PTZ Administration Research Articles

Aquaporin-4 inhibition attenuates Pentylenetetrazole-induced behavioral seizures and cognitive impairments in kindled rats

Epilepsy is a neurological condition distinguished by recurrent and unexpected seizures. Astrocytic channels and transporters are essential for maintaining normal neuronal functionality. The astrocytic water channel, aquaporin-4 (AQP4), which plays a pivotal role in regulating water homeostasis, is a potential target for epileptogenesis. In present study, we examined the effect of different doses (10, 50, 100 μM and 5 mM) of AQP4 inhibitor, 2-nicotinamide-1, 3, 4-thiadiazole (TGN-020), during kindling acquisition, on seizure parameters and seizure-induced cognitive impairments. Animals were kindled by injection of pentylenetetrazole (PTZ: 37.5 mg/kg, i.p.). TGN-020 was administered into the right lateral cerebral ventricle 30 min before PTZ every alternate day. Seizure parameters were assessed 20 min after PTZ administration. One day following the last PTZ injection, memory performance was investigated using spontaneous alternation in Y-maze and novel object recognition (NOR) tests. The inhibition of AQP4 during the kindling process significantly decreased the maximal seizure stage and seizure duration (two-way ANOVA, P = 0.0001) and increased the latency of seizure onset and the number of PTZ injections required to induce different seizure stages (one-way ANOVA, P = 0.0001). Compared to kindled rats, the results of the NOR tests showed that AQP4 inhibition during PTZ-kindling prevented recognition memory impairment. Based on these results, AQP4 could be involved in seizure development and seizure-induced cognitive impairment. More investigation is required to fully understand the complex interactions between seizure activity, water homeostasis, and cognitive dysfunction, which may help identify potential therapeutic targets for these conditions.

Antiseizure Effects of Peganum harmala L. and Lavandula angustifolia

Peganum harmala L. and Lavandula angustifolia are two traditional herbs with probable antiseizure effects. This study evaluated the effects of these two herbal extracts on pentylenetetrazol‐ (PTZ‐) induced seizures in mice. We prepared hydroalcoholic extracts using P. harmala seeds and the aerial parts of L. angustifolia and then randomly divided 190 mice into 19 groups. Normal saline (10 mg/kg), diazepam (2 mg/kg), P. harmala (2.5, 5, 10, 15, 30, 45, and 60 mg/kg), and L. angustifolia (200, 400, 600, and 800 mg/kg) were intraperitoneally (IP) administrated 30 min before an IP administration of PTZ (90 mg/kg). Animals were observed for behavioral changes for one hour. In addition, the effects of flumazenil and naloxone on the antiseizure activity of P. harmala and L. angustifolia were assessed. P. harmala showed antiseizure activity at the dose of 10 mg/kg; it prolonged the seizure latency and decreased the seizure duration. The mortality protection rate was 90% for this herbal extract. L. angustifolia (600 mg/kg) prolonged the seizure latency and decreased both seizure duration and mortality. Neither flumazenil nor naloxone significantly reversed the antiseizure activities of P. harmala and L. angustifolia. In mice, the hydroalcoholic extracts of P. harmala and L. angustifolia showed antiseizure activity against PTZ‐induced seizures. We could not delineate the exact antiseizure mechanisms of these extracts in the current study.

Evaluation of 5-[(Z)-(4-nitrobenzylidene)]-2-(thiazol-2-ylimino)-4-thiazolidinone (Les-6222) as Potential Anticonvulsant Agent

It was determined that the studied 5-[(Z)-(4-nitrobenzylidene)]-2-(thiazol-2-ylimino)-4-thiazolidinone (Les-6222) affects the cyclooxygenase pathway of the arachidonic acid cascade, the markers of damage to neurons on models of PTZ kindling. In the model of chronic epileptogenesis in mice (pentylenetetrazole kindling), a 4-thiazolidinone derivative showed high anticonvulsant activity, which is weaker than the effect of sodium valproate and higher than Celecoxib. The mentioned compound has a pronounced anti-inflammatory effect in the brain on the background of the PTZ kindling, reliably inhibiting COX-1 and COX-2. The predominant inhibition of COX-2 by 44.5% indicates this enzyme’s high selectivity of Les-6222. According to the molecular docking study results, the studied compound revealed the properties of COX-1/COX-2 inhibitor and especially 5-LOX/FLAP. The decreasing content of 8-isoprostane in the brain of mice of the Les-6222 group indicates a beneficial effect on cell membranes in the background of oxidative stress during the long-term administration of PTZ. In addition, Les-6222 significantly decreased the content of neuron-specific enolase, indicating neuroprotective properties in the background of chronic epileptogenesis. The obtained results experimentally substantiate the feasibility of further developing Les-6222 as a promising anticonvulsant agent.

