Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0036572 (seizures)
 80,221 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Tumor necrosis factor (TNF)-alpha is a proinflammatory cytokine acting on two distinct receptor subtypes, namely p55 and p75 receptors. TNF-alpha p55 and p75 receptor knockout mice were previously shown to display a decreased or enhanced susceptibility to seizures, respectively, suggesting intrinsic modifications in neuronal excitability. We investigated whether alterations in glutamate system function occur in these naive knockout mice with perturbed cytokine signaling that could explain their different propensity to develop seizures. Using Western blot analysis of hippocampal homogenates, we found that p55(-/-) mice have decreased levels of membrane GluR3 and NR1 glutamate receptor subunits while GluR1, GluR2, GluR6/7 and NR2A/B were unchanged as compared to wild-type mice. In p75(-/-) mice, GluR2, GluR3, GluR6/7 and NR2A/B glutamate receptor subunits were increased in the hippocampus while GluR1 and NR1 did not change. Extracellular single-cell recordings of the electrical activity of hippocampal neurons were carried out in anesthetized mice by standard electrophysiological techniques. Microiontophoretic application of glutamate increased the basal firing rate of hippocampal neurons in p75(-/-) mice versus wild-type mice, and this effect was blocked by 2-amino-5-phosphopentanoic acid and 6-nitro-7-sulfamoyl-benzo(f)quinoxaline-2,3-dione denoting the involvement of N-methyl-D-aspartic acid and AMPA receptors. In p55(-/-) mice, hippocampal neurons responses to glutamate were similar to wild-type mice. Spontaneous glutamate release measured by in vivo hippocampal microdialysis was significantly decreased only in p55(-/-) mice. No changes were observed in KCl-induced glutamate release in both receptor knockout mice strains versus wild-type mice. These findings highlight specific molecular and functional interactions between p55 and p75 receptor-mediated signaling and the glutamate system. These interactions may be relevant for controlling neuronal excitability in physiological and pathological conditions.
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PMID:Molecular and functional interactions between tumor necrosis factor-alpha receptors and the glutamatergic system in the mouse hippocampus: implications for seizure susceptibility. 1928 15

Anti-NMDA receptor encephalitis is a treatment-responsive encephalitis associated with anti-NMDA receptor antibodies, which bind to the extracellular conformal epitope in NR1/NR2 heteromers of the NMDA receptor, although recent data have demonstrated that its critical epitope region resides in the NR1 subunit. This disorder usually develops in young women with ovarian teratoma, who typically present with prominent psychiatric symptoms, often preceded by a common cold-like illness. Most cases develop seizures, followed by an unresponsive/catatonic state, prolonged cloudiness of consciousness, central hypoventilation, bizarre dyskinesias, and autonomic symptoms. Brain MRI is often unremarkable. CSF reveals nonspecific changes. EEG usually shows diffuse slowing without paroxysmal discharges. Tumor occurrence was initially believed to be 100%, but now it is estimated to comprise 58% of all cases, 62% in women and 22% in men. The median age at onset is 23 years, but it develops between 5 to 76 years. Although early tumor resection with immunotherapy is recommended, spontaneous recovery also occurs. The pathogenesis remains unknown; however, a recent study demonstrated that the antibodies reversibly inhibit the clustering of the NMDA receptor on the neuronal cell membrane. Based on symptomatology, we speculate that an antibody-mediated inhibition of the NMDA receptor on presynaptic GABAergic interneurons may reduce the release of GABA, causing the disinhibition of postsynaptic glutamatergic transmission, excessive release of glutamate in the prefrontal/subcortical structures, and glutamate and dopamine dysregulation. Acute juvenile female non-herpetic encephalitis (AJFNHE) has been proposed as a distinct clinical entity in Japan independently of tumor presence since 1997, when 5 young women with encephalitis were reported. A recent study suggested that these disorders are identical.
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PMID:[Anti-NMDA receptor antibody-mediated encephalitis/encephalopathy]. 1936 96

