Anticonvulsive effects of neurotropin

The antiepileptic action of neurotropin (Nippon Zoki Pharmaceutied Co. Ltd., Japan) was investigated in acute experiments on rats, mice and cats. The increasing of latent period of the first seizures which were picrotoxin-induced and enhancing of this type of seizures were observed correspondently in 1-24 hours and 8-9 days after intraventricular neurotropin injection. Intraperitoneal neurotropin injection (0.2-0.5 ml) to mice caused dosage-dependent antiseizure action on the model of generalized picrotoxin-induced seizures. +Anticonvulsant++ effect of neurotropin was observed during five days. The intraventricular neurotropin injection to cats led to strychnine (0.1%) induced cortical foci suppression.     

The effect of delta sleep-inducing peptide on the convulsive activity in corasol kindling

The influence of intraperitoneal delta-sleep inducing peptide (DSIP) injection (100 micrograms/kg) on the epileptic activity was investigated in the experiments on Wistar rats and (CBA X C57B1/6)F1 mice. The model of chronically developing epileptic activity--the model of pharmacological kindling--was created by daily repeated corasole injections in subconvulsive doses (30 mg/kg). It has been shown that DSIP injection delayed the manifestation of generalized seizures during kindling, led to the suppression of seizure activity and reduced the mortality rate of animals that developed kindled seizures. The antiepileptic effect of DSIP was observed throughout the period of 5 minutes to 24 hours after the injection. Naloxone (2.5 mg/kg) did not change the antiepileptic effect of DSIP.     

Effects of extracts of different parts of the brain of kindled animals on seizure activity of recipient rats

The peptide-containing fraction was emitted from the hippocampal and ventral mesencephalic region tissue of rats kindled with subconvulsant doses of corazol. Extracts were prepared by the help of hot acetic acid on the stage of generalized clonic-tonic seizure development. The intraventricular injection of VMR-extracts in relatively high dose increased seizure reactions which were induced in intact recipient rats by intraperitoneal corazol injection. The intraventricular injection of the extract in relatively low dose (100 times less) suppressed corazol-induced seizures in recipients. Data are discussed from the point of view of pathological epileptic system formation and the role played by peptides in supporting it's activity during pharmacological kindling.     

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

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

A study of the action of anticonvulsant drugs on an experimental model of epilepsy

Repeated electrical low intensity stimulation of various regions of the brain has been shown to induce epileptic seizure activity. This experimental model of epilepsy has been used in our laboratory in rats. Male rats, anaesthetized with nembutal (20 mg/kg, i.p.) and ketalar (60 mg/kg, i.p.) were implanted stereotaxically with electrodes in the dorsal hippocampus and neocortex and received 2 hours stimulation sessions via the hippocampal electrodes (1 sec, 60 Hz, 200-800 microA) one stimulus per minute, during which electrographical and behavioral seizures were induced. The effect of anticonvulsant drugs was tested on this model: phenobarbital (40 mg/kg) reduced the quantity of epileptic electrographic activity and abolished the behavioral aspects of the seizures; diphenylhydantoin (20 mg/kg) reduced the quantity of epileptic electrographic activity, but had no effect on the behavioral component of the seizures; diazepam (6 mg/kg) only blocked the behavioral component of the seizures leaving the animal stuporous and immobile, but the electrographical component was unaffected; carbamazepine (10 mg/kg) had no effect on the electrographical epileptic seizures and reduced the behavioral aspects, but to a lesser extent than diazepam.     

Convulsive Activity of α-Guanidinoglutaric Acid and the Possible Involvement of 5-Hydroxytryptamine in the α-Guanidinoglutaric Acid-Induced Seizure Mechanism

alpha-Guanidinoglutaric acid (alpha-GGA) was first found in cobalt-induced epileptogenic focus tissue in the cerebral cortex of cats. We examined the effect of alpha-GGA on the electroencephalogram and on the brain 5-hydroxytryptamine (5-HT) level after intraventricular administration into rats. Sporadic low-voltage spikes appeared 4 min after the administration of alpha-GGA. Spikes increased in voltage 6 min after the administration. Multiple spikes appeared 10 min after the administration, and they reached maximal frequency 30 min after the administration. The epileptic discharges disappeared 100 min after the administration. The 5-HT level increased in the right and left cortices 3 min after the administration. The 5-HT level decreased in the mid-brain 5 min after the administration and subsequently in all regions of the brain 10 min after the administration. No change in the 5-HT level was found 30 min and 100 min after the administration. These results show that alpha-GGA induces epileptic seizures in rats after intraventricular administration. The results also suggest that alpha-GGA-induced seizures are associated with abnormal serotonergic function and that they are initiated by a decrease in the 5-HT level.     

