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We developed a focused series of original phenyl-glycinamide derivatives which showed potent activity across in vivo mouse seizure models, namely, maximal electroshock (MES) and 6 Hz (using both 32 and 44 mA current intensities) seizure models. Following intraperitoneal ( i.p .) administration, compound ( R )-32 , which was identified as a lead molecule, demonstrated potent protection against all seizure models with ED 50 values of 73.9 mg/kg (MES test), 18.8 mg/kg (6 Hz, 32 mA test), and 26.5 mg/kg (6 Hz, 44 mA test). Furthermore, ( R )-32 demonstrated efficacy in both the PTZ-induced kindling paradigm and the iv PTZ seizure threshold test. The expression of neurotrophic factors, such as mature brain-derived neurotrophic factor (mBDNF) and nerve growth factor (NGF), in the hippocampus and/or cortex of mice, and the levels of glutamate and GABA were normalized after PTZ-induced kindling by ( R )-32 . Importantly, besides antiseizure activity, ( R ) -32 demonstrated potent antinociceptive efficacy in formalin-induced pain, capsaicin-induced pain, as well as oxaliplatin- and streptozotocin-induced peripheral neuropathy in mice ( i.p .). No influence on muscular strength and body temperature in mice was observed. Pharmacokinetic studies and in vitro ADME-Tox data ( i.e. , high metabolic stability in human liver microsomes, a weak influence on CYPs, no hepatotoxicity, satisfactory passive transport, etc. ) proved favorable drug-like properties of ( R ) -32 . Thermal stability of ( R )- 32 shown in thermogravimetry and differential scanning calorimetry gives the opportunity to develop innovative oral solid dosage forms loaded with this compound. The in vitro binding and functional assays indicated its multimodal mechanism of action. ( R ) -32 , beyond TRPV1 antagonism, inhibited calcium and sodium currents at a concentration of 10 μM. Therefore, the data obtained in the current studies justify a more detailed preclinical development of ( R ) -32 for epilepsy and pain indications.

In the present study, a series of original alaninamide derivatives have been designed applying a combinatorial chemistry approach, synthesized, and characterized in the in vivo and in vitro assays. The obtained molecules showed potent and broad-spectrum activity in basic seizure models, namely, the maximal electroshock (MES) test, the 6 Hz (32 mA) seizure model, and notably, the 6 Hz (44 mA) model of pharmacoresistant seizures. Most potent compounds 26 and 28 displayed the following pharmacological values: ED 50 = 64.3 mg/kg (MES), ED 50 = 15.6 mg/kg (6 Hz, 32 mA), ED 50 = 29.9 mg/kg (6 Hz, 44 mA), and ED 50 = 34.9 mg/kg (MES), ED 50 = 12.1 mg/kg (6 Hz, 32 mA), ED 50 = 29.5 mg/kg (6 Hz, 44 mA), respectively. Additionally, 26 and 28 were effective in the iv PTZ seizure threshold test and had no influence on the grip strength. Moreover, lead compound 28 was tested in the PTZ-induced kindling model, and then, its influence on glutamate and GABA levels in the hippocampus and cortex was evaluated by the high-performance liquid chromatography (HPLC) method. In addition, 28 revealed potent efficacy in formalin-induced tonic pain, capsaicin-induced pain, and oxaliplatin- and streptozotocin-induced peripheral neuropathy. Pharmacokinetic studies and in vitro ADME-Tox data proved favorable drug-like properties of 28 . The patch-clamp recordings in rat cortical neurons showed that 28 at a concentration of 10 μM significantly inhibited fast sodium currents. Therefore, 28 seems to be an interesting candidate for future preclinical development in epilepsy and pain indications.

Previously, we demonstrated that palmatine (PALM) - an isoquinoline alkaloid from Berberis sibrica radix, exerted antiseizure activity in the pentylenetetrazole (PTZ)-induced seizure assay in larval zebrafish. The aim of the present study was to more precisely characterize PALM as a potential anticonvulsant drug candidate. A range of zebrafish and mouse seizure/epilepsy models were applied in the investigation. Immunostaining analysis was conducted to assess the changes in mouse brains, while in silico molecular modelling was performed to determine potential targets for PALM. Accordingly, PALM had anticonvulsant effect in ethyl 2-ketopent-4-enoate (EKP)-induced seizure assay in zebrafish larvae as well as in the 6 Hz-induced psychomotor seizure threshold and timed infusion PTZ tests in mice. The protective effect in the EKP-induced seizure assay was confirmed in the local field potential recordings. PALM did not affect seizures in the gabra1a knockout line of zebrafish larvae. In the scn1Lab -/- zebrafish line, pretreatment with PALM potentiated seizure-like behaviour of larvae. Repetitive treatment with PALM, however, did not reduce development of PTZ-induced seizure activity nor prevent the loss of parvalbumin-interneurons in the hippocampus of the PTZ kindled mice. In silico molecular modelling revealed that the noted anticonvulsant effect of PALM in EKP-induced seizure assay might result from its interactions with glutamic acid decarboxylase and/or via AMPA receptor non-competitive antagonism. Our study has demonstrated the anticonvulsant activity of PALM in some experimental models of seizures, including a model of pharmacoresistant seizures induced by EKP. These results indicate that PALM might be a suitable new drug candidate but the precise mechanism of its anticonvulsant activity has to be determined., Competing Interests: Declaration of Competing Interest The authors declare no conflict of interest., (Copyright © 2024 The Authors. Published by Elsevier Masson SAS.. All rights reserved.)

Traditionally, selected plant sources have been explored for medicines to treat convulsions. This continues today, especially in countries with low-income rates and poor medical systems. However, in the low-income countries, plant extracts and isolated drugs are in high demand due to their good safety profiles. Preclinical studies on animal models of seizures/epilepsy have revealed the anticonvulsant and/or antiepileptogenic properties of, at least some, herb preparations or plant metabolites. Still, there is a significant number of plants known in traditional medicine that exert anticonvulsant activity but have not been evaluated on animal models. Zebrafish is recognized as a suitable in vivo model of epilepsy research and is increasingly used as a screening platform. In this review, the results of selected preclinical studies are summarized to provide credible information for the future development of effective screening methods for plant-derived antiseizure/antiepileptic therapeutics using zebrafish models. We compared zebrafish vs. rodent data to show the translational value of the former in epilepsy research. We also surveyed caveats in methodology. Finally, we proposed a pipeline for screening new anticonvulsant plant-derived drugs in zebrafish ("from tank to bedside and back again")., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Knap, Nieoczym, Kundap, Kusio-Targonska, Kukula-Koch, Turski and Gawel.)

The aim of this study is to evaluate the anticonvulsant potential of schisandrin B, a main ingredient of Schisandra chinensis extracts. Schisandrin B showed anticonvulsant activity in the zebrafish larva pentylenetetrazole acute seizure assay but did not alter seizure thresholds in the intravenous pentylenetetrazole test in mice. Schisandrin B crosses the blood-brain barrier, which we confirmed in our in silico and in vivo analyses; however, the low level of its unbound fraction in the mouse brain tissue may explain the observed lack of anticonvulsant activity. Molecular docking revealed that the anticonvulsant activity of the compound in larval zebrafish might have been due to its binding to a benzodiazepine site within the GABA A receptor and/or the inhibition of the glutamate NMDA receptor. Although schisandrin B showed a beneficial anticonvulsant effect, toxicological studies revealed that it caused serious developmental impairment in zebrafish larvae, underscoring its teratogenic properties. Further detailed studies are needed to precisely identify the properties, pharmacological effects, and safety of schisandrin B.

