Stress-related Behaviors Research Articles

Lifetime stressor exposure, eating expectancy, and acute social stress-related eating behavior: A pre-registered study of the emotional eating cycle

Eating behaviors in response to acute stressors are highly variable: whereas many individuals eat more following stressors, others eat less or show no change in food consumption. Understanding factors that predict individual differences in eating behaviors may help elucidate the psychosocial mechanisms underlying obesity, yet few experimental studies on this topic have been conducted to date. To address this issue, we conducted the present pre-registered study, where we investigated how lifetime stressor exposure moderates the extent to which eating expectancies enhance the learned association between stress-induced negative affect and snack intake. Participants were 44 women (30% non-White) between 18 and 50 years old (M = 27.9), with a mean body mass index of 25.6, who completed assessments of lifetime stressor exposure, eating behaviors, and eating expectancies (eating helps manage negative affect); in a subsequent visit, they were given snacks after an acute social stress task (TSST). The moderated moderation model (PROCESS model 3) yielded a significant three-way interaction. When eating expectancies were high, acute social stress-induced negative affect predicted greater M&M intake for women with very high total lifetime stressor exposure but less M&M intake for women with fewer lifetime stressors. These data thus highlight how lifetime stressor exposure interacts with eating expectancies and acute stress-induced negative affect to predict eating behavior. Replications in larger samples may help explain variability in stress-eating as well as how lifetime stressors contribute to obesity.

Limosilactobacillus reuteri administration alters the gut-brain-behavior axis in a sex-dependent manner in socially monogamous prairie voles.

Research on the role of gut microbiota in behavior has grown dramatically. The probiotic L. reuteri can alter social and stress-related behaviors - yet, the underlying mechanisms remain largely unknown. Although traditional laboratory rodents provide a foundation for examining the role of L. reuteri on the gut-brain axis, they do not naturally display a wide variety of social behaviors. Using the highly-social, monogamous prairie vole (Microtus ochrogaster), we examined the effects of L. reuteri administration on behaviors, neurochemical marker expression, and gut-microbiome composition. Females, but not males, treated with live L. reuteri displayed lower levels of social affiliation compared to those treated with heat-killed L. reuteri. Overall, females displayed a lower level of anxiety-like behaviors than males. Live L. reuteri-treated females had lower expression of corticotrophin releasing factor (CRF) and CRF type-2-receptor in the nucleus accumbens, and lower vasopressin 1a-receptor in the paraventricular nucleus of the hypothalamus (PVN), but increased CRF in the PVN. There were both baseline sex differences and sex-by-treatment differences in gut microbiome composition. Live L. reuteri increased the abundance of several taxa, including Enterobacteriaceae, Lachnospiraceae NK4A136, and Treponema. Interestingly, heat-killed L. reuteri increased abundance of the beneficial taxa Bifidobacteriaceae and Blautia. There were significant correlations between changes in microbiota, brain neurochemical markers, and behaviors. Our data indicate that L. reuteri impacts gut microbiota, gut-brain axis and behaviors in a sex-specific manner in socially-monogamous prairie voles. This demonstrates the utility of the prairie vole model for further examining causal impacts of microbiome on brain and behavior.

A bad time for kids in lockdown: The relationship between negative pandemic events, parenting stress, and maltreatment related parenting behaviors

BackgroundTo date, several studies have shown that parenting stress, a kind of role strain, is related to child maltreatment. However, few studies have examined how the effects of crises, such as negative pandemic-related events on the household, may be related to parenting stress and maltreatment-related behavior. ObjectiveThis study examines the impact of negative Covid-related events on parenting stress and parenting behaviors during a period that was likely to have been a peak point of stress for many parents during the Covid-19 pandemic. ParticipantsRespondents were female caregivers (N = 720) of children under the age of six located in the Midwestern United States. ResultsThree or more Covid-related impacts on the household were positively associated with parenting stress (B = 0.177, p < 0.05). Parenting stress fully mediated the weak relationship between these impacts and maltreatment-related behavior. Mothers of different employment statuses, including those who were recently laid off or who chose to stay at home, did not have significantly different probabilities of parenting stress or maltreatment-related behaviors. Contrary to theory, similar null results were found across other socio-demographic variables. ConclusionsThese null findings suggest that crises have effects that encompass family systems, potentially raising parenting stress levels in many groups that are typically considered low-risk for child maltreatment. Results have implications for scholarship on parenting stress, the targeting of social supports to mothers of young children, and rapid interventions to reduce stress, such as the stimulus check relief program.

