Epileptic Seizures In Rats Research Articles

MicroRNA-27a-3p Downregulation Inhibits Inflammatory Response and Hippocampal Neuronal Cell Apoptosis by Upregulating Mitogen-Activated Protein Kinase 4 (MAP2K4) Expression in Epilepsy: In Vivo and In Vitro Studies.

BackgroundThis study aimed to discover the effect and mechanism of microRNA-27a-3p (miR-27a-3p) in epilepsy.Material/MethodsTo perform our investigation, in vivo and in vitro models of epilepsy were induced using kainic acid (KA). Expression of miR-27a-3p in the hippocampus of epileptic rats or normal rats or neuronal cells was detected using quantitative reverse transcription polymerase chain reaction (qRT-PCR). Racine score was used to assess seizures in epileptic rats. Cell viability and cell apoptosis were analyzed by 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide (MTT) assay and flow cytometry. Enzyme-linked immunosorbent assay (ELISA) was performed to detect inflammatory factors expression.ResultsSignificantly higher expression of miR-27a-3p in the hippocampus of epileptic rats and in KA-induced neurons was observed. We found that miR-27a-3p inhibitor alleviated seizures in epileptic rats. miR-27a-3p inhibitor also inhibited apoptosis of hippocampal neurons in epileptic rats, promoted Bcl2 expression, and decreased Bax and Caspase3 expression. The results showed that miR-27a-3p inhibitor effectively reduced the expression levels of interleukin-1β (IL-1β), IL-6, and tumor necrosis factor-α (TNF-α) in hippocampal tissues of epileptic rats. Dual luciferase reporter assay showed that mitogen-activated protein kinase 4 (MAP2K4) was a direct target of miR-27a-3p. miR-27a-3p inhibitor significantly promoted the cell viability of KA-induced neurons, inhibited cell apoptosis, promoted the expression of Bcl-2, and decreased Bax and Caspase3 expression, and all these changes were abolished by MAP2K4-siRNA co-transfection.ConclusionsOur preliminary findings indicated that miR-27a-3p inhibitor protected against epilepsy-induced inflammatory response and hippocampal neuronal apoptosis by targeting MAP2K4.

Wi-Fi decreases melatonin protective effect and increases hippocampal neuronal damage in pentylenetetrazole induced model seizures in rats

AimEpilepsy is a common brain disorder in which the seizures could cause a neuronal loss in the hippocampus. Oxidative stress has an important role in the pathology of epilepsy. Some studies indicate that Wi-Fi increases oxidative stress and suppresses antioxidant systems. The aim of this study is to investigate the effect of Wi-Fi on melatonin anticonvulsive effect and oxidative damage in pentylenetetrazole-induced epileptic seizures in rats. MethodsIn our study, we used 30 male Wistar Albino rats, 230−250 grams of the body weight. The animals were divided into five groups as control, saline (1 ml/kg/day olive oil for 30 days), Wi-Fi (12 h/day for 30 days), melatonin (10 mg/kg/day for 30 days) and melatonin + Wi-Fi (10 mg/kg/day +12 h/day for 30 days). In the thirtieth day, thirty minutes after the last drugs administration at the indicated doses, PTZ in 45 mg/kg was administered to induce epileptic seizure. The animals were observed for 30 min during the seizure stages (according to the Racine Scale) and first myoclonic jerk times (FMJ). Twenty-four hours after PTZ injection, brain tissues were removed for biochemical and histopathological evaluation. The hippocampal Cornu Ammonis (CA) 1, CA3 and DG (dentate gyrus) regions were histopathologically evaluated in terms of a neuronal damage in addition that oxidative stress markers (total antioxidant status (TAS), total oxidant status (TOS) and oxidative stress index (OSI)) were measured in brain tissues. ResultsWi-Fi was not found to affect behavioral changes associated with epilepsy (p > 0.05). However, Wi-Fi reduced anticonvulsive and antioxidant effect of melatonin (p < 0.05). Moreover, Wi-Fi increased neuronal damage in hippocampus (p < 0.05). ConclusionWi-Fi did not directly affect epileptic seizures. Nevertheless, it inhibits the positive effects of melatonin on epilepsy and it also has negative effects on hippocampal neuronal damage. These effects of Wi-Fi may occur via oxidative pathways.

Immune Profile in Blood Following Non-convulsive Epileptic Seizures in Rats.

