Inhibition of Glutamate Release, but Not of Glutamine Recycling to Glutamate, Is Involved in Delaying the Onset of Initial Lithium-Pilocarpine-Induced Seizures in Young Rats by a Non-Convulsive MSO Dose
INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES(2021)
摘要
Initial seizures observed in young rats during the 60 min after administration of pilocarpine (Pilo) were delayed and attenuated by pretreatment with a non-convulsive dose of methionine sulfoximine (MSO). We hypothesized that the effect of MSO results from a) glutamine synthetase block-mediated inhibition of conversion of Glu/Gln precursors to neurotransmitter Glu, and/or from b) altered synaptic Glu release. Pilo was administered 60 min prior to sacrifice, MSO at 75 mg/kg, i.p., 2.5 h earlier. [1,2-C-13]acetate and [U-C-13]glucose were i.p.-injected either together with Pilo (short period) or 15 min before sacrifice (long period). Their conversion to Glu and Gln in the hippocampus and entorhinal cortex was followed using [C-13] gas chromatography-mass spectrometry. Release of in vitro loaded Glu surrogate, [H-3]d-Asp from ex vivo brain slices was monitored in continuously collected superfusates. [H-3]d-Asp uptake was tested in freshly isolated brain slices. At no time point nor brain region did MSO modify incorporation of [C-13] to Glu or Gln in Pilo-treated rats. MSO pretreatment decreased by ~37% high potassium-induced [H-3]d-Asp release, but did not affect [H-3]d-Asp uptake. The results indicate that MSO at a non-convulsive dose delays the initial Pilo-induced seizures by interfering with synaptic Glu-release but not with neurotransmitter Glu recycling.
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关键词
epilepsy, glutamatergic transmission, glutamine synthesis, methionine sulfoximine, metabolomics
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