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PubMed1982

Effects of organotin compounds on maximal electroshock seizure (MES) responsiveness in mice. I. TRI(n-alkyl)tin compounds.

Male mice (25-30 g) were injected (ip) with 0, 3.5 X 10(-6), or 17.5 X 10(-6) mol trimethyltin bromide (TMT), triethyltin bromide (TET), tri-n-propyltin chloride (TPT), or tri-n-butyltin bromide (TBT) per kg. Additional groups of mice were also injected (ip) with either 0 or 17.5 X 10(-6) mol sodium bromide (NaBr) or 17.5 X 10(-6) mol stannic bromide (SnBr4) per kg. The mice were tested with maximal electroshock seizure (MES) at 0.5, 4, 21-24, and 96 h following exposure to the organotin compounds. Mice exposed to TMT, TET, TPT, or TBT exhibited dose-dependent decreases in MES severity as evaluated by seizure-grade distributions and duration of tonic seizure phases. The tri-n-alkyltin compounds exhibited a structure-activity relationship in their ability to decreased maximal responsiveness to the MES test. In order of decreasing ability they were: TMT greater than TET greater than TPT greater than TBT. Administration of NaBr and SnBr4 did not alter MES responsiveness, indicating the essential role of the alkyl moieties of the tri-n-alkyltin compounds in producing alterations in central nervous system function.

Animals↗
PubMed1982

Effects of organotin compounds on maximal electroshock seizure (MES) responsiveness in mice. II. Tricyclohexyltin and triphenyltin.

Male mice (25-30 g) were injected (ip) with either 0, 3.5 X 10(-6), 17.5 X 10(-6), or 26.25 X 10(-6) mol/kg of either tricyclohexyltin bromide (TCT) or triphenyltin acetate (TPhT) in a corn-oil vehicle. The mice were tested for maximal electroshock seizure (MES) at 0.5, 4, 24, and 96 h following exposure to the organotin compounds, and the durations of seizure phases were measured and used to assess seizure severity. No significant changes in seizure-grade distribution, as compared to controls, were observed in any of the TCT- or TPhT-treated groups at any of the time points examined. No significant changes in the duration of seizure phases, as compared to controls, were observed in animals dose with 3.5 X 10(-6) mol/kg of TCT or TPhT at any of the time points evaluated. At 0.5 h following exposure, the mice dosed with the two higher levels of TCT or TPhT exhibited increases in MES severity. At 4 and 24 h following exposures, the mice exposed to the two higher dose levels of TPhT exhibited decreases in MES severity, followed by a recovery of normal seizure severity at 96 h. Conversely, the animals dosed with the higher dose levels of TCT exhibited at increased MES severity at 4, 24, and 96 h following exposure. These results, in combination with those in the preceeding paper (Doctor and Fox, 1982), reveal that at equimolar doses TCT And TPhT possess a different spectrum of action than the tri-n-alkyltins.

Animals↗
PubMed2005

Pharmacodynamic and pharmacokinetic interaction studies of loreclezole with felbamate, lamotrigine, topiramate, and oxcarbazepine in the mouse maximal electroshock seizure model.

