Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0036572 (seizures)
 80,221 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The convulsant profile of lindane was investigated in OF1 and NMRI mice lines in relation to other convulsants acting at the GABAA and NMDA receptor complexes. Thus, a specific GABA-gated chloride channel blocker, PTX, a GABAA receptor antagonist, PTZ, and an excitatory amino acid receptor agonist, NMDA, were used. Antagonism of the convulsant effects of each of these drugs was investigated with (+)MK-801, a blocker of the NMDA-operated cation channel, and with nifedipine, a voltage-dependent calcium channel antagonist. While no differences in potency for PTX or PTZ to induce seizures were observed between OF1 and NMRI mice, lindane was approximately 80 and 90% more potent in its ability to induce seizures and lethality, respectively, in OF1 than in NMRI mice. Brain lindane concentrations at the moment of convulsion, measured after ED100 doses of lindane (400 and 200 mg/kg for NMRI and OF1 mice, respectively), did not differ between OF1 and NMRI mice, suggesting that the different potency of lindane between these mouse lines is a consequence of pharmacokinetic factors. Furthermore, (+)MK-801 antagonized seizures induced by either lindane, PTX or PTZ with similar potencies in both mouse lines. These results, coupled with the different pharmacokinetics of lindane in OF1 and NMRI mice, suggest that the distinct effects of lindane in these mice are not mediated by different activities at either NMDA or GABAA receptor complexes. Nonetheless, nifedipine antagonized lindane-induced seizures with a three-fold higher potency in NMRI than in OF1 mice. In contrast, nifedipine failed to antagonize PTX and PTZ convulsions in both OF1 and NMRI mice. These results suggest that besides the GABAA receptor complex other mechanisms related to calcium mobilization may be involved in the convulsant action of lindane.
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PMID:Lindane-induced convulsions in NMRI and OF1 mice: antagonism with (+)MK-801 and voltage-dependent calcium channel blockers. 128 May 23

1. The convulsant activity of the calcium voltage L-channel agonist Bay k 8644 was studied in genetically epilepsy prone DBA/2 mice. 2. Seizures were induced by intracerebroventricular injection of Bay k 8644. 3. These seizures were reversed by some calcium channel blockers such as dihydropyridines, some excitatory amino acid antagonists such as 2-amino-7-phosphonoeptanoate and CPPene, 2-chloro-adenosine, some anticonvulsant drugs such as magnesium valproate, diazepam and clonazepam and two kappa opioid agonists (U-50488H and U-54494A). 4. The remaining antiepileptic drugs (carbamazepine, phenytoin, phenobarbital and trimethadione) were ineffective in this respect. Other anticonvulsant compounds such as dizocilpine (MK 801), ketamine and drugs enhancing GABAergic transmission did not significantly affect the clonic phase of the seizures induced by Bay k 8644. 5. These results show that Bay k 8644 seizures are relatively resistant to some anticonvulsant compounds. The role of some neurotransmitters on seizures induced by Bay k 8644 is discussed.
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PMID:Effects of antiepileptic drugs, calcium channel blockers and other compounds on seizures induced by activation of voltage-dependent L calcium channel in DBA/2 mice. 128 40

