Caspase-1 inhibitor CZL80 protects against acute seizures via amplifying the inhibitory neural transmission.

Current anti-seizure medications (ASDs) primarily target ion channels or neurotransmissions; however, their practicability is limited by unwanted side-effects and pharmacoresistance. Cumulative evidence has proposed pro-inflammatory caspase-1 as a potential target for developing ASDs. In this study, we showed that the small-molecular caspase-1 inhibitor CZL80 can prevent seizures in various models including the maximal electroshock (MES), the pentylenetetrazol (PTZ), and the amygdaloid kindled models. Specifically, we discovered that CZL80 prevented death, reduced the duration of generalized seizures, and increased the threshold of generalized seizures in a dose-dependent manner in the MES model. In the PTZ model, CZL80 decreased the seizure stages, prolonged the latency to stage 4 seizures, and decreased the death rate. And in amygdaloid kindled rats, CZL80 inhibited the seizure stages, shortened the durations of both generalized seizures and after-discharges. And the anti-seizure efficacy of CZL80 was diminished in caspase-1 knockout mice. In vitro electrophysiology recordings revealed that CZL80 was able to decreased the excitability of glutamatergic pyramidal neurons, as denoted by reducing the spontaneous neuronal firings and increasing the rheobase injected currents to elicit action potentials. Furthermore, CZL80 was able to increase the amplitudes of inhibitory post-synaptic currents (IPSC), while the excitatory post-synaptic currents (EPSC) were not influenced. Lastly, daily administration of CZL80 for 3 weeks did not influence the normal locomotor functions in mice. In sum, our results highlighted CZL80 as a potential anti-seizure therapy with therapeutic significance.

Electrophysiologic and anti-inflammatorial effects of cyclooxygenase inhibition in epileptiform activity.

The aim of our study is to investigate the electrophysiological and anti-inflammatory effects of diclofenac potassium on epileptiform activity, which is the liquid form of diclofenac, and frequently used clinically for inflammatory process by inhibiting cyclooxygenase enzyme (COX). Wistar rats aged 2-4 months were divided into Epilepsy, Diazepam, Diclofenac potassium, and Diazepam+diclofenac potassium groups. Diazepam and diclofenac potassium were administered intraperitoneally 30 min after the epileptiform activity was created with penicillin injected intracortically under anesthesia. After the electrophysiological recording was taken in the cortex for 125 min, interleukin-1ß (IL-1ß), interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α) were evaluated by the ELISA in the serums. No change was observed between the groups in serum IL-1ß, IL-6, and TNF-α values. It was observed that the co-administration of diclofenac potassium and diazepam at 51-55, 56-60, 61-65, 111-115, and 116-120 min was more effective in reducing spike amplitude than diclofenac potassium alone (p < 0.05). Single-dose diclofenac potassium did not have an anti-inflammatory effect in epileptiform activity but both diazepam and diclofenac potassium reduced the epileptiform activity.

Pediatric Cerebral Sinovenous Thrombosis and Risk for Epilepsy.

BACKGROUND: Cerebral sinovenous thrombosis (CSVT) is a rare form of pediatric stroke with significant morbidity. We determined cumulative incidence and predictors of acute seizures, remote seizures, and epilepsy after pediatric CSVT. METHODS: Retrospective analysis of 131 neonates and children with neuroimaging-confirmed CSVT enrolled between 2008 and 2020 from a single-center prospective consecutive cohort. Acute seizures occurred within 7 days of CSVT. Remote seizures occurred >7 days after CSVT. Epilepsy was defined as 2 or more remote seizures at least 24 hours apart. Survival methods determined the incidence of and risk factors for remote seizures and epilepsy. RESULTS: Acute seizures occurred in 14/33 neonates (42%) and 19/98 children (19%). Among children, hemorrhage predicted acute seizures (OR 6.6, 95% CI 1.9 to 22.4, P = 0.003). Remote seizures occurred in six neonates; five developed epilepsy. Remote seizures occurred in 14 children; 10 developed epilepsy. In neonates, 1- and 3-year epilepsy-free survival were 86% (95% CI 62% to 95%) and 66% (95% CI 32% to 87%). One- and 3-year epilepsy-free survival in children were 88% (95% CI 76% to 92%) and 84% (95% CI 59% to 86%). In multivariable analysis for children, acute seizures predicted epilepsy (HR 3.8, 95% CI 1.1-13.3, P = 0.039). In both cohorts, Pediatric Stroke Outcome Measure scores at last follow-up were worse in those with epilepsy compared to those without. CONCLUSIONS: Acute seizures occurred in approximately one quarter of our cohort and are an epilepsy risk factor in children with CSVT. Neonates and children with epilepsy had worse outcomes than those without.

