Neuroendocrine changes in the hypothalamic-neurohypophysial system in the Wistar audiogenic rat (WAR) strain submitted to audiogenic kindling.

The Wistar audiogenic rat (WAR) strain is used as an animal model of epilepsy, which when submitted to acute acoustic stimulus presents tonic-clonic seizures, mainly dependent on brainstem (mesencephalic) structures. However, when WARs are exposed to chronic acoustic stimuli (audiogenic kindling-AK), they usually present tonic-clonic seizures, followed by limbic seizures, after recruitment of forebrain structures such as the cortex, hippocampus and amygdala. Although some studies have reported that hypothalamic-hypophysis function is also altered in WAR through modulating vasopressin (AVP) and oxytocin (OXT) secretion, the role of these neuropeptides in epilepsy still is controversial. We analyzed the impact of AK and consequent activation of mesencephalic neurocircuits and the recruitment of forebrain limbic (LiR) sites on the hypothalamic-neurohypophysial system and expression of Avpr1a and Oxtr in these structures. At the end of the AK protocol, nine out of 18 WARs presented LiR. Increases in both plasma vasopressin and oxytocin levels were observed in WAR when compared to Wistar rats. These results were correlated with an increase in the expressions of heteronuclear (hn) and messenger (m) RNA for Oxt in the paraventricular nucleus (PVN) in WARs submitted to AK that presented LiR. In the paraventricular nucleus, the hnAvp and mAvp expressions increased in WARs with and without LiR, respectively. There were no significant differences in Avp and Oxt expression in supraoptic nuclei (SON). Also, there was a reduction in the Avpr1a expression in the central nucleus of the amygdala and frontal lobe in the WAR strain. In the inferior colliculus, Avpr1a expression was lower in WARs after AK, especially those without LiR. Our results indicate that both AK and LiR in WARs lead to changes in the hypothalamic-neurohypophysial system and its receptors, providing a new molecular basis to better understaind epilepsy.

Age-Dependent and Sleep/Seizure-Induced Pathomechanisms of Autosomal Dominant Sleep-Related Hypermotor Epilepsy.

The loss-of-function S284L-mutant α4 subunit of the nicotinic acetylcholine receptor (nAChR) is considered to contribute to the pathomechanism of autosomal dominant sleep-related hypermotor epilepsy (ADSHE); however, the age-dependent and sleep-related pathomechanisms of ADSHE remain to be clarified. To explore the age-dependent and sleep-induced pathomechanism of ADSHE, the present study determined the glutamatergic transmission abnormalities associated with α4ß2-nAChR and the astroglial hemichannel in the hyperdirect and corticostriatal pathways of ADSHE model transgenic rats (S286L-TG) bearing the rat S286L-mutant Chrna4 gene corresponding to the human S284L-mutant CHRNA4 gene of ADSHE, using multiprobe microdialysis and capillary immunoblotting analyses. This study could not detect glutamatergic transmission in the corticostriatal pathway from the orbitofrontal cortex (OFC) to the striatum. Before ADSHE onset (four weeks of age), functional abnormalities of glutamatergic transmission compared to the wild-type in the cortical hyperdirect pathway, from OFC to the subthalamic nucleus (STN) in S286L-TG, could not be detected. Conversely, after ADSHE onset (eight weeks of age), glutamatergic transmission in the hyperdirect pathway of S286L-TG was enhanced compared to the wild-type. Notably, enhanced glutamatergic transmission of S286L-TG was revealed by hemichannel activation in the OFC. Expression of connexin43 (Cx43) in the OFC of S286L-TG was upregulated after ADSHE onset but was almost equal to the wild-type prior to ADSHE onset. Differences in the expression of phosphorylated protein kinase B (pAkt) before ADSHE onset between the wild-type and S286L-TG were not observed; however, after ADSHE onset, pAkt was upregulated in S286L-TG. Conversely, the expression of phosphorylated extracellular signal-regulated kinase (pErk) was already upregulated before ADSHE onset compared to the wild-type. Both before and after ADSHE onset, subchronic nicotine administration decreased and did not affect the both expression of Cx43 and pErk of respective wild-type and S286L-TG, whereas the pAkt expression of both the wild-type and S286L-TG was increased by nicotine. Cx43 expression in the plasma membrane of the primary cultured astrocytes of the wild-type was increased by elevation of the extracellular K+ level (higher than 10 mM), and the increase in Cx43 expression in the plasma membrane required pErk functions. These observations indicate that a combination of functional abnormalities, GABAergic disinhibition, and upregulated pErk induced by the loss-of-function S286L-mutant α4ß2-nAChR contribute to the age-dependent and sleep-induced pathomechanism of ADSHE via the upregulation/hyperactivation of the Cx43 hemichannels.

