A Synergistic Mindsets Intervention Protects Adolescents from Social Stress

Social stress poses a major threat to adolescent health via its effects on internalizing symptoms, such as anxiety and depression. Available interventions to help adolescents improve their stress responses, however, have not been effective in rigorous evaluation studies, or they have been difficult to administer widely. Here we show that replicable improvements in adolescent stress responses can be achieved with a short (~30-minute), scalable synergistic mindsets intervention. This intervention, which is a self-administered online training module, targets both growth mindsets (the idea that people's intelligence can be developed in response to challenge) and stress-can-be-enhancing mindsets (the idea that people's stress responses can be fuel for optimal performance). Its goal is to promote positive engagement with stressful events (e.g., learning from failure on a quiz or a conflict with a peer) and to encourage adolescents to use their responses to stressful events and even their bodily symptoms (e.g. racing heart, sweaty palms, butterflies in their stomach) to their advantage. In five double-blind, randomized, controlled trials (total N = 4,091 adolescents), the new synergistic mindsets intervention improved stress-related cognitions (Studies 1-2), cardiovascular reactivity (Study 3), daily internalizing symptoms and cortisol levels (Study 4), and generalized anxiety symptoms during the 2020 COVID-19 lockdowns (Study 5). Effects on downstream outcomes (in Studies 3-5) were stronger among individuals who, at baseline, held the two negative mindsets targeted by the intervention, providing evidence for the proposed mechanisms. Confidence in this conclusion comes from a conservative, Bayesian machine-learning method for detecting heterogeneity.

The Role of Social Stress in the Development of Inhibitory Control Deficit: A Systematic Review in Preclinical Models

Inhibitory control deficit and impulsivity and compulsivity behaviours are present in different psychopathological disorders such as addiction, obsessive-compulsive disorders and schizophrenia, among others. Social relationships in humans and animals are governed by social organization rules, which modulate inhibitory control and coping strategies against stress. Social stress is associated with compulsive alcohol and drug use, pointing towards a determining factor in an increased vulnerability to inhibitory control deficit. The goal of the present review is to assess the implication of social stress and dominance on the vulnerability to develop impulsive and/or compulsive spectrum disorders, with the aid of the information provided by animal models. A systematic search strategy was carried out on the PubMed and Web of Science databases, and the most relevant information was structured in the text and tables. A total of 34 studies were recruited in the qualitative synthesis. The results show the role of social stress and dominance in increased drug and alcohol use, aggressive and impulsive behaviour. Moreover, the revised studies support the role of Dopaminergic (DA) activity and the alterations in the dopaminergic D1/D2 receptors as key factors in the development of inhibitory control deficit by social stress.

Early Life Exposure to Food Contaminants and Social Stress as Risk Factor for Metabolic Disorders Occurrence?-An Overview

The global prevalence of obesity has been increasing in recent years and is now the major public health challenge worldwide. While the risks of developing metabolic disorders (MD) including obesity and type 2 diabetes (T2D) have been historically thought to be essentially driven by increased caloric intake and lack of exercise, this is insufficient to account for the observed changes in disease trends. Based on human epidemiological and pre-clinical experimental studies, this overview questioned the role of non-nutritional components as contributors to the epidemic of MD with a special emphasis on food contaminants and social stress. This overview examines the impact of early life adverse events (ELAE) focusing on exposures to food contaminants or social stress on weight gain and T2D occurrence in the offspring and explores potential mechanisms leading to MD in adulthood. Indeed, summing up data on both ELAE models in parallel allowed us to identify common patterns that appear worthwhile to study in MD etiology. This overview provides some evidence of a link between ELAE-induced intestinal barrier disruption, inflammation, epigenetic modifications, and the occurrence of MD. This overview sums up evidence that MD could have developmental origins and that ELAE are risk factors for MD at adulthood independently of nutritional status.