Chinese families' knowledge, attitudes, and practices regarding seizure management for children with epilepsy: a mixed-methods study.

Objective: This study aimed to examine Chinese families' knowledge, attitudes, and practices regarding the management of acute seizures (AS) that occur outside the hospital in children with epilepsy (CWE) and factors that influence AS. Design: A mixed-methods sequential explanatory study was conducted, which was integrated at the design and methods levels. In phase 1, a questionnaire was developed for this study, and a family functioning assessment was administered from Nov 2021 to Apr 2022. Multivariate logistic regression was used to analyze the knowledge, attitudes, and practices (KAP) and factors that influence AS. In phase 2, family caregivers (FCGs) were recruited from Jul to Aug 2022 to participate in a qualitative exploration, using semi-structured interviews and a combination of inductive and deductive methods. Setting: The setting was five children's specialty hospitals in different regions of China. Participants: The participants were FCGs of CWE. A total of 645 participants were included in the quantitative phase, and 15 FCGs (eight parents, five grandparents, and two others) were recruited for the qualitative phase. Results: The FCGs' average total KAP score for AS management was 66.23 ± 15.12, with 45.42% of FCGs having a low level. Univariate and multivariate regression analyses showed that demographic factors, disease characteristics, and family function significantly predicted family management of AS. The three most salient themes and eight sub-themes from phase 2 were explored. The quantitative and qualitative databases were analyzed separately and combined through integration, and a conceptual model was constructed based on the individual and family self-management theory (IFSMT); the model consisted of context, knowledge, self-regulation, and promotion factors. Conclusion: Chinese families have a positive attitude toward the management of out-of-hospital AS in CWE, but lack practice and related knowledge. AS management for CWE families was associated with the demographic characteristics of FCGs, epilepsy, and family characteristics. The research findings expand the existing application requirements of an Acute Seizure Action Plan and patient safety. Our results also indicate a pressing need for localized development of AS emergency medicine in family medicine, the establishment of auxiliary information systems, the utilization of caregivers' positive psychological resources, and improvements in family function for intergenerational care.

In Vivo and In Vitro Characterization of Close Analogs of Compound KA-11, a New Antiseizure Drug Candidate.

Epilepsy is a neurological disorder involving a number of disease syndromes with a complex etiology. A properly matched antiseizure drug (ASD) gives remission in up to 70% of patients. Nevertheless, there is still a group of about 30% of patients suffering from drug-resistant epilepsy. Consequently, the development of new more effective and/or safer ASDs is still an unmet clinical need. Thus, our current studies were focused on the structural optimization/modifications of one of the leading compounds, KA-11, aiming at the improvement of its antiseizure activity. As a result, we designed and synthesized two close analogs with highly pronounced drug-like physicochemical properties according to in silico predictions, namely KA-228 and KA-232, which were subsequently tested in a panel of animal seizure models, i.e., MES, 6 Hz (32 mA), scPTZ and ivPTZ. Among these compounds, KA-232, which was designed as a water-soluble salt, was distinctly more effective than KA-228 and assured similar antiseizure protection as its chemical prototype KA-11. With the aim of a more detailed characterization of both new molecules, in vitro binding tests were performed to evaluate the potential mechanisms of action. Furthermore, KA-232 was also evaluated in several ADME-Tox studies, and the results obtained strongly supported its drug-like potential. The proposed chemical modification of KA-11 enabled the identification of new pharmacologically active chemotypes, particularly water-soluble KA-232, which, despite the lack of better efficacy than the leading compound, may be used as a chemical prototype for the development of new ASDs, as well as substances potentially active in other neurological or neurodegenerative conditions.

Can hyperoxic stress cause susceptibility to acute seizure in the neonatal period?: a rat study.

