Habituation to repeated stress: get used to it

Habituation to novel stimuli alters hippocampal plasticity associated with morphine tolerance in male Wistar rats

Chronic morphine exposure affects neuroplasticity in the hippocampus, a key area for learning and memory. Since, novelty exploration influence rodent hippocampal plasticity, the aim of this study was to investigate the effects of habituation to novel contexts and odors on hippocampal plasticity in morphine-tolerant rats. For this purpose, neurogenesis markers, dendritic spine density and mRNA levels for various genes encoding neurotrophic factors were evaluated in the hippocampus tissue (ventral, vH vs. dorsal, dH) of male rats. Habituation to the new environment was established using animal models of morphine tolerance. Following multiple exposures to a novel context (open field habituation, OFH) or a series of novel odors (odor habituation, OH), markers (Ki67 or DCX) associated with neurogenesis were found to be lower in the morphine-tolerant rats that underwent habituation than the non-habituated morphine-tolerant rats, with specific regions (dH, vH), being differently influenced by specific type of habituation (OFH, OH, respectively). Further results showed subregion and habituation specific effects on the number of dendritic spines per spine type or levels of neurotropic factors including BDNF and TrkB mRNA levels in the dH and vH in morphine-tolerant rats that underwent habituation as compared to the non-habituated morphine-tolerant rats. We provide new evidence that habituation to novel contexts and novel odors appears to affect hippocampal plasticity in morphine-tolerant rats and that pro-plasticity molecules appear to mediate habituation effects on morphine tolerance plasticity.

Getting used to it? Stress of repeated management procedures in semi-domesticated reindeer

BACKGROUND

Extensive animal production systems, such as reindeer husbandry may represent a system to further study the context dependence of stress responses and the potential implications for animal welfare as research on food animal stress and welfare has so far primarily focused on animals in intensive animal production systems while animals from extensive production systems, such as reindeer, are yet underrepresented. We investigated short- and longer-term stress responses to repeated herding, handling and restraint and its potential effect on animal welfare in semi-domesticated adult female reindeer (Rangifer tarandus tarandus). We also assessed seasonal differences and the potential effect of the additional stressor of calf removal using serum concentrations of glucocorticoids (cortisol, cortisone and corticosterone), their precursors (11-desoxcortisol, 17-α-hydroxyprogesterone and deoxycorticosterone) and catecholamine metabolites (metanephrine and normetanephrine) in combination with the immunological stress proxy leukocyte coping capacity (LCC) and rectal temperature. Additionally, we assessed the interconnections among different stress indices and their suitability as stress indicators to evaluate handling-induced stress in reindeer, where rectal temperature, other than serum cortisol levels, emerged as a robust and integrative stress parameter.

RESULTS

Herding, handling, and restraint elicited a marked and seasonally different short-term stress response with higher stress mediator levels in winter. Further, females who had their calf removed shortly after parturition showed increased stress levels based on LCC. The repeated exposure to the same stressors led to a habituation, with decreasing levels of stress indices to the procedure in both seasons. This outcome implies that reindeer females in the present study were able to cope well with repeated manipulations and that this intensification may not compromise animal welfare. Notably, the traditional stress index body temperature correlated with various stress indices encompassing the HPA axis response (cortisol and corticosterone in summer and additionally cortisone and 11-deoxycortisol in winter), the sympathetic-adrenal-medullary system (metanephrine) as well as the immunological response to stress (LCC), in both seasons.

CONCLUSION

Our results emphasise body (rectal) temperature as a robust and integrative stress parameter in the context of our study. Our findings add to a foundation for evaluating available stress indices in different individual and environmental contexts and may contribute to improved animal management practices aimed at reducing stress levels and enhancing animal welfare.

Incidence of adverse perinatal outcomes in highly vulnerable pregnant women - the Mothers of Rotterdam study

BACKGROUND

Socioeconomic disadvantaged circumstances are known to affect health outcomes, but during pregnancy it also affects the growth and development of the fetus. This often results in adverse perinatal outcomes and other long lasting effects. Here we refer to pregnant women living in such circumstances as a highly vulnerable population.

OBJECTIVES

To study adverse perinatal outcomes in highly vulnerable pregnant women within the Mothers of Rotterdam (MoR) study and to compare findings to the outcomes of women in the Netherlands as a whole and the city of Rotterdam.

METHODS

Pregnancy and childbirth data from women participating in the MoR study (2015-2019) was requested from their obstetric professional. For comparison, data from the Dutch national birth registry (Perined) were used representing women in the Netherlands and Rotterdam. Main outcome measures were preterm birth (PTB) and small for gestational age (SGA). Secondary outcome measures were perinatal mortality and a low Apgar score. Only singleton viable pregnancies (i.e. birthweight above 500 g or born after 22 + 0 weeks of gestation) were included in this study. Prevalence rates and corresponding 95% confidence intervals (95%CI) were calculated for all outcomes in each group. Direct standardization was used to account for possible differences in case-mix composition between the studied groups.

RESULTS

Data on 346 childbirths within the MoR study were retrieved and compared to 813,755 and 34,009 childbirths in the Netherlands and Rotterdam, respectively. The prevalence of PTB (4.34% (95%CI 2.19-6.48) was lower in the MoR population compared to both the Netherlands (6.21% (95%CI 6.16-6.27)) and Rotterdam (6.39% (95%CI 6.13-6.65)). The prevalence of SGA (21.09% (95% CI 16.80-25.40)) was higher in the MoR population compared to both the Netherlands (10.11% (95%CI 10.04-10.17)) and Rotterdam (13.28% (95%CI 12.92-13.65)). There were no cases of perinatal mortality registered in the MoR population. The prevalence of a low Apgar score (0.87% (95%CI 0.00-1.84)) was lower in the MoR population.

CONCLUSIONS

Our study found unexpected low PTB and high SGA prevalence rates in the MoR population compared to the Netherlands and Rotterdam. Mechanisms through which socioeconomic disadvantaged circumstances affect perinatal health seem to work differently in various strata of vulnerable populations.

Cortisol as a Biomarker for Stress During the Assessment and Treatment of Destructive Behavior

Behavior-analytic treatments successfully reduce individuals' destructive behavior (e.g., self-injurious behavior, aggression, property destruction, disruption); however, there is limited research evaluating these treatments' effects on individuals' physiological stress responses, even though stress can have significant negative impacts on quality of life. Research from other fields has demonstrated that salivary cortisol concentration is a valid biomarker for stress, so researchers could potentially use this biomarker to assess the stress of individuals with limited communication repertoires who also engage in destructive behavior. The purpose of this research was to assess changes in salivary cortisol concentrations as a biomarker for stress with two participants to evaluate whether conditions that evoke destructive behavior induce stress relative to conditions that do not evoke destructive behavior. For one participant, salivary cortisol concentrations tended to increase following exposures to stimuli that evoked destructive behavior compared to conditions that did not evoke destructive behavior. The other participant had elevated salivary cortisol concentrations across all conditions. Salivary cortisol may be a useful biomarker for evaluating physiological stress as an outcome measure during research on the assessment and treatment of destructive behavior.

Similarity-based context aware continual learning for spiking neural networks

Biological brains have the capability to adaptively coordinate relevant neuronal populations based on the task context to learn continuously changing tasks in real-world environments. However, existing spiking neural network-based continual learning algorithms treat each task equally, ignoring the guiding role of different task similarity associations for network learning, which limits knowledge utilization efficiency. Inspired by the context-dependent plasticity mechanism of the brain, we propose a Similarity-based Context Aware Spiking Neural Network (SCA-SNN) continual learning algorithm to efficiently accomplish task incremental learning and class incremental learning. Based on contextual similarity across tasks, the SCA-SNN model can adaptively reuse neurons from previous tasks that are beneficial for new tasks (the more similar, the more neurons are reused) and flexibly expand new neurons for the new task (the more similar, the fewer neurons are expanded). Selective reuse and discriminative expansion significantly improve the utilization of previous knowledge and reduce energy consumption. Extensive experimental results on CIFAR100, ImageNet generalized datasets, and FMNIST-MNIST, SVHN-CIFAR100 mixed datasets show that our SCA-SNN model achieves superior performance compared to both SNN-based and DNN-based continual learning algorithms. Additionally, our algorithm has the capability to adaptively select similar groups of neurons for related tasks, offering a promising approach to enhancing the biological interpretability of efficient continual learning.

High intensity approaches to exposure and response prevention for obsessive-compulsive disorder

Obsessive-compulsive disorder (OCD) is a debilitating psychiatric condition with multidetermined etiological and maintaining mechanisms. Cognitive behavioral therapy (CBT), specifically exposure and response prevention (ERP), is the first line behavioral intervention to treat OCD. ERP directly targets threat learning that characterizes OCD through processes of habituation (fear extinction) and inhibitory learning, in addition to eliciting neuronal changes implicated in OCD. Although ERP has a strong evidence base, not all OCD patients respond fully to standard, weekly or twice-weekly outpatient ERP. High intensity ERP-treatment delivered through more and/or longer sessions in a condensed manner-is a potential alternative approach that has also demonstrated efficacy for adults and youth with OCD. The goal of this review article is to describe the nature, rationale, and evidence for high intensity ERP for OCD treatment. We describe the foundations of ERP for OCD, various formats of intensive ERP, clinical research on the efficacy of this approach including neuronal changes, and potential pharmacological and neurosurgical augmentation strategies. We conclude with limitations of the current literature on intensive approaches and recommendations for future directions. While additional research is needed, high intensity ERP may be a promising approach for patients who have not responded to standard ERP or for patients requiring rapid symptom improvement.

