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

Increasing numbers of reports indicate direct effects of ovarian steroids on the central nervous system. Effects of progesterone and its metabolites on brain excitability in humans and in experimental animals have been studied. Anti-epileptic effects have been shown in cats and in women with partial epilepsy and well-defined epileptic foci. The reduced progesterone metabolite 5 alpha-pregnan-3 alpha-ol-20-one and its 5 beta analogue also decreased the epileptic activity resulting from a penicillin-induced cortical focus in cats. 5 alpha-Pregnan-3 alpha-ol-20-one protected mice against metrazol-, bicuculline- and picrotoxin-induced seizures but not against electroshock-and strychnine-induced seizures. Progesterone, 5 alpha-pregnan-3 alpha-ol-20-one and 5 beta-pregnan-3 alpha-ol-20-one also induce anaesthesia in humans and animals; in a rat model of anaesthesia 5 alpha-pregnan-3 alpha-ol-20-one was eight times more potent than methohexitone (the most potent anaesthetic barbiturate). Anaesthesia with loss of the eyelash reflex was observed in humans 75-90 seconds after the intravenous injection of 5 beta-pregnan-3 alpha-ol-20-one in lipid emulsion. The in vivo production and brain distribution of centrally active steroids has also been studied in relation to the phases of the ovarian and menstrual cycle. A subset of women with epilepsy show changes in seizure frequency in relation to hormonal variations during the menstrual cycle. In the luteal phase when progesterone levels are high the number of generalized seizures is low. It is possible that progesterone and its metabolites play a role in epileptic seizures and also in the premenstrual syndrome.
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PMID:Steroids in relation to epilepsy and anaesthesia. 229 14

L-Cycloserine dose-dependently inhibited the activity of gamma-aminobutyric acid (GABA)-transaminase (GABA-T) and elevated the level of GABA in whole mouse brain with a peak effect 3-4 hr after a single intraperitoneal injection. At a dose (30 mg/kg) which elevated the level of GABA almost 4-fold, L-cycloserine moderately increased the content of alanine and slightly reduced that of aspartate, glutamate and glycine in the brain. L-Cycloserine (10-30 mg/kg, p.o. or i.p.) prevented tonic seizures induced by 3-mercaptopropionic acid (3-MPA) and audiogenic seizures in DBA/2 mice, without affecting those evoked by pentylenetetrazol, bicuculline and electroshock. Similarly small doses of L-cycloserine reduced the level of cGMP in the cerebellum of rats, prevented its elevation by 3-MPA and attenuated the hypothalamically-elicited rage reaction in cats. Larger doses of L-cycloserine (greater than 30-100 mg/kg) impaired the performance of mice in the rotarod, chimney and horizontal wire tests, and reduced spontaneous locomotor activity of rats. Upon repeated administration the inhibitory effect of L-cycloserine on the activity of GABA-T and on seizures elicited by 3-MPA in mice increased. In contrast, the depressant action of L-cycloserine on motor performance and locomotion declined in subchronically-treated mice and rats. The levels of amino acids in brain after repeated administration did not differ markedly from those in acutely-treated mice. It is suggested that small doses of L-cycloserine, probably by increasing GABAergic inhibition, reduce hyperexcitability in the brain in acute- and subchronically-treated animals. Larger doses of L-cycloserine, possibly by inducing multiple neurochemical changes, evoke central depressant effects which diminish during subchronic treatment.
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PMID:L-cycloserine: behavioural and biochemical effects after single and repeated administration to mice, rats and cats. 301 1

