Navegando por Palavras-chave "SEIZURE"

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    AGE DEPENDENCY of the SUSCEPTIBILITY of RATS TO AMINOOXYACETIC ACID SEIZURES
    (Elsevier B.V., 1992-06-19) Turski, W.; Dziki, M.; Parada, J.; Kleinrok, Z.; Cavalheiro, E. A.; Universidade Federal de São Paulo (UNIFESP)
    Immature rats are more susceptible to clonic seizures induced by aminooxyacetic acid (AOAA) than mature and senile rats. Highest susceptibility to AOAA seizures was observed in 7-14-day-old rat pups. the lowest susceptibility was recorded in 10-20 month-old rats. AOAA seizures in 14-day-old rats were blocked by clonazepam and valproate, but not by phenobarbital, carbamazepine, diphenylhydantoin, trimethadione or ethosuximide. Morphological analysis of brains from 14-day- and 3-month-old rats which experienced AOAA seizures did not reveal epilepsy-related damage. These observations suggest that immature rat brain is highly prone to convulsions induced by AOAA and that such convulsions are difficult to control by available antiepileptic treatment.
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    AGE-RELATED ANTICONVULSANT ACTIVITY of NMDA in the RAT CAUDATE-PUTAMEN
    (Elsevier B.V., 1992-06-19) Cavalheiro, E. A.; Defeo, M. R.; Mecarelli, O.; Ricci, G.; UNIV LA SAPIENZA; Universidade Federal de São Paulo (UNIFESP)
    Striatal pathways are important for modulating the threshold for seizures in the rat forebrain. N-Methyl-D-aspartate (NMDA), an excitatory amino acid derivative and powerful anticonvulsant agent, when injected into the brain, has been shown to protect adult rats against kindling and pilocarpine-induced seizures when injected into the caudate-putamen. the present study examines whether the anticonvulsant action of NMDA in the caudate-putamen varies with age. Bilateral striatal administration of NMDA was effective in suppressing bicuculline-induced seizures in rats older than 23 days of age. the results suggest that striatal pathways involved in the anticonvulsant activity of NMDA in the caudate-putamen are not functionally active in developing rats before the 4th week of life.
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    DECREASED SUSCEPTIBILITY TO SEIZURES INDUCED BY BICUCULLINE AFTER TRANSIENT BILATERAL CLAMPING of the CAROTID ARTERIES in RATS
    (Springer, 1991-01-01) Sieklucka, M.; Bortolotto, Z.; Heim, C.; Block, F.; Sontag, K. H.; UNIV GOTTINGEN; MAX PLANCK INST EXPTL MED; INST CLIN PATHOL; Universidade Federal de São Paulo (UNIFESP)
    Rats were exposed for 24 min to bilateral clamping of the common carotid arteries (BCCA) in pentobarbital anaesthesia. 14 days later the animals were subjected to subcutaneous injection of (+)-bicuculline (3 or 4 mg/kg). A significantly decreased susceptibility to bicuculline-induced seizures could be observed in BCCA treated rats compared with sham operated controls. It is suggested that BCCA treatment protects animals against status epilepticus and lethal toxicity produced by bicuculline. Electrographic recordings of the BCCA animals revealed no ictal activity within 1 h after bicuculline injection. An analysis of the GABA content showed a significant increase in the hippocampus (HPC), frontal cortex (FCX), parietal cortex and substantia nigra in BCCA animals compared with controls. It is therefore possible that an increase in GABA content postsynaptically counteracts the GABA(A) antagonistic effect of bicuculline in BCCA animals thus preventing the normal seizure inducing effect of this substance.
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    PARADOXICAL ANTICONVULSANT ACTIVITY of the GAMMA-AMINOBUTYRATE ANTAGONIST BICUCULLINE METHIODIDE in the RAT STRIATUM
    (Wiley-Blackwell, 1991-01-01) Turski, L.; Diedrichs, S.; Klockgether, T.; Schwarz, M.; Turski, W. A.; Sontag, K. H.; Bortolotto, Z. A.; Calderazzofilho, L. S.; Cavalheiro, E. A.; MAX PLANCK INST EXPTL MED; Universidade Federal de São Paulo (UNIFESP)
    Bicuculline methiodide (BMI), a gamma-aminobutyrate (GABA) antagonist, is a powerful convulsant agent when injected into the cerebral ventricles, amygdala, hippocampus, thalamus, neocortex, and deep prepiriform cortex in rats. in contrast, bilateral microinjection of BMI into the rat striatum confers protection against seizures induced by the cholinergic agonist pilocarpine (380 mg/kg, i.p.), with an ED50 of 94 fmol (range 45-195 fmol). No topographical variation in the anticonvulsant action of BMI was detected throughout rostrocaudal and dorsoventral aspects of the striatum. the anticonvulsant action of BMI in the striatum was reversed by coadministration of the GABA agonist muscimol or by blocking GABA-mediated inhibition in either the substantia nigra pars reticulata or in the entopeduncular nucleus. the results show that blockade of GABA-mediated inhibition in the striatum has a powerful anticonvulsant effect in the pilocarpine model, suggesting that GABAergic transmission in the striatum modulates the seizure propagation in the forebrain.
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    TRANSIENT OCCLUSION of RAT CAROTID ARTERIES DECREASES SUSCEPTIBILITY TO PILOCARPINE SEIZURES
    (Elsevier B.V., 1991-03-29) Heim, C.; Bortolotto, Z. A.; Cavalheiro, E. A.; Sontag, K. H.; MAX PLANCK INST EXPTL MED; Universidade Federal de São Paulo (UNIFESP)
    Bilateral clamping of the carotid arteries (BCCA) for 24 min protects animals against convulsive effects of intraperitoneal injection of 300 mg/kg of pilocarpine when administered 14 days after surgery. Electrographic recordings from hippocampus, frontal cortex, striatum and substantia nigra demonstrate that (1) no spontaneous spiking activity is caused by the BCCA when observed for up to 10 days after surgery, (2) spiking activity can only be recorded in limbic structures but not in the frontal cortex after systemic administration of pilocarpine. These observations suggest that the propagation of seizure activity from subcortical limbic structures to the neocortex is affected by BCCA.