Mild-to-moderate schizotypal traits relate to physiological arousal from social stress

Schizotypy denotes psychosis-like experiences, such as perceptual aberration, magical ideation, and social anxiety. Altered physiological arousal from social stress is found in people with high schizotypal traits. Two experiments aimed to determine the relationship of schizotypy to physiological arousal from social stress. Experiment 1 tested the hypotheses that heart rate from social stress would be greater in high, than mild-to-moderate, schizotypal traits, and disorganized schizotypy would explain this effect because of distress from disorganisation. Experiment 1 tested social stress in 16 participants with high schizotypal traits and 10 participants with mild-to-moderate schizotypal traits. The social stress test consisted of a public speech and an informal discussion with strangers. The high schizotypal group had a higher heart rate than the mild-to-moderate schizotypal group during the informal discussion with strangers, but not during the public speech. Disorganized schizotypy accounted for this group difference. Experiment 2 tested the hypothesis that mild-to-moderate schizotypal traits would have a linear relationship with physiological arousal from social stress. Experiment 2 tested 24 participants with mild-to-moderate schizotypal traits performing the abovementioned social stress test while their heart rate and skin conductance responses were measured. Mild-to-moderate schizotypal traits had a linear relationship with physiological arousal during the discussion with strangers. Distress in disorganized schizotypy may explain the heightened arousal from close social interaction with strangers in high schizotypy than mild-to-moderate schizotypy. Mild-to-moderate schizotypal traits may have a linear relationship with HR during close social interaction because of difficulty with acclimatizing to the social interaction.

Salivary Proteome Changes in Response to Acute Psychological Stress Due to an Oral Exam Simulation in University Students: Effect of an Olfactory Stimulus

The autonomic nervous system (ANS) plays a crucial role both in acute and chronic psychological stress eliciting changes in many local and systemic physiological and biochemical processes. Salivary secretion is also regulated by ANS. In this study, we explored salivary proteome changes produced in thirty-eight University students by a test stress, which simulated an oral exam. Students underwent a relaxation phase followed by the stress test during which an electrocardiogram was recorded. To evaluate the effect of an olfactory stimulus, half of the students were exposed to a pleasant odor diffused in the room throughout the whole session. Saliva samples were collected after the relaxation phase (T0) and the stress test (T1). State anxiety was also evaluated at T0 and T1. Salivary proteins were separated by two-dimensional electrophoresis, and patterns at different times were compared. Spots differentially expressed were trypsin digested and identified by mass spectrometry. Western blot analysis was used to validate proteomic results. Anxiety scores and heart rate changes indicated that the fake exam induced anxiety. Significant changes of α-amylase, polymeric immunoglobulin receptor (PIGR), and immunoglobulin α chain (IGHA) secretion were observed after the stress test was performed in the two conditions. Moreover, the presence of pleasant odor reduced the acute social stress affecting salivary proteome changes. Therefore, saliva proteomic analysis was a useful approach to evaluate the rapid responses associated to an acute stress test also highlighting known biomarkers.

Distinct Regulation of Dopamine D3 Receptor in the Basolateral Amygdala and Dentate Gyrus during the Reinstatement of Cocaine CPP Induced by Drug Priming and Social Stress

Relapse in the seeking and intake of cocaine is one of the main challenges when treating its addiction. Among the triggering factors for the recurrence of cocaine use are the re-exposure to the drug and stressful events. Cocaine relapse engages the activity of memory-related nuclei, such as the basolateral amygdala (BLA) and the hippocampal dentate gyrus (DG), which are responsible for emotional and episodic memories. Moreover, D3 receptor (D3R) antagonists have recently arisen as a potential treatment for preventing drug relapse. Thus, we have assessed the impact of D3R blockade in the expression of some dopaminergic markers and the activity of the mTOR pathway, which is modulated by D3R, in the BLA and DG during the reinstatement of cocaine-induced conditioned place preference (CPP) evoked by drug priming and social stress. Reinstatement of cocaine CPP paralleled an increasing trend in D3R and dopamine transporter (DAT) levels in the BLA. Social stress, but not drug-induced reactivation of cocaine memories, was prevented by systemic administration of SB-277011-A (a selective D3R antagonist), which was able, however, to impede D3R and DAT up-regulation in the BLA during CPP reinstatement evoked by both stress and cocaine. Concomitant with cocaine CPP reactivation, a diminution in mTOR phosphorylation (activation) in the BLA and DG occurred, which was inhibited by D3R blockade in both nuclei before the social stress episode and only in the BLA when CPP reinstatement was provoked by a cocaine prime. Our data, while supporting a main role for D3R signalling in the BLA in the reactivation of cocaine memories evoked by social stress, indicate that different neural circuits and signalling mechanisms might mediate in the reinstatement of cocaine-seeking behaviours depending upon the triggering stimuli.

