Differential display PCR reveals novel targets for the mood-stabilizing drug valproate including the molecular chaperone GRP78.
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Differential display polymerase chain reaction was used to identify genes regulated by the mood-stabilizing drug valproate (VPA). Four differentially displayed valproate-regulated gene fragments were isolated in rat cerebral cortex after i.p. injection of sodium VPA (300 mg/kg) for 3 weeks, and their expression was confirmed by Northern and slot blot analysis in rat cerebral cortex and C6 glioma cells. Sequencing analysis revealed three previously unidentified cDNA fragments in addition to a sequence with 100% homology with a molecular chaperone, 78-kDa glucose-regulated protein (GRP78). VPA treatment did not increase mRNA expression of 70-kDa heat shock protein, which is a related stress-induced molecular chaperone protein. All four candidate genes, including GRP78, showed similar VPA concentration-dependent increases in mRNA abundance. Another commonly prescribed mood-stabilizing anticonvulsant, carbamazepine, also increased GRP78 mRNA expression in C6 glioma cells, whereas lithium had no effect at doses up to 2 mM. Immunoblotting revealed that GRP78 protein levels were also increased in C6 glioma cells treated with VPA under the same conditions. Nuclear runoff analysis showed that VPA increased GRP78 gene transcription. Because GRP78 possesses molecular chaperone activity, binds Ca2+ in the endoplasmic reticulum, and protects cells from the deleterious effects of damaged proteins, the present findings suggest that VPA (and possibly carbamazepine) treatment may target one or more of these processes. (+info)
Carbamazepine-induced upregulation of adenosine A1-receptors in astrocyte cultures affects coupling to the phosphoinositol signaling pathway.
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The anticonvulsant and antibipolar drug carbamazepine (CBZ) is known to act as a specific antagonist at adenosine A1-receptors. After a 3-week application of CBZ, A1-receptors are upregulated in the rat brain. We have investigated the consequences of this upregulation for the A1-receptor-mediated signal transduction in primary astrocyte cultures from different regions of the rat brain. CBZ treatment for 10 days had no effect on adenosine A1-receptor mRNA expression in cultures with high basal A1-receptor mRNA levels, but increased A1-receptor mRNA in cultures exhibiting low basal A1-receptor mRNA levels. This upregulation of A1-receptor mRNA was accompanied by an upregulation or induction of A1-receptor-mediated potentiation of PLC activity, a property that was not found in these cultures before CBZ treatment. Thus, CBZ treatment for 10 days induces a new quality of adenosine A1-receptor-mediated signal transduction in cells that express low basal A1-receptor numbers. (+info)
Carbamazepine facilitates effects of GABA on rat hippocampus slices.
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AIM: To study the influence of carbamazepine (Car) on GABA effect in hippocampus. METHODS: Evoked potentials were recorded on pyramidal cells in CA1 after stimulation (0.5 Hz, 50 microseconds) to Schaffer collaterals in rat hippocampal slices (350 microns). RESULTS: Car 0.1 and 0.2 mmol.L-1 did not affect field potentials, whereas Car 0.2 mmol.L-1 plus GABA (0.1-1 mmol.L-1) gave rise to a stronger inhibition on field potentials than that of GABA alone. Bicuculline did not reverse Car facilitation on GABA inhibition on field potentials. (-)-Baclofen was more effective in inhibiting field potentials than GABA. Car 0.2 mmol.L-1 plus (-)-baclofen (1-5 mumol.L-1) brought an inhibition stronger than that of (-)-baclofen alone. CONCLUSION: Car facilitates the effects of GABA on pyramidal cells in hippocampal CA1 region, probably related to GABAB receptors. (+info)
Outcome of pregnancies in epileptic women: a study in Saudi Arabia.
