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

Dihydroergotoxine administration shortened the latency of allylglycine-and picrotoxin-induced convulsions in rats and increased the incidence of convulsions elicited by picrotoxin, i.e., it lowered ED50 for picrotoxin. The same drug (0.1-10.0 mg/kg) decreased the levels of gamma-aminobutyric acid (GABA) in the caudate nucleus and cingulate cortex, but enhanced the aminooxyacetic acid induced accumulation of GABA indicating an increased synthesis of GABA in these brain regions. The concentrations of 5-hydroxytryptamine, 5-hydroxyindoleacetic acid, noradrenaline, and dopamine in the whole rate brain were not affected with doses of dihydroergotoxine up to 10.0 mg/kg, but this dose of the drug slowed down the turnover of dopamine, as evidenced by a diminished disappearance of dopamine induced by alpha-methyl-p-tyrosine administration. The results suggest that dihydroergotoxine decreases GABA-ergic transmission and, therefore, presumably lowers the seizure threshold.
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PMID:Dihydroergotoxine and the Seizure Threshold. 729 68

The effects of selected drug treatments on spinal cord norepinephrine (NE), dopamine (DA), and 5-hydroxytryptamine (5-HT) were compared to the effects of these same treatments on electrically-induced spinal cord seizure. Depletion of monoamine stores by reserpine facilitated spinal cord seizures. In contrast, L-DOPA, given to animals pretreated with iproniazid, exerted an anticonvulsant effect and elevated spinal cord NE and DA levels. L-DPOA administered alone produced a substantial elevation in DA levels but had no effect on spinal cord seizures. Iproniazid had no effect on monoamines, whereas it facilitated seizure activity. These observations support the concept that spinal cord noradrenergic, but not 5-hydroxytryptaminergic or dopaminergic neurons act as attenuators of convulsive activity. The effect of iproniazid on spinal cord seizures, in the absence of an observed alteration in monoamine levels, provides evidence that this effect is mediated through non-monoaminergic mechanisms.
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PMID:The effects of reserpine, iproniazid and L-dopa on electrically-induced spinal cord seizures. 742 21

Intracerebroventricular administration to mice of 5,7-dihydroxytryptamine at a dose of 300 micrograms resulted in convulsive behaviour and death (latency 7.6 +/- 1.7 min.). Pretreatment with dizocilpine or chlormethiazole resulted in a dose dependent inhibition of the convulsive behaviour. A dose of dizocilpine of 0.12 mumol/kg or chlormethiazole at a dose of 150 mumol/kg prevented seizures for 30 min. Injection of 5,7-dihydroxytryptamine (75 micrograms, intracerebroventricularly) produced an approximate 50% neurotoxic loss of cerebral 5-hydroxytryptamine (5-HT) and its metabolite 5-hydroxyindole acetic acid (5-HIAA) 8 days later. This loss was not prevented by administration of either dizocilpine (4.5 mumol/kg intraperitoneally) or chlormethiazole (300 mumol/kg intraperitoneally) given 5 min. before and 55 min. after the 5,7-dihydroxytryptamine injection. It is proposed that chlormethiazole and dizocilpine may protect against 5,7-dihydroxytryptamine-induced seizures because of their anticonvulsant activity, but that they do not prevent the neurotoxic effects of the compound. The data also suggest that the neurotoxic effects of substituted amphetamines such as 3,4-methylene dioxymethamphetamine (MDMA or Ecstasy) do not result from the formation of a 5,7-dihydroxytryptamine like compound.
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PMID:Chlormethiazole and dizocilpine block the behavioural, but not the neurotoxic effects of 5,7-dihydroxytryptamine in mice. 751 15

1. This study was designed to evaluate further the role of 5-hydroxytryptamine (5-HT) in regulating susceptibility and/or intensity of audiogenic seizures in genetically epilepsy-prone rats. 2. The effects of sertraline, a highly selective and potent inhibitor of 5-HT uptake, on both the intensity of the audiogenic seizures and the extracellular concentrations of 5-HT in the thalamus were evaluated in severe seizure genetically epilepsy-prone rats. 3. Sertraline (7.5, 15 and 30 mg kg-1, i.p.) produced a dose-dependent reduction in the intensity of the audiogenic seizures. 4. Brain microdialysis studies showed that the same doses of sertraline also caused dose-dependent increases in the extracellular 5-HT concentration in the thalamus of the freely moving rats. 5. The peak anticonvulsant effect correlated temporally with the peak increases in the extracellular 5-HT concentration for this drug. 6. It is concluded that enhancement of 5-hydroxytryptaminergic transmission may contribute to the anticonvulsant effect of sertraline in severe seizure genetically epilepsy-prone rats. 7. The present results coupled with earlier investigations support the hypothesis that 5-HT plays an anticonvulsant role in genetically epilepsy-prone rats.
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PMID:Further evidence of anticonvulsant role for 5-hydroxytryptamine in genetically epilepsy-prone rats. 758 62