Null effects of therapy dog interaction on adolescent anxiety during a laboratory-based social evaluative stressor

BACKGROUND AND OBJECTIVES

Animal-assisted interventions (AAIs) are increasingly popular as treatments to reduce anxiety. However, there is little empirical evidence testing the mechanisms of action in AAIs, especially among adolescents. We examined whether two possible mechanisms, social interaction and/or physical contact with a therapy dog, might reduce anxiety during a social stressor.

DESIGN AND METHODS

To test these mechanisms, we randomly assigned 75 adolescents with low, middle, and high levels of social anxiety to complete a laboratory-based social evaluative stressor in one of three conditions: social interaction with a therapy dog (no physical interaction), social plus physical interaction with a therapy dog, or no interaction with a therapy dog. We measured self-reported anxiety and autonomic reactivity during the social stressor to assess the effects of contact with a therapy dog.

RESULTS AND CONCLUSIONS

We found no evidence that the presence of a real dog, with or without the opportunity to touch it, reduced anxiety or autonomic reactivity or improved cognitive performance relative to the presence of a stuffed dog in the control condition, regardless of levels of preexisting social anxiety.Trial registration: ClinicalTrials.gov identifier: NCT03249116.

Oxytocin Signaling as a Target to Block Social Defeat-Induced Increases in Drug Abuse Reward

There is huge scientific interest in the neuropeptide oxytocin (OXT) due to its putative capacity to modulate a wide spectrum of physiological and cognitive processes including motivation, learning, emotion, and the stress response. The present review seeks to increase the understanding of the role of OXT in an individual’s vulnerability or resilience with regard to developing a substance use disorder. It places specific attention on the role of social stress as a risk factor of addiction, and explores the hypothesis that OXT constitutes a homeostatic response to stress that buffers against its negative impact. For this purpose, the review summarizes preclinical and clinical literature regarding the effects of OXT in different stages of the addiction cycle. The current literature affirms that a well-functioning oxytocinergic system has protective effects such as the modulation of the initial response to drugs of abuse, the attenuation of the development of dependence, the blunting of drug reinstatement and a general anti-stress effect. However, this system is dysregulated if there is continuous drug use or chronic exposure to stress. In this context, OXT is emerging as a promising pharmacotherapy to restore its natural beneficial effects in the organism and to help rebalance the functions of the addicted brain.

Genetic and Epigenetic Consequence of Early-Life Social Stress on Depression: Role of Serotonin-Associated Genes

Early-life adversity caused by poor social bonding and deprived maternal care is known to affect mental wellbeing and physical health. It is a form of chronic social stress that persists because of a negative environment, and the consequences are long-lasting on mental health. The presence of social stress during early life can have an epigenetic effect on the body, possibly resulting in many complex mental disorders, including depression in later life. Here, we review the evidence for early-life social stress-induced epigenetic changes that modulate juvenile and adult social behavior (depression and anxiety). This review has a particular emphasis on the interaction between early-life social stress and genetic variation of serotonin associate genes including the serotonin transporter gene (5-HTT; also known as SLC6A4), which are key molecules involved in depression.

Familiarity influences social networks in dairy cows after regrouping

Regrouping is common practice when managing dairy cow groups, and it is known to have disruptive effects on behavior and production. The presence of a small group of familiar cows upon regrouping may provide social support and mitigate some of the negative effects. In this study we investigated (1) how regrouping affects social relationships among familiar cows and (2) if cows prefer familiar individuals over unfamiliar ones as social partners after regrouping. We used 3 established groups of cows to create 2 new groups, each containing 14 cows, using subgroups of familiar animals (i.e., 4, 6, and 4 cows) from the original groups. The new groups were similar in respect to the age, parity, and sire of cows. The frequencies of grooming and displacements were determined in the walking alley, lying stalls, and feed bunk by observing 48 h of continuous video before regrouping, directly after regrouping, and 1 wk later. First, social network analysis was applied to investigate the effects of regrouping on the relationships within the subgroups of familiar cows. Second, we determined if familiar cows were more or less connected than would be expected by chance (i.e., assortment), considering displacement, grooming, and feed bunk neighbor networks (derived from electronic feeder data) after regrouping. Regrouping increased the number of displacements, especially in the walking alley. Within the subgroups of familiar cows, regrouping resulted in slightly more displacements, but the network structure did not change. The frequency of grooming among familiar cows remained stable across all observation periods, and the network structure was not affected by regrouping. We found positive assortment in grooming and feed bunk neighbor networks, thereby suggesting that cows preferred familiar individuals as grooming partners and feeding neighbors directly after regrouping and, to a smaller extent, 1 wk later. The effect of familiarity on displacements depended on the pen area. The weak assortment directly after regrouping at the feed bunk indicated that familiar cows displaced each other more than unfamiliar ones, possibly because they were neighbors more often. Our results indicated that a small group of familiar cows may provide ongoing social buffering after regrouping. Further research with multiple groups and larger group sizes is needed to determine whether similar effects are consistently present when groups of familiar cows are subjected to regrouping.