Analysis of gene variants in the GASH/Sal model of epilepsy.

Epilepsy is a complex neurological disorder characterized by sudden and recurrent seizures, which are caused by various factors, including genetic abnormalities. Several animal models of epilepsy mimic the different symptoms of this disorder. In particular, the genetic audiogenic seizure hamster from Salamanca (GASH/Sal) animals exhibit sound-induced seizures similar to the generalized tonic seizures observed in epileptic patients. However, the genetic alterations underlying the audiogenic seizure susceptibility of the GASH/Sal model remain unknown. In addition, gene variations in the GASH/Sal might have a close resemblance with those described in humans with epilepsy, which is a prerequisite for any new preclinical studies that target genetic abnormalities. Here, we performed whole exome sequencing (WES) in GASH/Sal animals and their corresponding controls to identify and characterize the mutational landscape of the GASH/Sal strain. After filtering the results, moderate- and high-impact variants were validated by Sanger sequencing, assessing the possible impact of the mutations by "in silico" reconstruction of the encoded proteins and analyzing their corresponding biological pathways. Lastly, we quantified gene expression levels by RT-qPCR. In the GASH/Sal model, WES showed the presence of 342 variations, in which 21 were classified as high-impact mutations. After a full bioinformatics analysis to highlight the high quality and reliable variants, the presence of 3 high-impact and 15 moderate-impact variants were identified. Gene expression analysis of the high-impact variants of Asb14 (ankyrin repeat and SOCS Box Containing 14), Msh3 (MutS Homolog 3) and Arhgef38 (Rho Guanine Nucleotide Exchange Factor 38) genes showed a higher expression in the GASH/Sal than in control hamsters. In silico analysis of the functional consequences indicated that those mutations in the three encoded proteins would have severe functional alterations. By functional analysis of the variants, we detected 44 significantly enriched pathways, including the glutamatergic synapse pathway. The data show three high-impact mutations with a major impact on the function of the proteins encoded by these genes, although no mutation in these three genes has been associated with some type of epilepsy until now. Furthermore, GASH/Sal animals also showed gene variants associated with different types of epilepsy that has been extensively documented, as well as mutations in other genes that encode proteins with functions related to neuronal excitability, which could be implied in the phenotype of the GASH/Sal. Our findings provide valuable genetic and biological pathway data associated to the genetic burden of the audiogenic seizure susceptibility and reinforce the need to validate the role of each key mutation in the phenotype of the GASH/Sal model.

Time course of transient expression of pre-α-pro-GDNF and pre-ß-pro-GDNF transcripts, and mGDNF mRNA region in Krushinsky-Molodkina rat brain after audiogenic seizures.

The expression of glial cell line-derived neurothrophic factor (GDNF) transcript forms pre-(α)pro-gdnf, pre-(ß)pro-gdnf, and their common region m-gdnf in the pons as well as the inferior (IC) and superior colliculi in Krushinsky-Molodkina (KM) rats and in the strain "0" was analyzed by quantitative real-time polymerase chain reaction (PCR) in the control (unstimulated KM and "0" rats) and 1.5, 4.5, and 8 h after auditory stimulation. Such stimulation induced audiogenic seizures (AS) in KM rats. Audiogenic seizure was not observed in "0" rats, which was obtained by selection for the absence of AS in a population of F2 hybrids between KM and Wistar rats not predisposed to AS. A significant drop in the level of all transcripts was observed 1.5 h after auditory stimulation in both KM and "0" rats. In most cases, the average expression of α and ß isoforms and m-region 4.5 h after stimulation was greater than those after 1.5 and 8 h. At the same time, the expression of pre-(ß)pro-gdnf in the IC of KM rats 4.5 h after the stimulation was significantly lower than after 1.5 or 8 h. This work presents the first demonstration of different time courses of expression of the α and ß GDNF isoforms during physiological processes in genotype-specific pathology.