The complex interactions of neurosecretions with the developing brain suggest that it has multiple site and time-specific vulnerabilities that may contribute to the pathogenesis of several forms of epilepsy, yet, on the other hand, may provide several new forms of therapy. Catamenial seizures can be clearly related to hormonal changes, although other factors are important, such as altered drug metabolism during menses. Progesterone appears to be especially effective in treating seizures. Optimal forms of treatment for catamenial epilepsy have not been established; however, several forms of progesterone are available and may be helpful, including those in oral contraceptives. Special care in the selection of oral contraceptives may be an important adjunct in caring for women with epilepsy. Altered secretion of neurohormones suggests important clues to the sexual dysfunction and psychopathology associated with temporal lobe epilepsy. New approaches to these patients include the clinical evaluation for sexual dysfunction along with the measurement of prolactin, testosterone, LH, and FSH levels, and treatment of sexual dysfunction by the effective use of anticonvulsants. Elevated plasma hormones (especially prolactin) following seizures can help to distinguish true seizures from pseudoseizures. Effects of anticonvulsant drugs on endocrine function are important, particularly with respect to their ability to lower the efficacy of oral contraceptives by competitive binding. A number of hormonal changes have been described with several drugs, which suggest that their complex central and peripheral effects might help to explain some aspects of normal hormone activity as well as some common side effects of the drugs.
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PMID:Hormones and epilepsy. 354 May 87

In experiments on male mice, we studied the effects of gamma-aminobutyric acid (GABA), angiotensin II (AT II), administered intracerebroventricularly, diazepam, injected intraperitoneally, and combinations of GABA + AT II and diazepam + AT II on convulsive seizures induced by pentylenetetrazol (PTZ) (80 mg/kg subcutaneously) and 3-mercaptopropionic acid (3-MPA) (40 mg/kg intraperitoneally). The anticonvulsant effects of GABA and diazepam on PTZ-induced seizures were increased by AT II in doses which did not significantly influence seizures. AT II applied together with GABA or diazepam in ineffective doses provoked a strong anticonvulsant effect on both PTZ- and 3-MPA-induced seizures. These results indicate that the anticonvulsant effects of GABA and diazepam on PTZ- and 3-MPA-induced seizures might effectively be potentiated by the octapeptide AT II. It is suggested that AT II operates as an endocoid acting on GABA, respectively benzodiazepine recognition sites in the CNS.
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PMID:Interactions between angiotensin II, GABA and diazepam in convulsive seizures. 373 89

We studied eight women who had complex partial seizures and anovulatory cycles or inadequate luteal phases. Progesterone suppositories were given during the premenstrual phase or entire second half of the cycle in doses of 50 to 400 mg q12h. Antiseizure medication levels were kept in the therapeutic range. Average monthly seizure frequency declined by 68% (p less than 0.05, Wilcoxon matched-pairs test) in a 3-month treatment period compared with the 3 months prior to therapy, and six of the eight women had fewer seizures. None experienced more seizures or disruption of menses. Transient tiredness and depression were noted in some when progesterone dosage was raised above minimally effective levels. These symptoms cleared within 48 hours of lowering the dosage. The value of intermittent natural progesterone therapy as a safe, well-tolerated, and effective adjunct to antiseizure therapy should be assessed further.
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PMID:Intermittent progesterone therapy and frequency of complex partial seizures in women with menstrual disorders. 378 77

Clinical epileptologists since Gowers have known that hormones may affect central nervous system excitability. Progesterone has been noted to have anticonvulsant properties in both clinical and animal studies. The effect of progesterone on central nervous excitability in the immature animal, however, has not been studied. This study evaluated the effects of progesterone on the rate of kindling in adult and immature animals. While progesterone has no effect on kindling in the adult animal, in the immature animal progesterone markedly inhibited kindling, preventing generalization of seizures. This study demonstrates that progesterone has a marked age-dependent effect on neuronal excitability.
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PMID:The effect of progesterone on kindling: a developmental study. 648 53

This open trial assessed the effects of adjunctive progesterone therapy on seizure frequency in 25 women with catamenial exacerbation of complex partial (CPS) and secondary generalized motor (SGMS) seizures. Progesterone was well tolerated by 23 of the 25 women and had readily reversible dose-related side effects of asthenia and emotional depression in two. Eighteen women (72%) experienced a decline in seizure frequency during a 3-month treatment period compared with the 3 months prior to therapy (p < 0.01). Average daily CPS frequency declined by 54% (p < 0.01), SGMS by 58% (p < 0.02).
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PMID:Progesterone therapy in women with complex partial and secondary generalized seizures. 767 23