Toward Understanding the Sex Differences in the Biological Mechanism of Social Stress in Mouse Models

Significant sex differences in terms of prevalence, symptomatic profiles, severity, and comorbidities of psychiatric disorders are quite common. Women have been shown to be more vulnerable to stress and are nearly twice as likely as men to develop stress-related disorders such as depression and anxiety. Therefore, understanding sex differences with respect to the neurobiological mechanisms underlying stress-related disorders is important for developing more efficient pharmacological interventions for women. However, most preclinical studies on stress-related disorders have focused heavily on male rodents. Here, recent developments in the study of repeated social defeat stress models in female mice are summarized. Our findings suggest that a variety of factors need to be considered when employing this model.

Insidious Transmission of a Stress-Related Neuroadaptation

Stress is highly pervasive in humans, impacting motivated behaviors with an enormous toll on life quality. Many of the effects of stress are orchestrated by neuropeptides such as corticotropin-releasing factor (CRF). It has previously been shown that in stress-naïve male mice, CRF acts in the core of the nucleus accumbens (NAc) to produce appetitive effects and to increase dopamine release; yet in stress-exposed male mice, CRF loses its capacity to modulate NAc dopamine release and is aversive. In the current research, we tested whether this effect is comparable in females to males and whether the neuroadaptation is susceptible to social transmission. We found that, like in males, CRF increased dopamine release in stress-naïve but not stress-exposed female mice. Importantly, this persistent physiological change was not accompanied by overt behavioral changes that would be indicative of depression- or anxiety-like phenotype. Nonetheless, when these mice were housed for 7 days with stress-naïve conspecifics, the cage mates also exhibited a loss of dopamine potentiation by CRF. These data demonstrate the asymptomatic, yet pervasive transmission of stress-related neuroadaptations in the population.

Blockade of D3 receptor prevents changes in DAT and D3R expression in the mesolimbic dopaminergic circuit produced by social stress- and cocaine prime-induced reinstatement of cocaine-CPP

BACKGROUND

Cocaine may cause persistent changes in the brain, which are more apparent in DA transporter (DAT) and DA receptor availability within the nucleus accumbens (NAc). On the other hand, the DA D3 receptor (D3R) has emerged as a promising pharmacotherapeutic target for substance use disorders.

AIMS

This study aims to assess the impact of selective D3R antagonism on DAT and D3R after reinstatement of cocaine preference (CPP) induced by an acute session of social defeat stress (SDS) and a cocaine prime in mice after a period of abstinence.

METHODS

Male mice were conditioned with 25 mg/kg of cocaine for 4 days. After 60 days of extinction training mice were pretreated with the selective D3R antagonist SB-277011A before the re-exposure to a priming dose of cocaine or to a single SDS session. CPP scores were determined and levels of DAT, D3R, phospho Akt (pAkt) and phospho mTOR (pmTOR) were assessed in the NAc shell.

RESULTS

An increase in DAT and D3R expression was seen in the NAc after both a cocaine prime- and SDS-induced reinstatement of CPP. Pretreatment with SB-277011A blocked elevated DAT and D3R expression as well as SDS-induced reinstatement. By contrast, the blockade of D3R did not modified the cocaine prime-induced CPP. Changes in DAT and D3R expression do not seem to occur via the canonic pathway involving Akt/mTOR.

CONCLUSIONS

Our results suggest that the selective D3R antagonist ability to inhibit DAT and D3R up-regulation could represent a possible mechanism for its behavioral effects in cocaine-memories reinstatement induced by social stress.