Assessment of PTSD in military personnel via machine learning based on physiological habituation in a virtual immersive environment

Posttraumatic stress disorder (PTSD) is a complex mental health condition triggered by exposure to traumatic events that leads to physical health problems and socioeconomic impairments. Although the complex symptomatology of PTSD makes diagnosis difficult, early identification and intervention are crucial to mitigate the long-term effects of PTSD and provide appropriate treatment. In this study, we explored the potential for physiological habituation to stressful events to predict PTSD status. We used passive physiological data collected from 21 active-duty United States military personnel and veterans in an immersive virtual environment with high-stress combat-related conditions involving trigger events such as explosions or flashbangs. In our work, we proposed a quantitative measure of habituation to stressful events that can be quantitatively estimated through physiological data such as heart rate, galvanic skin response and eye blinking. Using a Gaussian process classifier, we prove that habituation to stressful events is a predictor of PTSD status, measured via the PTSD Checklist Military version (PCL-M). Our algorithm achieved an accuracy of 80.95% across our cohort. These findings suggest that passively collected physiological data may provide a noninvasive and objective method to identify individuals with PTSD. These physiological markers could improve both the detection and treatment of PTSD.

The gold standard control groups in physiological and pharmacological research are not that shiny: Intraperitoneal saline injection and needle pricking affect prepubescent mice's behavior in a sex-specific manner

Study design and experimental tools are crucial for good quality science, and an essential part of it is the choice of control groups to best test the hypothesis. Two of the standard control groups in physiological and pharmacological research are needle pricking without substance injection (Sham) and/or vehicle injection (Saline). However, both needle pricking and saline injection can act as stressors, potentially influencing the analyzed outcome. This raises the question of whether the dependent variable remains unaffected by the stress induced by these procedures. Despite the significance of this issue, very few studies have investigated the behavioral effects of a single intraperitoneal (I.P.) Sham and/or single I.P. Saline injection in mice, and those that have used mostly adult males. In this study, we investigated if a single I.P. Sham and/or I.P. Saline injection affects female and male prepubertal (4-weeks-old) mice behavior. After Sham or Saline injection, we examined exploratory/motor behavior (open field test - OFT), anxiety-like behavior (elevated plus-maze - EPM), and behavioral despair/depressive-like behavior (forced swimming test - FST). We observed that both Sham prepubertal females and males showed behavioral alterations in OFT and EPM, and Saline males showed behavioral alterations in OFT and FST. On the other hand, prepubertal Saline females showed an increase in exploratory behavior, risk assessment/anxiety-like behavior, and behavioral despair/depressive-like behavior. Thus, our findings indicate that control procedures commonly used in physiological and pharmacological experimental designs affect the behavior of prepubescent mice, with more pronounced effects in females than in males. This study suggests considering Naïve animals together with Sham and/or Vehicle for a better and more honest interpretation of the data.

Influence of strain on expression and habituation of autonomic and cardiovascular responses to restraint stress in rats

This study aimed to evaluate the influence of rat strain in expression of autonomic and cardiovascular changes during acute exposure to restraint stress, as well as in habituation of these physiological responses upon repeated exposure to restraint. For this, blood pressure, heart rate (HR) and sympathetically-mediated cutaneous vasoconstriction were assessed in Wistar (control strain), Long-Evans, Holtzman and spontaneously hypertensive (SHR) rats during acute or 10th 60-min session of restraint stress. We observed that HR returned faster to baseline values during recovery of the acute session of restraint in Long-Evans and SHR rats in relation to Wistar, thus indicating shorter tachycardia in these strains. Long-Evans also presented enhanced sympathetically-mediated cutaneous vasoconstriction to acute restraint stress. Habituation of the tachycardiac response evidenced as a faster HR return to baseline values during recovery of the 10th restraint session in relation to acute stress was similarly identified in both Wistar and Holtzman rats. However, cardiovascular changes were similarly evoked during acute and 10th restraint stress session in SHR and Long-Evans rats. Taken together, these findings indicate that both cardiovascular responses during acute stress and habituation of these physiological adjustments upon repeated exposure to the same stressor are strain-dependent. Differences were mainly observed in Long-Evans and SHR strains, whereas Holtzman rats seem to present similar autonomic and cardiovascular changes in relation to Wistar rats.

Spontaneous Pain and Pain Sensitivity in Response to Prolonged Experimental Sleep Disturbances-Potential Sex Differences

INTRODUCTION

Insomnia is a highly prevalent condition that predisposes individuals to many chronic pain disorders, with most of them showing pronounced sexual dimorphism. We investigated whether experimental insomnia-like sleep disturbances (ESD) affect spontaneous pain and pain sensitivity, and whether sex modulates pain responses.

METHODS

Twenty-four healthy participants (50% females, age 28.3 ± 5.9 years) participated in a study consisting of two 19-day in-laboratory protocols-an ESD protocol consisting of repeated nights of short and disrupted sleep with intermittent nights of undisturbed sleep and a control sleep (CS) protocol consisting of 18 nights with an undisturbed 8-h sleep opportunity. Spontaneous pain was assessed using electronic rating scales during daytime and night-time wake periods. Pain sensitivity was assessed through pressure and heat pain threshold measures every other day of the protocol.

RESULTS

Females responded with higher daytime pain ratings in the ESD compared to the CS condition, while males responded with lower pain ratings (p < 0.05 for condition*sex). Spontaneous pain ratings were higher at night-time than during daytime and worsened across successive nights of sleep disturbances, independent of sex (p < 0.05 for condition*study day*daytime-night-time). Females developed greater pressure pain sensitivity, while males developed greater pain sensitivity to heat in the ESD compared to the CS condition (p < 0.05 for condition*sex).

CONCLUSION

Pain responses to sleep disturbances strongly vary by sex and may contribute to sex differences in the prevalence and symptom burden of many chronic pain conditions. Because the study was not a priori powered on sex, findings are preliminary and require follow-up in larger samples. Findings further suggest to specifically target night-time pain in sleep disturbed individuals, for example, through optimised timing of analgesic-acting medications.

SIGNIFICANCE

Exploration of sex as a modulator suggest that sleep disturbances amplify spontaneous pain and pressure pain sensitivity to a greater extent in females than in males, and this may contribute to females' overrepresentation and disproportionate symptom burden observed for many pain-related disorders for which insomnia is comorbid or a risk factor.

Atrazine's effects on mammalian physiology

Atrazine is a chlorotriazine herbicide that is one of the most widely used herbicides in the USA and the world. For over 60 years atrazine has been used on major crops including corn, sorghum, and sugarcane to control broadleaf and grassy weed emergence and growth. Atrazine has exerted a major economic and environmental impact over that time, resulting in reduced production costs and increased conservation tillage practices. However, widespread use and a long half-life led to a high prevalence of atrazine in the environment. Indeed, atrazine is the most frequent herbicide contaminant detected in water sources in the USA. Due to its almost ubiquitous presence and questions regarding its safety, atrazine has been well-studied. First reported to affect reproduction with potential disruptive effects which were later linked to the immune system, cancer, stress response, neurological disorders, and cardiovascular ailments in experimental models. Atrazine impact on multiple interwoven systems broadens the significance of atrazine exposure. The endeavor to uncover the mechanisms underlying atrazine-induced dysfunction in mammals is ongoing, with new genetic and pharmacological targets being reported. This review aims to summarize the prominent effects of atrazine on mammalian physiology, primarily focusing on empirical studies conducted in lab animal models and establish correlations with epidemiological human studies when relevant. In addition, current common patterns of toxicity and potential underlying mechanisms of atrazine action will be examined.

Effects of voluntary or involuntary exercise in adolescent male rats exposed to chronic social isolation on cognition, behavior, and neurotrophic factors

This study investigated the effects of voluntary and involuntary/regular exercise on neurotrophic factors in the brain, cognitive functions, and anxiety in socially isolated adolescent male rats. In this study, 42 adolescent male Sprague-Dawley rats were divided into six groups: control (C), socially isolated (SI), voluntary exercise (VE), regular exercise (RE), socially isolated + voluntary exercise (SI-VE), and socially isolated + regular exercise (SI-RE). Socially isolated groups were kept in separate cages for 4 weeks. Treadmill and wheel running were used in the exercise groups. The following behavioral tests-elevated plus maze (EPM), open field, ultrasonic vocalization (USV), and Morris water maze (MWM)-rats were euthanized, and brain-derived neurotrophic factor (BDNF), nerve growth factor (NGF), and vascular endothelial growth factor (VEGF) levels were measured in the prefrontal cortex (PFC) and hippocampus. Statistically, the differences between the groups were evaluated by one-way ANOVA and post hoc LSD tests using IBM SPSS software. In the EPM, locomotor activity was higher in the voluntary exercise groups. In the MWM, both regular exercise groups found the platform faster. In the USV, the SI-RE group produced more 50-kHz sounds. BDNF and NGF levels in the hippocampus were higher in the SI-RE and SI-VE groups; VEGF levels were higher in the SI-RE group. Neuron density in the PFC increased in the SI-RE and VE groups, while neuron density in the hippocampus increased in the SI-RE, SI-VE, and VE groups. According to the findings, we showed that voluntary exercise reduces social isolation-induced anxiety, and involuntary/regular exercise both reduces anxiety and has potential benefits on cognitive functions.