The N-methyl-d-aspartate receptor (NMDAR) is critically involved in learning and memory, neuronal survival, as well as neuroexcitotoxicity and seizures. We hypothesize that even mild reductions in the numbers of hippocampal NMDARs could impair learning and memory, whereas increasing receptor activity would facilitate learning but reduce seizure threshold. We developed novel gene transfer strategies assisted by an adeno-associated viral vector 1/2 to bi-directionally modulate expression levels of the NR1 protein in rat hippocampus. Functional consequences of the altered NR1 expression were examined in the acute seizure model, and on normal processes of fear memory and neurogenesis. We found that knocking down NR1 protected against seizures at the expense of impaired learning, as predicted. Paradoxically, NR1 overexpression not only increased fear memory and neurogenesis, but also delayed onset of more severe seizures. In conclusion, the observed consequences of NR1 knockdown and overexpression underscore NMDAR requirement for neuronal plasticity, and are in agreement with its dichotomous functions.
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PMID:Knockdown and overexpression of NR1 modulates NMDA receptor function. 1939 26

Systemic administration of the potassium channel blocker 4-aminopyridine (4-AP) elicits acute convulsions. Synchronized tonic-clonic activity develops during the first hour after the treatment. However, subsequent chronic spontaneous seizures do not appear which suggests changes in neuronal excitability. The aim of our present work was to evaluate alterations in the glutamatergic transmission in the somatosensory cortex of rats following daily, brief convulsions elicited by 4-AP treatment. Changes in general neuronal excitability and pharmacological sensitivity of glutamate receptors were tested in ex vivo electrophysiological experiments on brain slices. In parallel studies quantitative changes in subunit composition of glutamate receptors were determined with immunohistoblot technique, together with the analysis of kainate induced Co2+ uptake. The results of our coordinated electrophysiological, receptor-pharmacological and histoblot studies demonstrated that repeated, daily, short convulsions resulted in a significant decrease of the general excitability of the somatosensory cortex together with changes in ionotropic glutamate receptor subunits. The relative inhibitory effect of the AMPA receptor antagonist, however, did not change. The NMDA receptor antagonist exerted somewhat stronger effect in the slices from convulsing animals. 4-AP pretreatment resulted in the attenuation of kainate induced Co2+ uptake, which suggests either reduction in non-NMDA receptors numbers or reduction in their Ca2+ permeability. Repeated seizures decreased GluR1-4 AMPA receptor subunit levels in all cortical layers with a relaitve increase in GluR1 subunits. While the principle NR1 NMDA receptor subunit showed no significant change, the staining density of NR2A subunit increased. These changes in ionotropic glutamate receptors are consistent with reduced excitability at glutamatergic synapses following repeated 4-AP induced seizures.
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PMID:Repeated 4-aminopyridine induced seizures diminish the efficacy of glutamatergic transmission in the neocortex. 1944 32

Tosyl-polyamine derivatives such as N-{4-[4-(guanidinobutylamino)-butylamino]butyl}-4-methylbenzenesulfonamide trihydrochroride (TsHSPMG) have been found to strongly inhibit macroscopic currents through heteromeric N-methyl-D-aspartate (NMDA) receptors (NR1/NR2A, NR1/NR2B) and Ca(2+)-permeable alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (homomeric glutamate receptor 1) receptors expressed in Xenopus laevis oocytes on voltage-clamp recording. In the present study, it was found that the inhibition of NMDA receptor activity induced by tosyl-polyamine derivatives was voltage-dependent. Some mutations located in the intracellular region of the channel pore, such as NR1 E621Q and NR2B W607L, reduced the inhibition by tosyl-polyamine derivatives, suggesting that tosyl-polyamine derivatives penetrate deeply into the channel pore of NMDA receptors. The neuroprotective effects of tosyl-polyamine derivatives against cell injury caused by NMDA were investigated in cultured rat hippocampal neurons. Addition of 1 microM TsHSPMG to medium ablated the neurotoxicity induced by NMDA, and a similar effect was observed with 30 microM memantine. The neuroprotective effects of tosyl-polyamine derivatives on NMDA-induced seizures in mice were also assayed. Intracerebroventricular or intravenous injection of TsHSPMG (0.1 or 0.5 mg/kg) decreased the seizures induced by intraperitoneal injection of NMDA in mice. These findings indicate that tosyl-polyamine derivatives exhibit neuroprotective effects not only in primary cultured neurons but also in mice.
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PMID:Neuroprotection by tosyl-polyamine derivatives through the inhibition of ionotropic glutamate receptors. 1964 42