Access to Multiple Habitats Improves Welfare: A Case Study of Two Zoo-Housed Black Bears (Ursus americanus)

Using various forms of enrichment, animal care specialists encourage species-specific behaviors and discourage stereotypic behaviors. Within the zoo community, bears (Ursids spp.) are commonly housed, yet are prone to exhibiting stress-related behaviors. Here, we assess the effect of access to multiple habitats, including areas of off guest view, on the welfare of two American black bears (U. americanus) housed at the North Carolina Zoo. In this study, we looked at two behaviors, pacing and foraging to represent negative and positive welfare indicators. We performed logistic regressions to model the effect of access on these behaviors. Because having an animal visible to guests is important to consider when creating management plans, we also explored the effect of access on the bears’ visibility. We found that full access reduced the likelihood of pacing by an average of 13% and increased the likelihood of foraging by an average of 5%. Access to multiple areas reduced the probability of visibility by 57% for one individual but did not impact visibility of the other bear. This case study suggests the value of access to zoo animal welfare and should incite future research aimed at exploring the effects of access on various behavioral outcomes.

Enrichment of intrinsically disordered residues in ohnologs facilitates abiotic stress resilience in Brassica rapa

Arabidopsis thaliana and Brassica rapa are in the same evolutionary lineage, although the latter experienced an additional whole genome triplication event. Therefore, it would be intriguing to investigate the traits that gene duplication imposes to mediate plant stress tolerance. Here, we noticed that B. rapa abiotic stress resistance (ASR) genes which code at least one stress responsive domain have a significantly higher number of paralogs than A. thaliana. Analysing the disordered content of the ASR genes in both species, we found that intrinsically disordered residues (IDR) are specifically enriched in whole genome duplication (WGD) derived paralogs. Subsequently, domain similarity analysis between WGD pairs of both species has revealed that majority of WGD pairs in B. rapa did not share domains with each other. Furthermore, domain enrichment analysis has shown that B. rapa paralogs contain 36 distinct stress responsive enriched domains, significantly higher than A. thaliana paralogs. Next, we performed MSA to investigate the domain conservation between orthologs and ohnologs pairs, we found that 80.13% of B. rapa ohnologs acquire new domains, depicting the fact that ohnologs play a significant role in stress-related behaviours. The average IDR content of the ohnologs enriching new domains after gene duplication in B. rapa (0.19), is also significantly higher than A. thaliana (0.04). Interestingly, we also found that all of these attributes i.e., exhibiting higher number of WGD paralogs and enhancement of IDR in ASR genes of B. rapa compared to A. thaliana is exclusive for ASR genes only. No such significant differences were observed in randomly selected non-ASR genes between the two species. Together these results provide strong support for the hypothesis that augmentation of IDR content followed by a whole genome duplication event imposes the stress resistance potentiality in B. rapa. This research will shed light on the mechanism of how B. rapa is able to successfully adapt to stress over the evolutionary timescale.

Enriching Lives in Captivity: A Case Study on Stress Reduction in Leptailurus serval through Environmental Enrichment

