Dorota Zolkowska - Academia.edu (original) (raw)

Papers by Dorota Zolkowska

Annals of the New York Academy of Sciences, 2016

Exposures to seizure-inducing chemical threat agents are a major public health concern. Of partic... more Exposures to seizure-inducing chemical threat agents are a major public health concern. Of particular need is improved treatment to terminate convulsions and to prevent the long-term neurological sequelae in survivors. We are studying the organophosphorus cholinesterase inhibitor diisopropyl fluorophosphate (DFP) and the GABA receptor inhibitor tetramethylenedisulfotetramine (TETS), which arguably encompass the mechanistic spectrum of seizure-inducing chemical threats, with the goal of identifying therapeutic approaches with broad-spectrum efficacy. Research efforts have focused on developing translational models and translational diagnostic approaches, including (1) in vivo models of DFP- and TETS-induced seizures for studying neuropathological mechanisms and identifying treatment approaches; (2) in vivo imaging modalities for noninvasive longitudinal monitoring of neurological damage and response to therapeutic candidates; and (3) higher-throughput in vitro platforms for rapid scr...

Annales Universitatis Mariae Curie-Skłodowska. Sectio D: Medicina, 2002

Local anesthetics are widely used in alleviating pain concomitant with small surgery procedures a... more Local anesthetics are widely used in alleviating pain concomitant with small surgery procedures and in dentistry. Especially medication in ductal anesthesia after penetrating into systemic circulation can have significant influence on the central nervous system and stimulus conduction in the heart. Clonidine and reserpine are centrally acting antihypertensive drugs. The aim of this study was to examine an interaction of lidocaine, articaine and mepivacaine with some antihypertensive drugs clonidine and reserpine on the pentylenetetrazole induced seizures. articaine is the most safe local anesthetic and can be used in epileptic patients Co-administration of local anesthetics with centrally acting antihypertensive drugs did not influence seizures activity in mice.

Pharmacological Reports, 2015

Psychopharmacology, Jan 3, 2015

Abnormalities in excitatory/inhibitory neurotransmission are hypothesized to contribute to autism... more Abnormalities in excitatory/inhibitory neurotransmission are hypothesized to contribute to autism spectrum disorder (ASD) etiology. BTBR T (+) Itpr3 (tf) /J (BTBR), an inbred mouse strain, displays social deficits and repetitive self-grooming, offering face validity to ASD diagnostic symptoms. Reduced GABAergic neurotransmission in BTBR suggests that GABAA receptor positive allosteric modulators (PAMs) could improve ASD-relevant BTBR phenotypes. The neuroactive steroid ganaxolone acts as a PAM, displaying anticonvulsant properties in rodent epilepsy models and an anxiolytic-like profile in the elevated plus-maze. We evaluated ganaxolone in BTBR and C57BL/6J mice in standardized assays for sociability and repetitive behaviors. Open field and anxiety-related behaviors were tested as internal controls and for comparison with the existing neuroactive steroid literature. Ganaxolone improved aspects of social approach and reciprocal social interactions in BTBR, with no effect on repetitiv...

Progress in Neuro-Psychopharmacology and Biological Psychiatry, 2016

The aim of this study was to determine the effects of 2-methyl-6-(phenylethynyl)pyridine (MPEP - ... more The aim of this study was to determine the effects of 2-methyl-6-(phenylethynyl)pyridine (MPEP - a selective antagonist for the glutamate metabotropic receptor subtype mGluR5) on the protective action of some novel antiepileptic drugs (lamotrigine, oxcarbazepine, pregabalin and topiramate) against maximal electroshock-induced seizures in mice. Brain concentrations of antiepileptic drugs were measured to determine whether MPEP altered pharmacokinetics of antiepileptic drugs. Intraperitoneal injection of 1.5 and 2mg/kg of MPEP significantly elevated the threshold for electroconvulsions in mice, whereas MPEP at a dose of 1mg/kg considerably enhanced the anticonvulsant activity of pregabalin and topiramate, but not that of lamotrigine or oxcarbazepine in the maximal electroshock-induced seizures in mice. Pharmacokinetic results revealed that MPEP (1mg/kg) did not alter total brain concentrations of pregabalin and topiramate, and the observed effect in the mouse maximal electroshock seizure model was pharmacodynamic in nature. Collectively, our preclinical data suggest that MPEP may be a safe and beneficial adjunct to the therapeutic effects of antiepileptic drugs in human patients.

The Journal of physiology, Jan 17, 2015

Most barbiturates are anaesthetics but a few unexpectedly are convulsants. We recently located th... more Most barbiturates are anaesthetics but a few unexpectedly are convulsants. We recently located the anaesthetic sites on GABAA Rs by photolabeling with an anaesthetic barbiturate. To apply the same strategy to locate the convulsant sites requires the creation and mechanistic characterization of a suitable agent. We synthesized enantiomers of a novel, photoactivable barbiturate, mTFD-MPPB (1-methyl-5-propyly-5-(m-trifluoromethyldiazirinyl) phenyl barbituric acid). In mice, S-mTFD-MPPB acted as a convulsant, whereas R-mTFD-MPPB acted as an anticonvulsant. Using patch clamp electrophysiology and fast solution exchange on recombinant human α1β3γ2L GABAA Rs expressed in HEK cells, we found that S-mTFD-MPPB inhibited GABA-induced currents, whereas R-mTFD-MPPB enhanced them. S-mTFD-MPPB caused inhibition by binding to either of two inhibitory sites on open channels with bimolecular kinetics. It also inhibited closed, resting state receptors at similar concentrations, decreasing the channel ...

Toxicology and Applied Pharmacology, 2014

Tetramethylenedisulfotetramine (TETS) is a potent convulsant poison for which there is currently ... more Tetramethylenedisulfotetramine (TETS) is a potent convulsant poison for which there is currently no approved antidote. The convulsant action of TETS is thought to be mediated by inhibition of type A gamma-aminobutyric acid receptor (GABAAR) function. We, therefore, investigated the effects of post-exposure administration of diazepam, a GABAAR positive allosteric modulator, on seizure activity, death and neuroinflammation in adult male Swiss mice injected with a lethal dose of TETS (0.15mg/kg, ip). Administration of a high dose of diazepam (5mg/kg, ip) immediately following the second clonic seizure (approximately 20min post-TETS injection) effectively prevented progression to tonic seizures and death. However, this treatment did not prevent persistent reactive astrogliosis and microglial activation, as determined by GFAP and Iba-1 immunoreactivity and microglial cell morphology. Inhibition of soluble epoxide hydrolase (sEH) has been shown to exert potent anti-inflammatory effects and to increase survival in mice intoxicated with other GABAAR antagonists. The sEH inhibitor TUPS (1mg/kg, ip) administered immediately after the second clonic seizure did not protect TETS-intoxicated animals from tonic seizures or death. Combined administration of diazepam (5mg/kg, ip) and TUPS (1mg/kg, ip, starting 1h after diazepam and repeated every 24h) prevented TETS-induced lethality and influenced signs of neuroinflammation in some brain regions. Significantly decreased microglial activation and enhanced reactive astrogliosis were observed in the hippocampus, with no changes in the cortex. Combining an agent that targets specific anti-inflammatory mechanisms with a traditional antiseizure drug may enhance treatment outcome in TETS intoxication.

