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

Previous research has shown that ethosuximide in high enough doses disrupts operant responding in pigeons. Whether or not these same doses protect against seizure activity in this species has not been determined. In the present study a system for scoring pentylenetetrazol-induced seizures in pigeons was developed and the effects of ethosuximide on such seizures were evaluated. Pentylenetetrazol at 15, 27 and 47 mg/kg reliably induced seizures in Experiment 1. In Experiment 2 six doses of ethosuximide were tested for their seizure-controlling effectiveness. Doses of 20, 40, 80, 160 and 320 mg/kg ethosuximide had little effect on seizures induced by 27 mg/kg pentylenetetrazol; 640 mg/kg significantly reduced but did not completely eliminate seizures. This dose (640 mg/kg) is several times higher than the doses found to disrupt operant behavior in our previous studies.
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PMID:Pentylenetetrazol-induced seizures in pigeons and the effects of ethosuximide thereon. 278 Jul 69

Pentylenetetrazol (PTZ, 45 mg/kg, ip) impaired retention of a one-trial step-through inhibitory avoidance task when injected into male Swiss mice 10 min after training, as indicated by retention performance 48 h later. The amnestic effect of PTZ was prevented by naltrexone (0.01 or 0.10 mg/kg, ip) administered after training, but prior to PTZ-treatment. On the contrary, neither naltrexone methyl bromide (0.01, 0.10, or 10.0 mg/kg, ip), a quaternarium analog of naltrexone, nor MR2266 (0.01 or 0.10 mg/kg, ip), a putative kappa opiate receptor antagonist, modified the behavioral effects of PTZ. On the other hand, the body seizures produced by PTZ were unaffected by any of the three opiate receptor antagonists that were given before the convulsant. Taken together, these results suggest that the effects of PTZ on retention are mediated, at least in part, by opioid peptides of central origin, and rules out a possible participation of opioid peptides derived from prodynorphin-precursor molecule. Administration of beta-endorphin (0.01 or 0.10 microgram/kg, ip) 10 min prior to testing attenuate the retrograde amnesia caused by PTZ. The effect of beta-endorphin was prevented by the simultaneous administration of naltrexone (0.10 mg/kg, ip) prior to testing. Naltrexone has no effect of its own upon retrieval. These results suggest that the impairment of retention induced by PTZ is probably due, at least in part, to a release of opioid peptides in the brain during the post-training period. PTZ given after training do not affect consolidation or memory storage, as mice thus treated may retrieve the learned information when they are submitted to an appropriate neurohumoral and/or hormonal state in the test session, that is, beta-endorphin injection. Therefore, the action of PTZ would be primarily at the level of the mechanism that make stored information available for late retrieval.
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PMID:The impairment of retention induced by pentylenetetrazol in mice may be mediated by a release of opioid peptides in the brain. 282 89

In dogs, the influence of morphine (1 mg/kg i.m.), fentanyl (10 and 30 micrograms/kg i.v.), meperidine (6 mg/kg i.m.), and pentazocine (3 mg/kg i.m.) on the pentetrazole seizure threshold was studied. Pentetrazole was infused i.v. at a rate of 10 mg/kg per min up to the first generalized myoclonic jerk. The analgesic treatments lowered the seizure threshold considerably in 5 out of 6 dogs, and fentanyl and pentazocine led to an increased incidence of clonic-tonic seizures after the end of the pentetrazole infusion.
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PMID:Morphine-like analgesics and convulsive threshold for pentetrazole in dogs. 287 18

Cerebellar stimulation has been associated with anticonvulsant activity in several experimental seizure models. We examined the effect of destruction of cerebellar climbing fibers, by systemic administration of 3-acetylpyridine (3AP) or electrothermic lesion of the inferior olive, on seizures produced by various chemical convulsants in rats. We found that inferior olive lesioned rats had lower threshold to seizures induced by strychnine and brucine, both glycine antagonists. The dose response curve for strychnine seizure was shifted 2.5 times to the left in 3AP lesioned rats. No difference in seizure threshold was seen when picrotoxin, bicuculline or pentylenetetrazole PTZ) were used to produce seizures. Abnormal motor behavior (AMB) including myoclonus, backward movement and hyperextension, produced by all of the convulsants tested, was significantly aggravated in 3AP pretreated rats. The inferior olive-climbing fiber projection to the cerebellum appears to modulate seizures induced by inhibition of glycinergic neurotransmission.
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PMID:Effect of inferior olive lesion on seizure threshold in the rat. 288 46