Apoptosis and proliferation in the inferior colliculus during postnatal development and epileptogenesis in audiogenic Krushinsky-Molodkina rats.

It is known that audiogenic seizure (AGS) expression is based on the activation of the midbrain structures such as the inferior colliculus (IC). It was demonstrated that excessive sound exposure during the postnatal developments of the IC in rats led to AGS susceptibility in adulthood, which correlated with underdevelopment of the IC. In adult rodents, noise overstimulation induced apoptosis in the IC. The purpose of this study was to investigate postnatal development of the IC in rats genetically prone to AGS and to check if audiogenic kindling would activate apoptosis and/or proliferation in the IC. In our study, we used inbred audiogenic Krushinsky-Molodkina (KM) rats, which are characterized by age-dependent seizure expression. Analysis of postnatal development showed the increased number of proliferating cells in the IC central nucleus of KM rats on the 14th postnatal day (P14) in comparison with those of Wistar rats. Moreover, we also observed increased apoptosis level and decreased general cell population in the IC central nucleus. These data pointed towards a delayed development of the IC in KM rats. Analysis of the IC central nucleus of KM rat after audiogenic kindling for a week, with one AGS per day, demonstrated dramatically increased cell death, which was accompanied with a reduction of general cell population. Audiogenic kindling also decreased proliferation in the IC central nucleus. However, a week after the last AGS, the number of proliferating cells was increased, which supposes a certain compensatory mechanism to prevent cell loss.

Transcriptome of the Wistar audiogenic rat (WAR) strain following audiogenic seizures.

The Wistar Audiogenic Rat (WAR) is a model whose rats are predisposed to develop seizures following acoustic stimulation. We aimed to establish the transcriptional profile of the WAR model, searching for genes that help in understanding the molecular mechanisms involved in the predisposition and seizures expression of this strain. RNA-Seq of the corpora quadrigemina of WAR and Wistar rats subjected to acoustic stimulation revealed 64 genes differentially regulated in WAR. We validated twelve of these genes by qPCR in stimulated and naive (non-stimulated) WAR and Wistar rats. Among these, Acsm3 was upregulated in WAR in comparison with both control groups. In contrast, Gpr126 and Rtel1 were downregulated in naive and stimulated WAR rats in comparison with the Wistar controls. Qdpr was upregulated only in stimulated WAR rats that exhibited audiogenic seizures. Our data show that there are genes with differential intrinsic regulation in the WAR model and that seizures can alter gene regulation. We identified new genes that might be involved in the epileptic phenotype and comorbidities of the WAR model.

Intrinsic and synaptic properties of hippocampal CA1 pyramidal neurons of the Wistar Audiogenic Rat (WAR) strain, a genetic model of epilepsy.

Despite the many studies focusing on epilepsy, a lot of the basic mechanisms underlying seizure susceptibility are mainly unclear. Here, we studied cellular electrical excitability, as well as excitatory and inhibitory synaptic neurotransmission of CA1 pyramidal neurons from the dorsal hippocampus of a genetic model of epilepsy, the Wistar Audiogenic Rat (WARs) in which limbic seizures appear after repeated audiogenic stimulation. We examined intrinsic properties of neurons, as well as EPSCs evoked by Schaffer-collateral stimulation in slices from WARs and Wistar parental strain. We also analyzed spontaneous IPSCs and quantal miniature inhibitory events. Our data show that even in the absence of previous seizures, GABAergic neurotransmission is reduced in the dorsal hippocampus of WARs. We observed a decrease in the frequency of IPSCs and mIPSCs. Moreover, mIPSCs of WARs had faster rise times, indicating that they probably arise from more proximal synapses. Finally, intrinsic membrane properties, firing and excitatory neurotransmission mediated by both NMDA and non-NMDA receptors are similar to the parental strain. Since GABAergic inhibition towards CA1 pyramidal neurons is reduced in WARs, the inhibitory network could be ineffective to prevent the seizure-dependent spread of hyperexcitation. These functional changes could make these animals more susceptible to the limbic seizures observed during the audiogenic kindling.

