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PubMed1991

Modulators of N-methyl-D-aspartate protect against diazepam- or phenobarbital-resistant cocaine convulsions.

The anticonvulsants diazepam (1-10 mg/kg) and phenobarbital (30-100 mg/kg) protected against lethality without altering clonic convulsions induced by 75 mg/kg cocaine (CD100) in male Swiss Webster mice. In contrast, the non-competitive N-methyl-D-aspartate (NMDA) antagonists, MK-801 (dizocilpine) and phencyclidine, produced dose-dependent protection against cocaine convulsions. The competitive NMDA antagonists, CPP and NPC 12626, were also anti-convulsant, without producing the behavioral disturbances associated with non-competitive antagonists. Diazepam and phenobarbital protected against convulsions induced by 60 mg/kg cocaine (90% convulsions alone). Compounds that act at the strychnine-insensitive glycine receptor of the NMDA receptor complex, ACPC and 7-chlorokynurinic acid, also protected against convulsions induced by 60 mg/kg cocaine. In contrast, the non-opioid antitussive anticonvulsants (dextromethorphan, caramiphen, and carbetapentane) were not active against either dose of cocaine. The efficacy of compounds as antagonists of the convulsant effects of cocaine and NMDA appear related. These results suggest a potential role for the NMDA receptor complex in the convulsant actions of cocaine and new molecular targets for drug discovery in treating cocaine toxicity.

Amino Acids↗
PubMed1984

Experimental convulsions in rats induced by intraventricular administration of kynurenine and structurally related compounds.

Administration of L-kynurenine and some analogous molecules into the right lateral ventricle caused convulsive attacks in rats. These convulsions are tonic-clonic. Various modifications of the structure of L-kynurenine affected the production of convulsions. In particular, methylation of the carboxyl group increased the potency. Methylation of the carboxyl function and hydroxylation of the benzene ring greatly increased the latency and the duration of the convulsions. Removal of the carboxyl function or its reduction resulted in the loss of the epileptogenic effect. Masking of the amino function with formyl or acetyl residues also produced inactive compounds. The results of structural modification of the kynurenine carbon skeleton clearly show that the structure essential for stimulation of convulsive activity includes a free amino group and a free or masked carboxyl function. The molecular structure able to induce convulsive effects appears to be the laevo -isomer of kynurenine, since the dextro-form has been proved to be inactive. The convulsant activity, evaluated as the ED50, for L-kynurenine, is between that of bicuculline and pentamethylenetetrazole . The convulsant mechanism of kynurenine is unknown, but might very possibly involve interference with the activity of certain inhibitory neurotransmitters.

Animals↗
PubMed1994

Sensitivity of the circadian rhythm of kainic acid-induced convulsion susceptibility to manipulations of corticosterone levels and mineralocorticoid receptor binding.

Increases in corticosterone levels have been associated with enhanced susceptibility and decreases in corticosterone levels have been associated with decreased susceptibility to convulsions in mice. The proconvulsant effects of corticosterone are believed to be mediated by central mineralocorticoid receptors (MR). Both convulsion susceptibility and plasma corticosteroid levels display circadian rhythmicity. When corticosterone levels are at their lowest, hippocampal MR binding is submaximal, whereas when corticosterone levels are at their circadian peak, hippocampal MR binding is maximal. In the present experiments the relationship between circadian rhythms of susceptibility to kainic acid-induced convulsions and plasma corticosterone levels was investigated. In addition, the effects of exogenously administered corticosterone and the MR antagonist spironolactone were examined at times of different convulsion susceptibility. In general, lower plasma corticosterone levels were associated with decreased convulsion susceptibility and higher plasma corticosterone levels were associated with greater convulsion susceptibility. Corticosterone, administered when endogenous levels were low, had a proconvulsant effect. Spironolactone, administered when corticosterone levels were higher and hippocampal MR were presumably maximally occupied, had an anticonvulsant effect. These results indicate that the circadian rhythm in susceptibility to kainic acid-induced convulsions is sensitive to manipulations of corticosterone levels and MR binding. Degree of central MR occupancy may, in part, mediate convulsion susceptibility in humans as well as laboratory animals.

