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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 suggested that brain serotonin (5-hydroxytryptamine or 5-HT) neurons inhibit epileptiform seizure activity. To test further this possibility, experiments were performed to determine if brain 5-HT depletion would enhance the occurrence and/or magnitude of seizures "kindled" from the amygdala or neocortex of rats. Two modes of 5-HT depletion were used: (1) radiofrequency heat lesions of the midbrain dorsal and median raphe nuclei, and (2) systemic injection of the 5-HT synthesis inhibitor, p-chlorophenylalanine (pCPA). Both modes of 5-HT depletion reliably enhanced the strength of motor convulsions kindled from the cortex. Systemic pCPA also reduced the duration of after-discharges (ADs) in cortically-stimulated rats. However, pCPA reduced rather than enhanced convulsions kindled from the amygdala. In contrast to this, raphe lesions appeared to sensitize rats to the effects of amygdaloid kindling, i.e., lesions lowered AD thresholds, AD durations and number of ADs to elicit motor convulsions. Viewed together, these data support the hypothesis that 5-HT neurons can serve to inhibit seizures. However, the lack of robustness across parameters of epileptogenesis as well as discrepant findings related to 5-HT depletion mode additionally suggest that kindled seizures affect other neuronal populations in addition to those under serotonergic influence.
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PMID:Effects of midbrain raphe lesions or systemic p-chlorophenylalanine on the development of kindled seizures in rats. 15 85

The role of brain monoamines in the anticonvulsant effect of imipramine was investigated in albino rats, against maximal electroshock-induced seizures, by using drugs with well-defined effects on brain monoamines. The results suggest a definite role for noradrenaline in imipramine anticonvulsant action. Dopamine and 5-hydroxytryptamine do not appear to be involved in this effect of imipramine.
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PMID:Role of brain monoamines in the anticonvulsant effect of imipramine in albino rats. 19 12

The time course effects of the benzoquinolizine Ro 4-1284 on spinal cord norepinephrine (NE) and 5-hydroxytryptamine (5-HT) levels were compared to the effects of this same drug on electrically-induced spinal cord seizures. The data show that a significant decrease in spinal cord NE levels and a facilitating effect on spinal cord seizures are apparent 15 minutes after Ro 4-1284 (10 mg/kg s.c.) and that both of these effects persist for at least 24 hours. Forty-eight hours after injection, the effects of Ro 4-1284 on seizure and on NE levels are completely dissipated. A significant decrease in 5-HT levels is not apparent until 1 hour after Ro 4-1284. These data suggest that noradrenergic neurons of the spinal cord act as attenuators of seizure activity. The possibility that spinal cord 5-HT also subserves a seizure attenuating function is not precluded.
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PMID:Effects of Ro 4-1284 on electrically-induced spinal cord seizures and on spinal cord norepinephrine and 5-hydroxytryptamine levels. 24 55

Brain levels of tyrosine, dopamine (DA), noradrenaline (NA), tryptophan, 5-hydroxytryptamine (5-HT), and 5-hydroxyindoleacetic acid (5-HIAA) were measured after 30, 60 and 120 min of sustained seizure activity, induced in paralyzed, artificially ventilated and anaesthetized (70% N2O) rats by administration of bicuculline (1.2 mg/kg i.v.). In separate animals the rates of accumulation of DOPA and 5-hydroxytryptophan (5-HTP) were estimated in three different brain regions after blockage of the aromatic L-amino acid decarboxylase with NSD 1015 (100 mg/kg). The tissue level of NA was markedly reduced at 30 min and remained low during 120 min of sustained epileptic seizures. In contrast, the DA concentration, being essentially unaffected at 30 min, continuously increased during the following 90 min. 5-HT decreased significantly after 30 min but returned to control levels following 60 and 120 min of seizure activity. The 5-HIAA concentration progressively increased. In all three brain regions (striatum, limbic forebrain and hemispheres) the rate of tyrosine hydroxylation increased. Tryptophan hydroxylation showed a significant increase only in the limbic forebrain. The results suggest that bicuculline-induced seizures lead to an increased functional activity in NA neurons and, at least initially, also in 5-HT neurons. In contrast, DA neurons appear to be inhibited.
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PMID:Monoamine metabolism during bicuculline-induced epileptic seizures in the rat. 30 80

Mice were made physically dependent on ethanol by a 3-day period of alcohol inhalation with small daily injections of pyrazole. During this treatment the concentrations of norepinephrine, dopamine and 5-hydroxytryptamine were increased in brain with concomitant decrease in gamma-aminobutyric acid, RNA and DNA. However, the monoamine concentrations showed complete regression to normal levels at the time of maximal withdrawal seizure when GABA level was still elevated above the control values. Brain RNA and DNA concentrations remained low at this period. During the recovery phase, the pattern of neuronal components was almost the same as was observed at maximal withdrawal seizures. Pyrazole by itself did not produce significant changes in concentrations of the neuronal components of brain.
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PMID:Neurochemical aspects of ethanol dependence and withdrawal reactions in mice. 55 9

