Pentylenetetrazole Treatment Research Articles

Ethosuximide Reduces Mortality and Seizure Severity in Response to Pentylenetetrazole Treatment During Ethanol Withdrawal.

We recently demonstrated that T-type calcium channels are affected by alcohol abuse and withdrawal. Treatment with ethosuximide, an antiepileptic drug that blocks T-type calcium channels, reduces seizure activity induced by intermittent ethanol exposures and withdrawals. Here, we expand on these findings to test whether ethosuximide can reduce the sensitivity to pentylenetetrazole-induced seizures during ethanol withdrawal. We used an intermittent ethanol exposure model to produce withdrawal-induced hyperexcitability in DBA/2J mice. Ethosuximide (250 mg/kg) reduced seizure severity in mice undergoing ethanol withdrawal with concurrent PTZ treatment (20 mg/kg). Importantly, ethosuximide did not produce rebound excitability and protected against ethanol withdrawal-induced mortality produced by concurrent PTZ treatment (40 mg/kg). These results, in addition to previous preclinical findings, suggest that ethosuximide should be further evaluated as a safe, effective alternative to benzodiazepines for the treatment of alcohol withdrawal.

Ultrastructural changes to rat hippocampus in pentylenetetrazol- and kainic acid-induced status epilepticus: A study using electron microscopy

A pentylenetetrazol (PTZ)-induced status epilepticus model in rats was used in the study. The brains were studied one month after treatment. Ultrastructural observations using electron microscopy performed on the neurons, glial cells, and synapses, in the hippocampal CA1 region of epileptic brains, demonstrated the following major changes over normal control brain tissue. (i) There is ultrastructural alterations in some neurons, glial cells and synapses in the hippocampal CA1 region. (ii) The destruction of cellular organelles and peripheral, partial or even total chromatolysis in some pyramidal cells and in interneurons are observed. Several astrocytes are proliferated or activated. Presynaptic terminals with granular vesicles and degenerated presynaptic profiles are rarely observed. (iii) The alterations observed are found to be dependent on the frequency of seizure activities following the PTZ treatment. It was observed that if seizure episodes are frequent and severe, the ultrastructure of hippocampal area is significantly changed. Interestingly, the ultrastructure of CA1 area is found to be only moderately altered if seizure episodes following the status epilepticus are rare and more superficial; (iv) alterations in mitochondria and dendrites are among the most common ultrastructural changes seen, suggesting cell stress and changes to cellular metabolism. These morphological changes, observed in brain neurons in status epilepticus, are a reflection of epileptic pathophysiology. Further studies at the chemical and molecular level of neurotransmitter release, such as at the level of porosomes (secretory portals) at the presynaptic membrane, will further reveal molecular details of these changes.

Abstract W P389: Placental Ischemia Increases Seizure Susceptibility in Pregnant Rats

Eclampsia is diagnosed in preeclamptic patients who develop convulsions and/or unexplained coma during pregnancy or postpartum. It is one of the leading causes of maternal and infant morbidity and mortality accounting for about 13% of all maternal deaths worldwide. While several factors contributing to the pathogenesis of preeclampsia have been identified, little is known about the mechanisms contributing to the pathophysiology of eclampsia, partly due to the lack of suitable animal models of eclampsia. The aim of this study was to test the hypothesis that placental ischemia, induced by reducing utero-placental perfusion, increases susceptibility to seizures and cerebral edema. Pentylenetetrazol (PTZ), a pro-convulsive drug, was injected into pregnant and placental ischemic rats (40 mg/kg, i.p.) on gestational day 19 followed by video monitoring of rats for seizure activity for a duration of 30 minutes. Seizure scoring was blindly conducted. Results indicate the placental ischemic rats (n=8) have reduced latency to first seizure (264.5 ± 78.7s) compared to normal pregnant rats (n=7) (835.7 ± 246.6s; p < 0.05). Placental ischemia increased brain water content in the cerebrum (78.8 ± 0.1%) compared to the normal pregnant group (78.4 ± 0.1%; p < 0.05) while PTZ treatment significantly increased brain water content in both the pregnant (78.8 ± 0.1%; p < 0.05) and placental ischemic group (78.9 ± 0.1%; p < 0.01). These data demonstrate that placental ischemia is associated with increased susceptibility to seizures and edema formation; thus the rat model of placental ischemia represents an excellent model for studying mechanisms of eclampsia-like symptoms. Further studies are required to elucidate the exact mechanisms contributing to increased seizure susceptibility following placental ischemia.

