The adaptation to chronic stress is highly variable across individuals. Resilience to stress is a complex process recruiting various brain regions and neurotransmitter systems. The aim of this study was to investigate the involvement of endogenous opioid enkephalin (ENK) signaling in the development of stress resilience in mice. The translational model of repeated social defeat (RSD) stress was selected to mimic the unpredictable disruptions of daily life and induce resilience or vulnerability to stress. As in humans, adult C57BL/6J mice demonstrated a great variability in their response to stress under this paradigm. A social interaction (SI) test was used to discriminate between the phenotypes of resilience or vulnerability to stress. After social defeat, the expression levels of ENK mRNA and their delta opioid receptors (DOPr) were quantified in the basolateral amygdala (BLA) and BLA-target areas by hybridization. In this manner, ENK mRNA levels were found to decrease in the BLA and those of DOPr in the ventral hippocampus (HPC) CA1 of vulnerable mice only. Stimulating the DOPr pathway during social defeat by pharmacological treatment with the nonpeptide, selective DOPr agonist SNC80 further induced a resilient phenotype in a majority of stressed animals, with the proportion of resilient ones increasing from 33% to 58% of the total population. Ultrastructural analyses additionally revealed a reduction of oxidative stress markers in the pyramidal cells and interneurons of the ventral HPC CA1 upon SNC80 treatment, thus proposing a mechanism by which ENK-DOPr signaling may prevent the deleterious effects of chronic social stress.
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http://dx.doi.org/10.3389/fnmol.2018.00100 | DOI Listing |
Sci Rep
December 2024
Department of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, USA.
Drug addiction is a multifactorial syndrome in which genetic predispositions and exposure to environmental stressors constitute major risk factors for the early onset, escalation, and relapse of addictive behaviors. While it is well known that stress plays a key role in drug addiction, the genetic factors that make certain individuals particularly sensitive to stress and, thereby, more vulnerable to becoming addicted are unknown. In an effort to test a complex set of gene x environment interactions-specifically gene x chronic stress-here we leveraged a systems genetics resource: BXD recombinant inbred mice (BXD5, BXD8, BXD14, BXD22, BXD29, and BXD32) and their parental mouse lines, C57BL/6J and DBA/2J.
View Article and Find Full Text PDFBr J Pharmacol
December 2024
Laboratory of Pharmacology, Faculty of Pharmaceutical Sciences, Tokyo University of Science, Chiba, Japan.
Background And Purpose: Irritable bowel syndrome (IBS) is a common condition that is challenging to treat, and novel drugs are needed for this condition. Previously, a chronic vicarious social defeat stress (cVSDS) mouse model exhibits IBS-like symptoms. Also agonists of the opioid δ-receptor exert anti-stress effects in rodents with minimal adverse effects.
View Article and Find Full Text PDFBrain Behav Immun Health
February 2025
Department of Neuroscience, The Ohio State University Wexner Medical Center, USA.
Chronic stress increases the incidence of psychiatric disorders including anxiety, depression, and posttraumatic stress disorder. Repeated Social Defeat (RSD) in mice recapitulates several key physiological, immune, and behavioral changes evident after chronic stress in humans. For instance, neurons in the prefrontal cortex, amygdala, and hippocampus are involved in the interpretation of and response to fear and threatful stimuli after RSD.
View Article and Find Full Text PDFGlia
December 2024
Molecular and Cellular Pharmacology Program, Stony Brook, New York, USA.
Chronic stress is a major contributor to the development of major depressive disorder, one of the leading causes of disability worldwide. Using a model of repeated social defeat stress in mice, we and others have reported that neuroinflammation plays a dynamic role in the development of behavioral deficits consistent with social avoidance and impaired reward responses. Animals susceptible to the model also exhibit hypomyelination in the medial prefrontal cortex, indicative of changes in the differentiation pathway of cells of the oligodendroglial lineage (OLN).
View Article and Find Full Text PDFBrain Behav
December 2024
Neuroscience Institute, Georgia State University, Atlanta, Georgia, USA.
Purpose: Perineuronal nets (PNNs) are extracellular matrix proteoglycans surrounding neurons and glia. It has been suggested that PNNs are involved in the pathophysiology of multiple CNS illnesses, including stress-related neuropsychiatric disorders like schizophrenia, major depressive disorder, and anxiety disorders.
Method: Before examining the putative role of PNNs in stress-related responses, we described for the first time the anatomical distribution in Syrian hamsters (Mesocricetus auratus), an excellent model organism for studying social stress and circadian rhythms.
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