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We report the effects of i.p. administration of sodium valproate (VPA) on extracellular concentrations of various amino acids in the rat ventral hippocampus studied using in vivo microdialysis, followed by HPLC with fluorometric detection. At the doses used (100, 200 and 400 mg/kg), VPA had no effect on extracellular aspartate, glutamine and taurine, whilst(More)
Previous work has shown that N-methyl-D-aspartate (NMDA) receptor activation decreases 5-hydroxytryptamine (5-HT) release in the hippocampus of freely moving rats. Given the association between NMDA receptor function and nitric oxide (NO) production with the regulation of 5-HT release in other brain regions, we have studied this in rat hippocampus. NMDA(More)
We have studied the effects of treatment with the anticonvulsants lamotrigine (LTG), phenytoin (PHN) and carbamazepine (CBZ) on basal and stimulated extracellular aspartate (ASP), glutamate (GLU), taurine (TAU), GABA, 5-hydroxytryptamine (5-HT) and dopamine (DA) in the hippocampus of freely moving rats using microdialysis. All of the drugs investigated have(More)
The effects of sodium valproate (VPA; 100, 200, and 400 mg/kg, i.p.) on ventral hippocampal and anterior caudate putamen extracellular levels of dopamine (DA) and 5-hydroxytryptamine (5-HT) were examined using in vivo microdialysis. VPA induced dose-related increases in dialysate DA, 3,4-dihydroxyphenylacetic acid, and 5-HT in the ventral hippocampus.(More)
The non-competitive N-methyl-D-aspartate receptor antagonist MK-801 was observed to have regionally specific effects on the extracellular concentration of dopamine and its metabolites. In rat anterior striatum, MK-801 transiently decreased extracellular dopamine, in spite of inducing intense circling behaviour which is generally associated with an increase(More)
The antiepileptic drug lamotrigine (LTG) is a relatively novel anticonvulsant frequently used in polytherapy and increasingly in monotherapy. LTG is believed to act by reducing excitatory glutamate (GLU) release due to an inhibition of Na(+) channels. In the present study, we have investigated the effects of acute and chronic (up to 21 days) treatment with(More)
The antiepileptic drugs sodium valproate (VPA) and lamotrigine (LTG) are increasingly used in combination in patients in whom monotherapy has failed to control seizures. Although these drugs are known to interact pharmacokinetically, several authors have proposed a pharmacodynamic interaction between the two. In order to investigate this we have studied the(More)
Two "suicide" inhibitors of GABA-aminotransferase which are known to raise the concentration of GABA in vivo and to have anti-convulsant properties, have been compared for the extent to which they produce micro-vacuoles in the brains of rats. The compounds gamma-vinyl-GABA (Vigabatrin) and ethanolamine-O-sulphate were administered orally for six months to(More)
Strong evidence implicates glutamate as an excitatory neurotransmitter in the central nervous system. In the present study we have investigated the effects of different concentrations of the excitatory amino acid agonist alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid on release of 5-hydroxytryptamine in rat hippocampus using in vivo microdialysis.(More)
The effects of infusing N-methyl-D-aspartate (NMDA), and the specific NMDA receptor antagonist D-2-amino-5-phosphono-propionic acid (D-AP5) into rat hippocampus and striatum on extracellular dopamine (DA) and its metabolites dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA) were studied using intracerebral microdialysis. In striatum NMDA(More)