Baseline Levels of Neuroinflammation in the Grin2a Knockout Mouse Open Access

Abstract

Epilepsy is a common neurological disease characterized by recurrent seizures. Genetic loss-of-function variants of GRIN2A are causative for epilepsy.  GRIN2A encodes the GluN2A subunit of the NMDA receptor, a major glutamatergic excitatory receptor in the brain.  A growing body of work has implicated neuroinflammation in the disease course of epilepsy, and deletion of the GluN2A subunit has been associated with neuroinflammation.  In humans, anti-inflammatory agents are beneficial in GRIN2A-associated epilepsy; these patients experience normalized EEGs, improved language, and improved sleep architecture when administered anti-inflammatory therapies. However, no work to date has measured the effect of this receptor on baseline, non-epileptic neuroinflammation levels. Microglia and astrocytes are brain-derived glial cells that undergo morphological transformation during neuroinflammation.  Using Grin2a knockout (KO) mice lacking the GluN2A subunit, neuroinflammation was measured via immunohistochemical staining of microglia and astrocytes using anti- IBA1 and GFAP antibodies, respectively, in both adolescent and adult mice. A slight, 1.36-fold increase in fluorescent area covered by GFAP staining was found in the CA1 radiatum of adolescent mice lacking the GluN2A subunit. No difference between genotypes was observed in GFAP staining in adults, nor was a difference found between genotypes for adolescent and adult IBA1 staining. These findings indicate that during development, there is a transient increase in astrocyte reactivity in Grin2a KO mice that resolves by adulthood.

Table of Contents

Introduction……….1

Epilepsy……….1

            Glutamate and Glutamate Receptors……….1

            NMDA Receptor Subunit Expression in Brain……….2

            GRIN2A Variants……….4

            GRIN2A-Associated Epilepsy……….6

            Neuroinflammation in Epilepsy……….8

            GluN2A and Neuroinflammation……….9

            Microglia and Astrocytes in Neuroinflammation……….13

            Rationale……….15

            Hypothesis……….16

Materials and Methods……….16

Results……….20

Discussion……….28

            Result and Primary Conclusion……….28

            Relation to Previous Works……….28

            Methodological Considerations and Alternative Explanations……….29

            Future Directions……….32

References……….36

 

About this Honors Thesis

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School	Emory College
Department	Chemistry
Degree	B.S.
Submission	Honors Thesis
Language	English
Research Field	Chemistry, Biochemistry Biology, Molecular
Keyword	neuroinflammation glun2a grin2a 2a nmda
Committee Chair / Thesis Advisor	Dr. Nicholas H. Varvel, Emory University
Committee Members	Dr. Asheebo Rojas, Emory University Dr. Steven A. Sloan, Emory University Dr. Stephen F. Traynelis, Emory University Dr. Dennis C. Liotta, Emory University

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Supplemental Files

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	Supplementary Data Table S1 (Data of Known GRIN2A Variants)	2021-04-09 16:34:31 -0400	Press to Select an action Download