Antiepileptic effects of ghrelin on pentylenetetrazole-induced seizures in rats

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

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

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

Antiepileptic effects of cerebellar nucleus dentatus electrical stimulation under different conditions of brain epileptisation

It was shown in acute experiments on cats that high frequency (100-300 Hz) electrical stimulation of dentate nucleus led to the solitary epileptic foci of relatively weak intensity suppression and at the same time caused the activation of stronger focal epileptic activity. Electrical stimulation of nucleus dentatus suppressed the epileptic activity of grand mal type and increased seizures in rats with petit mal form of epileptogenesis which was formed in rats during pentylenetatiozol kindling. It was concluded that there is a relation between the antiepileptic effects of nucleus dentatus irritation and intensity as well as the form of epileptic activity induced experimentally.     

The Antiepileptic Effect of Ghrelin During Different Phases of the Estrous Cycle in PTZ-Induced Seizures in Rat

Catamenial epilepsy is a special form of epilepsy in women whom seizure aggravation is arranged with menstrual cycle that may affect up to 70 % of epileptic women. Antiepileptic effect of Ghrelin hormone has been proved recently. Due to effects of Ghrelin on GABA and LH concentration and periodic variation in the level of estrogen (E₂) and progesterone (P₄) during menstrual cycle, it seems that antiepileptic effect of Ghrelin can be different during various phases of estrous cycle. So this study was conducted to survey antiepileptic effect of Ghrelin during various phases of estrous cycle in rats. 72 adult female Wistar rats in three groups (control, 40 and 80 μg/kg of Ghrelin), each with four subgroups (proestrus, estrus, metestrus and diestrus) were used (n = 6). Then, intracerebroventricular (ICV) injection of Ghrelin (40 and 80 μg/kg) followed by intraperitoneal injection of 80 μg/kg pentylenetetrazole in control and treatment groups were done. Initiation time of myoclonic seizures (ITMS), initiation time of tonic–clonic seizures (ITTS), seizures duration and mortality rate were monitored and recorded for 30 min. Results showed that, ICV injection of Ghrelin significantly increased ITMS and ITTS during luteal phase than follicular phase compared to control group (P < 0.05). Also, seizure duration significantly decreased after ICV injection of Ghrelin during luteal phase and follicular phase compared to control group (P < 0.05). Furthermore, there was no mortality after ICV injection of Ghrelin (40 and 80 μg/kg) during luteal and follicular phases compared to control group (P < 0.05). These results suggest that Ghrelin has antiepileptic effects which are more prominent during luteal phase than follicular phase.     

Detection of 14-3-3zeta in cerebrospinal fluid following experimentally evoked seizures

Surrogate and peripheral (bio)markers of neuronal injury may be of value in assessing effects of seizures on the brain or epilepsy development following trauma. The presence of 14-3-3 isoforms in cerebrospinal fluid (CSF) is a diagnostic indicator of Creutzfeldt-Jakob disease but these proteins may also be present following acute neurological insults. Here, we examined neuronal and 14-3-3 proteins in CSF from rats after seizures. Seizures induced by intra-amygdala microinjection of 0.1 microg kainic acid (KA) caused damage which was mainly restricted to the ipsilateral CA3 subfield of the hippocampus. 14-3-3zeta was detected at significant levels in CSF sampled 4 h after seizures compared with near absence in control CSF. Neuron-specific nuclear protein (NeuN) was also elevated in CSF in seizure rats. CSF 14-3-3zeta levels were significantly lower in rats treated with 0.01 microg KA. These data suggest the presence of 14-3-3zeta within CSF may be a biomarker of acute seizure damage.     