Low brain ascorbic acid increases susceptibility to seizures in mouse models of decreased brain ascorbic acid transport and Alzheimer's disease

Seizures are a known co-occurring symptom of Alzheimer's disease, and they can accelerate cognitive and neuropathological dysfunction. Sub-optimal vitamin C (ascorbic acid) deficiency, that is low levels that do not lead the sufferer to present with clinical signs of scurvy (e.g. lethargy, hemorrhage, hyperkeratosis), are easily obtainable with insufficient dietary intake, and may contribute to the oxidative stress environment of both Alzheimer's disease and epilepsy. The purpose of this study was to test whether mice that have diminished brain ascorbic acid in addition to carrying human Alzheimer's disease mutations in the amyloid precursor protein (APP) and presenilin 1 (PSEN1) genes, had altered electrical activity in the brain (electroencephalography; EEG), and were more susceptible to pharmacologically induced seizures. Brain ascorbic acid was decreased in APP/PSEN1 mice by crossing them with sodium vitamin C transporter 2 (SVCT2) heterozygous knockout mice. These mice have an approximately 30% decrease in brain ascorbic acid due to lower levels of SVCT2 that supplies the brain with ASC. SVCT2+/-APP/PSEN1 mice had decreased ascorbic acid and increased oxidative stress in brain, increased mortality, faster seizure onset latency following treatment with kainic acid (10 mg/kg i.p.), and more ictal events following pentylenetetrazol (50 mg/kg i.p.) treatment. Furthermore, we report the entirely novel phenomenon that ascorbic acid deficiency alone increased the severity of kainic acid- and pentylenetetrazol-induced seizures. These data suggest that avoiding ascorbic acid deficiency may be particularly important in populations at increased risk for epilepsy and seizures, such as Alzheimer's disease.

Dynamic expression patterns of ATF3 and p53 in the hippocampus of a pentylenetetrazole-induced kindling model.

Epilepsy is a common and often deleterious neurological condition. Emerging evidence has demonstrated the roles of innate immunity and the associated inflammatory processes in epilepsy. In a previous study, we found that Toll-like receptors (TLRs) are upregulated and promote mossy fiber sprouting (MFS) in an epileptic model. As downstream effectors of TLRs, the activating transcription factor 3 (ATF3) and p53 proteins were shown to be involved in neurite outgrowth. In the present study, we hypothesized that ATF3 and p53 participate in the process of epilepsy and can affect MFS. To investigate this hypothesis, we examined the expression of ATF3 and p53 in hippocampal tissues of rats kindled by pentylenetetrazole (PTZ) using immunofluorescence, immunohistochemistry and western blotting. MFS was evaluated by Timm staining in the hippocampus. Results from these experiments revealed that expression of ATF3 and p53 is significantly higher (p<0.05) in the CA3 area of the hippocampus in the PTZ-treated group compared to the control group. ATF3 expression gradually increased from 3 days to 4 weeks, peaked at 4 weeks and decreased slightly at 6 weeks in the PTZ group, while the expression of p53 was maintained at similar levels at different time-points following PTZ treatment. No obvious difference in the expression of these proteins was observed between the PTZ and the control group in the dentate gyrus (DG) area (p>0.05). The degree of MFS in the PTZ group peaked at 4 weeks and was maintained at a high level until 6 weeks post-PTZ treatment. In conclusion, ATF3 and p53 may be involved in the occurrence of seizure and play critical roles in MFS in the PTZ kindling model.