In contrast to the other components of the medium-chain triglycerides ketogenic diet (MCT KD), i.e., caprylic acid (CA8), a comprehensive evaluation of caproic (CA6) and lauric acids' (CA12) properties in standard chemical and electrical seizure tests in mice has not yet been performed. We investigated their effects in maximal electroshock seizure threshold (MEST), 6 Hz seizure threshold and intravenous (i.v.) pentylenetetrazole (PTZ) seizure tests. Since ketone body production can be regulated by the activation of 5'AMP-activated protein kinase (AMPK), we hypothesized that metformin (an AMPK activator) enhance ketogenesis and would act synergistically with the fatty acids to inhibit convulsions. We assessed the effects of acute and chronic co-treatment with metformin and CA6/CA8 on seizures. CA6 and CA12 (p.o.) increased seizure threshold in the 6 Hz seizure test. CA6 at the highest tested dose (30 mmol/kg) developed toxicity in several mice, impaired motor performance and induced ketoacidosis. Acute and chronic co-treatment with metformin and CA6/CA8 did not affect seizure thresholds. Moreover, we observed the pro-convulsive effect of the acute co-administration of CA8 (5 mmol/kg) and metformin (100 mg/kg). Since this co-treatment was pro-convulsive, the safety profile and risk/benefit ratio of MCT KD and metformin concomitant therapy in epileptic patients should be further evaluated.

The pharmacological activation of the GPR39 receptor has been proposed as a novel strategy for treating seizures; however, this hypothesis has not been verified experimentally. TC-G 1008 is a small molecule agonist increasingly used to study GPR39 receptor function but has not been validated using gene knockout. Our aim was to assess whether TC-G 1008 produces anti-seizure/anti-epileptogenic effects in vivo and whether the effects are mediated by GPR39. To obtain this goal we utilized various animal models of seizures/epileptogenesis and GPR39 knockout mice model. Generally, TC-G 1008 exacerbated behavioral seizures. Furthermore, it increased the mean duration of local field potential recordings in response to pentylenetetrazole (PTZ) in zebrafish larvae. It facilitated the development of epileptogenesis in the PTZ-induced kindling model of epilepsy in mice. We demonstrated that TC-G 1008 aggravated PTZ-epileptogenesis by selectively acting at GPR39. However, a concomitant analysis of the downstream effects on the cyclic-AMP-response element binding protein in the hippocampus of GPR39 knockout mice suggested that the molecule also acts via other targets. Our data argue against GPR39 activation being a viable therapeutic strategy for treating epilepsy and suggest investigating whether TC-G 1008 is a selective agonist of the GPR39 receptor., (© 2023. The Author(s).)

The G-protein coupled receptor 39 (GPR39) is gaining increasing attention as a target for future drugs, yet there are gaps in the understanding of its pharmacology. Zinc is an endogenous agonist or an allosteric modulator, while TC-G 1008 is a synthetic, small molecule agonist. Zinc is also a positive allosteric modulator for the activity of TC-G 1008 at GPR39. Activation of GPR39 by TC-G 1008 facilitated the development of epileptogenesis in the pentylenetetrazole (PTZ)-induced kindling model of epilepsy. Congruently, TC-G 1008 decreased the seizure threshold in the maximal electroshock seizure threshold (MEST) test. Here, we investigated the effects of TC-G 1008 under the condition of zinc deficiency. Mice were fed a zinc-adequate diet (ZnA, 50 mg Zn/kg) or a zinc-deficient diet (ZnD, 3 mg Zn/kg) for 4 weeks. Following 4 weeks of dietary zinc restriction, TC-G 1008 was administered as a single dose and the MEST test was performed. Additional groups of mice began the PTZ-kindling model during which TC-G 1008 was administered repeatedly and the diet was continued. TC-G 1008 administered acutely decreased the seizure threshold in the MEST test in mice fed the ZnD diet but not in mice fed the ZnA diet. TC-G 1008 administered chronically increased the maximal seizure severity and the percentage of fully kindled mice in those fed the ZnA diet, but not in mice fed the ZnD diet. Our data showed that the amount of zinc in a diet is a factor contributing to the effects of TC-G 1008 in vivo.

( R )-7 [ ( R )-AS-1 ] showed broad-spectrum antiseizure activity across in vivo mouse seizure models: maximal electroshock (MES), 6 Hz (32/44 mA), acute pentylenetetrazol (PTZ), and PTZ-kindling. A remarkable separation between antiseizure activity and CNS-related adverse effects was also observed. In vitro studies with primary glia cultures and COS-7 cells expressing the glutamate transporter EAAT2 showed enhancement of glutamate uptake, revealing a stereoselective positive allosteric modulator (PAM) effect, further supported by molecular docking simulations. ( R )-7 [ ( R )-AS-1 ] was not active in EAAT1 and EAAT3 assays and did not show significant off-target activity, including interactions with targets reported for marketed antiseizure drugs, indicative of a novel and unprecedented mechanism of action. Both in vivo pharmacokinetic and in vitro absorption, distribution, metabolism, excretion, toxicity (ADME-Tox) profiles confirmed the favorable drug-like potential of the compound. Thus, ( R )-7 [ ( R )-AS-1 ] may be considered as the first-in-class small-molecule PAM of EAAT2 with potential for further preclinical and clinical development in epilepsy and possibly other CNS disorders.

Several ligands have been proposed for the GPR39 receptor, including the element zinc. The relationship between GPR39 and magnesium homeostasis has not yet been examined, nor has such a relationship in the context of seizures/epilepsy. We used samples from mice that were treated with an agonist of the GPR39 receptor (TC-G 1008) and underwent acute seizures (maximal electroshock (MES)- or 6-hertz-induced seizures) or a chronic, pentylenetetrazole (PTZ)-induced kindling model of epilepsy. MES seizures and PTZ kindling, unlike 6 Hz seizures, increased serum magnesium concentration. In turn, Gpr39 -KO mice that underwent PTZ kindling displayed decreased concentrations of this element in serum, compared to WT mice subjected to this procedure. However, the levels of expression of TRPM7 and SlC41A1 proteins-which are responsible for magnesium transport into and out of cells, respectively-did not differ in the hippocampus between Gpr39 -KO and WT mice. Furthermore, laser ablation inductively coupled plasma mass spectrometry applied to hippocampal slices did not reveal differences in magnesium levels between the groups. These data show the relationship between magnesium homeostasis and certain types of acute or chronic seizures (MES seizures or PTZ kindling, respectively), but do not explicitly support the role of GPR39 in mediating magnesium balance in the hippocampus in the latter model. However, decreased expression of TRPM7 and increased expression of SLC41A1-which were observed in the hippocampi of Gpr39 -KO mice treated with TC-G 1008, in comparison to WT mice that received the same treatment-implicitly support the link between GPR39 and hippocampal magnesium homeostasis.

In the present study, a focused combinatorial chemistry approach was applied to merge structural fragments of well-known TRPV1 antagonists with a potent anticonvulsant lead compound, KA-104 , that was previously discovered by our group. Consequently, a series of 22 original compounds has been designed, synthesized, and characterized in the in vivo and in vitro assays. The obtained compounds showed robust in vivo antiseizure activity in the maximal electroshock (MES) test and in the 6 Hz seizure model (using both 32 and 44 mA current intensities). The most potent compounds 53 and 60 displayed the following pharmacological profile: ED 50 = 89.7 mg/kg (MES), ED 50 = 29.9 mg/kg (6 Hz, 32 mA), ED 50 = 68.0 mg/kg (6 Hz, 44 mA), and ED 50 = 73.6 mg/kg (MES), ED 50 = 24.6 mg/kg (6 Hz, 32 mA), and ED 50 = 56.3 mg/kg (6 Hz, 44 mA), respectively. Additionally, 53 and 60 were effective in the iv PTZ seizure threshold and had no influence on the grip strength and body temperature in mice. The in vitro binding and functional assays indicated a multimodal mechanism of action for 53 and 60 . These molecules, beyond TRPV1 antagonism, inhibited calcium currents and fast sodium currents in patch-clamp assays. Further studies proved beneficial in vitro ADME-Tox properties for 53 and 60 (i.e., high metabolic stability, weak influence on CYPs, no neurotoxicity, etc.). Overall, 53 and 60 seem to be interesting candidates for future preclinical development in epilepsy and pain indications due to their interaction with the TRPV1 channel.