The ability of isoproterenol to induce symptoms and laboratory findings of a vasodepressor reaction was tested in 48 patients, ages 17 to 74, divided into 4 groups according to the reason for their referral. Group 1 comprised 12 patients with vasodepressor syncope, group 2 had 8 patients with syncope of unknown origin, group 3 included 11 patients with syncope due to seizures in 2 and ventricular tachycardia in 9, group 4 had 17 patients with various arrhythmias not associated with syncope. Isoproterenol boluses were administered starting at 2 micrograms and increased in 2-micrograms steps to a maximum of 8 micrograms at 0 degree and +60 degrees. The responses at 0 degrees were all normal. At +60 degrees a vasodepressor reaction consisting of syncope or near syncope, hypotension and bradycardia was produced by isoproterenol (mean dose 6.0 +/- 0.26 micrograms) in 8 patients from group 1 (66.6%), 4 from group 2 (50%), 0 from group 3 and 4 from group 4 (23.5%). Three of the 4 patients in group 4 had a remote history of classic vasodepressor syncope. The overall sensitivity and specificity of the test were 73 and 85%, respectively, while the predictive accuracy of a test with positive or negative outcome were 69 and 89%, respectively. Muscarinic receptor blockade with atropine in 4 patients prevented isoproterenol-induced bradycardia but not hypotension or symptoms of fainting. Beta-adrenergic receptor blockade with propranolol inhibited all aspects of the isoproterenol-induced faint. Thus, the administration of isoproterenol during a passive upright tilt may identify persons who suffer from or are prone to a vasodepressor reaction.
Am J Cardiol 1989 Jan 01
PMID:Isoproterenol induction of vasodepressor-type reaction in vasodepressor-prone persons. 290 60

Electrically- and chemically-induced convulsions, as well as spontaneous convulsions, triggered off a large increase in brain PG synthesis occurring mainly in cerebral cortex and hippocampus. Prevention of PG synthesis by cyclooxygenase inhibitors had no influence on the onset of the first clonic seizure, but markedly reduced the latency time of the final tonic seizure. Accordingly, also the acute toxicity of the convulsant PTZ was enhanced after cyclooxygenase inhibition by various NSAIDs (decrease in LD50). On the other hand, if brain concentrations of prostanoids were increased by a preceding ECS treatment, the onset of PTZ-induced clonic seizures was markedly delayed, and the acute toxicity of the convulsant was reduced. Both effects were abolished after inhibition of PG synthesis. The major cerebral PG formed during convulsions (PGD2) proved to have anticonvulsive properties when injected i.c.v. Also, in convulsion-prone gerbils, anticonvulsive effects of cerebral PGs were observed. These results suggest that endogenously formed brain PGs possess anticonvulsive properties of biological relevance.
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PMID:Formation and functions of prostaglandins in the central nervous system in rodents. 293 71

Influence of ethosuximide (ESI, 125 mg/kg i.p.) and dipropylacetate (DPA, 300 mg/kg i.p.) pretreatment on electrocorticographic changes induced by pentamethylenetetrazole (PTZ, 20 mg/kg dose every 5 min) was studied in rats aged 7, 12, 18 and 90 days. PTZ alone induced isolated spikes and/or sharp waves as the first sign of its action in all age groups except in adult animals where rhythmic theta activity was elicited. The antiepileptic effect of DPA was observed in 12- and 18-day-old rats, ESI specifically inhibited rhythmic activity in adult rats. ECoG seizures induced by high doses of PTZ were inhibited by DPA in all age groups, ESI tended to be effective in adult rats only. DPA did not change the pattern of ECoG seizures, whereas ESI led to replacement of the spike-and-wave rhythm by serrated waves in adult animals. The low ability of immature brain to generalize ictal activity was further diminished by ESI.
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PMID:Influence of ethosuximide and dipropylacetate on metrazol-induced electrocorticographic changes during ontogenesis in rats. 294 8