Density-induced social stress alters oxytocin and vasopressin activities in the brain of a small rodent species

It is known that social stress could alter oxytocin (OT) and arginine‐vasopressin (AVP) expression in specific regions of brains which regulate the aggressive behavior of small rodents, but the effects of density‐induced social stress are still unknown. Brandt's voles (Lasiopodomys brandtii) are small herbivores in the grassland of China, but the underlying neurological mechanism of population regulation is still unknown. We tested the effects of housing density of Brandt's voles on OT/AVP system with physical contact (allowing aggression) and without physical contact (not allowing aggression) under laboratory conditions. Then, we tested the effects of paired‐aggression (no density effect) of Brandt's voles on OT/AVP system under laboratory conditions. We hypothesized that high density would increase aggression among animals which would then increase AVP but reduce OT in brains of animals. Our results showed that high housing density induced more aggressive behavior. We found high‐density‐induced social stress (with or without physical contact) and direct aggression significantly increased expression of mRNA and protein of AVP and its receptor, but decreased expression of mRNA and protein of OT and its receptor in specific brain regions of voles. The results suggest that density‐dependent change of OT/AVP systems may play a significant role in the population regulation of small rodents by altering density‐dependent aggressive behavior.

Everyday discrimination and subsequent cognitive abilities across five domains

OBJECTIVE

Previous research suggests that everyday discrimination is associated with worse concomitant performance in several cognitive domains, as well as faster subsequent declines in episodic memory. This study aimed to extend knowledge on the specificity, durability, and mechanisms of associations between everyday discrimination and cognition by using a comprehensive neuropsychological battery and a longitudinal mediation design.

METHOD

Participants included 3,304 older adults in the Health and Retirement Study Harmonized Cognitive Assessment Protocol. Discrimination was assessed using the Everyday Discrimination Scale. Depressive symptoms were assessed with the 8-item Center for Epidemiological Studies Depression Scale. Vascular diseases were quantified as the self-reported presence of hypertension, diabetes, and heart disease. Confirmatory factor analysis was used to estimate episodic memory, executive functioning, processing speed, language, and visuoconstruction across a battery of 13 neuropsychological tests. Structural equation models controlled for sociodemographics and baseline cognition ascertained 2 to 4 years prior.

RESULTS

Discrimination was associated with more depressive symptoms and vascular diseases. Depressive symptoms mediated negative effects of discrimination on subsequent functioning across all 5 cognitive domains. Vascular diseases additionally mediated negative effects of discrimination on processing speed. After accounting for mediators, direct negative effects of discrimination remained for executive functioning and visuoconstruction.

CONCLUSIONS

This national longitudinal study in the United States provides evidence for broad and enduring effects of everyday discrimination on cognitive aging, which appear to be partially mediated by mental and physical health. Future research should examine additional mechanisms as well as moderators of these associations to better understand points of intervention. (PsycInfo Database Record (c) 2020 APA, all rights reserved).

Racial Disparities in Associations between Neighborhood Demographic Polarization and Birth Weight

Neighborhood demographic polarization, or the extent to which a privileged population group outnumbers a deprived group, can affect health by influencing social dynamics. While using birth records from 2001 to 2013 in Massachusetts (n = 629,675), we estimated the effect of two demographic indices, racial residential polarization (RRP) and economic residential polarization (ERP), on birth weight outcomes, which are established predictors of the newborn's future morbidity and mortality risk. Higher RRP and ERP was each associated with higher continuous birth weight and lower odds for low birth weight and small for gestational age, with evidence for effect modification by maternal race. On average, per interquartile range increase in RRP, the birth weight was 10.0 g (95% confidence interval: 8.0, 12.0) higher among babies born to white mothers versus 6.9 g (95% CI: 4.8, 9.0) higher among those born to black mothers. For ERP, it was 18.6 g (95% CI: 15.7, 21.5) higher among those that were born to white mothers versus 1.8 g (95% CI: -4.2, 7.8) higher among those born to black mothers. Racial and economic polarization towards more privileged groups was associated with healthier birth weight outcomes, with greater estimated effects in babies that were born to white mothers than those born to black mothers.

