Postictal Depression Research Articles

A study on the anticonvulsant activity of Withania somnifera (Dunal) in albino rats

Background: The present study is an investigation of antiepileptic activity of Withania somnifera (Ashwagandha) is a well-known plant which is being used in tuberculosis, emaciation, sterility, and it has immunomodulatory, anabolic, anti-inflammatory, and antianxiety activities. Aims and Objectives: To find the efficacy of the alcoholic extract of W. somnifera (Dunal) in preventing experimentally-induced seizures. Materials and Methods: The alcoholic extract of W. somnifera was subjected to pilot study and then screened for anticonvulsant activity on maximal electroshock (MES) and pentylenetetrazole (PTZ)-induced seizures models in albino Wistar rats. Animals were treated with W. somnifera at doses of 100 mg/kg, 200 mg/kg, and 300 mg/kg body weight and compared the results with control and standard. Results: Study results showed that W. somnifera extract at the dose of 300 mg/kg body weight when compared to control group highly significant (P < 0.01) reduction of hindlimb tonic extension and postictal depression in MES. PTZ-induced seizures showed significantly reduced mean duration of hindlimb tonic flexion, hindlimb tonic extension, clonus, and stupor and there was no postictal depression. Conclusions: The alcoholic extract of W. somnifera (Dunal) has shown a significant anticonvulsant effect at the dose of 300 mg/kg body weight, both in MES method and PTZ method and has given higher protection rate against pentylenetetrazol seizure than MES.

Alcohol withdrawal in epileptic rats - Effects on postictal depression, respiration, and death.

Patients with epilepsy are at risk of sudden unexpected death in epilepsy (SUDEP). The most common series of events in witnessed cases of SUDEP is a generalized convulsive seizure followed by terminal apnea. Risk factors for SUDEP include prolonged postictal depression (PID), as well as alcohol abuse. The present study examined these issues in a genetic epilepsy model that exhibits generalized convulsive audiogenic seizures (AGSz) but rarely exhibits seizure-induced death, the genetically epilepsy-prone rats (GEPR-9s). We evaluated the effect of ethanol withdrawal (ETX) in GEPR-9s on respiration patterns, duration of PID, and the incidence of seizure-induced death. Audiogenic seizures were induced in GEPR-9s and in normal Sprague-Dawley rats, which were subjected to a 4-day binge ethanol protocol, 18-24h after the last ethanol dose. Following the tonic seizures, all GEPR-9s exhibited PID, characterized by loss of the righting reflex and respiratory distress (RD), which were absent during ETX seizures in the normal rats. During ETX, GEPR-9s exhibited significant increases in the duration of PID and RD, compared with vehicle-treated GEPR-9s. A significant increase in the incidence of death following seizure in GEPR-9s subjected to ETX was observed, compared with that in vehicle-treated GEPR-9s and normal rats subjected to ETX. Death in GEPR-9s was preceded by prolonged seizures because, in part, of the emergence of post-tonic generalized clonus. These results indicate that ETX induced significant increases in the duration of PID and RD, which contributed to the greater incidence of mortality in GEPR-9s compared with that in vehicle-treated GEPR-9s and normal rats. These experiments observed an elevated risk of sudden death associated with alcohol withdrawal in a genetic epilepsy model that had previously been identified as a risk factor in human SUDEP.

