulation of D3 receptor mRNA is part of the epileptic phenotype in absence-epilepsy prone rats. Its localization in the core of the nucleus accumbens bears close resemblance to the dopamine-sensitive antiepileptic sites in ventral striatum and further support the involvement of ventral structures of the basal ganglia system in the control of absence-seizures.

Animals↗
PubMed1992

Genetic absence epilepsy in rats from Strasbourg--a review.

We have selected a strain of rats and designated it the Genetic Absence Epilepsy Rat from Strasbourg (GAERS). In this strain, 100% of the animals present recurrent generalized non-convulsive seizures characterized by bilateral and synchronous spike-and-wave discharges accompanied with behavioural arrest, staring and sometimes twitching of the vibrissae. Spontaneous SWD (7-11 cps, 300-1,000 microV, 0.5-75 sec) start and end abruptly on a normal background EEG. They usually occur at a mean frequency of 1.5 per min when the animals are in a state of quiet wakefulness. Drugs effective against absence seizures in humans (ethosuccimide, trimethadione, valproate, benzodiazepines) suppress the SWD dose-dependently, whereas drugs specific for convulsive or focal seizures (carbamazepine, phenytoin) are ineffective. SWD are increased by epileptogenic drugs inducing petit mal-like seizures, such as pentylenetetrazol, gamma-hydroxybutyrate, THIP and penicillin. Depth EEG recordings and lesion experiments show that SWD in GAERs depend on cortical and thalamic structures with a possible rhythmic triggering by the lateral thalamus. Most neurotransmitters are involved in the control of SWD (dopamine, noradrenaline, NMDA, acetylcholine), but GABA and gamma-hydroxybutyrate (GHB) seem to play a critical role. SWD are genetically determined with an autosomal dominant inheritance. The variable expression of SWD in offsprings from GAERS x control reciprocal crosses may be due to the existence of multiple genes. Neurophysiological, behavioural, pharmacological and genetic studies demonstrate that spontaneous SWD in GAERS fulfill all the requirements for an experimental model of absence epilepsy. As the mechanisms underlying absence epilepsy in humans are still unknown, the analysis of the genetic thalamocortical dysfunction in GAERS may be fruitful in investigations of the pathogenesis of generalized non-convulsive seizures.

Action Potentials↗
PubMed1997

Prognostic factors for childhood and juvenile absence epilepsies.

To assess prognostic factors for absence epilepsy (AE), we analyzed data from 80 patients treated for childhood AE (CAE; n = 53) or juvenile AE (JAE; n = 27) in our epilepsy clinic between 1985 and 1992. All patients were classified according to the International Classification of Epileptic Syndromes which was proposed by the International League against Epilepsy in 1989. Patients were separated into two groups based on the course of disease under adequate treatment: Complete response group (CRG): disappearance of absence seizures (AS) or generalized tonic-clonic seizures (GTCS). Poor response group (PRG): persistence of AS and/or GTCS. Approximately 40% of both CAE and JAE patients had poor response. One parameter was associated with poor prognosis in CAE patients, the presence of polyspikes or polyspikes and waves during sleep. No statistical correlation was made for JAE patients. GTCS were frequent in JAE and GTCS occurrence in CAE patients was associated significantly with age at onset after 8 (p < 0.05). The fact that social and educational performance was poorer in the PRG of both types of AE underlines the importance of therapeutic response in patient rehabilitation.

Adolescent↗
PubMed1999

Possible association between childhood absence epilepsy and the gene encoding GABRB3.

BACKGROUND: Childhood Absence Epilepsy (CAE) is considered to have a predominantly, perhaps exclusively, genetic background. To date, genes responsible for susceptibility to CAE have not been identified. The object of the present study was to test association between CAE and the genes encoding the gamma-aminobutyric acid (GABA) type-A receptor subunits alpha 5 (GABRA5) and beta 3 (GABRB3) located on the long arm of chromosome 15 (15q11-q13). METHODS: A family-based candidate gene approach was applied: 50 Austrian nuclear families ascertained for the presence of an affected child were investigated. GABRA5 and GABRB3 subunit genes were genotyped using DNA gained from peripheral blood samples by Polymerase Chain Reactions (PCR). Genetic association was tested using a Monte Carlo Version of the multi-allele Transmission-Disequilibrium Test (TDT). RESULTS: The TDT displayed significant overall association with GABRB3 (p = .0118). CONCLUSIONS: The present data suggest that the tested polymorphism may be either directly involved in the etiology of CAE or in linkage disequilibrium with disease-predisposing sites.

