title: Group I and II metabotropic glutamate receptors alter brain cortical metabolic and glutamate/glutamine cycle activity: a 13C NMR spectroscopy and metabolomic study.
abstract: Metabotropic glutamate receptors (mGluR) modulate neuronal function. Here, we tested the effect on metabolism of a range of Group I and II mGluR ligands in Guinea pig brain cortical tissue slices, applying 13C NMR spectroscopy and metabolomic analysis using multivariate statistics. The effects of Group I agonists (S)-3,5-dihydroxyphenylglycine (DHPG) and (RS)-2-chloro-5-hydroxyphenylglycine (CHPG) depended upon concentration and were mostly stimulatory, increasing both net metabolic flux through the Krebs cycle and glutamate/glutamine cycle activity. Only the higher (50 microm) concentrations of CHPG had the opposite effect. The Group I antagonist (RS)-1-aminoindan-1,5-dicarboxylic acid (AIDA), consistent with its neuroprotective role, caused significant decreases in metabolism. With principal components analysis of the metabolic profiles generated by these ligands, the effects could be separated by two principal components. Agonists at Group II mGluR [(2S,2'R,3'R)-2-(2',3'-dicarboxycyclopropyl)glycine (DCG IV) and 2R,4R-4-aminopyrrolidine-2,4-dicarboxylate (APDC)] generally stimulated metabolism, including glutamate/glutamine cycling, although this varied with concentration. The antagonist (2S)-alpha-ethylglutamic acid (EGLU) stimulated astrocyte metabolism with minimal impact on glutamate/glutamine cycling. (RS)-1-Aminophosphoindan-1-carboxylic acid (APICA) decreased metabolism at 5 microm but had a stimulatory effect at 50 microm. All ligand effects were separated from control and from each other using two principal components. The ramifications of these findings are discussed.
authors.affiliation: School of Molecular and Microbial Biosciences, The University of Sydney, New South Wales, Australia. c.rae@mmb.usyd.edu.au
authors.forename: Caroline
authors.initials: C
authors.lastname: Rae
authors.forename: Charbel El-Hajj
authors.initials: Cel-H
authors.lastname: Moussa
authors.forename: Julian L
authors.initials: JL
authors.lastname: Griffin
authors.forename: William A
authors.initials: WA
authors.lastname: Bubb
authors.forename: Trent
authors.initials: T
authors.lastname: Wallis
authors.forename: Vladimir J
authors.initials: VJ
authors.lastname: Balcar
mesh_terms: D000818:Animals; D002247:Carbon Isotopes; D002540:Cerebral Cortex / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D004734:Energy Metabolism / Q000187:drug effects / Q000502:physiology*; D018690:Excitatory Amino Acid Agonists / Q000494:pharmacology; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D018698:Glutamic Acid / Q000378:metabolism*; D005973:Glutamine / Q000378:metabolism*; D006168:Guinea Pigs; D066298:In Vitro Techniques; D008024:Ligands; D009682:Magnetic Resonance Spectroscopy; D015999:Multivariate Analysis; D011188:Potassium / Q000378:metabolism; D025341:Principal Component Analysis; D018094:Receptors, Metabotropic Glutamate / Q000819:agonists / Q000037:antagonists & inhibitors / Q000378:metabolism*
chemical_list: D002247:Carbon Isotopes; D018690:Excitatory Amino Acid Agonists; D018691:Excitatory Amino Acid Antagonists; D008024:Ligands; D018094:Receptors, Metabotropic Glutamate; D005973:Glutamine; D018698:Glutamic Acid; D011188:Potassium