Animals↗
PubMed1986

Effects of new neuroleptics, isofloxythepin and zotepine, on post-decapitation convulsions and prolactin secretion in rats.

Oral administration of isofloxythepin (0.5-8.0 mg/kg) inhibited decapitation convulsions in a dose-dependent manner as shown by decreasing the incidence and shortening the convulsion's duration, the effects continuing until 24 hr after administration. Zotepine (8, 16 mg/kg, SC) also decreased the duration but not the incidence of the convulsion. However, the other neuroleptics such as haloperidol, spiperone, perphenazine, trifluoperazine, pimozide and sulpiride failed to affect decapitation convulsions. Reserpine (8 mg/kg, SC) inhibited decapitation convulsions, accompanied by decreasing levels of norepinephrine, dopamine and serotonin in the spinal cord. Isofloxythepin at doses of 4 and 8 mg/kg, PO which completely abolished decapitation convulsions, failed to change norepinephrine and dopamine levels but increased serotonin levels in the spinal cord. Isofloxythepin (0.5-8.0 mg/kg) increased serum prolactin levels in a dose-dependent manner and zotepine (16 mg/kg), haloperidol (1 mg/kg) and reserpine (8 mg/kg) also elevated the levels. The results imply that both isofloxythepin and zotepine, but not the other neuroleptics, inhibit convulsions without decreasing spinal levels of norepinephrine which appears to be the amine most directly involved in the occurrence of decapitation convulsions, although these neuroleptics enhance prolactin secretion by blocking dopamine receptors in the pituitary.

Animals↗
PubMed1991

Effects of cold-restraint and swim stress on convulsions induced by pentylenetetrazol and electroshock: influence of naloxone pretreatment.

The influence of two stressogenic conditions, restraint at 4 degrees C for 30 min (cold-restraint stress; CRS) or swimming at 20 degrees C for 3 min (swim stress; SS), on nociception and on convulsions triggered by different agents was assessed in mice. In saline-pretreated mice CRS and SS caused analgesia (hot-plate test, 56 degrees C), delayed the onset of convulsions induced by pentylenetetrazol (PTZ, 100 mg/kg, IP) and aggravated convulsions elicited by maximal transcorneal electroshock (150 mA pulses at 60 Hz for 0.2 s). Pretreatment with naloxone (10 mg/kg, SC, 30 min prior to testing), which did not affect the responsiveness of nonstressed mice to the hot plate or to the convulsant treatments, attenuated the development of analgesia following CRS, but not SS, and further prolonged the latency to onset of PTZ-induced convulsions in both stressed groups. Thus the extent to which CRS and SS can each delay the onset of PTZ-triggered convulsion appears to be limited by activation of a proconvulsant opioid system. In contrast, naloxone pretreatment did not modify the effects of CRS or SS on the severity of electroshock-induced seizures. In conclusion, CRS and SS can each, simultaneously, exert anticonvulsant and proconvulsant influences on responsiveness to PTZ and electroshock, respectively. Also, both forms of stress can activate an opioid system modulating the onset of PTZ-induced seizures, which is distinct from that controlling nociception. These findings, together with those of other stress, convulsions and opioid systems, which depends on the characteristics of the stressogenic condition, species, convulsant agent and parameter considered.

Analgesia↗
PubMed1993

N-methyl-D-aspartate receptors contribute to guanidinosuccinate-induced convulsions in mice.

Increased levels of the endogenous convulsant guanidinosuccinate (GSA) might contribute to the epileptic symptomatology presenting in patients with renal failure. Little is known, however, about the underlying epileptogenic mechanism of guanidinosuccinate-induced convulsions. In this paper, we present pharmacological evidence for a direct excitatory action of this compound. In particular, the close involvement of N-methyl-D-aspartate (NMDA) receptors in the pathogenesis of GSA-induced generalized convulsions is suggested. GSA potentiated NMDA-induced convulsions significantly, but not L-glutamate- or kainate-induced convulsions. Conversely, and in addition, NMDA receptor antagonists, like D(-)-2-amino-5-phosphonovalerate, CGP 37849 [DL)-(E)-2-amino-4-methyl-5-phosphono-3-pentenoate] or ketamine (but not kynurenate), blocked the convulsions induced by i.c.v. injection of GSA dose dependently whereas anti-epileptic drugs, like carbamazepine, diazepam, phenobarbital or valproate, only abolished the tonic extension phase of these convulsions. Thus, NMDA receptors appear to be involved, at least partly, in GSA-induced convulsions.

