Enantiomers of 2-methylglutamate and 2-methylglutamine selectively impact mouse brain metabolism and behavior

Sci Rep. 2021 Apr 14;11(1):8138. doi: 10.1038/s41598-021-87569-1.

Abstract

Imbalance of excitatory and inhibitory neurotransmission is implicated in a wide range of psychiatric and neurologic disorders. Here we tested the hypothesis that insertion of a methyl group on the stereogenic alpha carbon of L-Glu or L-Gln would impact the γ-aminobutyric acid (GABA) shunt and the glutamate-glutamine cycle. (S)-2-methylglutamate, or (S)-2MeGlu, was efficiently transported into brain and synaptosomes where it was released by membrane depolarization in a manner equivalent to endogenous L-Glu. (R)-2MeGlu was transported less efficiently into brain and synaptosomes but was not released by membrane depolarization. Each enantiomer of 2MeGlu had limited activity across a panel of over 30 glutamate and GABA receptors. While neither enantiomer of 2MeGlu was metabolized along the GABA shunt, (S)-2MeGlu was selectively converted to (S)-2-methylglutamine, or (S)-2MeGln, which was subsequently slowly hydrolyzed back to (S)-2MeGlu in brain. rac-2MeGln was also transported into brain, with similar efficiency as (S)-2MeGlu. A battery of behavioral tests in young adult wild type mice showed safety with up to single 900 mg/kg dose of (R)-2MeGlu, (S)-2MeGlu, or rac-2MeGln, suppressed locomotor activity with single ≥ 100 mg/kg dose of (R)-2MeGlu or (S)-2MeGlu. No effect on anxiety or hippocampus-dependent learning was evident. Enantiomers of 2MeGlu and 2MeGln show promise as potential pharmacologic agents and imaging probes for cells that produce or transport L-Gln.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Behavior, Animal / drug effects
  • Brain / metabolism*
  • Chromatography, Liquid
  • Dose-Response Relationship, Drug
  • Female
  • Glutamates / administration & dosage*
  • Glutamates / chemistry
  • Glutamates / pharmacokinetics
  • Glutamine / administration & dosage*
  • Glutamine / chemistry
  • Glutamine / pharmacokinetics
  • Male
  • Mice
  • Primary Cell Culture
  • Stereoisomerism
  • Synaptosomes / metabolism*
  • Tandem Mass Spectrometry
  • gamma-Aminobutyric Acid / metabolism

Substances

  • Glutamates
  • Glutamine
  • 2-methylglutamic acid
  • gamma-Aminobutyric Acid