Glutamate decarboxylase (EC 4.1.1.15, GAD) activity was studied in the brain of 12-day-old and adult rats treated with 3-mercaptopropionic acid (3-MPA), an inhibitor of GAD competitive with glutamate. Control GAD activity in the brains of immature animals (91.8 +/- 18.2 nmol/h/mg of protein) was lower than that of the adult rats (228 +/- 37.5 nmol/h/mg of protein). Brain GAD inhibition in adult rats was 58% at the onset of seizures (9 min on the average after administration of 70 mg 3-MPA/kg). At the same time, 3-MPA-treated young rats exhibited 76% inhibition of GAD despite the fact that at 9 min these animals were not yet having seizures. At the onset of seizures (19 min after 3-MPA on the average) their GAD activity remained at the same level. The difference between the groups was not related to the presence of the coenzyme pyridoxal-5'-phosphate in the enzyme assay. The inhibition of GAD by 3-MPA in vitro in the immature and adult brains was similar (Ki at 5.1 microM and 4.8 microM concentrations of 3-MPA, respectively). Identical values were found for Km of GAD (at 4.5 mM concentration of L-glutamate). Calculations based on the results suggest that 3-MPA enters the immature brain more easily than the brain of the adult animals. While GAD inhibition by 3-MPA is the primary cause of seizures, their onset is influenced by other factors, in which the immature brain differs from the adult one and which may include less sensitivity to GABA decrease due to relative overactivity of the GABA system.
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PMID:Differences between immature and adult rats in brain glutamate decarboxylase inhibition by 3-mercaptopropionic acid. 779 89

Progesterone increases cocaine's cardiovascular toxicity in sheep and rats. To determine whether progesterone enhances the lethality of cocaine, nonpregnant female rats were treated with either IM progesterone (P4) or vehicle, and pregnant rats (Preg) were untreated. The rats received one IP injection of cocaine at a dose between 25-75 mg/kg and were observed for seizures and/or death. All 62 rats that died did so within 17 min, preceded by seizures in 90.3%. Mean times-to-seizure and times-to-death, and mean lethal serum cocaine concentrations did not differ among groups. Serum progesterone levels (ng/ml +/- SEM) at the time of death were different among groups: 24 +/- 1.7 (C), 102 +/- 6.4 (P4), and 139 +/- 5.2 (Preg). Logistic regression dose/fatality curves, LD50s, and LD10s for the pregnant, progesterone, and control groups were not significantly different from one another. Though progesterone has enhanced cocaine's cardiac toxicity in some studies, it does not increase the risk of death from acute cocaine exposure in rats.
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PMID:Cocaine LD50 in Long-Evans rats is not altered by pregnancy or progesterone. 793 64

The convulsant action of 3-mercaptopropionic acid (3-MPA), a known inhibitor of glutamate decarboxylase activity, was studied in 7-, 12-, 18- and 25-day-old rats and in adult animals. 3-MPA elicited predominantly clonic, minimal seizures as well as generalized tonic-clonic (major) seizures at all developmental stages studied. The CD50 for major seizures did not change during development; CD50 for minimal seizures was significantly lower in 18-day-old rats than in older animals. Latency to the onset of seizures was shortest in 18-day-old rats and extremely long in 12- and, especially, in 7-day-old rats. This long latency might signify either changing molecular properties of glutamate decarboxylase during development or slow turnover of GABA at early postnatal stages. Electrocorticographic recordings demonstrated sharp EEG components in the frontal region as a first sign of 3-MPA action, and seizure patterns exhibited similar developmental changes as found with other seizure models (a decrease in duration of individual graphoelements and an increase in synchronization among various cortical regions). This indicates the primary importance of brain maturation in the expression of epileptic EEG phenomena. The correlation between EEG and motor phenomena was poor in the youngest animals and it ameliorated with age, but it never became perfectly coincidental.
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PMID:Motor and electrocorticographic epileptic activity induced by 3-mercaptopropionic acid in immature rats. 824 36


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