PURPOSE: The study investigated the types of interactions between loreclezole (LCZ) and a variety of newly licensed antiepileptic drugs (AEDs) with different mechanisms of actions [felbamate (FBM), lamotrigine (LTG), topiramate (TPM), and oxcarbazepine (OXC)] by isobolographic analysis. METHODS: Anticonvulsant and adverse-effect profiles of combinations of LCZ with other AEDs at fixed ratios of 1:3, 1:1, and 3:1 were investigated in the maximal electroshock (MES)-induced seizures and the chimney test (as a measure of motor impairment) in mice so as to identify optimal combinations. Protective indices (PIs) and benefit indices (BIs) were calculated so that a ranking in relation to advantageous combinations could be established. RESULTS: With isobolography, it was observed that the combination of LCZ and TPM, at the fixed ratios of 1:1 and 3:1, was supraadditive (synergistic; p < 0.05), whereas LCZ with TPM at the fixed ratio of 1:3 and LCZ combined with LTG, FBM, or OXC at the fixed ratios of 1:3, 1:1, and 3:1 were associated with additive interactions. Moreover, the isobolographic analysis in the chimney test revealed that only one combination tested (LCZ and TPM at the fixed ratio of 1:1) was subadditive (antagonistic; p < 0.05), whereas the remaining combinations of LCZ with LTG, FBM, or OXC (at the fixed ratios of 1:3, 1:1, and 3:1) barely displayed additivity. However, these combinations were associated with significant pharmacokinetic interactions, in that LCZ increased brain TPM (94%), OXC (21%), FBM (46%), and LTG (8%) concentrations. In addition, brain LCZ concentrations were decreased by TPM (26%), OXC (37%), LTG (42%), and FBM (19%). None of the examined combinations between LCZ and TPM, OXC, LTG, and FBM altered long-term memory in the step-through passive-avoidance task. CONCLUSIONS: LCZ plus TPM appears to be a particularly favorable combination, based on the MES test and the chimney test. LCZ and OXC also is a favorable combination. However, these conclusions are confounded by the fact that LCZ is associated with significant pharmacokinetic interactions.

Animals↗
PubMed1976

Blockade of the tonic hindlimb extensor component of maximal electroshock and pentylenetetrazol-induced seizures by drugs acting on muscle and muscle spindle systems: a perspective on method.

Blockade of tonic hindlimb extension (THE) in the maximal electroshock seizure test was demonstrated for C-28'882-Ba, a muscle spindle suppressant, chlorpromazine, a depressant of fusimotor drive, and gallamine, a neuromuscular blocking drug. These agents also blocked THE produced by very large doses of pentylenetetrazol. Dantrolene, a muscle contraction antagonist, and MI-65-S, a muscle spindle suppressant, significantly delayed THE. The data indicate that blockade of THE may be effected at a multiplicity of loci and may not be an expression of an "anticonvulsant" effect.

Animals↗
PubMed1980

Effect of dopaminergic and GABA-ergic drugs given alone or in combination on the anticonvulsant action of phenobarbital and diphenylhydantoin in the electroshock test in mice.

In the electroshock test--taking hind-limb tonic extension as the end point--apomorphine (10 mg/kg) exerted no effect on the anticonvulsant action of phenobarbital (PB; 20 mg/kg) or diphenylhydantoin (DPH; 8 mg/kg); amantadine (25 and 100 mg/kg) decreased that of DPH, while L-DOPA (500 mg/kg) and d,l-amphetamine (10 mg/kg) potentiated the action of both anticonvulsants. Fluphenazine (4 mg/kg) had no influence on the effects of the two anticonvulsants, but haloperidol lessened that of DPH. All GABA-ergic stimulants used, i.e., gamma-hydroxybutyric acid (GHBA/250 mg/kg), baclofen (2.5 and 10 mg/kg) and aminooxoacetic acid (AOAA; 15 and 20 mg/kg) potentiated the action of PB; the action of DHP was unaffected by these drugs except for AOAA (20 mg/kg). The combined treatment with dopaminergic and GABA-ergic stimulants, being ineffective in terms of anticonvulsant activity, resulted in a marked potentiation of the action of the anticonvulsants tested in this study. The most distinct potentiation was noted in the case of PB, baclofen (1 mg/kg), and amantadine (25 mg/kg).

Amantadine↗
PubMed1982

Anticonvulsant action of phenobarbital, diazepam, carbamazepine, and diphenylhydantoin in the electroshock test in mice after lesion of hippocampal pyramidal cells with intracerebroventricular kainic acid.