Repeated stress gradually impairs auditory processing and perception

Repetitive stress, a common feature of modern life, is a major risk factor for psychiatric and sensory disorders. Despite the prevalence of perceptual abnormalities in these disorders, little is known about how repetitive stress affects sensory processing and perception. Here, we combine repetitive stress in mice, longitudinal measurement of cortical activity, and auditory-guided behaviors to test if sound processing and perception of neutral sounds in adults are modulated by repetitive stress. We found that repetitive stress alters sound processing, increasing spontaneous cortical activity while dampening sound-evoked responses in pyramidal and PV cells and heightening sound-evoked responses in SST cells. These alterations in auditory processing culminated in perceptual shifts, particularly a reduction in loudness perception. Additionally, our work reveals that the impact of stress on perception evolves gradually as the stressor persists over time, emphasizing the dynamic and evolving nature of this mechanism. Our findings provide insight into a possible mechanism by which repetitive stress alters sensory processing and behavior, challenging the idea that stress primarily modulates emotionally charged stimuli.

"I'm Ready This Time": Investigating physiological and emotional habituation to repetitive social stress

BACKGROUND

Repetitive stress is at the nexus of acute and chronic stress, and there is limited knowledge about how physiological and emotional responses change with repeated exposure.

PURPOSE

We examined stress-related biomarkers and emotional responses to repeated social stressors, and we tested behavioral moderators.

METHODS

In Study 1, 42 adults completed the Trier Social Stress Test (TSST) twice, 4 months apart. Serum inflammatory cytokines (interleukin-6 [IL-6], tumor necrosis factor-α [TNF-α]), blood pressure, pulse, salivary cortisol, and state-level anxiety were measured surrounding the stressor. In Study 2, 84 married individuals completed two 20-minute discussions of contentious topics in the marriage, 1 month apart. Serum IL-6, TNF-α, blood pressure, pulse, salivary cortisol, and state affect were collected surrounding the conflict. Trained experimenters rated positive and negative behavior during the conflict.

RESULTS

In the repetitive Trier paradigm, participants reported less anxiety (Ps = .048) and had higher anticipatory IL-6 responses (P = .014) at Visit 2, compared to Visit 1. In the repetitive marital conflict paradigm, participants had lower positive affect (P = .0004), as well as systolic blood pressure (SBP) (P = .009), diastolic blood pressure (P = .0003), and pulse (P = .027) habituation at the second visit. Objectively rated negative conflict behavior interacted with visit to predict TNF-α (P = .025) and SBP (P = .037) responses. Positive conflict behavior did not moderate outcomes (Ps > .06).

CONCLUSIONS

Stress-sensitive systems can habituate or sensitize to even nontraumatic, repetitive social stressors. Patterns of habituation or sensitization may vary by time between repetition, type of social stressor, stress-sensitive system, and participant behavior.

The day-to-day influence of trauma exposure and sleep dysfunction on everyday stress in youth at familial high-risk for psychotic disorders

Cumulative research finds that exposure to childhood trauma, sleep dysfunction, and high stress levels are prevalent in youth diagnosed with and at-risk for psychotic disorders. However, few studies have investigated the association between nightly sleep and moment-to-moment stress in youth who are at familial high-risk (FHR) for psychotic disorders with varying levels of exposure to childhood trauma. The current study examined the day-to-day associations between trauma severity, nightly sleep duration, and next-day momentary stress in 19 FHR and 19 non-psychiatric youth (ages 13-19 years, 66 % girls). Ecological Momentary Assessment was used to assess these variables across three longitudinal timepoints (baseline, 6-months, and 12-months). The FHR group reported greater trauma severity and shorter sleep duration than the non-psychiatric group. In the whole sample, trauma severity and reduced sleep duration were associated with next-day momentary stress. While group status did not moderate the association between sleep duration and next-day momentary stress, group status did moderate the positive association between trauma severity and next-day momentary stress, showing that the association was specific to the non-psychiatric group. Lastly, the effect of nightly sleep duration on next-day momentary stress was significant and negative, but only at low levels of trauma severity for the whole sample. Findings offer preliminary insights into the associations between trauma severity, sleep duration, and momentary stress. Furthermore, this design can provide a foundation for future research examining environmental and psychosocial risk factors that contribute to symptom progression and prognosis of youth who are genetically vulnerable to psychosis.

Examining the applicability of virtual battle space for stress management training in military personnel-A validation study

Military personnel are often exposed to high levels of both physical and psychological challenges in their work environment and therefore it is important to be trained on how to handle stressful situations. The primary aim of this study was to examine whether military-specific virtual battle space (VBS) scenarios could elicit a physiological and subjective stress response in healthy military personnel, as compared to that of a virtual reality height exposure (VR-HE) stress task that has shown to reliably increase stress levels. Twenty participants engaged in two VBS scenarios and the VR-HE during separate sessions, while measurements of heart rate (HR), heart rate variability (HRV), respiration rate, and subjective stress levels were collected. Contrary to our initial expectations, analysis revealed that neither of the VBS scenarios induced a significant stress response, as indicated by stable HR, HRV, and low subjective stress levels. However, the VR-HE task did elicit a significant physiological stress response, evidenced by increased HR and HRV changes, aligning with previous research findings. Moreover, no discernible alterations were detected in cognitive performance subsequent to these stressors. These results suggest that the current VBS scenarios, despite their potential, may not be effective for stress-related training activities within military settings. The absence of a significant stress response in the VBS conditions points to the need for more immersive and engaging scenarios. By integrating interactive and demanding elements, as well as physical feedback systems and real-time communication, VBS training might better mimic real-world stressors and improve stress resilience in military personnel. The findings of this study have broader implications for stress research and training, suggesting the need for scenario design improvements in virtual training environments to effectively induce stress and improve stress management across various high-stress professions.

Provision of supportive care by an NGO in the face of a dual challenge: cancer and wartime

PURPOSE

In this study, we explored the work of Halasartan (Stop Cancer), an Israeli nongovernmental organization (NGO) and unique social support network for cancer patients and survivors aged 18-44, during a war period. Drawing on the conservation of resources (COR) theory, we examined whether self-efficacy, social support, psychological distress, and participation in activities that were geared toward alleviating the war situation at Time 1 (T1) would predict engagement in such activities at Time 2 (T2).

METHODS

A longitudinal design with two time-points was used, and NGO members completed self-report questionnaires. At T1, the cohort comprised 250 members (cancer patients/ survivors); at T2, there were 213. However, only 90 NGO members completed the questionnaires at both time-points.

RESULTS

A significant reduction in psychological distress was observed over time among participants engaged in the NGO's activities, but no differences were observed in participants' self-efficacy or social support. Moreover, participation in NGO activities during wartime at T2 was predicted by biological sex (female), lower self-efficacy, and participation in NGO activities at T1.

CONCLUSION

Halasartan (Stop Cancer) played a pivotal role in offering a sense of normalcy, community, and support to young-adult cancer patients and survivors during a period of war. The study underscores the essential nature of NGO activities tailored to the unique needs of this demographic, particularly in times of crisis. A broader implementation of such supportive interventions to enhance the well-being of vulnerable populations is suggested.

When Common Becomes Normal: Weaker Association Between Neighborhood Stress and Body Mass Index Among Black Adolescents Compared to White Adolescents

Objective

This study explores the relationship between neighborhood stress and Body Mass Index (BMI) in adolescents, while also examining whether this association differs between Black and White adolescents.

Methods

Data from the Adolescent Brain Cognitive Development (ABCD) Study were analyzed using linear regression models to examine the association between neighborhood stress (defined as a composite score based on three items measuring perceived safety and neighborhood fear) and BMI in adolescents, controlling for demographic and socioeconomic variables. We tested models both with and without interaction terms to assess whether race moderated the association. Stratified analyses were conducted to further explore potential differences between Black and White adolescents.

Results

A positive association was observed between neighborhood stress and BMI across the overall sample. However, this association was weaker for Black adolescents compared to White adolescents, even after adjusting for potential confounders.

Conclusions

The contribution of neighborhood stress to higher BMI in adolescents may vary by race. Our findings suggest that while neighborhood stress is associated with increased BMI, Black adolescents appear to be less affected by these stressors than their White peers. This weaker association could be due to the normalization of stress in environments where it is pervasive (what is common becomes normal) or the presence of other significant risk factors affecting BMI in Black youth, such as poverty, limited food access, food culture, and food deserts. Future research should explore processes of habituation, inoculation, or even sensitization to stress among Black populations, who are often exposed to a wide range of stressors throughout the life course.