We report herein a series of water-soluble analogues of previously described anticonvulsants and their detailed in vivo and in vitro characterization. The majority of these compounds demonstrated broad-spectrum anticonvulsant properties in animal seizure models, including the maximal electroshock (MES) test, the pentylenetetrazole-induced seizure model ( sc PTZ), and the psychomotor 6 Hz (32 mA) seizure model in mice. Compound 14 showed the most robust anticonvulsant activity (ED 50 MES = 49.6 mg/kg, ED 50 6 Hz (32 mA) = 31.3 mg/kg, ED 50 sc PTZ = 67.4 mg/kg). Notably, it was also effective in the 6 Hz (44 mA) model of drug-resistant epilepsy (ED 50 = 63.2 mg/kg). Apart from favorable anticonvulsant properties, compound 14 revealed a high efficacy against pain responses in the formalin-induced tonic pain, the capsaicin-induced neurogenic pain, as well as in the oxaliplatin-induced neuropathic pain in mice. Moreover, compound 14 showed distinct anti-inflammatory activity in the model of carrageenan-induced aseptic inflammation. The mechanism of action of compound 14 is likely complex and may result from the inhibition of peripheral and central sodium and calcium currents, as well as the TRPV1 receptor antagonism as observed in the in vitro studies. This lead compound also revealed beneficial in vitro ADME-Tox properties and an in vivo pharmacokinetic profile, making it a potential candidate for future preclinical development. Interestingly, the in vitro studies also showed a favorable induction effect of compound 14 on the viability of neuroblastoma SH-SY5Y cells.

Experimental studies have demonstrated that general anesthetics administered during the period of synaptogenesis may induce widespread neurodegeneration, which results in permanent cognitive and behavioral deficits. What remains to be elucidated is the extent of the potential influence of the commonly used hypnotics on comorbidities including epilepsy, which may have resulted from increased neurodegeneration during synaptogenesis. This study aimed to test the hypothesis that neuropathological changes induced by anesthetics during synaptogenesis may lead to changes in the seizure threshold during adulthood. Wistar rat pups were treated with propofol, sevoflurane, or saline on the sixth postnatal day. The long-term effects of prolonged propofol and sevoflurane anesthesia on epileptogenesis were assessed using corneal kindling, pilocarpine-, and pentylenetetrazole-induced seizure models in adult animals. Body weight gain was measured throughout the experiment. No changes in the seizure threshold were observed in the three models. A significant weight gain after exposure to anesthetics during synaptogenesis was observed in the propofol group but not in the sevoflurane group. The results suggest that single prolonged exposure to sevoflurane or propofol during synaptogenesis may have no undesirable effects on epileptogenesis in adulthood.

Rationale: Pterostilbene is the 3,5-dimethoxy derivative of resveratrol with numerous beneficial effects including neuroprotective properties. Experimental studies revealed its anticonvulsant action in the acute seizure tests., Objectives: The purpose of the present study was to evaluate the effect of pterostilbene in the pentetrazol (PTZ)-induced kindling model of epilepsy in mice as well as to assess some possible mechanisms of its anticonvulsant action in this model., Methods: Mice were repeatedly treated with pterostilbene (50-200 mg/kg) and its effect on the development of seizure activity in the PTZ kindling was estimated. Influence of pterostilbene on the locomotor activity and anxiety- and depression-like behavior in the PTZ-kindled mice was also assessed. To understand the possible mechanisms of anticonvulsant activity of pterostilbene, γ-aminobutyric acid (GABA) and glutamate concentrations in the prefrontal cortex and hippocampus of the PTZ-kindled mice were measured using LC-MS/MS method. Moreover, mRNA expression of BDNF, TNF-α, IL-1β, IL-6, GABRA1A, and GRIN2B was determined by RT-qPCR technique., Results: We found that pterostilbene at a dose of 200 mg/kg considerably reduced seizure activity but did not influence the locomotor activity and depression- and anxiety-like behavior in the PTZ-kindled mice. In the prefrontal cortex and hippocampus, pterostilbene reversed the kindling-induced decrease of GABA concentration. Neither in the prefrontal cortex nor hippocampus pterostilbene affected mRNA expression of IL-1β, IL-6, GABRA1A, and GRIN2B augmented by PTZ kindling. Pterostilbene at a dose of 100 mg/kg significantly decreased BDNF and TNF-α mRNA expression in the hippocampus of the PTZ-kindled mice., Conclusions: Although further studies are necessary to understand the mechanism of anticonvulsant properties of pterostilbene, our findings suggest that it might be considered a candidate for a new antiseizure drug., (© 2021. The Author(s).)

Zingiber officinale is one of the most frequently used medicinal herbs in Asia. Using rodent seizure models, it was previously shown that Zingiber officinale hydroethanolic extract exerts antiseizure activity, but the active constituents responsible for this effect have not been determined. In this paper, we demonstrated that Zingiber officinale methanolic extract exerts anticonvulsant activity in the pentylenetetrazole (PTZ)-induced hyperlocomotion assay in larval zebrafish. Next, we isolated 6-gingerol (6-GIN)-a major constituent of Zingiber officinale rhizoma . We observed that 6-GIN exerted potent dose-dependent anticonvulsant activity in the PTZ-induced hyperlocomotion seizure assay in zebrafish, which was confirmed electroencephalographically. To obtain further insight into the molecular mechanisms of 6-GIN antiseizure activity, we assessed the concentration of two neurotransmitters in zebrafish, i.e., inhibitory γ-aminobutyric acid (GABA) and excitatory glutamic acid (GLU), and their ratio after exposure to acute PTZ dose. Here, 6-GIN decreased GLU level and reduced the GLU/GABA ratio in PTZ-treated fish compared with only PTZ-bathed fish. This activity was associated with the decrease in grin2b , but not gabra1a , grin1a , gria1a , gria2a , and gria3b expression in PTZ-treated fish. Molecular docking to the human NR2B-containing N-methyl-D-aspartate (NMDA) receptor suggests that 6-GIN might act as an inhibitor and interact with the amino terminal domain, the glutamate-binding site, as well as within the ion channel of the NR2B-containing NMDA receptor. In summary, our study reveals, for the first time, the anticonvulsant activity of 6-GIN. We suggest that this effect might at least be partially mediated by restoring the balance between GABA and GLU in the epileptic brain; however, more studies are needed to prove our hypothesis.

Palmatine (PALM) and berberine (BERB) are widely identified isoquinoline alkaloids among the representatives of the Berberidaceae botanical family. The antiseizure activity of BERB was shown previously in experimental epilepsy models. We assessed the effect of PALM in a pentylenetetrazole (PTZ)-induced seizure assay in zebrafish, with BERB as an active reference compound. Both alkaloids were isolated from the methanolic root extract of Berberis sibirica by counter-current chromatography, and their ability to cross the blood-brain barrier was determined via quantitative structure-activity relationship assay. PALM exerted antiseizure activity, as confirmed by electroencephalographic analysis, and decreased c-fos and bdnf levels in PTZ-treated larvae. In a behavioral assay, PALM dose-dependently decreased PTZ-induced hyperlocomotion. The combination of PALM and BERB in ED 16 doses revealed hyperadditive activity towards PTZ-induced hyperlocomotion. Notably, we have indicated that both alkaloids may exert their anticonvulsant activity through different mechanisms of action. Additionally, the combination of both alkaloids in a 1:2.17 ratio (PALM: BERB) mimicked the activity of the pure extract, which indicates that these two active compounds are responsible for its anticonvulsive activity. In conclusion, our study reveals for the first time the anticonvulsant activity of PALM and suggests the combination of PALM and BERB may have higher therapeutic value than separate usage of these compounds.