Non-convulsive status epilepticus (NCSE) is a prolonged epileptic seizure with subtle symptoms that may delay clinical diagnosis. Emerging experimental evidence shows brain pathology and epilepsy development following NCSE. New diagnostic/prognostic tools are therefore needed for earlier and better stratification of treatment. Here we examined whether NCSE initiates a peripheral immune response in blood serum from rats that experienced electrically-induced NCSE. ELISA analysis showed an acute transient increase in serum protein levels including interleukin-6 6 h post-NCSE, similar to the immune reaction in the brain. At 4 weeks post-NCSE, when 75% of rats subjected to NCSE had also developed spontaneous seizures, several immune proteins were altered. In particular, markers associated with microglia, macrophages and antigen presenting cells, such as CD68, MHCII, and galectin-3, were increased and the T-cell marker CD4 was decreased in serum compared to both non-stimulated controls and NCSE rats without spontaneous seizures, without correlation to interictal epileptiform activity. Analyses of serum following intracerebral injection of lipopolysaccharide (LPS) showed an acute increase in interleukin-6, but at 4 weeks unaltered levels of MHCII and galectin-3, an increase in CD8 and CD11b and a decrease in CD68. None of the increased serum protein levels after NCSE or LPS could be confirmed in spleen tissue. Our data identifies the possibility to detect peripheral changes in serum protein levels following NCSE, which may be related to the development of subsequent spontaneous seizures.

Environmental Enrichment and Brain Neuroplasticity in the Kainate Rat Model of Temporal Lobe Epilepsy.

Background and PurposeEnvironmental enrichment (EE) improves brain function and ameliorates cognitive impairments; however, whether EE can reverse the learning and memory deficits seen following seizures remains unknown.MethodsWe tested the hypothesis that EE augments neurogenesis and attenuates the learning and memory deficits in rats subjected to kainate-induced seizures in hippocampus, amygdala and motor cortex. EE consisted of daily exposures immediately after KA lesioning (early EE) and after a 60-day period (late EE). Morphometric counting of neuron numbers (NN), dendritic branch-points and intersections (DDBPI) were performed. Spatial learning in a T-maze test was described as percent correct responses and memory in a passive-avoidance test was calculated as time spent in the small compartment where they were previously exposed to an aversive stimulus.ResultsEE increased NN and DDBPI in the normal control and in the KA-lesioned rats in all brain areas studied, after both early and late exposure to EE. Late EE resulted in significantly fewer surviving neurons than early EE in all brain areas (p < 0.0001). EE increased the percent correct responses and decreased time spent in the small compartment, after both early and late EE. The timing of EE (early vs. late) had no effect on the behavioral measurements.ConclusionsThese findings demonstrate that, after temporal lobe and motor cortex epileptic seizures in rats, EE improves neural plasticity in areas of the brain involved with emotional regulation and motor coordination, even if the EE treatment is delayed for 60 days. Future studies should determine whether EE is a useful therapeutic strategy for patients affected by seizures.

Neuroprotective effect of astaxanthin (ATX) against cognitive impairment on PTZ-induced epileptic seizures in rats and against PTZ-induced neurotoxicity in SH-SY5Y human neuroblastoma cell culture

Objective: Epilepsy is a common brain disorder that seizures could cause neuronal loss in the hippocampus. Oxidative stress has an important role in the pathology of this way. The aim of this study was to investigate the neuroprotective effect of astaxanthin (ATX), on pentylenetetrazole (PTZ) induced epileptic seizures in rats and in SH-SY5Y human neuroblastoma cell culture . Method: In our study, we used 42 male 230-250 g Wistar Albino rats. Animals were divided into seven groups as control, saline (PTZ; 1 ml/kg serum physiologic), positive control (2,5 mg/kg diazepam), 10 mg/kg, 20 mg/kg, 40 mg/kg and 80 mg/kg ATX for seven days. Thirty min after the administration of the last drug at the indicated doses, PTZ was administered 45 mg/kg to induce an epileptic seizure. The animals were observed for 30 min. Seizure stages according to the Racine Scale (RC) and first myoclonic jerk times (FMJ). Twenty four hours after PTZ injection, passive avoidance test was performed, and then brain tissues were removed for biochemical and histopathological evaluation. The hippocampal Cornu Ammonis 1 (CA1), CA3 and dentate gyrus (DG) regions were evaluated histopathologically regarding neuronal damage. Besides, oxidative stress markers total antioxidant status (TAS), total oxidant status (TOS) and oxidative stress index (OSI)) were measured in brain tissues. Furthermore, ATX was performed in vitro SH-SY5Y human neuroblastoma cell culture to evaluate PTZ-induced neurotoxicity. Results: When epileptic behaviors were evaluated, ATX did not affect RC and FMJ (p>0, 05). However, ATX reduced both cognitive impairment in passive avoidance test and neuronal damage in the hippocampus (p<0, 05). Moreover, ATX reduced both TOS levels and OSI in the brain (p<0, 05). Besides of these in vitro studies, ATX increased neuronal viability in vitro. Conclusions: Although ATX does not have antiepileptic properties directly, it has a protective effect on not only in vivo but also in vitro. These effects may occur by possible oxidative pathways.

