Cell-type specific deletion of GABA(A)α1 in corticotropin-releasing factor-containing neurons enhances anxiety and disrupts fear extinction

Abstract

Corticotropin-releasing factor (CRF) is critical for the endocrine, autonomic, and behavioral responses to stressors, and it has been shown to modulate fear and anxiety. The CRF receptor is widely expressed across a variety of cell types, impeding progress toward understanding the contribution of specific CRF-containing neurons to fear dysregulation. We used a unique CRF-Cre driver transgenic mouse line to remove floxed GABA(A)α1 subunits specifically from CRF neurons [CRF-GABA(A)α1 KO]. This process resulted in mice with decreased GABA(A)α1 expression only in CRF neurons and increased CRF mRNA within the amygdala, bed nucleus of the stria terminalis (BNST) and paraventricular nucleus of the hypothalamus. These mice show normal locomotor and pain responses and no difference in depressive-like behavior or Pavlovian fear conditioning. However, CRF-GABA(A)α1 KO increased anxiety-like behavior and impaired extinction of conditioned fear, coincident with an increase in plasma corticosterone concentration. These behavioral impairments were rescued with systemic or BNST infusion of the CRF antagonist R121919. Infusion of Zolpidem, a GABA(A)α1-preferring benzodiazepine-site agonist, into the BNST of the CRF-GABA(A)α1 KO was ineffective at decreasing anxiety. Electrophysiological findings suggest a disruption in inhibitory current may play a role in these changes. These data indicate that disturbance of CRF containing GABA(A)α1 neurons causes increased anxiety and impaired fear extinction, both of which are symptoms diagnostic for anxiety disorders, such as posttraumatic stress disorder.central amygdala | plasticity | HPA axis | short term synaptic depression | knockout T he neuropeptide corticotrophin-releasing factor (CRF) is involved in initiation of the endocrine, autonomic, and behavioral responses to stressors and its dysfunction is implicated in a variety of mood and anxiety disorders (1). Large populations of CRF-containing neurons are located within brain areas crucial for fear and anxiety, including the central amygdala (CeA), bed nucleus of the stria terminalis (BNST), and paraventricular nucleus of the hypothalamus (PVN). Although site-specific and conditional knockout approaches are increasingly being used (2, 3), the broad expression of CRF receptors and the varied cell types in which the CRF peptide is produced (4, 5) make it challenging to identify region and cell-type specific influences of CRF. One way to manipulate specific subpopulations of CRF neurons is to use mice with the Cre recombinase gene driven by the CRF promoter to allow different subgroups of CRFergic cells to be manipulated.The interaction between CRF and GABA activity in brain structures important for fear and anxiety has been identified as a potential mechanism underlying anxiety disorders (6). CRF administration increases GABA release within the amygdala (7, 8) and causes deficits in GABA(A) receptor-mediated inhibitory transmission (9). Lifelong CRF overexpression leads to changes in GABA receptor subtype expression and sensitivity (1...

CRH Engagement of the Locus Coeruleus Noradrenergic System Mediates Stress-Induced Anxiety

“…of endogenous CRH action on CRHR1 receptors is sufficient to prevent stress-induced anxiety (Fig. 6A–D) (Gafford et al, 2012; Heinrichs et al, 1994). We next determined whether the action of CRH locally within the LC is responsible for CRH-dependent anxiety-like behavior.…”

“…Anatomical data support this notion using tract tracing studies and electron microscopy to suggest that CRH-containing amygdalar monosynaptic projections from the CeA terminate in the LC (Reyes et al, 2008). Given the importance of CRH in stress-induced behavioral responses such as dysphoria, anxiety, and aversion (Bruchas et al, 2009; Francis et al, 1999; Gafford et al, 2012; Heinrichs et al, 1994; Koob, 1999; Land et al, 2008), these projections are situated to significantly impact LC neuronal activity. However, the functional consequences of these inputs remain unresolved.…”

Amygdala-Dependent Fear Memory Consolidation via miR-34a and Notch Signaling

“…Animals were recorded while exploring the plus maze for 5 minutes in a dimly lit room. The amount of time spent in the closed versus open arms is viewed as a measure of anxiety-like behavior (Gafford et al, 2012). The recording and analysis were both carried out using Limelight Software (Actimetrics).…”

The Proinflammatory Cytokine Interleukin 18 Regulates Feeding by Acting on the Bed Nucleus of the Stria Terminalis

“…The alBST contains the oval (ovBST) and the juxtacapsular nucleus (jcBST) and is interconnected with regions that subserve stress and reward, including the amygdala, lateral hypothalamus (LH), ventral tegmental area, and NAc (Choi and Lovinger, 1997;Aston-Jones and Druhan, 1999;Georges and Aston-Jones, 2001;Georges and Aston-Jones, 2002;Funk et al, 2006;Sahuque et al, 2006;Shepard et al, 2006;Lee et al, 2008;Jalabert et al, 2009;Gafford et al, 2012;Kim et al, 2013;Sink et al, 2013;Micioni Di Bonaventura et al, 2014;Gafford and Ressler, 2015). The vast majority (70%-90%) of adBST neurons are composed of medium-sized spiny GABAergic neurons (McDonald, 1983;Sun and Cassell, 1993;.…”