A 21-year-old woman was admitted to hospital with a diagnosis of acute psychotic mania, but developed, over approximately 6 weeks, seizures, delirium, catatonia, movement disorder and autonomic dysfunction. She was found to have antibodies to N-methyl-D-aspartate (NMDA) NR1-NR2 receptors in both serum and cerebrospinal fluid, consistent with anti-NMDA-receptor encephalitis, a severe, potentially lethal but treatment-responsive encephalitis often associated with ovarian tumour. With aggressive immunotherapy and bilateral oophorectomy, she recovered over a period of 14 months from her initial presentation. No ovarian tumour was identified.
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PMID:Acute psychiatric illness in a young woman: an unusual form of encephalitis. 1974 54

The pathophysiology of schizophrenia may involve reduced NMDA receptor function and experimental models of NMDA receptor hypofunction have proven useful for characterizing neurobiological abnormalities potentially relevant to schizophrenia. The present study assessed behavioral responses and induction of Fos after administration of kainic acid to wild type mice (NR1(+/+)) and mice with genetically reduced NMDA receptor expression (NR1(neo/neo)). At a dose of 20 mg/kg, kainic acid induced lethal seizures in 100% of the NR1(neo/neo) mice tested but produced no lethal seizures in the wild type mice. The NR1(neo/neo) mice also exhibited enhanced behavioral responses to kainic acid at a dose of 15 mg/kg but no lethal seizures were produced by this dose. A greater induction of Fos was observed in neocortical and limbic cortical regions of the NR1(neo/neo) compared to NR1(+/+) mice after administration of 15 mg/kg kainic acid. In contrast, there were no differences between the genotypes in kainic acid induced Fos in the amygdala, hippocampus, lateral septum, and nucleus accumbens. In order to determine if altered behavioral phenotypes of the NR1(neo/neo) mice could be related to increased sensitivity of kainate receptors to endogenous glutamate, effects of the highly selective kainate antagonist LY382884 were examined. The kainate antagonist reduced the exaggerated acoustic startle responses, deficits in prepulse inhibition of acoustic startle, and motor hyperactivity in the NR1(neo/neo) mice. These findings suggest that selective kainate receptor antagonists could be novel therapeutic candidates for schizophrenia.
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PMID:Increased sensitivity to kainic acid in a genetic model of reduced NMDA receptor function. 1984 Jul 78

Seizures early in life cause long-term behavioral modifications, namely long-term memory deficits in experimental animals. Since caffeine and adenosine A(2A) receptor (A(2A)R) antagonists prevent memory deficits in adult animals, we now investigated if they also prevented the long-term memory deficits caused by a convulsive period early in life. Administration of kainate (KA, 2 mg/kg) to 7-days-old (P7) rats caused a single period of self-extinguishable convulsions which lead to a poorer memory performance in the Y-maze only when rats were older than 90 days, without modification of locomotion or anxiety-like behavior in the elevated-plus maze. In accordance with the relationship between synaptotoxicity and memory dysfunction, the hippocampus of these adult rats treated with kainate at P7 displayed a lower density of synaptic proteins such as SNAP-25 and syntaxin (but not synaptophysin), as well as vesicular glutamate transporters type 1 (but not vesicular GABA transporters), with no changes in PSD-95, NMDA receptor subunits (NR1, NR2A, NR2B) or alpha-amino-3-hydroxy-5-methylisoxazole-4-propionate receptor subunits (GluR1, GluR2) compared with controls. Caffeine (1 g/L) or the A(2A)R antagonist, KW6002 (3 mg/kg) applied in the drinking water from P21 onwards, prevented these memory deficits in P90 rats treated with KA at P7, as well as the accompanying synaptotoxicity. These results show that a single convulsive episode in early life causes a delayed memory deficit in adulthood accompanied by a glutamatergic synaptotoxicity that was prevented by caffeine or adenosine A(2A)R antagonists.
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PMID:Caffeine and an adenosine A(2A) receptor antagonist prevent memory impairment and synaptotoxicity in adult rats triggered by a convulsive episode in early life. 1987 34

