In situ metabolite and lipid analysis of GluN2D−/− and wild-type mice after ischemic stroke using MALDI MSI

• Published in: Analytical and bioanalytical chemistry 2020-09, Vol.412 (24), p.6275-6285
• Main Authors: Andrews, William T., Donahue, Deborah, Holmes, Adam, Balsara, Rashna, Castellino, Francis J., Hummon, Amanda B.
• Format: Article
• Language: English
• Subjects: Analytical Chemistry; Animal tissues; Animals; Apoptosis; Biochemistry; Brain; Brain - metabolism; Calcium; Cardiolipin; Cerebral blood flow; Characterization and Evaluation of Materials; Chemistry; Chemistry and Materials Science; Excitotoxicity; Fatty acids; Female Role Models in Analytical Chemistry; Food Science; Gene Deletion; Glutamate receptors; Glutamic acid receptors (ionotropic); Humans; Ions; Ischemia; Ischemic Stroke - genetics; Ischemic Stroke - metabolism; Laboratory Medicine; Lipid Metabolism; Lipids; Lipids - analysis; Male; Mass spectrometry; Mass spectroscopy; Metabolites; Metabolome; Mice, Inbred C57BL; Mice, Knockout; Monitoring/Environmental Analysis; Mouse devices; N-Methyl-D-aspartic acid receptors; Neuroimaging; Neuroprotection; Occlusion; Receptors; Receptors, N-Methyl-D-Aspartate - genetics; Receptors, N-Methyl-D-Aspartate - metabolism; Research Paper; Scientific imaging; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; Spectroscopy; Stroke; Vitamin D
• ISSN: 1618-2642; 1618-2650
• DOI: 10.1007/s00216-020-02477-z

The N -methyl-D-aspartate (NMDA) receptor is a crucial mediator of pathological glutamate-driven excitotoxicity and subsequent neuronal death in acute ischemic stroke. Although the roles of the NMDAR’s composite GluN2A-C subunits have been investigated in this phenomenon, the relative importance of the GluN2D subunit has yet to be evaluated. Herein, GluN2D −/− mice were studied in a model of ischemic stroke using MALDI FT-ICR mass spectrometry imaging to investigate the role of the GluN2D subunit of the NMDA receptor in brain ischemia. GluN2D −/− mice underwent middle cerebral artery occlusion (MCAO) and brain tissue was subsequently harvested, frozen, and cryosectioned. Tissue sections were analyzed via MALDI FT-ICR mass spectrometry imaging. MALDI analyses revealed increases in several calcium-related species, namely vitamin D metabolites, LysoPC, and several PS species, in wild-type mouse brain tissue when compared to wild type. In addition, GluN2D −/− mice also displayed an increase in PC, as well as a decrease in DG, suggesting reduced free fatty acid release from brain ischemia. These trends indicate that GluN2D −/− mice show enhanced rates of neurorecovery and neuroprotection from ischemic strokes compared to wild-type mice. The cause of neuroprotection may be the result of an increase in PGP in knockout mice, contributing to greater cardiolipin synthesis and decreased sensitivity to apoptotic signals. Graphical abstract