2-Amino-5-phosphonovalerate↗
PubMed2005

Magnesium and bupivacaine-induced convulsions in awake pregnant rats.

BACKGROUND: Magnesium sulfate (MgSO(4)) is widely used for the treatment and prevention of convulsions associated with preeclampsia. The aim of this study was to determine whether it alters the dose of bupivacaine required to produce convulsions in awake pregnant rats. METHOD: Twelve pregnant rats were pretreated with an intravenous infusion of either MgSO(4) or saline. Following 2 h of the pretreatment, bupivacaine was concomitantly infused in all animals until the onset of convulsions. Mean arterial pressure (MAP) and heart rate (HR) were monitored throughout. Serial arterial samples were obtained during the infusion. At the onset of convulsions, fetuses were delivered and maternal and fetal blood, as well as various tissue samples, were obtained. All samples were assayed for bupivacaine and magnesium concentrations. RESULTS: Maternal MAP and HR decreased significantly shortly after the initiation of MgSO(4), while saline did not affect these measurements. Baseline concentrations of magnesium in plasma were similar in both MgSO(4) and saline groups; magnesium increased significantly during the infusion of MgSO(4). The dose (mean+/-SD) of bupivacaine required to produce convulsions in the animals receiving MgSO(4) was significantly larger (10.2+/-1.9 mg/kg) than that in the saline group (5.9+/-1.0 mg/kg) (P<0.05). As a consequence, bupivacaine concentrations in the brain and liver at the onset of convulsions were greater in animals receiving MgSO(4) (16.0+/-8.4 and 18.2+/-4.3 microg/g wet weight, respectively) than in those given saline (12.1+/-2.2 and 9.9+/-2.0 microg/g wet weight, respectively). Fetal bupivacaine concentrations at the onset of convulsions in the MgSO(4) group were also higher than those in saline group. However, the rate of placental transfer of this drug was similar between MgSO(4) and saline animals. CONCLUSION: This study demonstrates that the clinically used concentration of magnesium sulfate increased the threshold of bupivacaine-induced convulsions in awake rats.

Anesthetics, Local↗
PubMed2006

Incidence, cause, and short-term outcome of convulsive status epilepticus in childhood: prospective population-based study.

BACKGROUND: Convulsive status epilepticus is the most common childhood medical neurological emergency, and is associated with significant morbidity and mortality. Most data for this disorder are from mainly adult populations and might not be relevant to childhood. Thus we undertook the North London Status Epilepticus in Childhood Surveillance Study (NLSTEPSS): a prospective, population-based study of convulsive status epilepticus in childhood, to obtain a uniquely paediatric perspective. METHODS: Clinical and demographic data for episodes of childhood convulsive status epilepticus that took place in north London were obtained through a clinical network that covered the target population. We obtained these data from anonymised copies of a standardised admission proforma; accident and emergency, nursing, ambulance, and intensive-care unit notes; and interviews with parents, medical, nursing, and paramedic staff. We investigated ascertainment using capture-recapture modelling. FINDINGS: Of 226 children enrolled, 176 had a first ever episode of convulsive status epilepticus. We estimated that ascertainment was between 62% and 84%. The ascertainment-adjusted incidence was between 17 and 23 episodes per 100,000 per year. 98 (56%, 95% CI 48-63) children were neurologically healthy before their first ever episode and 56 (57%, 47-66) of those children had a prolonged febrile seizure. 11 (12%, 6-18) of children with first ever febrile convulsive status epilepticus had acute bacterial meningitis. Conservative estimation of 1-year recurrence of convulsive status epilepticus was 16% (10-24%). Case fatality was 3% (2-7%). INTERPRETATION: Convulsive status epilepticus in childhood is more common, has a different range of causes, and a lower risk of death than that in adults. These paediatric data will help inform management of convulsive status epilepticus and appropriate allocation of resources to reduce the effects of this disorder in childhood.

