2. Academic Validation
  3. Orexin 2 receptor stimulation enhances resilience, while orexin 2 inhibition promotes susceptibility, to social stress, anxiety and depression

Orexin 2 receptor stimulation enhances resilience, while orexin 2 inhibition promotes susceptibility, to social stress, anxiety and depression

  • Neuropharmacology. 2018 Dec;143:79-94. doi: 10.1016/j.neuropharm.2018.09.016.
Clarissa D Staton 1,  Jazmine D W Yaeger 1,  Delan Khalid 2,  Fadi Haroun 3,  Belissa S Fernandez 4,  Jessica S Fernandez 4,  Bali K Summers 5,  Tangi R Summers 1,  Monica Sathyanesan 6,  Samuel S Newton 6,  Cliff H Summers 7
Affiliations

Affiliations

  • 1 Department of Biology, University of South Dakota, Vermillion, SD 57069, USA; Neuroscience Group, Division of Basic Biomedical Sciences, Sanford School of Medicine, University of South Dakota, Vermillion, SD 57069, USA; Veterans Affairs Research Service, Sioux Falls VA Health Care System, Sioux Falls, SD 57105, USA.
  • 2 Department of Biology, University of South Dakota, Vermillion, SD 57069, USA; Department of Biology, University of Massachusetts, Boston, 100William T. Morrissey Blvd, Boston, MA 02125, USA.
  • 3 Department of Biology, University of South Dakota, Vermillion, SD 57069, USA; Department of Biology, University of Utah, 257 South 1400 East, Rm. 201 Salt Lake City, UT 84112-0840, USA.
  • 4 Department of Biology, University of South Dakota, Vermillion, SD 57069, USA.
  • 5 Vermillion High School, 1001 E Main Street, Vermillion, SD 57069, USA; Department of Chemistry, Colorado State University, 1301 Center Ave Campus Delivery 1872, Ft. Collins, CO 80523-1872, USA.
  • 6 Neuroscience Group, Division of Basic Biomedical Sciences, Sanford School of Medicine, University of South Dakota, Vermillion, SD 57069, USA.
  • 7 Department of Biology, University of South Dakota, Vermillion, SD 57069, USA; Neuroscience Group, Division of Basic Biomedical Sciences, Sanford School of Medicine, University of South Dakota, Vermillion, SD 57069, USA; Veterans Affairs Research Service, Sioux Falls VA Health Care System, Sioux Falls, SD 57105, USA. Electronic address: cliff@usd.edu.
PMID: 30240784 DOI: 10.1016/j.neuropharm.2018.09.016
Abstract

Knockdown of orexin/hypocretin 2 receptor (Orx2) in the basolateral amygdala (BLA) affects anxious and depressive behavior. We use a new behavioral paradigm, the Stress Alternatives Model (SAM), designed to improve translational impact. The SAM induces social stress in adult male mice by aggression from larger mice, allowing for adaptive decision-making regarding escape. In this model, mice remain (Stay) in the oval SAM arena or escape from social aggression (Escape) via routes only large enough for the smaller mouse. We hypothesized intracerebroventricular (icv) stimulation of Orx2 receptors would be anxiolytic and antidepressive in SAM-related social behavior and the Social Interaction/Preference (SIP) test. Conversely, we predicted that icv antagonism of Orx2 receptors would promote anxious and depressive behavior in these same tests. Anxious behaviors such as freezing (both cued and conflict) and startle are exhibited more often in Stay compared with Escape phenotype mice. Time spent attentive to the escape route is more frequent in Escape mice. In Stay mice, stimulation of Orx2 receptors reduces fear conditioning, conflict freezing and startle, and promotes greater attention to the escape hole. This anxiolysis was accompanied by activation of a cluster of inhibitory neurons in the amygdala. A small percentage of those Stay mice also begin escaping; whereas Escape is reversed by the Orx2 antagonist. Escape mice were also Resilient, and Stay mice Susceptible to stress (SIP), with both conditions reversed by Orx2 antagonism or stimulation respectively. Together, these results suggest that the Orx2 receptor may be a useful potential target for anxiolytic or antidepressive therapeutics.

Keywords

Anxiety; Defeat; Depression; Fear conditioning; Freezing; Hypocretin; MK-1064, 5″-chloro-N-[(5,6-dimethoxy-2-pyridinyl)methyl]-[2,2':5′,3″-terpyridine]-3′-carboxamide - an Orx(2) antagonist; Resilience; Startle; Stress Alternatives Model; Susceptibility; [Ala11, d-Leu15]–Orx(B), a modified Orx(B) peptide used as an Orx(2) receptor agonist.

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