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Query: UMLS:C0036572 (seizures)
 80,221 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Epilepsy-like convulsive seizures have been induced by cholera toxin administration into the rat amygdaloid complex. Between the 8th and 48th hr after the administration, rhythmic spike discharges (1--3 spikes/sec) were electroencephalographically observed bilaterally in the amygdaloid complexes, and rats exhibited abnormal behaviors such as running, jumping, tail lifting, rearing, vocalization aggressive behavior, facial twitching and increased salivation. During these stages, high voltage spikes were intermittently observed with generalized convulsive seizures. Duration of the seizure was 1--2 min and the incidence was 0--6 times/hr. At 48 hrs after the administration or thereafter, convulsive seizures disappeared and electroencephalographic abnormalities were gradually normalized. Occasional rhythmic spike discharges, however, were observed more than 168 hrs after the administration. Since autoradiographic observations with 125I-labeled cholera toxin revealed that the injected toxin does not spread out at all from the injected site, the use of this toxin seems to be an ideal procedure to produce micro-epileptogenic foci. Cyclic AMP content as well as adenylate cyclase activity in the ipsilateral amygdaloid complex was significantly increased during preconvulsive and convulsive states. The administration of 5 x 10(-8) moles of dibutyryl cyclic AMP through the cannula implanted into the amygdaloid complex also induced behavioral and electroencephalographic abnormalities similar to those found in the cholera toxin-treated animals. These results suggest that cyclic AMP and/or cyclic AMP dependent neuronal mechanisms may play a significant role in the establishment of epileptogenic focus. Possible use of this animal model for the study of anti-epileptic drugs are also suggested.
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PMID:[Cholera toxin induced epileptogenic focus--special reference to cyclic AMP metabolism and epileptogenic focus (author's transl)]. 23 Aug 51

In experiments on male albino rats and mice a study is made of the effects of imidazol which is a phosphodiesterase stimulator, papaverine which inhibits phosphodiesterase and histamine which stimulates adenylate cyclase, on the convulsive-seizure reactivity. The substances are introduced intraventricularly and intracerebroventricularly, imidazol also intraperitoneally in different doses and at different intervals before the convulsive agent. Electrical, pentylenetetrazol (Cor) and strychnine convulsion models are used. The effect of imidazol on the spontaneous cortical bioelectrical activity is studied throuth its i. v. administration in rabbits. Imidazol markedly increases the convulsive reactivity, and in large doses it alone results in electrographic and motor convulsions. Paperine slightly lowers the convulsive-seizure reactivity only in pentylenetetrazol convulsions. The results obtained and their comparison with the results of previous experiments of ours with other drugs affecting the cyclic adenosinemonophosphate (cAMP) system, such as lithium, haloperidol, caffeine and theophyline, do not permit to assume a considerable significance of the influence of these substances (in the doses tested) on the cAMP system in the mechanisms of their effects on the convulsive-seizure reactivity.
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PMID:Experimental study of the effects of imidazol, papaverine and histamine on convulsive-seizure reactivity. 101 6