Audiogenic Epilepsy and Structural Features of Superior Colliculus in KM Rats.

Using immunoblotting, we showed that in rats of audiogenic epilepsy (AE) prone strain (Krushinsky- Molodkina, KM) the superior colliculus tissue (SC) contains significantly less quantity of glial neurotrophic factor (GDNF), beta-tubulin and actin in comparison to the same brain region in "0" rats, nonprone to AE. This fact led to the suggestion that the histological structure of the SC in KM rats could differ significantly from that of the "0" strain. Using neuromorphologу technique, we demonstrated that the total number of SC cells, as well as the number of neurons were significantly less in KM rats than in the "0" strain rats. Particularly strong differences were found in the deep layers of SC, the area of terminals from IC. Further studies of the midbrain structures, will help to identify the novel aspects of neural networks, involved in the genesis of AE in rats of KM strain.

Photosensitivity and epilepsy: Current concepts and perspectives-A narrative review.

The authors review the influence of photic stimuli on the generation of epileptic seizures, addressing the first descriptions of the phenomenon and its subsequent exploration. Initially defined in the 1950's, links between intermittent photic stimulation (IPS) and seizures were well understood by the 1970. Since then the increasing exposure to photic stimuli associated with modern life (for instance through TVs, patterns, computer games and electronic instruments with flickering displays) has led to an increased interest in this issue. Diverse stimulation procedures have been described and difference in the effects of stimulation frequencies and types, colour and lighting have been recognised. Approximately 5% of patients with epilepsy have photosensitive epilepsy (PSE). PSE is commoner in younger individuals, more frequent in women, often time-limited, generally easy to treat and closely related to generalised epilepsies, especially Juvenile Myoclonic Epilepsy (JME). Structural and functional studies of PSE indicate abnormalities beyond the frontal lobes and evidence for the role of the visual cortex in human PSE. A reduction in connectivity between prefrontal and frontopolar regions and increased connectivity between occipital cortex and the supplementary motor area may be the basis for triggering motor seizures in JME. Due to the changes observed in such areas, it is hypothesised that photoparoxysmal responses (PPR) could be a final expression of pathogenic phenomena in the striato-thalamocortical system, and possibly a core feature of JME as system epilepsy. The familial transmission of epileptiform responses to IPS is well-recognised, but no clear relation between PSE and specific genes has emerged. Although the influence of ethnic factors on PSE has been widely studied, clear conclusions are still lacking. Pharmacological therapeutic approaches are beyond the scope of this review although preventive measures allowing patients to avoid PS seizure initiation and/or generalisation are discussed. Given the gender/age group most commonly affected by PSE, the risks and benefits of drug treatment need to be carefully weighed up.

Audiogenic seizure activity following HSV-1 GAD65 sense or antisense injection into inferior colliculus of Long-Evans rat.