Alterations in N-methyl-d-aspartate receptor (NMDAR) protein levels or subcellular localization in brain after chronic ethanol exposure may contribute to withdrawal-associated seizures and neurotoxicity. We have investigated synaptic localization of NMDARs in cultured hippocampal pyramidal neurons after prolonged (7 days) exposure to, and acute withdrawal from, 80 mM ethanol using fluorescence immunocytochemistry techniques. After chronic ethanol exposure, there was a significant increase in the clustering of NR1 and NR2B subunits and their colocalization with the synaptic proteins synaptophysin and postsynaptic density protein 95, respectively. There was also increased expression of NR1 variants containing the C2' cassette after chronic ethanol exposure. The ethanol-induced synaptic clustering and colocalization were rapidly reversed within 4 h after ethanol withdrawal. Surface labeling of NR2B subunits suggested that this rapid reversal involved lateral receptor movement to extrasynaptic sites rather than internalization of receptors. Receptor removal from the synapse during ethanol withdrawal was associated with changes in the phosphorylation state of NR2B Ser1480, controlled by the protein kinase CK2. The redistribution of NMDAR to synapses produced by long-term ethanol exposure, as well as the rapid removal during withdrawal, may not only affect neuronal withdrawal hyperexcitability but also may sensitize the system to subsequent synaptic plasticity.
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PMID:Phosphorylation regulates removal of synaptic N-methyl-D-aspartate receptors after withdrawal from chronic ethanol exposure. 2000 87

Recently a new category of treatment-responsive encephalitis has been proposed associated with antibodies against neuronal cell membrane antigens, including VGKC, NMDA receptor (NMDAR) and AMPA receptor. Anti-NMDAR encephalitis is caused by the antibodies, which bind to extracellular conformal epitope in the NR1/NR2 heteromers of the NMDAR. The antibodies are usually detected in CSF/serum of young women with ovarian teratoma (OT), who typically developed schizophrenia-like psychiatric symptoms. Most patients developed seizures, followed by unresponsive/catatonic state, central hypoventilation, and bizarre orofacial-limb dyskinesias. Based on symptomatology and current NMDAR hypofunction hypothesis in schizophrenia, we speculated that the antibodies might cause inhibition of NMDAR in presynaptic GABAergic interneurons, causing a reduction of release of GABA. This results in disinhibition of postsynaptic glutamatergic transmission, excessive release of glutamate in the prefrontal/subcortical structures, and glutamate/dopamine dysregulation. Recent studies demonstrated that the antibodies cause reversible reduction in the numbers of cell-surface NMDAR and NMDAR clusters in postsynaptic dendrites, suggesting antibodies-mediated decreased function of NMDAR. Early tumor resection with immunotherapy is recommended in OT-positive cases but not in OT-negative cases. However, exploratory laparotomy may increase the chance to identify microscopic teratoma and improve the outcome if patients who were refractory to immunotherapy had anti-NMDAR antibodies and ovarian cyst.
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PMID:[Unique clinical features and pathophysiology of anti-NMDA receptor encephalitis]. 2003 Feb 7


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