Clinique et neurobiologie des psychoses post-ictales

Psychosis in epilepsy can be categorized in relation to seizures in two main categories: interictal psychosis and postictal psychosis. Postictal psychosis (PIP) is a specific syndrome in relation to seizure activity: a clear temporal relation exists between the psychotic state of sudden onset and a precipitating bout of complex partial or generalized seizures. However, this very specific syndrome is not included as such within the DSM-5, and PIP belongs to the category “Psychotic disorder due to another medical condition”. Diagnostic criteria are: (1) episode of psychosis within 1 week after a seizure(s); (2) psychosis lasts more than 15hours and less than 2 months; (3) delusions, hallucinations in clear consciousness, bizarre, or disorganized behavior, formal thought disorder, or affective changes; and (4) no evidence AED toxicity, non-convulsive status epilepticus, recent head trauma, alcohol, or drug intoxication or withdrawal, prior chronic psychotic disorder. The presence of a lucid interval between the last seizure and start of changes rules out a simple postictal delirium. The outcome is characterized by a remission of the psychotic symptoms over several days (mean: 1 week), with or without any treatment. Prepsychotic EEG abnormalities persist during the psychosis. Risk factors for PIP include: long standing localization-related epilepsy, extratemporal onset, bilateral epileptiform activity, secondary generalization, slowing of the EEG background activity and personal or family history of psychiatric disorders. Brain MRI frequently shows structural abnormalities. Several functional neuroimaging studies have shown hyperperfusion in various cerebral regions during PIP, suggesting an excessive activation of particular structures of the brain rather than a postictal depression of cerebral activity. Implanted electrode studies have shown that the EEG correlate of psychotic symptoms differs from the ictal EEG correlate of epileptic seizures. The value of antipsychotic treatment in PIP requires further studies. Despite their role in symptomatic relief, there is no clear effect of neuroleptics on duration or prognosis of PIP. Different combinations of pharmaceutical interventions can be tried on a case by case basis: (1) oral administration of benzodiazepine; (2) combined oral administration of benzodiazepine and atypical neuroleptics; (3) intramuscular administration of dopamine-blockers for rapid tranquilization of violent or agitated patients. The notion that neuroleptic drugs lower the seizure threshold has no clinical significance: there is no evidence that antipsychotic drugs increase seizure frequency in epileptic patients treated with antiepileptic drugs.

Inhibition of adenosine metabolism induces changes in post-ictal depression, respiration, and mortality in genetically epilepsy prone rats

A major cause of mortality in epilepsy patients is sudden unexpected death in epilepsy (SUDEP). Post-ictal respiratory dysfunction following generalized convulsive seizures is most commonly observed in witnessed cases of human SUDEP. DBA mouse models of SUDEP are induced by audiogenic seizures (AGSz) and show high incidences of seizure-induced death due to respiratory depression. The relatively low incidence of human SUDEP suggests that it may be useful to examine seizure-associated death in an AGSz model that rarely exhibits sudden death, such as genetically epilepsy-prone rats (GEPR-9s). Adenosine is released extensively during seizures and depresses respiration, which may contribute to seizure-induced death. The present study examined the effects of inhibiting adenosine metabolism on the durations of post-ictal depression (PID) and respiratory distress (RD), changes in blood oxygen saturation (% SpO2), and the incidence of post-seizure mortality in GEPR-9s. Systemic administration of adenosine metabolism inhibitors, erythro-9-(2-hydroxy-3-nonyl) adenine (EHNA, 30mg/kg) with 5-Iodotubericidin (5-ITU, 3mg/kg) in GEPR-9s resulted in significant changes in the duration of AGSz-induced PID as compared to vehicle in both genders. These agents also significantly increased the duration of post-seizure RD and significantly decreased the mean% SpO2 after AGSz, as compared to vehicle but only in females. Subsequently, we observed that the incidences of death in both genders 12–48h post-seizure were significantly greater in drug vs. vehicle treatment. The incidence of death in females was also significantly higher than in males, which is consistent with the elevated seizure sensitivity of female GEPR-9s developmentally. These results support a potentially important role of elevated adenosine levels following generalized seizures in the increased incidence of death in GEPR-9s induced by adenosine metabolism inhibitors. These findings may also be relevant to human SUDEP, in light of the elevated adenosine levels that occur post-ictally in humans and its respiratory depressant actions.