Neurotherapeutics : the journal of the American Society for Experimental NeuroTherapeutics, Jan 26, 2014

Inhibitors of voltage-gated sodium channels (Nav) have been used as anticonvulsants since the 194... more Inhibitors of voltage-gated sodium channels (Nav) have been used as anticonvulsants since the 1940s, while potassium channel activators have only been investigated more recently. We here describe the discovery of 2-amino-6-trifluoromethylthio-benzothiazole (SKA-19), a thioanalog of riluzole, as a potent, novel anticonvulsant, which combines the two mechanisms. SKA-19 is a use-dependent NaV channel blocker and an activator of small-conductance Ca(2+)-activated K(+) channels. SKA-19 reduces action potential firing and increases medium afterhyperpolarization in CA1 pyramidal neurons in hippocampal slices. SKA-19 is orally bioavailable and shows activity in a broad range of rodent seizure models. SKA-19 protects against maximal electroshock-induced seizures in both rats (ED50 1.6 mg/kg i.p.; 2.3 mg/kg p.o.) and mice (ED50 4.3 mg/kg p.o.), and is also effective in the 6-Hz model in mice (ED50 12.2 mg/kg), Frings audiogenic seizure-susceptible mice (ED50 2.2 mg/kg), and the hippocampal ki...

Psychopharmacology, 2014

Rationale Androsterone [(3α,5α)-3-hydroxyandrostan-17one; 5α,3α-A] and its 5β-epimer etiocholanol... more Rationale Androsterone [(3α,5α)-3-hydroxyandrostan-17one; 5α,3α-A] and its 5β-epimer etiocholanolone [(3α,5β)-3-hydroxyandrostan-17-one; 5β,3α-A)], the major excreted metabolites of testosterone, are neurosteroid positive modulators of GABA A receptors. Such neurosteroids typically show enantioselectivity in which the natural form is more potent than the corresponding unnatural enantiomer. For 5α,3α-A and 5β,3α-A, the unnatural enantiomers are more potent at GABA A receptors than the natural forms.

Pharmacological Reports, 2013

The aim of this study was to determine the effects of N-(morpholinomethyl)-p-isopropoxy-phenylsuc... more The aim of this study was to determine the effects of N-(morpholinomethyl)-p-isopropoxy-phenylsuccinimide (MMIPPS) on the protective action of four classical antiepileptic drugs (AEDs: carbamazepine [CBZ], phenobarbital [PB], phenytoin [PHT] and valproate [VPA]) against maximal electroshock (MES)-induced seizures in mice. Tonic hind limb extension (seizure activity) was evoked in adult male albino Swiss mice by a current (sine-wave, 25 mA, 500 V, 50 Hz, 0.2 s stimulus duration) delivered via auricular electrodes. Total brain concentrations of AEDs were measured to determine the characteristics of interaction between MMIPPS and classical AEDs in the mouse MES model. MMIPPS administered intraperitoneally (ip) at 100 mg/kg significantly elevated the threshold for electroconvulsions in mice (p < 0.01). MMIPPS at doses of 25 and 50 mg/kg had no impact on the threshold for electroconvulsions in mice. Moreover, MMIPPS (50 mg/kg) significantly enhanced the anticonvulsant activity of PB and VPA (p < 0.05), but not that of CBZ or PHT, in the MES test in mice. Pharmacokinetic studies revealed that MMIPPS (50 mg/kg) did not alter total brain concentrations of PB, but significantly elevated total brain concentrations of VPA in mice (p < 0.05). The enhanced anticonvulsant action of PB by MMIPPS in the mouse MES model and lack of any pharmacokinetic interaction between drugs make the combination of MMIPPS with PB of pivotal importance for further experimental and clinical studies. Pharmacokinetic increase in total brain VPA concentration seems to be responsible for the enhanced anticonvulsant action of VPA by MMIPPS in the mouse MES model. The combinations of MMIPPS with CBZ and PHT are neutral from a preclinical viewpoint.

Pharmacological Reports, 2011

The objective of this study was to determine the effects of 7-nitroindazole (7NI--a preferential ... more The objective of this study was to determine the effects of 7-nitroindazole (7NI--a preferential neuronal nitric oxide synthase (NOS) inhibitor) and NG-nitro-L-arginine (NNA--a non-selective NOS inhibitor) on the anticonvulsant action of pregabalin (PGB--a third-generation antiepileptic drug) in the maximal electroshock (MES)-induced seizure model in mice. Electroconvulsions were produced in mice by means of an alternating current (50 Hz, 500 V, 25 mA, ear-clip electrodes, 0.2 s stimulus duration, tonic hindlimb extension taken as the endpoint). The anticonvulsant action of PGB in the MES test was expressed as median effective doses (ED50 values) of the drug, protecting 50% of animals tested against MES-induced seizures. The acute adverse-effect potentials of PGB in combination with 7NI and NNA were evaluated in the chimney test (motor coordination), step-through passive avoidance task (long-term memory) and grip-strength test (skeletal muscular strength) in mice. 7NI (50 mg/kg, ip) significantly enhanced the anticonvulsant action of PGB by reducing the ED50 value of PGB from 145.0 mg/kg to 74.4 mg/kg (p<0.01). Similarly, 7NI at the lower dose of 25 mg/kg also potentiated the anticonvulsant action of PGB by lowering the ED50 value of PGB from 145.0 mg/kg to 117.9 mg/kg, although the results did not attain statistical significance. In contrast, NNA (40 mg/kg, ip) had no impact on the anticonvulsant effects of PGB. Moreover, none of the examined combinations of PGB with 7NI and NNA affected motor coordination, long-term memory and skeletal muscular strength in mice. Based on this preclinical study, one can conclude that 7NI significantly enhanced and NNA had no effect on the anticonvulsant activity of PGB against MES-induced seizures in mice.

Neuroscience, 2013

Botulinum neurotoxins (BoNTs) may affect the excitability of brain circuits by inhibiting neurotr... more Botulinum neurotoxins (BoNTs) may affect the excitability of brain circuits by inhibiting neurotransmitter release at central synapses. There is evidence that local delivery of BoNT serotypes A and E, which target SNAP-25, a component of the release machinery specific to excitatory synapses, can inhibit seizure generation. BoNT serotype B (BoNT/B) targets VAMP2, which is expressed in both excitatory and inhibitory terminals. Here we assessed the effects of unilateral intrahippocampal infusion of BoNT/B in the rat on intravenous pentylenetetrazol (PTZ) seizure thresholds, and on the expression of spontaneous behavioral and electrographic seizures. Infusion of BoNT/B (500 and 1000 unit) by convection-enhanced delivery caused a reduction in myoclonic twitch and clonic seizure thresholds in response to intravenous PTZ beginning about 6 days after the infusion. Handling-evoked and spontaneous convulsive seizures were observed in many BoNT/B-treated animals but not in vehicle-treated controls. Spontaneous electrographic seizure discharges were recorded in the dentate gyrus of animals that received local BoNT/B infusion. In addition, there was an increased frequency of interictal epileptiform spikes and sharp waves at the same recording site. BoNT/B-treated animals also exhibited tactile hyperresponsivity in comparison with vehicle-treated controls. This is the first demonstration that BoNT/B causes a delayed proconvulsant action when infused into the hippocampus. Local infusion of BoNT/B could be useful as a focal epilepsy model. Ó

