Antiepileptic effects of ghrelin on pentylenetetrazole-induced seizures in rats

It is well known that neuropeptide Y (NPY) and gamma-aminobutyric acid (GABA) exert antiepileptic effects in animal models. It has recently been shown that ghrelin neurons increase the activities of GABA and NPY in the brain. Therefore it can be said that ghrelin is an antiepileptic agent. In this study we aimed to investigate the antiepileptic effect of ghrelin in an acute experimental epilepsy model in pentylenetetrazole (PTZ) injected rats. Adult male Wistar albino rats were divided into a control group and four experimental groups with seven rats in each group. In order to generate epileptic seizures, PTZ (50mg/kg) was injected intraperitoneally. The experimental groups received intraperitoneal injections of ghrelin at doses of 20, 40, 60 and 80microg/kg 30min before PTZ injection. After PTZ injection, the latencies were separated into three components: first myoclonic jerk, generalized clonic seizures and tonic generalized extension. The injection of 50mg/kg PTZ-induced epileptic seizures in the control group. The onset times of the three characteristic behavioral changes were significantly delayed and the duration of tonic generalized extension was diminished by dose-dependent ghrelin administration. Our results demonstrated that ghrelin suppresses the onset time of PTZ-induced seizures. In the light of our current knowledge, it seems that ghrelin may be considered as an antiepileptic drug.     

Anticonvulsant effects of thymoquinone, the major constituent of Nigella sativa seeds, in mice.

The anticonvulsant effects of thymoquinone, the major constituent of Nigella sativa seeds, were investigated using pentylenetetrazole (PTZ)- and maximal electroshock (MES)-induced seizure models. We also studied the effect of thymoquinone on pentobarbital-induced hypnosis, locomotor activity, and motor coordination. In PTZ-induced seizure, the intraperitoneally injection of thymoquinone with doses of 40 and 80 mg/kg, prolonged the onset of seizures and reduced the duration of myoclonic seizures. The protective effect of thymoquinone against mortality was 71.4% and 100% in the mentioned doses, respectively. In MES model, thymoquinone failed to reduce the duration of seizure, whereas exhibited a complete protection against mortality. In PTZ model, flumazenil (10 mg/kg, i.p.), an antagonist of benzodiazepine (BZD) site in the GABAA-BZD receptor complex, inhibited the prolongation of seizure latency, but did not show any effect on the duration of myoclonic seizures. Also, pretreatment with naloxone (0.1 and 03 mg/kg, i.p.) inhibited the prolongation of myoclonic seizure latency and antagonized the reduction of myoclonic seizure duration induced by thymoquinone (40 and 80 mg/kg) in the PTZ model. Moreover, thymoquinone (40 and 80 mg/kg) did not have any hypnosis effect in the pentobarbital-induced hypnosis, but impaired the motor coordination and reduced the locomotor activity. These results indicate that thymoquinone may have anticonvulsant activity in the petit mal epilepsy probably through an opioid receptor-mediated increase in GABAergic tone.     

Protective effects of long-term probiotic mixture supplementation against pentylenetetrazole-induced seizures,inflammation and oxidative stress in rats