The electroshock test-taking hind limb tonic extension as the end point-was carried out on the fifth day after the intracerebroventricular injections of kainic acid (KA; 0.2 microgram per mouse). The following antiepileptics were tested for the anticonvulsant effects both in naive and KA-lesioned mice: phenobarbital (20 mg/kg), diazepam (8 mg/kg), carbamazepine (15 mg/kg) and diphenylhydantoin (10 mg/kg), all drugs being injected intraperitoneally 60 min before electroconvulsions. It was found that the protective effects of phenobarbital and diazepam were distinctly reduced in KA-lesioned animals when compared to naive mice. However, both carbamazepine and diphenylhydantoin protected KA-injected and control animals to a similar degree. Further, intracerebroventricular injections of KA resulted in the substantial loss of pyramidal cells in the whole CA3 field of the hippocampus. It is suggested that the intact hippocampus is necessary for the development of the full anticonvulsant effects of phenobarbital and diazepam, whilst the site of action of carbamazepine and diphenylhydantoin is independent of the hippocampus.

Animals↗
PubMedDate not supplied

Interaction of felbamate with several other antiepileptic drugs against seizures induced by maximal electroshock in mice.

The anticonvulsant effects of felbamate (FBM) alone or in combination with phenytoin (PHT), carbamazepine (CBZ), valproate (VPA), or phenobarbital (PB) were investigated against maximal electroshock (MES) seizures in mice. Nonprotective doses of the prototype antiepileptic drugs (AEDs) enhanced the protective effects of FBM against electrically induced seizures, as shown by significant reduction of FBM ED50 values. Toxicity as determined by rotorod test was not significantly potentiated, however, and the protective index (PI = TD50/ED50) of FBM was increased by > 100% for each AED interaction. The increase in anticonvulsant potency of FBM after its combination with nonprotective doses of AEDs could not be accounted for by a pharmacokinetic mechanism.

Animals↗
PubMed1996

Anticonvulsant activity of phenobarbital and valproate against maximal electroshock in mice during chronic treatment with caffeine and caffeine discontinuation.

We evaluated the protective activity (expressed as ED50 values in mg/kg of phenobarbital (PB, 120 min before testing) and valproate (30 min) alone or combined with caffeine in male mice with seizures induced by maximal electroshock (MES). Both antiepileptic drugs (AEDs) were administered by intraperitoneal (i.p.) injection in a single dose to mice receiving intraperitoneal caffeine either in a single dose 30 min before the test or as pretreatment every 12 h for 3 and 14 days. In addition, we determined the ED50 values of the AEDs 24 and 72 h after 14-day treatment with caffeine. Finally, we studied the influence of a challenge dose of caffeine, injected in mice 24 and 72 h after 14 days of treatment with caffeine, on the protective activity of PB or VPA. Caffeine in a single dose of 23.1 mg/kg reduced the anticonvulsant effect of PB. Its protective activity was further impaired after 3 and 14 days of caffeine treatment. The ED50 for VPA was significantly increased both by the single dose of caffeine and by chronic treatment. The anticonvulsant activity of PB and VPA measured 24 and 72 h after 14-day treatment with caffeine did not differ from control values, but a challenge dose of caffeine injected 24 or 72 h after daily injections for 14 days resulted in a significant reduction in the protective activity of both AEDs. Measurement of the total plasma levels of caffeine, VPA, and PB did not suggest pharmacokinetic interactions as an explanation for our results. Our results indicate that chronic caffeine exposure may progressively reduce the antiepileptic potency of VPA and PB.

Animals↗
PubMed1999

Muscarinic receptors mediate carbachol-induced inhibition of maximal electroshock seizures in the nucleus reticularis pontis oralis.

PURPOSE: Previous reports from this laboratory indicated a role for N-methyl-D-aspartic acid (NMDA) and gamma-aminobutyric acid (GABA) receptors among the neuronal mechanisms of the nucleus reticularis pontis oralis (RPO) that regulate the tonic hindlimb extension (THE) component of maximal electroshock seizures (MESs) in rats. This study was intended to determine the role of cholinergic mechanisms in the RPO regulation of THE. METHODS: Rats were surgically prepared with microinjection guide cannulas for the focal administration of drug solutions directly into the RPO. MES was induced with corneal electrodes. RESULTS: RPO microinjection of carbachol significantly inhibited the incidence of THE. RPO microinjection of atropine by itself had no effect on the seizure response but significantly antagonized the anticonvulsant effect induced by RPO microinjection of carbachol. The selective nicotinic agonist dimethylpiperizinium (DMPP) by itself had no effect on THE. RPO microinjection of 10 ng pertussis toxin by itself had no effect on THE but significantly antagonized the anticonvulsant effect induced by RPO microinjection of carbachol. CONCLUSIONS: RPO microinjection of carbachol inhibited the THE component of MESs in rats. The carbachol effect appeared to be mediated by muscarinic receptors as the anticonvulsant activity was antagonized by atropine, and the selective nicotinic agonist DMPP induced no anticonvulsant activity. Because pertussis toxin acts to inhibit muscarinic receptor-linked G proteins, the pertussis toxin antagonism of carbachol also supports a muscarinic mechanism of action.