EFFECT OF SOME ANTIDIABETIC DRUGS ON BIOCHEMICAL PARAMETERS IN EXPERIMENTALLY INDUCED EPILEPTIC RATS

The present study was conducted to evaluate the effect of glibenclamide and metformin on some biochemical parameters in rats induced epilepsy. Male Wister was induced epilepsy by injection of pentylenetetrazole (PTZ) at a dose 100 mg/kg of body weight, the rats randomly divided into 3 groups (10-12 rat/group). The group 1: leaved without treatment and served as control group; Group 2: was treated with glibenclamide 5 mg/kg.b.w.; Group 3: was treated with metformin 150 mg/kg.b.w. All treatments were once daily for 1 week, blood samples were collected at 3, 24 hours, and week after induced of epilepsy. The results show that treated with PTZ leads to significant decrease in glucose level in all times after treatment, and significantly decreased level of cholesterol after 3 hours, and a week after treatment, while level of albumin was significantly decreased after a week of treatment, also PTZ treatment increased level of aspartate aminotransferase (AST) in all times after treatment, while level of alanine aminotransferase (ALT) was significantly increased after 3 hours, then significantly decreased after a week of treatment. PTZ treatment doesn't show any effect on levels of total protein, and globulin. Treatment with glibenclamide leads to significant increase level of glucose in all times after treatment, also level of cholesterol was significantly increased at 3, 24 hours after treatment with glibenclamide. Level of (AST) was significantly decreased in all times after treatment with glibenclamide, but level of (ALT) was increased only after a week of treatment, glibenclamide don’t cause any effect on levels total protein, albumin, and globulin. Treatment with metformin leads to significantly decreased level of glucose after 3, 24 hours of treatment, with significant increase after a week of treatment, while level of cholesterol was significantly increased after 3 hours, and significantly decreased after 24 hours of treatment. Levels of total protein and globulin were increased significantly after 3 hours only, level of albumin significant decrease after 24 hours treatment, also metformin lead to significantly decreased level of (AST) after 3 hours, and significantly increased after a week of treatment, while (ALT) level significantly increased after 24 hour, and week of treatment. These results indicate that glibenclamide and metformin have good roles in control of epilepsy-induced by PTZ in rats through several significant changes of biochemical parameters.

Decreased Seizure Threshold in an Eclampsia-Like Model Induced in Pregnant Rats with Lipopolysaccharide and Pentylenetetrazol Treatments

ObjectiveEclampsia is a poorly understood but potentially fatal complication of pregnancy. Research to date on this disorder has been hampered by the lack of a suitable animal model. To correct this deficiency, this report describes the generation of a rat eclampsia-like model using pentylenetetrazol (PTZ) in a previously established rat preeclampsia model.MethodRats were administered lipopolysaccharide (1.0 µg/kg) by tail vein injection on gestational day 14 to establish preeclampsia (PE). PE and control rats (non-pregnant, NP; normal-pregnant, P) were injected intraperitoneally (i.p.) with PTZ (40 mg/kg) to induce seizures. In separate experiments, MgSO4 (270 mg/kg IP) was injected in advance of PTZ into PE rats to observe its effect on PTZ-induced seizures.ResultsPE conditions were verified in rats after LPS administration by significantly higher blood pressure (P<0.01) and urinary albumin excretion (P<0.05), elevated sFlt-1 (P<0.05) and decreased PlGF serum levels (P<0.05), and evidence of hepatic dysfunction compared to control groups. PTZ successfully induced seizure activity in all groups studied. Latency to seizure was significantly (P<0.01) less in the PE-PTZ group (73.2±6.6 sec.) than in PTZ-treated controls (107.0±7.4 sec.). Pretreatment with MgSO4 prolonged (P<0.05) latency to seizure, shortened seizure duration and decreased seizure rates. Significant increased (P<0.05) in the serum levels of the inflammatory cytokines TNF-α and IL-1β in PE and PE-PTZ groups, and decreased (P<0.05) in their levels following MgSO4 administration.ConclusionThis PTZ-induced eclampsia-like rat model is comparable to the human condition of eclampsia and may serve as a useful research tool for future studies of this disease. The increased inflammatory cytokines in preeclampsia are coincident with a decreased threshold for PTZ-induced seizures, suggesting that an inflammatory mechanism may contribute to the susceptibility to seizure activity and inflammation might have an important role in eclampsia.

