Antiepileptogenic and anticonvulsive actions of levetiracetam in a pentylenetetrazole kindling model

doi:10.1016/j.eplepsyres.2010.01.011

Epilepsy Research

Volume 89, Issues 2–3, May 2010, Pages 360-364

https://doi.org/10.1016/j.eplepsyres.2010.01.011 Get rights and content

Summary

Levetiracetam (LEV) is a unique antiepileptic drug that preferentially interacts with synaptic vesicle protein 2A (SV2A). To evaluate the antiepileptogenic action of LEV, we studied its effects on the development and acquisition of pentylenetetrazole (PTZ) kindling and compared them to those of sodium valproate (VPA). Anticonvulsive actions of LEV in PTZ-kindled animals were also determined. LEV did not affect PTZ seizures in naïve animals even at high doses (≈300 mg/kg, i.p.). However, combined treatment of LEV (30 and 100 mg/kg, i.p.) with PTZ significantly suppressed the development and acquisition of PTZ kindling. In addition, LEV at relatively low doses (3–30 mg/kg, i.p.) inhibited PTZ-evoked seizures in fully kindled animals. In contrast to LEV, VPA at sub-anticonvulsive doses (30 and 100 mg/kg, i.p.) failed to prevent the development of PTZ kindling and its anticonvulsive potency was similar in PTZ-kindled and naïve mice. The present study shows that LEV contrasts VPA by preventing the development of PTZ kindling and inhibiting seizures selectively in kindled animals.

Introduction

Levetiracetam (LEV) is a unique antiepileptic drug (AED) which preferentially interacts with synaptic vesicle protein 2A (SV2A) without affecting activities of neurotransmitter receptors or ion channels (Lynch et al., 2004, Sasa, 2006, Kaminski et al., 2008). Unlike conventional AEDs, LEV is not active in the classical convulsion tests (i.e., maximal electroshock- and maximal pentylenetetrazole (PTZ)-evoked seizures) (Löscher and Hönack, 1993, Klitgaard et al., 1998, Bastlund et al., 2005), but it inhibits seizures in various animal models including kindled animals (e.g., corneal- and amygdala kindling) (Löscher and Hönack, 1993, Klitgaard et al., 1998, Löscher et al., 1998) and genetically defined animal models of epilepsy (Gower et al., 1995, Bouwman and van Rijn, 2004, Yan et al., 2005, Ji-qun et al., 2005). In addition, previous studies demonstrated that LEV can inhibit the development of amygdala kindling in rats, suggesting that LEV has antiepileptogenic activities (Löscher et al., 1998, Husum et al., 2004, Gu et al., 2004). Nonetheless, a recent study by Matveeva et al. (2008) showed that LEV retarded the development of amygdala kindling, but could not prevent kindling acquisition. Studies using animals with spontaneous recurrent seizures after status epilepticus also demonstrated the lack of effectiveness of LEV against the epileptogenesis (Brandt et al., 2007). Thus, the antiepileptogenic potential of LEV is still unclear and remains to be verified using different animal models.

In order to address this question further, we studied the effects of LEV on the development and acquisition of PTZ-induced kindling in mice, and compared them with those of the typical AED sodium valproate (VPA).

Section snippets

Methods

Male ddY mice (Japan SLC, Shizuoka, Japan) weighing 20–25 g were used. Animals were housed in air-conditioned rooms under a 12-h light/dark cycle (light on: 7:00 a.m.) and allowed ad libitum access to food and water. The housing conditions of the mice and animal care methods complied with NIH guide for the care and use of laboratory animals. The experimental protocols of this study were approved by the Experimental Animal Research Committee at Osaka University of Pharmaceutical Sciences.

In order

Results

In naïve animals, LEV did not affect PTZ seizures even at high doses up to 300 mg/kg (i.p.) while VPA inhibited the seizures with an ED₅₀ value of 229 mg/kg (i.p.) (Table 1). We therefore set the test doses of LEV and VPA at 30 and 100 mg/kg (i.p.), and these doses were repeatedly administered to the animals 30 min before PTZ (40 mg/kg, i.p.) injection for 12 days.

Repeated administration of sub-convulsive PTZ (40 mg/kg, i.p.) progressively increased seizure susceptibility in mice during the 12-day

Discussion

The present study demonstrated that repeated treatments with LEV effectively inhibited development and acquisition of PTZ kindling. In addition, LEV showed a significant ability to inhibit PTZ-evoked seizures specifically in kindled animals while being inactive in naïve animals. These characteristics are different from those of VPA, which failed to prevent the development of PTZ kindling and inhibited PTZ seizures in fully kindled and naïve animals at equipotent doses. Our results revealed that

Acknowledgments

This work was partly supported by the Japan Epilepsy Research Foundation. We thank UCB Japan (Tokyo, Japan) for kindly donating a sample of LEV.