Adolescent↗
PubMed1998

Cerebellar circuitry is activated during convulsive episodes in the tottering (tg/tg) mutant mouse.

Tottering (tg) is an autosomal recessive mutation of the calcium channel alpha1A subunit in the mouse that results in epileptic spike and wave discharges, mild ataxia and paroxysmal episodes of involuntary spasms of the limbs, trunk and face. These convulsions have been especially difficult to characterize because of their unpredictable occurrence and lack of electroencephalographic correlates. However, it is, in fact, possible to induce these convulsions, making this facet of the tottering phenotype amenable to controlled experimentation for the first time. Here, the neuroanatomical basis of the convulsions in tottering mice has been identified using in situ hybridization for c-fos messenger RNA to chart abnormal neuronal activity. Convulsion-induced c-fos messenger RNA expression was most prominent in the cerebellum of convulsing tottering mice. Additionally, cerebral cortex and principal cerebellar relay nuclei were also activated during a convulsion. The c-fos activation in the cerebellum temporally preceded expression in cerebral cortex, suggesting that cerebral cortex is not driving the expression of convulsions. These results suggest that the cerebellum, a region not classically associated with paroxysmal events, is important in the generation and/or maintenance of the intermittent convulsions in tottering mutant mice.

Animals↗
PubMed2000

Unprovoked seizures after complex febrile convulsions.

Children with complex febrile convulsions bear a higher risk of developing epilepsy than children with simple febrile convulsions. Complex febrile convulsions are defined by the presence of prolonged seizures, partial seizures and multiple seizures occurring during the same day. The aim of this study is to delineate the relative significance of each of the three criteria defining complex febrile convulsions. Fifty-seven out of 477 children (12%) admitted for febrile convulsions had complex febrile convulsions and normal neurological examination. Follow-up was available for 48 (84%) of them. Thirteen of these 48 (27%) had epilepsy at follow-up. The mean age of seizure onset among the patients with subsequent afebrile seizures was significantly lower than the rest (10.8 months versus 16.8 months). The patients with partial febrile convulsions showed a trend toward a higher risk (45%) of developing epilepsy than the patients with multiple febrile convulsions (21%).

Child↗
PubMed1999

Scopolamine-induced convulsions in food given fasted mice: effects of clonidine and tizanidine.

We recently reported that scopolamine pretreated mice fasted for 48 h developed clonic convulsions soon after they were allowed to eat ad libidum. Pretreatment with MK-801, the non-competitive NMDA antagonist, decreased the incidence of these convulsions. We suggested that a possible scopolamine-induced glutamatergic hyperactivity could account for these convulsions. Using alpha2-agonists, clonidine, which has been shown to inhibit glutamate release, and tizanidine, the present study was performed to find some additional data for the role of glutamate in the underlying mechanism of scopolamine-induced convulsions in food given fasted mice. Animals fasted for 48 h and pretreated (i.p.) with saline, clonidine (0.05, 0.10, 1 mg/kg) or tizanidine (0.10, 0.15, 0.30, 0.45 mg/kg) were treated (i.p.) with either saline or scopolamine (3 mg/kg). Then 20 min later, they were allowed to eat ad libidum and were observed for 30 min for the incidence and onset of clonic convulsions. All doses of clonidine pretreatment completely suppressed (0%) scopolamine-induced clonic convulsions (75%). On the other hand, only 0.15 mg/kg tizanidine pretreatment significantly decreased (15%) the incidence of convulsions; however as well as 0.15 mg/kg, both 0.30 and 0.45 mg/kg tizanidine pretreatments significantly increased latency to the onset of convulsions.

Animals↗
PubMedDate not supplied

Bupivacaine-induced convulsion is suppressed by MK-801.