Adolescent↗
PubMedDate not supplied

[Are WAG/Rij rats with genetic absence epilepsy anxious?].

Behavior of susceptible and non-susceptible to audiogenic (convulsive) seizures rats from inbred WAG/Rij strain, genetically predisposed to absence epilepsy, and outbred Wistar strain, genetically not predisposed to absence epilepsy, was compared to assess the level of anxiety (in open field, light-dark choice and elevated plus-maze tests) and the level of depressiveness (in the sucrose consumption and forced swimming tests). Increased level of anxiety was found only in susceptible to audiogenic seizures rats both from WAG/Rij and Wistar strain, but increased level of depressiveness was found only in WAG/Rij strain rats as compared with Wistar rats independently of their susceptibility to audiogenic seizures. Results suggest that increased depressiveness in WAG/Rij strain rats is associated with absence epilepsy but increased anxiety with susceptibility to audiogenic seizures.

Animals↗
PubMed2006

CACNA1I is not associated with childhood absence epilepsy in the Chinese Han population.

This study investigated whether the T-type calcium channel gene CACNA1I causes susceptibility in the Chinese Han population to childhood absence epilepsy, a form of idiopathic generalized seizure disorder. For this investigation, we searched for mutations in the 35 exons and exon-intron boundaries of the CACNA1I gene in 50 Han Chinese patients with childhood absence epilepsy. Seventeen single nucleotide polymorphisms were identified in the 35 exons. Using six single nucleotide polymorphisms as markers, the allele and genotype distributions of all of the identified single nucleotide polymorphisms were examined; there was no significant difference between the childhood absence epilepsy cases and the control groups. Thus, we do not consider the CACNA1I gene to be an important susceptibility gene for childhood absence epilepsy in the Chinese Han population.

Adolescent↗
PubMed1992

Effect of add-on amantadine therapy for refractory absence epilepsy.

Amantadine hydrochloride was administered as an add-on drug to four children with refractory absence epilepsy, resulting in complete resolution of absence episodes within 1 week. All patients remained free of symptoms for 27 to 36 months without adverse effects related to this drug. An attempt to discontinue the use of this medication in three children resulted in a prompt relapse. The suggestion that amantadine may be an effective drug in the treatment of refractory absence epilepsy, should be tested in a double-blind, controlled study.

Amantadine↗
PubMed1995

Selective increase in T-type calcium conductance of reticular thalamic neurons in a rat model of absence epilepsy.

The properties of voltage-dependent calcium currents were compared in thalamic neurons acutely dissociated from a rat model of absence epilepsy, designated as Genetic Absence Epilepsy Rat from Strasbourg (GAERS), and from a Nonepileptic Control strain (NEC). Two populations of neurons were isolated: thalamocortical relay neurons of the nucleus ventrobasalis (VB) and neurons of the nucleus reticularis (RT) of the thalamus. Whole-cell patch-clamp analysis demonstrated an increase in the amplitude of the calcium (Ca2+) current with a low threshold of activation (IT) in RT neurons of GAERS in comparison to that of the seizure-free rat strain (-198 +/- 19 pA and -128 +/- 14 pA, respectively), whereas the sustained component (IL) was not significantly different. The kinetic properties, voltage dependence, and basic pharmacological sensitivity of the Ca2+ conductances were similar in the two populations of neurons. The amplitude of both IT and IL in RT neurons increased after birth, and differences in IT between GAERS and NEC attained significance after postnatal day 11. At corresponding ages, the Ca2+ currents in VB thalamocortical relay neurons were not altered in GAERS in comparison to those in NEC. We conclude that the selective increase in IT of RT neurons enhances the probability of recurrent intrathalamic burst activity, thereby strengthening the synchronizing mechanisms in thalamocortical systems, and, as such, represents a possible primary neuronal dysfunction that relates to the pathological increase in synchronization underlying the generation of bilateral and synchronous spike and wave discharges (SWDs) in an established genetic model of generalized epilepsy.

Aging↗
PubMed2000

Increased expression of mRNA encoding ferritin heavy chain in brain structures of a rat model of absence epilepsy.