Tetanus toxin is a potent neurotoxin which produces seizures and usually death in mammals. In the present study, we have investigated the effect of tetanus toxin on extracellular basal and evoked release of 5-hydroxytryptamine (5-HT), dopamine (DA) and their metabolites in vivo, 7 days after toxin injection into the hippocampus of rats. Tetanus toxin decreased both basal and evoked release of 5-HT and DA. The 5-HT metabolite 5-hydroxyindoleacetic acid (5-HIAA) was not significantly decreased in the extracellular space. Of the DA metabolites 3,4-dihydroxyphenylacetic acid (DOPAC) concentration was decreased while that of homovanillic acid (HVA) was unchanged. These findings are considered in light of the possible contributory role that a decrease in monoamine concentration in the hippocampus might have in the effects of tetanus toxin.
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PMID:Effect of tetanus toxin on basal and evoked release of 5-hydroxytryptamine and dopamine in rat hippocampus in vivo. 760 49

3,4-Methylenedioxymethamphetamine (MDMA or "Ecstasy") was first synthesised 80 years ago, but has recently received prominence as an illegally synthesised recreational drug of abuse. There is a widely held belief among misusers that it is safe. In the last 2-3 years there have been a number of reports of the drug producing severe acute toxicity and death and there are concerns that it may cause long term toxic damage to 5-hydroxytryptamine (5-HT) nerve terminals. There is a considerable literature on the acute pharmacological effects of MDMA in experimental animals, and this is reviewed. The drug produces both hyperthermia and the "serotonin syndrome", a series of behavioural changes which result from increased 5-HT function. Acute clinical toxicity problems following MDMA ingestion also include hyperthermia and the appearance of the serotonin syndrome. The hyperthermia appears to precipitate other severe clinical problems and the outcome can be fatal. In agreement with others, we suggest that the recent increase in the number of reports of MDMA toxicity probably results from the widespread use of the drug at all night dance parties or "raves". The phenomenon of amphetamine aggregation toxicity in mice was reported 40 years ago. If applicable to MDMA-induced toxicity in humans, all the conditions necessary to induce or enhance toxicity are present at raves: crowded conditions (aggregation), high ambient temperature, loud noise and dehydrated subjects. Administration of MDMA to rodents and non-human primates results in a long term neurotoxic decrease in 5-HT content in several brain regions and there is clear biochemical and histological evidence that this reflects neurodegeneration of 5-HT terminals. Unequivocal data demonstrating that similar changes occur in human brain do not exist, but limited and indirect clinical evidence gives grounds for concern. There are also data suggesting that long term psychiatric changes can occur, although there are problems of interpretation and these are reviewed. Suggestions for the rational treatment of the acute toxicity are made on the basis of both pharmacological studies in animals and current clinical practice. Cases presenting clinically are usually emergencies and unlikely to allow carefully controlled studies. Proposals include decreasing body temperature (possibly with ice), the use of dantrolene and anticonvulsant and sedative medication, particularly benzodiazepines. The use of neuroleptics requires care because of the theoretical risk of producing the neuroleptic malignant syndrome and the possibility of precipitating seizures. In rats, chlormethiazole antagonises the hyperthermia produced by MDMA and has been shown clinically to block MDMA-induced convulsive activity.
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PMID:Review of the pharmacology and clinical pharmacology of 3,4-methylenedioxymethamphetamine (MDMA or "Ecstasy"). 767 58

Serotonin (5-hydroxytryptamine, 5-HT) is a monoaminergic neurotransmitter that is believed to modulate numerous sensory, motor and behavioural processes in the mammalian nervous system. These diverse responses are elicited through the activation of a large family of receptor subtypes. The complexity of this signalling system and the paucity of selective drugs have made it difficult to define specific roles for 5-HT receptor subtypes, or to determine how serotonergic drugs modulate mood and behaviour. To address these issues, we have generated mutant mice lacking functional 5-HT2C receptors (previously termed 5-HT1C), prominent G-protein-coupled receptors that are widely expressed throughout the brain and spinal cord and which have been proposed to mediate numerous central nervous system (CNS) actions of serotonin. Here we show that 5-HT2C receptor-deficient mice are overweight as a result of abnormal control of feeding behaviour, establishing a role for this receptor in the serotonergic control of appetite. Mutant animals are also prone to spontaneous death from seizures, suggesting that 5-HT2C receptors mediate tonic inhibition of neuronal network excitability.
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PMID:Eating disorder and epilepsy in mice lacking 5-HT2c serotonin receptors. 860 65