A case report is presented of a boy with the infantile spasm syndrome beginning at eight months of age. He had a clinical course marked by increasingly severe seizures and neurological regression. After death at twenty-one months of age, autopsy of the central nervous system revealed demyelination of white matter with sparing of arcuate fibers. An earlier born male sibling had had a similar clinical pattern but died without an autopsy. During his lifetime, the patient had markedly elevated levels of 5-hydroxyindoles (a measure of serotonin) in his blood. At autopsy, the level of 5-hydroxytryptamine (serotonin) in four grey matter areas of the brain was lower than those of a control who died on the same day. This is the first case reporting a comparison of blood and central nervous system levels of 5-hydroxytrypamine in a child.
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PMID:Serotonin levels in the blood and central nervous system of a patient with sudanophilic leukodystrophy. 57 43

In an an intra-individual crossover trial depressed patients were treated with the 5-hydroxytryptamine (5-HT) precursor L-tryptophan (L-TP) and unilateral ECT, or with unilateral ECT alone. The oral dose of L-TP was 6 g the day before ECT and 3 g on the day of ECT, 4 hours before the treatment. The seizure duration was measured on EEG records. The time of the electrical stimulation needed to induce generalized seizures was similar for both treatment alternatives. Thus L-TP seems not to elevate the threshold to ECT-induced convulsions. The mean duration of a seizure was significantly shorter when the patients were treated with L-TP + ECT than when treated with ECT alone. It is suggested that L-TP exerts an inhibitory influence on the ability to sustain epileptic activity.
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PMID:Has tryptophan any anticonvulsive effect? 64 14

Seizure activity as a component of the ischemic process possibly responsible for monoamine changes described in the gerbil stroke model was the subject of this study. Abnormal motor activity suggestive of seizures developed one to three hours after unilateral ligation of the common carotid artery in approximately 50% of gerbils that exhibited signs of stroke. Reduction of cortical levels of dopamine and norepinephrine was observed only when seizures occurred in association with stroke. The levels of 5-hydroxytryptamine were reduced bilaterally in animals with and without signs of stroke and were reduced further in animals with stroke plus seizures. Further study is needed to establish whether the catecholamine changes associated with ischemia-induced seizures are primary and causative or secondary to seizure activity itself. In the ischemic brain, 5-hydroxytryptamine metabolism appears disordered independent of seizure activity. Seizure activity must be taken into account when the mechanisms of disordered monoamine metabolism are being examined in the gerbil stroke model.
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PMID:Ischemia-induced seizures and cortical monoamine levels. 65 65

1. The literature, both clinical and experimental, suggests that tricyclic antidepressants are potentially epileptogenic. Using the experimental model of epilepsy provided by the photosensitive baboon, Papio papio, the epileptic potential of four antidepressant drugs, two of which are tricyclic, has been assessed. The drugs used were imipramine 1, 10 and 20 mg/kg, chlorimipramine 1, 10 and 20 mg/kg, maprotiline 1 and 10 mg/kg and nomifensine 10 and 20 mg/kg. In a second series of experiments the 5-hydroxytryptamine (5-HT) precursor 5-hydroxytryptophan (5-HTP) 10 and 25 mg/kg has been administered before administration of imipramine 10 mg/kg and chlorimipramine 10 mg/kg. 2. The results of the experiments indicate that at 10 mg/kg imipramine, chlorimipramine and maprotiline all induce seizures and lower the seizure threshold. In contrast nomifensine at this dose did not alter the seizure threshold. 5-HTP 25 mg/kg administered before the antidepressants, abolished seizures. These results are discussed in the light of other experiments which have attempted to explain the pathophysiology of epileptic seizures following antidepressants, and it is concluded that dopaminergic mechanisms are probably responsible for the differing effect noted with nomifensine.
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PMID:Effect of nomifensine on brain amines and epilepsy in photosensitive baboons. 91 46

Mice with a genetically determined susceptibility to audiogenic seizures were utilized to analyze the ontogeny of central monoamine neurotransmission in relation to a behavior with age-specific properties. Levels of noradrenaline (NA), dopamine (DA), and 5-hydroxytryptamine (5-HT) were measured in forebrain and hindbrain regions at 14, 21, 28, and 42 days postnatal age in genetically sensitive or resistant strains of mice. An in vivo estimate of tyrosine and tryptophan hydroxylase activity was obtained at the same ages by following the accumulation of 3,4-dihydroxyphenylalanine (DOPA) and 5-hydroxytryptophan (5-HTP) respectively, after the administration of a centrally effective L-amino acid decarboxylase inhibitor (R04-4602, 800 mg/kg). At 14 days, there was a faster rate of accumulation of DOPA in both the forebrain and hindbrain of the sensitive mice compared to mice of the nonsensitive strain. At 21 days, the age of maximal sensitivity in the sensitive mice, the levels of NA were significantly lower in both regions of the sensitive mice, but the accumulation of DOPA was similar between strains at this age. There was also a slightly lower level of 5-HT in the forebrain of sensitive mice at 21 days accompanied by a slower rate of accumulation of 5-HTP in this region. In the hindbrain of the sensitive animals however, the rate of accumulation of 5-HTP was faster than in the sensitive strain. At 28 days, some impairment in mechanisms within NA-containing neurons in the sensitive mice was still apparent (including lower NA levels). At 42 days, there were no differences in amine levels, however, the levels of accumulated DOPA and 5-HTP were significantly lower in the sensitive strain. The results suggest that in the sensitive mice, developmental differences in mechanisms of monoamine storage and/or synthesis may exist which could contribute to deficient amounts of physiologically releaseable transmitter.
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PMID:Audiogenic seizures: relation to age and mechanisms of monoamine neurotransmission. 108 62


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