Complex network based models of ECoG signals for detection of induced epileptic seizures in rats.

The automatic detection of seizures bears a considerable significance in epileptic diagnosis as it can efficiently lead to a considerable reduction of the workload of the medical staff. The present study aims at automatic detecting epileptic seizures in epileptic rats. To this end, seizures were induced in rats implementing the pentylenetetrazole model, with the electrocorticogram (ECoG) signals during, before and after the seizure periods being recorded. For this purpose, five algorithms for transforming time series into complex networks based on visibility graph (VG) algorithm were used. In this study, VG based methods were used for the first time to analyze ECoG signals in rats. Afterward, Standard measures in network science (graph properties) were made to examine the topological structure of these networks produced on the basis of ECoG signals. Then these measures were given to a classifier as input features so that the ECoG signals could be classified into seizure periods and seizure-free periods. Artificial Neural Network, considered a popular classifier, was used in this work. The experimental results showed that the method managed to detect epileptic seizure in rats with a high accuracy of 92.13%. Our proposed method was also applied to the recorded EEG signals from Bonn database to show the efficiency of the proposed method for human seizure detection.

Влияние вдыхания паров толуола на интенсивность аудиогенного судорожного припадка у крыс линии Крушинского–Молодкиной

Аctuality. The significant proportion of human epilepsy is resistant to anticonvulsant drug therapy, which makes actual the problem of search for new alternative antiepileptic therapies. The goal of this work was the analysis of the effects created by the inhalation of toluene vapor (the strong odorant) on epileptic seizures in rats of Krushinsky-Molodkina strain, which is highly prone to audiogenic epilepsy (AE), the tonic convulsions of the musculature as well as audiogenic myoclonic seizures which develop as the result of serial daily sound exposure. Methods. Rats (n=14) were exposed to 15-s inhalation of toluene vapor with the subsequent (in 20 s) testing of their audiogenic seizure intensity. Results. The toluene action induced a significant reduction in tonic and myoclonic seizure intensity in comparison to the background data of AE sensitivity obtained 1 week prior to the toluene test. In 13 of 14 animals, the seizures ended as the clonic seizures (no tonic seizures developed), while all animals developed tonic seizures in the “background” experiment. All rats developed myoclonic seizures (audiogenic kindling) prior to toluene action while no myoclonic seizures were noted after toluene inhalation in all animals. Conclusion. The results obtained complement the previously published data using WAR strain of rats on the relationship between epilepsy and olfactory system. The anticonvulsive effects of toluene vapor inhalation on the expression of AE signs demonstrate both the importance of genetic models usage in such investigations and the importance of olfactory stimulation as the potential anti-convulsant agent.

Overexpressed HspB6 Underlines a Novel Inhibitory Role in Kainic Acid-Induced Epileptic Seizure in Rats by Activating the cAMP-PKA Pathway.