Is Greener Better? Quantifying the Impact of a Nature Walk on Stress Reduction Using HRV and Saliva Cortisol Biomarkers

The physiological impact of walking in nature was quantified via continuous heart rate variability (HRV), pre- and post-walk saliva cortisol measures, and self-reported mood and mindfulness scores for N = 17 participants who walked "The Green Road" at Walter Reed National Military Medical Center in Bethesda, Maryland. For N = 15 of the participants, HRV analysis revealed two main groups: group one individuals had a 104% increase (mean) in the root mean square standard deviation (RMSSD) and a 47% increase (mean) in the standard deviation of NN values (SDNN), indicating an overall reduction in physiological stress from walking the Green Road, and group two individuals had a decrease (mean) of 42% and 31% in these respective HRV metrics, signaling an increase in physiological stresses. Post-walk self-reported scores for vigor and mood disturbance were more robust for the Green Road than for a comparable urban road corridor and showed that a higher HRV during the walk was associated with improved overall mood. Saliva cortisol was lower after taking a walk for all participants, and it showed that walking the Green Road elicited a significantly larger reduction in cortisol of 53%, on average, when compared with 37% of walking along an urban road. It was also observed that the order in which individuals walked the Green Road and urban road also impacted their cortisol responses, with those walking the urban road before the Green Road showing a substantial reduction in cortisol, suggesting a possible attenuation effect of walking the Green Road first. These findings provide quantitative data demonstrating the stress-reducing effects of being in nature, thus supporting the health benefit value of providing access to nature more broadly in many settings.

Emotional comorbidities in epilepsy result from seizure-induced corticosterone activity

People with epilepsy often have psychiatric comorbidities that can significantly impair their quality of life. We previously reported that repeated seizure activity persistently alters endocannabinoid (eCB) signaling in the amygdala which accounts for comorbid emotional dysregulation in rats, however, the mechanism by which these alterations in eCB signaling within the epileptic brain occur is unclear. Endocannabinoid signaling is influenced by corticosterone (CORT) to modulate cognitive and emotional processes and a hyperactive hypothalamic-pituitary-adrenal (HPA) axis occurs in both people with epilepsy and nonhuman animal models of epilepsy. We employed selective pharmacological tools and a variety of approaches including whole-cell patch-clamp electrophysiology, behavioural paradigms and biochemical assays in amygdala kindled adult male Long-Evans rats. We aimed to determine whether seizures induce hypersecretion of CORT and the role this plays in eCB system dysregulation, impaired fear memory, and anxiety-like behaviours associated with seizure activity. Plasma CORT levels were significantly and consistently elevated following seizures over the course of kindling. Pre-seizure administration with the CORT synthesis inhibitor metyrapone prevented this seizure-induced CORT increase, prevented amygdala anandamide downregulation, and synaptic alteration induced by seizure activity. Moreover, treatment with metyrapone or combined glucocorticoid receptor (GR)/mineralocorticoid receptor (MR) antagonists prior to each elicited seizure were equally effective in preventing chronically altered anxiety-like behaviour and fear memory responses. Inhibiting seizure-induced corticosterone synthesis, or directly blocking the effects of CORT at GR/MR prevents deleterious changes in emotional processing and could be a treatment option for emotional comorbidities in epilepsy.

Effects of exercise on brain-derived neurotrophic factor in Alzheimer's disease models: A systematic review and meta-analysis

A growing body of research examining effects of exercise on brain-derived neurotrophic factor (BDNF) in Alzheimer's disease (AD) models, while due to differences in gender, age, disease severity, brain regions examined, and type of exercise intervention, findings of available studies were conflicting. In this study, we aimed to evaluate current evidence regarding effects of exercise on BDNF in AD models. Searches were performed in PubMed, Web of Science, Cochrane, and EBSCO electronic databases, through July 20, 2023. We included studies that satisfied the following criteria: eligible studies should (1) report evidence on experimental work with AD models; (2) include an exercise group and a control group (sedentary); (3) use BDNF as the outcome indicator; and (4) be randomized controlled trials (RCTs). From 1196 search records initially identified, 36 studies met the inclusion criteria. There was a significant effect of exercise on increasing BDNF levels in AD models [standardized mean differences (SMD) = 0.98, P < 0.00001]. Subgroup analysis showed that treadmill exercise (SMD = 0.92, P< 0.0001), swimming (SMD = 1.79, P< 0.0001), and voluntary wheel running (SMD = 0.51, P= 0.04) were all effective in increasing BDNF levels in AD models. In addition, exercise significantly increased BDNF levels in the hippocampus (SMD = 0.92, P< 0.00001) and cortex (SMD = 1.56, P= 0.02) of AD models. Exercise, especially treadmill exercise, swimming, and voluntary wheel running, significantly increased BDNF levels in hippocampus and cortex of AD models, with swimming being the most effective intervention type.

Long-term, Dynamic Remodelling of the Corticotroph Transcriptome and Excitability After a Period of Chronic Stress

Chronic stress results in long-term dynamic changes at multiple levels of the hypothalamic-pituitary-adrenal (HPA) axis resulting in stress axis dysregulation with long-term impacts on human and animal health. However, the underlying mechanisms and dynamics of altered of HPA axis function, in particular at the level of pituitary corticotrophs, during a period of chronic stress and in the weeks after its cessation (defined as "recovery") are very poorly understood. Here, we address the fundamental question of how a period of chronic stress results in altered anterior pituitary corticotroph function and whether this persists in recovery, as well as the transcriptomic changes underlying this. We demonstrate that, in mice, spontaneous and corticotrophin-releasing hormone-stimulated electrical excitability of corticotrophs, essential for ACTH secretion, is suppressed for weeks to months of recovery following a period of chronic stress. Surprisingly, there are only modest changes in the corticotroph transcriptome during the period of stress, but major alterations occur in recovery. Importantly, although transcriptional changes for a large proportion of mRNAs follow the time course suppression of corticotroph excitability, many other genes display highly dynamic transcriptional changes with distinct time courses throughout recovery. Taken together, this suggests that chronic stress results in complex dynamic transcriptional and functional changes in corticotroph physiology, which are highly dynamic for weeks following cessation of chronic stress. These insights provide a fundamental new framework to further understand underlying molecular mechanisms as well approaches to both diagnosis and treatment of stress-related dysfunction of the HPA axis.

Association Between Organizational Downsizing and Depressive Symptoms Among Korean Workers: A Cross-sectional Analysis

Background

Organizational downsizing may be significantly linked to depressive symptoms, yet research on this impact in Asian contexts is limited. This study investigates the association between downsizing during the COVID-19 pandemic and depressive symptoms across diverse employment statuses.

Methods

This study used the data from 6th Korean Working Conditions Survey. Depressive symptoms were measured using WHO-5 well-being index with a cut-off of 50. Downsizing was defined as decrease in the number of employees during last three years. Multivariable logistic regression adjusted for socio-demographic and occupational factors was used to estimate the adjusted odds ratio (OR) and 95% confidence interval (CI) for depressive symptoms associated with downsizing, including subgroup analyses.

Results

Among 26,247 Korean workers (mean age: 43.4, men: 47.5%), the prevalence of depressive symptoms was 29.5% (n = 7,751), and the proportion of downsizing was 15.2% (n = 3,978). The prevalence of depressive symptoms was significantly higher among the downsizing group (36.7%, n = 1,460) than among the no-downsizing group (28.3%, n = 6,291). The result of logistic regression revealed a significant association between downsizing and depressive symptoms (adjusted OR [95% CI]: 1.39 [1.29-1.50]), particularly pronounced among high socioeconomic status workers.

Conclusion

This study underscores the significant association between depressive symptoms and organizational downsizing, especially high vulnerability of socioeconomically advantaged and stable workers. These findings highlight the necessity for targeted mental health support and further longitudinal research to clarify the relationship between employment changes and mental health within the Korean workforce.

Stress from early life to adulthood: Is there a protective role of cognitive control?

Early life events can have long-lasting effects that may impact the quality of life into adulthood. The link between childhood adversities and adult mental and physical health is well documented, however, the underlying mechanisms remain poorly understood. Executive functions are assumed to be a key factor in successfully dealing with cognitive-emotional challenges thereby contributing to stress resilience and mental health across the lifespan. Here, we examined whether cognitive control moderates the link between early life adversity and depression. Data was available from a sample of 424 participants aged 20-70 years (Clinicaltrials.gov: NCT05155397). They performed in the Stroop task and behavior as well as frontal theta power were recorded. Negative childhood experiences were assessed with the Childhood Trauma Questionnaire (CTQ), chronic stress was measured with the Trier Inventory for Chronic Stress (TICS) and depression symptoms with Beck's Depression Inventory (BDI). The CTQ predicted symptoms of chronic stress and depression. Regression models pointed to the TICS as a crucial mediator in the relationship between CTQ and BDI. However, parameters of cognitive control demonstrated a rather weak effect as moderators. These results indicate that chronic stress is an important mediator linking childhood trauma to depression but suggest only a limited role for cognitive control.