In our recent studies, we identified compound N-benzyl-2-(2,5-dioxopyrrolidin-1-yl)propanamide (AS-1) as a broad-spectrum hybrid anticonvulsant which showed potent protection across the most important animal acute seizure models such as the maximal electroshock (MES) test, the subcutaneous pentylenetetrazole (s.c. PTZ) test, and the 6-Hz (32 mA) test in mice. Therefore, AS-1 may be recognized as a candidate for new anticonvulsant effective in different types of human epilepsy with a favorable safety margin profile determined in the rotarod test in mice. In the aim of further pharmacological evaluation of AS-1, in the current study, we examined its activity in the 6-Hz (44 mA) test, which is known as the model of drug-resistant epilepsy. Furthermore, we determined also the antiseizure activity in the kindling model of epilepsy induced by repeated injection of pentylenetetrazole (PTZ) in mice. As a result, AS-1 revealed relatively potent protection in the 6-Hz (44 mA) test, as well as delayed the progression of kindling induced by repeated injection of PTZ in mice at doses of 15 mg/kg, 30 mg/kg, and 60 mg/kg. Importantly, the isobolographic analysis showed that a combination of AS-1 and valproic acid (VPA) at the fixed ratio of 1:1 displayed a supra-additive (synergistic) interaction against PTZ-induced seizures in mice. Thus, AS-1 may be potentially used in an add-on therapy with VPA. Moreover, incubation of zebrafish larvae with AS-1 substantially decreased the number, cumulative but not the mean duration of epileptiform-like events in electroencephalographic assay. Finally, the in vitro ADME-Tox studies revealed that AS-1 is characterized by a very good permeability in the parallel artificial membrane permeability assay test, excellent metabolic stability on human liver microsomes (HLMs), no significant influence on CYP3A4/CYP2D6 activity, and moderate inhibition of CYP2C9 in a concentration of 10 μM, as well as no hepatotoxic properties in HepG2 cells (concentration of 10 μM).

Pterostilbene (PTE), a natural analog of resveratrol, is available both as a diet ingredient and a dietary supplement. The present study was undertaken to assess the effect of PTE on the activity of antiepileptic drugs in the acute seizure tests in mice, i.e., the intravenous pentetrazole (iv PTZ) seizure threshold, maximal electroshock (MES), and 6 Hz-induced psychomotor seizure tests. Our study revealed that PTE enhanced the anticonvulsant effect of clonazepam but did not change the activity of tiagabine in the iv PTZ test. In the MES test, PTE increased the effect of carbamazepine but did not affect the protective properties of topiramate, while in the 6-Hz test, we noted a significant enhancement of the activity of oxcarbazepine, but there were no changes in the activity of valproate. Interactions of PTE with carbamazepine and oxcarbazepine were pharmacokinetic, which was determined by the increase of concentration of these antiepileptic drugs both in the serum and brain. In contrast, interactions between PTE and clonazepam were pharmacodynamic since there were no changes in the concentration of clonazepam. Combined treatment with carbamazepine and PTE significantly attenuated muscular strength (estimated in the grip strength test) but did not change motor coordination (assessed in the chimney test) in mice. Other studied antiepileptic drugs and their combinations with PTE did not change these parameters. Further studies are required to evaluate the influence of PTE on the activity of anticonvulsant drugs to estimate the safety of using PTE by patients with epilepsy.

Cannabidiol and cannabidiol-enriched products have recently attracted much attention as an add-on therapy for epilepsy, especially drug-resistant seizures. It should be, however, remembered that concomitant use of cannabidiol and antiepileptic drugs may pose a risk of interactions between them. For this reason, the aim of our study was to assess the effect of cannabidiol on the activity of selected new antiepileptic drugs in the electrically-induced seizure models in mice. We studied the effect of cannabidiol on the anticonvulsant action of topiramate, oxcarbazepine, lamotrigine, and pregabalin in the maximal electroshock-induced seizure test as well as on the activity of levetiracetam, tiagabine, lacosamide, and gabapentin in the 6 Hz seizure test in mice. We showed that cannabidiol increased the activity of topiramate, oxcarbazepine, pregabalin, tiagabine, and gabapentin. It did not affect the anticonvulsant effect of lamotrigine and lacosamide. Interestingly, cannabidiol attenuated the anticonvulsant activity of levetiracetam. Co-administration of antiepileptic drugs with cannabidiol did not cause adverse effects such as impairment of motor coordination, changes in neuromuscular strength or potentiation of the cannabidiol-induced hypolocomotion. Serum and brain levels of antiepileptic drugs and cannabidiol were determined by using HPLC in order to ascertain any pharmacokinetic contribution to the observed behavioral effects. Only interaction with levetiracetam was purely pharmacodynamic in nature because no changes in serum and brain concentration of either levetiracetam or cannabidiol were observed. Increased anticonvulsant activity of topiramate, oxcarbazepine, pregabalin, tiagabine, and gabapentin could be, at least in part, related to pharmacokinetic interactions with cannabidiol because there were changes in serum and/or brain concentrations of antiepileptic drugs and/or cannabidiol. Pharmacokinetic interactions cannot be also excluded between lacosamide and cannabidiol because cannabidiol increased brain concentration of lacosamide and lacosamide increased brain concentration of cannabidiol. Further pharmacokinetic studies are required to evaluate the type of interactions between cannabidiol and novel antiepileptic drugs., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Pterostilbene (PTE), a natural dimethylated analog of resveratrol, possesses numerous health-beneficial properties. The ability of PTE to cross the blood-brain barrier raised the possibility that this compound may modulate central nervous system functions, including seizure activity. The aim of our study was to investigate the activity of PTE in the larval zebrafish pentylenetetrazole (PTZ) seizure assay and three acute seizure tests in mice, i.e., in the maximal electroshock seizure threshold (MEST), 6 Hz-induced psychomotor seizure threshold and intravenous (iv) PTZ tests. Additionally, potential antidepressant activity of PTE was estimated in the forced swim test in mice. The chimney test was used to determine the influence of PTE on motor coordination in mice, while its influence on neuromuscular strength was assessed in the grip strength test in mice. Locomotor activity was determined to verify the results from the forced swim test. PTE revealed an evident anticonvulsant effect both in zebrafish larvae (10 µM; 2 h-incubation) and mice (at doses of 100 and 200 mg/kg, intraperitoneally) but it did not exhibit antidepressant potential in the forced swim test. Furthermore, it did not cause any statistically significant changes in motor coordination, neuromuscular strength and locomotor activity in mice. In conclusion, our present findings demonstrate for the first time the anticonvulsant potential of PTE. The aforementioned results suggest that it might be employed in epilepsy treatment, however, further precise studies are required to verify its activity in other experimental seizure and epilepsy models and its precise mechanism of action should be determined.

Recently, compound KA-11 was identified as a promising candidate for a new broad-spectrum anticonvulsant. This compound revealed wide protective activity across the most important animal models of seizures such as the maximal electroshock test (MES), the subcutaneous pentylenetetrazole test ( scPTZ), and the six-hertz test (6 Hz, 32 mA). Importantly, KA-11 was devoid of acute neurological activity, which was assessed by applying the chimney test (TD 50 value higher than 1500 mg/kg). The preliminary in vivo results confirmed favorable anticonvulsant and safety properties of KA-11. With the aim of further biological characterization of KA-11, in the current studies we evaluated its antiepileptogenic activity in the kindling model of epilepsy induced by repeated injection of PTZ in mice. Furthermore, we assessed the antinociceptive activity of KA-11 in several animal pain models. As a result, KA-11 (at all doses applied: 25, 50, and 100 mg/kg) significantly delayed the progression of kindling induced by repeated injection of PTZ in mice. Additionally, KA-11 revealed potent antinociceptive activity in the formalin-induced tonic pain and, importantly, in the oxaliplatin-induced neuropathic pain model in mice. Moreover, KA-11 did not induce motor deficits in the rotarod test. Patch-clamp experiments revealed that one of the mechanisms of action of KA-11 is inhibition of voltage-gated sodium currents. Compound KA-11 appeared to be safe in relation to hepatotoxic properties as no phospholipidosis induction was determined in HepG2 cells at 50 μM, and a small, statistically significant decrease of cell viability was observed only at the highest used dose of 100 μM. Moreover, KA-11 did not affect the function of CYP2D6. The aforementioned hybrid substance proved to penetrate the biological membranes in the in vitro permeability assays.