The treatment and management of neuroleptic-resistant schizophrenic patients, who comprise 5 to 25 percent of all patients with that diagnosis, are major problems for psychiatry. In addition, another large group of schizophrenic patients, perhaps 5 to 20 percent, are intolerant of therapeutic dosages of neuroleptic drugs because of extrapyramidal symptoms, including akathisia, parkinsonism, and tardive dyskinesia. Because about 60 percent of neuroleptic-resistant schizophrenic patients respond to clozapine and a large percentage of neuroleptic-intolerant patients are able to tolerate clozapine, it should be considered the treatment of choice for such patients until other therapies are proven to be superior. A trial of clozapine alone should usually be continued for up to 6 months before it is terminated or supplemental agents are tried. Plasma levels of clozapine may be useful to guide dosage. The major side effects of clozapine are granulocytopenia or agranulocytosis (1%-2%) and a dose-related increase in the incidence of generalized seizures. Psychosocial treatments such as education of the patient and the family about the nature of the illness, rehabilitation programs, social skills training, and assistance in housing are generally needed to obtain optimal benefit from clozapine, as with other somatic therapies. If clozapine is unavailable, unacceptable, or not tolerated, a variety of approaches may be employed to supplement typical antipsychotic drugs for patients who do not respond adequately to these agents alone. These include lithium; electroconvulsive therapy; carbamazepine or valproic acid; benzodiazepines; antidepressant drugs; reserpine; L-dopa and amphetamine; opioid drugs; calcium channel blockers; and miscellaneous other pharmacologic approaches. The evidence for the efficacy of these ancillary somatic therapies in treatment-resistant patients is relatively weak. Polypharmacy should be tried only for discrete periods and with clear goals. If these are not achieved, supplemental medications should be discontinued. Psychosurgery is not a recommended alternative at this time.
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PMID:Treatment of the neuroleptic-nonresponsive schizophrenic patient. 135 41

Four children with Landau-Kleffner syndrome were studied over a six year period. They presented with acquired aphasia, epilepsy, and focal or generalized EEG discharges which were exacerbated during sleep. In addition, cerebral angiography demonstrated isolated arteritis of some branches of the carotid arteries in all cases. Computed tomographic and magnetic resonance images were normal. Nicardipine in a dose of 1 to 2 mg/kg/day, added to conventional anticonvulsant drugs provided effective supplementary control of seizures, of paroxysmal EEG discharges, and of language and behavioural disturbances, even several years after the onset of the disorder and in patients whose response to other medications, including steroids, had been poor. Interruption of nicardipine administration was followed by relapse of the language disorder. Repeat angiography was performed in all four patients and showed recanalization of obstructed vessels in two cases. Focal cerebral vasculitis may be the pathogenesis of the Landau-Kleffner syndrome and calcium channel blockers such as nicardipine may be effective and specific therapy.
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PMID:Is cerebral arteritis the cause of the Landau-Kleffner syndrome? Four cases in childhood with angiographic study. 137 38

Intravenous injection of N-methyl-D,L-aspartic acid (NMDLA) into mice produces characteristic convulsions followed by death. The present study was designed to determine the degree of blockade of these seizures/mortality by compounds acting at various subsites on the N-methyl-D-aspartic acid (NMDA) receptor complex (competitive and noncompetitive antagonists, as well as inhibitors of the strychnine-insensitive glycine subsite, and Zn++ subsite agonists), and also calcium channel blockers, clinically used anticonvulsants, plus selected compounds with activities or structures similar to specific agents chosen. Activity among compounds was correlated to in vitro potency regarding inhibition of binding of MK801 to the ionic channel subsite associated with the NMDA receptor. Furthermore, all compounds were examined for antiseizure properties with respect to tonic hindlimb extension elicited by maximal electroshock (MES) and clonus induced by pentylenetetrazol (PTZ). Drugs were subsequently classified according to their spectra of efficacy in these tests. The following characteristics emerged: 1) agents active at all 3 NMDA mechanisms (convulsions/mortality/MK801 binding) plus MES and PTZ, were MK801 and CPP [3-(2-carboxypiperazin-4-yl) propyl-1-phosphonic acid]; 2) active at all the NMDA mechanisms and MES were ketamine and dextromethorphan; 3) active against NMDLA-induced convulsions/mortality, MES and PTZ, but not MK801 binding, were doxepin, desipramine and diazepam; 4) active against NMDLA-induced convulsions/mortality and MES were des-Me-doxepin, flunarizine and remacemide; 5) active against NMDLA-induced convulsions/mortality and PTZ was nisoldipine; 6) active against only NMDLA-induced convulsions/mortality were chlorpheniramine and iproniazid; 7) active in the MES and PTZ tests were phenobarbital, pentobarbital and valproate; 8) active in the MES test alone were phenytoin and carbamazepine; 9) active against PTZ only was ethosuximide; 10) active only in the in vitro MK801 binding assay were HA966, 7-Cl-kynurenate and AP7 (2-amino-7-phosphonoheptanoic acid); and 11) no demonstrable actions had AP4 (2-amino-4-phosphonobutyric acid) and mianserin. In conclusion, inhibition of NMDLA-induced convulsions/mortality in vivo is not necessarily correlated to a noncompetitive displacement of MK801 binding to NMDA receptor sites in vitro, nor is inhibition of NMDA-elicited convulsions/mortality correlated with a specific ability of a compound to inhibit either MES or PTZ seizures.
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PMID:Classification of compounds for prevention of NMDLA-induced seizures/mortality, or maximal electroshock and pentylenetetrazol seizures in mice and antagonism of MK801 binding in vitro. 145 42