Journal of Pharmacology and Experimental Therapeutics, 2006

Elevations in plasma serotonin (5-HT) have been implicated in the pathogenesis of cardiac and pul... more Elevations in plasma serotonin (5-HT) have been implicated in the pathogenesis of cardiac and pulmonary disease. Normally, plasma 5-HT concentrations are kept low by transporter-mediated uptake of 5-HT into platelets and by metabolism to 5-hydroxyindoleacetic acid (5-HIAA). Many abused drugs (e.g., substituted amphetamines) and prescribed medications (e.g., fluoxetine) target 5-HT transporters and could thereby influence circulating 5-HT. We evaluated the effects of amphetamines analogs [(+/-)-fenfluramine, (+/-)-3,4-methylenedioxymethamphetamine, (+)-methamphetamine, (+)-amphetamine, phentermine] on extracellular levels (i.e., plasma levels) of 5-HT and 5-HIAA in blood from catheterized rats. Effects of the 5-HT uptake blocker fluoxetine were examined for comparison. Drugs were tested in vivo and in vitro; plasma indoles were measured using a novel microdialysis method in whole blood. We found that baseline dialysate levels of 5-HT are approximately 0.22 nM, and amphetamine analogs evoke large dose-dependent increases in plasma 5-HT ranging from 4 to 20 nM. The ability of drugs to elevate plasma 5-HT is positively correlated with their potency as 5-HT transporter substrates. Fluoxetine produced small, but significant, increases in plasma 5-HT. Although the drug-evoked 5-HT concentrations are below the micromolar levels required for contraction of pulmonary arteries, they approach concentrations reported to stimulate mitogenesis in pulmonary artery smooth muscle cells. Additional studies are needed to determine the effects of chronic administration of amphetamines on circulating 5-HT.

Journal of Pharmacology and Experimental Therapeutics, 2007

Large elevations in blood serotonin (5-hydroxytryptamine; 5-HT) can produce valvular heart diseas... more Large elevations in blood serotonin (5-hydroxytryptamine; 5-HT) can produce valvular heart disease in humans and laboratory animals. In accordance, one prevailing hypothesis (i.e., the "5-HT hypothesis") suggests that 5-HT transporter substrates like fenfluramine increase the risk for valvular heart disease by elevating plasma 5-HT, secondary to the release of 5-HT from platelets. The main purpose of this study was to determine whether chronic administration of fenfluramine increases plasma 5-HT to concentrations that are associated with the development of valvular heart disease. To the best of our knowledge, this is the first study to address this issue using an in vivo microdialysis method that measures plasma 5-HT in nonhypoxic rats. We examined the effects of chronic (Ϯ)-fenfluramine and fluoxetine on plasma levels of 5-HT and its metabolite, 5-hydroxyindoleacetic acid (5-HIAA), in blood samples from conscious catheterized rats. Plasma indoles were measured by high-performance liquid chromatography with electrochemical detection in the dialysates of whole blood. The baseline plasma 5-HT level was Ͻ1.0 nM. Chronic fenfluramine (14-day minipump infusion) produced small increases in baseline plasma 5-HT (ϳ2-4-fold), whereas chronic fluoxetine had no effect. Chronic fenfluramine and fluoxetine markedly decreased whole-blood 5-HT and reduced the ability of acute fenfluramine to evoke 5-HT release. Elevations in baseline plasma 5-HT produced by chronic fenfluramine are far below the micromolar levels necessary to produce valvular heart disease. Furthermore, chronic fenfluramine reduces the ability of acute fenfluramine to increase plasma 5-HT, suggesting that the 5-HT hypothesis cannot explain the increased risk of valvular heart disease in patients treated with fenfluramine.

Journal of Pharmacology and Experimental Therapeutics, 2011

The lung provides a portal of entry for drug delivery that could be used to administer anticonvul... more The lung provides a portal of entry for drug delivery that could be used to administer anticonvulsant substances to prevent or abort seizures. Here, we demonstrate that intrapulmonary propofol hemisuccinate (PHS) rapidly confers seizure protection in various rodent chemoconvulsant models. Propofol is a powerful anticonvulsant substance at subanesthetic doses, but it is a viscous, water-immiscible oil that is not suitable for intrapulmonary administration. We found that PHS can be formulated as an aqueous solution that is well tolerated when instilled into the lung. High-dose intraperitoneally administered PHS induced loss-of-righting reflex in rats and mice. The onset of action of PHS was delayed in comparison with propofol, suggesting that conversion to propofol is required for activity. A lower dose of PHS (40 mg/kg i.p.) did not cause general anesthesia but protected against pentylenetetrazol (PTZ)-induced seizures in rats. Intrapulmonary administration of an aqueous PHS solution via a tracheal cannula at lower doses (5 and 10 mg/kg) conferred equivalent seizure protection without acute motor toxicity. In mice, intraperitoneal PHS (60-80 mg/kg) was associated with an elevation in PTZ, bicuculline, picrotoxin, and kainic acid seizure thresholds. Intratracheal PHS was markedly more potent, producing seizure threshold elevations at doses of 10 to 15 mg/kg. In the PTZ threshold model in mice, PHS was active at 5 min, maximally active at 10 min, and no longer active at 20 min. Intratracheal PHS also prolonged the onset of 4-aminopyridine-induced convulsions but did not affect the threshold for N-methyl-D-aspartate-induced convulsions. We conclude that intratracheal administration of an aqueous solution of PHS, a putative propofol prodrug, provides potent seizure protection of rapid onset and brief duration. Intrapulmonary PHS may be useful for preventing the spread of seizures or aborting seizure clusters without causing prolonged sedation.

Journal of Pharmacology and Experimental Therapeutics, 2009

Modafinil is prescribed for numerous medical conditions, but the drug's mechanism of action is un... more Modafinil is prescribed for numerous medical conditions, but the drug's mechanism of action is unclear. Here, we examined the interaction of modafinil with receptors and transporters in vitro and compared pharmacological effects of the drug with those produced by indirect dopamine (DA) agonists 1-[2-[bis(4fluorophenyl)methoxy]ethyl]-4-(3-phenylpropyl)piperazine (GBR12909) and (ϩ)-methamphetamine (METH). Modafinil was screened at various receptors and transporters using binding assays. Transporter-mediated uptake and release were examined in rat brain synaptosomes. Effects of modafinil on motor activity and neurochemistry were determined in rats undergoing in vivo microdialysis in nucleus accumbens. Of the receptors and transporters assayed, modafinil displayed measurable potency only at DA transporters (DAT), inhibiting [ 3 H]DA uptake, with an IC 50 value of 4.0 M. Accordingly, modafinil pretreatment (10 M) antagonized METH-induced release of the DAT substrate [ 3 H]1-methyl-4-phenylpyridinium. Intravenous modafinil (20 and 60 mg/kg) produced dose-dependent increases in motor activity and extracellular DA, without affecting serotonin (5-HT). Analogous results were observed for GBR12909 (1 and 3 mg/kg), whereas METH (0.3 and 1 mg/ kg) increased DA and 5-HT. Locomotor effects of all drugs were positively correlated with dialysate DA (P Ͻ 0.001). Interestingly, modafinil pretreatment reduced METH-induced ambulation and DA release. Our data show that modafinil interacts with DAT sites in rat brain, a property shared with agonist medications under investigation for treating cocaine dependence. Nondopaminergic mechanisms may also contribute to the pharmacology of modafinil. Finally, the results suggest that modafinil should be tested as an adjunct for treating METH addiction.