Genetic Knockout of TRPM2 Increases Neuronal Excitability of Hippocampal Neurons by Inhibiting Kv7 Channel in Epilepsy.

Epilepsy is a chronic brain disease that makes serious cognitive and motor retardation. Ion channels affect the occurrence of epilepsy in various ways, but the mechanisms have not yet been fully elucidated. Transient receptor potential melastain2 (TRPM2) ion channel is a non-selective cationic channel that can permeate Ca2+ and critical for epilepsy. Here, TRPM2 gene knockout mice were used to generate a chronic kindling epilepsy model by PTZ administration in mice. We found that TRPM2 knockout mice were more susceptible to epilepsy than WT mice. Furthermore, the neuronal excitability in the hippocampal CA1 region of TRPM2 knockout mice was significantly increased. Compared with WT group, there were no significant differences in the input resistance and after hyperpolarization of CA1 neurons in TRPM2 knockout mice. Firing adaptation rate of hippocampal CA1 pyramidal neurons of TRPM2 knockout mice was lower than that of WT mice. We also found that activation of Kv7 channel by retigabine reduced the firing frequency of action potential in the hippocampal pyramidal neurons of TRPM2 knockout mice. However, inhibiting Kv7 channel increased the firing frequency of action potential in hippocampal pyramidal neurons of WT mice. The data suggest that activation of Kv7 channel can effectively reduce epileptic seizures in TRPM2 knockout mice. We conclude that genetic knockout of TRPM2 in hippocampal CA1 pyramidal neurons may increase neuronal excitability by inhibiting Kv7 channel, affecting the susceptibility to epilepsy. These findings may provide a potential therapeutic target for epilepsy.

The Role of the NMDA Receptor in the Anticonvulsant Effect of Ellagic Acid in Pentylenetetrazole-Induced Seizures in Male Mice.

Methods In this experimental study, 64 mice were divided into 8 groups and received the following: normal saline; EA at doses of 6.25, 12.5, and 25 mg/kg; NMDA agonist at a dose of 75 mg/kg; NMDA antagonist (ketamine) at a dose of 0.5 mg/kg; an effective dose of EA plus NMDA agonist; and a subeffective dose of EA plus ketamine. We induced seizure using intravenous administration of PTZ. 60 minutes before induction of seizure, drugs were administrated. Duration lasts to seizure-induced was measured. Finally, the gene expression of NMDA receptor subunits (Nr2a and Nr2b) was assessed in the prefrontal cortex. Results Results showed that EA increased the seizure threshold and decreased the expression of Nr2a and Nr2b. We determined that ketamine potentiated and NMDA attenuated the effects of subeffective and effective doses of EA. Conclusion EA probably via attenuation of the NMDA-R pathway possesses an anticonvulsant effect in PTZ-induced seizure in mice.

Effects of Stevia rebaudiana Bertoni extracts in the rat model of epilepsy induced by pentylenetetrazol: Sirt-1, at the crossroads between inflammation and apoptosis.

