Influence of etoricoxib on anticonvulsant activity of phenytoin and diazepam in experimental seizure models in mice

Objectives Our aim was to investigate the effect of etoricoxib on the anticonvulsant activity of phenytoin and diazepam against seizure models in mice. In addition the acute adverse effect of etoricoxib was assessed with a chimney test. Methods The maximal seizure pattern was induced in mice by giving an alternating current of 50 mA for 0.2 s, while chemical seizures were induced by intraperitoneal injection of pentylenetetrazole at its CD97 dose (97% convulsive dose for the clonic phase). Test drug was administered 45 min before the electrical or chemical induction of seizures in combination with conventional antiepileptics. The ability of the test drug to reduce or abolish the extensor phase of maximal electroshock and clonic‐type seizures in the chemical induction method was selected as anti‐seizure criteria. Key findings Concurrent treatment with etoricoxib at an oral dose of 10 mg/kg reduced the anticonvulsant potency of phenytoin. The protective effects of diazepam against pentylenetetrazole‐induced convulsions was significantly increased and the mortality rate was reduced by concurrent treatment with etoricoxib (10 mg/kg p.o.) when compared with diazepam groups. No neurotoxic effect was observed with etoricoxib (10 mg/kg p.o.) and it had no impact on motor coordination in the chimney test in mice. Etoricoxib applied at its highest dose (10 mg/kg) significantly enhanced the free plasma levels of diazepam whereas the free plasma levels of phenytoin were significantly reduced. Conclusions The obtained results suggest that the preferential cyclooxygenase‐2 inhibitor etoricoxib significantly reduced the anticonvulsant action of phenytoin and significantly increased the beneficial action of diazepam against maximal electroshock and pentylenetetrazole‐induced convulsions in a mouse model.     

Characterization of the anticonvulsant activity of doxepin in various experimental seizure models in mice

In this paper, the anticonvulsant characteristics of doxepin were evaluated in numerous experimental seizure models, including maximal electroshock (MES)-, pentylenetetrazole (PTZ)-, isoniazid (ISO)-, 3-mercaptopropionic acid (3-MP)-, bicuculline (BIC)-, thiosemicarbazide (THIO)-, and strychnine (STR)-induced seizures. In addition, the acute adverse-effect profile of doxepin with respect to impairment of motor coordination was assessed with a mouse rotarod test. The evaluation of the time-course and doseresponse relationships for doxepin provided evidence that the peak maximum anticonvulsant activity and acute adverse effects occurred 5 min after intraperitoneal (ip) administration. The results also revealed that doxepin had excellent anticonvulsant activity against maximal electroshock-induced seizures in mice with a median effect value (ED₅₀) of 6.6 mg/kg. The assessment of acute adverse effects in the rotarod test revealed that doxepin induced acute neurotoxicity, and its median toxic dose (TD₅₀) was 26.4 mg/kg. Additionally, doxepin showed anticonvulsant activity in several chemically-induced seizure models, including ISO, 3-MP, BIC, and THI. Based on this study, we can conclude that the antidepressant drug doxepin may be useful for treatment of depression in patients with epilepsy due to its short time to peak maximum anticonvulsant activity after ip administration (5 min) and remarkable anticonvulsant activity (6.6 mg/kg).     

Influence of orphenadrine upon the protective activity of various antiepileptics in the maximal electroshock-induced convulsions in mice

Orphenadrine is an anticholinergic drug used in the treatment of Parkinson’s disease, and is also known to exert nonspecific antagonistic activity at the phencyclidine binding site of the N-methyl-D-aspartate (NMDA) receptor. The aim of this study was to assess the anticonvulsant properties of orphenadrine and to evaluate its effect on the anticonvulsant activity of antiepileptic drugs against maximal electroshock-induced seizures in mice. Orphenadrine given at a dose of 5.65 mg/kg elevated the electrical seizure threshold from 5.7 (5.4 – 6.1) to 6.8 (6.3–7.3) mA, while a dose of 2.8 mg/kg was ineffective. The ED₅₀ values of orphenadrine administered 10,30 and 120 min before maximal electroshock-induced convulsions were 16.8 (11.3–25.1), 17.8 (15.7–20.0) and 25.6 (23.3–28.3) mg/kg, respectively. Orphenadrine at a sub-threshold dose of 2.8 mg/kg significantly enhanced the anticonvulsant activity of valproate by reducing its ED₅₀ value from 315.8 (270.0–369.4) to 245.9 (207.1–292.0) mg/kg without affecting the free plasma levels of valproate. However, orphenadrine failed to enhance the protective activity of carbamazepine, phenytoin, phenobarbital, lamotrigine, topiramate, or oxcarbazepine against maximal electroshock-induced seizures.     