European Journal of Pharmacology, 2010

The aim of the study was to determine the influence of N-(ortho-carboxyanilinomethyl)-p-isopropox... more The aim of the study was to determine the influence of N-(ortho-carboxyanilinomethyl)-p-isopropoxyphenylsuccinimide [o-CAMIPPS], N-(meta-carboxyanilinomethyl)-p-isopropoxyphenylsuccinimide [m-CAMIPPS], and N-(para-carboxyanilinomethyl)-p-isopropoxyphenylsuccinimide [p-CAMIPPS] on the protective activity of four classical antiepileptic drugs (carbamazepine, phenobarbital, phenytoin and valproate) in the mouse maximal electroshock seizure model. The results indicate that all tested succinimide derivatives administered intraperitoneally at doses of 75 and 150 mg/kg significantly elevated the threshold for electroconvulsions in mice. Succinimide derivatives at a dose of 37.5 mg/kg had no effect on the threshold for electroconvulsions in mice. Furthermore, o-CAMIPPS (37.5 mg/kg) significantly reduced the anticonvulsant activity of carbamazepine, but not that of phenobarbital, phenytoin and valproate in the maximal electroshock-induced seizures in mice. Anticonvulsant efficacy of carbamazepine, phenobarbital, phenytoin and valproate in the maximal electroshock-induced seizures in mice was not changed after administration of m-CAMIPPS or p-CAMIPPS. Pharmacokinetic experiment revealed that o-CAMIPPS significantly increased total brain concentrations of carbamazepine in mice. In conclusion, the reduced anticonvulsant action of carbamazepine by o-CAMIPPS in the maximal electroshock-induced seizures, despite the increased total brain carbamazepine concentrations after combined administration of carbamazepine with o-CAMIPPS, may suggest the antagonistic interaction between drugs. The combinations of m-CAMIPPS or p-CAMIPPS with carbamazepine, phenobarbital, phenytoin and valproate were neutral from a preclinical viewpoint.

Epilepsy Research, 2012

Experimental epileptology is mainly focused on searching for some active compounds suppressing se... more Experimental epileptology is mainly focused on searching for some active compounds suppressing seizures that could become efficacious antiepileptic drugs. Accumulating evidence indicates that succinimide derivatives would be good candidates for novel antiepileptic drugs. Therefore, the aim of this study was to determine the effects of N-hydroxymethyl-p-isopropoxyphenyl-succinimide (HMIPPS) on the protective action of four classical antiepileptic drugs (carbamazepine, phenobarbital, phenytoin and valproate) in the maximal electroshock-induced seizure test in mice. Tonic hind limb extension (seizure activity) was evoked in adult male albino Swiss mice by a current (sine-wave, 25 mA, 500 V, 50 Hz, 0.2s stimulus duration) delivered via auricular electrodes. Acute adverse-effect profiles with respect to motor performance, long-term memory and skeletal muscular strength were measured along with total brain antiepileptic drug concentrations. Results indicate that HMIPPS administered intraperitoneally at 100mg/kg significantly elevated the threshold for electroconvulsions in mice (P<0.05). HMIPPS at doses of 12.5, 25 and 50mg/kg had no impact on the threshold for electroconvulsions in mice. Moreover, HMIPPS (50mg/kg) significantly enhanced the anticonvulsant activity of phenobarbital and valproate in the mouse maximal electroshock-induced seizure model by reducing their median effective doses (ED(50) values) from 23.25mg/kg to 16.82 mg/kg (P<0.01; for phenobarbital) and from 259.3mg/kg to 189.7 mg/kg (P<0.001; for valproate), respectively. In contrast, HMIPPS (50mg/kg) had no impact on the protective action of carbamazepine or phenytoin in the maximal electroshock seizure test in mice. HMIPPS (25mg/kg) significantly potentiated the anticonvulsant action of valproate by reducing its ED(50) value from 259.3mg/kg to 210.6 mg/kg (P>0.05), but not that of phenobarbital, phenytoin and carbamazepine in the mouse maximal electroshock-induced seizure model. Pharmacokinetic experiments revealed that HMIPPS did not alter total brain concentrations of phenobarbital or valproate in mice. Moreover, none of the examined combinations of HMIPPS (50mg/kg) with carbamazepine, phenobarbital, phenytoin and valproate (at their ED(50) values from the maximal electroshock-induced seizure test) affected motor coordination in the chimney test, long-term memory in the passive avoidance task, and muscular strength in the grip-strength test in mice, indicating no possible acute adverse effects in animals. In conclusion, the enhanced anticonvulsant action of phenobarbital and valproate by HMIPPS in the mouse maximal electroshock-induced seizure model, lack of pharmacokinetic interactions and no potential acute adverse effects make the combinations of HMIPPS with phenobarbital and valproate worthy of consideration for further experimental and clinical studies. The combinations of HMIPPS with carbamazepine and phenytoin are neutral from a preclinical viewpoint.

Epilepsia, 2013

Benzodiazepines are the current first-line standard-of-care treatment for status epilepticus but ... more Benzodiazepines are the current first-line standard-of-care treatment for status epilepticus but fail to terminate seizures in about one third of cases. Synaptic GABA A receptors, which mediate phasic inhibition in central circuits, are the molecular target of benzodiazepines. As status epilepticus progresses, these receptors are internalized and become functionally inactivated, conferring benzodiazepine resistance, which is believed to be a major cause of treatment failure. GABA A receptor positive allosteric modulator neuroactive steroids, such as allopregnanolone, also potentiate synaptic GABA A receptors, but in addition they enhance extrasynaptic GABA A receptors that mediate tonic inhi-bition. Extrasynaptic GABA A receptors are not internalized, and desensitization of these receptors does not occur during continuous seizures in status epilepticus models. Here we review the broad-spectrum antiseizure activity of allopregnanolone in animal seizure models and the evidence for its activity in models of status epilepticus. We also demonstrate that allopregnanolone inhibits ongoing behavioral and electrographic seizures in a model of status epilepticus, even when there is benzodiazepine resistance. Parenteral allopregnanolone may provide an improved treatment for refractory status epilepticus.

Annals of the New York Academy of Sciences, 2008

Dual dopamine (DA)/serotonin (5-HT)-releasing agents are promising candidate medications for stim... more Dual dopamine (DA)/serotonin (5-HT)-releasing agents are promising candidate medications for stimulant addiction and other disorders. However, certain 5-HT transporter (SERT) substrates are associated with development of idiopathic pulmonary arterial hypertension (IPAH) and valvular heart disease (VHD). According to the "5-HT hypothesis," SERT substrates increase the risk for developing IPAH and VHD by increasing plasma 5-HT. To test this hypothesis directly, we determined the effects of acute and chronic fenfluramine, and other SERT ligands, on plasma 5-HT in male rats. For acute treatments, rats received i.v. vehicle or test drug (0.3 and 1.0 mg/kg), and serial blood samples were withdrawn. For chronic treatments, vehicle or test drug was infused via osmotic minipump (3 and 10 mg/kg/d) for 2 weeks. On the last day of infusion, rats received i.v. fenfluramine challenge (1 mg/kg), and serial blood samples were withdrawn. Plasma 5-HT was measured using ex vivo microdialysis in whole-blood samples. Baseline plasma 5-HT was <1.0 nM. Acute injection of fenfluramine or other SERT substrates caused large (up to 24-fold) dose-dependent increases in plasma 5-HT. Chronic fenfluramine at 3 and 10 mg/kg/d produced 1.7- and 3.5-fold increases in baseline plasma 5-HT, while chronic fluoxetine had no effect. Chronic infusions of fenfluramine or fluoxetine diminished the ability of acute fenfluramine to elevate dialysate 5-HT, and both drugs markedly reduced whole-blood 5-HT. Acute fenfluramine increases plasma 5-HT to concentrations that are below the micromolar levels necessary to produce adverse cardiovascular effects. Chronic fenfluramine and fluoxetine have minimal effects on plasma 5-HT, suggesting that the increased risk for IPAH associated with fenfluramine does not depend upon elevations in plasma 5-HT.