The current study investigated the effects of stevia extracts on a PTZ-induced epileptic rat model and its potential mechanism. Thirty male Sprague-Dawley rats were equally subdivided into 3 groups; (1) normal control (NC) group, (2) PTZ-group: received PTZ (50 mg/kg, i.p. every other day) for 2 weeks, and (3) PTZ+ Stevia group: received PTZ and stevia (200 mg/kg orally daily) for 4 weeks (2 weeks before the start of PTZ treatment and 2 weeks with PTZ administration). The first jerk latency and the seizure score were assessed in rats. Also, brain tissue samples were collected by the end of the experiment, and oxidative stress markers (catalase, MDA, and total antioxidant capacity (TAC)) were measured by biochemical analysis in hippocampal brain homogenates. Also, in the hippocampus, the expression of IL6 and Bcl-2 at the mRNA level and expression of Sirt-1, P53, caspase-3, GFAP, and NF-kB in CA3 hippocampal region by immunohistochemistry was investigated. PTZ substantially increased the seizure score and decreased the seizure latency. Also, PTZ significantly increased MDA, GFAP, IL-6, NF-kB, caspase-3, and p53 and significantly reduced Sirt-1, TAC, and Bcl-2 in hippocampal tissues compared to the control group (p < 0.01). However, Stevia Rebaudiana Bertoni (Stevia R.) significantly attenuated the PTZ-induced seizures, improved oxidative stress markers, downregulated GFAP, IL-6, NF-kB, caspase-3, and p53, and upregulated Sirt-1 and Bcl-2 in the CA3 hippocampal region (p < 0.01). In conclusion, Stevia R. exhibits neuroprotective and antiepileptic actions in PTZ-induced epilepsy due to its antioxidant, anti-apoptotic, and anti-inflammatory effects. Additionally, the Sirt-1 pathway might be involved in the antiepileptic and neuroprotective effects of stevia in PTZ-kindled epileptic rat model.

A Nigerian‐Made Modified Atkins Diet: Hope for Patients with Intractable Epilepsy

Introduction : Modified Atkins diet (MAD), a variant of ketogenic diet (KD) has been reported in many studies to have equal potency to the classical KD. The unpalatable taste of the classical KD has led to its unpopular use, making it necessary to use it variants. This work involved investigating the anti-epileptic and nootropic effect of a Nigerian-made Modified Atkins Diet that failed in some acute seizure tests in mice. Research Hypothesis : It was hypothesized that the formulated MAD will produce significant anti-convulsant activity in mice. Methods Ethical Approval: Ethical approval for the study was obtained from the ABU Committee on Animal Use and Care. Dietary Pre-treatment: The mice, at P28 were given appropriate diet (Normal Laboratory diet or MAD) for thirty (30) days. Twenty-one (21) litters were weaned at P28 onto modified Atkins diet for 4 weeks. Other litters were fed normal laboratory diet and started on MAD at P56 (8 weeks) for 30 days. PTZ-Induced Kindling: Protocol described by Shimada and Yamagata (2018) was adopted. Each mouse was observed for 30 minutes after every PTZ administration and the seizure behavior was scored as follows; 0: normal behavior, no abnormality; 1: immobilization, lying on belly; 2: head nodding, facial, forelimb, or hindlimb myoclonus; 3: continuous whole-body myoclonus, myoclonic jerks, tail held up stiffly; 4: rearing, tonic seizure, falling down on its side; 5: tonic-clonic seizure, falling down on its back, wild rushing and jumping; 6: death. Morris Water Maze: The effect of the diet on learning and reference memory was investigated using the Protocol described by Zhao et al. (2004) with adopted with slight modifications: 4 daily trials instead of 6 daily trials were done, non-toxic blue dye was used in place of non-fatty milk to make the pool opaque. Statistical analysis: Data were analyzed aligned-rank test followed by Mann-U Whitney correction, Kruskal-Wallis test and Kaplan Meier survival analysis where appropriate. Results As shown in the fig.1a, MAD statistically significantly increased seizure threshold in the first half of epilepsy induction before the mice in the two diet eventually became refractory to the effect of PTZ at sub-convulsive doses. Kaplan Meier survival analysis revealed the ability of Modified Atkins Diet to decrease seizure susceptibility as shown in fig.1b; Mice treated with MAD had a tonic-clonic seizure survival probability of approximately 60% while mice on LD has a probability of just 20% at the end of the injection period. Modified Atkins diet did not negatively impair learning and memory. As shown in fig. 2a, it significantly increased escape latency of the mice over time when compared to the laboratory diet group in which the escape time was not different in all test days. There however, was no significant difference (p<0.05) in the time spent in all quadrants in both diet groups, an indication of a lack of influence on reference memory. Fig. 2b. Conclusion The formulated modified Atkins diet has potential for use in the management of intractable epilepsy in humans. The diet has also shown superiority over the classical ketogenic diet in its ability to not impair visual-spatial learning and memory.