Herpes virus technology involving manipulation of GAD65 was used to study effects on audiogenic seizures (AGS). Audiogenic seizure behaviors were examined following injections of replication-defective herpes simplex virus (HSV-1) vectors incorporating sense or antisense toward GAD65 along with 10% lac-Z into the central nucleus of inferior colliculus (CNIC) of Long-Evans rats. In seizure-sensitive animals developmentally primed by intense sound exposure, injection of GAD65 in the sense orientation increased wild running latencies and reduced incidence of clonus compared with lac-Z only, unoperated, and vehicle seizure groups. In contrast, infection of CNIC with GAD65 antisense virus resulted in 100% incidence of wild running and clonus behaviors in AGS animals. Unprimed animals not operated continued to show uniform absence of seizure activity. Administration of GAD65 antisense virus into CNIC produced novel wild running and clonus behaviors in some unprimed animals. Staining for ß-galactosidase in all vector animals revealed no differences in pattern or numbers of immunoreactive cells at injection sites. Qualitatively, typical small and medium multipolar/stellate and medium fusiform neurons appeared in the CNIC of vector animals. These results demonstrate that HSV-1 vector constructs implanted into the CNIC can predictably influence incidence and severity of AGS and suggest that viral vectors can be useful in studying GABA mechanisms with potential for therapeutic application in epilepsy. This article is part of a Special Issue entitled "Genetic and Reflex Epilepsies, Audiogenic Seizures and Strains: From Experimental Models to the Clinic".

Features of stimulus-specific seizures in dogs with reflex epilepsy: 43 cases (2000-2014).

OBJECTIVE To describe the occurrence and management of reflex epilepsy (ie, seizure activity triggered by exposure to specific locations or situations) in dogs. DESIGN Retrospective case series. ANIMALS 43 client-owned dogs. PROCEDURES Discussions by veterinarians participating in the Veterinary Information Network online community for the years 2000 through 2014 were reviewed to identify dogs with a diagnosis of reflex epilepsy and seizure activity in response to stimuli. History, signalment (including age at onset), the specific stimulus or stimuli that provoked seizures, treatments, and any concurrent neurologic diagnoses were recorded. RESULTS A variety of breeds were affected. Median age at onset was 5 years (range, 3 months to 11 years). Reflex seizures were reported as being repeatedly triggered by visits to a veterinary clinic (35/43 dogs), grooming facility (24/43 dogs), or boarding facility (13/43 dogs) and, less commonly, by other situations (eg, pet store or car ride). Over half of the dogs (24/43) had multiple triggers. Eight (19%) dogs had seizures at other times that were not induced by location or a specific situation. A variety of sedatives and maintenance antiepileptic drugs administered to affected dogs failed to prevent the stimulus-specific seizure activity. CONCLUSIONS AND CLINICAL RELEVANCE Results of the present study suggested that seizures provoked by specific situations or locations occur in dogs with reflex epilepsy and that common triggers were visits to veterinary and grooming facilities. Further studies are necessary to elucidate the characteristics of reflex epilepsy in dogs and to determine the most effective means to manage these patients.

An abnormal GABAergic system in the inferior colliculus provides a basis for audiogenic seizures in genetically epilepsy-prone rats.

In this review of neuroanatomical studies of the genetically epilepsy-prone rat (GEPR), three main topics will be covered. First, the number of GABAergic neurons and total neurons in the inferior colliculus of GEPRs will be compared to those of the nonepileptic Sprague-Dawley rat. Next, the number of small neurons in the inferior colliculus will be described in both developmental and genetic analyses of GEPRs and their backcrosses. Last, results from two types of studies on the propagation pathways for audiogenic seizures in GEPRs will be shown. Together, these studies demonstrate a unique GABAergic, small neuron defect in the inferior colliculus of GEPRs that may play a vital role in the initiation and spread of seizure activity during audiogenic seizures. This article is part of a Special Issue entitled "Genetic and Reflex Epilepsies, Audiogenic Seizures and Strains: From Experimental Models to the Clinic".

Morphofunctional alterations in the olivocochlear efferent system of the genetic audiogenic seizure-prone hamster GASH:Sal.