Annals of the New York Academy of Sciences, 2016

Exposures to seizure-inducing chemical threat agents are a major public health concern. Of partic... more Exposures to seizure-inducing chemical threat agents are a major public health concern. Of particular need is improved treatment to terminate convulsions and to prevent the long-term neurological sequelae in survivors. We are studying the organophosphorus cholinesterase inhibitor diisopropyl fluorophosphate (DFP) and the GABA receptor inhibitor tetramethylenedisulfotetramine (TETS), which arguably encompass the mechanistic spectrum of seizure-inducing chemical threats, with the goal of identifying therapeutic approaches with broad-spectrum efficacy. Research efforts have focused on developing translational models and translational diagnostic approaches, including (1) in vivo models of DFP- and TETS-induced seizures for studying neuropathological mechanisms and identifying treatment approaches; (2) in vivo imaging modalities for noninvasive longitudinal monitoring of neurological damage and response to therapeutic candidates; and (3) higher-throughput in vitro platforms for rapid scr...

Annales Universitatis Mariae Curie-Skłodowska. Sectio D: Medicina, 2002

Local anesthetics are widely used in alleviating pain concomitant with small surgery procedures a... more Local anesthetics are widely used in alleviating pain concomitant with small surgery procedures and in dentistry. Especially medication in ductal anesthesia after penetrating into systemic circulation can have significant influence on the central nervous system and stimulus conduction in the heart. Clonidine and reserpine are centrally acting antihypertensive drugs. The aim of this study was to examine an interaction of lidocaine, articaine and mepivacaine with some antihypertensive drugs clonidine and reserpine on the pentylenetetrazole induced seizures. articaine is the most safe local anesthetic and can be used in epileptic patients Co-administration of local anesthetics with centrally acting antihypertensive drugs did not influence seizures activity in mice.

Pharmacological Reports, 2015

Psychopharmacology, Jan 3, 2015

Abnormalities in excitatory/inhibitory neurotransmission are hypothesized to contribute to autism... more Abnormalities in excitatory/inhibitory neurotransmission are hypothesized to contribute to autism spectrum disorder (ASD) etiology. BTBR T (+) Itpr3 (tf) /J (BTBR), an inbred mouse strain, displays social deficits and repetitive self-grooming, offering face validity to ASD diagnostic symptoms. Reduced GABAergic neurotransmission in BTBR suggests that GABAA receptor positive allosteric modulators (PAMs) could improve ASD-relevant BTBR phenotypes. The neuroactive steroid ganaxolone acts as a PAM, displaying anticonvulsant properties in rodent epilepsy models and an anxiolytic-like profile in the elevated plus-maze. We evaluated ganaxolone in BTBR and C57BL/6J mice in standardized assays for sociability and repetitive behaviors. Open field and anxiety-related behaviors were tested as internal controls and for comparison with the existing neuroactive steroid literature. Ganaxolone improved aspects of social approach and reciprocal social interactions in BTBR, with no effect on repetitiv...

Progress in Neuro-Psychopharmacology and Biological Psychiatry, 2016

The aim of this study was to determine the effects of 2-methyl-6-(phenylethynyl)pyridine (MPEP - ... more The aim of this study was to determine the effects of 2-methyl-6-(phenylethynyl)pyridine (MPEP - a selective antagonist for the glutamate metabotropic receptor subtype mGluR5) on the protective action of some novel antiepileptic drugs (lamotrigine, oxcarbazepine, pregabalin and topiramate) against maximal electroshock-induced seizures in mice. Brain concentrations of antiepileptic drugs were measured to determine whether MPEP altered pharmacokinetics of antiepileptic drugs. Intraperitoneal injection of 1.5 and 2mg/kg of MPEP significantly elevated the threshold for electroconvulsions in mice, whereas MPEP at a dose of 1mg/kg considerably enhanced the anticonvulsant activity of pregabalin and topiramate, but not that of lamotrigine or oxcarbazepine in the maximal electroshock-induced seizures in mice. Pharmacokinetic results revealed that MPEP (1mg/kg) did not alter total brain concentrations of pregabalin and topiramate, and the observed effect in the mouse maximal electroshock seizure model was pharmacodynamic in nature. Collectively, our preclinical data suggest that MPEP may be a safe and beneficial adjunct to the therapeutic effects of antiepileptic drugs in human patients.

The Journal of physiology, Jan 17, 2015

Most barbiturates are anaesthetics but a few unexpectedly are convulsants. We recently located th... more Most barbiturates are anaesthetics but a few unexpectedly are convulsants. We recently located the anaesthetic sites on GABAA Rs by photolabeling with an anaesthetic barbiturate. To apply the same strategy to locate the convulsant sites requires the creation and mechanistic characterization of a suitable agent. We synthesized enantiomers of a novel, photoactivable barbiturate, mTFD-MPPB (1-methyl-5-propyly-5-(m-trifluoromethyldiazirinyl) phenyl barbituric acid). In mice, S-mTFD-MPPB acted as a convulsant, whereas R-mTFD-MPPB acted as an anticonvulsant. Using patch clamp electrophysiology and fast solution exchange on recombinant human α1β3γ2L GABAA Rs expressed in HEK cells, we found that S-mTFD-MPPB inhibited GABA-induced currents, whereas R-mTFD-MPPB enhanced them. S-mTFD-MPPB caused inhibition by binding to either of two inhibitory sites on open channels with bimolecular kinetics. It also inhibited closed, resting state receptors at similar concentrations, decreasing the channel ...

Toxicology and Applied Pharmacology, 2014

Tetramethylenedisulfotetramine (TETS) is a potent convulsant poison for which there is currently ... more Tetramethylenedisulfotetramine (TETS) is a potent convulsant poison for which there is currently no approved antidote. The convulsant action of TETS is thought to be mediated by inhibition of type A gamma-aminobutyric acid receptor (GABAAR) function. We, therefore, investigated the effects of post-exposure administration of diazepam, a GABAAR positive allosteric modulator, on seizure activity, death and neuroinflammation in adult male Swiss mice injected with a lethal dose of TETS (0.15mg/kg, ip). Administration of a high dose of diazepam (5mg/kg, ip) immediately following the second clonic seizure (approximately 20min post-TETS injection) effectively prevented progression to tonic seizures and death. However, this treatment did not prevent persistent reactive astrogliosis and microglial activation, as determined by GFAP and Iba-1 immunoreactivity and microglial cell morphology. Inhibition of soluble epoxide hydrolase (sEH) has been shown to exert potent anti-inflammatory effects and to increase survival in mice intoxicated with other GABAAR antagonists. The sEH inhibitor TUPS (1mg/kg, ip) administered immediately after the second clonic seizure did not protect TETS-intoxicated animals from tonic seizures or death. Combined administration of diazepam (5mg/kg, ip) and TUPS (1mg/kg, ip, starting 1h after diazepam and repeated every 24h) prevented TETS-induced lethality and influenced signs of neuroinflammation in some brain regions. Significantly decreased microglial activation and enhanced reactive astrogliosis were observed in the hippocampus, with no changes in the cortex. Combining an agent that targets specific anti-inflammatory mechanisms with a traditional antiseizure drug may enhance treatment outcome in TETS intoxication.