Épilepsie : pour une sémiologie neuropsychiatrique de la dépression

The prevalence of psychiatric disorders is significantly higher among patients with epilepsy than the general population. Moreover, the profile of depressive disorder is often atypical in patients with epilepsy. Data from human and animal studies have tended to point towards a bidirectional link in the pathophysiological basis of both epilepsy and depressive syndrome. Depressive symptoms in epilepsy can be divided into those occurring in the peri-ictal period (pre-ictal, ictal and post-ictal), and those occurring in the inter-ictal period. Peri-ictal depressive disorders are particularly associated with temporal lobe epilepsies. These include: (i) peri-ictal dysphoria, (symptoms occur in the 24hour period preceding a seizure); (ii) ictal depression, (symptoms develop during the seizure); (iii) post-ictal depression, (symptoms occur in the 72hours following the seizure). The inter-ictal depressive disorders are not temporally related to seizures. The best characterized of these is “inter-ictal dysphoric disorder”. This includes labile depressive symptoms (depressed mood, anergia, pain, insomnia), labile affective symptoms (panic-like symptoms and anxiety), and supposedly “specific” symptoms (paroxysmal irritability and instable-euphoric moods). Standard psychiatric classification may be inadequate to describe some of the atypical profiles seen in this patient population. Depression in patients with epilepsy is therefore under-diagnosed, and yet contributes to poorer quality of life, epilepsy outcome and risk of suicide. It is recommended that an appropriate screening tool be used to detect signs of major depression, the Neurological Disorders Depression Inventory for Epilepsy (NDDI-E). Clinicians should recognize the characteristics of peri-ictal and inter-ictal depressive syndromes.

EFFECT OF NIMODIPINE AND DICLOFENAC IN EXPERIMENTALLY INDUCED CONVULSIONS USING INH AND ELECTRO CONVULSOMETER IN RATS AND MICE

Aim: The study aims to evaluate the anticonvulsant effect of Nimodipine and combined effect of Nimodipine and Diclofenac in experimentally induced seizures in Rats and Mice taking distilled water as control. Material and methods : Male wistar rats weighing 150-180gms and albino mice of average weight 20-30gms were used.All the preparations were administered intraperitoneally. Convulsions were induced electrically by electroconvulsometer and chemically by INH. The following parameters with electrically induced convulsions are recorded. a)duration of convulsions, b)duration of hind limb extension, c)post ictal depression followed by recovery. With chemically induced convulsions using INH the following parameters are recorded a)onset of convulsions, b)type of convulsions, c)duration of convulsions. Distilled water is used as control. Drugs are given 30 minutes before the electrically and chemically induced convulsions. Effect of Nimodipine and combined effect of Nimodipine and Diclofenac were studied. Results : Nimodipine has reduced the duration of convulsions, hind limb extension, delayed the onset of convulsions and recovery from postictal depression was fast from electric shock. Combined effect of Nimodipine and Diclofenac has an improved effect in duration of convulsions, hind limb extension and recovery when compared with that of Nimodipine alone. Observation: Statistic ANOVA test show significant P value <0.0001 in electrical method and chemical method .The results obtained in this study provide supporting pharmacological evidence of improved efficacy possible potential benefit of combining Nimodipine with Diclofenac in epilepsy. Keywords: Isoniazid(INH), Nimodipine with Diclofenac in epilepsy, anticonvulsant effect, improved effect in duration of convulsions

EEG characterization of audiogenic seizures in the hamster strain GASH:Sal

The study was performed to characterize GASH:SAL audiogenic seizures as true epileptic activity based on electroencephalographic markers acquired with a wireless implanted radiotelemetry system. We analyzed cortical EEG patterns synchronized with video recordings of convulsive behavior of the GASH:Sal hamster following an acoustic stimulus. All GASH:Sal presented archetypal motor symptoms comparable to current animal models of generalized tonic-clonic epilepsy. Seizures consisted of an initial bout of wild running, followed by opisthotonus, tonic-clonic convulsions, tonic limb extension, and terminated in postictal depression. EEG patterns correlated with behavior and displayed phase appropriate spike-wave complexes, low-amplitude desynchronized activity, and high frequency large-amplitude peaks. Our results confirm that electroencephalographic profiles of the audiogenic seizures of the hamster GASH:Sal are parallel to EEG patterns of other animal models of generalized tonic-clonic seizures. Therefore, this animal may serve as an appropriate model for epilepsy research.