Effects of sarcosine,a glycine transporter type 1 inhibitor,in two mouse seizure models

Sarcosine, a natural amino acid found in muscles and other body tissues, is an endogenous glycine transporter type 1 inhibitor that increases the glycine concentration, resulting in an indirect potentiation of the N-methyl-D-aspartate (NMDA) subtype of glutamate receptors. Sarcosine, similar to other NMDA receptor-activating agents, is an effective adjuvant in the treatment of schizophrenia. It is widely accepted that increased glutamatergic neurotransmission is involved in the initiation and propagation ofseizures. Because sarcosine facilitates NMDAreceptor function, it may affect the seizure threshold. Therefore, we examined the effects of sarcosine on the seizure threshold in two different mouse seizure models: the timed intravenous (iv) pentylenetetrazol (PTZ) infusion test and the maximal electroshock seizure threshold test. In the iv PTZ test, sarcosine did not exert a significant effect on the seizure threshold at any of the doses tested (100,200,400 and 800 mg/kg, ip). However, at doses of400 and 800 mg/kg, sarcosine significantly raised the threshold for electroconvulsions (p < 0.01). The present findings indicate that sarcosine did not lower the seizure threshold. Conversely, sarcosine showed weak anticonvulsant properties by increasing the threshold current for the induction of tonic seizures. Therefore, sarcosine may be considered as a safe adjuvant treatment for schizophrenia without proconvulsant risk. In addition, the compound may serve as an interesting addition to epilepsy treatment.     

Nefopam enhances the protective activity of antiepileptics against maximal electroshock-induced convulsions in mice

Nefopam is a centrally acting non-opioid analgesic with a mechanism of action that is not completely understood. Adverse effects associated with the therapeutic use and overdose of nefopam are mainly associated with the central nervous system, such as hallucinations, cerebral edema and convulsions. The aim of this study was to assess the effect of nefopam on the electrical threshold and its influence on the protective activity of antiepileptic drugs in the maximal electroshock test in mice. A 5 mg/kg dose of nefopam significantly elevated the electric seizure threshold, while a dose of 1 mg/kg failed to protect mice against electroconvulsion. At a subthreshold dose of 1 mg/kg, nefopam significantly enhanced the anticonvulsant activity of valproate against electroconvulsions. The protective activity of phenobarbital and phenytoin was significantly enhanced by co-administration of nefopam at the 5 mg/kg dose, but this same dose of nefopam failed to affect the protective activity of carbamazepine. In conclusion, nefopam exerts an anticonvulsive effect when given alone and significantly enhances the protective activity of certain antiepileptic agents against electroconvulsions induced in mice.     

Evaluation of the anticonvulsant activity of 6-(4-chlorophenyoxy)-tetrazolo[5,1-a]phthalazine in various experimental seizure models in mice

This study investigated the anticonvulsant activity of a new phthalazine tetrazole derivative, QUAN-0808 (6-(4-chlorophenoxy)-tetrazolo[5,1-a]phthalazine), in the mouse maximal electroshock (MES) seizure model. The neurotoxicity of QUAN-0808 was investigated using the rotarod neurotoxicity test in mice. QUAN-0808 exhibited higher activity (median effective dose, ED₅₀ = 6.8 mg/ kg) and lower neurotoxicity (median toxic dose, TD₅₀ = 456.4 mg/kg), resulting in a higher protective index (PI = 67.1) compared with carbamazepine (PI = 6.4). In addition, QUAN-0808 exhibited significant oral anticonvulsant activity (ED₅₀ = 24 mg/kg) against MES-induced seizure with low neurotoxicity (TD₅₀ > 4500 mg/kg) in mice, resulting in a PI value of more than 187.5. QUAN-0808 was also tested in chemically induced animal models of seizure (pentylenetetrazole [PTZ], isoniazid [ISO], thiosemicarbazide [THIO] and 3-mercaptopropionic acid [3-MP]) to further investigate the anticonvulsant activity; QUAN-0808 produced significant anticonvulsant activity against seizures induced by ISO, THIO and 3-MP.     