Cannabidivarin (CBDV) suppresses pentylenetetrazole (PTZ)-induced increases in epilepsy-related gene expression

To date, anticonvulsant effects of the plant cannabinoid, cannabidivarin (CBDV), have been reported in several animal models of seizure. However, these behaviourally observed anticonvulsant effects have not been confirmed at the molecular level. To examine changes to epilepsy-related gene expression following chemical convulsant treatment and their subsequent control by phytocannabinoid administration, we behaviourally evaluated effects of CBDV (400 mg/kg, p.o.) on acute, pentylenetetrazole (PTZ: 95 mg/kg, i.p.)-induced seizures, quantified expression levels of several epilepsy-related genes (Fos, Casp 3, Ccl3, Ccl4, Npy, Arc, Penk, Camk2a, Bdnf and Egr1) by qPCR using hippocampal, neocortical and prefrontal cortical tissue samples before examining correlations between expression changes and seizure severity. PTZ treatment alone produced generalised seizures (median: 5.00) and significantly increased expression of Fos, Egr1, Arc, Ccl4 and Bdnf. Consistent with previous findings, CBDV significantly decreased PTZ-induced seizure severity (median: 3.25) and increased latency to the first sign of seizure. Furthermore, there were correlations between reductions of seizure severity and mRNA expression of Fos, Egr1, Arc, Ccl4 and Bdnf in the majority of brain regions in the CBDV+PTZ treated group. When CBDV treated animals were grouped into CBDV responders (criterion: seizure severity ≤3.25) and non-responders (criterion: seizure severity >3.25), PTZ-induced increases of Fos, Egr1, Arc, Ccl4 and Bdnf expression were suppressed in CBDV responders. These results provide the first molecular confirmation of behaviourally observed effects of the non-psychoactive, anticonvulsant cannabinoid, CBDV, upon chemically-induced seizures and serve to underscore its suitability for clinical development.

Elevated expression of pleiotrophin in pilocarpine-induced seizures of immature rats and in pentylenetetrazole-induced hippocampal astrocytes in vitro

Pleiotrophin (PTN) is a secreted extracellular matrix (ECM)-associated cytokine that has emerged as an important neuromodulator with multiple neuronal functions. In the present study, we detected and compared the dynamic expression of PTN in the hippocampus and adjacent cortex of immature rats with pilocarpine-induced epilepsy. Moreover, we also confirmed the results by examining PTN expression in hippocampal astrocytes cultured in the presence of pentylenetetrazole (PTZ). Immunohistochemistry showed faint immunostaining of PTN in the control hippocampus and adjacent cortex. Notably, PTN immunoreactivity began to increase in relatively small cells in the hippocampus and adjacent cortex at 2h and 3 weeks after seizures, and the labeling intensity reached the maximum level in the hippocampus and adjacent cortex at 8 weeks after seizures. Furthermore, we also found that PTZ treatment significantly reduced astrocytic viability in a dose-dependent manner and time-dependently increased expression levels of PTN in hippocampal astrocytes. In conclusion, our data suggest that increased expression of PTN in the brain tissues may be involved in epileptogenesis.