Emerging evidence indicates that dysbiosis of gut microbiota plays an important role in epilepsy, although the underlying mechanisms remain unclear due to the complex nature of both microbial composition and pathophysiology of epilepsy. We investigated effects of long-term probiotics supplementation on epileptic seizures, and inflammatory and oxidant/antioxidant biomarkers in a pentylenetetrazole(PTZ)-induced seizure model in rats.Male Wistar weaner-rats were divided into four groups. The first two groups received 1 ml/day saline solution, while the other groups received 0.05 mg/1ml/day vehicle or 109cfu/1ml/day probiotic-mixture, respectively, for 60 days by gavage. Seizure was induced by a single convulsive dose of PTZ. Seizures were evaluated using Racine's scale. Concentrations of pro-inflammatory cytokines in plasma and brain tissue were determined using ELISA, while oxidant/antioxidant biomarkers were measured using an automated-colorimetric method.Probiotics supplementation exhibited anticonvulsant effects against PTZ-induced seizures by retarding onset-times of both myoclonic-jerk and generalized tonic–clonic seizure, and by shortening duration of generalized tonic–clonic seizure. Additionally, it alleviated PTZ-induced increases in levels of pro-inflammatory cytokines IL-1β, IL-6, and IL-17A, but not of IFNγ, in plasma and brain tissue. Moreover, it restored PTZinduced fluctuations in levels of oxidants TOS and disulfide, and of antioxidants native thiol and total thiol.Our findings suggest that long-term probiotics supplementation exhibits protective effects against epileptic seizures, and alleviates (neuro)inflammation and oxidative stress related to pathophysiology of epilepsy. A probiotic-rich diet provided from childhood may provide prophylaxis against epileptic seizures, especially in susceptible individuals, as the neonate diet represents a fundamental extrinsic factor in establishing gut microbiota.     

The Search for New Screening Models of Pharmacoresistant Epilepsy: Is Induction of Acute Seizures in Epileptic Rodents a Suitable Approach?

Epilepsy, a prevalent neurological disease characterized by spontaneous recurrent seizures (SRS), is often refractory to treatment with anti-seizure drugs (ASDs), so that more effective ASDs are urgently needed. For this purpose, it would be important to develop, validate, and implement new animal models of pharmacoresistant epilepsy into drug discovery. Several chronic animal models with difficult-to-treat SRS do exist; however, most of these models are not suited for drug screening, because drug testing on SRS necessitates laborious video-EEG seizure monitoring. More recently, it was proposed that, instead of monitoring SRS, chemical or electrical induction of acute seizures in epileptic rodents may be used as a surrogate for testing the efficacy of novel ASDs against refractory SRS. Indeed, several ASDs were shown to lose their efficacy on acute seizures, when such seizures were induced by pentylenetetrazole (PTZ) in epileptic rather than nonepileptic rats, whereas this was not observed when using the maximal electroshock seizure test. Subsequent studies confirmed the loss of anti-seizure efficacy of valproate against PTZ-induced seizures in epileptic mice, but several other ASDs were more potent against PTZ in epileptic than nonepileptic mice. This was also observed when using the 6-Hz model of partial seizures in epileptic mice, in which the potency of levetiracetam, in particular, was markedly increased compared to nonepileptic animals. Overall, these observations suggest that performing acute seizure tests in epileptic rodents provides valuable information on the pharmacological profile of ASDs, in particular those with mechanisms inherent to disease-induced brain alterations. However, it appears that further work is needed to define optimal approaches for acute seizure induction and generation of epileptic/drug refractory animals that would permit reliable screening of new ASDs with improved potential to provide seizure control in patients with pharmacoresistant epilepsy.     

Inhibition of Death-associated Protein Kinase 1 protects against Epileptic Seizures in mice

Epilepsy is a chronic encephalopathy and one of the most common neurological disorders. Death-associated protein kinase 1 (DAPK1) expression has been shown to be upregulated in the brains of human epilepsy patients compared with those of normal subjects. However, little is known about the impact of DAPK1 on epileptic seizure conditions. In this study, we aim to clarify whether and how DAPK1 is regulated in epilepsy and whether targeting DAPK1 expression or activity has a protective effect against epilepsy using seizure animal models. Here, we found that cortical and hippocampal DAPK1 activity but not DAPK1 expression was increased immediately after convulsive pentylenetetrazol (PTZ) exposure in mice. However, DAPK1 overexpression was found after chronic low-dose PTZ insults during the kindling paradigm. The suppression of DAPK1 expression by genetic knockout significantly reduced PTZ-induced seizure phenotypes and the development of kindled seizures. Moreover, pharmacological inhibition of DAPK1 activity exerted rapid antiepileptic effects in both acute and chronic epilepsy mouse models. Mechanistically, PTZ stimulated the phosphorylation of NR2B through DAPK1 activation. Combined together, these results suggest that DAPK1 regulation is a novel mechanism for the control of both acute and chronic epilepsy and provide new therapeutic strategies for the treatment of human epilepsy.     