Sildenafil influences seizure activity in animal seizure models, and its both proconvulsant and anticonvulsant effects were reported. We previously found that this PDE5 inhibitor significantly increased seizure threshold for the 6 Hz-induced psychomotor seizures in mice and therefore we aimed to investigate the influence of some modulators of neurotransmitter receptors, i.e., diazepam (GABA/benzodiazepine receptor agonist), flumazenil (GABA/benzodiazepine receptor antagonist), N-methyl-d-aspartic acid (NMDA glutamate receptor agonist), CGP 37849 (NMDA receptor antagonist), metergoline (serotonin receptor antagonist), 8-cyclopentyl-1,3-dipropylxanthine (adenosine A 1 receptor antagonist) and β-funaltrexamine (μ opioid receptor antagonist), on the anticonvulsant effect of sildenafil in this test. Additionally, we estimated influence of the studied compounds and their combinations with sildenafil on the muscular strength (assessed in the grip strength test) and motor coordination (assessed in the chimney test) in mice. Our results indicate that anticonvulsant properties of sildenafil in the 6 Hz test in mice might be related to its interactions with the GABAergic, glutamatergic, serotonergic and adenosinergic neurotransmission. We did not find interactions between sildenafil and μ opioid receptors. Neither the studied ligands nor their combinations with sildenafil impaired muscular strength and motor coordination. In conclusion, sildenafil has complex and extensive influence on neurotransmission and seizure generation in the CNS., (Copyright © 2018 Elsevier Masson SAS. All rights reserved.)

Tadalafil, a selective phosphodiesterase type 5 inhibitor, is a long-acting oral agent for the treatment of erectile dysfunction of multiple etiologies. Although generalized tonic-clonic seizures were reported in a healthy man after taking tadalafil, the influence of tadalafil on seizure susceptibility has not been studied so far. Therefore, the aim of the present study was to investigate the effect of tadalafil on seizure threshold as well as on the activity of some first- and second-generation antiepileptic drugs in three acute seizure tests in mice. The obtained results showed that tadalafil, at the highest dose tested (20 mg/kg), significantly decreased the threshold for the first myoclonic twitch in the intravenous pentylenetetrazole (i.v. PTZ) seizure test. It did not affect the threshold for generalized clonic seizure and forelimb tonus in the i.v. PTZ, for tonic hindlimb extension in the maximal electroshock seizure threshold test, and for psychomotor seizure in the 6-Hz-induced seizure threshold test. Tadalafil did not alter the anticonvulsant activity of any of the studied antiepileptic drugs in electrically induced seizure tests. Interestingly, tadalafil potentiated the anticonvulsant activity of clonazepam and decreased the anticonvulsant activity of oxcarbazepine in the i.v. PTZ test. These interactions were pharmacodynamic in nature, as tadalafil did not alter clonazepam and oxcarbazepine concentrations both in serum and brain tissue. Furthermore, neither tadalafil alone nor its combinations with the studied antiepileptic drugs produced any significant impairment of motor coordination (assessed in the chimney test), muscular strength (investigated in the grip-strength test), and long-term memory (assessed in the passive avoidance task). In conclusion, tadalafil may increase the risk of myoclonic seizure and decrease the anticonvulsant efficacy of oxcarbazepine. Further studies are warranted to evaluate the safety of tadalafil usage in patients with epilepsy.

Ursolic acid (UA) is a plant derived compound which is also a component of the standard human diet. It possesses a wide range of pharmacological properties, i.e., antioxidant, anti-inflammatory, antimicrobial and antitumor, which have been used in folk medicine for centuries. Moreover, influence of UA on central nervous system-related processes, i.e., pain, anxiety and depression, was proved in experimental studies. UA also revealed anticonvulsant properties in animal models of epilepsy and seizures. The aim of the present study was to investigate the influence of UA on seizure thresholds in three acute seizure models in mice, i.e., the 6 Hz-induced psychomotor seizure threshold test, the maximal electroshock threshold (MEST) test and the timed intravenous pentylenetetrazole (iv PTZ) infusion test. We also examined its effect on the muscular strength (assessed in the grip strength test) and motor coordination (estimated in the chimney test) in mice. UA at doses of 50 and 100 mg/kg significantly increased the seizure thresholds in the 6 Hz and MEST tests. The studied compound did not influence the seizure thresholds in the iv PTZ test. Moreover, UA did not affect the motor coordination and muscular strength in mice. UA displays only a weak anticonvulsant potential which is dependent on the used seizure model.

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

Most antidepressants lower seizure threshold, which might be due to the modulation of serotonergic neurotransmission. Here, we investigated the effects of two 5-HT 1A , 5-HT 7 and 5-HT 3 antagonists, i.e., 1-(2-(2-(2,6-dimethylphenoxy)ethoxy)ethyl)-4-(2-methoxyphenyl)piperazine hydrochloride (HBK-14) and 1-{2-[2-(2-chloro-6-methylphenoxy)ethoxy]ethyl}-4-(2-methoxyphenyl)piperazine hydrochloride (HBK-15), with antidepressant- and anxiolytic-like properties, on seizure thresholds in three acute seizure tests, i.e., the intravenous pentylenetetrazole, maximal electroshock seizure threshold (MEST), and 6-Hz corneal stimulation test in mice. We also evaluated their affinity for voltage-gated sodium channels. Our results indicate that HBK-14 increased seizure thresholds in three seizure tests in mice, while HBK-15 was active in the MEST and 6-Hz tests. None of the compounds affected neuromuscular strength or motor coordination at active doses. We showed that both compounds had high affinity for voltage-dependent sodium channels, which combined with the influence on 5-HT 1A , 5-HT 7 and 5-HT 3 receptors, might underlie their anticonvulsant effects. Since most antidepressants lower the seizure threshold, the fact that both compounds with potent antidepressant-like activity, increased or had no influence on seizure threshold is worth investigating., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Activation of Nrf2 with sulforaphane has recently gained attention as a new therapeutic approach in the treatment of many diseases, including epilepsy. As a plant-derived compound, sulforaphane is considered to be safe and well-tolerated. It is widely consumed, also by patients suffering from seizure and taking antiepileptic drugs, but no toxicity profile of sulforaphane exists. Since many natural remedies and dietary supplements may increase seizure risk and potentially interact with antiepileptic drugs, the aim of our study was to investigate the acute effects of sulforaphane on seizure thresholds and activity of some first- and second-generation antiepileptic drugs in mice. In addition, some preliminary toxicity profile of sulforaphane in mice after intraperitoneal injection was evaluated. The LD 50 value of sulforaphane in mice was estimated at 212.67mg/kg, while the TD 50 value - at 191.58mg/kg. In seizure tests, sulforaphane at the highest dose tested (200mg/kg) significantly decreased the thresholds for the onset of the first myoclonic twitch and generalized clonic seizure in the iv PTZ test as well as the threshold for the 6Hz-induced psychomotor seizure. At doses of 10-200mg/kg, sulforaphane did not affect the threshold for the iv PTZ-induced forelimb tonus or the threshold for maximal electroshock-induced hindlimb tonus. Interestingly, sulforaphane (at 100mg/kg) potentiated the anticonvulsant efficacy of carbamazepine in the maximal electroshock seizure test. This interaction could have been pharmacokinetic in nature, as sulforaphane increased concentrations of carbamazepine in both serum and brain tissue. The toxicity study showed that high doses of sulforaphane produced marked sedation (at 150-300mg/kg), hypothermia (at 150-300mg/kg), impairment of motor coordination (at 200-300mg/kg), decrease in skeletal muscle strength (at 250-300mg/kg), and deaths (at 200-300mg/kg). Moreover, blood analysis showed leucopenia in mice injected with sulforaphane at 200mg/kg. In conclusion, since sulforaphane was proconvulsant at a toxic dose, the safety profile and the risk-to-benefit ratio of sulforaphane usage in epileptic patients should be further evaluated., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Sildenafil, a potent and selective inhibitor of phosphodiesterase type 5, is used clinically to treat erectile dysfunction and pulmonary arterial hypertension. It is often taken by patients suffering from depression and receiving antidepressant drug treatment. However, its influence on the efficacy of antidepressant treatment was not sufficiently studied. Therefore, the aim of the present study was to investigate the influence of sildenafil on the anti-immobility action of several antidepressant drugs (i.e., sertraline, fluvoxamine, citalopram, maprotiline, trazodone, and agomelatine) as well as on antidepressant-like effect of electroconvulsive stimulations in the forced swim test in mice. The obtained results showed that acute sildenafil treatment enhanced the antidepressant-like activity of all of the studied drugs. The observed effects were not due to the increase in locomotor activity. The interactions between sildenafil and sertraline, maprotiline, and trazodone were pharmacodynamic in nature, as sildenafil did not affect concentrations of these drugs neither in serum nor in brain tissue. Increased concentrations of fluvoxamine, citalopram, and agomelatine in brain tissue evoked by sildenafil co-administration suggest that pharmacokinetic interactions between sildenafil and these drugs are very likely. Sildenafil injected acutely did not alter the antidepressant-like efficacy of electroconvulsive stimulations in mice, as assessed in the forced swim test. Interestingly, repeated (14 days) administration of sildenafil decreased the anti-immobility action of the electroconvulsive stimulations. In conclusion, the present study shows that sildenafil may alter the effectiveness of antidepressant treatment. Further studies are warranted to better characterize the influence of sildenafil on the activity of antidepressant drugs and electroconvulsive therapy.