Patients with medically intractable temporal lobe epilepsy (TLE) undergo medial temporal lobectomy with hippocampectomy for one of two reasons. (1) A lesion (tumor or arteriovenous malformation) adjacent to, but not invasive of, the hippocampus, results in the removal of the lesion and adjacent hippocampus in order to ensure a tumor-free margin. This group will be referred to as tumor-related TLE (TTLE) patients. (2) The operation is performed when depth electrode recordings and other evaluative techniques point to the hippocampus as the focus of seizure initiation. This group will be referred to as cryptogenic TLE (CTLE) patients. Analysis of the hippocampi of these two groups of patients reveals that the TTLE hippocampus is quite similar to that of autopsy subjects in its chemical neuroanatomy. However, the dentate gyrus of the CTLE patients shows considerable morphological and cytochemical reorganization. This reorganization is characterized by a number of features. (1) There is a loss of granule cells which occurs either as a patchy loss and/or a thinning of the granule cell layer. (2) Remaining granule cells which contain dynorphin appear to produce recurrent collaterals into the inner molecular layer of the dentate gyrus. (3) In the subgranular region of the hilus (the polymorphic layer) there is a selective loss of interneurons immunoreactive for somatostatin, neuropeptide Y and substance P. (4) There appears to be an increase in fibers immunoreactive for somatostatin and neuropeptide Y which extend throughout the dentate molecular layer. Somatostatin fibers being less numerous than neuropeptide Y fibers (5). The distributions of a number of neurotransmitter receptors also show striking reorganization in the dentate gyrus of the CTLE hippocampus. (6) Second messenger systems protein kinase C and adenylate cyclase, and Na+, K(+)-ATPase activity, as determined by ouabain binding, is increased in the molecular layer of CTLE. This remodeling of the CTLE hippocampus may hold the key to the mechanisms of hyperexcitability of the granule cells in the hippocampus of this group, and consequently the generation of seizures. The removal of the hippocampus in CTLE patients results in good control of seizures, whereas removal of hippocampi that do not show such reorganization, in a group of patients classified as atypical CTLE patients, results in inadequate seizure control. These findings suggest a complex series of processes in converting the properly regulated granule cells into hyperexcitable ones.
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PMID:Neurotransmitters and their receptors in human temporal lobe epilepsy. 136 31

l-Tetrahydroberberine-d-camphor sulfonate (THB-CS) possessed an inhibitory effect on apomorphine-induced chewing movement in a similar manner to that of tetrahydroberberine (THB). Both compounds enhanced barbiturate-induced hypnosis. They did not have an anticonvulsant effect on convulsive seizures induced by bicuculline, pentetrazole or strychnine. THB and THB-CS blocked dopamine-stimulated adenylate cyclase activity. These compounds showed almost equipotent affinities to dopamine D1 (3H-SCH-23390) and D2 (3H-spiperone) receptors but did not have significant affinity to mu-opioid, muscarinic and alpha 2-adrenergic receptors, and benzodiazepine binding sites. Furthermore, both compounds did not elicit cataleptogenic behavior, even at very high doses. These data suggest that THB and THB-CS have a central depressant effect through both D1 and D2 dopaminergic receptors and may have different modes of action from that of standard neuroleptics.
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PMID:Dopaminergic unique affinity of tetrahydroberberine and l-tetrahydroberberine-d-camphor sulfonate. 183 15

Preincubation of rat forebrain membranes for 30-60 min with micromolar concentrations of the pineal hormone, melatonin, significantly inhibited forskolin-stimulated adenylate cyclase (AC) activity. Melatonin had an EC25 (concentration which inhibited AC activity by 25%) of 600 microM and caused a maximal inhibitory effect of approximately 30% at a concentration of 1000 microM. A comparison of the effects of melatonin and its analogs, 6-chloromelatonin and 2-iodomelatonin, in the striatum revealed that these halogenated drugs were 2-3 times more potent than melatonin in inhibiting AC activity. The EC25 values were 611, 226 and 189 microM for melatonin, 6-chloromelatonin and 2-iodomelatonin respectively. The receptor antagonists phentolamine (alpha-adrenergic), propranolol (beta-adrenergic), and metergoline (serotonergic) did not block the effect of melatonin in forebrain membranes. The central-type benzodiazepine (BZ) antagonist, Ro 15-1788 (flumazenil), also failed to block the inhibitory effects of melatonin, and the benzodiazepines, diazepam and Ro 5-4864, on AC activity. Evidence that inhibition of adenylate cyclase activity may be involved in the prevention of seizures suggests that the reported anticonvulsant effect of large doses of melatonin may be due to this mechanism. The greater potency of the halogenated melatonin analogs in inhibiting AC suggests that further study of their potential usefulness as anticonvulsants would be worthwhile.
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PMID:Pharmacological inhibition of forskolin-stimulated adenylate cyclase activity in rat brain by melatonin, its analogs, and diazepam. 226 Sep 93