Social Stress Increases Vulnerability to High-Fat Diet-Induced Insulin Resistance by Enhancing Neutrophil Elastase Activity in Adipose Tissue

Social stress (SS) has been linked to the development of cardiovascular disease (CVD), which is closely associated with insulin resistance (IR); however, the causal effect of SS on IR remains unclear. The 8-week-old male C57BL/6 mice were exposed to SS by housing with a larger CD-1 mouse in a shared home cage without physical contact for 10 consecutive days followed by high-fat diet (HFD) feeding. Control mice were housed in the same cage without a CD-1 mouse. After 6 weeks of HFD, insulin sensitivity was significantly impaired in stressed mice. While the percentage of classically activated macrophages in epididymal white adipose tissue (eWAT) was equivalent between the two groups, the percentage of lymphocyte antigen 6 complex locus G6D (Ly-6G)/neutrophil elastase (NE)-double positive cells markedly increased in stressed mice, accompanied by augmented NE activity assessed by ex vivo eWAT fluorescent imaging. Treatment with an NE inhibitor completely abrogated the insulin sensitivity impairment of stressed mice. In vitro NE release upon stimulation with a formyl peptide receptor 1 agonist was significantly higher in bone marrow neutrophils of stressed mice. Our findings show that SS-exposed mice are susceptible to the development of HFD-induced IR accompanied by augmented NE activity. Modulation of neutrophil function may represent a potential therapeutic target for SS-associated IR.

Single-Cell Gene Profiling Reveals Social Status-Dependent Modulation of Nuclear Hormone Receptors in GnRH Neurons in a Male Cichlid Fish

Gonadotropin-releasing hormone (GnRH) is essential for the initiation and maintenance of reproductive functions in vertebrates. To date, three distinct paralogue lineages, GnRH1, GnRH2, and GnRH3, have been identified with different functions and regulatory mechanisms. Among them, hypothalamic GnRH1 neurons are classically known as the hypophysiotropic form that is regulated by estrogen feedback. However, the mechanism of action underlying the estrogen-dependent regulation of GnRH1 has been debated, mainly due to the coexpression of low levels of estrogen receptor (ER) genes. In addition, the role of sex steroids in the modulation of GnRH2 and GnRH3 neurons has not been fully elucidated. Using single-cell real-time PCR, we revealed the expression of genes for estrogen, androgen, glucocorticoid, thyroid, and xenobiotic receptors in GnRH1, GnRH2, and GnRH3 neurons in the male Nile tilapia Oreochromis niloticus. We further quantified expression levels of estrogen receptor genes (ERα, ERβ, and ERγ) in three GnRH neuron types in male tilapia of two different social statuses (dominant and subordinate) at the single cell level. In dominant males, GnRH1 mRNA levels were positively proportional to ERγ mRNA levels, while in subordinate males, GnRH2 mRNA levels were positively proportional to ERβ mRNA levels. These results indicate that variations in the expression of nuclear receptors (and possibly steroid sensitivities) among individual GnRH cells may facilitate different physiological processes, such as the promotion of reproductive activities through GnRH1 neurons, and the inhibition of feeding and sexual behaviors through GnRH2 neurons.

Chronic Psychosocial Stress Causes Increased Anxiety-Like Behavior and Alters Endocannabinoid Levels in the Brain of C57Bl/6J Mice

Introduction: Chronic stress causes a variety of physiological and behavioral alterations, including social impairments, altered endocrine function, and an increased risk for psychiatric disorders. Thereby, social stress is one of the most effective stressful stimuli among mammals and considered to be one of the major risk factors for the onset and progression of neuropsychiatric diseases. For analyzing the effects of social stress in mice, the resident/intruder paradigm of social defeat is a widely used model. Although the chronic social defeat stress model has been extensively studied, little is known about the effects of repeated or chronic social defeat stress on the endocannabinoid system (ECS). The present study aimed to understand the effects of chronic social stress on anxiety behavior and the levels of endocannabinoids (ECs) and two N-acylethanolamines (NAEs) in different brain regions of mice. Materials and Methods: Two-month-old, male C57Bl/6J mice were exposed to chronic psychosocial stress for 3 weeks. The effects of stress on anxiety behavior were measured using the light-dark box and hole board test. The EC levels of 2-arachidonoyl glycerol (2-AG) and anandamide (N-arachidonoylethanolamine [AEA]), as well as the levels of two NAEs (oleoylethanolamide [OEA] and palmitoylethanolamide), were analyzed by liquid chromatography-tandem mass spectrometry in the hippocampus, cerebellum, and cortex. Results: In comparison with control mice (n=12), mice exposed to social defeat stress (n=11) showed increased anxiety behaviors in the light-dark box and hole board test and gained significantly more weight during the experimental period. Additionally, chronic social stress induced differential alterations in the brain levels of 2-AG and AEA. More precisely, 2-AG levels were higher in the cortex and cerebellum, whereas reduced AEA levels were found in the hippocampus. Furthermore, we observed lower OEA levels in the hippocampus. Conclusion: The current study confirms that the ECS plays an essential role in stress responses, whereby its modulation seems to be brain region dependent.