Solitary epileptic seizure--the risk of recurrence

Patients experiencing solitary unprovoked epileptic seizure have different risks of recurrence. The possible risk factors include in particular: structural cerebral lesion and its cause, history of febrile seizures, family history of epilepsy, the type of seizure, epileptiform EEG discharges and the problem of initiation or (or not initiation) of antiepileptic treatment after the first paroxysm. The factors shown above were evaluated in a group of 30 patients with solitary unprovoked epileptic seizure. Regarding recurrence of epileptic seizure, the only significant factor appeared to be initiation of treatment after the first unprovoked paroxysm (p<0.001). We observed a 30% and 33.33% risk of recurrence following the initial epileptic seizure in patients after the first unprovoked seizure in less than 1 and 3 years, respectively.     

Detection of 14-3-3ζ in cerebrospinal fluid following experimentally evoked seizures

Surrogate and peripheral (bio)markers of neuronal injury may be of value in assessing effects of seizures on the brain or epilepsy development following trauma. The presence of 14-3-3 isoforms in cerebrospinal fluid (CSF) is a diagnostic indicator of Creutzfeldt–Jakob disease but these proteins may also be present following acute neurological insults. Here, we examined neuronal and 14-3-3 proteins in CSF from rats after seizures. Seizures induced by intra-amygdala microinjection of 0.1 µg kainic acid (KA) caused damage which was mainly restricted to the ipsilateral CA3 subfield of the hippocampus. 14-3-3ζ was detected at significant levels in CSF sampled 4 h after seizures compared with near absence in control CSF. Neuron-specific nuclear protein (NeuN) was also elevated in CSF in seizure rats. CSF 14-3-3ζ levels were significantly lower in rats treated with 0.01 µg KA. These data suggest the presence of 14-3-3ζ within CSF may be a biomarker of acute seizure damage.     

Models of epileptic seizures in immature rats

Models of basic types of epileptic seizures are elaborated not only in adult but also in immature rodents. It is important because at least half of human epilepsies starts during infancy and childhood. This paper presents a review of chemically and electrically induced models of generalized convulsive and nonconvulsive (absence) seizures as well as models of partial simple (neocortical) and complex (limbic) seizures in immature rats. These models can also serve as a tool for study the development of central nervous system and motor abilities because the level of maturation is reflected in seizure semiology. Age-dependent models of epileptic seizures (absences and flexion seizures) are discussed. Models of seizures in immature animals should be used for testing of potential antiepileptic drugs.     

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

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

Influence of cerebro-spinal fluid of picrotoxin kindled rats on seizure susceptibility and locomotor activity of recipients.

Repeated picrotoxin administration (ip) in subthreshold doses in rats resulted in kindling of generalized seizures. Decrease of locomotor activity in kindled rats occurred in interictal periods. Intra-cerebroventricular microinjection to intact recipients of cerebrospinal fluid (CSF) of kindled but not intact rats or those after acute picrotoxin-induced convulsions, induced a decrease of locomotor activity and severity of acute picrotoxin induced seizures. These effects of CSF were blocked by naloxone pretreatment and were absent after injection of CSF to which protease inhibitors were not added. It is concluded that the release of endogenous opioid peptide substance(s) takes place in CSF of kindled animals which cause the interictal decrease of locomotor activity and may play the role of endogenous anticonvulsive factors controlling epileptic activity induction.     

Inhibition of metaphit-induced audiogenic seizures by APV in rats.

The influence of APV ((+/-)-2-amino-5-phosphonovaleric acid) on EEG activity and behavior was studied on a model of epilepsy induced by intraperitoneal administration of metaphit (1-(1-(3-isothiocyanatophenyl)-cyclohexyl)-piperidine). Male Wistar rats received an injection of metaphit (10 mg/kg) and were subjected to intense audio stimulation (100+/-3 dB, 60 s) at hourly intervals during the experiment. The seizures were classified according to a four point scale ranging from 0 (no seizure) to 3 (tonic convulsions). In our report we studied the time course which revealed the maximum incidence and severity of seizures 7-12 h after the injection (10 out of 12 rats, with severity of 2.25+/-0.32). APV (0.05, 0.1, 0.2 and 0.3 micromol) was injected intracerebroventricularly at the time of fully developed convulsions. APV inhibited seizures in a dose-dependent manner. The minimum dose, which completely blocked seizures in all animals, was 0.3 micromol, while ED50 were 0.11, 0.10 and 0.07 micromol against running, clonus and tonus, respectively. In contrast to behavioral inhibition of convulsions, metaphit-provoked epileptiform activity was not abolished by APV, and represented a prerequisite for the reappearance of behavioral seizures. It is suggested that APV is rather an anticonvulsant than an antiepileptic agent in this model of epilepsy.     