Repeated exposure to multiple concurrent stressors alters visual processing in the adult posterior parietal cortex

Chronic stress is well known to erode cognitive functions. Yet, our understanding of how repeated stress exposure impacts one of the fundamental bases of cognition: sensory processing, remains limited. The posterior parietal cortex (PPC) is a high order visual region, known for its role in visually guided decision making, multimodal integration, attention, and working memory. Here, we used functional measures to determine how repeated exposure to multiple concurrent stressors (RMS) affects sensory processing in the PPC in adult male mice. A longitudinal experimental design, repeatedly surveying the same population of neurons using in vivo two-photon imaging, revealed that RMS disrupts the balanced turnover of visually responsive cells in layer 2/3 of the PPC. Across the population, RMS-induced changes in visual responsiveness followed a bimodal distribution suggesting idiosyncratic stress effects. In cells that maintained their responsiveness across recording sessions, we found that stress reduced visual response magnitudes and feature selectivity. While we did not observe stress-induced elimination of excitatory synapses, noise correlation statistics indicated that RMS altered visual input to the neuronal population. The impact of RMS was restricted to visually evoked responses and was not evident in neuronal activity associated with locomotion onset. Together, our results indicate that despite no apparent synaptic reorganization, stress exposure in adulthood can disrupt sensory processing in the PPC, with the effects showing remarkable individual variation.

Does Baseline Stress Affect Electrodermal Activity? A Serious-Game-Based Pilot Study

Stress management is crucial for health and well being. Electrodermal activity (EDA) is a promising physiological marker for studying stress. While the detection of stress response to stimuli in the short term using EDA is well-studied, the impact of baseline stress (i.e. averaged daily life stress perceived on the long period) on EDA remains unexplored. This study combines a serious game for stress induction, with simultaneous EDA recording to investigate the relation between baseline stress and the EDA response obtained during gameplay. In a pilot study involving 25 university students, EDA features had moderate correlation (Spearman's ρs ≥0.4, p-value <0.05) with stress perceived by the subject in the previous month and differed significantly between low and moderate baseline stress groups. As a further analysis, shallow learning models trained on EDA features to recognize these two groups achieved ≥ 90.0% accuracy and F1-score in a Leave-One-Subject-Out validation, supporting the initial hypothesis that baseline stress directly affects subjects' EDA.

The Leuven Prolonged Acute Stress Test (L-PAST): A novel paradigm to induce a subjective and glucocorticoid stress response for at least ninety minutes

Laboratory stress tests typically administer stress acutely, ranging from 3 to 15 minutes. However, everyday stressors usually last longer than ten minutes (e.g., examination stressors, work stressors, and social stressors. Moreover, in some studies, it may be relevant to induce stress for a longer period to affect certain psychological or physiological parameters. To this end, we developed a novel stress test that intends to induce psychosocial stress for 90 minutes. The Leuven Prolonged Acute Stress Test (L-PAST) combines physical (hand immersion in cold water), cognitive (mental arithmetic), and psychosocial (social evaluation and feelings of failure) stress elements of two well-known laboratory stress tests, the Maastricht Acute Stress Test (MAST) and the Montreal Imaging Stress Test (MIST). Fifty healthy women were subjected to both the L-PAST and a sham (control) test in a randomized and counterbalanced manner. The stress response was determined by salivary cortisol measurements and assessment of subjective stress ratings at regular time points during the time preceding the stress period (5 min), the stress period (90 min), and the recovery period (35 min). Cognitive reactivity to failure and subjective pain levels were also assessed at various time points. The childhood trauma questionnaire (CTQ) and the perceived stress scale (PSS) were administered prior to the testing phase. As expected, linear mixed models revealed that the stress response was significantly higher during the L-PAST as indicated by a significant time point by condition interaction effect for both the cortisol response (F(10,450)=12.21, p < 0.0001, ηp2=0.11) and the subjective stress response (F(13,637)=13.98, p < 0.0001, ηp2 = 0.12). Moreover, there was a significant time point by condition interaction effect for cognitive reactivity to failure (F(13,637) = 7.97, p < 0.0001, ηp2 = 0.07) and subjective pain (F(13,637) = 38.52, p < 0.0001, ηp2 = 0.27), indicating that the levels were higher during the L-PAST at most stress induction time points. Lastly, higher CTQ scores were associated with higher subjective pain levels during the L-PAST (F(1,44)=6.05, p = 0.02). Collectively, our results confirm the efficacy of the L-PAST in inducing a prolonged subjective as well as cortisol stress response.

Methamphetamine effects in zebrafish (Danio rerio) depend on behavioral endpoint, dose and test session duration

Research using zebrafish (Danio rerio) has begun to provide novel information in many fields, including the behavioral pharmacology of drug use and misuse. There have been limited studies on the effects of methamphetamine in adult zebrafish and the parameters of exposure (dose, test session length) have not been well-documented. Behavior following drug exposure is generally measured during relatively short sessions (6-10 min is common) in a novel tank environment. Many procedural variables (isolation, netting, novel tank) elicit anxiety-like behavior that is most apparent during the initial portion of a test session. This anxiety-like behavior might mask the initial effects of methamphetamine. During longer test sessions, these anxiety-like responses would be expected to habituate and drug effects should become more apparent. To test this idea, we measured several locomotor activity responses for 50-min following a range of methamphetamine doses (0.1-3.0 mg/L via immersion in methamphetamine solution). Methamphetamine failed to alter swimming velocity, distance travelled, or freezing time. In contrast, methamphetamine produced a dose-dependent decrease in time spent in the bottom of the tank, an increase in the number of visits to the top of the tank, and an increase in the number of transitions along the sides of the tank. The effects of methamphetamine were apparent 10-20 min following exposure and generally persisted throughout the session. These findings indicate that longer test sessions are required to measure methamphetamine-induced changes in behavior in zebrafish, as has been shown in other laboratory animals. The results also suggest that anxiety-like responses associated with various procedural aspects (netting, isolation, novel test apparatus) likely interfere with the ability to observe many behavioral effects of methamphetamine in zebrafish. Based on the current results, habituation to testing procedures to reduce anxiety-like behaviors is recommended in determining the effects of methamphetamine in zebrafish.

An Aggressive Interaction Rapidly Increases Brain Androgens in a Male Songbird during the Non-breeding Season

Aggression is a crucial behavior that impacts access to limited resources in different environmental contexts. Androgens synthesized by the gonads promote aggression during the breeding season. However, aggression can be expressed during the non-breeding season, despite low androgen synthesis by the gonads. The brain can also synthesize steroids ("neurosteroids"), including androgens, which might promote aggression during the non-breeding season. Male song sparrows, Melospiza melodia, are territorial year-round and allow the study of seasonal changes in the steroid modulation of aggression. Here, we quantified steroids following a simulated territorial intrusion (STI) for 10 min in wild adult male song sparrows during the breeding and non-breeding seasons. Using liquid chromatography-tandem mass spectrometry (LC-MS/MS), we examined 11 steroids: pregnenolone, progesterone, corticosterone, dehydroepiandrosterone, androstenedione, testosterone, 5α-dihydrotestosterone, 17β-estradiol, 17α-estradiol, estriol, and estrone. Steroids were measured in blood and 10 microdissected brain regions that regulate social behavior. In both seasons, STI increased corticosterone in the blood and brain. In the breeding season, STI had no rapid effects on androgens or estrogens. Intriguingly, in the non-breeding season, STI increased testosterone and androstenedione in several behaviorally relevant regions, but not in the blood, where androgens remained non-detectable. Also in the non-breeding season, STI increased progesterone in the blood and specific brain regions. Overall, rapid socially modulated changes in brain steroid levels are more prominent during the non-breeding season. Brain steroid levels vary with season and social context in a region-specific manner and suggest a role for neuroandrogens in aggression during the non-breeding season.

Racial Differences in Biopsychosocial Pathways to Tobacco and Marijuana Use Among Youth

BACKGROUND

The influence of socioeconomic disparities and multidimensional stressors on youth tobacco and marijuana use is recognized; however, the extent of these effects varies among different racial groups. Understanding the racial differences in the factors influencing substance use is crucial for developing tailored interventions aimed at reducing disparities in tobacco and marijuana use among adolescents.

AIMS

This study aims to explore the differential effects of socioeconomic disparities and multidimensional stressors on tobacco and marijuana use between Black and White adolescents.

METHODS

Utilizing longitudinal data from the Adolescent Brain Cognitive Development (ABCD) study, this research includes a cohort of pre-youth, monitored from the age of 9-10 years for a period of up to 36 months. We examined the impact of various socioeconomic status (SES) indicators and multidimensional stressors, including trauma, financial stress, racial discrimination, and family stress, alongside baseline average cortical thickness and the subsequent initiation of tobacco and marijuana use over the 36-month follow-up.

RESULTS

Overall, 10,777 participants entered our analysis. This included 8263 White and 2514 Black youth. Our findings indicate significant differences in the pathways from SES indicators through stress types to cortical thickness between Black and White youths. Notably, cortical thickness's impact on the future initiation of tobacco and marijuana use was present in both groups.

CONCLUSION

The study suggests that compared to White adolescents, Black adolescents' substance use and associated cortical thickness are less influenced by stress and SES indicators. This discrepancy may be attributed to the compounded effects of racism, where psychosocial mechanisms might be more diminished for Black youth than White youth. These findings support the theory of Minorities' Diminished Returns rather than the cumulative disadvantage or double jeopardy hypothesis, highlighting the need for interventions that address the unique challenges faced by Black adolescents.