This case report describes the application of environmental enrichment in a Leptailurus serval with the aim of reducing stress and stereotypic behaviors observed in the animal. The study was conducted on a private property in São Paulo, Brazil, for a period of four months. The feline was housed in an enclosure measuring 46.4 m2, which included sand substrate, grassy area, trees, a pond, a bed, a den, and platforms. Prior to the study, both normal behaviors and stress-related behaviors were observed. Environmental enrichment actions were planned, involving olfactory, physical, and feeding stimuli. Natural odors such as catnip, chamomile, mint, lemon balm, anise, and high-quality hay were used. These odors were presented to the animal through sachets, toys, and structures scattered throughout the enclosure. Portions of raw chicken were hidden to stimulate hunting behavior. The results showed different levels of interaction between the animal and the environmental enrichment stimuli. There was greater interest and interaction with catnip, chamomile, and mint, while lemon balm and anise resulted in low interaction. High-quality hay generated intense interaction. In conclusion, environmental enrichment provided sensory, physical, and feeding stimuli to the Leptailurus serval, contributing to its well-being, reducing stress, and minimizing stereotypic behaviors. These practices simulated aspects of the animal's natural environment, enriching its life in captivity and promoting its physical and mental health.

Gut indigenous Ruminococcus gnavus alleviates constipation and stress-related behaviors in mice with loperamide-induced constipation.

Refractory constipation is the most severe form of constipation, and its etiology remains unknown. The symptoms of constipation occur repeatedly, which brings great pain to the patient's body and psychology. Accumulating studies suggest that constipation patients present a significant dysbiosis of the gut microbiota compared with healthy individuals. In this study, we analyzed the gut microbiota composition of fresh feces and accumulated feces (old feces) of patients with refractory constipation and found that there was a significant difference between them. Through a mouse model of loperamide-induced constipation, it was proved that the old feces of patients with refractory constipation could aggravate the constipation symptoms in mice, while the fresh feces could alleviate the symptoms, which is consistent with the effect of feces from healthy volunteers in a mouse model of loperamide-induced constipation. We identified an indigenous strain Ruminococcus gnavus (R. gnavus), which is highly enriched in the fresh feces of patients with refractory constipation, and found that oral administration of R. gnavus could effectively improve the constipation symptoms in mice with constipation induced by loperamide and fecal bacteria transplanted from patients with constipation and significantly improve the stress-related behaviors of mice. This result may be related to the regulation of intestinal muc2, c-kit, sert and other gene expression by R. gnavus and the control of somatostatin (SS) and motilin (MTL) production. Our results suggest that gut microbe intervention with indigenous strains such as R. gnavus is a potential and promising alternative for the treatment of constipation, especially for refractory constipation.

Sources of Stress and Coping Behaviors among Nursing Students Throughout Their First Clinical Training.

Clinical training allows nursing students to acquire and strengthen their psychomotor abilities, which is an important component of nursing education. The clinical components of nursing training programs were much more demanding than the academic ones. The purpose of this study was to examine sources of stress-related and coping behaviors during first clinical training among nursing students in the Arab American University. The study was cross-sectional and conducted with a convenience sample of 266 participants of nursing students. Data collection was performed by "Perceived Stress Scale and the Coping Behavior Inventory." The data were analyzed by using the descriptive, that is, frequency and percentage, mean, and standard deviation. The results revealed that the perceived stress mean was 41.2 (SD = 19.5). The main stressors were taking care of the patients (M = 11.4 ± 0.85) and teachers and nursing staff (M = 8.32 ± 5.3). Coping behaviors mean was (M = 29.0 ± 15.2). The main coping behavior was problem-solving (M = 9.5 ± 5.6). The study confirmed that students perceived moderate levels of stress in their first clinical training, and the most common sources of stress were taking care of the patients and teachers and nursing staff. However, the main coping behavior was problem-solving.

Lateral Septum Somatostatin Neurons are Activated by Diverse Stressors

The lateral septum (LS) is a forebrain structure that has been implicated in a wide range of behavioral and physiological responses to stress. However, the specific populations of neurons in the LS that mediate stress responses remain incompletely understood. Here, we show that neurons in the dorsal lateral septum (LSd) that express the somatostatin gene (hereafter, LSdSst neurons) are activated by diverse stressors. Retrograde tracing from LSdSst neurons revealed that these neurons are directly innervated by neurons in the locus coeruleus (LC), the primary source of norepinephrine well-known to mediate diverse stress-related functions in the brain. Consistently, we found that norepinephrine increased excitatory synaptic transmission onto LSdSst neurons, suggesting the functional connectivity between LSdSst neurons and LC noradrenergic neurons. However, optogenetic stimulation of LSdSst neurons did not affect stress-related behaviors or autonomic functions, likely owing to the functional heterogeneity within this population. Together, our findings show that LSdSst neurons are activated by diverse stressors and suggest that norepinephrine released from the LC may modulate the activity of LSdSst neurons under stressful circumstances.