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Kappa opioid receptor (KOR) agonists have anticonvulsant effect but their antiepileptogenic effect is unknown. U50488, a selective KOR agonist is used to determine its effect on status epilepticus (SE), spontaneous convulsive seizures (SS) and cognitive impairment in rat lithium-pilocarpine SE model. Effect of an antiepileptic drug levetiracetam is also studied.
Male Wistar rats with SE were divided into three groups namely, LiP, LiP + U50488 (10 mg/kg, i.p.) and LiP + levetiracetam (400 mg/kg, i.p.) group. SE was terminated after 90 min of its onset with diazepam (15 mg/kg, i.p.) and phenobarbitone (25 mg/kg, i.p.). Drug treatment was started after 15 min of onset of SE and repeated once after 4 h. Rats were video monitored 12 h daily (9 AM to 9 PM) to determine severity of SE using modified Racine scale and onset and frequency of SS from day 0 to day 21. Morris water maze (MWM) test was done at baseline i.e. day −1 (before lithium administration) and day 22, to assess cognitive impairment.
As compared to LiP, U50488 decreased the severity of SE (1.98 ± 0.13 vs 2.95 ± 0.12; p-value < 0.0001) but not levetiracetam (2.62 ± 0.09; p-value = 0.3112). Survival increased with both U50488 (90%, n = 10) and levetiracetam (81.8%, n = 11) as compared to NS (56.2%, n = 16). No effect on onset and frequency of SS was found in U50488/levetiracetam group. U50488 improved seizures-induced cognitive impairment. Levetiracetam group showed thigmotactic (wall hugging) behaviour in MWM in 8 out of 9 rats.
Acute treatment with U50488, a kappa opioid receptor agonist has a beneficial effect on SE, SE-related mortality and memory impairment. The dual protective effect of U50488 on seizures and related cognitive impairment is advantageous over currently used antiseizure drugs which are known to cause cognitive impairment.
TRPV1 mediates the anticonvulsant effects of acetaminophen in mice
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In contrast, valproate is effective at preventing kindling development and blocking the fully kindled seizures (Post, 2004). However, it was reported that valproate at sub-anticonvulsive doses failed to prevent the development of pentylenetetrazol kindling (Ohno et al., 2010). In the present study, acetaminophen at doses of 100–300 mg/kg (i.p.) had no effect against the acute pentylenetetrazol seizures.
Acetaminophen is one of the most commonly used analgesic and antipyretic drugs. It has been reported that acetaminophen has anticonvulsant effects in several animal models of seizure. An active metabolite of acetaminophen, AM404, inhibits the uptake of the endocannabinoid anandamide. However, the mechanism of the anticonvulsant effect of acetaminophen is unknown.
This study was performed to examine whether or not acetaminophen can protect against pentylenetetrazol-induced kindling in mice and to investigate the precise mechanisms of the anticonvulsant effect of acetaminophen using the fully kindled mouse models.
Repeated administration of acetaminophen significantly delayed the progression of seizure severity induced by pentylenetetrazol. Additionally, acetaminophen showed a dose-dependent anticonvulsant activity against fully pentylenetetrazol-kindled seizures. AM404 also exhibited a dose-dependent anticonvulsant activity in fully kindled animals. The anticonvulsant activity of acetaminophen was antagonized by capsazepine and AMG9810, two transient receptor potential vanilloid-1 (TRPV1) antagonists. However, the transient receptor potential ankyrin 1 (TRPA1) antagonist HC030031 and CB1 receptor antagonist AM251 had no effect.
These findings suggest that acetaminophen has an anticonvulsant effect in pentylenetetrazol-kindled mouse models and TRPV1 mediates the anticonvulsant action.
Adjuvant quercetin therapy for combined treatment of epilepsy and comorbid depression
2017, Neurochemistry International
Epilepsy is one of the major neurological disorders frequently associated with psychiatric disorders such as depression. The predisposition of tryptophan metabolism towards kynurenine pathway has been reported as one of the plausible reasons for association of depression in epilepsy. Hence, this study was envisaged to evaluate the dose dependent inhibition of indoleamine 2,3-dioxygenase (IDO) enzyme employing quercetin (screened employing in vitro method) with levetiracetam for combined management of epilepsy and comorbid depression. Kindling was induced in male swiss albino mice by administration of pentylenetetrazole subconvulsive doses (35 mg/kg, i.p.) at an interval of 48 ± 2 h. Kindled animals were treated with vehicle, levetiracetam (40 mg/kg/day i.p.) levetiracetam in combination with different doses of quercetin (10 mg/kg; 20 mg/kg; 40 mg/kg)/day/p.o. for 15 days. Except naïve, all the groups were challenged with pentylenetetrazole (35 mg/kg i.p.) on day 5, 10, and 15 to evaluate the seizure severity score. Depression was evaluated in all experimental groups using the tail suspension and sucrose preference test on days 1, 5, 10 and 15, 2 h after pentylenetetrazole challenge. Results suggested that vehicle treated kindled animals were significantly associated with depression. Chronic levetiracetam treatment significantly reduced seizure severity score, but further worsened the associated depression. Quercetin supplementation with levetiracetam dose dependently ameliorated depression associated with epilepsy. Neurochemical and biochemical findings also supported the behavioural findings of the study. Thus, our results suggested that supplementation of quercetin with levetiracetam could be explored further for combined treatment of epilepsy and comorbid depression.