Neurotherapeutics : the journal of the American Society for Experimental NeuroTherapeutics, Jan 26, 2014

Inhibitors of voltage-gated sodium channels (Nav) have been used as anticonvulsants since the 194... more Inhibitors of voltage-gated sodium channels (Nav) have been used as anticonvulsants since the 1940s, while potassium channel activators have only been investigated more recently. We here describe the discovery of 2-amino-6-trifluoromethylthio-benzothiazole (SKA-19), a thioanalog of riluzole, as a potent, novel anticonvulsant, which combines the two mechanisms. SKA-19 is a use-dependent NaV channel blocker and an activator of small-conductance Ca(2+)-activated K(+) channels. SKA-19 reduces action potential firing and increases medium afterhyperpolarization in CA1 pyramidal neurons in hippocampal slices. SKA-19 is orally bioavailable and shows activity in a broad range of rodent seizure models. SKA-19 protects against maximal electroshock-induced seizures in both rats (ED50 1.6 mg/kg i.p.; 2.3 mg/kg p.o.) and mice (ED50 4.3 mg/kg p.o.), and is also effective in the 6-Hz model in mice (ED50 12.2 mg/kg), Frings audiogenic seizure-susceptible mice (ED50 2.2 mg/kg), and the hippocampal ki...

Psychopharmacology, 2014

Rationale Androsterone [(3α,5α)-3-hydroxyandrostan-17one; 5α,3α-A] and its 5β-epimer etiocholanol... more Rationale Androsterone [(3α,5α)-3-hydroxyandrostan-17one; 5α,3α-A] and its 5β-epimer etiocholanolone [(3α,5β)-3-hydroxyandrostan-17-one; 5β,3α-A)], the major excreted metabolites of testosterone, are neurosteroid positive modulators of GABA A receptors. Such neurosteroids typically show enantioselectivity in which the natural form is more potent than the corresponding unnatural enantiomer. For 5α,3α-A and 5β,3α-A, the unnatural enantiomers are more potent at GABA A receptors than the natural forms.

Pharmacological Reports, 2013

The aim of this study was to determine the effects of N-(morpholinomethyl)-p-isopropoxy-phenylsuc... more The aim of this study was to determine the effects of N-(morpholinomethyl)-p-isopropoxy-phenylsuccinimide (MMIPPS) on the protective action of four classical antiepileptic drugs (AEDs: carbamazepine [CBZ], phenobarbital [PB], phenytoin [PHT] and valproate [VPA]) against maximal electroshock (MES)-induced seizures in mice. Tonic hind limb extension (seizure activity) was evoked in adult male albino Swiss mice by a current (sine-wave, 25 mA, 500 V, 50 Hz, 0.2 s stimulus duration) delivered via auricular electrodes. Total brain concentrations of AEDs were measured to determine the characteristics of interaction between MMIPPS and classical AEDs in the mouse MES model. MMIPPS administered intraperitoneally (ip) at 100 mg/kg significantly elevated the threshold for electroconvulsions in mice (p < 0.01). MMIPPS at doses of 25 and 50 mg/kg had no impact on the threshold for electroconvulsions in mice. Moreover, MMIPPS (50 mg/kg) significantly enhanced the anticonvulsant activity of PB and VPA (p < 0.05), but not that of CBZ or PHT, in the MES test in mice. Pharmacokinetic studies revealed that MMIPPS (50 mg/kg) did not alter total brain concentrations of PB, but significantly elevated total brain concentrations of VPA in mice (p < 0.05). The enhanced anticonvulsant action of PB by MMIPPS in the mouse MES model and lack of any pharmacokinetic interaction between drugs make the combination of MMIPPS with PB of pivotal importance for further experimental and clinical studies. Pharmacokinetic increase in total brain VPA concentration seems to be responsible for the enhanced anticonvulsant action of VPA by MMIPPS in the mouse MES model. The combinations of MMIPPS with CBZ and PHT are neutral from a preclinical viewpoint.

Pharmacological Reports, 2011

The objective of this study was to determine the effects of 7-nitroindazole (7NI--a preferential ... more The objective of this study was to determine the effects of 7-nitroindazole (7NI--a preferential neuronal nitric oxide synthase (NOS) inhibitor) and NG-nitro-L-arginine (NNA--a non-selective NOS inhibitor) on the anticonvulsant action of pregabalin (PGB--a third-generation antiepileptic drug) in the maximal electroshock (MES)-induced seizure model in mice. Electroconvulsions were produced in mice by means of an alternating current (50 Hz, 500 V, 25 mA, ear-clip electrodes, 0.2 s stimulus duration, tonic hindlimb extension taken as the endpoint). The anticonvulsant action of PGB in the MES test was expressed as median effective doses (ED50 values) of the drug, protecting 50% of animals tested against MES-induced seizures. The acute adverse-effect potentials of PGB in combination with 7NI and NNA were evaluated in the chimney test (motor coordination), step-through passive avoidance task (long-term memory) and grip-strength test (skeletal muscular strength) in mice. 7NI (50 mg/kg, ip) significantly enhanced the anticonvulsant action of PGB by reducing the ED50 value of PGB from 145.0 mg/kg to 74.4 mg/kg (p<0.01). Similarly, 7NI at the lower dose of 25 mg/kg also potentiated the anticonvulsant action of PGB by lowering the ED50 value of PGB from 145.0 mg/kg to 117.9 mg/kg, although the results did not attain statistical significance. In contrast, NNA (40 mg/kg, ip) had no impact on the anticonvulsant effects of PGB. Moreover, none of the examined combinations of PGB with 7NI and NNA affected motor coordination, long-term memory and skeletal muscular strength in mice. Based on this preclinical study, one can conclude that 7NI significantly enhanced and NNA had no effect on the anticonvulsant activity of PGB against MES-induced seizures in mice.

Neuroscience, 2013

Botulinum neurotoxins (BoNTs) may affect the excitability of brain circuits by inhibiting neurotr... more Botulinum neurotoxins (BoNTs) may affect the excitability of brain circuits by inhibiting neurotransmitter release at central synapses. There is evidence that local delivery of BoNT serotypes A and E, which target SNAP-25, a component of the release machinery specific to excitatory synapses, can inhibit seizure generation. BoNT serotype B (BoNT/B) targets VAMP2, which is expressed in both excitatory and inhibitory terminals. Here we assessed the effects of unilateral intrahippocampal infusion of BoNT/B in the rat on intravenous pentylenetetrazol (PTZ) seizure thresholds, and on the expression of spontaneous behavioral and electrographic seizures. Infusion of BoNT/B (500 and 1000 unit) by convection-enhanced delivery caused a reduction in myoclonic twitch and clonic seizure thresholds in response to intravenous PTZ beginning about 6 days after the infusion. Handling-evoked and spontaneous convulsive seizures were observed in many BoNT/B-treated animals but not in vehicle-treated controls. Spontaneous electrographic seizure discharges were recorded in the dentate gyrus of animals that received local BoNT/B infusion. In addition, there was an increased frequency of interictal epileptiform spikes and sharp waves at the same recording site. BoNT/B-treated animals also exhibited tactile hyperresponsivity in comparison with vehicle-treated controls. This is the first demonstration that BoNT/B causes a delayed proconvulsant action when infused into the hippocampus. Local infusion of BoNT/B could be useful as a focal epilepsy model. Ó