Objective: Preterm neonates encounter hyperoxia relatively early, and are more exposed to hyperoxic stress due to their insufficient antioxidant defense mechanisms. This study was planned around the hypothesis that this hyperoxic effect may cause a disposition to future acute seizures. Methods: This study was composed of two main groups Hyperoxy and Control (Room air with normal O2 levels) Groups. Group 1 - hyperoxia (Study): The experimental group consisted of premature newborn rats exposed to hyperoxia with their dams from birth to postnatal day 5. Group 2 - room air (Control): The group was not exposed to hyperoxia and housed the same room air and temperature as their dams. Female, Acute Epilepsy Female, Male, Acute Epilepsy Male, and a total of eight subgroups were formed in both the control and hyperoxia groups. When the rats were two months old, intracranial electrodes were attached to obtain electrocorticography (ECoG) recordings. Pre-model recordings were taken, after which an acute pentylenetetrazole (PTZ) model of absence seizure was induced by the intraperitoneal administration of PTZ at 50 mg/kg. ECoG records were examined using the PowerLab system for 180 min. Spike wave number and duration, Spike wave frequency and amplitude data were evaluated.Results: Seven female and three male rats were exposed to hyperoxia, and a control group of five female and three male rats were included in the study. The median interquartile range for spike wave latency in the hyperoxia and control groups were 1112 (644-1545) and 654 (408-1152), frequency 4476 (3120-7421) and 3934 (2264-4704), and amplitude data 0.68 (0.59-0.79) and 0.52 (0.37-0.67), respectively. Although a difference was observed in median values capable of constituting susceptibility to epilepsy, the difference was not statistically significant (p > 0.05). In terms of gender, spike-wave counts were significantly higher in female rats (p < 0.05). Females exposed to hyperoxia were more susceptible to epilepsy than both males and females in the control group (p < 0.05).Conclusion: Exposure to hyperoxia in the first days of life of premature neonates due to their susceptibility to oxidative stress and insufficient antioxidant mechanisms, can cause a disposition to acute seizures. As a result, females exposed to hyperoxia during the neonatal period may be prone to epilepsy in maturity.

Intravenous Brivaracetam in the Management of Acute Seizures in the Hospital Setting: A Scoping Review.

BACKGROUND: Clinical considerations for drug treatment of acute seizures involve variables such as safety, tolerability, drug-drug interactions, dosage, route of administration, and alterations in pharmacokinetics because of critical illness. Therapy options that are easily and quickly administered without dilution, well tolerated, and effective are needed for the treatment of acute seizures. The objective of this review is to focus on the clinical considerations relating to the use of intravenous brivaracetam (IV BRV) for the treatment of acute seizures in the hospital, focusing on critically ill patients. METHODS: This was a scoping literature review of PubMed from inception to April 13, 2021, and search of the American Academy of Neurology (AAN) 2021 Annual Meeting website for English language publications/conference abstracts reporting the results of IV BRV use in hospitalized patients, particularly in the critical care setting. Outcomes of interest relating to the clinical pharmacology, safety, tolerability, efficacy, and effectiveness of IV BRV were reviewed and are discussed. RESULTS: Twelve studies were included for analysis. One study showed that plasma concentrations of IV BRV 15 min after the first dose were similar between patients receiving IV BRV as bolus or infusion. IV BRV was generally well tolerated in patients with acute seizures in the hospital setting, with a low incidence of individual TEAEs classified as behavioral disorders. IV BRV demonstrated efficacy and effectiveness and had a rapid onset, with clinical and electrophysiological improvement in seizures observed within minutes. Although outside of the approved label, findings from several studies suggest that IV BRV reduces seizures and is generally well tolerated in patients with status epilepticus. CONCLUSIONS: IV BRV shows effectiveness, and is generally well tolerated in the management of acute seizures in hospitalized patients where rapid administration is needed, representing a clinically relevant antiseizure medication for potential use in the critical care setting.

Intranasal midazolam versus intravenous/rectal benzodiazepines for acute seizure control in children: A systematic review and meta-analysis.