Sildenafil is a highly effective oral agent for the treatment of erectile dysfunction of multiple etiologies. Although in clinical practice sildenafil is often used in depressed patients, its influence on the pathophysiology of depression remains unclear. The aim of the present study was to evaluate the antidepressant-like activity following acute and subchronic treatment with sildenafil in naïve mice as well as in mice with reserpine- and restraint stress-induced depressive-like behavior. Since corticosterone is released in response to acute stress, we also aimed to assess the influence of sildenafil on serum corticosterone level in non-stressed and stressed animals. The antidepressant activity of sildenafil was assessed in the forced swim test. Corticosterone serum level was determined by using ELISA method, while brain and serum sildenafil level via HPLC method. Sildenafil administered acutely exerted an antidepressant-like effect. Subchronic (14 days) administration of sildenafil resulted only in a weak antidepressant-like effect when evaluated 24 h after the last dose. Acute but not subchronic sildenafil administration reversed the reserpine- and stress-induced immobility in the forced swim test. The lack of effects of sildenafil after subchronic treatment could have been related to its complete elimination from the brain within 24 h from the last injection. Interestingly, acute administration of sildenafil produced a marked increase in serum corticosterone level in both non-stressed and stressed animals. Sildenafil exerts differential effects in the forced swim test after acute and subchronic administration. Further studies on the antidepressant activity of sildenafil are required., Competing Interests: The authors declare no conflict of interest.

The anticonvulsant activity of melatonin (MLT) have been tested in several in vivo models and against different convulsive stimuli. Although MLT exerts high affinity towards melatonin receptors (MTs), the potential usefulness in the treatment of epilepsy is limited mainly due to its short half-life. Therefore, the purpose of the present study was to compare the anticonvulsant properties of novel MT agonists Neu-P11 and Neu-P67 with MLT in mice. The anticonvulsant activity of tested compounds was evaluated in pentylenetetrazole-(PTZ) and electrically-induced convulsions. The effect of studied compounds on motor coordination and skeletal muscular strength in mice was assessed in the chimney test and grip test, respectively. The locomotor activity after administration of the tested compounds was also evaluated. In the MEST and 6Hz tests, only MLT (50 and 100mg/kg, i.p.) significantly increased the seizure threshold. The i.p. administration of MLT (100mg/kg) and Neu-P67 (200mg/kg) resulted in a significantly elevated PTZ seizure threshold for forelimbs tonus. The compounds did not affect muscle strength. No alterations in motor coordination were noted. However, the locomotor activity was significantly decreased after administration of all tested compounds. Our study confirms the anticonvulsant potency of MLT and shows that novel synthetic MT agonists Neu-P11 and Neu-P67 have no effect on epileptic seizures in mice. Our data suggest that the activation of MT can be used in the treatment of seizures, but further pharmacological characterization is needed to understand the anticonvulsant activity of MLT and to design efficient MT-targeting antiepileptic drugs., (Copyright © 2016 Elsevier B.V. All rights reserved.)

This study evaluates the neuropharmacological effects of the aqueous extract of the Mexican plant Calea zacatechichi Schltdl., which is commonly used in folk medicine to treat cough, asthma, and gastrointestinal disorders. Moreover, it has been used for centuries in traditional rituals based on divination and is thought to possess hallucinogenic activity. To test the neuropharmacological effects of the aqueous extract of C. zacatechichi we used mouse models of convulsions, an elevated plus-maze test and measured locomotor activity. We also evaluated the effect of the extract on antidepressant-like behavior in forced swim test, as well as on muscular strength in a grip test. Moreover the antinociceptive action of the extract was evaluated in the hot-plate and writhing tests. The chemical composition of the extract was evaluated using LC-MS techniques. The aqueous extract of C. zacatechichi did not affect any of the parameters measured in seizure models. It had also no influence on anxiety, exploratory behavior and muscular strength in the applied doses. On the other hand, the extract exhibited antinociceptive effect in the mouse model of abdominal pain. Chemical characterization of the extract showed the presence of chlorogenic acid, acacetin, and germacranolides. Based on this report we suggest that aqueous extract of C. zacatechichi has insignificant neuropharmacological effects in vivo and reduces abdominal pain perception. Our results, together with previous studies showing beneficial effects of the extracts obtained from C. zacatechichi suggest that these preparations may be used to treat medical conditions.

α-Spinasterol is a plant-derived compound which was reported to act as a selective antagonist for the transient receptor potential vanilloid 1 (TRPV1) receptor. Several studies revealed that the TRPV1 receptors might modulate seizure activity in animal models of seizures and epilepsy. The aim of the present study was to investigate the effect of α-spinasterol on the seizure threshold in three acute models of seizures, i.e., in the intravenous (i.v.) pentylenetetrazole (PTZ) seizure test, in the maximal electroshock seizure threshold (MEST) test and in the model of psychomotor seizures induced by 6 Hz stimulation in mice. Our results revealed significant anticonvulsant effect of α-spinasterol in all the used seizure tests. In the i.v. PTZ test, statistically significant elevation was noted in case of the threshold for myoclonic twitches (doses of 0.1-1 mg/kg) and generalized clonus seizures (doses of 0.5 and 1 mg/kg) but not for tonic seizures. The studied TRPV1 antagonist also increased the threshold for tonic hindlimb extension in the MEST (doses of 0.5 and 1 mg/kg) and 6 Hz psychomotor seizure (doses of 0.1 and 0.5 mg/kg) tests in mice. Furthermore, α-spinasterol did not produce any significant impairment of motor coordination (assessed in the chimney test) and muscular strength (investigated in the grip-strength test) and it did not provoke significant changes in body temperature in mice. Based on the results of our study and the fact that α-spinasterol is characterized by good blood-brain permeability, we postulate further investigation of this compound to precisely evaluate mechanism of its anticonvulsant action and opportunity of its usage in clinical practice.