Seizure-induced reduction in PIP3 levels contributes to seizure-activity and is rescued by valproic acid

Phosphatidylinositol (3–5) trisphosphate (PIP3) is a central regulator of diverse neuronal functions that are critical for seizure progression, however its role in seizures is unclear. We have recently hypothesised that valproic acid (VPA), one of the most commonly used drugs for the treatment of epilepsy, may target PIP3 signalling as a therapeutic mode of action. Here, we show that seizure induction using kainic acid in a rat in vivo epilepsy model resulted in a decrease in hippocampal PIP3 levels and reduced protein kinase B (PKB/AKT) phosphorylation, measured using ELISA mass assays and Western blot analysis, and both changes were restored following VPA treatment. These finding were reproduced in cultured rat hippocampal primary neurons and entorhinal cortex–hippocampal slices during exposure to the GABA(A) receptor antagonist pentylenetetrazol (PTZ), which is widely used to generate seizures and seizure-like (paroxysmal) activity. Moreover, VPA's effect on paroxysmal activity in the PTZ slice model is blocked by phosphatidylinositol 3-kinase (PI3K) inhibition or PIP2 sequestration by neomycin, indicating that VPA's efficacy is dependent upon PIP3 signalling. PIP3 depletion following PTZ treatment may also provide a positive feedback loop, since enhancing PIP3 depletion increases, and conversely, reducing PIP3 dephosphorylation reduces paroxysmal activity and this effect is dependent upon AMPA receptor activation. Our results therefore indicate that PIP3 depletion occurs with seizure activity, and that VPA functions to reverse these effects, providing a novel mechanism for VPA in epilepsy treatment.

Short‐term treatment with the GABAA receptor antagonist pentylenetetrazole produces a sustained pro‐cognitive benefit in a mouse model of Down's syndrome

Down's syndrome is a common genetic cause of intellectual disability, for which there are no drug therapies. Mechanistic studies in a model of Down's syndrome [Ts65Dn (TS) mice] demonstrated that impaired cognitive function was due to excessive neuronal inhibitory tone. These deficits were normalized by low doses of GABAA receptor antagonists in adult animals. In this study, we explore the therapeutic potential of pentylenetetrazole, a GABAA receptor antagonist with a history of safe use in humans. Long-term memory was assessed by the novel object recognition test in different cohorts of TS mice after a delay following a short-term chronic treatment with pentylenetetrazole. Seizure susceptibility, an index of treatment safety, was studied by means of EEG, behaviour and hippocampus morphology. EEG spectral analysis was used as a bio-marker of the treatment. PTZ has a wide therapeutic window (0.03-3 mg·kg(-1)) that is >10-1000-fold below its seizure threshold and chronic pentylenetetrazole treatment did not lower the seizure threshold. Short-term, low, chronic dose regimens of pentylenetetrazole elicited long-lasting (>1 week) normalization of cognitive function in young and aged mice. Pentylenetetrazole effectiveness was dependent on the time of treatment; cognitive performance improved after treatment during the light (inactive) phase, but not during the dark (active) phase. Chronic pentylenetetrazole treatment normalized EEG power spectra in TS mice. Low doses of pentylenetetrazole were safe, produced long-lasting cognitive improvements and have the potential of fulfilling an unmet therapeutic need in Down's syndrome.

Dose Dependent Efficacy of Lacosamide in Protection of Pentylenetetrazol Induced Seizure in Rats

Epilepsy is a common and frequently devastated disorder affecting 0.5 to 1% of the population with annual incidence rate of approximately 30 to 50 per 1, 00,000 per year. Lacosamide is a novel anti-epileptic drug, recently been licensed for adjunctive therapy of partial or secondary generalized seizures. Objective: To evaluate dose dependent efficacy of lacosamide in protection of Pentylenetetrazol (PTZ) induced seizures in rats. Method: The study was conducted in albino rats of either sex, weighing between 100-150 gm. The animals were grouped into 6 groups, each compromised of 8 animals. Group I was treated with requisite volume of normal saline, group II received pentylenetetrazol (80mg/kg, i.p). Animals in group III, IV,V and VI were pretreated with graded doses of lacosamide (3,10,30& 50mg/kg i.p),thirty minutes later, the lacosamide pretreated groups were treated with pentylenetetrazol (80mg/kg/i.p). Results: It was found that animals in control group were normal, while the animals with PTZ treatment showed convulsions followed by mortality. However in group III 38%, group IV 60%, group V 88% & group VI 100% protection was observed with lacosamide against PTZ induced seizures. Conclusion: So, in our study we observed that in the doses of 30 and 50mg/kg, ip, lacosamide increased the seizure threshold and showed protection against the minimal seizure.