抗癫(癎)药物对戊四氮点燃大鼠癫(癎)发作及生命影响的研究

目的:研究抗癫癎药物(AEDs)对戊四氮(PTZ)点燃大鼠发作的控制与生存的影响。方法:选用健康雄性成年SD大鼠70只,随机分为7组,每组10只。随机选取1组作为正常对照组(NS组),其余6组用PTZ点燃,制备大鼠癫癎模型;致癎后随机选取1组作为癫癎对照组(PTZ组),其余5组分别给予卡马西平(CBZ组)、苯妥英钠(PHT组)、丙戊酸钠(VPA组)、托吡酯(TPM组)及拉莫三嗪(LTG组)控制癫癎发作。2周后观察大鼠的癫癎发作控制率和病死率。结果:PHT组有4只(4/10)持续发作,TPM组有3只(3/10)持续发作,其他3组控制良好,癫癎未再发作。PTZ组和TPM组各死亡1只(1/10),LTG组死亡2只(2/10)。结论:PHT、TPM对PTZ点燃的癫癎发作控制不良;TPM、LTG可导致大鼠死亡。     

Low-frequency stimulation of the external globus palladium produces anti-epileptogenic and anti-ictogenic actions in rats

Aim:

To investigate the anti-epileptic effects of deep brain stimulation targeting the external globus palladium (GPe) in rats.

Methods:

For inducing amygdala kindling and deep brain stimulation, bipolar stainless-steel electrodes were implanted in SD rats into right basolateral amygdala and right GPe, respectively. The effects of deep brain stimulation were evaluated in the amygdala kindling model, maximal electroshock model (MES) and pentylenetetrazole (PTZ) model. Moreover, the background EEGs in the amygdala and GPe were recorded.

Results:

Low-frequency stimulation (0.1 ms, 1 Hz, 15 min) at the GPe slowed the progression of seizure stages and shortened the after-discharge duration (ADD) during kindling acquisition. Furthermore, low-frequency stimulation significantly decreased the incidence of generalized seizures, suppressed the average stage, and shortened the cumulative ADD and generalized seizure duration in fully kindled rats. In addition, low-frequency stimulation significantly suppressed the average stage of MES-induced seizures and increased the latency to generalized seizures in the PTZ model. High-frequency stimulation (0.1 ms, 130 Hz, 5 min) at the GPe had no anti-epileptic effect and even aggravated epileptogenesis induced by amygdala kindling. EEG analysis showed that low-frequency stimulation at the GPe reversed the increase in delta power, whereas high-frequency stimulation at the GPe had no such effect.

Conclusion:

Low-frequency stimulation, but not high-frequency stimulation, at the GPe exerts therapeutic effect on temporal lobe epilepsy and tonic-colonic generalized seizures, which may be due to interference with delta rhythms. The results suggest that modulation of GPe activity using low-frequency stimulation or drugs may be a promising epilepsy treatment.     

Synthesis and evaluation of anticonvulsant activities of 7‐phenyl‐4,5,6,7‐tetrahydrothieno[3,2‐b ]pyridine derivatives

A series of 7‐phenyl‐4,5,6,7‐tetrahydrothieno[3,2‐b]pyridine derivatives containing triazole and other heterocycle substituents (methyltriazole, tetrazole, and triazolone) is described. Two experimental methods, maximal electroshock (MES) and subcutaneous pentylenetetrazole (scPTZ), were used to evaluate the anticonvulsant activity of the target compounds. Moreover, the neurotoxicity (NT) was tested using the Rotarod test. 5‐(4‐Chlorophenyl)‐4,5‐dihydrothieno[2,3‐e][1,2,4]triazolo[4,3‐a]pyridine ( 6c ) showed the best anticonvulsant activity. In the MES and PTZ experiments, the 50% effective dose (ED₅₀) values of compound 6c were 9.5 and 20.5 mg/kg, respectively. From the therapeutic index (PI) values, 6c (MES and PTZ with PI values of 48.0 and 22.2, respectively) showed better safety than the clinical drugs carbamazepine (MES with PI value of 6.4) and ethosuximide (PTZ with PI value of 3.2). The biological activities of the compounds were verified by using molecular docking studies. Compound 6c showed significant interactions with residues at the benzodiazepine‐binding site on gamma‐aminobutyric acid A (GABA_A) receptors. The results of in vivo GABA estimation and bicuculline‐induced seizures showed that 6c may have an effect on the GABA system. The physicochemical and pharmacokinetic properties of the target compounds were predicted.     