BACKGROUND: Acute seizure activity might cause complications including bodily harm, progression to status epilepticus, and poor quality of life in children. The introduction of a venous line may be difficult in children with seizures which would delay the initiation of treatment. Rectal drug administration can be socially awkward for patients and providers. Intranasal (IN) midazolam offers a valuable substitute that is easier and faster to administer. OBJECTIVE: To assess the efficacy, safety, and acceptability of intranasal midazolam in children with acute seizure when compared to conventional IV or rectal benzodiazepine (BDZ). METHODS: PubMed, google scholar, websites clinicaltrials.gov and the WHO-international clinical trials registry platform, were searched. Randomized controlled/prospective randomized trials comparing IN midazolam against IV/rectal BDZ in the treatment of acute seizures in pediatric patients were included in the meta-analysis. RESULTS: Data of 10 studies were quantitatively analyzed. Intranasal midazolam (n = 169) when compared to IV/rectal BDZ (n = 161) has a shorter interval between hospital arrival and seizure cessation {(mean difference = -3.51; 95% CI [-6.84, -0.18]) P = 0.04}. Regarding time to seizure cessation after midazolam (n = 326) or BDZ (n = 322) administration, there is no significant difference between the two groups {(mean difference = -0.03; 95% CI [-1.30, 1.25]), P = 0.97} and both are equally effective for controlling acute seizures (odds ratio = 1.06; 95% CI [0.43, 2.63]; n = 737). CONCLUSION: In children with acute seizures, IN midazolam is equally effective in aborting seizure and decreases the total time from hospital arrival and cessation of seizures, eventually leading to faster cessation of seizure as compared to IV/rectal BDZ.

Mapping region-specific seizure-like patterns in the in vitro isolated guinea pig brain.

Specific neurophysiological seizure patterns in patients with focal epilepsy depend on cerebral location and the underlying neuropathology. Location-specific patterns have been also reported in experimental models. Two focal seizure patterns, named p-type and l-type, typical of neocortical and mesial temporal regions were identified in both patients explored with intracerebral EEG and in animal models. These two patterns were recorded in the olfactory regions and in the entorhinal cortex after either 4AP or BMI administration. Here we mapped epileptiform activities in other cortices to verify the existence of specific epileptiform patterns. Field potentials were simultaneously recorded at multiple locations in olfactory, limbic and neocortical regions of the isolated guinea pig brain after arterial administration of either 4AP or BMI. Most neocortical areas did not generate new distinctive focal seizure-like event (SLE), beside the p-type and l-type patterns. Spiking activity was typically recorded after BMI in all new analyzed regions, whereas SLEs were commonly observed during 4AP perfusion. We confirmed the presence of reproducible region-specific epileptiform patterns in all explored cortical areas and demonstrated that strongly inter-connected areas generate similar SLEs. Our study suggests that p- and l-type SLE represent the most common focal seizure patterns during acute manipulations with pro-epileptic compounds.

Clinical pharmacokinetic and pharmacodynamic profile of midazolam nasal spray.

The benzodiazepine midazolam (MDZ) is commonly used as first-line treatment in patients with acute seizures. This review summarizes the pharmacokinetic (PK) and pharmacodynamic (PD) characteristics of MDZ nasal spray (MDZ-NS), which can be administered by non-health care providers in the outpatient, ambulatory setting. Intranasal administration leads to rapid (tmax 9.0-21.5 min), consistent, and extensive absorption of MDZ, with fast distribution to the central nervous system (CNS), as demonstrated by the onset of sedation within 10 min after administration and the occurrence of peak psychomotor impairment at approximately 17-120 min after administration. Rapid plasma clearance of MDZ and its active metabolite 1-OH-MDZ (t½ 3.6-8.1 h) results in a return to baseline alertness and psychomotor functionality by approximately 240 min post dose. The lack of first-pass metabolism reduces the potential for drug-drug interactions compared with oral dosing. Age (≥ 12 years), sex, race, body weight, body mass index, normal to moderately impaired renal function, and concomitant administration of cytochrome P450 (CYP)3A-inducing drugs are not considered important factors for MDZ-NS dosing. However, coadministration of MDZ-NS with moderate or strong CYP3A4 inhibitors should be avoided, and MDZ-NS should be used with caution when coadministered with mild CYP3A4 inhibitors, as these may result in prolonged MDZ effects owing to a decrease in plasma clearance. Taken together, the PK and PD properties of MDZ-NS, with a short tmax that translates into rapid CNS PD effects of sedation and psychomotor impairment, demonstrate rapid CNS penetration and onset of action, supporting its use for acute treatment of seizure clusters.