Seizures Induced by Pentylenetetrazole in the Adult Zebrafish: A Detailed Behavioral Characterization

Pentylenetetrazole (PTZ) is a common convulsant agent used in animal models to investigate the mechanisms of seizures. Although adult zebrafish have been recently used to study epileptic seizures, a thorough characterization of the PTZ-induced seizures in this animal model is missing. The goal of this study was to perform a detailed temporal behavior profile characterization of PTZ-induced seizure in adult zebrafish. The behavioral profile during 20 min of PTZ immersion (5, 7.5, 10, and 15 mM) was characterized by stages defined as scores: (0) short swim, (1) increased swimming activity and high frequency of opercular movement, (2) erratic movements, (3) circular movements, (4) clonic seizure-like behavior, (5) fall to the bottom of the tank and tonic seizure-like behavior, (6) death. Animals exposed to distinct PTZ concentrations presented different seizure profiles, intensities and latencies to reach all scores. Only animals immersed into 15 mM PTZ showed an increased time to return to the normal behavior (score 0), after exposure. Total mortality rate at 10 and 15 mM were 33% and 50%, respectively. Considering all behavioral parameters, 5, 7.5, 10, and 15 mM PTZ, induced seizures with low, intermediate, and high severity, respectively. Pretreatment with diazepam (DZP) significantly attenuated seizure severity. Finally, the brain PTZ levels in adult zebrafish immersed into the chemoconvulsant solution at 5 and 10 mM were comparable to those described for the rodent model, with a peak after a 20-min of exposure. The PTZ brain levels observed after 2.5-min PTZ exposure and after 60-min removal from exposure were similar. Altogether, our results showed a detailed temporal behavioral characterization of a PTZ epileptic seizure model in adult zebrafish. These behavioral analyses and the simple method for PTZ quantification could be considered as important tools for future investigations and translational research.     

Evaluation of sphingolipids changes in brain tissues of rats with pentylenetetrazol-induced kindled seizures using MALDI-TOF-MS

Abnormal lipid metabolism has been implicated in the pathogenesis of many neural system diseases, including epilepsy. Pentylenetetrazol (PTZ)-induced kindling in rodents is considered a model of human absence epilepsy and myoclonic, generalized tonic-clonic seizure. In an effort to further understand the mechanism for PTZ-induced seizure, we analyzed crude lipids and sphingolipids in the cortex, hippocampus, and brain stem of normal and PTZ-rats using delayed extraction matrix-assisted laser desorption ionization time-of-flight mass spectrometry (DE MALDI-TOF-MS). It was found that phosphatidylcholines dominated the crude lipids in different tissues and there were no obvious differences in crude lipid profiles of different tissues between normal and PTZ-rats. However, ceramide, sphingomyelins, and ceramide-monohexoside were differently distributed in normal and PTZ-rats. Using the reference mass spectra method established in our laboratory, it was shown that sphingomyelins and ceramide-monohexoside levels were elevated in the brain tissues of PTZ-rats. Ceramide levels were found to be higher in brain stem than in cortex and hippocampus of normal rats, and PTZ caused a general decrease in ceramide levels. These data suggest that changes in sphingolipid metabolism contribute to PTZ-induced seizure.     

Gastrodin Suppresses Pentylenetetrazole-Induced Seizures Progression by Modulating Oxidative Stress in Zebrafish

Pentylenetetrazole (PTZ)-induced seizures in Zebrafish models are now widely accepted for investigating human disease epilepsy. In epilepsy, the generation of oxidative stress contributes to the brain injury. Although Gastrodin (GAS) has been reported to have anticonvulsant activities, its effects on zebrafish seizure models and the underlying mechanism remain unclear. In this study, we evaluated the effects of GAS pretreatment on PTZ-induced seizures in zebrafish larvae and investigated the underlying mechanism related to its anti-oxidative defense. We found for the first time that GAS significantly decreased seizure-like behavior and extended the latency period to the onset of seizures. In addition, after exposure to GAS, anti-oxidative activity was observed in PTZ-induced seizures by measurement of antioxidant enzymes activities and oxidative stress-related genes expression. The overall results indicate that GAS attenuates PTZ-induced seizures in a concentration-dependent manner and modulates oxidative stress to potentially protect larval zebrafish from further seizures. Furthermore, our results have provided novel insights into GAS related therapy of seizures and associated neurological disorders.     