The genetic audiogenic seizure hamster (GASH:Sal) is a model of a form of reflex epilepsy that is manifested as generalized tonic-clonic seizures induced by external acoustic stimulation. The morphofunctional alterations in the auditory system of the GASH:Sal that may contribute to seizure susceptibility have not been thoroughly determined. In this study, we analyzed the olivocochlear efferent system of the GASH:Sal from the organ of Corti, including outer and inner hair cells, to the olivocochlear neurons, including shell, lateral, and medial olivocochlear (LOC and MOC) neurons that innervate the cochlear receptor. To achieve this, we carried out a multi-technical approach that combined auditory hearing screenings, scanning electron microscopy, morphometric analysis of labeled LOC and MOC neurons after unilateral Fluoro-Gold injections into the cochlea, and 3D reconstruction of the lateral superior olive (LSO). Our results showed that the GASH:Sal exhibited higher auditory brain response (ABR) thresholds than their controls, as well as absence of distortion-product of otoacoustic emissions (DPOAEs) in a wide range of frequencies. The ABR and DPOAE results also showed differences between the left and right ears, indicating asymmetrical hearing alterations in the GASH:Sal. These alterations in the peripheral auditory activity correlated with morphological alterations. At the cochlear level, the scanning electron microscopy analysis showed marked distortions of the stereocilia from basal to apical cochlear turns in the GASH:Sal, which were not observed in the control hamsters. At the brainstem level, MOC, LOC, and shell neurons had reduced soma areas compared with control animals. This LOC neuron shrinkage contributed to reduction in the LSO volume of the GASH:Sal as shown in the 3D reconstruction analysis. Our study demonstrated that the morphofunctional alterations of the olivocochlear efferent system are innate components of the GASH:Sal, which might contribute to their susceptibility to audiogenic seizures. This article is part of a Special Issue entitled "Genetic and Reflex Epilepsies, Audiogenic Seizures and Strains: From Experimental Models to the Clinic".

H1 histamine receptor densities are increased in brain regions of rats with genetically generalized epilepsies.

Genetic animal models for convulsive, non-convulsive and mixed types of generalized epilepsies were used to establish putative histaminergic brain sites involved in the control of different types of epilepsy. Age matched rats of the KM strain (audiogenic seizures, AGS), WAG/Rij strain (absence seizures) and the WAG/Rij-AGS substrain (mixed model) were compared with a control group of Wistar rats on regional binding densities of H1 histamine receptors. Coronal slices of adult brains of the four groups were labeled with 3H pyrilamine, an antagonist of H1 histamine receptor and density of receptors was quantified with image analyses. All three groups of epileptic rats showed an increase in the density of H1 histamine receptor binding in the frontal motor cortex and interposed nucleus of cerebellum compared to the non-epileptic control group. Audiogenic epilepsy was characterized by increased H1 histamine receptor density in the frontal cortical and hippocampal regions, and in two midbrain (interpedunculus and lateral vestibular) nuclei. Absence epilepsy was characterized by a decrease in substantia nigra pars compacta, while the mixed model showed an elevation of H1 histamine receptor binding density in limbic regions such as the shell of the nucleus accumbens and the ventral tegmental area. It can be concluded that common changes in H1 histamine receptors can be found in genetic epilepsy models irrespective of the seizure type, and that each type of generalized epilepsy has its own pattern of H1 histamine receptor changes. It is speculated that H1 histamine receptors play a role in the brain's endogenous epilepsy control system.

Lack of Chronic Histologic Lesions Supportive of Sublethal Spontaneous Seizures in FVB/N Mice.

FVB/N mice with 'space cadet' syndrome are prone to audiogenic seizures and are considered excitotoxic 'sensitive' mice due to the neuronal damage that accompanies seizures. FVB/N mice found dead demonstrate acute neuronal cell death--attributed to a massive seizure episode--within the hippocampus and cerebrocortical laminae. However, the behavioral features of FVB/N mice and numerous studies using excitotoxins to induce seizure activity indicate that this strain experiences multiple sublethal seizures. To assess whether FVB/N mice develop histologically detectable lesions, we evaluated the brains of 86 aged (154-847 d) FVB/N mice without a history of seizures. The hippocampus and cerebrocortical laminae were evaluated histologically for neuronal atrophy and gliosis. Neuronal atrophy was quantified by counting neurons in the hippocampus (CA3 and dentate gyrus) and cerebral cortex. Gliosis was quantified by using immunohistochemistry for glial fibrillary acidic protein and glial counting in the cerebral cortex. In addition, ventricular area was calculated. Our study revealed no changes in brain weight with age, no neuronal loss or gliosis, no correlation between neuronal or glial cell profile densities and brain weight or age, and no differences in ventricular size between FVB/N and control mice. Neuronal densities in the cerebral cortex and granule cells of the dentate gyrus were lower in FVB/N mice than in control Swiss Webster mice. We conclude that although acute lesions of seizure activity are a previous feature of the FVB/N strain, chronic seizure activity in these mice either is negligible or does not cause morphologic or phenotypic changes.