Protective effects of forced exercise against topiramate-induced cognition impairment and enhancement of its antiepileptic activity: molecular and behavioral evidences

Propose/aim of study: Forced exercise can act as a neuroprotective factor and cognitive enhancer. The aim of the current study was to evaluate the effects of forced exercise on topiramate (TPM) induced cognitive impairment and also on TPM anti-seizure activity and neurodegeneration status after seizure. Material and method: Forty adult male rats were divided into four groups receiving normal saline, TPM (100 mg/kg), TPM in combination with forced exercise and forced exercise only respectively for 21 days. MWM test, and PTZ induced seizure were used and some oxidative, inflammatory and apoptotic biomarkers were measured for assessment of experimental animals. Results: Forced exercise in combination with TPM could abolish the TPM induced cognitive impairment and potentiates its anti-seizure activity. Also forced exercise in combination with TPM decreased malondialdehyde (MDA), tumor necrosis factor alpha (TNF-α) and interleukin-1 beta (IL-1β) and Bax protein, while caused increase in superoxide dismutase (SOD), glutathione peroxidase (GPx) and glutathione reductase (GR) activities after PTZ administration. Conclusion: It seems that forced exercise could act as an adjunct therapy with TPM for management of induced cognitive impairment and can also potentiate TPM antiepileptic and neuroprotective effects.

Lacosamide improves biochemical, genotoxic, and mitochondrial parameters after PTZ-kindling model in mice.

This study evaluated the effect of lacosamide (LCM) on biochemical and mitochondrial parameters after PTZ kindling in mice. Male mice were treated on alternative days for a period of 11days with LCM (20, 30, or 40mg/kg), saline, or diazepam (2mg/kg), before PTZ administration (50mg/kg). The hippocampi were collected to evaluate free radicals, the activities of superoxide dismutase (SOD), catalase (CAT), and the mitochondrial complexes I-III, II, and II-III, as well as Bcl-2 and cyclo-oxygenase-2 (COX-2) expressions. Hippocampi, blood, and bone marrow were collected for genotoxic and mutagenic evaluations. LCM 40mg/kg increased latency and decreased percentage of seizures, only on the 3rd day of observation. The dose of 30mg/kg only showed positive effects on the percentage of seizures on the 2nd day of observation. LCM decreased free radicals and SOD activity and the dose of 40mg/kg were able to increase CAT activity. LCM 30 and 40mg/kg improved the enzymatic mitochondrial activity of the complex I-III and LCM 30mg/kg improved the activity of the complex II. In the comet assay, the damage induced by PTZ administration was reduced by LCM 20 and 30mg/kg. The dose of 20mg/kg increased COX-2 expression while the highest dose used, 40mg/kg, was able to reduce this expression when compared to the group treated with LCM 20mg/kg. Although LCM did not produce the antiepileptogenic effect in vivo, it showed the neuroprotective effect against oxidative stress, bioenergetic dysfunction, and DNA damage induced by the repeated PTZ administration.

Anti-epileptic activity of daidzin in PTZ-induced mice model by targeting oxidative stress and BDNF/VEGF signaling

Epilepsy is a complex and multifactorial neurodegenerative disease described by recurrent seizures. Oxidative stress and dysregulation of brain-derived neurotrophic factor (BDNF) and vascular endothelial growth factor (VEGF) are critical factors for the development of epilepsy. Daidzin is well-known for its effective anti-inflammatory and antioxidant potential for centuries. The present study was focused on exploring the anti-epileptic potential of daidzin in the pentylenetetrazole-induced mice model. Daidzin (1, 5, and 10 mg/kg) was administered in the acute study and the dose was optimized. Pretreatment with daidzin remarkably reduced the severity of epileptogenesis in a dose-dependent manner. Moreover, chronic epilepsy was induced in mice by administration of PTZ (35 mg/kg, i.p) every alternative day for 21 days. Results demonstrated that daidzin significantly prevented epileptogenesis and reversed histopathological changes in the hippocampus. It remarkably improved antioxidant (glutathione, glutathione sulfotransferase, superoxide dismutase, and catalase) levels while decreased MDA (malondialdehyde) and nitrite production in the brain. It remarkably improved the expressions of heme oxygenase-1 (HO-1) and BDNF while reduced the expression of VEGF. It remarkably prevented the neuronal apoptosis in the brain tissue. Additionally, spectroscopic analysis such as FTIR (Fourier transform infrared spectroscopy) and DSC (differential scanning calorimetry) revealed that daidzin remarkably prevented PTZ-induced protein damage. HPLC-UV spectrophotometry results demonstrated that there was no peak of aglycone daidzin (metabolite) in the brain sample which specify that the anticonvulsant effect of the compound is due to its direct entry into the brain tissue. Moreover, the molecular docking results showed that daidzin possesses a better binding affinity for ALDH2, estrogen receptor-β, P13k, AKT2, mTORC1, and HIF-1-α proteins. Taken together, the results of the present study showed that daidzin has remarkable neuroprotective and anti-epileptic properties through modulation of oxidative stress, BDNF/VEGF, and apoptotic signaling in the brain tissue of PTZ-kindled mice.