Suppression of generalized seizures activity by intrathalamic 2-chloroadenosine application

In the present study, we investigated the effects of micro-injecting 2-chloroadenosine (2-CADO; an adenosine receptor agonist) into the thalamus alone and with theophylline (a nonspecific adenosine receptor antagonist) pretreatment on pentylenetetrazol (PTZ)-induced tonic-clonic seizures in male Wistar albino rats. Following intrathalamic 2-CADO injection alone or theophylline pretreatment, 50 mg kg(-1) PTZ was given ip after 1 and 24 hrs. The duration of epileptic seizure activity was recorded by cortical electroencephalogram (EEG), and seizure severity was behaviorally scored. Intrathalamic 2-CADO administration induced significant decreases in both seizure duration and seizure severity scores at 1 and 24 hrs, but the effects were more abundant on the seizures induced after 24 hrs. On the other hand, pretreatment with theophylline prevented the inhibitor effect of 2-CADO on seizure activity and increased both seizure duration and seizure scores. Present results suggest that the activation of adenosine receptors in the thalamus may represent another anticonvulsant/modulatory site of adenosine action during the course of the PTZ-induced generalized tonic-clonic seizures and provide additional data for the involvement of the adenosinergic system in the generalized seizures model.     

Effects of lipopolysaccharide on blood-brain barrier permeability during pentylenetetrazole-induced epileptic seizures in rats

We investigated the effects of lipopolysachharide (LPS) on functional and structural properties of the blood-brain barrier (BBB) during pentylenetetrazole (PTZ)-induced epileptic seizures in rats. Arterial blood pressure was significantly elevated during epileptic seizures irrespective of LPS pretreatment. Plasma levels of interleukin (IL)-1, interleukin (IL)-6, nitric oxide (NO) and malondialdehyde (MDA) increased while catalase concentrations decreased in animals treated with LPS, PTZ and LPS plus PTZ. The significantly increased BBB permeability to Evans blue (EB) dye in the cerebral cortex, diencephalon and cerebellum regions of rats by PTZ-induced seizures was markedly reduced upon LPS pretreatment. Immunoreactivity for tight junction proteins, zonula occludens-1 and occludin, did not change in brain vessels of animals treated with PTZ and LPS plus PTZ. Glial fibrillary acidic protein immunoreactivity was increased in LPS, but not in PTZ and LPS plus PTZ. These results indicate that LPS pretreatment reduces the passage of EB dye bound to albumin into the brain, at least partly, by increasing plasma NO and IL-6 levels during PTZ-induced epileptic seizures. We suggest that LPS may provide protective effects on the BBB integrity during epileptic seizures through transcellular pathway, since the paracellular route remained unaffected by LPS and LPS plus PTZ.     

Dose-finding study with nicotine as a proconvulsant agent in PTZ-induced seizure model in mice

The present study was conducted to investigate the possible interaction between low doses of nicotine and pentylenetetrazole (PTZ) in vivo and also to evaluate the influence of nicotine on the antiseizure efficacy of topiramate and sodium valproate in the PTZ-induced seizure model in mice. Graded dose–response study with nicotine showed the CD50 value for nicotine at 6.76 mg/kg. i.p. Subtheshold dose of nicotine (4 mg/kg, i.p.) pretreatment significantly decreased the CD50 value for PTZ from 47.86 mg/kg, i.p. (of PTZ per se) to 31.62 mg/kg, i.p. Sodium valproate but not topiramate, significantly inhibited PTZ-induced seizures in mice with an ED50 value of 177.83 mg/kg, i.p. Nonconvulsive dose of nicotine (1 mg/kg, i.p.) significantly antagonized the protective efficacy of sodium valproate against PTZ-induced seizures and increased the ED50 value to 338.84 mg/kg, i.p. PTZ-induced seizures significantly increased the mouse brain levels of MDA and reduced the level of GSH while sodium valproate reversed such changes. Nicotine pretreatment reversed the anti-lipid peroxidative action of sodium valproate in the PTZ-induced seizure model in mice. The study highlighted the convulsant as well as proconvulsant role of nicotine and established dose discrimination for nicotine as a proconvulsant agent and an anti-antiseizure agent. The study bears significant clinical relevance particularly amongst epileptic smokers who may show failure of efficacy of antiepileptic agents and present with breakthrough seizure attacks on exposure to nicotine.     