Isolation of the differential effects of chronic and acute stress in a manner that is not confounded by stress severity

Firm conclusions regarding the differential effects of the maladaptive consequences of acute versus chronic stress on the etiology and symptomatology of stress disorders await a model that isolates chronicity as a variable for studying the differential effects of acute versus chronic stress. This is because most previous studies have confounded chronicity with the total amount of stress. Here, we have modified the stress-enhanced fear learning (SEFL) protocol, which models some aspects of posttraumatic stress disorder (PTSD) following an acute stressor, to create a chronic variant that does not have this confound. Comparing results from this new protocol to the acute protocol, we found that chronic stress further potentiates enhanced fear-learning beyond the nonassociative enhancement induced by acute stress. This additional component is not observed when the unconditional stimulus (US) used during subsequent fear learning is distinct from the US used as the stressor, and is enhanced when glucose is administered following stressor exposure, suggesting that it is associative in nature. Furthermore, extinction of stressor-context fear blocks this additional associative component of SEFL as well as reinstatement of generalized fear, suggesting reinstatement of generalized fear may underlie this additional SEFL component.

The adaptor protein 2 (AP2) complex modulates habituation and behavioral selection across multiple pathways and time windows

Animals constantly integrate sensory information with prior experience to select behavioral responses appropriate to the current situation. Genetic factors supporting this behavioral flexibility are often disrupted in neuropsychiatric conditions, such as the autism-linked ap2s1 gene which supports acoustically evoked habituation learning. ap2s1 encodes an AP2 endocytosis adaptor complex subunit, although its behavioral mechanisms and importance have been unclear. Here, we show that multiple AP2 subunits regulate acoustically evoked behavior selection and habituation learning in zebrafish. Furthermore, ap2s1 biases escape behavior choice in sensory modality-specific manners, and broadly regulates action selection across sensory contexts. We demonstrate that the AP2 complex functions acutely in the nervous system to modulate acoustically evoked habituation, suggesting several spatially and/or temporally distinct mechanisms through which AP2 regulates escape behavior selection and performance. Altogether, we show the AP2 complex coordinates action selection across diverse contexts, providing a vertebrate model for ap2s1's role in human conditions including autism spectrum disorder.

Social media does not elicit a physiological stress response as measured by heart rate and salivary cortisol over 20-minute sessions of cell phone use

The pervasive use of social media has raised concerns about its potential detrimental effects on physical and mental health. Others have demonstrated a relationship between social media use and anxiety, depression, and psychosocial stress. In light of these studies, we examined physiological indicators of stress (heart rate to measure autonomic nervous system activation and cortisol to assess activity of the hypothalamic-pituitary-adrenal axis) associated with social media use and investigated possible moderating influences of sex, age, and psychological parameters. We collected physiological data from 59 subjects ranging in age from 13 to 55 across two cell phone treatments: social media use and a pre-selected YouTube playlist. Heart rate was measured using arm-band heart rate monitors before and during cell phone treatments, and saliva was collected for later cortisol analysis (by enzyme immunoassay) before and after each of the two cell phone treatments. To disentangle the effects of cell phone treatment from order of treatment, we used a crossover design in which participants were randomized to treatment order. Our study uncovered a significant period effect suggesting that both heart rate and cortisol decreased over the duration of our experiment, irrespective of the type of cell phone activity or the order of treatments. There was no indication that age, sex, habits of social media use, or psychometric parameters moderated the physiological response to cell phone activities. Our data suggest that 20-minute bouts of social media use or YouTube viewing do not elicit a physiological stress response.

The unconditioned fear response in vertebrates deficient in dystrophin

Dystrophin loss due to mutations in the Duchenne muscular dystrophy (DMD) gene is associated with a wide spectrum of neurocognitive comorbidities, including an aberrant unconditioned fear response to stressful/threat stimuli. Dystrophin-deficient animal models of DMD demonstrate enhanced stress reactivity that manifests as sustained periods of immobility. When the threat is repetitive or severe in nature, dystrophinopathy phenotypes can be exacerbated and even cause sudden death. Thus, it is apparent that enhanced sensitivity to stressful/threat stimuli in dystrophin-deficient vertebrates is a legitimate cause of concern for patients with DMD that could impact neurocognition and pathophysiology. This review discusses our current understanding of the mechanisms and consequences of the hypersensitive fear response in preclinical models of DMD and the potential challenges facing clinical translatability.

Effect of recurrent task-induced acute stress on task performance, vagally mediated heart rate variability, and task-evoked pupil response

Advances in wearable sensor technologies can be leveraged to investigate behavioral and physiological responses in task-induced stress environments. Reliable and valid multidimensional assessments are required to detect stress given its multidimensional nature. This study investigated the effect of recurrent task-induced acute stress on task performance, vagally mediated heart variability measures (vmHRV) and task-evoked pupillary response (TEPR). Task performance, vmHRV measures, and TEPR were collected from 32 study participants while they performed a computer-based task in a recurrent task-induced acute stress environment. Mixed-effects modeling was used to assess the sensitivity of each outcome variable to experimental conditions. Repeated measures correlation tests were used to examine associations between outcome variables. Task performance degraded under stress. vmHRV measures were lower in the stress conditions relative to the no stress conditions. TEPR was found to be higher in the stress conditions compared to the no stress conditions. Task performance was negatively associated with the vmHRV measures, and degraded task performance was linked to increased TEPR in the stress conditions. There were positive associations between vmHRV measures. TEPR was negatively associated with vmHRV measures. Although task-induced stress degrades task performance, recurrent exposure to that stress could alter this effect via habituation. Further, our findings suggest that vmHRV measures and TEPR are sensitive enough to quantify psychophysiological responses to recurrent task-induced stress.

Asian elephant calf physiology and mahout perspectives during taming in Myanmar

A quarter of Asian elephants are captive, with greater than 90% of these tamed and cared for by handlers (mahouts) in Asia. Although taming is a much-discussed welfare issue, no studies to our knowledge have empirically assessed its impact on calves, and dialogue surrounding taming often lacks perspectives of those involved. Here, we interviewed mahouts involved in taming and monitored five physiological measures (faecal glucocorticoid metabolites (FGMs), serum cortisol, glucose, creatine kinase (CK) and heterophil:lymphocyte (H:L)) over the first 10 days of taming and following six months in 41 calves undergoing taming and 16 control individuals. These measures assess the duration and intensity of stress during taming. Interviews suggested mahouts had major concerns for their safety when discussing changing taming practices, an important consideration for future management. Calf physiological measures were elevated by 50-70% (FGMs/cortisol/glucose), 135% (H:L) and greater than 500% (CK) over the first few days of taming, indicative of elevated stress, not seen to the same extent in control adults. Some measures stabilized sooner (glucose/cortisol/CK/FGM: 7-10 days) than others (H:L: one-two months), indicating mostly acute stress. Our findings inform the welfare of approximately 15 000 captive elephants around the world. Future studies should compare taming in different populations and consider calf and mahout welfare.

Sex Differences in the Relationship Between Nucleus Accumbens Volume and Youth Tobacco or Marijuana Use Following Stressful Life Events

Background

Exposure to stressful life events (SLEs) can upset balance and affect the healthy brain development of children and youths. These events may influence substance use by altering brain reward systems, especially the nucleus accumbens (NAc), which plays a key role in motivated behaviors and reward processing. The interaction between sensitization to SLEs, depression, and substance use might vary between male and female youths, potentially due to differences in how each sex responds to SLEs.

Aims

This study aims to examine the effect of sex on the relationship between SLEs, Nucleus Accumbens activity, and substance use in a nationwide sample of young individuals.

Methods

We utilized data from the Adolescent Brain Cognitive Development study (ABCD), a longitudinal study of pre-adolescents aged 9-10 years, comprising 11,795 participants tracked over 36 months. Structured interviews measuring SLEs were conducted using the Kiddie Schedule for Affective Disorders and Schizophrenia (K-SADS). Initial linear regression analyses explored if SLEs could predict volumes of the right and left NAc. Subsequently, Cox regression models were used to investigate how SLEs and NAc volume might predict the initiation of tobacco and marijuana use, with the analysis stratified by sex to address potential sex differences.

Results

Our findings reveal that SLEs significantly predicted marijuana use in males but not in females, and tobacco use was influenced by SLEs in both sexes. A higher number of SLEs was linked with decreased left NAc volume in males, a trend not seen in females. The right NAc volume did not predict substance use in either sex. However, volumes of both the right and left NAc were significant predictors of future tobacco use, with varying relationships across sexes. In females, an inverse relationship was observed between both NAc volumes and the risk of tobacco use. In contrast, a positive correlation existed between the left NAc volume and tobacco and marijuana use in males, with no such relationship for females.

Conclusion

This study underscores that the associations between SLEs, NAc volume, and subsequent substance use are influenced by a nuanced interplay of sex, brain hemisphere, and substance type.