Capric acid (CA10) is a 10-carbon medium-chain fatty acid abundant in the medium-chain triglyceride ketogenic diet (MCT KD). The purpose of this study was to characterize acute anticonvulsant effects of CA10 across several seizure tests in mice. Anticonvulsant effects of orally (p.o.) administered CA10 were assessed in the maximal electroshock seizure threshold (MEST), 6-Hz seizure threshold, and intravenous pentylenetetrazole (i.v. PTZ) seizure tests in mice. Acute effects of CA10 on motor coordination were assessed in the grip and chimney tests. Plasma and brain concentrations of CA10 were measured. Co-administration studies with CA10 and another abundant medium-chain fatty acid, caprylic acid (CA8) were performed. CA10 showed significant and dose-dependent anticonvulsant properties by increasing seizure thresholds in the 6-Hz and MEST seizure tests; it was ineffective in the i.v. PTZ seizure test. At higher doses than those effective in the 6-Hz and MEST seizure tests, CA10 impaired motor performance in the grip and chimney tests. An enhanced anticonvulsant response in the 6-Hz seizure test was produced when CA8 and CA10 were co-administered. An acute p.o. administration of CA10 resulted in dose-proportional increases in its plasma and brain concentrations. CA10 exerted acute anticonvulsant effects at doses that produce plasma exposures comparable to those reported in epileptic patients on the MCT KD. An enhanced anticonvulsant effect is observed when CA10 and the other main constituent of the MCT KD, CA8, were co-administered. Thus, acute anticonvulsant properties of CA10 and CA8 may influence the overall clinical efficacy of the MCT KD., (Copyright © 2014. Published by Elsevier Inc.)

Although several studies have reported the acute anticonvulsant activity of caprylic acid in animal seizure models, little is known about the mechanism underlying this effect. Recently, the role of adenosine in the efficacy of the ketogenic diet has been postulated. Therefore, the present study aimed to evaluate the possible involvement of the adenosine system (in non-fasted mice) as well as the role of glucose restriction (in fasted and non-fasted mice) in the acute anticonvulsant activity of caprylic acid in the 6 Hz psychomotor seizure threshold test. We showed that the anticonvulsant effect of caprylic acid (30 mmol/kg, p.o.) was reversed by a selective adenosine A1 receptor antagonist (DPCPX, 1mg/kg, i.p.) and a selective adenosine A2A receptor antagonist (KW-6002, 1 mg/kg, p.o.) but not by glibenclamide (1 pg/mouse, i.c.v.) - the ATP-sensitive potassium (KATP) channel blocker. Co-administration of an ineffective dose of caprylic acid (20 mmol/kg) with an ineffective dose of adenosine transporter inhibitor (dipyridamole, 50 mg/kg, i.p.) significantly raised the threshold for the 6 Hz-induced seizures. A high dose of glucose (2 g/kg) significantly only diminished the anticonvulsant effect of caprylic acid (30 mmol/kg) in non-fasted mice, and this was accompanied by an increase in blood glucose level and no changes in ketone body level as compared to the caprylic acid-treated group. In both fasted and non-fasted mice treated with glucose and caprylic acid, a significant decrease in trunk blood pH occurred as compared to the control group. No alternations in motor coordination or muscular strength were noted with any drug treatment, apart from the caprylic acid and glibenclamide combination, where a significant decrease in the muscle strength was observed. The present study provides a new insight into the role of the adenosine system and low glucose usage in the mechanisms underlying the anticonvulsant effects of caprylic acid in the 6 Hz seizure test., (Copyright © 2014 Elsevier Inc. All rights reserved.)

Ganoderma lucidum is a well-known medicinal mushroom with a long history of use. This study was designed to assess the anticonvulsant potential of an aqueous extract from cultured G. lucidum mycelium in 3 acute seizure models: timed intravenous pentylenetetrazole infusion, maximal electroshock seizure threshold, and 6-Hz-induced psychomotor seizure tests in mice. Moreover, antidepressant-like and anxiolytic-like effects of G. lucidum were evaluated using the forced swim test and the elevated plus maze test in mice, respectively. No changes in seizure thresholds in the intravenous pentylenetetrazole and maximal electroshock seizure threshold tests after acute treatment with G. lucidum extract (200-600 mg/kg) was observed. However, the studied extract (100-400 mg/kg) significantly increased the threshold for psychomotor seizures in the 6-Hz seizure test. In the forced swim test, G. lucidum (100-400 mg/kg) significantly reduced the duration of immobility. No anxiolytic-like or sedative effects were reported in mice pretreated with the extract (400-600 mg/kg). G. lucidum extract (50-2400 mg/kg) did not produce toxic effects in the chimney test (motor coordination) or grip-strength test (neuromuscular strength). Further studies are required to explain the neuropharmacological effects of G. lucidum and to identify its active ingredients that may affect seizure threshold, mood, or anxiety.

Quercetin is one of the most widely occurring flavonoid which is also often present in plants as glycosidic form - rutin. These compounds are ingredients of plant diet and are also present in numerous pharmaceutical preparations and diet supplements which are taken by patients suffering from epilepsy and treating with antiepileptic drugs (AEDs). Influence of these compounds on central nervous system-related effects was proved both in experimental and clinical studies. Their influence on anxiety, depression, memory processes and convulsant activity was reported. The aim of the present study was to investigate the effect of quercetin and rutin in some models of seizures, i.e., in the model of psychomotor seizures induced by 6Hz stimulation, in the maximal electroshock seizure threshold and intravenous pentylenetetrazole tests in mice. We also examined a possible mechanism of anticonvulsant activity of quercetin and its influence on action of two AEDs, i.e., valproic acid and levetiracetam, in the 6Hz seizure test. Our results revealed only a weak anticonvulsant potential of the studied flavonoids because they showed anticonvulsant action at doses from 10 to 200mg/kg only in the 6Hz test and did not change seizure thresholds in the remaining tests. Moreover, anticonvulsant action of the studied flavonoids was short-term, noted only at pretreatment time ranging between 30 and 60min. The highest anticonvulsant activity of quercetin was correlated with its high plasma and brain concentration, which was revealed in a pharmacokinetic study. We did not note changes in the anticonvulsant action of the used AEDs combined with quercetin in the model of psychomotor seizures in mice. Neither quercetin and rutin nor combinations of quercetin with the studied AEDs produced any significant impairments of motor coordination (assessed in the chimney test), muscular strength (investigated in the grip-strength test) and long-term memory (evaluated in the passive avoidance test) in mice. The results of the present study suggest that quercetin and rutin have only weak and short-term anticonvulsant potential. These flavonoids seem to be safe for patients with epilepsy because they neither changed activity of the studied AEDs nor produced any adverse effects., (Copyright © 2014 Elsevier Inc. All rights reserved.)