Animals↗
PubMed2006

Pharmacodynamic and pharmacokinetic characterization of interactions between levetiracetam and numerous antiepileptic drugs in the mouse maximal electroshock seizure model: an isobolographic analysis.

PURPOSE: Approximately 30% of patients with epilepsy do not experience satisfactory seizure control with antiepileptic drug (AED) monotherapy and often require polytherapy. The potential usefulness of AED combinations, in terms of efficacy and adverse effects, is therefore of major importance. The present study sought to identify potentially useful AED combinations with levetiracetam (LEV) METHODS: With isobolographic analysis, the mouse maximal electroshock (MES)-induced seizure model was investigated with regard to the anticonvulsant effects of carbamazepine (CBZ), phenytoin, phenobarbital (PB), valproate, lamotrigine, topiramate (TPM), and oxcarbazepine (OXC), administered singly and in combination with LEV. Acute adverse effects were ascertained by use of the chimney test evaluating motor performance and the step-through passive-avoidance task assessing long-term memory. Brain AED concentrations were determined to ascertain any pharmacokinetic contribution to the observed antiseizure effect. RESULTS: LEV in combination with TPM, at the fixed ratios of 1:2, 1:1, 2:1, and 4:1, was supraadditive (synergistic) in the MES test. Likewise, the combination of LEV with CBZ (at the fixed ratio of 16:1) and LEV with OXC (8:1 and 16:1) were supraadditive. In contrast, all other LEV/AED combinations displayed additivity. Furthermore, none of the investigated LEV/AED combinations altered motor performance and long-term memory. LEV brain concentrations were unaffected by concomitant AED administration, and LEV had no significant effect on brain concentrations of concomitant AEDs. CONCLUSIONS: These preclinical data would suggest that LEV in combination with TPM is associated with beneficial anticonvulsant pharmacodynamic interactions. Similar, but less profound effects were seen with OXC and CBZ.

Animals↗
PubMed1991

Vagal stimulation reduces the severity of maximal electroshock seizures in intact rats: use of a cuff electrode for stimulating and recording.

J. Zabara showed that repetitive vagal stimulation (VS) prevents or ameliorates convulsive seizures in dogs. We have studied the effects of VS on maximal electroshock seizures (MES) in intact rats: (1) A 5 wire cuff electrode was developed for stimulating and recording from the vagus. Compound action potentials (AP) were recorded and strength-duration curves obtained for A and C fibers. There is a monotonic relationship with a negative slope between heart rate (HR) and AP amplitude. C fibers remain excitable for 25 days after cuff implant. (2) The anticonvulsant efficacy of VS is directly related to the fraction of vagal C fibers stimulated and the frequency of stimulation. (3) The anticonvulsant efficacy of VS has been established using two rat models of human epilepsy. VS abolishes the extensor component of the tonic phase of a MES and shortens or prevents tonic seizures induced by pentylenetetrazol (PTZ). (4) VS appears to act via release of large quantities of the inhibitory mediators GABA and glycine throughout large volumes of the brain. (5) It is rational to test VS in man as a treatment for intractable seizures.

Action Potentials↗
PubMed1981

Effects of withdrawal from long-term diphenylhydantoin treatment on audiogenic and maximal electroshock-induced seizures in rats.