Efficacy and Safety of Dexmedetomidine for Conscious Sedation During Endoscopic Submucosal Dissection

Introduction: Although diazepam DZP and pentazocine Hydrochloride (PTZ) is widely used for sedation during ESD in Japan, there are frequent cases found where the total amount of DZP usage is quite large due to ineffectiveness of sedation. Recently dexmedetomidine (DEX) has become used for sedation during ESD in Japan. DEX has an advantage over DZP in that it does not cause respiratory depression. Therefore, also in our institution DEX has been introduced for sedation during ESD since 2014. In the present study we aimed to investigate the efficacy and safety of DEX for sedation during ESD. Methods: We checked our electronic medical records and extracted 114 cases of ESD between 19th March 2014 and 7th April 2016. These 114 cases were divided into two groups: Group A DEX DPZ and PTZ used concomitantly; Group B, DPZ and PTZ used (without DEX). As the indicator of sedative effectiveness, we investigated the number of body movement which required additional administration of DPZ or PTZ. And we checked adverse events during sedation, such as bradycardia. Results: There were 80 cases extracted in group A, and 34 cases in group B. In group A, the number of body movement was significantly fewer than in group B (A 1.14/h, B 1.18/h). Moreover, the incidence of nausea or vomiting during or three hours after ESD was significantly lower in group A than in group B (2.5% vs 23%, P< 0.001). Whereas, low blood pressure sBP < 80mmHg or bradycardia < 60bpm occurred more frequently in group A than in group B (35% and 28% vs 2% and 0%, respectively; P < 0.001). In 6 cases of low blood pressure we required ephedrine hydrochloride injection. The rest cases of low blood pressure (23 cases) and all the bradycardia cases recovered spontaneously after the end of DEX injection. Conclusion: We concluded that DEX is effective in that it can reduce the number of body movement compared to a DPZ/PTZ method. Although low blood pressure and bradycardia are important adverse events related to DEX, it can be usually managed safely. DEX should be recommended for a sedative agent for ESD.

Pentylenetetrazol-induced seizures strength in diabetic and normal serum glucose elevated male mice

&lt;p class="abstract"&gt;&lt;strong&gt;Background:&lt;/strong&gt; Epilepsy is one of the most important neurological disorders, afflicting both genders during their lifetime. Metabolic disturbances, including hyperglycemia and hypoglycemia, are one of the main reasons of seizures in which frequently have been seen in diabetes mellitus. A large body of literature has investigated correlation between hyperglycemia, hypoglycemia and seizure. However, a definitive conclusion has not been taken, yet. Hence, we developed a rodent model of PTZ-induced seizure in order to investigate about relation between PTZ-induced seizures and glycemic changes, including diabetic and non-diabetic hyperglycemia and hypoglycemia.&lt;/p&gt;&lt;p class="abstract"&gt;&lt;strong&gt;Methods:&lt;/strong&gt; We chose 50 naive, adult male inbred mice of the Balb/c strain (aged 8–10 weeks, weighted 25-35 grams) and divided them into 5 groups, randomly (n=10 in each groups): 1. Control (received saline and citrate buffer). 2. Diabetic group (received STZ 140 mg/kg I.P). 3. Diabetic+Glibenclamide group (received STZ 140 mg/kg I.P and treated with Glibenclamide 1 mg/kg I.P daily). 4. Non-diabetic hyperglycemic group (received glucose "D-dextrose" 2 g/kg I.P 30 min before PTZ administration. 5. Hypoglycemic group (the animals were fasted one day other days during experimental period). Chemical kindling was induced by PTZ injection (35 mg/kg, I.P), every other days (11 periods that lasted 22 days). &lt;/p&gt;&lt;p class="abstract"&gt;&lt;strong&gt;Results:&lt;/strong&gt; Our data shown non-diabetic hyperglycemic mice that had elevated blood glucose levels, were more resistant to seizures compared to control group (p&amp;lt;0.05). Threshold and duration of the second phase of the seizures in non-diabetic hyperglycemic mice were increased (p&amp;lt;0.001). Moreover, threshold of the phase 5 was enhanced (p&amp;lt;0.001).&lt;strong&gt; &lt;/strong&gt;Again, hypoglycemic mice had statistically significant decrease in threshold of phase 5 compared to control group (p&amp;lt;0.05).&lt;/p&gt;&lt;strong&gt;Conclusions:&lt;/strong&gt; We found that acute non-diabetic hyperglycemia not only have had no aggravating effects on seizure susceptibility but also have shown anticonvulsive effects. As well, we found that hypoglycemia has decreased threshold of phase 5 in challenge dose, i.e. onset of the most severe phase of the seizures was accelerated.