Circadian Influence on Acute Stress-induced Changes in Cortico-limbic Endocannabinoid Levels in Adult Male Rats

The endocannabinoid (eCB) system plays an important role in regulating the stress response, including glucocorticoid release and the generation of avoidance behaviour. Its two major ligands, 2-arachidonoylglycerol (2-AG) and N-arachidonoylethanolamine (anandamide; AEA), are dynamically influenced by psychological stress to gate the generation of the stress response and facilitate recovery upon stress termination. Many biological systems exhibit circadian "daily" rhythms, including glucocorticoids and endocannabinoids, and the behavioural and endocrine impact of stress is modulated by the time of day. Nonetheless, most preclinical experiments investigating the interaction between stress and endocannabinoids occur in the light, "inactive" phase. We therefore tested if circadian phase influences stress-induced changes in eCB levels in the hippocampus (HIP), prefrontal cortex (PFC), and amygdala (AMY). Adult male rats were exposed to 15 min swim stress or immediately euthanized, and brains were collected. Testing occurred either early in the light or early in the dark phase of their cycle to compare circadian effects. We found that overall, stress decreased AEA in the AMY and HIP, with an effect in the PFC dependent on the time of day. Conversely, stress increased 2-AG in the AMY, with an effect in the PFC and HIP dependent on the time of day. This suggests that stress has a similar overall impact on eCB levels regardless of circadian phase, but that subtle differences may occur depending on the brain region, especially the PFC.

Neuronal tuning to threat exposure remains stable in the mouse prefrontal cortex over multiple days

Intense threat elicits action in the form of active and passive coping. The medial prefrontal cortex (mPFC) executes top-level control over the selection of threat coping strategies, but the dynamics of mPFC activity upon continuing threat encounters remain unexplored. Here, we used 1-photon calcium imaging in mice to probe the activity of prefrontal pyramidal cells during repeated exposure to intense threat in a tail suspension (TS) paradigm. A subset of prefrontal neurons displayed selective activation during TS, which was stably maintained over days. During threat, neurons showed specific tuning to active or passive coping. These responses were unrelated to general motion tuning and persisted over days. Moreover, the neural manifold traversed by low-dimensional population activity remained stable over subsequent days of TS exposure and was preserved across individuals. These data thus reveal a specific, temporally, and interindividually conserved repertoire of prefrontal tuning to behavioral responses under threat.

Static electric field exposure decreases white blood cell count in peripheral blood through activating hypothalamic-pituitary-adrenal axis

With the development of ultra-high-voltage (UHV) direct-current (DC) transmission, the health risk from the static electric field (SEF) generated by UHV DC transmission lines has drawn public attention. To investigate the effect of SEF exposure on white blood cell (WBC) count, mice were exposed to 56.3 kV/m SEF. Results revealed that total WBC count and lymphocyte count significantly decreased and serum levels of corticotropin-releasing hormone, adrenocorticotropic hormone and corticosterone (CORT) significantly increased after the exposure of 7d and 14d. All indices above recovered after the exposure of 21d. Analysis showed that the exposure of 7d and 14d could activate hypothalamic-pituitary-adrenal (HPA) axis. The increased CORT could bind to the glucocorticoid receptor (GR) in lymphocytes, and then promote the migration and apoptosis of lymphocytes. After the exposure of 21d, the magnitude of HPA axis activation declined through CORT-mediated negative feedback and the regulation of stress-related neural circuitry, so WBC count recovered.

The effects of early-life and intergenerational stress on the brain

Stress experienced during ontogeny can have profound effects on the adult phenotype. However, stress can also be experienced intergenerationally, where an offspring's phenotype can be moulded by stress experienced by the parents. Although early-life and intergenerational stress can alter anatomy, physiology, and behaviour, nothing is known about how these stress contexts interact to affect the neural phenotype. Here, we examined how early-life and intergenerational stress affect the brain in eastern fence lizards (Sceloporus undulatus). Some lizard populations co-occur with predatory fire ants, and stress from fire ant attacks exerts intergenerational physiological and behavioural changes in lizards. However, it is unclear if intergenerational stress, or the interaction between intergenerational and early-life stress, modulates the brain. To test this, we captured gravid females from fire ant invaded and uninvaded populations, and subjected offspring to three early-life stress treatments: (1) fire ant attack, (2) corticosterone, or (3) a control. Corticosterone and fire ant attack decreased some aspects of the neural phenotype while population of origin and the interaction of early-life stress and population had no effects on the brain. These results suggest that early-life stressors may better predict adult brain variation than intergenerational stress in this species.

Hemokinin-1 is a mediator of chronic restraint stress-induced pain

The Tac4 gene-derived hemokinin-1 (HK-1) binds to the NK1 receptor, similarly to Substance P, and plays a role in acute stress reactions and pain transmission in mice. Here we investigated Tac4 mRNA expression in stress and pain-related regions and its involvement in chronic restraint stress-evoked behavioral changes and pain using Tac4 gene-deleted (Tac4-/-) mice compared to C57Bl/6 wildtypes (WT). Tac4 mRNA was detected by in situ hybridization RNAscope technique. Touch sensitivity was assessed by esthesiometry, cold tolerance by paw withdrawal latency from 0°C water. Anxiety was evaluated in the light-dark box (LDB) and open field test (OFT), depression-like behavior in the tail suspension test (TST). Adrenal and thymus weights were measured at the end of the experiment. We found abundant Tac4 expression in the hypothalamic-pituitary-adrenal axis, but Tac4 mRNA was also detected in the hippocampus, amygdala, somatosensory and piriform cortices in mice, and in the frontal regions and the amygdala in humans. In Tac4-/- mice of both sexes, stress-induced mechanical, but not cold hyperalgesia was significantly decreased compared to WTs. Stress-induced behavioral alterations were mild or absent in male WT animals, while significant changes of these parameters could be detected in females. Thymus weight decrease can be observed in both sexes. Higher baseline anxiety and depression-like behaviors were detected in male but not in female HK-1-deficient mice, highlighting the importance of investigating both sexes in preclinical studies. We provided the first evidence for the potent nociceptive and stress regulating effects of HK-1 in chronic restraint stress paradigm. Identification of its targets might open new perspectives for therapy of stress-induced pain.

Best Parameters of Heart Rate Variability for Assessing Autonomic Responses to Brief Rectal Distention in Patients with Irritable Bowel Syndrome

Heart rate variability (HRV) has been used to measure autonomic nervous system (ANS) activity noninvasively. The purpose of this study was to identify the most suitable HRV parameters for ANS activity in response to brief rectal distension (RD) in patients with Irritable Bowel Syndrome (IBS). IBS patients participated in a five-session study. During each visit, an ECG was recorded for 15 min for baseline values and during rectal distension. For rectal distension, a balloon was inflated in the rectum and the pressure was increased in steps of 5 mmHg for 30 s; each distension was followed by a 30 s rest period when the balloon was fully deflated (0 mmHg) until either the maximum tolerance of each patient was reached or up to 60 mmHg. The time-domain, frequency-domain and nonlinear HRV parameters were calculated to assess the ANS activity. The values of each HRV parameter were compared between baseline and RD for each of the five visits as well as for all five visits combined. The sensitivity and robustness/reproducibility of each HRV parameter were also assessed. The parameters included the Sympathetic Index (SI); Root Mean Square of Successive Differences (RMSSD); High-Frequency Power (HF); Low-Frequency Power (LF); Normalized HF Power (HFn); Normalized LF Power (LFn); LF/HF; Respiratory Sinus Arrhythmia (RSA); the Poincare Plot's SD1, SD2 and their ratio; and the pNN50, SDSD, SDNN and SDNN Index. Data from 17 patients were analyzed and compared between baseline and FD and among five sessions. The SI was found to be the most sensitive and robust HRV parameter in detecting the ANS response to RD. Out of nine parasympathetic parameters, only the SDNN and SDNN Index were sensitive enough to detect the parasympathetic modulation to RD during the first visit. The frequency-domain parameters did not show any change in response to RD. It was also observed that the repetitive RD in IBS patients resulted in a decreased autonomic response due to habituation because the amount of change in the HRV parameters was the highest during the first visit but diminished during subsequent visits. In conclusion, the SI and SDNN/SDNN Index are most sensitive at assessing the autonomic response to rectal distention. The autonomic response to rectal distention diminishes in repetitive sessions, demonstrating the necessity of randomization for repetitive tests.

Dispositional Active Coping Predicts Patterns of Adolescents' Cortisol Responsivity in the Context of School-related Stressors

OBJECTIVE

The goal of this study was to examine the direct and conditional effects of active coping and prior exposure to school-related stressors on cortisol reactivity and recovery in response to an academically salient, social stress task.

METHOD

Participants included N= 758 adolescents (50% male; M age = 12.03 years, SD = .49) enrolled in the 7th grade in Title 1 middle schools. Adolescents were predominantly ethnic minorities (62% Hispanic, 12% non-Hispanic White, 11% non-Hispanic Black, 7% Native American, and 8% "other"). Youth completed self-reported assessments of their dispositional use of active coping strategies, prior exposure to school hassles, pubertal status, medication use, and relevant demographic information. In addition, youth engaged in an academically salient group public speaking task adapted for adolescents and provided salivary cortisol sample pre-task, immediately post-task, 15-, and 30-minutes post-task.

RESULTS

Results from piecewise latent growth curve modeling revealed that active coping independently predicted lower cortisol reactivity to the stress task. Furthermore, active coping was associated with slower cortisol recovery when adolescents reported not having experienced any school hassles in the past three months and faster recovery when having experienced several school hassles in the past three months. Results from multinomial logistic regressions revealed that greater use of active coping strategies was less likely to predict a hyper-reactive pattern of cortisol responding compared to other patterns.