Increased Seizure Susceptibility in a Mouse with Diacylglycerol Kinase &amp;lt;i&amp;gt;β&amp;lt;/i&amp;gt; Deficiency

Diacylglycerol kinase (DGK) is an enzyme that converts diacylglycerol to phosphatidic acid. Several DGK isoforms have been implicated in the pathogenesis of seizure, but the role of DGKβ in seizure is unknown. In the present study, we investigated the involvement of DGKβ in seizure using DGKβ knockout (KO) mice. Seizures were more severe in DGKβ KO mice than in wild-type (WT) mice after pentylenetetrazol (PTZ) treatment and after kainic acid treatment, but there were no differences in latency to seizure. The expression levels of DGKβ in the hippocampal CA1, CA3, or DG areas did not differ between PTZ (60 mg/kg) treatment and saline treatment. There were fewer parvalbumin-positive interneurons in the hippocampal CA3 area in DGKβ KO mice than in control WT mice, which might partly account for the increased seizure susceptibility displayed by DGKβ KO mice. These results suggest that DGKβ may play a pivotal role in the development of the relevant interneurons, and that on inherent deficiency of DGKβ increases the animal’s sensitivity to seizure-inducing stimuli.

Antiepileptic drugs prevent changes in adenosine deamination during acute seizure episodes in adult zebrafish

Adenosine is an endogenous modulator of brain functions, which presents anticonvulsant properties. In addition, its levels can be increased during neural injury. The modulation of extracellular adenosine levels by ectonucleotidase and adenosine deaminase (ADA) activities may represent a key mechanism in the control of epileptogenesis. In the present study, we investigated the effects of acute seizure episodes and antiepileptic drug (AED) treatments on ectonucleotidases and ADA activities in adult zebrafish brain. Our data have demonstrated that pentylenetetrazole (PTZ)-induced seizures did not alter ATP, ADP, and AMP hydrolysis in brain membrane fractions. However, there was a significant increase on ecto-ADA and soluble ADA activities in PTZ-treated animals immediately after a clonus-like convulsion and loss of posture, which are typical behavioral changes observed in Stage 3. Furthermore, our results have demonstrated that AED pretreatments prevented the stimulatory effect promoted by PTZ exposure on ADA activities. The PTZ and AED treatments did not promote alterations on ADA gene expression. Interestingly, when exposed to PTZ, animals pretreated with AEDs showed longer latency to reach the clonus-like seizure status, which is an effect that matches the suppression of the increase of ADA activity promoted by the AEDs. These data suggest that the adenosine deamination could be involved in the control of seizure development in zebrafish and may be modulated by AED treatments.

Characterization of Seizures Induced by Acute and Repeated Exposure to Tetramethylenedisulfotetramine

Tetramethylenedisulfotetramine (tetramine; TETS) is a potent convulsant poison that is considered to be a chemical threat agent. To provide a basis for the investigation of antidotes for TETS-induced seizures, we characterized the convulsant activity of TETS in mice and rats when administered by the intraperitoneal, intravenous, oral, and intraventricular routes as a single acute dose and with repeated sublethal doses. In mice, parenteral and oral TETS caused immobility, myoclonic body jerks, clonic seizures of the forelimbs and/or hindlimbs, tonic seizures, and death. The CD₅₀ values for clonic and tonic seizures after oral administration were 0.11 and 0.22 mg/kg, respectively. Intraventricular administration of TETS (5-100 μg) in rats also caused clonic-tonic seizures and death. In mice, repeated sublethal doses of TETS at intervals of 2, 24, and 48 h failed to result in the development of persistent enhanced seizure responsivity ("kindling") as was observed with repeated pentylenetetrazol treatment. In mice, sublethal doses of TETS that produced clonic seizures did not cause observable structural brain damage as assessed with routine histology and Fluoro-Jade B staining 7 days after treatment. However, 1 to 3 days after a single convulsant dose of TETS the expression of glial fibrillary acidic protein, an astrocyte marker, and ionized calcium binding adaptor molecule 1, a microglia marker, were markedly increased in cortex and hippocampus. Although TETS doses that are compatible with survival are not associated with overt evidence of cellular injury or neurodegeneration, there is transient reactive astrocytosis and microglial activation, indicating that brain inflammatory responses are provoked.