Update on Anticonvulsant Therapy in the Emergent Small Animal Patient.

Seizures are common in veterinary patients and control is critical to the overall patient health. The benzodiazepine class of drugs (diazepam, midazolam, and lorazepam) often are the drug class of choice; however, levetiracetam and propofol also have been gaining favor as anticonvulsant drugs for acute seizure management. After cessation of seizures, practitioners then can discuss long-term seizure control on a case-by-case basis with clients.

Randomized open-label trial of intravenous brivaracetam versus lorazepam for acute treatment of increased seizure activity.

OBJECTIVE: The objective of the present trial was to assess efficacy and safety of intravenous (IV) brivaracetam (BRV) vs. lorazepam (LZP) in patients with epilepsy undergoing evaluation in an epilepsy monitoring unit (EMU) who experienced seizures requiring acute treatment. METHODS: This was a phase 2, open-label, randomized, active-control, proof-of-concept trial (EP0087; NCT03021018). Patients (18-70 years) admitted to EMU were randomized 1:1:1 to single-dose bolus IV LZP (dose per investigator's practice), IV BRV 100 mg, or IV BRV 200 mg. Trial medication had to be administered within 30 min of qualifying seizure. Primary efficacy outcome was time to next seizure (clinical observation with electroencephalogram [EEG] confirmation) or to rescue medication use within 12 h of trial medication administration. Secondary outcomes included seizure freedom and rescue medication use within 12 h of trial medication administration. Safety and tolerability outcomes included treatment-emergent adverse events (TEAEs). RESULTS: Overall, 46 patients were randomized, and 45 received trial medication for a qualifying seizure. Patients in the LZP arm had doses from 1 to 4 mg (median: 1 mg). Eleven of 45 patients had a seizure within 12 h of trial medication administration (LZP 5/15 [median time to next seizure: 5.55 h], BRV 100 mg 3/15 [5.97 h], BRV 200 mg 3/15 [3.60 h]). No patients received additional rescue medication to control their qualifying seizure. Most patients were seizure-free over 12 h (LZP 9/15 [60.0%], BRV 100 mg 12/15 [80.0%], BRV 200 mg 12/15 [80.0%]). Rescue medication use within 12 h was numerically higher for LZP (6/15 [40.0%]) vs. BRV 100 mg (1/15 [6.7%]) and vs. BRV 200 mg (2/15 [13.3%]). Treatment-emergent adverse events were reported by 5/16 (31.3%), 6/15 (40.0%), and 3/15 (20.0%) of LZP, BRV 100 mg, and BRV 200 mg patients; one LZP patient had a serious TEAE (seizure cluster). Most common TEAEs (≥10% of patients) were sedation and somnolence with LZP, and dizziness, headache, and nausea with BRV. SIGNIFICANCE: Intravenous LZP, IV BRV 100 mg, and IV BRV 200 mg showed similar efficacy in controlling acute seizure activity in the EMU. Treatment-emergent adverse events were as expected for each medication. Although this trial should be interpreted with caution because of small patient numbers, it suggests a possible role of BRV in the acute treatment of increased seizure activity.

Enhanced thalamo-hippocampal synchronization during focal limbic seizures.

OBJECTIVE: The key factors that promote the termination of focal seizures have not been fully clarified. The buildup of neuronal synchronization during seizures has been proposed as one of the possible activity-dependent, self-limiting mechanisms. We investigate if increased thalamo-cortical coupling contributes to enhance synchronization during the late phase of focal seizure-like events (SLEs) generated in limbic regions. METHODS: Recordings were simultaneously performed in the nucleus reuniens of the thalamus, in the hippocampus and in the entorhinal cortex of the isolated guinea pig brain during focal bicuculline-induced SLEs with low voltage fast activity at onset. RESULTS: Spectral coherence and cross-correlation analysis demonstrated a progressive thalamo-cortical entrainment and synchronization in the generation of bursting activity that characterizes the final part of SLEs. The hippocampus is the first activated structure at the beginning of SLE bursting phase and thalamo-hippocampal synchronization is progressively enhanced as SLE develops. The thalamus takes the lead in generating the bursting discharge as SLE end approaches. SIGNIFICANCE: As suggested by clinical studies performed during pre-surgical intracranial monitoring, our data confirm a role of the midline thalamus in leading the synchronous bursting activity at the end of focal seizures in the mesial temporal regions.