Background: Identification of new molecular targets as well as the new models recapitulating different aspects of pathophysiology of status epilepticus (SE) in humans might prove essential for the breakthrough in the efforts against pharmacoresistance in epilepsy. Recently, we described a new model of generalized convulsive SE induced with orphenadrine (ORPH) in rats with unique characteristics [5]. The current study was aimed at assessing the efficacy of a new generation antiepileptic drugs (AEDs) and some of the experimental agents in suppressing ORPH-evoked seizures in rats., Methods: ORPH was administered intraperitoneally (ip) in the dose of 80 mg/kg in male Wistar rats. The latency to first seizure, the number of seizure episodes and the duration of overt SE, as well as the incidence of deaths was scored with simultaneous electroencephalographic (EEG) recordings., Results: ORPH induced seizures in 100% of animals at a dose of 80 mg/kg, associated with low mortality and good behavioural outcome. Among new generation AEDs: felbamate, levetiracetam, topiramate, lamotrigine and progabide did not affect the seizure incidence. Among the experimental drugs, only dizocilpine, the non-competitive NMDA antagonist, dose-dependently affected the occurrence of the SE (p<0.001). However, CGP-39551 competitive NMDA antagonist, the same as scopolamine and mecamylamine (muscarinic and nicotinic receptors antagonists, respectively) showed no effect., Conclusions: Based on the above findings, one may speculate that NMDA activation is partly involved in the proconvulsant activity of orphenadrine but may not be the primary pathomechanism. ORPH-induced seizures may provide an interesting option for studying novel targets for pharmacological interventions in status epilepticus., (Copyright © 2014 Institute of Pharmacology, Polish Academy of Sciences. Published by Elsevier Urban & Partner Sp. z o.o. All rights reserved.)

Sildenafil, a selective phosphodiesterase 5 inhibitor (PDE5), has been recently reported to have both pro- and anticonvulsant action in various experimental models of seizures and epilepsy. Furthermore, it affects anticonvulsant action of some antiepileptic drugs (AEDs) in mice seizure tests and both pharmacodynamic and pharmacokinetic interactions were noted. The present study was carried out to investigate influence of sildenafil on the threshold for 6 Hz-induced psychomotor seizures in mice. Effect of sildenafil on activity of some AEDs, i.e., phenobarbital (PB), clonazepam (CZP), ethosuximide (ETS), valproic acid (VPA), tiagabine (TGB), oxcarbazepine (OXC) and levetiracetam (LEV), in 6 Hz test was also examined. Moreover, combination of sildenafil with LEV was investigated in terms of influence on motor coordination (determined by the chimney test), muscular strength (evaluated in the grip-strength test) and long-term memory (assessed in the passive avoidance task) in mice. To determine the type of pharmacological interaction between sildenafil and LEV, free plasma and total brain concentrations of this AED were determined by LC-MS/MS method. Sildenafil at a dose ranging from 10 to 40 mg/kg statistically increased psychomotor seizure threshold in mice. Moreover, sildenafil enhanced the anticonvulsant action of all the studied AEDs in this test. Interactions between this PDE5 inhibitor and PB, CZP, ETS, TGB and OXC seem to be pharmacodynamic. Since sildenafil increased free plasma and total brain concentration of LEV, interactions between these drugs have pharmacokinetic nature. This kind of interaction was also noted between sildenafil and VPA. Neither LEV (2.32 mg/kg) nor its co-administration with sildenafil (40 mg/kg) produced any significant changes in motor coordination, muscular strength and long-term memory in mice., (© 2013.)

The activation of the mu-opioid receptors (MOR) in the central nervous system has a proconvulsant effect and seizures are a common side effect of high doses of short acting opioids, like morphine or fentanyl. However, the correct assessment of the role of MOR blockade in the initiation and propagation of epilepsy was hampered by the lack of potent and selective MOR antagonists. In this study we aimed at characterizing the effect of MOR blockade on the seizure threshold in mice using recently developed selective antagonists antanal-1 and antanal-2 and a classical MOR antagonist, β-funaltrexamine (β-FNA). The effect of the centrally administered MOR antagonists was characterized in the maximal electroshock seizure threshold (MEST), the 6 Hz psychomotor seizure threshold and the intravenous pentylenetetrazole (PTZ) seizure threshold test in mice. The acute effect of the studied compounds on skeletal muscular strength in mice was quantified in the grip-strength test. Antanal-1 and antanal-2 (30 and 50 nmol/mouse, i.c.v.), but not β-FNA significantly increased the seizure threshold in the MEST test in mice. In the 6-Hz test, all tested MOR antagonists significantly increased the psychomotor seizure threshold and the most potent anticonvulsant effect was observed for antanal-2 (2, 10 and 30 nmol/mouse, i.c.v.). The i.c.v. administration of β-FNA (10 and 30 nmol/mouse, i.c.v.), antanal-1 and antanal-2 (both 30, 50 and 100 nmol/mouse, i.c.v.) did not produce any significant effect on PTZ seizure threshold, the generalized clonus or the forelimbs tonus. All tested compounds did not affect muscle strength, as determined in the grip strength test. Our study demonstrated that the novel MOR-selective antagonists antanal-1 and antanal-2 displayed a potent and dose-dependent anticonvulsant action involving non-GABA-ergic, but some other pathways and mechanisms in animal models of epileptic seizures. We suggest that antanals are promising drug templates for future therapeutics, which may be used in the treatment of epilepsy in humans., (Copyright © 2012 Elsevier Inc. All rights reserved.)

Recent studies highlight the involvement of the nitrergic system in the mechanism of action of antidepressant drugs. Sildenafil, a selective PDE5 inhibitor, was shown to abolish the anti-immobility effects of bupropion, venlafaxine and s-citalopram in mice. In this study we assessed the effects of sildenafil on the activity of bupropion and venlafaxine in the forced swim test in mice. Swim trials were conducted by placing mice in glass cylinders filled with water for 6min and the duration of the behavioral immobility during the last 4min of the test was evaluated. Locomotor activity was evaluated with photoresistor actimeters. Brain and serum concentrations of the studied antidepressants were determined by HPLC method. Sildenafil at a dose of 20mg/kg, but not 5 and 10mg/kg, significantly increased the anti-immobility action of bupropion (20mg/kg). The antidepressant activity of venlafaxine (2mg/kg) was potentiated by joint administration with sildenafil at doses of 10 and 20mg/kg. Since the combined treatments did not increase the locomotor activity, the antidepressant-like effects were not related to non-specific behavioral activation. Data from pharmacokinetic studies revealed that sildenafil increased bupropion and venlafaxine levels in serum without affecting their concentrations in the brain. The present study demonstrates the enhancement of anti-immobility action of bupropion and venlafaxine by sildenafil co-administration. The observed changes might have been partly due to pharmacokinetic interactions. However, mechanisms underlying the effects of sildenafil on the antidepressant activity of bupropion and venlafaxine should be carefully evaluated in further studies., (Copyright © 2012 Elsevier Inc. All rights reserved.)

Sildenafil, a selective phosphodiesterase 5 (PDE5) inhibitor, has recently been reported to affect convulsant activity in some animal models of seizures and epilepsy. Moreover, its influence on the protective activity of some antiepileptic drugs (AEDs) was also noted. The aim of the present study was to investigate the effect of sildenafil on the anticonvulsant potential of gabapentin (GBP) and vigabatrin (VGB) in the timed intravenous (i.v.) pentylenetetrazole (PTZ) test in mice. The chimney test, the passive avoidance task and the grip strength test were used to estimate some possible side effects caused by the studied AEDs and their combinations with sildenafil. Total brain and free plasma concentrations of GBP and VGB were determined to evaluate the characteristics of interactions. Our studies revealed that GBP (25-100 mg/kg) increases the threshold for the forelimb tonic extension, whereas VGB raises thresholds both, for myoclonic (200-600 mg/kg) and generalized clonic (400-600 mg/kg) seizures in the used model of seizures. GBP at sub-effective dose of 12.5 mg/kg co-administered with sildenafil at doses of 10 and 20 mg/kg significantly increases the threshold for tonic seizures in the i.v. PTZ test in mice. Combination of sub-effective dose of VGB (200 mg/kg) with sildenafil at a dose of 5mg/kg also showed significant anticonvulsant activity against clonic seizures. The studied AEDs and their combinations with sildenafil did not produce any changes in the motor coordination, long-term memory and muscular strength in mice. Sildenafil did not influence total brain and free plasma concentrations of GBP and VGB. Interactions between the studied AEDs and sildenafil were pharmacodynamic in nature and for that reason they are worthy of consideration in the clinical practice., (Copyright © 2012 Elsevier Inc. All rights reserved.)