Cytisine inhibits the anticonvulsant activity of phenytoin and lamotrigine in mice

BackgroundCytisine (CYT), the most commonly used drug for smoking cessation in Poland, was experimentally found to induce convulsions. There is a lack of studies on the influence of CYT on the anticonvulsant activity of antiepileptic drugs (AEDs).MethodsThe effects of CYT on the anticonvulsant activity of six AEDs were examined in maximal electroshock (MES)-induced seizures in mice.ResultsSingle intraperitoneal (ip) administration of CYTin a subthreshold dose of 2 mg/kg antagonized the protective activity of ip phenytoin and lamotrigine against MES-induced seizures in mice. Adose of 1 mg/kg did not reverse the protective activity of phenytoin and lamotrigine. CYT in a dose of 2 mg/kg had no effect on the anticonvulsive activity of carbamazepine, oxcarbazepine, phenobarbital, and valproate magnesium.ConclusionCYT ability to antagonize the anticonvulsive activity of phenytoin and lamotrigine can be of serious concern for epileptic smokers, who might demonstrate therapeutic failure to these drugs resulting in possible breakthrough seizure attacks.     

天麻对小鼠戊四唑惊厥的保护作用

目的 :研究天麻对惊厥的保护作用。方法 :昆明种小鼠分为 3组 ,第 1组动物给予天麻混悬液灌胃 ,5 g·kg- 1,共 2次 ,间隔 3h ;第 2组给予同样剂量的天麻灌胃 ,每日 1次 ,连续 3d ;第 3组单次腹腔注射天麻水溶液制得的上清液 5 g·kg- 1,所有动物在最后一次天麻处理 30min后 ,腹腔注射戊四唑95mg·kg- 1诱发惊厥 ,观察 15min ,不出现强直性惊厥视为保护。小鼠大脑皮质制备的P 2组织用于氚标海人草酸 (2 0nmol·L- 1)结合实验。结果 :不同剂型天麻的预处理 ,对戊四唑致惊厥有不同的保护作用。第 1组的保护率为 5 5 % ,第 2组的保护率仅为 33% ;第 3组的保护率可达 86 %。天麻水溶液制得的上清液抑制氚标海人草酸结合 ,其IC50 值为10 .2mg·L- 1±s 0 .6mg·L- 1。结论 :结果表明不同剂型的天麻对戊四唑所致的强直性惊厥均有保护作用 ,至少有 1种抗惊厥有效成分是水溶性的     

四氢孕酮对小鼠不同惊厥模型的保护作用

目的观察四氢孕酮对不同动物惊厥模型的保护作用。方法C57小鼠腹腔注射四氢孕酮15min后观察其对最大电休克实验(maximalelectricalseizure,MES)或印防己所致惊厥的保护作用。结果在MES试验 ,四氢孕酮或苯巴比妥产生剂量依赖性的保护作用。苯巴比妥的ED50 为2.40mg·kg-1,95 %可信限为1.22至4.72mg·kg-1。四氢孕酮的ED50为0.086mg·kg-1,95 %可信限为0.037至0.201mg·kg-1,显著较苯巴比妥强 (P<0.01)。四氢孕酮对印防己所致惊厥保护作用的ED50为0.12mg·kg-1。两药各1/2ED50量的联合用药在MES试验产生80 %的保护作用 ,高于50 %。提示四氢孕酮和苯巴比妥具协同抗惊厥作用。在印防己致惊厥试验 ,四氢孕酮亦产生剂量依赖性保护作用 ,ED50 为0.123mg·kg-1,95 %可信限为0.085至0.263mg·kg-1。结论腹腔注射四氢孕酮对MES或印防己所致惊厥具有剂量依赖性的保护作用 ;对MES ,四氢孕酮的保护作用显著大于苯巴比妥 ,并与后者有协同作用。     

Arvanil,olvanil, AM 1172 and LY 2183240 (various cannabinoid CB1 receptor agonists) increase the threshold for maximal electroshock-induced seizures in mice

Background

Recent evidence reveals therapeutic potential for cannabinoids to reduce seizure frequency, severity and duration. Animal models are useful tools to determine the potential antiseizure or antiepileptic effects of cannabinoids. The objective of this study was evaluation of the effect of arvanil, olvanil, AM 1172 and LY 2183240, the compounds interacted with endocannabinoid and/or endovanilloid systems, on convulsions in the commonly used model of convulsions in mice.