Transient Morphological Alterations in the Hippocampus After Pentylenetetrazole-Induced Seizures in Rats

The relationships between seizures, neuronal death, and epilepsy remain one of the most disputed questions in translational neuroscience. Although it is broadly accepted that prolonged and repeated seizures cause neuronal death and epileptogenesis, whether brief seizures can produce a mild but similar effect is controversial. In the present work, using a rat pentylenetetrazole (PTZ) model of seizures, we evaluated how a single episode of clonic–tonic seizures affected the viability of neurons in the hippocampus, the area of the brain most vulnerable to seizures, and morphological changes in the hippocampus up to 1 week after PTZ treatment (recovery period). The main findings of the study were: (1) PTZ-induced seizures caused the transient appearance of massively shrunken, hyperbasophilic, and hyperelectrondense (dark) cells but did not lead to detectable neuronal cell loss. These dark neurons were alive, suggesting that they could cope with seizure-related dysfunction. (2) Neuronal and biochemical alterations following seizures were observed for at least 1 week. The temporal dynamics of the appearance and disappearance of dark neurons differed in different zones of the hippocampus. (3) The numbers of cells with structural and functional abnormalities in the hippocampus after PTZ-induced seizures decreased in the following order: CA1?>?CA3b,c?>?hilus?>?dentate gyrus. Neurons in the CA3a subarea were most resistant to PTZ-induced seizures. These results suggest that even a single seizure episode is a potent stressor of hippocampal neurons and that it can trigger complex neuroplastic changes in the hippocampus.     

Mouse models of Down syndrome: gene content and consequences

Down syndrome (DS), trisomy of human chromosome 21 (Hsa21), is challenging to model in mice. Not only is it a contiguous gene syndrome spanning 35 Mb of the long arm of Hsa21, but orthologs of Hsa21 genes map to segments of three mouse chromosomes, Mmu16, Mmu17, and Mmu10. The Ts65Dn was the first viable segmental trisomy mouse model for DS; it is a partial trisomy currently popular in preclinical evaluations of drugs for cognition in DS. Limitations of the Ts65Dn are as follows: (i) it is trisomic for 125 human protein-coding orthologs, but only 90 of these are Hsa21 orthologs and (ii) it lacks trisomy for ~75 Hsa21 orthologs. In recent years, several additional mouse models of DS have been generated, each trisomic for a different subset of Hsa21 genes or their orthologs. To best exploit these models and interpret the results obtained with them, prior to proposing clinical trials, an understanding of their trisomic gene content, relative to full trisomy 21, is necessary. Here we first review the functional information on Hsa21 protein-coding genes and the more recent annotation of a large number of functional RNA genes. We then discuss the conservation and genomic distribution of Hsa21 orthologs in the mouse genome and the distribution of mouse-specific genes. Lastly, we consider the strengths and weaknesses of mouse models of DS based on the number and nature of the Hsa21 orthologs that are, and are not, trisomic in each, and discuss their validity for use in preclinical evaluations of drug responses.     