Differential mRNA display was carried out to find genes that are differentially regulated in the brain of a rat strain with absence epilepsy, the genetic absence epilepsy rats from Strasbourg (GAERS). Among the 32 differentially displayed cDNA fragments actually cloned and sequenced, one shows 100% identity with the rat heavy chain ferritin (H-ferritin) mRNA. Northern blot analysis confirmed the up-regulation of the H-ferritin mRNA. Using dot blotting, a 40% increase in expression was reported in the subcortical forebrain of the adult GAERS, while cortex, brain stem, and cerebellum appeared unmodified. This change was not observed in the brain of 25-day-old rats, an age at which the epileptic phenotype is not present. By in situ hybridization, the enhanced expression was localized in the hippocampus. The increase in mRNA encoding H-ferritin was not immunodetected at the protein level by Western blotting. These results are not apparently related to the neural substrate of SWD or to the distribution of local increase in glucose metabolism previously described in the GAERS. It is hypothesized that the up-regulation of the H-ferritin mRNA is part of a mechanism protecting the hippocampus, a seizure-prone area, against a possible overactivation during absence seizures.

Age Factors↗
PubMedDate not supplied

Acute vagus nerve stimulation does not suppress spike and wave discharges in genetic absence epilepsy rats from Strasbourg.

We evaluated the efficacy of vagus nerve stimulation (VNS) in Genetic Absence Epilepsy Rats from Strasbourg (GAERS), a validated model for absence epilepsy. In the first experiment, we investigated whether VNS applied at seizure onset can interrupt spike and wave discharges (SWD). In the second experiment, we investigated whether SWD are suppressed or shortened in duration when VNS is applied several hours per day. Both control and VNS groups underwent EEG and VNS electrode implantation. For the first experiment, a randomized crossover design was used. Stimuli (amplitude: 3 V; frequency: 30 Hz; pulse duration: 500 micros) were given when an SWD occurred on the EEG. The experiment was repeated the next day. In the second experiment, treated animals were stimulated (amplitude: 1.5 mA; frequency: 30 Hz; pulse duration: 500 micros; on/off time cycle: 30 s / 5 min) for 3h per day, during five consecutive days. In the first experiment, the duration of the SWD was increased on day 1, (P < 0.05). There was no difference in SWD duration on Day 2. In the second experiment, no significant differences could be found in number, duration and EEG frequency of SWD. VNS applied at the onset of an SWD can prolong the duration of SWD in GAERS. As a 5-day stimulation protocol had no effect, long-term VNS might be necessary to affect SWD.

Action Potentials↗
PubMed2004

Chromosomal mapping of genetic loci controlling absence epilepsy phenotypes in the WAG/Rij rat.

PURPOSE: The WAG/Rij rat is among the most appropriate models for the study of spontaneous childhood absence epilepsy, without complex neurologic disorders that are associated with some mouse models for absence epilepsy. Previous studies have allowed the identification of distinct types of spike-wave discharges (SWDs) characterizing seizures in this strain. The purpose of this study was to investigate the genetic basis of electroencephalographic (EEG) properties of SWDs. METHODS: An intercross was derived from WAG/Rij and ACI inbred strains that are known to differ substantially in the number of SWDs. Phenotypic analyses based on 23-h EEG recording in all progenies allowed the quantification of type I and type II SWD phenotypes. A genome-wide scan was performed with 145 microsatellite markers, which were used to test for evidence of genetic linkage to SWD quantitative phenotypes. RESULTS: We were able to map quantitative trait loci independently, controlling type I and type II SWD variables to rat chromosomes 5 and 9. Strongest linkages were obtained for D5Mgh15 and total duration of type II SWD (lod, 3.64) and for D9Rat103 and the average duration of type I SWD (lod, 3.91). These loci were denoted T2swd/wag and T1swd/wag, respectively. CONCLUSIONS: The independent genetic control of type I and type II SWDs underlines the complexity of the molecular mechanisms participating in SWDs. The identification of these genetic loci represents an important step in our fundamental knowledge of the architecture of SWDs and may provide new insights for resolving the genetic heterogeneity of absence epilepsy.

Animals↗
PubMed2003

[Association of child absence epilepsy with T-STAR gene].

OBJECTIVE: To investigate the Association of child absence epilepsy with T-STAR gene. METHODS: PCR was conducted on the DNA of peripheral blood white cells from 48 children with child absence epilepsy (CAE), 47 male and 49 female, aged 2.9 approximately 14, of Han nationality in Northern China and 48 healthy children in the same area to amplify the exons of T-STAR gene The PCR products underwent sequencing to identify the possible mutations. RESULTS: No mutation was found in the exons of the T-STAR gene, however, 3 single nucleotide polymorphisms (SNPs) were found. A case-control study was carried out, using SNP1 and SNP2. There was no significant difference in genotype frequency of the 2 SNPs between the CAE group and control group (SNA1: chi(2) = 2.965, df = 1, P = 0.085; SNP2: chi(2) = 2.965, df = 1, P = 0.085). There was no significant difference in allele frequency of the 2 SNPs between the CAE group and control group too (SNA1: chi(2) = 3.185, df = 2, P = 0.203; SNP2: chi(2) = 3.185, df = 2, P = 0.203). CONCLUSION: T-STAR may not be a susceptibility gene for CAE in Chinese populations.