Screening of the anticonvulsant activity of some plants from Fabaceae family in experimental seizure models in mice

BACKGROUND AND PURPOSE OF THE STUDY: Fabaceae is the third largest family of flowering plants. Lack of essential oils in the plants of this family can be an advantage in search for safe and effective medicines. In this study the anticonvulsant effect of the leaves of Albizzia julibrissin, Acacia juliflora, Acacia nubica and aerial parts of Astragalus obtusifolius was evaluated in pentylenetetrazole (PTZ) and maximal electroshock (MES) seizure tests. METHODS: The hydroalcoholic extracts of the plants were obtained by percolation. Different doses of the extracts were injected to the mice intraperitoneally (i.p.) and occurrence of clonic seizures induced by PTZ (60 mg/kg, i.p.) or tonic seizures induced by MES (50 mA, 50Hz, 1sec) were monitored up to 30 min after administration. Acute toxicity of the extracts was also assessed. The safe and effective extract was then fractionated by dichloromethane and anticonvulsant activity of the fractions was determined. Finally, the constituents of the extract and the fractions were screened by thin layer chromatography. RESULTS: Among the extracts, only A. obtusifolius extract showed low toxicity and protective effect against clonic seizures with ED50 value of 3.97 g/kg. Fractionation of the extract led to increase in anticonvulsant activity and ED50 value of 2.86 g/kg was obtained for the aqueous fraction. Phytochemical screening revealed the presence of alkaloids, flavonoids, anthrones and saponins in the aqueous fraction. MAJOR CONCLUSION: The presence of anticonvulsant compounds in A. obtusifolius suggests further activity-guided fractionation and analytical studies to find out the potential of this plant as a source of anticonvulsant agent.     

Effect of naproxen, a non-selective cyclo-oxygenase inhibitor, on pentylenetetrazol-induced kindling in mice

1. Epilepsy is one of the major neurological disorders of the brain, affecting approximately 0.5-1.0% of the population worldwide. Various neurotransmitter abnormalities, especially of GABA and glutamate, have been reported to play a key role in the pathophysiology of epilepsy. 2. Cyclo-oxygenase (COX) is the rate-limiting enzyme in the production of prostaglandins and, as such, is a key target for many anti-inflammatory drugs. Cyclo-oxygenase has been reported to play a significant role in neurodegeneration. Recent studies have reported that COX plays a significant role in the pathophysiology of epilepsy. 3. The aim of the present study was to explore the possible role of COX and the effect of COX inhibitors in epilepsy. 4. Kindling is a chronic model of epilepsy. In the present study, kindling was induced in mice by chronic administration of a subconvulsive dose of pentylenetetrazole (PTZ; 40 mg/kg) on every other day for a period of 15 days. Naproxen was administered daily 45 min before PTZ or vehicle. The kindling score was recorded after PTZ administration. Seizure severity was measured according to a prevalidated scoring scale. Biochemical estimations were performed immediately after recording behavioural parameters on the 16th day of PTZ treatment. 5. Chronic treatment with PTZ significantly induced kindling in mice. Pretreatment with the non-selective COX inhibitor naproxen (7 and 14 mg/kg, i.p.) showed significant protection against PTZ-induced kindling in mice. Biochemical analysis revealed that chronic treatment with PTZ significantly increased lipid peroxidation and nitrite levels (NO levels), but decreased reduced glutathione (GSH) levels in brain homogenates. 6. In conclusion, the results of the present study strongly suggest that COX plays an important role in the pathophysiology of PTZ-induced kindling in mice and that COX inhibitors could be a useful neuroprotective strategy for the treatment of epilepsy.     

Influence of propafenone on the anticonvulsant activity of various novel antiepileptic drugs in the mouse maximal electroshock model

Background

The main mechanism of action of propafenone (antiarrhythmic drug) involves the inhibition of the fast inward sodium current during phase 0 of the action potential. Sodium channel-blocking activity is also characteristic for some antiepileptic drugs. Therefore, it could be assumed that propafenone may also affect seizures. In the present study, we evaluated the effect of propafenone on the protective effect of oxcarbazepine, lamotrigine, topiramate and pregabalin against the maximal electroshock-induced seizures in mice.