The influence of neonatal ketamine injection on pain sensitivity and audiogenic seizures in adult rats

The remote effects of neonatal (on the 3d-to-9th postnatal days) ketamine injections (10 and 50 mg/kg in 20 microliters of distilled water, s.c.) were analyzed in adult Wistar, WAG/Rij, and KM (a strain with high audiogenic sensitivity) rats. Both ketamine and water injections increased pain sensitivity in adult rats. Neonatally injected water increased the mean score of seizures in Wistar and WAG/Rij, whereas ketamine water solution injected in the dose of 50 mg/kg did not change the seizure intensity (as compared to the intact control). Consequently, ketamine significantly reduced the mean score of the audiogenic seizure fit without change in its latency. In highly sensitive KM rats the neonatally injected ketamine (50 mg/kg) significantly shortened the mean latency of the fit onset, and fit stages developed faster. Thus, the neonatal ketamine injection increased the audiogenic seizure susceptibility of brain structures in KM rats.     

Anti-epileptic effect of the new calcium channel blocker IOS-1.1212]

In experiments on freely moving male Wistar rats it was shown that IOS-1.1212 (1,4-dihydropyridine) in a dose 2 and 10 mg/kg (i. p.) suppressed the penicillin-induced focal epileptic activity in cerebral cortex. Similar suppressing effect of IOS-1.1212 was shown on acute generalized tonic-clonic pentylenetetrazol (PTZ) seizures (75 mg/kg i. p.) and on chronic PTZ administration (PTZ-kindling, 30 mg/kg i. p. during 30 days): when injected 30 min before each PTZ administration it delayed the development of kindling-induced seizures susceptibility in randomized animals (series 1) and attenuated the severity of seizures in PTZ-sensitive animals (series 2). However, IOS-1.1212 had no effect on the strychnine-induced focal epileptic activity. In male Icr:Icl mice IOS-1.1212 in a dose 1.5 and 5 mg/kg also influenced the PTZ convulsions (i. v. titration of 1% solution at a rate of 0.01 ml/s) and had no effect on the strychnine convulsions (i. v. titration of 0.01% solution at a rate of 0.01 ml/s) and on maximal electroshock. In addition, IOS-1.1212 significantly increased antiepileptic effect of phenobarbital on maximal electroshock.     

Ubiquitin Carboxy-Terminal Hydrolase L1 (UCH-L1) is increased in cerebrospinal fluid and plasma of patients after epileptic seizure

ABSTRACT: BACKGROUND: Clinical and experimental studies have demonstrated that seizures can cause molecular and cellular responses resulting in neuronal damage. At present, there are no valid tests for assessing organic damage to the brain associated with seizure. The aim of this study was to investigate cerebrospinal fluid (CSF) and plasma concentrations of Ubiquitin carboxy-terminal hydrolase L1 (UCH-L1), a sensitive indicator of acute injury to brain neurons, in patients with tonic--clonic or partial secondarily generalized seizures due to various etiologies. METHODS: CSF and plasma concentrations of UCH-L1 were assessed in 52 patients within 48 hours after epileptic seizure and in 19 controls using ELISA assays. RESULTS: CSF obtained within 48 hours after seizure or status epilepticus (SE) presented significantly higher levels of UCH-L1 compared to controls (p = 0.008). Plasma UCH-L1 concentrations were negatively correlated with time to sample withdrawal. An analysis conducted using only the first 12 hours post-seizure revealed significant differences between concentrations of UCH-L1 in plasma and controls (p = 0.025). CSF and plasma concentrations were strongly correlated with age in patients with seizure, but not in control patients. Plasma UCH-L1 levels were also significantly higher in patients after recurrent seizures (n = 4) than in those after one or two seizures (p = 0.013 and p = 0.024, respectively). CONCLUSION: Our results suggest that determining levels of neuronal proteins may provide valuable information on the assessment of brain damage following seizure. These data might allow clinicians to make more accurate therapeutic decisions, to identify patients at risk of progression and, ultimately, to provide new opportunities for monitoring therapy and targeted therapeutic interventions.