Influence of sex on the interaction between dizocilpine (MK-801) pretreatment and acute cold-restraint stress in epilepsy susceptibility in an animal study

Background: Stress is a part of our daily life, inducing neurochemical and neurophysiological changes in the central nervous system.Objective: The present study was designed to investigate the importance of sex differences in the interaction between dizocilpine (MK-801) pretreatment and acute cold-restraint stress (CRS) in pentylenetetrazole (PTZ)-induced seizures in Swiss albino mice.Methods: A CRS protocol was applied to mice to investigate the interaction between MK-801 pretreatment (30 min before CRS) and stress (followed by PTZ injection) in epilepsy susceptibility. For this purpose, 6 groups were designated: (1) PTZ control group (received only PTZ); (2) stress group (received stress and PTZ); (3) saline group (received saline and PTZ); (4) MK-801 group (received MK-801 and PTZ); (5) saline + stress group (received saline, stress, and PTZ); and (6) MK-801 + stress group (received MK-801, stress, and PTZ).Results: Pretreatment with MK-801 (0.125, 0.25, 0.50 mg/kg) significantly potentiated the protective effect of stress in PTZ-induced (65 mg/kg) seizures in both sexes by prolonging the onset of myoclonic jerks and clonic convulsions. Male mice had a significantly greater delay in the onset of myoclonic jerks (males, 66.7–295.5 sec; females, 54.0–247.5 sec; P < 0.05) and clonic convulsions (males, 123.5–789.8 sec; females, 94.5–757.2 sec; P < 0.05) compared with female mice in all groups (ie, PTZ control, stress, saline, MK-801, saline + stress, and MK-801 + stress groups).Conclusion: The findings of this study in mice suggest the involvement of sex hormones in the interaction between MK-801 pretreatment and acute CRS in PTZ-induced seizures.     

Sex differences in modulating blood brain barrier permeability by NO in pentylenetetrazol-induced epileptic seizures

Susceptibility to epilepsy as well as BBB dysfunction in some pathological conditions varies depending on sex difference. It has recently been shown that systemically given NO donor and antagonists modify the nature of seizures induced by PTZ (pentylenetetrazol) differently in male and female rats. This study investigates the role of NO on BBB permeability in PTZ seizures with sex differences using NO donor, sodium nitroprusside (SNP), and NOS inhibitor, NG-nitro-L-arginine methyl ester (L-NAME). Nitrite+nitrate levels as indices of NO generation in the brain were also assessed. L-NAME prolonged seizure latency in male rats, seizure intensity and seizure duration were lessened. L-NAME depicted opposite effects in seizure nature in female rats. SNP prolonged seizure latency, while seizure intensity and duration were lessened only in female rats. L-NAME in male rats increased L-NAME use in female rats (not in male rats) which resulted in a more leaky BBB especially in midbrain, thalamus, hippocampus, corpus striatum and cerebellum whereas SNP use in male rats and not in female rats resulted in pronounced BBB opening in all brain regions studied than PTZ per se. L-NAME while decreasing nitrite+nitrate levels in male rat brains, acted in an opposite fashion in females. SNP use depicted an inverse picture with respect to L-NAME, with an opposite action in different sexes. This study reveals that NO effect on BBB in PTZ-induced seizures depends unequivocally on sex difference. The sex-dependent action of NO in seizures and in CNS pathologies warrants further investigation.     

Involvement of nitric oxide in pentylenetetrazole-induced kindling in rats

We investigated the role of nitric oxide (NO) and brain-derived neurotrophic factor (BDNF) in the pentylenetetrazole (PTZ)-induced kindling in rats. Seizures were induced by single administration of PTZ, which was associated with an increase in levels of NO metabolites (NOx) in the hippocampus. Pretreatment with a neuronal NO synthase inhibitor, 7-nitroindazole (7-NI), diminished the PTZ-induced increase in NOx levels without affecting the seizure intensity. Repeated administration of PTZ produced a gradual increase in the seizure intensity, leading to the development of kindling. In the kindled rats, PTZ at a dose of 40 mg/kg increased NOx levels in the hippocampus, whereas it had no effect in control animals. Cotreatment of 7-NI with PTZ blocked the development of kindling and attenuated the PTZ-induced increase in NOx levels. A significant increase in BDNF levels was observed in the hippocampus of the kindled rats, which returned to the control levels following seizures induced by PTZ. 7-NI reduced the hippocampal BDNF levels in control rats and suppressed the increase of BDNF levels in the kindled rats. Our findings suggest that NO plays a role in the development of PTZ-induced kindling and that BDNF may contribute to the NO-dependent plastic changes in neuronal excitability.     