Impaired Memory Following Repeated Pentylenetetrazol Treatments in Kindled Mice

Epilepsy is characterized by recurrent seizures, which are caused by excessive discharges from cerebral neurons. Currently, antiepileptic drugs that possess sodium channel blocking activities and also mediate GABA-ergic systems are primarily used to prevent epileptic seizure. However, approximately 40% of patients with epilepsy suffer from interictal psychiatric comorbidities in clinical practice. Furthermore, it is unclear whether epilepsy is associated with psychic function. The aim of the present study was to clarify the effects of kindling-induced epileptic seizures on psychic functioning using behavioral pharmacological tests. Pentylenetetrazol (PTZ)-kindled mice demonstrated no significant differences in locomotor activity and muscle relaxation compared with naïve mice. PTZ-kindled mice also demonstrated cognitive impairment in the objective location test, but no significant effects of PTZ-kindling were observed in the Y-maze test. These findings suggested that PTZ-kindling impairs reference memory, but not working memory. These results suggest that, with respect to their psychic functioning, PTZ-kindled mice have specific characteristics.

Dual protective effect of Passiflora incarnata in epilepsy and associated post-ictal depression

Ethnopharmacological relevancePassiflora incarnata L. (Passifloraceae) has been used for the treatment of epilepsy in several traditional systems of medicine. Aim of the studyThe aerial parts of Passiflora incarnata contain multiple bioactive metabolites such as, flavonoids (like, chrysin that show CNS depressant activity by agonizing GABA–benzodiazepine receptor), amino acids (like, GABA), harmala alkaloids (reversible monoamine oxidase-A inhibitor), etc. In view of this, the present study was designed to investigate dual protective effect of the hydroethanolic extract of Passiflora incarnata in pentylenetetrazol (PTZ)-induced seizure and associated post-ictal depression. Materials and methodsDifferent groups of mice were administered with repeated subconvulsive doses of PTZ (50mg/kg; i.p.) at an interval of 5 days for 15 days. From 5th to 15th day the animals in different groups were administered daily with varying doses of hydroethanolic extract of Passiflora incarnata (150, 300, and 600mg/kg; i.p.), diazepam (2mg/kg; i.p.) and vehicle. On every 5th day, after PTZ treatment, seizure severity (score) was noted. Following convulsive episodes the locomotor activity (using actophotometer) and immobility period (using forced swim test) were also determined. On 15th day after behavioral assessment, the brain serotonin and noradrenaline levels were determined using spectrofluorometric methods. ResultsTreatment with the extract significantly (p<0.05) reduced the seizure severity and immobility period as compared to vehicle control, in a dose and time-dependent manner. Moreover, the extract treatment retained the serotonin and noradrenaline levels of the brain. ConclusionsThe results of present study concluded that the hydroethanolic extract of Passiflora incarnata suppress PTZ-induced seizures, and ameliorates its associated post-ictal depression, which has been found to be get worsened with the standard antiepileptic drug, diazepam.