CONCLUSION

Findings provide support for active coping as a way to promote adaptive physiological responding to school-related stressors among ethnically diverse youth residing in low-income communities.

Tools for photomotor response assay standardization in ecotoxicological studies: Example of exposure to gentamicin in the freshwater planaria Schmidtea mediterranea

Photomotor response assay (PMR) is very useful in an ecotoxicological context because it allows evaluation of behavioral response to potential toxic compounds. However, a lack of procedure standardization makes results comparison difficult between labs and organisms. Here, we aimed to propose five different tools to standardize the PMR procedure so that it may be applied to all model species, regarding: (1) the minimum total sample size, (2) the acclimation period, (3) the number and duration of light and dark phases alternation, (4) the measured behavior, and (5) the statistical analysis. As an example of procedure application, we analyzed the effect of an exposure to the antibiotic gentamicin on the locomotion behavior during PMR in an invertebrate species: the asexual freshwater planaria Schmidtea mediterranea. We encourage future studies using PMR to follow these five tools to improve data analysis and results comparability.

Integrative miRNA-mRNA network analysis to identify crucial pathways of salinity adaptation in brain transcriptome of Labeo rohita

Introduction: Brain being the master regulator of the physiology of animal, the current study focuses on the gene expression pattern of the brain tissue with special emphasis on regulation of growth, developmental process of an organism and cellular adaptation of Labeo rohita against unfavourable environmental conditions. Methods: RNA-seq study was performed on collected brain samples at 8ppt salt concentration and analyzed for differential gene expression, functional annotation and miRNA-mRNA regulatory network. Results: We found that 2450 genes were having significant differential up and down regulation. The study identified 20 hub genes based on maximal clique centrality algorithm. These hub genes were mainly involved in various signaling pathways, energy metabolism and ion transportation. Further, 326 up and 1214 down regulated genes were found to be targeted by 7 differentially expressed miRNAs i.e., oni-miR-10712, oni-miR-10736, ssa-miR-221-3p, ssa-miR-130d-1-5p, ssa-miR-144-5p and oni-miR-10628. Gene ontology analysis of these differentially expressed genes led to the finding that these genes were involved in signal transduction i.e., calcium, FOXO, PI3K-AKT, TGF-β, Wnt and p53 signalling pathways. Differentially expressed genes were also involved in regulation of immune response, environmental adaptation i.e., neuroactive ligand-receptor interaction, ECM-receptor interaction, cell adhesion molecules and circadian entrainment, osmoregulation and energy metabolism, which are critical for salinity adaptation. Discussion: The findings of whole transcriptomic study on brain deciphered the miRNA-mRNA interaction patterns and pathways associated with salinity adaptation of L. rohita.

Alterations of pain pathways by experimental sleep disturbances in humans: central pain-inhibitory, cyclooxygenase, and endocannabinoid pathways

STUDY OBJECTIVES

There is strong evidence that sleep disturbances are an independent risk factor for the development of chronic pain conditions. The mechanisms underlying this association, however, are still not well understood. We examined the effect of experimental sleep disturbances (ESDs) on three pathways involved in pain initiation/resolution: (1) the central pain-inhibitory pathway, (2) the cyclooxygenase (COX) pathway, and (3) the endocannabinoid (eCB) pathway.

METHODS

Twenty-four healthy participants (50% females) underwent two 19-day long in-laboratory protocols in randomized order: (1) an ESD protocol consisting of repeated nights of short and disrupted sleep with intermittent recovery sleep; and (2) a sleep control protocol consisting of nights with an 8-hour sleep opportunity. Pain inhibition (conditioned pain modulation, habituation to repeated pain), COX-2 expression at monocyte level (lipopolysaccharide [LPS]-stimulated and spontaneous), and eCBs (arachidonoylethanolamine, 2-arachidonoylglycerol, docosahexaenoylethanolamide [DHEA], eicosapentaenoylethanolamide, docosatetraenoylethanolamide) were measured every other day throughout the protocol.

RESULTS

The central pain-inhibitory pathway was compromised by sleep disturbances in females, but not in males (p < 0.05 condition × sex effect). The COX-2 pathway (LPS-stimulated) was activated by sleep disturbances (p < 0.05 condition effect), and this effect was exclusively driven by males (p < 0.05 condition × sex effect). With respect to the eCB pathway, DHEA was higher (p < 0.05 condition effect) in the sleep disturbance compared to the control condition, without sex-differential effects on any eCBs.

CONCLUSIONS

These findings suggest that central pain-inhibitory and COX mechanisms through which sleep disturbances may contribute to chronic pain risk are sex specific, implicating the need for sex-differential therapeutic targets to effectively reduce chronic pain associated with sleep disturbances in both sexes.

CLINICAL TRIALS REGISTRATION

NCT02484742: Pain Sensitization and Habituation in a Model of Experimentally-induced Insomnia Symptoms. https://clinicaltrials.gov/ct2/show/NCT02484742.

Determination of steady-state transcriptome modifications associated with repeated homotypic stress in the rat rostral posterior hypothalamic region

Chronic stress is epidemiologically correlated with physical and psychiatric disorders. Whereas many animal models of chronic stress induce symptoms of psychopathology, repeated homotypic stressors to moderate intensity stimuli typically reduce stress-related responses with fewer, if any, pathological symptoms. Recent results indicate that the rostral posterior hypothalamic (rPH) region is a significant component of the brain circuitry underlying response reductions (habituation) associated with repeated homotypic stress. To test whether posterior hypothalamic transcriptional regulation associates with the neuroendocrine modifications induced by repeated homotypic stress, RNA-seq was performed in the rPH dissected from adult male rats that experienced either no stress, 1, 3, or 7 stressful loud noise exposures. Plasma samples displayed reliable increases of corticosterone in all stressed groups, with the smallest increase in the group exposed to 7 loud noises, indicating significant habituation compared to the other stressed groups. While few or no differentially expressed genes were detected 24-h after one or three loud noise exposures, relatively large numbers of transcripts were differentially expressed between the group exposed to 7 loud noises when compared to the control or 3-stress groups, respectively, which correlated with the corticosterone response habituation observed. Gene ontology analyses indicated multiple significant functional terms related to neuron differentiation, neural membrane potential, pre- and post-synaptic elements, chemical synaptic transmission, vesicles, axon guidance and projection, glutamatergic and GABAergic neurotransmission. Some of the differentially expressed genes (Myt1l, Zmat4, Dlx6, Csrnp3) encode transcription factors that were independently predicted by transcription factor enrichment analysis to target other differentially regulated genes in this study. A similar experiment employing in situ hybridization histochemical analysis in additional animals validated the direction of change of the 5 transcripts investigated (Camk4, Gabrb2, Gad1, Grin2a and Slc32a) with a high level of temporal and regional specificity for the rPH. In aggregate, the results suggest that distinct patterns of gene regulation are obtained in response to a repeated homotypic stress regimen; they also point to a significant reorganization of the rPH region that may critically contribute to the phenotypic modifications associated with repeated homotypic stress habituation.

Chronic Pain and Affective Experiences Associated with Daily Stressors and Uplifts

People with chronic pain often report greater reactivity to stress than those without pain. This finding is consistent with the kindling hypothesis, which states that continued exposure to stressors only heightens negative affect and dampens positive affect. Yet, people with chronic pain may also respond more positively to enjoyable activities, or uplifts, as well. Chronic pain is related to lower levels of well-being, and the fragility of positive affect model explains how individuals with lower levels of well-being often exhibit stronger, more positive responses to daily uplifts than their less distressed peers. Our study used the National Study of Daily Experiences to assess daily stressors, positive uplifts, and positive and negative affect across eight days among those with and without chronic pain. Participants (nChronicPain=658, nNoPain=1,075) were predominately Non-Hispanic White (91%), 56% female, and averaged 56 years old. Results revealed that people with chronic pain had lower levels of daily positive affect and higher levels of negative affect, yet the two groups did not vary in their stressor-related negative and positive affect. In contrast, having chronic pain was related to a greater increase in positive affect and greater decreases in negative affect on days with positive uplifts. Findings suggest that intervention efforts focusing on uplifts may be particularly helpful for people who report chronic pain.

GPCR-mediated calcium and cAMP signaling determines psychosocial stress susceptibility and resiliency

Chronic stress increases the risk of developing psychiatric disorders, including mood and anxiety disorders. Although behavioral responses to repeated stress vary across individuals, the underlying mechanisms remain unclear. Here, we perform a genome-wide transcriptome analysis of an animal model of depression and patients with clinical depression and report that dysfunction of the Fos-mediated transcription network in the anterior cingulate cortex (ACC) confers a stress-induced social interaction deficit. Critically, CRISPR-Cas9-mediated ACC Fos knockdown causes social interaction deficits under stressful situation. Moreover, two classical second messenger pathways, calcium and cyclic AMP, in the ACC during stress differentially modulate Fos expression and regulate stress-induced changes in social behaviors. Our findings highlight a behaviorally relevant mechanism for the regulation of calcium- and cAMP-mediated Fos expression that has potential as a therapeutic target for psychiatric disorders related to stressful environments.