Protective Effect of Nerolidol Against Pentylenetetrazol-Induced Kindling, Oxidative Stress and Associated Behavioral Comorbidities in Mice

The present study was aimed to investigate the effect of nerolidol on the development of kindling and associate oxidative stress and behavioral comorbidities. Kindling was induced by repeated injections of a sub-convulsive dose of pentylenetetrazol (PTZ-35mg/kg; i.p.), at an interval of 48 ± 2h for 43days (21 injections). Nerolidol was administered daily in three doses (12.5, 25 and 50mg/kg) along with alternate day PTZ injection. To access behavioral comorbidities, animals were subjected to tail suspension test (TST) and passive shock avoidance (PSA) test to evaluate the associated depression and memory impairment respectively on the last day of PTZ administration. Following behavioral assessment, neurotransmitter level and oxidative stress markers were evaluated in brain. The results showed that nerolidol significantly suppressed the progression of kindling. Also, nerolidol ameliorates the kindling associated depression and memory impairment as indicated by decreased immobility time and increased step down latency, respectively, as compared to vehicle control animals. Further, these behavioral observations were complimented with corresponding neurochemical and oxidative stress markers changes. In conclusion, the results of present study showed that nerolidol treatment has protective effect against PTZ-induced kindling and associated oxidative stress and behavioral comorbidities.

Anticonvulsant and anxiolyic activities of ethyl acetate fraction of Cassia fistula Linn. pods in mice

Context: Cassia fistula L. (Leguminacea) is used by Indian and Tanzanian traditional healers for treating various ailments related to the central nervous system. Aims: The present study aimed to evaluate the anticonvulsant and anxiolytic activity of the ethyl acetate fraction obtained from a hydroalcoholic extraction of Cassia fistula pods (EAFCF) and thereby to provide scientific validation for its traditional use. Methods: Preliminary phytochemical analysis and estimation of the flavonoid content of the ethyl acetate fraction was performed. Anticonvulsant activity was assessed by the subcutaneous pentylenetetrazole test (s.c. PTZ test). Anxiolytic activity was assessed by elevated plus maze (EPM) and open field tests (OFT). The sedative and motor toxicity was evaluated by a phenobarbitone induced sleep test and rotarod behavior respectively. Results: Photochemical analysis revealed the presence of a high flavanoid content in the ethyl acetate fraction. Treatment of EAFCF (50 and 100 mg/kg) significantly increased the latency to the onset of minimal clonic seizure and generalized tonic clonic seizure and animals were completely protected from death due to PTZ administration. Administration of EAFCF at the dose of 100 mg/kg markedly increased the open arm entries and time spent in open arm in EPM. In OFT, EAFCF increased the number of central squares crossed and time spent in the central compartment. EAFCF in the doses used in this experiment did not produce sedation or motor toxicity. Conclusion: The results obtained herein clearly indicate the anticonvulsant and anxiolytic activity of EAFCF which may be due to the high flavonoid content. These findings give the scientific support for common use of this plant for treating epilepsy and anxiety.