Rats withdrawal from long-term diphenylhydantoin treatment (DPH) were tested for their sensibility to convulsant stimuli. Animals were more sensitive to convulsions elicited by maximal electroshock and sound, respectively, at 48 and 72 h after drug removal. These results suggest that long-term DPH treatment might develop a central nervous system supersensitivity state.

Acoustic Stimulation↗
PubMed2006

Electroshock as a form of violence against women.

This article reframes electroconvulsive therapy as a form of violence against women. Drawing on women's testimony and on scientific research, it establishes that this "treatment," which is overwhelmingly given to women, results in extensive cognitive and physical impairment. Correspondingly, it functions and is experienced as a form of assault and social control, not unlike wife battery. Emergent themes include electroshock as life destroying, a sign of contempt for women, punishment, a means of enforcing sex roles, a way to silence women about other abuse, an assault, traumatizing for those who undergo it and those forced to witness it.

Battered Women↗
PubMed1980

Differential antagonisms of anticonvulsants to various components of maximal seizures induced by electroshock or pentylenetetrazol in mice.

Effects of antiepileptic drugs on various components (TF: tonic extension of forelimb, TH: tonic extension of hindlimb and CL: clonic convulsions or MCL: myoclonus) of maximal seizures induced by electroshock or pentylenetetrazol in mice were examined in order to classify these drugs. In addition, experiment was conducted similarly on the new anti-convulsant agent, 3-sulfamoylmethyl-1,2-benzisoxazole (AD-810), in order to assess this compound on the basis of the results with clinically useful antiepileptic drugs. From the results obtained in the present study, irrespective of the method, i.e. chemically or electrically induced seizures, anticonvulsant drugs tested can be classified into four main groups; 1) drugs (trimethadione, ethosuximide, nitrazepam, diazepam, erthotoin and metharbital) with an effect to antagonize all the whole seizure components. (TF, TH and CL or MCL) in an almost same antagonism, 2) drugs (phenacemide, dipropylacetate, pheneturide, acetylpheneturide and phenobarbital) which inhibit all forms of seizures at relatively dissociated doses for the prevention of each component of seizures, 3) drugs (diphenylhydantoin and carbamazepine) which selectively abolish both components (TF and TH) of tonic seizures, and 4) drugs (acetazolamide, sulthiame and primidone) exclusively blocking TH of tonic seizures. AD-810 demonstrated an antagonistic effect on tonic seizures but no on clonic ones with the same manner as seen with diphenylhydantoin and carbamazepine.

Animals↗
PubMed2003

Anticonvulsant action of celecoxib (alone and in combination with sub-threshold dose of phenytoin) in electroshock induced convulsion.

Celecoxib is a selective cyclooxygenase-2 (COX-2) inhibitor, COX-2 has been shown to be upregulated by convulsive nerve activity. Various earlier studies have given conflicting reports on the effect of COX inhibitors on seizures. This study investigates the effect of pretreatment with celecoxib alone, or in combination with phenytoin, on electroshock-induced convulsions. Both percentage protection (i.e., the percentage of animals not showing Tonic Hind Limb Extension [THLE] when a fixed dose of current is administered) and CC50 (i.e., the threshold current inducing THLE in 50%) was determined using a technoconvulsometer. Celecoxib and phenytoin were administered 1 and 2 h, respectively, prior to the experiments. When administered alone, celecoxib showed an increase in percentage protection at increasing doses, with maximum percentage protection (66.6%) occurring at a 30 mg/kg-1 dose. The ED25 value of celecoxib was calculated to be 8.03 mg/kg-1. The CC50 values for the treatment groups were significantly increased compared with the control group (CC50 values for control, celecoxib 10 mg/kg-1, celecoxib 20 mg/kg-1 and celecoxib 30 mg/kg-1, respectively, were 36.3, 49.12, 100.3 and 125.02 mA). An increase in percentage protection was noted when celecoxib 8.03 mg/kg-1 was coadministered with phenytoin 6 mg/kg-1 (66.6% with the combination vs. 16.6% when administered individually). A significant increase was noted in the CC50 value in a combination regimen (CC50 = 79.06) compared with either drug administered alone (CC50 = 49.12 with celecoxib 8.03 mg/kg-1 and 62.06 with phenytoin 6 mg/kg-1). This study may stimulate further interest in the role of COX-2 inhibitors in the modulation of seizure activity.