Epilepsy is a commonly occurring neurological disease that has a large impact on the patient's daily life. Phosphorylation of heat shock protein B6 (HspB6) has been reported to protect the central nervous system. In this investigation, we explored whether HspB6 played a positive effect on epilepsy with the involvement of the cyclic adenosine monophosphate-protein kinase A (cAMP-PKA) pathway. The epileptic seizure was induced in rats by intraperitoneal injection of kainic acid (KA). The extent of HspB6 phosphorylation and expressions of HspB6, PKA, and inflammatory factors TNF-α, IL-1β, and IL-6 were quantified along with neuronal apoptosis. To further understand the regulatory mechanism of the HspB6 in the hippocampus, we altered the expression and the extent of HspB6 phosphorylation to see whether the cAMP-PKA pathway was inactivated or not in hippocampal neurons of rats post KA. Results showed that HspB6 was poorly expressed, resulting in the inactivation of the cAMP-PKA pathway in rats post KA, as well as an aggravated inflammatory response and hippocampal neuronal apoptosis. HspB6 overexpression and the cAMP-PKA pathway activation decreased the expression of inflammatory factors and inhibited hippocampal neuronal apoptosis. Additionally, HspB6 phosphorylation further augments the inhibitory effects of HspB6 on the inflammatory response and hippocampal neuronal apoptosis. The cAMP-PKA pathway activation was found to result in increased HspB6 phosphorylation. HspB6 decreased apoptosis signal-regulating kinase 1 (ASK1) expression to inhibit inflammatory response and hippocampal neuronal apoptosis. Collectively, our findings demonstrate that activation of the cAMP-PKA pathway induces overexpression and partial phosphorylation of HspB6 lead to the inhibition of ASK1 expression. This in turn protects rats against epilepsy and provides a potential approach to prevent the onset of epileptic seizure in a clinical setting.

Nrf2-ARE signaling pathway regulates the expressions of A1R and ENT1 in the brain of epileptic rats.

To explore the behavioral changes and the expressions of the A1 receptor (A1R) and balanced nucleoside transporter-1 (ENT1) in the brain of epileptic rats after activating the NF-E2-related factor 2 (Nrf2)-ARE signaling pathway. Adult male Sprague-Dawley (SD) rats were randomly divided into normal control group, epilepsy group, and t-butylhydroquinone (tBHQ) group, with 10 rats in each group. Lithium-pilocarpine induced epilepsy model in rats was established. The first epileptic latency and seizure frequency within 1 hour were observed in each group using the Racine scoring system. HE (Hematoxylin and Eosin) staining was used to observe the pathological lesions in the brain tissue of each group. The expressions of A1R, ENT1, and relative genes in Nrf2-ARE pathway in rat hippocampus was detected by immunohistochemistry and Western blot. Compared with rats in epileptic group, the first seizure latency was prolonged and the seizure frequency decreased in tBHQ group (p<0.05). The degree of brain lesions in tHBQ group was lighter than that of epilepsy group. ENT1 expression in rat hippocampus of epileptic group was significantly upregulated than that of normal control group and tBHQ group. Besides, the protein levels of A1R, Nrf2, HO-1, and ARE in rat hippocampus of epilepsy group markedly decreased compared with those of normal control group. However, protein expressions of A1R, Nrf2, HO-1, and ARE proteins in rat hippocampus of tBHQ group were markedly upregulated. Activation of the Nrf2-ARE signaling pathway can reduce the pathological damage of rat hippocampal neurons, prolong the latency of seizures, and reduce the degree of epileptic seizure in rats.

Electric Stimulation of Ear Reduces the Effect of Toll-Like Receptor 4 Signaling Pathway on Kainic Acid-Induced Epileptic Seizures in Rats.

Epilepsy is a common clinical syndrome with recurrent neuronal discharges in the temporal lobe, cerebral cortex, and hippocampus. Clinical antiepileptic medicines are often ineffective or of little benefit in 30% of epileptic patients and usually cause severe side effects. Emerging evidence indicates the crucial role of inflammatory mediators in epilepsy. The current study investigates the role of toll-like receptor 4 (TLR4) and its underlying mechanisms in kainic acid- (KA-) induced epileptic seizures in rats. Experimental KA injection successfully initiated an epileptic seizure accompanied by increased expression of TLR4 in the prefrontal cortex, hippocampus, and somatosensory cortex. In addition, calcium-sensitive phosphorylated Ca2+/calmodulin-dependent protein kinase II (pCaMKIIα) increased after the initiation of the epileptic seizure. Furthermore, downstream-phosphorylated signal-regulated kinase (ERK), c-Jun NH2-terminal protein kinase (JNK), and p38 kinase simultaneously increased in these brain areas. Moreover, the transcriptional factor phosphorylated nuclear factor-κB (pNF-κB) increased, suggesting that nucleus transcription was affected. Furthermore, the aforementioned molecules decreased by an electric stimulation (ES) of either 2 Hz or 15 Hz of the ear in the three brain areas. Accordingly, we suggest that ES of the ear can successfully control epileptic seizures by regulating the TLR4 signaling pathway and has a therapeutic benefit in reducing epileptic seizures.