A mouse model for pertussis immunization encephalopathy has been described with features that closely resemble the severe adverse reactions occasionally seen after pertussis vaccine administration,m including seizures and a shock-like state leading to death. These reactions are produced with nearly one hundred percent efficiency provided that the mice immunized with Bordetella pertussis have 1) the appropriate major histocompatibility (H-2) genotype, 2) have been sensitized to bovine serum albumin (BSA), and 3) that the injected B. pertussis contained sufficient amounts of pertussis toxin. Antibody titres were measured in mice with haplotypes H-2d.s.k. that are highly susceptible to encephalopathy as well as in H-2b mice, that are totally resistant. Mice with H-2d.s.k. haplotypes were high responders to BSA, while H-2b (B10) mice were non-responders to BSA. Both H-2d and H-2b mice responded well to B. pertussis. Encephalopathy was induced in resistant H-2b mice with B. pertussis and passively administered anti-BSA antiserum, but not with B. pertussis and anti-(T,G)-A--L antibody. This indicated that B. pertussis and anti-BSA were absolutely required for development of encephalopathy. Encephalopathy could be induced in mice decomplemented with cobra venom factor and given BSA and B. pertussis. Several single-site mutants of B. pertussis affecting single virulence factors were induced with transposon Tn5. One of these mutants, BP357, deficient in pertussis toxin production, had a greatly reduced encephalopathic potential in the mouse model compared to the virulent strain BP 338, or to BP348, an adenylate cyclase and hemolysin double mutant, or to BP 349, a hemolysin mutant.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Murine model for pertussis vaccine encephalopathy: role of the major histocompatibility complex; antibody to albumin and to Bordetella pertussis and pertussis toxin. 287 26

The effect of a single electroconvulsive shock (ECS) (30 min and 24 h after treatment) and repeated ECS (10 once-daily) on the adenosine neuromodulatory system was investigated in rat cerebral cortex, cerebellum, hippocampus, and striatum. The present study examined the adenosine A1 receptor using N6-[3H]cyclohexyladenosine ([3H]CHA), the A2 receptor using 5'-N-[3H]ethylcarboxyamidoadenosine ([ 3H]NECA), adenylate cyclase using [3H]forskolin, and the adenosine uptake site using [3H]nitrobenzylthioinosine ([3H]NBI). At 30 min after a single ECS, the Bmax of the [3H]NBI binding in striatum was increased by 20%, which is in good agreement with the well-known postictal adenosine release. The Bmax of [3H]forskolin binding in striatum and cerebellum was increased by 60 and 20%, respectively. In contrast to earlier reported changes following chemically induced seizures, [3H]CHA binding was not altered postictally. At 24 h after a single ECS, there were no changes for any ligand in any brain region. Following repeated ECS, there was a 20% increase of [3H]CHA binding sites in cerebral cortex, which lasted for at least 14 days after the last ECS. [3H]Forskolin binding in hippocampus and striatum was 20% lowered 24 h after 10 once-daily ECS but had already returned to control levels 48 h after the last treatment. Evidence is provided that the upregulated adenosine A1 receptors are coupled to guanine nucleotide binding proteins and, furthermore, that this upregulation is not paralleled by an increase in adenylate cyclase activity as labeled by [3H]forskolin.
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PMID:Electroconvulsive shock (ECS) and the adenosine neuromodulatory system: effect of single and repeated ECS on the adenosine A1 and A2 receptors, adenylate cyclase, and the adenosine uptake site. 291 Oct 34