Influence of ethacrynic acid on the anticonvulsant activity of conventional antiepileptic drugs in the mouse maximal electroshock seizure model

The aim of this study was to determine whether ethacrynic acid (EA), a loop diuretic with anticonvulsant activity, would affect the protective action of the conventional antiepileptics (AEDs) carbamazepine (CBZ), phenytoin (PHT), valproate (VPA) and phenobarbital (PB) in the mouse maximal electroshock seizure (MES) model. The effects of acute and chronic treatment with EA on these AEDs were examined. At a single dose of 100 mg/kg ip, EA enhanced the antielectroshock activity of VPA, decreasing its ED₅₀ value from 225.6 to 146.6 mg/kg (p < 0.05), but enhancement was not observed following continuous administration of EA (12.5 mg/kg) for seven days. Combined treatment of EA with other AEDs had no effect on their ED₅₀ values. The observed interaction between EA and VPA was pharmacodynamic in nature as EA did not alter free plasma (non-protein-bound) and total brain concentrations of VPA. Taking into consideration the clinical use of both drugs, this interaction between EA and VPA can be important for patients receiving these drugs.     

丹皮总甙抗实验性癫痫的研究

目的：了解丹皮总甙是否具有抗小鼠实验性癫痫作用。方法：采用最大电惊厥（ＭＥＳ）及戊四唑、士的宁、氨基脲等化学性惊厥模型，观察丹皮总甙（ｔｏｔａｌｇｌｕｃｏｓｉｄｅｓｏｆｍｏｕｔａｎｃｏｒｔｅｒ，ＴＧＭ）对动物惊厥发作数、发作潜伏期及动物存活时间等指标的影响，从而分析ＴＧＭ抗惊厥作用及其时量效关系。结果：ＴＧＭ（６０、８０ｍｇ·ｋｇ－１ｉｐ；８０ｍｇ·ｋｇ－１ｉｇ）可减少小鼠ＭＥＳ发作数，其峰时为药后０．５～１ｈ；ＴＧＭ（６０～８０ｍｇ·ｋｇ－１ｉｇ）可延长戊四唑、士的宁、氨基脲所致小鼠惊厥的潜伏期及动物存活时间；同时ＴＧＭ（４０ｍｇ·ｋｇ－１ｉｐ）可增强苯巴比妥抗上述惊厥之作用。结论：ＴＧＭ（６０～８０ｍｇ·ｋｇ－１）呈剂量依赖性对抗小鼠ＭＥＳ及戊四唑、士的宁、氨基脲所致小鼠化学性惊厥，并可增强苯巴比妥抗惊厥作用。     

Effects of sildenafil on pentylenetetrazol-induced convulsions in mice and amygdala-kindled seizures in rats

Sildenafil is the first marketed phosphodiesterase 5 inhibitor for the treatment of erectile dysfunction and recently, for pulmonary hypertension. While the treatment was found to be highly effective, several adverse effects are associated with this compound. Among numerous central nervous system-related untoward effects, proconvulsant activity was reported. The purpose of this study was to assess the effect of sildenafil on seizure threshold in rodents. Two seizure models/tests were used: the timed intravenous (iv) pentylenetetrazol (PTZ) infusion test in mice and the amygdala-kindling model in rats. Sildenafil was administered intraperitoneally 30 min before induction of seizures. In the iv PTZ paradigm, the first myoclonic twitch, generalized clonus with loss of the righting reflex, and forelimb tonus were recorded. In the amygdala-kindling model in rats, the following parameters were analyzed: threshold for induction of epileptiform discharges in the stimulated amygdala (afterdischarge threshold, ADT), seizure severity, seizure duration, and afterdischarge duration. Sildenafil (dosage range of 5–40 mg/kg) did not significantly affect the threshold for myoclonic twitches in the timed iv PTZ infusion test in mice but significantly decreased the threshold for clonic seizures at a dose of 20 mg/kg. Sildenafil at all doses tested neither significantly influenced the focal seizure threshold in the amygdala-kindling model of epilepsy in rats nor influenced seizure severity. Sildenafil significantly shortened afterdischarge duration and seizure duration recorded at the ADT current, indicative of a weak anticonvulsant activity. Our results show that sildenafil may have both pro- and anticonvulsant activity, which depends on the experimental model of epilepsy, on animal species and the dose of sildenafil. Based on these data and in view of the clinical observations, sildenafil should be used in patients suffering from epilepsy with caution and only based on a careful individual risk/benefit evaluation.