Effect of the cyclooxygenase-2 inhibitor tenoxicam on pentylenetetrazole-induced epileptic seizures in rats

Amac: Epilepsi merkezi sinir sisteminde bir grup noronun ani, anormal ve hipersenkronize desarjlari ile nobetler halinde gozlenen beyin fonksiyonlarinin kisa sureli paroksimal rahatsizligi olarak tanimlanir. Nonsteroid anti inflamatuarlardan olan tenoksikam arasidonik asidi prostaglandinlere donusturen tip 2 siklooksijenaz (COX2) enzimini selektif olarak inhibe eden kimyasal bir ajandir. Bu calismanin amaci siklooksijenaz-2 inhibitoru tenoksikam'in pentilentetrazol ile olusturulan epileptik nobetlere uzerine etkisini arastirmaktir. Yontem: Calismamizda 18 tane 220-240 gr Wistar Albino erkek sican kullanilmistir. Hayvanlar kontrol (n=6), 10 mg/kg/gun tenoksikam (n=6) ve 20 mg/kg/gun tenoksikam (n=6) olmak uzere uc gruba ayrildi. On gun sure ile kontrol grubuna cozucu ve diger iki gruba belirtilen dozlarda tenoksikam intramuskuler olarak uygulandi. Onuncu gun ilac uygulamalarindan 45 dk sonra pentilentetrazol (PTZ) 70 mg/kg intraperitoneal olarak enjekte edildi. Hayvanlar 30 dk boyunca gozlemlendi. Racine nobet skalasina gore evreleri belirlendi ve ilk miyoklonik jerk zamani (FMJ) saniye olarak kaydedildi. Islem bitiminden sonra hayvanlarin beyin dokulari alindi. Beyin dokulari rutin histolojik takip sonrasi toluidin blue boyasi ile boyanandi. Hipokampuste CA1 ve dentat girus bolgelerinde noronal hasari gosteren ‘Dark noron’ sayilari yuzde olarak belirlendi. Bulgular: Epileptik davranis sonuclari Racine nobet skalasina (RC) gore degerlendirildiginde, 10 mg/kg tenoksikam kontrole gore nobet evresini anlamli olarak azaltti (p<0,05). Ayrica 10 mg/kg tenoksikam kontrole gore ilk miyoklonik jerk zamanini anlamli olarak arttirdi (p<0,05). Histopatolojik olarak gruplar degerlendirildiginde, CA1 bolgesinde 20 mg/kg tenoksikam kontrole gore noronal hasari arttidigi, buna karsisik dentat girus bolgelesinde 10 mg/kg ve 20 mg/kg tenoksikam noronal hasari anlamli olarak azaltti (p<0,05). Sonuc: Bu calisma tenoksikam uygulamasinin epileptik nobetleri ve nobet sonrasi noron hasarini doz bagimli olarak azaltabilecegini gostermektedir.

Hippocampal infusion of lipopolysaccharide induces immune responses and results in seizures in rats.

Recent studies suggest that epileptic seizures might be facilitated by immune reactions in the brain. However, it remains unclear whether inflammatory reactions could result in acute and chronic epileptic seizures in vivo. In the present study, we investigated whether a hippocampal infusion of lipopolysaccharide (LPS) can induce epileptic seizures in rats. We also aimed to elucidate the molecular mechanisms that underpin this phenomenon. Male Wistar rats received a 1.5 μl infusion of either LPS (5 µg/μl), normal saline, or kainate (KA) (0.4 µg/μl) into the right dorsal hippocampus. No seizures were observed in the normal saline group and associated electroencephalograms showed basic rhythms. Various grades of seizures were observed in rats from the LPS and KA groups, and electroencephalograms were characterized by seizure activities (sharp waves or spikes). In the chronic phase (8 weeks after injection), astrocytes proliferated and the number of neurons decreased in the hippocampus of the rats in the LPS and KA groups. When assessed at the acute phase (within 6 h after injection), the expression of interleukin 1β, tumor necrosis factor α, and neuronal nitric oxide synthase was significantly increased in the hippocampus of the LPS groups. The results of the present study indicate that hippocampal infusion of LPS can activate innate immune responses of glial cells, thereby inducing epileptic seizures and hippocampal sclerosis in rats.