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We studied the outcome of 79 pregnancies in 44 Saudi women who had epilepsy. Their mean age was 28+/-6.5 years and the number of pregnancies studied varied from one to six. Nineteen subjects had generalized seizures, 16 had partial seizures and nine were unclassified. The commonest drug prescribed was carbamazepine and the majority of the women (61%) were on monotherapy. The seizures were controlled in 53 pregnancies (67%). Spontaneous vertex deliveries were the commonest. The indications for intervention by lower segment Caesarean section, forceps or ventouse were foetal distress, pre-eclamptic toxaemia (PET), eclampsia, breech presentation and prolonged labour. The most frequent adverse outcome in the babies was low birth weight (<2.5 kg) in nine pregnancies. The frequency of congenital malformation was 2.5%. Low birth weight was associated with prematurity, PET, congenital malformation and polytherapy. Avoidance of polytherapy appears to be the most feasible intervention in reducing the frequency of low birth-weight children by epileptic mothers. (+info)
Clinical and EEG findings in complex partial status epilepticus with tiagabine.
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A case of complex partial status epilepticus (CPSE) with high dose treatment of tiagabine (TGB) is reported. Seizure aggravation and CPSE developed after stepwise increase of TGB to a dose of 60 mg per day as add-on treatment to carbamazepine (CBZ) 1200 mg/day and vigabatrine (VGB) 1000 mg/day. The EEG during CPSE showed bilateral rhythmic slow activity. Clinical symptoms of CPSE and the EEG normalized after i.v. treatment with clonazepam. The literature and the possible mechanism of this paradoxical phenomenon are discussed. (+info)
Does withdrawal of different antiepileptic drugs have different effects on seizure recurrence? Further results from the MRC Antiepileptic Drug Withdrawal Study.
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One thousand and thirteen patients, in remission of epilepsy for at least 2 years, were randomized to continued therapy or slow withdrawal over 6 months and were followed up for a median period of 5 years. At the time of randomization 83% of patients were receiving monotherapy with carbamazepine (237 patients), phenobarbitone/primidone (72 patients), phenytoin (184 patients) or valproate (228 patients) in low doses, and plasma levels were below the usual optimal range. The most important factor determining seizure recurrence was continued therapy, which was the case for barbiturates, phenytoin and valproate. There was no significant difference for patients taking carbamazepine at randomization, because of a low rate of recurrence in those withdrawing treatment. The difference between carbamazepine and other drugs was not explained by differences in covariate prognostic factors. There was no evidence that withdrawal of phenobarbitone was associated with withdrawal seizures. These data provide unique evidence for the effectiveness of standard antiepileptic drugs as monotherapy. The results for carbamazepine may be open to a number of interpretations. (+info)
Anticonvulsant-induced dyskinesias: a comparison with dyskinesias induced by neuroleptics.
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Anticonvulsants cause dyskinesias more commonly than has been appreciated. Diphenylhydantoin (DPH), carbamazepine, primidone, and phenobarbitone may cause asterixis. DPH, but not other anticonvulsants, may cause orofacial dyskinesias, limb chorea, and dystonia in intoxicated patients. These dyskinesias are similar to those caused by neuroleptic drugs and may be related to dopamine antagonistic properties possessed by DPH. (+info)
Bipolar disorder in old age.
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OBJECTIVE: To review the classification, clinical characteristics, and epidemiology of bipolar disorders in old age with a special focus on neurologic comorbidity, high mortality, and management. QUALITY OF EVIDENCE: Most available data is gleaned from retrospective chart reviews and cohort studies. Treatment recommendations are based on evidence from younger populations and a few anecdotal case reports and series involving elderly people. MAIN MESSAGE: While relatively rare in the community setting, mania in old age frequently leads to hospitalization. It is associated with late-onset neurologic disorders (especially cerebrovascular disease) involving the right hemisphere and orbitofrontal cortex. Prognosis is relatively poor; morbidity and mortality rates are high. Management of bipolarity includes cautious use of mood stabilizers, especially lithium and divalproex. CONCLUSIONS: Mania in old age should trigger a careful assessment of underlying neurologic disease, especially cerebrovascular disease. Close clinical follow up is essential. (+info)