Naringin ameliorates pentylenetetrazol-induced seizures and associated oxidative stress, inflammation, and cognitive impairment in rats: Possible mechanisms of neuroprotection

Oxidative stress and cognitive impairment are associated with PTZ-induced convulsions. Naringin is a bioflavonoid present in the grapefruit. It is a potent antioxidant, and we evaluated its effect on PTZ-induced convulsions. Rats were pretreated with normal saline, naringin (20, 40, and 80mg/kg, i.p.), or diazepam (5mg/kg, i.p.) 30min prior to the administration of PTZ. The administration of PTZ induced myoclonic jerks and generalized tonic–clonic seizures (GTSs). We observed that naringin significantly prolonged the induction of myoclonic jerks dose-dependently. Naringin (80mg/kg, i.p.) pretreatment protected all rats, and this protective effect was annulled by the GABAA receptor antagonist, flumazenil. In addition, naringin reduced brain MDA and TNF-α levels and conserved GSH. The pretreatment also enhanced the performance of rats in the passive avoidance task. Our observations highlight the antioxidant, antiinflammatory, and anticonvulsant potential of naringin. Also, naringin modulates the GABAA receptor to produce anticonvulsant effects and to ameliorate cognitive impairment.

Anticonvulsant effects of bis-1,4-dihydropyridines and the probable role of L-type calcium channels suggested by docking simulations

The influx/efflux of calcium (Ca2+) ions through channels in cellular membranes plays a pivotal role in many physiological and physiopathological processes. Among these are those involved in the physiopathology of epileptic seizures. Hence, the control of permeability of ions through these channels is considered a strategy for the development of anticonvulsant drugs. According to the previous reports, dihydropyridine derivatives have proven to be Ca2+ channel blockers and have anticonvulsive properties, presumably by means of their action on L-type Ca2+ channels (LCCs). The aim of the present study was to determine the anticonvulsant effects of four bis-1,4-dihydropyridines (bis-DHPs) in male CF1 mice (25–30 g bw) using two experimental models: maximal electroshock (MES, which induces convulsions with an alternating current of 60 Hz) and pentylenetetrazole administration (PTZ, 90 mg/kg administered i.p.). Additionally, the binding mode was explored with a docking study on a 3-D model of an LCC. The four bis-DHPs herein tested showed a protective effect in relation to the number of convulsions induced by MES, the recovery time after a convulsion, and the duration of the tonic phase. However, only bis-DHPs 01–03 reduced the duration of the clonic phase, and these compounds also produced a significant protective effect against the convulsions induced by PTZ administration. This effect may be related to the interaction of bis-DHPs with a cluster of aromatic residues (Tyr1152, Tyr1463, and Phe1159) involved in blocking calcium flow, as suggested by docking studies.

Erythropoietin pretreatment suppresses seizures and prevents the increase in inflammatory mediators during pentylenetetrazole-induced generalized seizures

Erythropoietin (EPO) suppresses epileptic seizures, but the mechanism is unclear. The search for novel targets in the therapy of epilepsy has focused recently on brain inflammation since brain inflammation and the associated blood–brain barrier (BBB) damage appears to be an integral part of epilepsy pathophysiology. We examined the effects of EPO on proinflammatory mediators in brain and serum in PTZ-induced generalized seizure model. The inflammation markers (IL-1β, TNF-α, IL-6, IL-10), BBB and neuron damage markers (S100B, Neuron specific enolase; NSE, respectively) in serum and brain of Sprague–Dawley male rats were examined with the ELISA method. Nitric oxide synthase (NOS) isoforms were investigated immunohistochemically in hippocampus. EPO treatment 4 h and 24 h before PTZ administration had diverse effects. EPO treatment 4 h before PTZ administration elongated the seizure latency, decreased the inflammation and damage markers in serum and brain significantly, whereas EPO treatment 24 h before PTZ administration lowered inflammation and damage markers to control levels and decreased the seizure stage. PTZ-induced seizures increased inducible NOS (iNOS) activity and decreased endothelial NOS (eNOS) activity in hippocampus. Both EPO pretreatments reversed these effects. These findings, i.e., decreased iNOS activity and increased eNOS activity by EPO suggest the first time that the favorable effect of EPO pretreatment on inflammatory mediators triggered by PTZ-induced seizures. This can provide further insight into epilepsy treatment and new prophylactic strategies against epilepsy risk.