Exploratory behavior alteration as an epileptic comorbidity in elevated plus maze test

Introduction: Epileptic seizure consists of preictal, ictal and postictal period. Postictal period is characterized by a variety of psychiatric phenomenon of which the most frequent ones are anxiety and depressive disorder. Anxiety in rodents can be assessed by measuring the exploratory behavior. Lindane evokes generalized tonic-clonic epileptic seizures in rats, when applied intraperitoneally, due to its lypophilic characteristics. Aim: The aim of this study was to assess exploratory behavior linked with anxiety level in the elevated plus maze test (EPM) upon generalized seizures, induced by lindane in male rats. Material and methods: The experiment was conducted on Wistar albino male rats that were randomly divided into: control group (DMSO, 0.5 ml/kg) and experimental group (lindane, 8 mg/kg) (n=8, each). After the drug injection, the assessment of the seizure intensity lasted for 30 minutes. Descriptive rating scale was used to describe the seizure severity. Subsequently, the EPM testing took place immediately after evoking the seizure (Test 1), after 1h (Test 2) and after 24h (Test 3). Time spent in open areas and number of transitions was further analyzed. Results: Experimental group of animals spent less time in open areas of EPM, when compared to controls in Test 1 and Test 2. The same holds true for the number of transitions to the open area, i.e. lindane-treated animals tend to stay in enclosed parts of the maze in Test1, Test 2. Finally, in Test 3 there was no significant difference between the groups, in any parameter of interest. Conclusion: Lindane-induced generalized epileptic seizures are accompanied by reduced exploratory behavior in the elevated plus maze test, up to 24h after the seizure ended. This finding can be a basis for the further translational research of anxiety as epileptic comorbidity in this experimental model of epilepsy.

Effects of Swimming Exercise on Limbic and Motor Cortex Neurogenesis in the Kainate-Lesion Model of Temporal Lobe Epilepsy.

Temporal lobe epilepsy (TLE) is a common neurological disease and antiseizure medication is often inadequate for preventing apoptotic cell death. Aerobic swimming exercise (EX) augments neurogenesis in rats when initiated immediately in the postictal period. This study tests the hypothesis that aerobic exercise also augments neurogenesis over the long term. Male Wistar rats (age of 4 months) were subjected to chemical lesioning using KA and to an EX intervention consisting of a 30 d period of daily swimming for 15 min, in one experiment immediately after KA lesioning (immediate exposure) and in a second experiment after a 60 d period of normal activity (delayed exposure). Morphometric counting of neuron numbers (NN) and dendritic branch points and intersections (DDBPI) was performed in the CA1, CA3, and dentate regions of hippocampus, in basolateral nucleus of amygdala, and in several areas of motor cortex. EX increased NN and DDBPI in the normal control and the KA-lesioned rats in all four limbic and motor cortex areas studied, after both immediate and 60 d delayed exposures to exercise. These findings suggest that, after temporal lobe epileptic seizures in rats, swimming exercise may improve neural plasticity in areas of the brain involved with emotional regulation and motor coordination, even if the exercise treatment is delayed.

Effects of Swimming Exercise on Learning and Memory in the Kainate-Lesion Model of Temporal Lobe Epilepsy.

An aerobic exercise (Ex) augments neurogenesis and may ameliorate learning and memory deficits in the rat Kainic Acid (KA) model of temporal lobe epilepsy in the short-term but whether it reverses learning and memory deficits after a substantial period of delay remains unclear. This study tests the hypothesis that aerobic Ex attenuates the learning and memory deficits associated with kainate seizures in the long-term. A total of 60 rats were subjected to chemical lesioning using KA and to an Ex intervention consisting of a 30 days period of daily swimming for 15 min, immediately after KA lesioning (immediate exposure) or after a 60 days period of normal activity (delayed exposure). We evaluated spatial learning on a T-maze test, expressed as percentage of correct responses. We evaluated memory on a passive-avoidance test, expressed as time spent in a compartment in which the rats were previously exposed to an aversive stimulus. Ex increases the percentage of correct responses, percentage bias, and number of alternations, associated with the T-maze testing for the normal control, sham-operated control and kainate-lesioned animals after both immediate and delayed exposures to Ex. Ex decreased the time exposed to the aversive stimulus in the smaller compartment of the two-compartment passive-avoidance test, also for the normal control, sham-operated control and kainate-lesioned animals after both immediate and delayed exposures to Ex. These findings suggest that, after temporal lobe epileptic seizures in rats, swimming exercise may attenuate the learning and memory deficits, even if the exercise treatment is delayed.