Evaluation of the Anticonvulsant Effect of Brilliant Blue G, a Selective P2X7 Receptor Antagonist, in the iv PTZ-, Maximal Electroshock-, and 6 Hz-Induced Seizure Tests in Mice.

Epilepsy is one of the most common neurological disorders which is diagnosed in around 65 million people worldwide. Clinically available antiepileptic drugs fail to control epileptic activity in about 30% of patients and they are merely symptomatic treatments and cannot cure or prevent epilepsy. There remains a need for searching new therapeutic strategies for epileptic disorders. The P2X7 receptor has been recently investigated as a new target in epilepsy treatment. Preclinical studies revealed that P2X7 receptor antagonists have anticonvulsant properties in some models of epilepsy. We aimed to investigate whether P2X7 receptor antagonist-brilliant blue G (BBG)-is able to change seizure threshold in three acute seizure models in mice, i.e., in the intravenous pentylenetetrazole seizure threshold, maximal electroshock seizure threshold and 6 Hz psychomotor seizure threshold tests. BBG was administered acutely (50-200 mg/kg, 30 min before the tests) and sub-chronically (25-100 mg/kg, once daily for seven consecutive days). Moreover, the chimney and grip strength tests were used to estimate the influence of BBG on the motor coordination and muscular strength in mice, respectively. Our results revealed only a week anticonvulsant potential of the studied P2X7 receptor antagonist because it showed anticonvulsant action only in the 6 Hz seizure test, both after acute and sub-chronic administration. BBG did not significantly influence seizure thresholds in the remaining tests. Motor coordination and muscular strength were not affected by the studied P2X7 receptor antagonist. In summary, BBG does not possess any remarkable anticonvulsant potential in acute seizure models in mice.

Providing teachers with education on epilepsy increased their willingness to handle acute seizures in children from one to 10 years of age.

AIM: In Germany, preschool teachers supervise children up to six years of age and are also responsible for supervising older pupils after school. This study explored the impact of a teaching session on epilepsy for teachers in charge of children from 1 to 10 years of age. METHODS: We evaluated the benefit of a teaching session offered to all preschool teachers in Leipzig, Germany, in 2014-2015, by asking them to complete the same questionnaire 12-24 months pre-intervention, and 12 months postintervention. RESULTS: Both questionnaires were completed by 123 teachers. The number of teachers who felt they were prepared to handle an acute seizure rose from 36 (29%) pre-intervention to 65 (53%) post-intervention (p < 0.001) and their willingness to administer a prescribed rescue medication rose from 66 (54%) to 93 (76%, p < 0.001). The session also increased the number of teachers who were prepared to take children with epilepsy on excursions under any circumstance from 38 (31%) to 52 (42%, p < 0.05). In addition, the number of teachers who would place a solid object in the child's mouth during an attack fell from 16 (13%) to seven (6%) (p < 0.05). CONCLUSION: Providing a teaching session on epilepsy increased the teachers' knowledge and willingness to act and reduced obsolete, counterproductive measures.

Transplantation of inhibitory precursor cells from medial ganglionic eminence produces distinct responses in two different models of acute seizure induction.

Medial ganglionic eminence (MGE) is one of the sources of inhibitory interneurons during development. Following transplantation in postnatal developing brain, MGE cells can increase local inhibition suggesting a possible protection to GABAergic dysfunction in brain disorders, such as epilepsy. Since it has been shown that MGE-derived cells harvested as neurospheres are able to suppress seizures, it might be important to investigate whether these protective effects would change in different seizure models. Here, we used pentylenetetrazole-(PTZ) and maximal electroshock (MES)-induced seizure models to test whether the transplantation of MGE cells would increase the threshold to trigger acute seizures. When transplanted into the neocortex (layers 3-4) of neonatal mice (postnatal days 3-4), MGE cells were able to survive and were mainly found in piriform cortex, fimbria, and ventricular wall regions. Additionally, the number of GFP+ cells found in the brains of mice induced with PTZ and MES differed significantly and suggests proliferation and larger survival rate of MGE-transplanted cells after PTZ, but not MES-induced seizures. Following transplantation, there was a reduction in the number of animals presenting mild and severe seizures induced by PTZ. Furthermore, MGE-cell transplantation was able to increase threshold to seizures induced by PTZ, but was not able to prevent seizure spread induced by MES.