Possible Involvement of PPAR-γ in the Anticonvulsant Effect of Aegle marmelos (L.) Correa

Aegle marmelos is well documented for antihyperglycemic effect and PPAR-γ activation has been suggested to be the molecular mechanism of its action. Also, the plant has been used in Ayurveda as a brain tonic and has been postulated to have antidepressant activities. The present study was designed to investigate the anticonvulsant effects of A. marmelos leaf extract (AME) in pentylenetetrazole and maximal electroshock induced convulsions; involvement of PPAR-γ, nitric oxide pathway and effect of chronic AME treatment on post-ictal depression. AME was administered at doses of 50, 100 and 200mgkg(-1) in PTZ and MES model. Severity of convulsions was noted in both the models. Pretreatment with bisphenol A diglycidyl ether (BADGE) was used to study the involvement of PPAR-γ and L-arginine and N-nitro-L-arginine methyl ester hydrochloride (L-NAME) to study the involvement of nitric oxide (NO). Chronic treatment with AME interspersed with sub maximal doses of PTZ (50mgkg(-1)) on every fifth day up to 15days was given to study post-ictal depression using forced swimming and actophotometer. AME showed significant increase in the onset time and decrease in the duration of convulsions in PTZ and MES models dose dependently. In MES a dose of 100mgkg(-1) had effect comparable to phenytoin. Pretreatment with BADGE and L-arginine reversed the protective effect while L-NAME did not alter the protective effect, thereby indicating possible involvement of PPAR-γ and inhibition of NO. Chronic AME treatment ameliorated the post-seizure depression significantly as evidenced by increase in the locomotor activity and decrease in the immobility time.

Prevention of sudden unexpected death in epilepsy: A realistic goal?

Sudden unexpected death in epilepsy (SUDEP) represents one of the most severe consequences of drug-resistant epilepsy, for which no evidence-based prevention is available. Development of effective prevention will depend on the following: (1) better understanding of the pathophysiology of SUDEP to define the most appropriate targets of intervention, and (2) identification of risk factors for SUDEP that would allow for the design of feasible clinical trials to test targeted interventions in high-risk populations. The most important known risk factor is the occurrence and frequency of generalized tonic-clonic seizure (GTCS), a seizure type that triggers the majority of witnessed SUDEP. Therefore, one likely way to prevent SUDEP is to minimize the risk of GTCS with optimal medical management and patient education. However, whether one might prevent SUDEP in patients with refractory epilepsy by using more frequent review of antiepileptic treatment and earlier referral for presurgical evaluation, remains to be seen. Another hypothetical strategy to prevent SUDEP is to reduce the risk of GTCS-induced postictal respiratory distress. This might be achieved by using lattice pillow, providing nocturnal supervision, reinforcing interictal serotoninergic tone, and lowering opiate- or adenosine-induced postictal brainstem depression. Promising interventions can be tested first on surrogate markers, such as postictal hypoxia in epilepsy monitoring units (EMUs), before SUDEP trials can be implemented. EMU safety should also be improved to avoid SUDEP occurrence in that setting. Finally, the development of ambulatory SUDEP prevention devices should be encouraged but raises a number of unsolved issues.

Evidence‐based electroconvulsive therapy

Evidence‐based electroconvulsive therapy

Impact of chronic ethanol intake of rat mothers on the seizure susceptibility of their immature male offspring

The aim of present study was to examine the impact of prenatal ethanol exposure on seizure susceptibility of the offspring. Pregnant Wistar rats were compelled to drink either 10% or 20% ethanol solution, as the only drinking fluid since conception up to the weaning of their offspring at the age of 28 days. Pregnant and nursing rats of the control group drank water. Electrophysiological experiments (repeated electrical stimulation and analysis of cortical afterdischarges duration) were than performed on their immature offspring. Rat pups were tested on postnatal day 18, 25, and 35. Shortening of afterdischarges duration was observed in 18-day-old animals (mothers drank 20% ethanol) when compared with age matched controls and failure of post-ictal depression phenomenon was found in 25- and 35-day-old animals. Our findings signalize that ethanol exposure during pregnancy influences seizure susceptibility by acting on excitatory/inhibitory brain systems and this effect is dose- and age-dependent.

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.

Ionic dynamics mediate spontaneous termination of seizures and postictal depression state.