The thresholds for pentylenetetrazol and lidocaine-induced clonic convulsions were significantly influenced by manipulation of brain biogenic amines. Pretreatment with inhibitors of monoamine synthesis, alpha-methyl-p-tyrosine and p-chlorophenylalanine, caused significant decreases in brain monoamine contents and pentylenetetrazol seizure threshold, while the threshold for lidocaine-induced convulsions was significantly increased by either treatment. Moreover, the inhibitor of dopamine-beta-hydroxylase, disulfiram, caused significant decrease in brain noradrenaline (NA) and significant increase in brain dopamine (DA) contents. The threshold for pentylenetetrazol-induced convulsions was decreased by treatment with disulfiram, while that of lidocaine was increased by the same treatment. Furthermore, treatment with L-dihydroxyphenylalanine (L-DOPA) caused significant increase in brain DA contents, while 5-hydroxytryptophan (5-HTP) treatment caused significant increase in brain 5-hydroxytryptamine (5-HT) contents, but the thresholds for lidocaine and pentylenetetrazol-induced convulsions were not influenced by either treatment. These results may suggest that the brain monoaminergic systems, different from their ability to inhibit control of pentylenetetrazol seizures, act to potentiate lidocaine-induced convulsions.
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PMID:Alterations of lidocaine and pentylenetetrazol-induced convulsions by manipulation of brain monoamines. 780 Jun 57

The effect of 1-[3-(trifluoromethyl)phenyl] piperazine (TFMPP), a 5-hydroxytryptamine (5-HT) receptor agonist, on the threshold for maximal electroconvulsions was studied in mice. TFMPP in intraperitoneal (i.p.) doses of 10, 20 and 40 mg/kg increased the convulsive threshold (the amperage necessary to produce the hindleg tonic extensor component of seizures in 50% of animals) by 28, 60, and 85%, respectively. The effect of TFMPP (20 mg/kg) was dose-dependently blocked by 1-(2-methoxyphenyl)-4-[4-(2-phthalimido)butyl] piperazine (NAN-190), prazosin, spiperone, mesulergine, ketanserin, and ritanserin. On the other hand, pindolol and cyanopindolol had no effect on the convulsive threshold increased by TFMPP. The results indicate that the TFMPP-induced decrease in the susceptibility to seizures is connected to stimulation of 5-HT2 or of both 5-HT1C and 5-HT2 receptors. Moreover, alpha 1-adrenoceptors also appear to be engaged in this effect.
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PMID:Role of 5-hydroxytryptamine receptor subtypes in the 1-[3-(trifluoromethyl)phenyl] piperazine-induced increase in threshold for maximal electroconvulsions in mice. 808 39

Rats subjected to structural brain damage induced by sustained convulsions triggered by systemic administration of pilocarpine (PILO) are a useful model for investigation of the mechanisms essential for seizure generation and spread in rodents. After PILO administration, three distinct phases are observed: (a) an acute period of 1-2 days' duration corresponding to a pattern of repetitive limbic seizures and status epilepticus; (b) a seizure-free (silent) period characterized by a progressive return to normal EEG and behavior of 4-44 days' duration; and (c) a period of spontaneous recurrent seizures (SRS) starting 5-45 days after PILO administration and lasting throughout the animal's life. PILO (320-350 mg/kg intraperitoneally, i.p.) was administered to rats, and the content of hippocampal monoamines and amino acids was measured in the acute, silent, and SRS periods by liquid chromatography. Norepinephrine (NE) level was decreased during all periods whereas dopamine (DA) content was increased. Serotonin (5-hydroxytryptamine, 5-HT) was increased only in the acute period. Utilization rate measurement of monoamines showed increased NE consumption and decreased DA consumption during all phases. 5-HT utilization rate was increased only in the acute period. Amino acid content showed a decrease in aspartate (ASP) and glutamate (GLU) concentrations associated with increased gamma-aminobutyric acid (GABA) level during the acute period. The silent phase was characterized by a decrease in glycine (GLY) and GABA levels and an increase in GLU concentration. The SRS period showed an increase in all amino acid concentrations. These findings show important neurochemical changes in the course of establishment of an epileptic focus after brain damage induced by status epilepticus triggered by pilocarpine.
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PMID:Spontaneous recurrent seizures in rats: amino acid and monoamine determination in the hippocampus. 811 29


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