Matrix Metalloproteinase-9 Contributes to Kindled Seizure Development in Pentylenetetrazole-Treated Mice by Converting Pro-BDNF to Mature BDNF in the Hippocampus

Recurrent seizure activity has been shown to induce a variety of permanent structural changes in the brain. Matrix metalloproteinases (MMPs) function to promote neuronal plasticity, primarily through cleavage of extracellular matrix proteins. Here, we investigated the role of MMP-9 in the development of pentylenetetrazole (PTZ)-induced kindled seizure in mice. Repeated treatment with PTZ (40 mg/kg) produced kindled seizure, which was accompanied by enhanced MMP-9 activity and expression in the hippocampus. No change in MMP-9 activity was observed in the hippocampi of mice with generalized tonic seizure following single administration of PTZ (60 mg/kg). MMP-9 colocalized with the neuronal marker NeuN and the glial marker GFAP in the dentate gyrus of the kindled mouse hippocampus. Coadministration of diazepam or MK-801 with PTZ inhibited the development of kindling and the increased MMP-9 levels in the hippocampus. Marked suppression of kindled seizure progression in response to repeated PTZ treatment was observed in MMP-9((-/-)) mice compared with wild-type mice, an observation that was accompanied by decreased hippocampal levels of mature brain-derived neurotrophic factor. Microinjecting the BDNF scavenger TrkB-Fc into the right ventricle before each PTZ treatment significantly suppressed the development of kindling in wild-type mice, whereas no effect was observed in MMP-9((-/-)) mice. On the other hand, bilateral injections of pro-BDNF into the hippocampal dentate gyrus significantly enhanced kindling in wild-type mice but not MMP-9((-/-)) mice. These findings suggest that MMP-9 is involved in the progression of behavioral phenotypes in kindled mice because of conversion of pro-BDNF to mature BDNF in the hippocampus.

PTZ-induced seizures inhibit adenosine deamination in adult zebrafish brain membranes

Adenosine exerts neuromodulatory functions with mostly inhibitory effects, being considered an endogenous anticonvulsant. The hydrolysis of ATP by ectonucleotidases is an important source of adenosine, and adenosine deaminase (ADA) contributes to the regulation of this nucleoside concentration through its deamination. In this study, we tested the effect of pentylenetetrazole (PTZ)-induced seizures on ectonucleotidase and ADA activities in adult zebrafish brain. Our results have demonstrated that PTZ treatments did not alter ectonucleotidase and ADA activities in membranes and soluble fraction, respectively. However, ecto-ADA activity was significantly decreased in brain membranes of animals exposed to 5mM and 15mM PTZ treatments (22.4% and 29.5%, respectively) when compared to the control group. Semiquantitative RT-PCR analysis did not show significant changes after the PTZ exposure on ADA gene expression. The decreased adenosine deamination observed in this study suggests a modulation of extracellular adenosine levels during PTZ-induced seizures in zebrafish.

Anticonvulsant and antioxidant actions of trimetazidine in pentylenetetrazole-induced kindling model in mice

The present study was carried out to investigate the effect of trimetazidine on the course of pentylenetetrazole (PTZ)-induced chemical kindling and oxidative stress markers in PTZ-kindled mice. Kindling was induced by repeated injections of a subconvulsive dose of PTZ (30mg⁄kg, i.p.) on alternate days for 5weeks or until stage 4 of the seizure score was evoked on three consecutive administrations. Trimetazidine was administered daily in three doses (5, 10 and 20mg/kg) per orally (p.o.) along with alternate-day PTZ. Following PTZ kindling, oxidative stress parameters, i.e. levels of malondialdehyde (MDA) and reduced glutathione (GSH), were assessed in isolated homogenized whole brain tissue. The results showed that PTZ treatment progressively increased the seizure score in control mice. Biochemical analysis revealed a significant increase in MDA levels and decreased GSH levels in the brain homogenate of PTZ-kindled mice. Daily treatment with trimetazidine in doses of 10 and 20mg/kg significantly decreased the PTZ-induced seizure score. However, a low dose of trimetazidine (5mg/kg) failed to improve the seizure score. Pretreatment of trimetazidine in all doses showed an ameliorating effect on biochemical alteration induced by PTZ treatment. The results of the present study indicate the potential anticonvulsant activity of trimetazidine against PTZ-induced kindling in mice.