Carbamazepine (CBZ)-induced water intoxication occasionally limits its usefulness in refractory seizures and trigeminal neuralgia. Fluid restriction, CBZ dose reduction, or concomitant phenytoin therapy may be impractical or ineffective. Demeclocycline (7-chloro-6 demethyl tetracycline) (DMC) corrected the CBZ-induced water intoxication in a 51-year-old man with refractory complex partial seizures and a normal antidiuretic hormone (ADH) level. DMC inhibits ADH-sensitive adenylate cyclase activity in the renal collecting duct and may be useful in correcting the ADH-like or renal antidiuretic effect of CBZ.
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PMID:Perspective on carbamazepine-induced water intoxication: reversal by demeclocycline. 309 19

The onset of therapeutic effectiveness of carbamazepine is generally very rapid in the treatment of seizure and paroxysmal pain disorders, shows some lag in the treatment of mania, and exhibits the longest lag in depression. These time course variations may indicate that different mechanisms underlie the efficacy of carbamazepine in the differential neuropsychiatric syndromes. Biochemical and pharmacological data suggest that the anticonvulsant effects of carbamazepine are related to "peripheral-type" benzodiazepine and alpha 2-noradrenergic receptor systems and to its ability to stabilize sodium channels. GABAB (baclofen-like) actions appear to be involved in antinociceptive, but not anticonvulsant, effects. The relatively acute time course of antimanic efficacy may be related to the above-mentioned mechanisms or to other effects related to systems postulated to be altered in the manic syndrome. These effects might include carbamazepine's ability to increase acetylcholine in the striatum, decrease probenecid-induced levels of CSF homovanillic acid (HVA) in man and dopamine turnover in animals, decrease CSF norepinephrine in manic patients, inhibit adenylate cyclase activity (in response to norepinephrine, dopamine, adenosine, or ouabain), decrease GABA turnover, or act as a vasopressin agonist. Efficacy in depression may be related to actions in man that take time or chronic drug administration to develop, such as increases in plasma tryptophan, decreases in CSF somatostatin, decreases in thyroid indices, and increases in urinary free cortisol excretion and, in animals, increases in substance P sensitivity and increases in brain adenosine receptors. The ability of carbamazepine to block the development of lidocaine- and cocaine-induced seizures also requires chronic administration, suggesting that these seizure models may provide a unique perspective for understanding mechanisms of time-dependent effects.
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PMID:Time course of clinical effects of carbamazepine: implications for mechanisms of action. 328 May 60

The effect of the ganglioside GM1 on amplitude of the electroencephalogram, neurologic function, and histology has been studied in chronic middle cerebral artery occlusion in cats. Ischemia was produced by a 2-hour occlusion of the left middle cerebral artery and was followed by a 7-day observation period. GM1 was intravenously administered 30 minutes after occlusion and daily during the observation period. Using the reduction in the electroencephalogram amplitude to measure stroke severity, three cats with mild, three cats with moderate, and three cats with severe stroke were treated with 5 mg/kg GM1. Nine cats, three in each group, were treated with 30 mg/kg GM1, while nine cats, three in each group, received middle cerebral artery occlusion but no treatment. In all cats there was a precipitous fall in mean electroencephalogram amplitude during occlusion, followed by a secondary fall during the observation period. Treated cats showed better recovery of electroencephalogram amplitude during the first 4 hours of reperfusion and a smaller secondary fall than untreated cats. Treated cats, especially those treated with 5 mg/kg GM1, showed significant recovery of neurologic deficits compared with untreated cats. Histologic damage was less in treated cats than in untreated cats. Some cats treated with 30 mg/kg GM1 exhibited convulsions, whereas no untreated cat showed any seizure activity. Our findings suggest that gangliosides may improve the recovery of both neurologic deficits and morphologic damage in the central nervous system. These positive effects might be tentatively explained by stimulation of enzymatic activities such as Na+, K+-ATPase and adenyl cyclase.
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PMID:Effect of the ganglioside GM1 on neurologic function, electroencephalogram amplitude, and histology in chronic middle cerebral artery occlusion in cats. 340 Jan 1


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