Only flunarizine (40 mg/kg, i.p.) significantly raised the threshold for electroconvulsions in mice (ear-clip electrodes, 0.2 sec stimulus duration, tonic hindlimb extension as an endpoint), whilst nicardipine and nimodipine (up to 80 mg/kg) was ineffective in this respect. Further, flunarizine (10 and 20 mg/kg) potentiated the efficacy of carbamazepine and valproate against maximum electroshock (50 mA)-induced seizures and, in the dose of 20 mg/kg, enhanced that of diphenylhydantoin. In addition, this calcium channel inhibitor was without influence upon the total levels of these antiepileptics in plasma. Nicardipine (5 and 10 mg/kg) and nimodipine (10 and 20 mg/kg) increased the protective potential of carbamazepine and nimodipine (20 mg/kg) also decreased the ED50 of diphenylhydantoin against maximum electroshock. However, nicardipine distinctly increased the level of carbamazepine in plasma, whilst nimodipine did not affect the level of both antiepileptics in plasma. The combined treatment of calcium channel inhibitors and antiepileptic drugs, providing a 50% protection against maximum electroshock, did not significantly change the motor performance of mice in the chimney test, when compared with antiepileptic drugs, given alone at their ED50s, against maximum electroshock-induced convulsions. The present results give further support to the idea of the combined use of some calcium channel inhibitors and antiepileptic drugs in the treatment of human epilepsy.
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PMID:Influence of flunarizine, nicardipine and nimodipine on the anticonvulsant activity of different antiepileptic drugs in mice. 147 24

The use of magnesium sulfate (MgSO4) as an anticonvulsant is controversial. Status epilepticus was induced in 0.5% halothane-anesthetized Wistar rats with a threshold (90 mg/kg) or suprathreshold (200 mg/kg) dose of intravenous (i.v.) pentylenetetrazol (PTZ) under stereotactic hippocampal depth electrode monitoring. Fifteen minutes after seizure induction, the maximum hemodynamically tolerated dose of MgSO4 (10 mg/kg/min in 22 min) was administered i.v. MgSO4 was ineffective in altering seizure discharge. A subgroup of nine animals received hypertonic mannitol before MgSO4 to open the blood-brain barrier (BBB) to facilitate Mg2+ CNS penetration. Again MgSO4 was ineffective in attenuating epileptic activity. These results support the contention that MgSO4 is not an effective treatment for status epilepticus. We hypothesize that because Mg2+ blocks Ca2+ influx into the neuron through the N-methyl-D-aspartate (NMDA) receptor-operated calcium channel in a voltage-dependent manner it would be ineffective in neurons that are continuously depolarizing as in status epilepticus.
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PMID:Effects of magnesium sulfate on pentylenetetrazol-induced status epilepticus. 183 Nov 20