Mygalin: A New Anticonvulsant Polyamine in Acute Seizure Model and Neuroethological Schedule

Polyamines are compounds that interact with ionotropic receptors, mainly modulating the NMDA receptor, which is strictly related to many neurologic diseases such as epilepsy. Consequently, polyamines rise as potential neuropharmacological tools in the prospection of new therapeutic drugs. In this paper, we report on the biological activity of synthetic polyamine Mygalin, which was tested as an anticonvulsant in model of chemically induced seizures. Male Wistar rats were injected with vehicle, diazepam, MK-801 or Mygalin at different doses followed by Pentylenetetrazole or N-Methyl-D-Aspartate administration. Mygalin presented protection against seizures induced by both NMDA injections and PTZ administration by 83.3% and 16.6%, respectively. Moreover, it prolonged the onset of tonic-clonic seizures induced by PTZ. Furthermore, it was tested in neuroethological schedule evaluating possible side-effects and it presented mild changes in Open Field, Rotarod and Morris Water Maze tests when compared to available anticonvulsant drugs. The mechanism underlying the anticonvulsant effect of Mygalin is noteworthy of further investigation, nevertheless, based on these findings, we hypothesize that it may be wholly or in part due to a possible NMDA receptor antagonism. Altogether, the results demonstrate that Mygalin has an anticonvulsant activity that may be an important tool in the study of prospection of therapeutics in epilepsy neuropharmacology.

Increased seizure latency and decreased severity of pentylenetetrazol-induced seizures in mice after essential oil administration.

The effect of pretreatment with essential oils (EOs) from eight aromatic plants on the seizure latency and severity of pentylenetetrazol- (PTZ-) induced seizures in mice was evaluated. Weight-dependent doses of Rosmarinus officinalis, Ocimum basilicum, Mentha spicata, Mentha pulegium, Lavandula angustifolia, Mentha piperita, Origanum dictamnus, and Origanum vulgare, isolated from the respective aromatic plants from NE Greece, were administered 60 minutes prior to intraperitoneal (i.p.) injection of a lethal dose of PTZ to eight respective groups of Balb-c mice. Control group received only one i.p. PTZ injection. Motor and behavioral activity of the animals after EOs administration, development of tonic-clonic seizures, seizure latency and severity, and percentage of survival after PTZ administration were determined for each group. All groups of mice treated with the EOs showed reduced activity and stability after the administration of the oil, except for those treated with O. vulgare (100% mortality after the administration of the oil). After PTZ administration, mice from the different groups showed increased latency and reduced severity of seizures (ranging from simple twitches to complete seizures). Mice who had received M. piperita demonstrated no seizures and 100% survival. The different drastic component and its concentration could account for the diversity of anticonvulsant effects.

Parawixin2, a novel non-selective GABA uptake inhibitor from Parawixia bistriata spider venom, inhibits pentylenetetrazole-induced chemical kindling in rats

The aims of the present work were to investigate the effects of the repeated administration of Parawixin2 (2-amino-5-ureidopentanamide; formerly FrPbAII), a novel GABA and glycine uptake inhibitor, in rats submitted to PTZ-induced kindling. Wistar rats were randomly divided in groups (n=6–8) for different treatments. Systemic injections of PTZ were administered every 48h in the dose of 33mg/kg; i.p., that is sufficient to induce fully kindled seizures in saline i.c.v. treated rats in a short period of time (28 days). Treatments in two types of positive controls (diazepam – DZP and nipecotic acid – NA groups) consisted in daily systemic injections of DZP (2mg/kg; i.p.) or i.c.v. injections of NA (12μg/μL), while in experimental groups in daily i.c.v. injections of different doses of Parawixin2 (0.15; 0.075; 0.015μg/μL). Seizures were analyzed using the Lamberty & Klitgaard score and kindling was considered as established after at least three consecutive seizures of score 4 or 5. Cumulative seizure scores for each group were analyzed using repeated measures of ANOVA followed by Tukey test. PTZ induced 4 and 5-score seizures after 12 injections in saline treated rats, whereas daily injection of Parawixin2 inhibited the onset of seizures in a dose dependent manner. Also, the challenging administration of PTZ did not raise seizure score in animals treated with the highest dose of Parawixin2 or those treated with DZP or NA. These findings together with previous data from our laboratory show that Parawixin2 could be a useful probe to design new antiepileptic drugs.