Reward Circuitry and Motivational Deficits in Social Anxiety Disorder: What Can Be Learned From Mouse Models?

Social anxiety disorder (SAD) is a common and serious psychiatric condition that typically emerges during adolescence and persists into adulthood if left untreated. Prevailing interventions focus on modulating threat and arousal systems but produce only modest rates of remission. This gap in efficacy suggests that most mainstream treatment concepts do not sufficiently target core processes involved in the onset and maintenance of SAD. This idea has further driven the development of new theoretical models that target dopamine (DA)-driven reward circuitry and motivational deficits that appear to be systematically altered in SAD. Most of the available data linking systemic alterations in DA neurobiology to SAD in humans, although abundant, remains at the level of correlational evidence. Accordingly, the purpose of this brief review is to critically evaluate the relevance of experimental work in rodent models that link details of DA function to symptoms of social anxiety. We conclude that, despite certain systematic limitations inherent in animal models, these approaches provide useful insights into human biomarkers of social anxiety including that (1) adolescence may serve as a critical period for the convergence of neurobiological and environmental factors that modify future expectations about social reward through experience dependent changes in DA-ergic circuitry, (2) females may show unique susceptibility to social anxiety symptoms when encountering relational instability that influences DA-related neural processes, and (3) separate from fear and arousal systems, the functional neurobiology of central DA systems contribute uniquely to susceptibility and maintenance of anhedonic factors relevant to human models of SAD.

Interpersonal life stress, inflammation, and depression in adolescence: Testing Social Signal Transduction Theory of Depression

BACKGROUND

Depression rates increase markedly for girls across the adolescent transition, but the social-environmental and biological processes underlying this phenomenon remain unclear. To address this issue, we tested a key hypothesis from Social Signal Transduction Theory of Depression, which posits that individuals who mount stronger inflammatory responses to social stress should exhibit greater increases in depressive symptoms following interpersonal life stress exposure than those who mount weaker inflammatory responses to such stress.

METHOD

Participants were 116 adolescent girls (M_age  = 14.71) at risk for psychopathology, defined as having a history of mental health concerns (e.g., psychiatric treatment, significant symptoms) over the past 2 years. At baseline, we characterized their inflammatory reactivity to social stress by quantifying their salivary proinflammatory cytokine responses to a laboratory-based social stressor. Then, 9 months later, we assessed the interpersonal and noninterpersonal stressful life events that they experienced over the prior 9 months using an interview-based measure of life stress.

RESULTS

As hypothesized, greater interpersonal life stress exposure was associated with significant increases in depression over time, but only for girls exhibiting stronger salivary tumor necrosis factor-α and interleukin-1β reactivity to social stress. In contrast, noninterpersonal stress exposure was unrelated to changes in depression longitudinally, both alone and when combined with youths' cytokine reactivity scores.

DISCUSSION

These results are consistent with Social Signal Transduction Theory of Depression and suggest that heightened inflammatory reactivity to social stress may increase adolescents' risk for depression. Consequently, it may be possible to reduce depression risk by modifying inflammatory responses to social stress.