Epileptic seizures are characterized by periods of recurrent, highly synchronized activity that spontaneously terminates, followed by postictal state when neuronal activity is generally depressed. The mechanisms for spontaneous seizure termination and postictal depression remain poorly understood. Using a realistic computational model, we demonstrate that termination of seizure and postictal depression state may be mediated by dynamics of the intracellular and extracellular ion concentrations. Spontaneous termination was linked to progressive increase of intracellular sodium concentration mediated by activation of sodium channels during highly active epileptic state. In contrast, an increase of intracellular chloride concentration extended seizure duration making possible long-lasting epileptic activity characterized by multiple transitions between tonic and clonic states. After seizure termination, the extracellular potassium was reduced below baseline, resulting in postictal depression. Our study suggests that the coupled dynamics of sodium, potassium, and chloride ions play a critical role in the development and termination of seizures. Findings from this study could help identify novel therapeutics for seizure disorder.

Post-ictal analgesia in genetically epilepsy-prone rats is induced by audiogenic seizures and involves cannabinoid receptors in the periaqueductal gray

Post-ictal depression of consciousness occurs after generalized convulsive seizures, and includes analgesia, lasting for hours after electrically or chemically induced seizures in animals. The brain sites and mechanisms, mediating post-ictal analgesia, are unclear. The ventrolateral periaqueductal gray (PAG) is an important neuronal network site for mediating analgesia and also in generalized seizures, particularly in genetically epilepsy-prone rats (GEPRs). Endocannabinoids are implicated in mediating analgesia in several brain sites, including the PAG, and generalized seizures result in endocannabinoid release. This study evaluated if post-ictal analgesia occurs in GEPRs, following audiogenic seizures (AGS), and whether this analgesia involves endocannabinoid actions in PAG. Analgesia was evaluated, using thermal stimulation to evoke nociception, measuring changes in paw withdrawal latencies (PWLs) induced by AGS. Endocannabinoid involvement in post-ictal analgesia in GEPRs was evaluated, using focal bilateral microinjection of a cannabinoid (CB1) receptor antagonist (AM251) into PAG. AGS induced a significant increase in PWLs, lasting for ≥ 120 min. Microinjection of AM251 (100 and 200, but not 50 pmol/side) into PAG significantly decreased post-ictal analgesia in GEPRs. Endocannabinoids are also known to activate transient receptor potential vanilloid (TRPV1) receptors, but PAG microinjection of a TRPV1 receptor antagonist (capsazepine) did not affect post-ictal analgesia in GEPRs. These results indicate that AGS in GEPRs induce post-ictal analgesia, which is the first observation of this phenomenon in a genetic epilepsy model. These findings suggest an important role of PAG in post-ictal analgesia. The results also suggest that CB1 receptors in PAG are critical for mediating post-ictal analgesia in GEPRs.

Complete brain‐type creatine kinase deficiency in mice blocks seizure activity and affects intracellular calcium kinetics

Brain-type creatine kinase (CK-B) and ubiquitous mitochondrial creatine kinase (UbCKmit) act as components of local phosphocreatine ATP shuttles that help in the compartmentalization and maintenance of pools of high-energy phosphate molecules in both neurons and glial cells. We investigated the role of these brain-type creatine kinases during extreme energy-demanding conditions in vivo (generalized tonic-clonic seizures) and in vitro. The physiologic response of wild-types and mice lacking both CK-B and UbCKmit (CK--/--mice) to pentylenetetrazole (PTZ)-induced seizures was measured using electroencephalography (EEG) recordings and behavioral monitoring. In vitro intracellular Ca(2+) kinetics in hippocampal granule neurons were monitored upon single and repetitive depolarizations. PTZ induced in only a few CK--/-- mice PTZ seizure-like behavior, but in all wild-types a full-blown seizure. EEG analysis showed that preseizure jerking was associated with high-amplitude discharges. Wild-type EEG recordings showed continuous runs of rhythmic 4-6 Hz activity, whereas no rhythmic EEG activities were observed in the few CK--/-- mice that developed a behavioral seizure. All other CK--/-- mice displayed a sudden postictal depression without any development of a generalized seizure. Hippocampal granule neurons of CK--/-- mice displayed a higher Ca(2+) removal speed following repetitive KCl-induced depolarizations. Deficiency for creatine kinase is affecting brain energy metabolism and will likely contribute to the disturbance of seizure development. Because CK--/-- hippocampal neurons exhibited an increase in Ca(2+) removal rate of elevated intracellular levels, we conclude that altered Ca(2+) clearance in CK--/-- neurons could play a role in the abnormal EEG and seizure activity.