Influence of propranolol (5 mg/kg i.p.) on rhythmic metrazol activity (RMA) was studied in 11 male albino rats with chronically implanted cortical as well as subcortical (thalamic ventrobasal complex and dorsal hippocampus) electrodes. Metrazol was injected subcutaneously at a low dose of 30 mg/kg. Another group of five rats was used to study the action of propranolol on spontaneously appearing episodes of rhythmic spikes as well as on vigilance. The incidence of both rhythmic metrazol activity and episodes was significantly increased by propranolol. The latency to the first burst of rhythmic metrazol activity and to the maximum of its incidence was significantly shortened by propranolol. Propranolol also increased the incidence of relaxed wakefulness and delayed the appearance of slow wave sleep. The facilitation of RMA and spontaneous episodes could not be explained only by the increased amount of relaxed wakefulness, i.e. the vigilance level necessary for these two phenomena, because these changes did not coincide in time. In two animals, the combination of propranolol and metrazol led to the appearance of ictal activity which was sometimes accompanied by partial clonic convulsions. This phenomenon was never seen after metrazol alone (30 mg/kg s.c.) in control recordings. Propranolol was found to potentiate the possible models of human absences--spontaneous episodes, RMA and minimal clonic seizures.
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PMID:Influence of propranolol on rhythmic electrocorticographic activity induced by metrazol in rats. 294 49

The convulsant influence of high doses of diazepam, in the presence of the benzodiazepine receptor antagonist Ro 15-1788, was studied in rats. Animals were implanted with permanent cortical screw electrodes for EEG recording. EEG spiking and accompanying clonic activity was observed in rats receiving greater than or equal to 200 mg/kg diazepam, followed 10 minutes later by Ro 15-1788 (20 mg/kg). Pentylenetetrazole and picrotoxin seizure thresholds, measured during constant rate iv infusion, were significantly lowered by pretreatment with diazepam (250 mg/kg) and Ro 15-1788 (20 mg/kg) administered 30 and 20 minutes, respectively, before seizure threshold measurement. It is proposed that this convulsive activity of diazepam is mediated through the picrotoxinin receptor.
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PMID:Convulsant component of a depressant benzodiazepine. 299 72

Felbamate (2-phenyl-1,3-propanediol dicarbamate), phenytoin, phenobarbital, ethosuximide, and valproate were evaluated in mice and rats with a battery of well-standardized anticonvulsant test procedures. The results obtained indicate that felbamate exhibits a wider range of experimental anticonvulsant activity than either phenytoin or ethosuximide and a somewhat more restricted range than either phenobarbital or valproate. Felbamate is effective in nontoxic intraperitoneal doses in mice by the maximal electroshock seizure (MES), pentylenetetrazol (s.c. PTZ), and picrotoxin (s.c. Pic) tests but ineffective against bicuculline- and strychnine-induced seizures; it is effective after nontoxic oral doses in both mice and rats by the MES and s.c. PTZ tests. When compared on the basis of protective indices (PI = TD50/ED50) calculated from the intraperitoneal data in mice, the PIs for felbamate were from 1.05 to 2.37 times higher than those of the prototype antiepileptics. Overall, except for the s.c. PTZ test in mice and rats after oral administration, the PIs were equal to or higher than those of the prototype agents. The PIs for the s.c. PTZ test in mice and rats after oral administration were within the range of the prototype agents. These data indicate that felbamate is a relatively nontoxic agent with a unique profile of anticonvulsant action.
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PMID:Comparative anticonvulsant activity and neurotoxicity of felbamate and four prototype antiepileptic drugs in mice and rats. 300 30


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