GABA interneurons are the cellular trigger for ketamine’s rapid antidepressant actions
Danielle M. Gerhard, Santosh Pothula, Rong-Jian Liu, Min Wu, Xiao-Yuan Li, Matthew J. Girgenti, Seth R. Taylor, Catharine H. Duman, Eric Delpire, Marina Picciotto, Eric S. Wohleb, Ronald S. Duman
Danielle M. Gerhard, Santosh Pothula, Rong-Jian Liu, Min Wu, Xiao-Yuan Li, Matthew J. Girgenti, Seth R. Taylor, Catharine H. Duman, Eric Delpire, Marina Picciotto, Eric S. Wohleb, Ronald S. Duman
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Research Article Neuroscience

GABA interneurons are the cellular trigger for ketamine’s rapid antidepressant actions

Abstract

A single subanesthetic dose of ketamine, an NMDA receptor (NMDAR) antagonist, produces rapid and sustained antidepressant actions in depressed patients, addressing a major unmet need for the treatment of mood disorders. Ketamine produces a rapid increase in extracellular glutamate and synaptic formation in the prefrontal cortex, but the initial cellular trigger that initiates this increase and ketamine’s behavioral actions has not been identified. To address this question, we used a combination of viral shRNA and conditional mutation to produce cell-specific knockdown or deletion of a key NMDAR subunit, GluN2B, implicated in the actions of ketamine. The results demonstrated that the antidepressant actions of ketamine were blocked by GluN2B-NMDAR knockdown on GABA (Gad1) interneurons, as well as subtypes expressing somatostatin (Sst) or parvalbumin (Pvalb), but not glutamate principle neurons in the medial prefrontal cortex (mPFC). Further analysis of GABA subtypes showed that cell-specific knockdown or deletion of GluN2B in Sst interneurons blocked or occluded the antidepressant actions of ketamine and revealed sex-specific differences that are associated with excitatory postsynaptic currents on mPFC principle neurons. These findings demonstrate that GluN2B-NMDARs on GABA interneurons are the initial cellular trigger for the rapid antidepressant actions of ketamine and show sex-specific adaptive mechanisms to GluN2B modulation.

Authors

Danielle M. Gerhard, Santosh Pothula, Rong-Jian Liu, Min Wu, Xiao-Yuan Li, Matthew J. Girgenti, Seth R. Taylor, Catharine H. Duman, Eric Delpire, Marina Picciotto, Eric S. Wohleb, Ronald S. Duman

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Figure 3

Infusion of AAV2GluN2BshRNA into mPFC of Gad1Cre+, but not Camk2aCre+, male mice occludes the antidepressant effects of ketamine.

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Infusion of AAV2GluN2BshRNA into mPFC of Gad1Cre+, but not Camk2aCre+, m...
(A) Procedure schematic. (B and F) Representative images of AAV2GluN2BshRNA-mediated expression and recombination in the mPFC of (B) WT-Camk2aCre–, Camk2aCre+, (F) WT-Gad1Cre–/AAV, and Gad1Cre+/AAV male mice. Scale bars: 50 μm and 20 μm (insets). (C) In Camk2aCre+/AAV mice, there was no effect of GluN2B knockdown on baseline immobility (preswim) or time spent in center and distance traveled in the open field test (OFT; n = 18–21 per group). (D) WT-Camk2aCre–/AAV-ket and Camk2aCre+/AAV-ket mice showed significantly reduced immobility in the forced swim test (FST) compared with saline controls (n = 12–14 per group, treatment: F1,34 = 18.18, P = 0.0002). (E) WT-Camk2aCre-/AAV-ket and Camk2aCre+/AAV-ket mice showed significantly reduced latency to feed in the novelty-suppressed feeding test (NSFT; n = 9–11 per group, treatment: F1,36 = 19.89, P < 0.0001, genotype: F1,36 = 4.186, P = 0.0481). No significant differences were found in home cage feeding. (G) There was a significant reduction in preswim immobility in Gad1Cre+/AAV mice, but no effect on time spent in center and distance traveled in the OFT (n = 15–21 per group, t34 = 2.226, P = 0.0327). (H) Only WT-Gad1Cre-/AAV-ket mice showed significantly reduced immobility in FST compared with their saline controls (n = 7–11 per group, genotype: F1,32 = 8.662, P = 0.006, treatment: F1,32 = 9.313, P = 0.0045 genotype times treatment: F1,32 = 10.04, P = 0.0034). (I) Only WT-Gad1Cre-/AAV-ket mice showed significantly reduced latency to feed in the NSFT (n = 7–11 per group, genotype times treatment: F1,32 = 4.716, P = 0.0374). Preswim and OFT: unpaired 2-tailed t test. FST and NSFT: 2-way ANOVA with Tukey’s multiple-comparisons test. *P < 0.05; **P < 0.01; ***P < 0.001. All data are represented as mean ± SEM. Abbreviations: sal, saline; ket, ketamine.