Delta-9 tetrahydrocannabinol (THC) effects on the cortisol stress response in bovine granulosa cells

Maternal stress can result in changes in the hypothalamic-pituitary-adrenal (HPA) axis and lead to stress-related behaviours in offspring. Under physiological conditions, delta-9 tetrahydrocannabinol (THC) appears to be detrimental for fertility. However, cannabis is also commonly used for stress-relief. THC acts on the endocannabinoid receptors in granulosa cells (GCs), which affect oocyte competency. The objective of this study was to evaluate the effects of THC on in vitro bovine granulosa cell viability, apoptosis, and stress response pathway. GCs were cultured in vitro in the presence of clinically relevant therapeutic and recreational plasma doses of THC. Cortisol doses reflecting normal and elevated plasma levels were used to evaluate the effects of THC under induced stress in vitro. No effect of THC was observed on cell viability or apoptosis. High and low cortisol concentrations caused significant increases in 11β-HSD1 mRNA expression (n = 6, p < 0.0001). Interestingly, when combined with high [THC], there was a significant decrease in 11β-HSD1 expression compared to high and low cortisol treatments alone (p < 0.001, p < 0.05). GR expression was unaffected by cortisol treatments, and low [THC] treatment maintained increased expression in the presence of high and low cortisol treatments (n = 6, p < 0.01, p < 0.0001). Our findings represent a foundation to obtain useful data for evaluating THC potential therapeutic benefit.

Human-animal interactions during on-farm truck loading of finishing pigs for slaughter transport

Finishing pigs and transport drivers (TDs) interact closely when pigs are loaded for transport, which can be very stressful for both. We aimed to investigate relationships between TD handling actions and pig behaviours during loading for slaughter transport. In total 2,476 finishing pigs were loaded by 18 TDs (2 women, 16 men) during 18 loadings at 18 pig farms in Sweden over a 6 month period. Tactile, vocal and visual TD handling actions were recorded and characterized as ‘moderately-strongly negative’, ‘mildly negative’ or ‘positive’. In the pigs, ‘stress related’, ‘flow’, ‘disrupted flow’ and ‘relaxed’ behaviours were recorded in all animals within 2 m in front of the TDs, using continuous video recordings, and summarized in 5-s intervals. Logistic models were constructed to estimate associations between actions and behaviours, including the preceding one or two intervals. The odds of stress related behaviour in the pigs was found to increase 5.4 and 4.1 times when a moderately-strongly negative and any negative TD action, respectively, occurred in the same interval. When a moderately-strongly negative and any negative TD action occurred in the preceding interval, the odds of stress related behaviour increased 2.0 times and 1.4 times, respectively. The odds of disrupted flow increased 1.6 times when any negative TD action occurred in the same interval. Furthermore, the odds of moderately-strongly negative TD action increased 5.4, 3.4 and 1.9 times, and the odds of any negative TD action increased 3.6, 2.9 and 2.1 times when stress related pig behaviour occurred in the same interval, the preceding interval and the interval before that, respectively. Positive TD action in the same or preceding interval was associated with relaxed pig behaviour. This study suggests a reciprocal relationship between TD actions and pig behaviour, which provides an opportunity to improve TD actions through training in order to reduce stress behaviours in pigs.