Social Stress-Induced Postsynaptic Hyporesponsiveness in Glutamatergic Synapses Is Mediated by PSD-Zip70-Rap2 Pathway and Relates to Anxiety-Like Behaviors

PSD-Zip70 is a postsynaptic protein that regulates glutamatergic synapse formation and maturation by modulation of Rap2 activity. PSD-Zip70 knockout (PSD-Zip70KO) mice exhibit defective glutamatergic synaptic transmission in the prefrontal cortex (PFC) with aberrant Rap2 activation. As prefrontal dysfunction is implicated in the pathophysiology of stress-induced psychiatric diseases, we examined PSD-Zip70KO mice in a social defeat (SD) stress-induced mouse model of depression to investigate stress-induced alterations in synaptic function. Compared with wild-type (WT) mice, PSD-Zip70KO mice exhibited almost normal responses to SD stress in depression-related behaviors such as social activity, anhedonia, and depressive behavior. However, PSD-Zip70KO mice showed enhanced anxiety-like behavior irrespective of stress conditions. The density and size of dendritic spines of pyramidal neurons were reduced in the medial PFC (mPFC) in mice exposed to SD stress. Phosphorylation levels of the AMPA–type glutamate receptor (AMPA-R) GluA2 subunit at Ser880 were prominently elevated in mice exposed to SD stress, indicating internalization of surface-expressed AMPA-Rs and decreased postsynaptic responsiveness. Structural and functional impairments in postsynaptic responsiveness were associated with Rap2 GTPase activation in response to SD stress. Social stress-induced Rap2 activation was regulated by a PSD-Zip70-dependent pathway via interaction with SPAR/PDZ-GEF1. Notably, features such as Rap2 activation, dendritic spine shrinkage, and increased GluA2 phosphorylation were observed in the mPFC of PSD-Zip70KO mice even without SD stress. Together with our previous results, the present findings suggest that SD stress-induced postsynaptic hyporesponsiveness in glutamatergic synapses is mediated by PSD-Zip70-Rap2 signaling pathway and closely relates to anxiety-like behaviors.

Dynamic changes in thalamic connectivity following stress and its association with future depression severity

INTRODUCTION

Tracking stress-induced brain activity and connectivity dynamically and examining activity/connectivity-associated recovery ability after stress might be an effective way of detecting stress vulnerability.

METHODS

Using two widely used stress paradigms, a speech task (social stress) and a mathematical calculation task (mental loading stress), we examined common changes in regional homogeneity (ReHo) and functional connectivity (FC) before, during, and after the two stressful tasks in thirty-nine college students. A counting breath relaxation task was employed as a contrast task. ReHo and FC were compared between subjects with higher versus lower depression symptoms (assessed by the Beck Depression Inventory, BDI). We developed a recovery index (RI) based on dynamic changes of ReHo/FC to evaluate individuals' ability to recover from a stressful state. To assess RI's usefulness in predicting future depression severity, BDI was also measured at one-year follow-up.

RESULTS

Our results revealed a ReHo decrease after both stressful tasks and a ReHo increase after the relaxation task in bilateral thalamus. The ReHo decrease after both stressful tasks was more significant in the higher BDI than the lower BDI group. Higher ReHo RI of the right thalamus in the higher BDI groups was significantly correlated with lower BDI severity at one-year follow-up. Bilateral thalamus also showed increased FC with the default mode network and decreased FC with the executive control network after the stressful tasks.

CONCLUSION

These findings highlight the importance of tracking resting activity and connectivity of thalamus dynamically for detecting stress vulnerability.

Social instability in adolescence differentially alters dendritic morphology in the medial prefrontal cortex and its response to stress in adult male and female rats

Adolescence is an important period for HPA axis development and synapse maturation and reorganization in the prefrontal cortex (PFC). Thus, stress during adolescence could alter stress-sensitive brain regions such as the PFC and may alter the impact of future stressors on these brain regions. Given that women are more susceptible to many stress-linked psychological disorders in which dysfunction of PFC is implicated, and that this increased vulnerability emerges in adolescence, stress during this time could have sex-dependent effects. Therefore, we investigated the effects of adolescent social instability stress (SIS) on dendritic morphology of Golgi-stained pyramidal cells in the medial PFC of adult male and female rats. We then examined dendritic reorganization following chronic restraint stress (CRS) with and without a rest period in adult rats that had been stressed in adolescence. Adolescent SIS conferred long-term alterations in prelimbic of males and females, whereby females show reduced apical length and basilar thin spine density and males show reduced basilar length. CRS in adulthood failed to produce immediate dendritic remodeling in SIS rats. However, CRS followed by a rest period reduced apical dendritic length and increases mushroom spine density in adolescently stressed adult males. Conversely, CRS followed by rest produced apical outgrowth and decreased mushroom spine density in adolescently stressed adult females. These results suggest that stress during adolescence alters development of the PFC and modulates stress-induced dendritic changes in adulthood.