BACKGROUND AND OBJECTIVES: Not only the facilitation of inhibitory synapses but also the suppression of excitatory synapses may be effective in treating convulsion induced by local anesthetics. The effects of MK-801, a N-methyl-D-aspartate (NMDA) receptor antagonist, on bupivacaine-induced convulsion and hemodynamic changes were studied. METHODS: Cortex and hippocampal (A4; L5.5; H8) electroencephalogram (EEG), heart rate, and mean arterial pressure were measured in 21 cats anesthetized with urethane. Blood samples were obtained when cats demonstrated arrhythmias, convulsed, and became hypotensive. In the control group (n = 7), bupivacaine was continuously infused until a hypotensive state of 40 mm/Hg was reached. In the MK-801 pretreated group (n = 7), MK-801 (0.5 mg/kg) was injected intravenously 15 minutes before the bupivacaine injection. In the MK-801 treatment group (n = 7), MK-801 (0.5 mg/kg) was injected intravenously at the appearance of convulsive EEG after the bupivacaine injection. RESULTS: Bupivacaine produced convulsion in the control group (17.1 +/- 2.4 microg/mL), but not in the MK-801 pretreated group. In the treatment group, convulsive EEG was suppressed gradually after injection of MK-801. The mean plasma bupivacaine concentrations (microg/mL) reaching arrhythmia and hypotension were 9.5 +/- 2.9 and 23.0 +/- 3.0, respectively, in the control group; 10.9 +/- 3.5 and 22.5 +/- 4.9, respectively, in the MK-801 pretreated group; and 7.5 +/- 1.6 and 21.0 +/- 3.0, respectively, in the MK-801 treatment groups. The mean arterial pressure and heart rate did not differ among the three groups. CONCLUSIONS: These results demonstrated that one mechanism of bupivacaine-induced convulsion is the excitatory neurotransmitter system in central nervous system and that MK-801 is effective in suppressing the convulsion without any effects on hemodynamics.

Anesthetics, Local↗
PubMed1999

Children presenting with convulsions (including status epilepticus) to a paediatric accident and emergency department: an audit of a treatment protocol.

All children who presented in a convulsion, including convulsive status epilepticus, to the accident and emergency department over a 12-month period and who required treatment, were reviewed retrospectively to identify the effectiveness and safety of a specific treatment protocol. This protocol recommends the initial use of one, or if necessary, two doses of rectal or intravenous diazepam (0.4 mg/kg) followed by the simultaneous administration of phenytoin (18 mg/kg) and rectal paraldehyde (0.4 mL/kg), with instructions for maximum doses and timings of administration. Eighty-one evaluable children (52 male) were audited. The mean age of the study population was 4.1 (range 0.1 to 14.9) years. Overall, the presenting convulsion was successfully terminated in 76 children (94%) within the accident and emergency department. In 69 children (85% of the entire study population) this was after a single dose of diazepam (rectal in 41 and intravenous in 28). In only an additional two children did the presenting convulsion stop after a second dose of diazepam. In five of the 10 children (50%) who received paraldehyde and phenytoin as a combination, the convulsion stopped. Nine patients (11%) required admission to the intensive-care unit, five because of persisting convulsive activity, and four because of respiratory depression. The results of this retrospective audit suggest that the current treatment protocol appears to be effective and relatively safe in treating acute convulsions, including convulsive status epilepticus. The audit is to be repeated prospectively to either confirm or refute these findings before recommending any changes to the protocol.

Adolescent↗
PubMed2002

Pharmacokinetics and anticonvulsant effects of diazepam in children with severe falciparum malaria and convulsions.