The Role of Gut Dysbiosis in the Pathophysiology of Neuropsychiatric Disorders

Mounting evidence shows that the complex gut microbial ecosystem in the human gastrointestinal (GI) tract regulates the physiology of the central nervous system (CNS) via microbiota and the gut-brain (MGB) axis. The GI microbial ecosystem communicates with the brain through the neuroendocrine, immune, and autonomic nervous systems. Recent studies have bolstered the involvement of dysfunctional MGB axis signaling in the pathophysiology of several neurodegenerative, neurodevelopmental, and neuropsychiatric disorders (NPDs). Several investigations on the dynamic microbial system and genetic-environmental interactions with the gut microbiota (GM) have shown that changes in the composition, diversity and/or functions of gut microbes (termed "gut dysbiosis" (GD)) affect neuropsychiatric health by inducing alterations in the signaling pathways of the MGB axis. Interestingly, both preclinical and clinical evidence shows a positive correlation between GD and the pathogenesis and progression of NPDs. Long-term GD leads to overstimulation of hypothalamic-pituitary-adrenal (HPA) axis and the neuroimmune system, along with altered neurotransmitter levels, resulting in dysfunctional signal transduction, inflammation, increased oxidative stress (OS), mitochondrial dysfunction, and neuronal death. Further studies on the MGB axis have highlighted the significance of GM in the development of brain regions specific to stress-related behaviors, including depression and anxiety, and the immune system in the early life. GD-mediated deregulation of the MGB axis imbalances host homeostasis significantly by disrupting the integrity of the intestinal and blood-brain barrier (BBB), mucus secretion, and gut immune and brain immune functions. This review collates evidence on the potential interaction between GD and NPDs from preclinical and clinical data. Additionally, we summarize the use of non-therapeutic modulators such as pro-, pre-, syn- and post-biotics, and specific diets or fecal microbiota transplantation (FMT), which are promising targets for the management of NPDs.

Lactobacillus delbrueckii reduces anxiety-like behavior in zebrafish through a gut microbiome – brain crosstalk

Certain bacteria possess the ability to reduce anxiety- and stress-related behaviors through the gut microbiome-brain axis. Such bacteria are called psychobiotics, and can be used to improve mood and cognition. However, only a few bacteria have been characterized as psychobiotics, and their exact mechanism of action remains unclear. Hence, in this study we analyzed three different species under the Lactobacillacea family, namely, Lactobacillus delbrueckii, Lacticaseibacillus casei, and Lacticaseibacillus paracasei for their potential psychobiotic activities. L. delbrueckii treatment reduced anxiety-like behavior and increased brain and gut glutamic acid decarboxylase (gad) gene expression in zebrafish. It also altered zebrafish gut microbial community as determined by PCR-DGGE and 16S rRNA-based metagenomics analysis. Overall, this paper showed that L. delbrueckii but not L. paracasei and L. casei, induced a consistent improvement in anxiety-like behavior in zebrafish, implicating its potential role as a psychobiotic to reduce anxiety.This article is part of the Special Issue on 'Microbiome & the Brain: Mechanisms & Maladies'.

FAAH Inhibition Restores Early Life Stress-Induced Alterations in PFC microRNAs Associated with Depressive-Like Behavior in Male and Female Rats.

Early life stress (ELS) increases predisposition to depression. We compared the effects of treatment with the fatty acid amide hydrolase (FAAH) inhibitor URB597, and the selective serotonin reuptake inhibitor paroxetine, on ELS-induced depressive-like behavior and the expression of microRNAs (miRs) associated with depression in the medial prefrontal cortex (mPFC), hippocampal CA1 area, lateral habenula and dorsal raphe in rats. We also examined the mRNA expression of serotonergic (htr1a and slc6a4) and endocannabinoid (cnr1, cnr2 and faah) targets in the mPFC following ELS and pharmacological treatment. Adult males and females exposed to the 'Limited Bedding and Nesting' ELS paradigm demonstrated a depressive-like phenotype and late-adolescence URB597 treatment, but not paroxetine, reversed this phenotype. In the mPFC, ELS downregulated miR-16 in males and miR-135a in females and URB597 treatment restored this effect. In ELS females, the increase in cnr2 and decrease in faah mRNAs in the mPFC were reversed by URB597 treatment. We show for the first time that URB597 reversed ELS-induced mPFC downregulation in specific miRs and stress-related behaviors, suggesting a novel mechanism for the beneficial effects of FAAH inhibition. The differential effects of ELS and URB597 on males and females highlight the importance of developing sex-specific treatment approaches.