Kindling: A Model and Phenomenon of Epilepsy
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Kindling was first recognized in 1968 by Graham Goddard during experiments investigating whether learning in rats was disrupted by repeated hippocampal electrical stimulation. Goddard observed that repeated electrical stimulation of a variety of brain pathways unexpectedly evoked gradually evolving seizures and permanent progressive increases in seizure susceptibility that he described as “kindling,” and recognized as potentially significant for epilepsy.
New model of pharmacoresistant seizures induced by 3-mercaptopropionic acid in mice
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The fact that DZP and LEV elicit protection in MP23 animals at doses that they were not effective in control animals suggests that these AEDs have a strong anticonvulsant action on a convulsive brain (which is not observed on animals with seizure triggered by an acute episode). In agreement with this idea, Ohno et al. (2010) observed that LEV, in a similar dose, significantly suppressed the development and acquisition of PTZ kindling, and they found an increase in the hippocampal levels of SV2A protein (a primary action site of LEV) in fully kindled animals (Ohno et al., 2009). It is important to note that current models of drug resistant epilepsy require extremely long times for its setting up, due to the resistance induction period and the subsequent treatment used for the selection of nonresponders.
About 30% of the patients with epilepsy do not respond to clinically established anticonvulsants, despite having effective concentrations of the antiepileptic drug in plasma. Therefore, new preclinical models of epilepsy are needed to identify more efficacious treatments. We describe here a new drug-resistant seizure model in mice to be used at the early stages of pre-clinical trials. This model consists in inducing daily generalized seizures for 23 consecutive days by administration of 3-mercaptopropionic acid (MP). As a result, 100% of animals become resistant to phenytoin and 80% to phenobarbital. Such resistance is strongly associated with the overexpression of P-glycoprotein (Pgp), observed in cerebral cortex, hippocampus and striatum while resistance to Pgp nonsubstrate drugs such as carbamazepine, diazepam and levetiracetam is not observed.
This model could be useful for screening novel anticonvulsant drugs with a potential effect on pharmacoresistant seizures treatment.
Omega 3 polyunsaturated fatty acids enhance the protective effect of levetiracetam against seizures, cognitive impairment and hippocampal oxidative DNA damage in young kindled rats
2015, Pharmacology Biochemistry and Behavior
Citation Excerpt :
Treatments of groups III-V are followed 1 h by PTZ injection on alternate-day treatment schedule. Selection of the used doses depends on the previous studies, (Ohno et al., 2010) for LEV and (Abdel-Wahab et al., 2015) for OM3. Groups VI–VIII received LEV 30 mg/kg, OM3 200 mg/kg and their combination, respectively, without PTZ every other day to study any effects of LEV, OM3 and their combination on cognitive functions or biochemical parameters.
Levetiracetam (LEV) is a unique, effective, relatively safe antiepileptic drug that preferentially interacts with synaptic vesicle protein 2A (SV2A). This study aimed to explore the effect of combined treatment of LEV with omega 3 (OM3) on cognitive impairment and hippocampal oxidative stress and DNA damage induced by seizures in the PTZ-kindled young rat model. Cognitive functions, biomarkers of oxidative stress, and DNA damage were assessed in PTZ-kindled young rats pretreated with single and combined treatment of LEV (30 mg/kg, i.p.) and OM3 (200 mg/kg, p.o.). Pretreatment with LEV and OM3 at the tested doses significantly attenuated PTZ-induced seizures and decreased cognitive impairment in both passive avoidance and elevated plus maze tests in the PTZ-kindled rats. Moreover, the increase in hippocampal glutamate, malondialdehyde and 8-hydroxy-2-deoxyguanosine (8-OHdG) levels, as well as the decrease in reduced glutathione (GSH) levels and GSH-peroxidase and superoxide dismutase activities induced by PTZ kindling, significantly decreased. These effects were higher with combined treatment of LEV with OM3 and significantly more than the observed effects of single LEV or OM3. In conclusion, the combined treatment of LEV with OM3 is more effective in seizure control and alleviating the cognitive impairment induced by PTZ kindling in the young rat model, the effects that result from the decrease in hippocampal oxidative stress and DNA damage which can be attributed to the antioxidant properties of both LEV and OM3. These results may be promising for the use of LEV and OM3 combination in the treatment of epileptic children.

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Short communicationAntiepileptogenic and anticonvulsive actions of levetiracetam in a pentylenetetrazole kindling model

Summary

Introduction

Section snippets

Methods

Results

Discussion

Acknowledgments

Neuropharmacology

Seizure

Neuropharmacology

Epilepsy Res.

Epilepsy Behav.

Neuropharmacology

Eur. J. Pharmacol.

Eur. J. Pharmacol.

Prog. Neurobiol.

Biochem. Biophys. Res. Commun.

J. Pharmacol. Sci.

Short communication
Antiepileptogenic and anticonvulsive actions of levetiracetam in a pentylenetetrazole kindling model