Preprint Article Version 1 Preserved in Portico This version is not peer-reviewed

Mechanistic Insight into the Attenuation of Initial Pilocarpine-Induced Seizures in Young Rats by a Non-Convulsive MSO Dose

Version 1 : Received: 29 July 2021 / Approved: 30 July 2021 / Online: 30 July 2021 (14:26:35 CEST)

How to cite: Pawlik, M.J.; Aldana, B.I.; Belfiori-Carrasco, L.F.; Obara-Michlewska, M.; Popek, M.P.; Czarnecka, A.M.; Albrecht, J. Mechanistic Insight into the Attenuation of Initial Pilocarpine-Induced Seizures in Young Rats by a Non-Convulsive MSO Dose. Preprints 2021, 2021070706 (doi: 10.20944/preprints202107.0706.v1). Pawlik, M.J.; Aldana, B.I.; Belfiori-Carrasco, L.F.; Obara-Michlewska, M.; Popek, M.P.; Czarnecka, A.M.; Albrecht, J. Mechanistic Insight into the Attenuation of Initial Pilocarpine-Induced Seizures in Young Rats by a Non-Convulsive MSO Dose. Preprints 2021, 2021070706 (doi: 10.20944/preprints202107.0706.v1).

Abstract

Pretreatment with non-convulsive dose of methionine sulfoximine (MSO) attenuated lithi-um-pilocarpine-induced (Li-Pilo) seizures in young rats [1]. 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 admin-istered 60 min prior to sacrifice, MSO at 75 mg/kg, i.p., 2.5 h earlier. [1,2-13C]acetate and [U-13C]glucose were i.p.-injected either together with Pilo (onset) or 15 min before sacrifice (final phase). Their conversion to Glu and Gln in hippocampus and entorhinal cortex was followed us-ing [13C] gas chromatography-mass spectrometry. Release of in vitro loaded [3H]D-Asp from ex vi-vo brain slices was measured in continuously collected superfusates. Protein and mRNA expres-sion were measured by Western Blot and real-time PCR techniques, respectively. At no time point nor brain region did MSO modify incorporation of [13C] to Glu or Gln in Pilo-treated rats. MSO pretreatment decreased by ~37% high potassium-induced [3H]D-Asp release and reduced by ~50% the synaptic vesicular Glu transporter VGLUT1 protein, but not mRNA content in the hippo-campus. The results indicate that MSO at non-convulsive dose mitigates the initial Pilo-induced seizures by interfering with synaptic Glu-release but not with neurotransmitter Glu recycling.

Keywords

epilepsy; glutamatergic transmission; glutamine synthesis; methionine sulfoximine; metabolomics

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