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eNeuro. 2018 Mar 6;5(1). pii: ENEURO.0025-18.2018. doi: 10.1523/ENEURO.0025-18.2018. eCollection 2018 Jan-Feb.

Inhibition of a Descending Prefrontal Circuit Prevents Ketamine-Induced Stress Resilience in Females.

Author information

1
Department of Psychology and Neuroscience and the Center for Neuroscience, University of Colorado Boulder, Boulder, CO 80309.
2
Institute for Behavioral Genetics, University of Colorado Boulder, Boulder, CO 80309.
3
Department of Neuroscience, University of Copenhagen, Copenhagen, 1165 Denmark.
4
McGovern Institute for Brain Research, Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139.

Abstract

Stress is a potent etiological factor in the onset of major depressive disorder and posttraumatic stress disorder (PTSD). Therefore, significant efforts have been made to identify factors that produce resilience to the outcomes of a later stressor, in hopes of preventing untoward clinical outcomes. The NMDA receptor antagonist ketamine has recently emerged as a prophylactic capable of preventing neurochemical and behavioral outcomes of a future stressor. Despite promising results of preclinical studies performed in male rats, the effects of proactive ketamine in female rats remains unknown. This is alarming given that stress-related disorders affect females at nearly twice the rate of males. Here we explore the prophylactic effects of ketamine on stress-induced anxiety-like behavior and the neural circuit-level processes that mediate these effects in female rats. Ketamine given one week prior to an uncontrollable stressor (inescapable tailshock; IS) reduced typical stress-induced activation of the serotonergic (5-HT) dorsal raphe nucleus (DRN) and eliminated DRN-dependent juvenile social exploration (JSE) deficits 24 h after the stressor. Proactive ketamine altered prelimbic cortex (PL) neural ensembles so that a later experience with IS now activated these cells, which it ordinarily would not. Ketamine acutely activated a PL to DRN (PL-DRN) circuit and inhibition of this circuit with Designer Receptors Exclusively Activated by Designer Drugs (DREADDs) at the time of IS one week later prevented stress prophylaxis, suggesting that persistent changes in PL-DRN circuit activity are responsible, at least in part, for mediating long-term effects associated with ketamine.

KEYWORDS:

dorsal raphe nucleus; ketamine; prefrontal cortex; resilience; serotonin; stress

PMID:
29516036
PMCID:
PMC5839773
DOI:
10.1523/ENEURO.0025-18.2018
[Indexed for MEDLINE]
Free PMC Article

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