Exploiting animal personality to reduce chronic stress in captive fish populations.

Chronic stress is a major source of welfare problems in many captive populations, including fishes. While we have long known that chronic stress effects arise from maladaptive expression of acute stress response pathways, predicting where and when problems will arise is difficult. Here we highlight how insights from animal personality research could be useful in this regard. Since behavior is the first line of organismal defense when challenged by a stressor, assays of shy-bold type personality variation can provide information about individual stress response that is expected to predict susceptibility to chronic stress. Moreover, recent demonstrations that among-individual differences in stress-related physiology and behaviors are underpinned by genetic factors means that selection on behavioral biomarkers could offer a route to genetic improvement of welfare outcomes in captive fish stocks. Here we review the evidence in support of this proposition, identify remaining empirical gaps in our understanding, and set out appropriate criteria to guide development of biomarkers. The article is largely prospective: fundamental research into fish personality shows how behavioral biomarkers could be used to achieve welfare gains in captive fish populations. However, translating potential to actual gains will require an interdisciplinary approach that integrates the expertise and viewpoints of researchers working across animal behavior, genetics, and welfare science.

Preliminary study on the behavioral response of zebrafish to the presence of methionine and polypropylene residues in water

When it comes to pollutants in the aquatic environment, there is a wide variety of products, from fibers and plastics to food and medicinal compounds and their by-products. Pollutants have been an area of interest for decades and are becoming more popular with each passing year, whether their presence and effects are studied separately by class or in combination. Among all, polymeric materials are in the center of attention, and their presence in the environment has long been established with studies on their harmful effects. Improper disposal of pharmaceutical materials is just one of many ways that lead to their accumulation in water and soil. The worldwide spread in the environment of polymeric materials, as well as pharmaceutical pollutants is described by the literature, but also the effects of these two materials separately in terms of the behavior of zebrafish (Danio rerio). In this paper, we studied the "joint effect" of one polymeric material (polypropylene) and one pharmaceutical product (methionine - one of the essential aminoacids of the body, with antioxidant properties and multiple uses in the pharmaceutical field). Although we did not find many significant differences in terms of behavior, one aspect worth noting was the anxiolytic-like effect of microplastic on the social, and stress related behavior of zebrafish.

Intestinal gluconeogenesis: metabolic benefits make sense in the light of evolution.

The intestine, like the liver and kidney, in various vertebrates and humans is able to carry out gluconeogenesis and release glucose into the blood. In the fed post-absorptive state, intestinal glucose is sensed by the gastrointestinal nervous system. The latter initiates a signal to the brain regions controlling energy homeostasis and stress-related behaviour. Intestinal gluconeogenesis (IGN) is activated by several complementary mechanisms, in particular nutritional situations (forexample, when food is enriched in protein or fermentable fibre and after gastric bypass surgery in obesity). In these situations, IGN has several metabolic and behavioural benefits. As IGN is activated by nutrients capable of fuelling systemic gluconeogenesis, IGN could be a signal to the brain that food previously ingested is suitable for maintaining plasma glucose for a while. This process might account for the benefits observed. Finally, in this Perspective, we discuss how the benefits of IGN in fasting and fed states could explain why IGN emerged and was maintained in vertebrates by natural selection.

Potential Utility of Cannabidiol in Stress-Related Disorders.

