Glutamate dehydrogenase-deficient mice display schizophrenia-like behavioral abnormalities and CA1-specific hippocampal dysfunction

Sharon S. Lander, Usman Khan, Nicole Lewandowski, Darpan Chakraborty, Frank A. Provenzano, Susana Mingote, Sergiy Chornyy, Francesca Frigerio, Pierre Maechler, Hanoch Kaphzan, Scott A. Small, Stephen Rayport, Inna Gaisler-Salomon

Research output: Contribution to journalArticlepeer-review

Abstract

Brain imaging has revealed that the CA1 subregion of the hippocampus is hyperactive in prodromal and diagnosed patients with schizophrenia (SCZ), and that glutamate is a driver of this hyperactivity. Strikingly, mice deficient in the glutamate synthetic enzyme glutaminase have CA1 hypoactivity and a SCZ-resilience profile, implicating glutamate-metabolizing enzymes. To address this further, we examined mice with a brain-wide deficit in the glutamate-metabolizing enzyme glutamate dehydrogenase (GDH), encoded by Glud1, which should lead to glutamate excess due to reduced glutamate metabolism in astrocytes. We found that Glud1-deficient mice have behavioral abnormalities in the 3 SCZ symptom domains, with increased baseline and amphetamine-induced hyperlocomotion as a positive symptom proxy, nest building and social preference as a negative symptom proxy, and reversal/extradimensional set shifting in the water T-maze and contextual fear conditioning as a cognitive symptom proxy. Neuroimaging of cerebral blood volume revealed hippocampal hyperactivity in CA1, which was associated with volume reduction. Parameters of hippocampal synaptic function revealed excess glutamate release and an elevated excitatory/ inhibitory balance in CA1. Finally, in a direct clinical correlation using imaging-guided microarray, we found a significant SCZ-associated postmortem reduction in GLUD1 expression in CA1. These findings advance GLUD1 deficiency as a driver of excess hippocampal excitatory transmission and SCZ symptoms, and identify GDH as a target for glutamate modulation pharmacotherapy for SCZ. More broadly, these findings point to the likely involvement of alterations in glutamate metabolism in the pathophysiology of SCZ.

Original languageEnglish
Pages (from-to)127-137
Number of pages11
JournalSchizophrenia Bulletin
Volume45
Issue number1
DOIs
StatePublished - Jan 2019

Bibliographical note

Funding Information:
This study was supported by an Israel Science Foundation grant 484/10 to IGS, a US-Israel Binational Science Foundation grant 2009301 (to Drs Gaisler-Salomon, Rayport, and Small), Israel Science Foundation grant 287/15 (to Dr. Kaphzan), a Columbia University RISE award (to S.R.), and National Institutes of Health R01 MH093398 (to Dr. Small).

Publisher Copyright:
© 2018 The Author(s).

Keywords

  • Amphetamine-induced hyperactivity
  • Behavior
  • CA1
  • CBV
  • Mouse model
  • fMRI

ASJC Scopus subject areas

  • Psychiatry and Mental health

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