Journal of Pharmacology and Experimental Therapeutics, 2006

Elevations in plasma serotonin (5-HT) have been implicated in the pathogenesis of cardiac and pul... more Elevations in plasma serotonin (5-HT) have been implicated in the pathogenesis of cardiac and pulmonary disease. Normally, plasma 5-HT concentrations are kept low by transporter-mediated uptake of 5-HT into platelets and by metabolism to 5-hydroxyindoleacetic acid (5-HIAA). Many abused drugs (e.g., substituted amphetamines) and prescribed medications (e.g., fluoxetine) target 5-HT transporters and could thereby influence circulating 5-HT. We evaluated the effects of amphetamines analogs [(+/-)-fenfluramine, (+/-)-3,4-methylenedioxymethamphetamine, (+)-methamphetamine, (+)-amphetamine, phentermine] on extracellular levels (i.e., plasma levels) of 5-HT and 5-HIAA in blood from catheterized rats. Effects of the 5-HT uptake blocker fluoxetine were examined for comparison. Drugs were tested in vivo and in vitro; plasma indoles were measured using a novel microdialysis method in whole blood. We found that baseline dialysate levels of 5-HT are approximately 0.22 nM, and amphetamine analogs evoke large dose-dependent increases in plasma 5-HT ranging from 4 to 20 nM. The ability of drugs to elevate plasma 5-HT is positively correlated with their potency as 5-HT transporter substrates. Fluoxetine produced small, but significant, increases in plasma 5-HT. Although the drug-evoked 5-HT concentrations are below the micromolar levels required for contraction of pulmonary arteries, they approach concentrations reported to stimulate mitogenesis in pulmonary artery smooth muscle cells. Additional studies are needed to determine the effects of chronic administration of amphetamines on circulating 5-HT.

Journal of Pharmacology and Experimental Therapeutics, 2007

Large elevations in blood serotonin (5-hydroxytryptamine; 5-HT) can produce valvular heart diseas... more Large elevations in blood serotonin (5-hydroxytryptamine; 5-HT) can produce valvular heart disease in humans and laboratory animals. In accordance, one prevailing hypothesis (i.e., the "5-HT hypothesis") suggests that 5-HT transporter substrates like fenfluramine increase the risk for valvular heart disease by elevating plasma 5-HT, secondary to the release of 5-HT from platelets. The main purpose of this study was to determine whether chronic administration of fenfluramine increases plasma 5-HT to concentrations that are associated with the development of valvular heart disease. To the best of our knowledge, this is the first study to address this issue using an in vivo microdialysis method that measures plasma 5-HT in nonhypoxic rats. We examined the effects of chronic (Ϯ)-fenfluramine and fluoxetine on plasma levels of 5-HT and its metabolite, 5-hydroxyindoleacetic acid (5-HIAA), in blood samples from conscious catheterized rats. Plasma indoles were measured by high-performance liquid chromatography with electrochemical detection in the dialysates of whole blood. The baseline plasma 5-HT level was Ͻ1.0 nM. Chronic fenfluramine (14-day minipump infusion) produced small increases in baseline plasma 5-HT (ϳ2-4-fold), whereas chronic fluoxetine had no effect. Chronic fenfluramine and fluoxetine markedly decreased whole-blood 5-HT and reduced the ability of acute fenfluramine to evoke 5-HT release. Elevations in baseline plasma 5-HT produced by chronic fenfluramine are far below the micromolar levels necessary to produce valvular heart disease. Furthermore, chronic fenfluramine reduces the ability of acute fenfluramine to increase plasma 5-HT, suggesting that the 5-HT hypothesis cannot explain the increased risk of valvular heart disease in patients treated with fenfluramine.

Journal of Pharmacology and Experimental Therapeutics, 2011

The lung provides a portal of entry for drug delivery that could be used to administer anticonvul... more The lung provides a portal of entry for drug delivery that could be used to administer anticonvulsant substances to prevent or abort seizures. Here, we demonstrate that intrapulmonary propofol hemisuccinate (PHS) rapidly confers seizure protection in various rodent chemoconvulsant models. Propofol is a powerful anticonvulsant substance at subanesthetic doses, but it is a viscous, water-immiscible oil that is not suitable for intrapulmonary administration. We found that PHS can be formulated as an aqueous solution that is well tolerated when instilled into the lung. High-dose intraperitoneally administered PHS induced loss-of-righting reflex in rats and mice. The onset of action of PHS was delayed in comparison with propofol, suggesting that conversion to propofol is required for activity. A lower dose of PHS (40 mg/kg i.p.) did not cause general anesthesia but protected against pentylenetetrazol (PTZ)-induced seizures in rats. Intrapulmonary administration of an aqueous PHS solution via a tracheal cannula at lower doses (5 and 10 mg/kg) conferred equivalent seizure protection without acute motor toxicity. In mice, intraperitoneal PHS (60-80 mg/kg) was associated with an elevation in PTZ, bicuculline, picrotoxin, and kainic acid seizure thresholds. Intratracheal PHS was markedly more potent, producing seizure threshold elevations at doses of 10 to 15 mg/kg. In the PTZ threshold model in mice, PHS was active at 5 min, maximally active at 10 min, and no longer active at 20 min. Intratracheal PHS also prolonged the onset of 4-aminopyridine-induced convulsions but did not affect the threshold for N-methyl-D-aspartate-induced convulsions. We conclude that intratracheal administration of an aqueous solution of PHS, a putative propofol prodrug, provides potent seizure protection of rapid onset and brief duration. Intrapulmonary PHS may be useful for preventing the spread of seizures or aborting seizure clusters without causing prolonged sedation.

Journal of Pharmacology and Experimental Therapeutics, 2009

Modafinil is prescribed for numerous medical conditions, but the drug's mechanism of action is un... more Modafinil is prescribed for numerous medical conditions, but the drug's mechanism of action is unclear. Here, we examined the interaction of modafinil with receptors and transporters in vitro and compared pharmacological effects of the drug with those produced by indirect dopamine (DA) agonists 1-[2-[bis(4fluorophenyl)methoxy]ethyl]-4-(3-phenylpropyl)piperazine (GBR12909) and (ϩ)-methamphetamine (METH). Modafinil was screened at various receptors and transporters using binding assays. Transporter-mediated uptake and release were examined in rat brain synaptosomes. Effects of modafinil on motor activity and neurochemistry were determined in rats undergoing in vivo microdialysis in nucleus accumbens. Of the receptors and transporters assayed, modafinil displayed measurable potency only at DA transporters (DAT), inhibiting [ 3 H]DA uptake, with an IC 50 value of 4.0 M. Accordingly, modafinil pretreatment (10 M) antagonized METH-induced release of the DAT substrate [ 3 H]1-methyl-4-phenylpyridinium. Intravenous modafinil (20 and 60 mg/kg) produced dose-dependent increases in motor activity and extracellular DA, without affecting serotonin (5-HT). Analogous results were observed for GBR12909 (1 and 3 mg/kg), whereas METH (0.3 and 1 mg/ kg) increased DA and 5-HT. Locomotor effects of all drugs were positively correlated with dialysate DA (P Ͻ 0.001). Interestingly, modafinil pretreatment reduced METH-induced ambulation and DA release. Our data show that modafinil interacts with DAT sites in rat brain, a property shared with agonist medications under investigation for treating cocaine dependence. Nondopaminergic mechanisms may also contribute to the pharmacology of modafinil. Finally, the results suggest that modafinil should be tested as an adjunct for treating METH addiction.