Background: The endocannabinoid (eCB) system plays an important role in homeostatic regulation of anxiety and stress responses; however, the eCB system can be disrupted following traumatic stressors. Additionally, traumatic or chronic stressors that occur during adulthood or early life can cause long-lasting disturbances in the eCB system. These alterations interfere with hypothalamic-pituitary-adrenal axis function and may be involved in lifelong increased fear and anxiety behaviors as well as increased risk for development of post-traumatic stress disorder (PTSD). Methods: This review focuses on the implications of trauma and significant stressors on eCB functionality and neural pathways, both in adolescence and into adulthood, as well as the current state of testing for CBD efficacy in treating pediatric and adult patients suffering from stress-induced eCB dysregulation. Articles were searched via Pubmed and included studies examining eCB modulation of stress-related disorders in both clinical settings and preclinical models. Conclusion: Given the potential for lifelong alterations in eCB signaling that can mediate stress responsiveness, consideration of pharmaceutical or nutraceutical agents that impact eCB targets may improve clinical outcomes in stress-related disorders. However, caution may be warranted in utilization of medicinal cannabinoid products that contain delta-9-tetrahydrocannabinol due to pronounced euphorigenic effects and potential to exacerbate stress-related behaviors. Other cannabinoid products, such as cannabidiol (CBD), have shown promise in reducing stress-related behaviors in pre-clinical models. Overall, pre-clinical evidence supports CBD as a potential treatment for stress or anxiety disorders resulting from previously stressful events, particularly by reducing fearful behavior and promoting extinction of contextual fear memories, which are hallmarks of PTSD. However, very limited clinical research has been conducted examining the potential effectiveness of CBD in this regard and should be examined further.

The effects of visitors and social isolation from a peer on the behavior of a mixed-species pair of captive gibbons

Human visitors affect the behavior of captive animals, which is the so-called visitor effect. The number and behavior of visitors may influence stress-related behaviors in captive animals, such as self-scratching, yawning, and visitor-directed vigilance. A social group setting can be applied to alleviate such negative visitor effects and facilitate social behavior and interactions between individuals. In this study, we examined how the number and behavior of visitors are related to stress-related behaviors of a captive mixed-species gibbon pair comprising a yellow-cheek gibbon (Nomascus gabriellae) and a white-handed gibbon (Hylobates lar). The two gibbons were separated during the study period, and we examined whether the social isolation stimulated the visitor effect. The frequency of stress-related behaviors of the gibbons increased and the social playing between them decreased proportionally to visitor number. In the indoor enclosure, the gibbons increased their visitor-directed vigilance when visitors shouted or struck the glass partition. Our findings indicate that the number and behavior of visitors negatively affect captive gibbons and that a mixed-species social setting can help gibbons reduce visitor-induced stress. Future studies with larger sample sizes will improve the understanding of the visitor effect and the social setting in the captivity.

The Significant Role of the Sympathetic Nervous System in Hospitalization and Death of Patients With COVID-19: Psycho-Neuroendocrine-Immune Aspect of Stress

The primary immune responses to CoV-19 are inter-individual variability against this virus. Studies on the neuro-immune system demonstrate that interactions in these communication pathways can be a reason for several psychiatric disorders and immune-mediated diseases. Stress-related behaviors are significant in the psycho-immune interactions, and even stress-related factors such as socioeconomic status can also play a vital role in these interactions. A literature review on the topic was carried out, and 150 articles were included. Catecholamine and glucocorticoids are stress neurohormones. Noradrenaline as signaling molecules, through macrophages, can be an essential stimulus for cytokine secretion. Glucocorticoids, by both pro-and anti-inflammatory roles in specific conditions, can inhibit the elevation of the inflammatory response by inhibiting the pro-inflammatory macrophage activation and also enhance the anti-inflammatory activity in monocyte/macrophage populations the further eliminate. Stress with this flawed amplification feedback system can disrupt immune homeostasis (cytokine storm) in the patient with COVID-19. This investigation showed that there is a strong link between psycho-neuroendocrine-immune axis organizations against respiratory viral infections during the COVID-19 epidemic. The stress cascade must be responsible for meeting the body's hemostatic challenges in the necessary physiological and metabolic interactions. The motivation of the stress system leads to behavioral/physical variations that are strangely consistent in their qualitative presentation. These variations must be generally adaptive and increase the chances of the individual's survival. In coronavirus respiratory disease, identifying people with acute/chronic psychosocial stress is of particular importance for providing prompt care as soon as possible, as scheduling intervention appears to be an essential factor in reducing stress and hospitalization rate in the intensive care unit (ICU).