AIMS: Convulsions are a common complication of severe malaria in children and are associated with poor outcome. Diazepam is used to terminate convulsions but its pharmacokinetics and pharmacodynamics have not been studied in this group. Accordingly, we carried out a comparative study of the pharmacokinetics of intravenous (i.v.) and rectal (p.r.) diazepam. METHODS: Twenty-five children with severe malaria and a convulsion lasting >5 min were studied. Sixteen children received diazepam intravenously (i.v.; 0.3 mg kg(-1)) and nine rectally (p.r.; 0.5 mg kg(-1)). Plasma diazepam concentrations were measured by reversed phase high-performance liquid chromatography. The duration of convulsions, depth of coma, respiratory and cardiovascular parameters were monitored. RESULTS: Median maximum plasma diazepam concentrations of 634 (range 402-1507) ng ml(-1) and 423 (range 112-1953) ng ml(-1) were achieved at 5 and 25 min following i.v. and p.r. administration, respectively. All patients except three (one i.v. and two p.r.) achieved plasma diazepam concentration >200 ng ml(-1) within 5 min. Following p.r. administration, plasma diazepam concentrations were more variable than i.v. administration. A single dose of i.v. diazepam terminated convulsions in all children but in only 6/9 after p.r. administration. However, nine children treated with i.v. and all those treated with p.r. diazepam had a recurrence of convulsions occurring at median plasma diazepam concentrations of 157 (range: 67-169) and 172 (range: 74-393) ng ml(-1) , respectively. All the children in the i.v. and four in the PR diazepam group who had recurrence of convulsions required treatment. None of the children developed respiratory depression or hypotension. CONCLUSIONS: Administration of diazepam i.v. or p.r. resulted in achievement of therapeutic concentrations of diazepam rapidly, without significant cardio-respiratory adverse effects. However, following p.r. administration, diazepam did not terminate all convulsions and plasma drug concentrations were more variable.

Administration, Rectal↗
PubMed1995

Effect of vasoconstrictive agents added to lidocaine on intravenous lidocaine-induced convulsions in rats.

BACKGROUND: Epinephrine is reported to decrease the threshold of intravenous lidocaine-induced convulsions. However, the mechanism underlying this effect is not clear. Therefore, we carried out a study to examine the role of vasopressor-induced hypertension. METHODS: Fifty-six awake Wistar rats were assigned to seven groups of eight. All groups received a continuous intravenous infusion of lidocaine at a rate of 4 mg.kg-1.min-1 until generalized convulsions occurred. The control group (group C) received plain lidocaine. The acute hypertensive groups received lidocaine with epinephrine (group E), norepinephrine (group N), or phenylephrine (group P) to increase mean arterial blood pressure (MAP) to 150 +/- 5 mmHg. Sodium nitroprusside (SNP) was added to prevent an increase in mean arterial pressure in the remaining three groups (vasopressor-SNP groups). RESULTS: The acute hypertensive groups required significantly smaller cumulative doses of lidocaine to produce convulsions compared with control (C = 41.5 +/- 2.9 > E = 24.1 +/- 2.7, N = 27.1 +/- 2.8, P = 26.7 +/- 2.5 mg.kg-1; values are mean +/- SD, P < 0.01). In addition, plasma lidocaine concentrations (C = 11.0 +/- 0.7 > E = 7.4 +/- 0.5, N = 7.9 +/- 0.6, P = 8.1 +/- 0.8 micrograms.ml-1, P < 0.01) and brain lidocaine concentrations (C = 50.9 +/- 4.5 > E = 32.6 +/- 4.2, N = 34.5 +/- 4.8, P = 37.1 +/- 4.5 micrograms.g-1, P < 0.01) were less in the acute hypertensive groups at the onset of convulsions. In the vasopressor-SNP groups, the plasma and brain lidocaine concentrations at the onset of convulsions returned to the control values, although epinephrine and norepinephrine, but not phenylephrine, still decreased cumulative convulsant doses of lidocaine significantly (P < 0.01) compared with control (E + SNP = 30.8 +/- 2.9 < N + SNP = 34.8 +/- 2.8, P < 0.01) < P + SNP = 40.2 +/- 3.0 mg.kg-1, P < 0.01). The brain/plasma concentration ratios were similar for the seven groups. CONCLUSIONS: An equal degree of acute hypertension induced by these three different vasopressors may play a role in reducing the threshold (plasma and brain lidocaine concentrations) as well as the cumulative convulsant doses associated with lidocaine-induced convulsions.

Acute Disease↗
PubMed1978

Brain amines and convulsions in four strains of parathyroidectomized, pinealectomized rat.