Optical coherence tomography parameters in patients with photosensitive juvenile myoclonic epilepsy.

PURPOSE: Juvenile myoclonic epilepsy (JME) is commonly associated with photoparoxysmal response (PPR) with a reported prevalence of 25-42%. In this study, we aim to explore the relationship between the PPR and Optical Coherence Tomography (OCT) parameters in order to determine whether optic nerve fiber layer or other structural differences have a pathophysiological role of photosensitivity in patients with JME. METHODS: We studied 53 consecutive patients with Juvenile myoclonic epilepsy (JME) at our outpatient department. The interictal electroencephalogram (EEG) findings for each patient were analyzed for the presence of photoparoxysmal features. The peripapillary Retina Nerve Fiber Layer (RNFL) thickness, ganglion cell thickness, macular thickness and choroid thickness levels were analyzed using OCT. RESULTS: We classified the patients into two groups as those with PPR (Group 1) and those without PPR (Group 2). There were statistically significant differences in the average RNFL thickness values of the left eye between the two groups (p<0.001). Although the RNFL thickness of the right eye was higher in Group 1, no statistically significant difference was observed between the two groups. The RFNL thickness of the superior quadrants both in the right and the left eyes was significantly higher in Group 1 patients (p<0.001). Macular thickness of the right and left eyes were significantly thinner in Group 1 patients (p<0.001). Choroid thickness of the left eye was significantly higher in Group 1 than in Group 2 patients (p<0.001). Although the choroid thickness of the right eye was higher in Group 1 patients, no statistically significant difference was observed between the two groups. CONCLUSION: This is the first study to our knowledge which has investigated the relation between the OCT parameters and photosensitivity in patients with JME. We concluded that these microstructural features may be related to photosensitivity in patients with JME.

Evaluation of Cardiovascular Risk Factors in the Wistar Audiogenic Rat (WAR) Strain.

INTRODUCTION: Risk factors for life-threatening cardiovascular events were evaluated in an experimental model of epilepsy, the Wistar Audiogenic Rat (WAR) strain. METHODS: We used long-term ECG recordings in conscious, one year old, WAR and Wistar control counterparts to evaluate spontaneous arrhythmias and heart rate variability, a tool to assess autonomic cardiac control. Ventricular function was also evaluated using the pressure-volume conductance system in anesthetized rats. RESULTS: Basal RR interval (RRi) was similar between WAR and Wistar rats (188 ± 5 vs 199 ± 6 ms). RRi variability strongly suggests that WAR present an autonomic imbalance with sympathetic overactivity, which is an isolated risk factor for cardiovascular events. Anesthetized WAR showed lower arterial pressure (92 ± 3 vs 115 ± 5 mmHg) and exhibited indices of systolic dysfunction, such as higher ventricle end-diastolic pressure (9.2 ± 0.6 vs 5.6 ± 1 mmHg) and volume (137 ± 9 vs 68 ± 9 µL) as well as lower rate of increase in ventricular pressure (5266 ± 602 vs 7320 ± 538 mmHg.s-1). Indices of diastolic cardiac function, such as lower rate of decrease in ventricular pressure (-5014 ± 780 vs -7766 ± 998 mmHg.s-1) and a higher slope of the linear relationship between end-diastolic pressure and volume (0.078 ± 0.011 vs 0.036 ± 0.011 mmHg.µL), were also found in WAR as compared to Wistar control rats. Moreover, Wistar rats had 3 to 6 ventricular ectopic beats, whereas WAR showed 15 to 30 ectopic beats out of the 20,000 beats analyzed in each rat. CONCLUSIONS: The autonomic imbalance observed previously at younger age is also present in aged WAR and, additionally, a cardiac dysfunction was also observed in the rats. These findings make this experimental model of epilepsy a valuable tool to study risk factors for cardiovascular events in epilepsy.