Study on protective effect of ketogenic diet against hippocampal neurons of kainic acid-induced epileptic rats

Objective To investigate the protective effects of ketogenic diet on hippocampal neurons of kainic acid (KA)-induced epileptic rats. Methods A total of 40 healthy male specific pathogen free (SPF) Sprague-Dawley (SD) rats were randomly divided into 4 groups, with each group containing 10 rats. Epileptic rat models were formed by injection of KA through lateral ventricle with brain stereotactic instrument. According to Racine classification, epileptic seizures in rats above grade Ⅳ were defined successful. Then the rats were given different dietary treatment: Group C with normal saline and normal diet, Group K with normal saline and ketogenic diet, Group E with KA and normal diet, Group EK with KA and ketogenic diet. All rats were observed for 21 d, and were recorded each body weight. The epileptic seizure frequency and duration were observed at 12:00-15:00 daily. At the 21st day, all rats were put to death, and the brain hippocampus tissues were separated. Neuron injury of rat hippocampal CA3 region in Group E and EK was observed by HE staining. Normal neuron number of rat hippocampal CA3 region in Group E and EK was counted by Nissl staining. Results Group C and K had no epileptic seizures, and the neuron number in hippocampal CA3 region was normal. Rats in both Group E and EK had grade Ⅳ or Ⅴ seizures. The number of seizures in Group EK [(17.90 ± 4.12) times] after 21-day ketogenic diet was decreased significantly compared to Group E [(30.50 ± 4.40) times] after 21-day normal diet ( t = 6.606, P = 0.000). The seizure duration in Group EK [(212.70 ± 17.75) s] after 21-day ketogenic diet was shortened compared to Group E [(335.00 ± 14.21) s] after 21-day normal diet ( t = 17.011, P = 0.000). The normal neuron number in hippocampal CA3 region in Group EK (117.67 ± 7.51) was more than those in Group E (71.33 ± 6.11), with statistically significant difference ( t = 9.614, P = 0.000). Conclusions Ketogenic diet has protective effect on hippocampal neurons of kainic acid-induced epileptic rats. DOI: 10.3969/j.issn.1672-6731.2015.11.011

Inhibition of the small GTPase Cdc42 in regulation of epileptic-seizure in rats

Altered expression of neuronal cytoskeletal proteins are known to play an important role in hyper-excitability of neurons in patients and animal models of epilepsy. Our previous work showed that cell division cycle 42 GTP-binding protein (Cdc42), a small GTPase of the Rho-subfamily, is significantly increased in the brain tissue of patients with temporal lobe epilepsy (TLE) and in the brain tissues of the epileptic model of rats. However, whether inhibition of Cdc42 can modify epileptic seizures has not been investigated. In this study, using a pilocarpine-induced epileptic model, we found that pretreatment with ML141, a specific inhibitor of Cdc42, reduces seizure severity. Whole-cell patch-clamp recording on CA1 pyramidal neurons in hippocampal slices from pilocarpine-induced epileptic model demonstrated that ML141 significantly inhibits the frequency of action potentials (APs), increases the amplitude and frequency of miniature inhibitory postsynaptic currents (mIPSCs), and increases the amplitude of evoked inhibitory postsynaptic currents (eIPSCs). However, ML141 did not have an impact on the miniature excitatory postsynaptic currents (mEPSCs). Our results are the first to indicate that Cdc42 plays an important role in the onset and progression of epileptic-seizures by regulating synaptic inhibition.

Altered expression of the voltage-gated calcium channel subunit α2δ-1: A comparison between two experimental models of epilepsy and a sensory nerve ligation model of neuropathic pain