The tendency for four strains of parathyroidectomized (PTx) rats to convulse after pinealectomy (Px) was observed in this experiment; telencephalic serotonin, norepinephrine, and dopamine were examined to note any correlation between amines and convulsions. The strains of rats tested were Sprague-Dawley, Wistar, Long-Evans, and ACI. Duration to onset of convulsions was shortest in the PTx + Px Long-Evans. No convulsions were noted in the PTx +Px ACI strain, but at least 70% of the animals in each of the other PTx + Px groups did convulse. The administration of calcium gluconate (70 mg/kg) intraperitoneally in saline did not alleviate convulsions in the PTx + PTx Sprague-Dawley. Telencephalic serotonin was lowered in the PTx +Px Wistar while norepinephrine was depressed in the PTx + Px Long-Evans rat. Dopamine levels did not change. Previous work in the PTx +Px induced convulsion has led to the implication of norephinephrine alone, but this work indicates serotonin may be involved in some strains. The need for further study of the genesis of convulsions in the PTx + Px rat is clearly indicated.

Animals↗
PubMed1997

Role of the claustrum in convulsive evolution of visual afferent and partial nonconvulsive seizure in primates.

PURPOSE: We tested cross-species validity of the role of the claustrum in the convulsive evolution of the visual afferent and amygdaloid seizure and the specificity of the claustral lesioning effect. METHODS: In 7 Senegalese baboons, we examined the effect of unilateral claustral lesioning on generalized convulsive seizures either kindled from the amygdaloid nucleus (AM) and cingulate cortex (CG) or induced by intermittent photic stimulation (IPS) after systemic administration of D,L-allylglycine (AG). RESULTS: A lesioned area common to all animals was the anterior half of the left claustrum. Postoperative restimulation of the kindled left AM or CG evoked only nonconvulsive seizures. When few convulsive seizures emerged in 1 CG-kindled animal, they were mirror image of the kindled seizure and arose from the nonlesioned right hemisphere. Restimulation of the kindled right AM or CG reactivated kindled seizures. An IPS-induced generalized convulsive seizure was transformed into a secondarily generalized seizure arising from the nonlesioned right hemisphere. CONCLUSIONS: The primate claustrum regulates the convulsive evolution of partial seizures originating from nonmotor structures such as the AM and CG and also regulates the convulsive development that follows IPS. Our findings suggest that predisposed susceptibility expressed at the claustrum may be involved in the clinical variation with respect to convulsive evolution of nonmotor partial seizures and convulsive susceptibility to IPS in human primates.

Allylglycine↗
PubMed2006

The convulsive and electroencephalographic changes produced by nonpeptidic delta-opioid agonists in rats: comparison with pentylenetetrazol.

delta-Opioid agonists produce convulsions and antidepressant-like effects in rats. It has been suggested that the antidepressant-like effects are produced through a convulsant mechanism of action either through overt convulsions or nonconvulsive seizures. This study evaluated the convulsive and seizurogenic effects of nonpeptidic delta-opioid agonists at doses that previously were reported to produce antidepressant-like effects. In addition, delta-opioid agonist-induced electroencephalographic (EEG) and behavioral changes were compared with those produced by the chemical convulsant pentylenetetrazol (PTZ). For these studies, EEG changes were recorded using a telemetry system before and after injections of the delta-opioid agonists [(+)-4-[(alphaR)-alpha-[(2S,5R)-2,5-dimethyl-4-(2-propenyl)-1-piperazinyl]-(3-methoxyphenyl)methyl]-N,N-diethylbenz (SNC80) and [(+)-4-[alpha(R)-alpha-[(2S,5R)-2,5-dimethyl-4-(2-propenyl)-1-piperazinyl]-(3-hydroxyphenyl)methyl]-N,N-diethylbenzamide [(+)-BW373U86]. Acute administration of nonpeptidic delta-opioid agonists produced bilateral ictal and paroxysmal spike and/or sharp wave discharges. delta-Opioid agonists produced brief changes in EEG recordings, and tolerance rapidly developed to these effects; however, PTZ produced longer-lasting EEG changes that were exacerbated after repeated administration. Studies with antiepileptic drugs demonstrated that compounds used to treat absence epilepsy blocked the convulsive effects of nonpeptidic delta-opioid agonists. Overall, these data suggest that delta-opioid agonist-induced EEG changes are not required for the antidepressant-like effects of these compounds and that neural circuitry involved in absence epilepsy may be related to delta-opioid agonist-induced convulsions. In terms of therapeutic development, these data suggest that it may be possible to develop delta-opioid agonists devoid of convulsive properties.

Animals↗