State-dependent slow outlasting activities following neocortical kindling in cats

Some forms of electrographic seizures are generated at the level of the cortical network. Neocortical kindling exhibits a resistance to produce generalized convulsive seizures, and therefore, it was rather difficult to use it to study the cortical epileptogenesis. Here, using supra-threshold cortical kindling, we report electrophysiological patterns of field-potential synchronization and intracellular activities in chronically implanted non-anesthetized cats, during different states of vigilance, and during acute seizures elicited by prolonged (20–60 s) electrical stimulation. Acute seizures were easily elicited during transition from slow-wave sleep (SWS) to waking state. The seizures were mainly clonic accompanied with tonic components followed by prolonged postictal depression. Delayed rhythmic outlasting activities (OA) at ~ 1.5 Hz, first time reported here, followed the postictal depression, and lasted up to 2 h. These activities were clear during waking state, slightly reduced during SWS and completely absent during rapid-eye movement sleep. They started focally and following daily stimulations generalized over the entire cortical surface. Extra- and intracellular neuronal recordings during OA displayed spike-doublets, built on the summation of successive excitatory postsynaptic potentials and fast-prepotentials, entailing an increased dendritic excitation. Our results suggest that such rhythmic long-lasting oscillatory activity outlasting seizures are the key factor of epileptogenesis, leading to epilepsy.

Effects of nociceptin on the spread and seizure activity in the rat amygdala kindling model: Their correlations with 3H-leucyl-nociceptin binding

The effects with pretreatment with nociceptin (0.03-30nmol, i.c.v.) were evaluated on the threshold for eliciting afterdischarge (ADT), generation and spread of seizure activity and postictal depression in rats with kindling stimulation. Nociceptin produced a decrease in ADT (32-45%) in rats with partial seizures (PS, stage II-III), and an increase (61-92%) in rats with generalized seizures (GS, kindled state). Nociceptin did not modify the behavioral changes, spike frequency and duration of afterdischarge elicited at ADT in both experimental groups. In rats with GS, nociceptin enhanced postictal depression (34-44%) evaluated with a recycling paradigm. Autoradiography experiments revealed enhanced nociceptin opioid receptor (NOP) binding in medial amygdala (22-26%), frontal (21-23%) and entorhinal (27-32%) cortices, and reduced binding in the substantia nigra pars compacta (28%) and medial central gray (29%) of rats with PS. The GS group displayed significant decreased NOP binding (40-70%) in most of the brain areas evaluated. These results suggest that nociceptin facilitates ictal activity in rats with PS, whereas in animals with GS, it induces inhibitory effects on ADT and enhances the postictal period. These effects correlate with significant changes in NOP binding.

5-HT 1A receptor agonists modify epileptic seizures in three experimental models in rats

The effects of two serotonergic (5-HT 1A) receptor agonists (8-OH-DPAT; 0.01, 0.1, 0.3, 1 mg/kg, s.c., and Indorenate; 1, 3, 10 mg/kg, i.p.) were evaluated in three type of seizures in male Wistar rats: clonic–tonic convulsions induced by pentylenetetrazol (PTZ, 60 mg/kg, i.p.), status epilepticus (SE) of limbic seizures produced by kainic acid (KA, 10 mg/kg, i.p.) and tonic–clonic seizures by amygdala kindling. 8-OH-DPAT decreased the incidence of tonic seizures and the mortality rate induced by PTZ. Indorenate increased the latency to the PTZ-induced seizures and decreased the percentage of rats showing tonic extension and death. Concerning KA, 8-OH-DPAT augmented the latency and reduced the frequency of wet-dog shake (WDS) and generalized seizure (GS). At high doses it diminished the occurrence and delayed the establishment of SE. Indorenate augmented the latency to WDS, GS and SE, and diminished the number of GS. 8-OH-DPAT and Indorenate did not alter the expression of kindled seizures. However, Indorenate enhanced the refractoriness to subsequent seizures during the postictal depression. Some effects induced by 8-OH-DPAT and Indorenate on seizures evaluated and postictal depression were fully or partially blocked by WAY100635. These results suggest that 5-HT 1A receptor agonists modify epileptic activity depending on the type of seizure.