Animals↗
PubMed1998

Insulin impairs the anticonvulsive activity of carbamazepine against maximal electroshock-induced seizures in mice.

In view of the data indicating that insulin can modify penetration of some drugs across cell membranes and tissue barriers, particularly the blood-brain barrier, the aim of the present study was to evaluate the effect of insulin on both the anticonvulsant activity and the brain concentration of carbamazepine in mice suffering from seizures induced by maximal electroshock. The antiepileptic drug was administered per os in single doses either alone or in combination with insulin given as single intraperitoneal injections. To assess the anticonvulsant activity of carbamazepine the ED50 values were calculated. The results indicate that insulin given in doses up to 2 units/kg did not affect the convulsive threshold, whereas insulin applied at 2 units/kg led to a significant reduction in the anticonvulsant activity of carbamazepine, as judged by an increase in the ED50 value from 16.2 to 41.3 mg/kg. This effect was accompanied by the marked reduction in both the brain and blood concentrations of the drug. It is likely, therefore, that the inhibitory activity of insulin on the anticonvulsive function of carbamazepine is related not only to the effect of the former on the blood-brain transport of the latter, but also to insulin-induced modulation of the serum concentration of the drug.

Animals↗
PubMed1975

Correlation between brain monoamine levels and postictal coma following electroshock.

Duration of postictal coma following maximal electroshock seizure and monoamine levels in the whole brain were measured in mice. Pretreatment with intraperitoneal alpha-methyl-p-tyrosine (alpha-MT), 5-hydroxytryptophane (5-HTP), or intraventricular 6-hydroxydopamine (6-OHDA) prolonged the coma duration, whereas p-chlorophenylalanine (PCPA) did not affect the coma, and L-DOPA tended to shorten the coma and counteracted the effect of alpha-MT. When the shock was repeated five times with one hour intervals, the duration of coma was progressively increased being accompanied by elevated serotonin (5-HT) and 5-hydroxyindole acetic acid (5-HIAA) levels in the brain. In alpha-MT treated group, a striking parallelism was remarked between coma prolongation and norepinephrine (NE) or dopamine (DA) reduction. These data suggest that prolongation of postictal coma is correlated with reduced NE and DA levels and/or with elevated 5-HT and 5-HIAA levels in the brain.

Animals↗
PubMed2001

Synergistic protection of allopregnanolone and phenobarbital against maximal electroshock seizures in mice.

AIM: To examine the interactions of allopregnanolone and phenobarbital for the protection against seizures. METHODS: The protective activity of allopregnanolone and/or phenobarbital against seizures was studied in the C57 mice, using the maximal electroshock seizure (MES) test. The modulations by allopregnanolone and/or phenobarbital at the GABA(A) receptor were also characterized using the [3H]flunitrazepam binding in the membrane preparation of mouse cerebral cortex. RESULTS: Pretreatment with phenobarbital produced a dose-dependent protective effect against seizures. The ED50 value of phenobarbital was 2.61 (95 % confidence limits: 1.59 - 4.26) mg . kg-1. Likewise, the ED50 value of allopregnanolone was 0.11 (0.06 - 0.18) mg . kg-1. The combination of allopregnanolone and phenobarbital (1:20) resulted in an ED50 value of 0.73 (0.44 - 1.21) mg . kg-1 with the Q value smaller than 1. In measuring the enhancement of [3H]flunitrazepam binding, we found that the pattern for the concentration-effect curves of phenobarbital with or without allopregnanolone was consistent with that of the theoretical curves of functional synergism. CONCLUSION: There was a synergism between allopregnanolone and phenobarbital for the protective activity against seizures. Also there was a functional synergism between these two agents for the enhancement of [3H]flunitrazepam binding to the GABAA receptor complex in the brain.

Animals↗