1. Chronic treatment with the dihydropyridine calcium channel antagonist, nitrendipine, given concurrently with ethanol, prevented the ethanol withdrawal syndrome in mice, even though the chronic nitrendipine treatment was stopped 24 h or 48 h before the withdrawal testing. 2. This effect was seen in two strains of mice with different methods of ethanol administration. Nitrendipine was effective when given for two weeks but not after only two days' treatment. 3. Two other dihydropyridine calcium antagonists, nimodipine and PN 200-110, given chronically with ethanol, also prevented the withdrawal syndrome. The tests were again made 24 h after the last administration of dihydropyridine. 4. The chronic nitrendipine treatment also prevented the rise in the number of central dihydropyridine binding sites that occurs on chronic ethanol administration. 5. Chronic administration of nitrendipine alone did not cause any withdrawal behaviour. 6. Chronic nitrendipine treatment did not affect the seizure threshold to bicuculline in mice that were not given ethanol. 7. Whole brain concentration measurements showed that the effects were not due to residual nitrendipine in the CNS at the time of withdrawal testing or to differences in central ethanol concentrations during the treatment. 8. It is suggested that the results provide evidence for a functional role for dihydropyridine-sensitive calcium channels in ethanol dependence.
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PMID:Chronic dihydropyridine treatment can reverse the behavioural consequences of and prevent adaptations to, chronic ethanol treatment. 183 95

An examination of the cellular and molecular mechanisms of neuronal cell damage may lead to the design of pharmacologic interventions during presumed or actual fetal asphyxia. Hypoxia-ischemia in its severest form results in insufficient adenosine 5'-triphosphate production. The most important effect of this is failure of adenosine 5'-triphosphate-dependent membrane functions, which maintain ionic homeostasis, that is, ionic pumping. There is K+ efflux and Na+ influx across the cell membrane, depolarization of the cell membrane, opening of the voltage-dependent calcium channels, and entrance of Ca++ into the cell. Cytosolic Ca++ is also increased by Ca++ efflux from the mitochondria and the sarcoplasmic reticulum. Ca++ is a toxin in high cytosolic concentrations; it activates phospholipases A and C, which cause membrane breakdown and release of free fatty acids, including arachidonic acid. The membrane is damaged, lysis occurs, and the neuron dies. High cytosolic Ca++ also causes release of excitatory amino acids (especially glutamate), which overwhelm the suppressant neurotransmitters, causing seizures, increased metabolism, and aggravation of the insufficient adenosine 5'-triphosphate availability. Thromboxane A2 is generated from arachidonic acid, increasing smooth muscle tone and thereby worsening the ischemia. Cyclooxygenase activity also results in formation of oxygen-free radicals that contribute to cell membrane damage, lysis, and death. Possibilities for pharmacologic interventions include (1) calcium channel blockers and antagonists, (2) excitatory neurotransmitter blockers, (3) oxygen-free radical scavengers (e.g., superoxide dismutase), (4) cyclooxygenase or prostaglandin synthesis inhibitors, and (5) seizure suppressants (e.g., phenobarbital). Some of these treatments have been shown experimentally to limit neuronal death in the adult and fetus, and after more investigative work they may be applicable to clinical practice.
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PMID:Mechanisms of asphyxial brain damage, and possible pharmacologic interventions, in the fetus. 190 82

Nifedipine (2.5-10 mg/kg) and verapamil (2.5 and 10 mg/kg) offered some protection against pentylenetetrazol (100 and 130 mg/kg)-induced seizure activity in mice. No protection was provided by diltiazem (1.25-10 mg/kg) in this model of experimental epilepsy. Repeated administration of calcium channel blockers (CCBs) in doses of 5 and 10 mg/kg twice daily for three days resulted in no protective effect against pentylenetetrazol. Regarding electroconvulsions, nifedipine (2.5-10 mg/kg) showed the best anticonvulsive action--for instance, in the dose of 10 mg/kg (60 min--treatment time) it elevated the threshold for electroconvulsions from 7.1 to 10.5 mA. Diltiazem (up to 10 mg/kg) and verapamil (up to 20 mg/kg) were considerably less potent in this respect. After repeated administration, only nifedipine (5-10 mg/kg) retained its protective action against electroconvulsions.
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PMID:Influence of calcium channel blockers on pentylenetetrazol and electroshock-induced convulsions in mice. 194 38


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