A comprehensive electrographic and behavioral analysis of generalized tonic-clonic seizures of GEPR-9s

This study records noise-free intracerebral EEG of the genetically epilepsy prone rat (GEPR-9), along with behavioral correlates, during a seizure on unanesthetized freely behaving unrestrained animals. The GEPR-9 exhibits acoustically triggered generalized tonic–clonic seizures, and often times the EEG, recorded with conventional techniques, has resulted in data with imbedded movement artifact. For noise-free video-EEG recordings, we used a previously developed system that consists of a head connector with a FET preamplifier and battery, signal conditioning device (5000x gain, 1 Hz–100 Hz filters), A/D converter and video/PC–PC/video computer boards for recording image data. Each animal was implanted with three monopolar/referential electrodes chosen among the following areas: cortex, inferior colliculus, reticular formation and caudal medulla. The video-EEG data were quite similar for all recorded animals: (1) basal desynchronized EEG before sound stimulus; (2) increase in EEG frequency after stimulus and before seizure onset; (3) high-amplitude polyspikes during massive myoclonic thrusts with or without a very fast running episode; (4) an electrodecremental response during tonic extension; (5) wave and spike complex during forelimb and hindlimb tonic rigidity and posttonic clonus; (6) low-amplitude EEG during postictal depression. Time sequenced spectral analysis also highlights the epileptiform EEG pattern during seizure with high reproducibility between animals. While testing seizure naive GEPR-9s, there was a clear evolution from modest epileptiform EEG activity on the first acoustic stimulation to progressively higher amplitude, duration and frequency epileptiform EEG activity throughout seizure repetition.

Involvement of prolactin, vasopressin and opioids in post-ictal antinociception induced by electroshock in rats

The neurochemical mechanisms involved in post-ictal antinociception remain to be elucidated. Application of electroconvulsive shock (ECS) to rats results in post-ictal antinociception. The objective of this study was to identify endogenous substances that could participate in antinociception during post-ictal depression induced by ECS (70 mA, 60 Hz, 1 s). Antinociception was measured by the rat paw-pressure test, in which increased sensitivity is induced by intraplantar injection of carrageenan. This test proved to be efficient in detecting the electroshock-induced antinociception. Intense post-ictal antinociception was observed over a period of 30 min after the end of the seizure. It was used nonspecific opioid and specific vasopressin antagonists and the prolactin (PRL) release inhibitor to test the reversal of antinociception. Administration of naloxone (5, 7.5 and 10 mg/kg) blocked the post-ictal antinociception. The V 1 (125 μg/kg) and V 2 (250 μg/kg) vasopressin receptor antagonists ([β-mercapto-β,β-cyclopentamethylenepropionyl 1,O-Et-Tyr 2,Val 4,Arg 8]-vasopressin and [adamantaneacetyl 1,O-Et- d-Tyr 2,Val 4,Abu 6,Arg 8,9]-vasopressin) also inhibited the nociceptive response. The antinociception blockade was more intense after administration of the V 1 receptor antagonist. Bromocriptine (4, 8 and 12 mg/kg) was able to reverse antinociception behavior during the post-ictal period. Morphine (1, 2 and 4 mg/kg), vasopressin (12.5, 100 and 400 μg/kg) and prolactin (100, 200 and 400 μg/kg) administration promoted a higher nociceptive threshold. It was administered the three substances with their respective antagonists to verify the opioidergic pathway and vasopressin and prolactin release interactions, and as a positive control. We observed that the tested mediators were released in an independent manner, indicating no interference in which other.