Long-term disease-modifying effect of the endocannabinoid agonist WIN55,212-2 in a rat model of audiogenic epilepsy.

BACKGROUND: Modulation of the endocannabinoid (eCB) transmission is a promising approach to treating epilepsy. Animal models can be used to investigate this approach. Krushinsky-Molodkina (KM) rats have, genetically, audiogenic epilepsy. Moreover, in these animals, repeated induction of audiogenic seizures results in a progressive prolongation of the seizures, known as audiogenic kindling. METHODS: The present study evaluated, in these KM rats, acute and long-term effects of a single dose of 4 mg/kg of the cannabinoid-receptor agonist WIN55,212-2. RESULTS: Administration of the single dose of WIN55,212-2 one hour before the 4th seizure delayed the kindling process by two weeks, without any acute effect on the audiogenic seizures. CONCLUSIONS: This result suggests that short-term potentiation of the eCB system might modify the epileptogenic disease process in patients with a progressive course of epilepsy.

Diffusion tensor imaging abnormalities in photosensitive juvenile myoclonic epilepsy.

BACKGROUND AND PURPOSE: Multiple structural white matter abnormalities have been described in patients with juvenile myoclonic epilepsy (JME). In the present study, the question of whether microstructural variations exist between the two subgroups of JME, with and without photoparoxysmal responses (PPR positive and negative), was addressed using diffusion tensor imaging. METHODS: A selection of 18 patients (eight PPR positive) from a tertiary epilepsy center diagnosed with JME and 27 healthy controls was studied. The following regions of interest were investigated: the ascending reticular activating system, lateral geniculate nucleus, genu of the internal capsule, ventromedial thalamus and inferior cerebellar peduncle. RESULTS: Widespread white matter microstructural abnormalities in JME and in particular in PPR positive cases were identified. PPR positive patients demonstrated increased fractional anisotropy in the ascending reticular activating system and ventromedial thalamus compared to PPR negative patients and healthy controls. Reduced fractional anisotropy of the lateral geniculate nucleus was observed in the entire JME group compared to healthy controls. CONCLUSIONS: Several microstructural variations between PPR positive and negative JME patients have been identified. Our findings highlight the pivotal role of the thalamus in the pathophysiology of primary generalized seizures and suggest that thalamo-premotor connections are both an essential part of epileptic networks and important in the pathogenesis of photosensitivity.

The expression and distribution of seizure-related and synaptic proteins in the insular cortex of rats genetically prone to audiogenic seizures.

It is known that perirhinal/insular cortices participate in the transmission of sensory stimuli to the motor cortex, thus coordinating motor activity during seizures. In the present study we analysed seizure-related proteins, such as GABA, glutamate, ERK1/2 and the synaptic proteins in the insular cortex of Krushinsky-Molodkina (KM) rats genetically prone to audiogenic seizures (AGS). We compared seizure-naïve and seizure-experienced KM rats with control Wistar rats in order to distinguish whether seizure-related protein changes are associated with seizure event or representing an inhered pathological abnormality that determines predisposition to AGS. Our data demonstrated an increased level of vesicular glutamate transporter VGLUT2 in naïve and seizure-experienced KM rats, while glutamic acid decarboxylases GAD65 and GAD67 levels were unchanged. Evaluation of the synaptic proteins showed a decrease in SNAP-25 and upregulation of synapsin I phosphorylation in both groups of KM rats in comparison to Wistar rats. However, when phosphorylation level of ERK1/2 in naïve KM rats was significantly increased, several episodes of AGS diminished ERK1/2 activity. Obtained data indicate that changes in ERK1/2 phosphorylation status and glutamate release controlling synaptic proteins in the insular cortex of KM rats could contribute to the AGS susceptibility.