European Journal of Pharmacology, 2010

The aim of the study was to determine the influence of N-(ortho-carboxyanilinomethyl)-p-isopropox... more The aim of the study was to determine the influence of N-(ortho-carboxyanilinomethyl)-p-isopropoxyphenylsuccinimide [o-CAMIPPS], N-(meta-carboxyanilinomethyl)-p-isopropoxyphenylsuccinimide [m-CAMIPPS], and N-(para-carboxyanilinomethyl)-p-isopropoxyphenylsuccinimide [p-CAMIPPS] on the protective activity of four classical antiepileptic drugs (carbamazepine, phenobarbital, phenytoin and valproate) in the mouse maximal electroshock seizure model. The results indicate that all tested succinimide derivatives administered intraperitoneally at doses of 75 and 150 mg/kg significantly elevated the threshold for electroconvulsions in mice. Succinimide derivatives at a dose of 37.5 mg/kg had no effect on the threshold for electroconvulsions in mice. Furthermore, o-CAMIPPS (37.5 mg/kg) significantly reduced the anticonvulsant activity of carbamazepine, but not that of phenobarbital, phenytoin and valproate in the maximal electroshock-induced seizures in mice. Anticonvulsant efficacy of carbamazepine, phenobarbital, phenytoin and valproate in the maximal electroshock-induced seizures in mice was not changed after administration of m-CAMIPPS or p-CAMIPPS. Pharmacokinetic experiment revealed that o-CAMIPPS significantly increased total brain concentrations of carbamazepine in mice. In conclusion, the reduced anticonvulsant action of carbamazepine by o-CAMIPPS in the maximal electroshock-induced seizures, despite the increased total brain carbamazepine concentrations after combined administration of carbamazepine with o-CAMIPPS, may suggest the antagonistic interaction between drugs. The combinations of m-CAMIPPS or p-CAMIPPS with carbamazepine, phenobarbital, phenytoin and valproate were neutral from a preclinical viewpoint.

Epilepsy Research, 2012

Experimental epileptology is mainly focused on searching for some active compounds suppressing se... more Experimental epileptology is mainly focused on searching for some active compounds suppressing seizures that could become efficacious antiepileptic drugs. Accumulating evidence indicates that succinimide derivatives would be good candidates for novel antiepileptic drugs. Therefore, the aim of this study was to determine the effects of N-hydroxymethyl-p-isopropoxyphenyl-succinimide (HMIPPS) on the protective action of four classical antiepileptic drugs (carbamazepine, phenobarbital, phenytoin and valproate) in the maximal electroshock-induced seizure test in mice. Tonic hind limb extension (seizure activity) was evoked in adult male albino Swiss mice by a current (sine-wave, 25 mA, 500 V, 50 Hz, 0.2s stimulus duration) delivered via auricular electrodes. Acute adverse-effect profiles with respect to motor performance, long-term memory and skeletal muscular strength were measured along with total brain antiepileptic drug concentrations. Results indicate that HMIPPS administered intraperitoneally at 100mg/kg significantly elevated the threshold for electroconvulsions in mice (P<0.05). HMIPPS at doses of 12.5, 25 and 50mg/kg had no impact on the threshold for electroconvulsions in mice. Moreover, HMIPPS (50mg/kg) significantly enhanced the anticonvulsant activity of phenobarbital and valproate in the mouse maximal electroshock-induced seizure model by reducing their median effective doses (ED(50) values) from 23.25mg/kg to 16.82 mg/kg (P<0.01; for phenobarbital) and from 259.3mg/kg to 189.7 mg/kg (P<0.001; for valproate), respectively. In contrast, HMIPPS (50mg/kg) had no impact on the protective action of carbamazepine or phenytoin in the maximal electroshock seizure test in mice. HMIPPS (25mg/kg) significantly potentiated the anticonvulsant action of valproate by reducing its ED(50) value from 259.3mg/kg to 210.6 mg/kg (P>0.05), but not that of phenobarbital, phenytoin and carbamazepine in the mouse maximal electroshock-induced seizure model. Pharmacokinetic experiments revealed that HMIPPS did not alter total brain concentrations of phenobarbital or valproate in mice. Moreover, none of the examined combinations of HMIPPS (50mg/kg) with carbamazepine, phenobarbital, phenytoin and valproate (at their ED(50) values from the maximal electroshock-induced seizure test) affected motor coordination in the chimney test, long-term memory in the passive avoidance task, and muscular strength in the grip-strength test in mice, indicating no possible acute adverse effects in animals. In conclusion, the enhanced anticonvulsant action of phenobarbital and valproate by HMIPPS in the mouse maximal electroshock-induced seizure model, lack of pharmacokinetic interactions and no potential acute adverse effects make the combinations of HMIPPS with phenobarbital and valproate worthy of consideration for further experimental and clinical studies. The combinations of HMIPPS with carbamazepine and phenytoin are neutral from a preclinical viewpoint.

Epilepsia, 2013

Benzodiazepines are the current first-line standard-of-care treatment for status epilepticus but ... more Benzodiazepines are the current first-line standard-of-care treatment for status epilepticus but fail to terminate seizures in about one third of cases. Synaptic GABA A receptors, which mediate phasic inhibition in central circuits, are the molecular target of benzodiazepines. As status epilepticus progresses, these receptors are internalized and become functionally inactivated, conferring benzodiazepine resistance, which is believed to be a major cause of treatment failure. GABA A receptor positive allosteric modulator neuroactive steroids, such as allopregnanolone, also potentiate synaptic GABA A receptors, but in addition they enhance extrasynaptic GABA A receptors that mediate tonic inhi-bition. Extrasynaptic GABA A receptors are not internalized, and desensitization of these receptors does not occur during continuous seizures in status epilepticus models. Here we review the broad-spectrum antiseizure activity of allopregnanolone in animal seizure models and the evidence for its activity in models of status epilepticus. We also demonstrate that allopregnanolone inhibits ongoing behavioral and electrographic seizures in a model of status epilepticus, even when there is benzodiazepine resistance. Parenteral allopregnanolone may provide an improved treatment for refractory status epilepticus.

Annals of the New York Academy of Sciences, 2008

Dual dopamine (DA)/serotonin (5-HT)-releasing agents are promising candidate medications for stim... more Dual dopamine (DA)/serotonin (5-HT)-releasing agents are promising candidate medications for stimulant addiction and other disorders. However, certain 5-HT transporter (SERT) substrates are associated with development of idiopathic pulmonary arterial hypertension (IPAH) and valvular heart disease (VHD). According to the "5-HT hypothesis," SERT substrates increase the risk for developing IPAH and VHD by increasing plasma 5-HT. To test this hypothesis directly, we determined the effects of acute and chronic fenfluramine, and other SERT ligands, on plasma 5-HT in male rats. For acute treatments, rats received i.v. vehicle or test drug (0.3 and 1.0 mg/kg), and serial blood samples were withdrawn. For chronic treatments, vehicle or test drug was infused via osmotic minipump (3 and 10 mg/kg/d) for 2 weeks. On the last day of infusion, rats received i.v. fenfluramine challenge (1 mg/kg), and serial blood samples were withdrawn. Plasma 5-HT was measured using ex vivo microdialysis in whole-blood samples. Baseline plasma 5-HT was <1.0 nM. Acute injection of fenfluramine or other SERT substrates caused large (up to 24-fold) dose-dependent increases in plasma 5-HT. Chronic fenfluramine at 3 and 10 mg/kg/d produced 1.7- and 3.5-fold increases in baseline plasma 5-HT, while chronic fluoxetine had no effect. Chronic infusions of fenfluramine or fluoxetine diminished the ability of acute fenfluramine to elevate dialysate 5-HT, and both drugs markedly reduced whole-blood 5-HT. Acute fenfluramine increases plasma 5-HT to concentrations that are below the micromolar levels necessary to produce adverse cardiovascular effects. Chronic fenfluramine and fluoxetine have minimal effects on plasma 5-HT, suggesting that the increased risk for IPAH associated with fenfluramine does not depend upon elevations in plasma 5-HT.