Comparison between the effects of quercetin on seizure threshold in acute and chronic seizure models.

Flavonoids are important constituents of food and beverages, and several studies have shown that they have neuroactive properties. Many of these compounds are ligands for γ-aminobutyric acid type A receptors in the central nervous system. This study aimed to investigate the anticonvulsant effects of quercetin (3,3',4',5,7-pentahydroxyflavone), which is a flavonoid found in plants, in rats treated with pentylenetetrazole in acute and chronic seizure models. Single intraperitoneal administration of quercetin did not show anticonvulsive effects against acute seizure. Similarly, multiple oral pretreatment with quercetin did not have protective effects against acute seizure. However, multiple intraperitoneal administration of quercetin (25 and 50 mg/kg) significantly increased time to death compared with the control (p < 0.001). However, quercetin pretreatment had no significant effects on the pattern of convulsion development during all periods of kindling. But on the test day, quercetin (100 mg/kg) could significantly increase generalized tonic-clonic seizure onset (GTCS) and decrease GTCS duration compared with the control (p < 0.01, p < 0.05). We conclude that quercetin has a narrow therapeutic dose range for anticonvulsant activities in vivo, and it has different effects on the seizure threshold. The different effects of quercetin on seizure threshold may occur through several mechanisms.

Effects of an acute seizure on associative learning and memory.

Past studies have demonstrated that inducing several seizures or continuous seizures in neonatal or adult rats results in impairments in learning and memory. The impact of a single acute seizure on learning and memory has not been investigated in mice. In this study, we exposed adult 129SvEvTac mice to the inhalant flurothyl until a behavioral seizure was induced. Our study consisted of 4 experiments where we examined the effect of one seizure before or after delay fear conditioning. We also included a separate cohort of animals that was tested in the open field after a seizure to rule out changes in locomotor activity influencing the results of memory tests. Mice that had experienced a single seizure 1h, but not 6h, prior to training showed a significant impairment in associative conditioning to the conditioned stimulus when compared with controls 24h later. There were no differences in freezing one day later for animals that experienced a single seizure 1h after associative learning. We also found that an acute seizure reduced activity levels in an open-field test 2h but not 24h later. These findings suggest that an acute seizure occurring immediately before learning can have an effect on the recall of events occurring shortly after that seizure. In contrast, an acute seizure occurring shortly after learning appears to have little or no effect on long-term memory. These findings have implications for understanding the acute effects of seizures on the acquisition of new knowledge.

Synchronous inhibitory potentials precede seizure-like events in acute models of focal limbic seizures.

Interictal spikes in models of focal seizures and epilepsies are sustained by the synchronous activation of glutamatergic and GABAergic networks. The nature of population spikes associated with seizure initiation (pre-ictal spikes; PSs) is still undetermined. We analyzed the networks involved in the generation of both interictal and PSs in acute models of limbic cortex ictogenesis induced by pharmacological manipulations. Simultaneous extracellular and intracellular recordings from both principal cells and interneurons were performed in the medial entorhinal cortex of the in vitro isolated guinea pig brain during focal interictal and ictal discharges induced in the limbic network by intracortical and brief arterial infusions of either bicuculline methiodide (BMI) or 4-aminopyridine (4AP). Local application of BMI in the entorhinal cortex did not induce seizure-like events (SLEs), but did generate periodic interictal spikes sensitive to the glutamatergic non-NMDA receptor antagonist DNQX. Unlike local applications, arterial perfusion of either BMI or 4AP induced focal limbic SLEs. PSs just ahead of SLE were associated with hyperpolarizing potentials coupled with a complete blockade of firing in principal cells and burst discharges in putative interneurons. Interictal population spikes recorded from principal neurons between two SLEs correlated with a depolarizing potential. We demonstrate in two models of acute limbic SLE that PS events are different from interictal spikes and are sustained by synchronous activation of inhibitory networks. Our findings support a prominent role of synchronous network inhibition in the initiation of a focal seizure.