Pentylenetetrazol (PTZ)-kindling development in intact and subcortical structure lesioned rats

Kindling was induced in male wistar rats (280-320 g) by daily ip injections of PTZ in subthreshold doses (30 mg/kg). Repeated administration of PTZ to animals resulted in developing of enhanced seizures and also enhanced seizure susceptibility which could be sustained for a long time (6 months) after last seizure paroxysm. The lesioned hippocampus retarded the manifestation of PTZ kindling, where as lesioned caudate nuclei increased the seizure kindling development. Results also revealed hippocampus as a determinant structure in PTZ kindling formation, which stabilize the epileptic manifestations and make them chronic, at the same time caudate nuclei retarded the epileptic seizures stabilization. This role may be only antiepileptic, and not anti-kindling as is known for caudate nuclei.     

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 299.5 s.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.     

Sodium Valproate Reduces Neuronal Apoptosis in Acute Pentylenetetrzole-Induced Seizures via Inhibiting ER Stress

Endoplasmic reticulum (ER) stress has been indicated to be involved in the pathogenesis of epilepsy. Sodium valproate (VPA), one of the most commonly used antiepileptic drugs, is reported to regulate ER stress in many neurological diseases. However, the effect of VPA on ER stress in epilepsy remains unclear. The current study was performed to investigate the role of ER stress in the neuroprotection of VPA against seizure induced by pentylenetetrzole (PTZ). Our results showed that VPA treatment could inhibit the increased expressions of ER stress proteins (GRP78 and CHOP), and significantly reduce neuronal apoptosis in the PTZ-induced experimental seizure model. In addition, Salubrinal, an ER stress inhibitor, was used as a positive control, and exhibited neuroprotective effects via inhibiting excessive ER stress in the seizure model, which further supported that the inhibition in ER stress by VPA treatment could exert neuroprotection in seizures. In summary, our work demonstrated for the first time that ER stress was involved in the neuroprotective potential of VPA for seizures.

     

Neurohypophyseal hormones protect against pentylenetetrazole-induced seizures in zebrafish: Role of oxytocin-like and V1a-like receptor

Oxytocin (OT) and arginine-vasopressin (AVP) are involved in the physiological response to different stressors like the occurrence of seizures which is regarded as a severe stress factor. Zebrafish (Danio rerio) is recently featured as a model of epilepsy but the role of neurohypophyseal hormones on this teleost is still unknown. We attempted to determine whether non-mammalian homologues like isotocin (IT) and vasotocin (AVT) affected pentylenetetrazole (PTZ)-induced seizures in adult zebrafish in comparison with OT/AVP. The mechanism was studied using the most selective OT and AVP receptor antagonists. Zebrafish were injected i.m. with increasing doses (0.1-40ng/kg) of the neuropeptides 10min before PTZ exposure. DesGly-NH2-d(CH2)5-[D-Tyr2,Thr4]OVT (desglyDTyrOVT) for OT receptor and SR49059 for V1a subtype receptor, were injected together with each agonist 20min before PTZ exposure. All the peptides significantly decreased the number of seizures, increased the mean latency time to the first seizure and decreased lethality. This protective effect led to a dose-response curve following a U-shaped form. IT was approximately 40 times more active than OT while AVT was 20 times more potent than AVP in reducing the number of seizures. DesglyDTyrOVT was more effective in antagonizing OT/IT, while SR49059 mainly blocked AVP/AVT-induced protection against PTZ-induced seizures. The present findings provide direct evidence of an important involvement of IT/OT and AVP/AVT as anticonvulsant agents against PTZ-induced seizures with a receptor-mediated mechanism in zebrafish. These data reinforce zebrafish as an emerging experimental model to study and identify new antiepileptic drugs.