Adolescent↗
PubMed1992

Genetic models of absence epilepsy, with emphasis on the WAG/Rij strain of rats.

In this review, the main characteristics of genetic models of absence epilepsy, in particular with respect to WAG/Rij rats, are presented. Genetic models are important and relevant, since evidence exists that these models mimic spontaneously occurring human epilepsy more than models in which epilepsy is artificially induced. Genetic models can be divided into models in which seizures are elicited and into those in which epilepsy appears without any sensory stimulation. The majority of genetic models show that absence type of epilepsy; during the last few years, we and others have noticed that rats of various strains exhibit spontaneously occurring spike-wave discharges in the EEG. Among the strains highly affected is the WAG/Rij strain, which is a fully inbred strain. Individuals are homozygous and because of this property, genetic studies are meaningful. Electrophysiological studies have indicated that abnormal discharges in the cortical EEG are generalized and that the hippocampus is not involved. Parts of the thalamus, together with the thalamic reticular nucleus, apparently act as a pacemaker for the abnormal discharges. There is a circadian modulation in the number of spike-wave discharges. Discharges mainly occur during intermediate levels of vigilance such as passive wakefulness and light slow-wave sleep and at transitions of sleep states. Pharmacological studies with clinically effective antiepileptic drugs have shown a close agreement in seizure response between man and rat. Studies with new compounds have emphasized the role of the GABAergic and glutamatergic system in this type of epilepsy. Particularly striking is the role of the GABAergic system. GABA agonists enhance and GABA antagonists reduce the occurrence of spike-wave discharges, which deviates from the effects of GABAergic drugs in non-convulsive epilepsy. Even more striking is the role of the benzodiazepines, generally seen as GABA agonists; these drugs do not act as such in absence epilepsy since they reduce spike-wave discharges. Also good evidence for an involvement of other neurotransmitters such as noradrenaline, dopamine and opioid peptides exists in absence epilepsy. Genetic data obtained from the WAG/Rij model for absence epilepsy show a relatively simple pattern of inheritance with one gene determining whether an individual is epileptic or not, and with other genes regulating the number and duration of seizures. This is in good agreement with the more restricted human data. Cognitive studies have shown two important features of epilepsy in the WAG/Rij strain: modulation of the number of spike-wave discharges by mental or physical activity and on the other hand, the disruption of cognitive activity by spike-wave discharges.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed2006

[Research on genes susceptible to childhood absence epilepsy].

Despite a few genes that do not encode ion channels have been identified as implicating some kinds of human idiopathic epilepsies(IE) in recent years, but genetic discoveries have shown the ion channels to play a central role in genetic pathomechanism of IE. The gene mutations of ion channels are a common cause of some rare monogenic IE which could be so-called as channelopathies, and able to be applied to account for the questioned epileptic syndrome to minority of families and sporadic cases. However, more frustrating has been from the genetic research on more common IE with complex inheritance due to the unknown mode of inheritance, the phenotypic heterogeneity and the uncertainty of genetic overlap among syndrome subtypes, which have limited gene mapping. Absence epilepsy is a kind of common IE subtype and shows a complex way to inherit. Evidences from heredity investigation indicate that eleven genes are correlated with absence epilepsy, of which four encode the neuronal calcium channel subunits. Therefore, calcium channel genes may be considered as important candidates for involving in absence epilepsy. To focus the genetics research on calcium channel genes of absence epilepsy may be opening an optimal gate to the pathogenetic study of more common IE with complex inheritance, and benefit to elucidate the molecular mechanisms of absence epilepsy finally, one of the more common IE subtypes with complex inheritance.

Calcium↗
PubMedDate not supplied

Social adjustment in young adults with absence epilepsies.

A long-term follow-up of 58 young adults, aged 18-27 years, with persisting absence epilepsies since childhood or early adolescence, was performed to assess psychosocial outcome and the patients' own concept of their epilepsy. They were well adjusted in the areas of family status and employment, but had more unqualified jobs as compared with a reference group. They were also inclined to lead very regular lives in a way that led to social isolation. At least one of the following factors was considered by 74% of the group to have been affected by their epilepsy: schooling, occupation, routines of daily life, relations with friends, leisure time activities, and housing, this was independent of whether or not they had achieved seizure control. In treating absence epilepsies, it is important that one considers psychosocial aspects, even if a medically satisfying result with seizure control is obtained.

Activities of Daily Living↗