The auxiliary α2δ-1 subunit of voltage-gated calcium channels is up-regulated in dorsal root ganglion neurons following peripheral somatosensory nerve damage, in several animal models of neuropathic pain. The α2δ-1 protein has a mainly presynaptic localization, where it is associated with the calcium channels involved in neurotransmitter release. Relevant to the present study, α2δ-1 has been shown to be the therapeutic target of the gabapentinoid drugs in their alleviation of neuropathic pain. These drugs are also used in the treatment of certain epilepsies. In this study we therefore examined whether the level or distribution of α2δ-1 was altered in the hippocampus following experimental induction of epileptic seizures in rats, using both the kainic acid model of human temporal lobe epilepsy, in which status epilepticus is induced, and the tetanus toxin model in which status epilepticus is not involved. The main finding of this study is that we did not identify somatic overexpression of α2δ-1 in hippocampal neurons in either of the epilepsy models, unlike the upregulation of α2δ-1 that occurs following peripheral nerve damage to both somatosensory and motor neurons. However, we did observe local reorganization of α2δ-1 immunostaining in the hippocampus only in the kainic acid model, where it was associated with areas of neuronal cell loss, as indicated by absence of NeuN immunostaining, dendritic loss, as identified by areas where microtubule-associated protein-2 immunostaining was missing, and reactive gliosis, determined by regions of strong OX42 staining.

A unified approach for detection of induced epileptic seizures in rats using ECoG signals

ObjectiveEpileptic seizure detection is a key step for epilepsy assessment. In this work, using the pentylenetetrazole (PTZ) model, seizures were induced in rats, and ECoG signals in interictal, preictal, ictal, and postictal periods were recorded. The recorded ECoG signals were then analyzed to detect epileptic seizures in the epileptic rats. MethodsTwo different approaches were considered in this work: thresholding and classification. In the thresholding approach, a feature is calculated in consecutive windows, and the resulted index is tracked over time and compared with a threshold. The moment the index crosses the threshold is considered as the moment of seizure onset. In the classification approach, features are extracted from before, during, and after ictal periods and statistically analyzed. Statistical characteristics of some features have a significant difference among these periods, thus resulting in epileptic seizure detection. ResultsSeveral features were examined in the thresholding approach. Nonlinear energy and coastline features were successful in epileptic seizure detection. The best result was achieved by the coastline feature, which led to a mean of a 2-second delay in its correct detections. In the classification approach, the best result was achieved using the fuzzy similarity index that led to Pvalue<0.001. ConclusionThis study showed that variance-based features were more appropriate for tracking abrupt changes in ECoG signals. Therefore, these features perform better in seizure onset estimation, whereas nonlinear features or indices, which are based on dynamical systems, can better track the transition of neural system to ictal period. SignificanceThis paper presents examination of different features and indices for detection of induced epileptic seizures from rat's ECoG signals.

Application of a dissimilarity index of EEG and its sub-bands on prediction of induced epileptic seizures from rat's EEG signals

ObjectiveEpileptic seizures are defined as manifest of excessive and hyper-synchronous activity of neurons in the cerebral cortex that cause frequent malfunction of the human central nervous system. Therefore, finding precursors and predictors of epileptic seizure is of utmost clinical relevance to reduce the epileptic seizure induced nervous system malfunction consequences. Researchers for this purpose may even guide us to a deep understanding of the seizure generating mechanisms. The goal of this paper is to predict epileptic seizures in epileptic rats. MethodsSeizures were induced in rats using pentylenetetrazole (PTZ) model. EEG signals in interictal, preictal, ictal and postictal periods were then recorded and analyzed to predict epileptic seizures. Epileptic seizures were predicted by calculating an index in consecutive windows of EEG signal and comparing the index with a threshold. In this work, a newly proposed dissimilarity index called Bhattacharyya Based Dissimilarity Index (BBDI), dynamical similarity index and fuzzy similarity index were investigated. ResultsBBDI, dynamical similarity index and fuzzy similarity index were examined on case and control groups and compared to each other. The results show that BBDI outperforms dynamical and fuzzy similarity indices. In order to improve the results, EEG sub-bands were also analyzed. The best result achieved when the proposed dissimilarity index was applied on Delta sub-band that predicts epileptic seizures in all rats with a mean of 299.5s. ConclusionThe dissimilarity of neural network activity between reference window and present window of EEG signal has a significant increase prior to an epileptic seizure and the proposed dissimilarity index (BBDI) can reveal this variation to predict epileptic seizures. In addition, analyzing EEG sub-bands results in more accurate information about constituent neuronal activities underlying the EEG since certain changes in EEG signal may be amplified when each sub-band is analyzed separately. SignificanceThis paper presents application of a dissimilarity index (BBDI) on EEG signals and its sub-bands to predict PTZ-induced epileptic seizures in rats. Based on the results of this work, BBDI will predict epileptic seizures more accurately and more reliably compared to current indices that increases epileptic patient comfort and improves patient outcomes.