Physiological adaptations to chronic stress in healthy humans - why might the sexes have evolved different energy utilisation strategies?

A comparative study of stress experienced by Swedish and Norwegian police officers

Introduction

Police officers work in a variable environment under different circumstances and often involves stressful situations. This include working irregular hours, ongoing exposure to critical incidents, confrontations and violence. community police officers are mainly out in the society and have daily contact with the general public. critical incidents can also consist of being criticized and stigmatized as a police officer, both from the public but also lack of support from their own organization. There is evidence on negative impacts of stress on police officers. However, knowledge about the nature of police stress and its various types is insufficient. It is assumed that there are common stress factors which are universal among all police officers in different contexts but there is a lack of comparative studies to provide empirical evidence. The aim of this study is to compare different types of stress among police officers in Norway and Sweden and how the pattern of experiencing stress has changed over time in these countries.

Methods

The study population consisted of patrolling police officers from 20 local police districts or units in all seven regions in Sweden (n = 953) and patrolling police officers from four police districts in Norway (n = 678). A 42-item Police Stress Identification Questionnaire was used to measure the stress level.

Results

The findings show differences in types of stressful events as well as its severity among police officers in Sweden and Norway. The level of stress decreased over time among Swedish police officers whereas it showed no change or even an increase among the Norwegian participants.

Discussion

The results of this study are relevant for policy-makers, police authorities and lay police officers in each country to tailor their efforts to prevent stress among police officers.

A Longitudinal Study of Life Trauma, Chronic Stress and Body Mass Index on Weight Gain over a 2-Year Period

The United States is facing an alarming and increasing obesity epidemic. Stress is associated with obesity, but specific longitudinal effects of life trauma on weight gain have not been assessed. Here we examined if life trauma and chronic stress predicted weight gain while also measuring the impact of body mass index (BMI). Life trauma and chronic stress were assessed with the Cumulative Adversity Interview (CAI). Weight and BMI were captured repeatedly over a two-year period. Results show significant increases in weight gain over time. Individuals with obesity (IOb) reported significantly higher levels of life trauma at the onset compared to overweight (IOw) and lean individuals (Il). Greater numbers of trauma events were associated with increased weight gain for both IOb and IOw but not for Il. Increased chronic stress was not consistently associated with weight gain over time. Current findings suggest the need to address trauma coping, especially in vulnerable individuals to prevent greater weight gain and curb obesity-related health outcomes.

Innervated adrenomedullary microphysiological system to model nicotine and opioid exposure

Transition to extrauterine life results in a surge of catecholamines necessary for increased cardiovascular, respiratory, and metabolic activity. Mechanisms mediating adrenomedullary catecholamine release are poorly understood. Important mechanistic insight is provided by newborns delivered by cesarean section or subjected to prenatal nicotine or opioid exposure, demonstrating impaired release of adrenomedullary catecholamines. To investigate mechanisms regulating adrenomedullary innervation, we developed compartmentalized 3D microphysiological systems (MPS) by exploiting GelPins, capillary pressure barriers between cell-laden hydrogels. The MPS comprises discrete cultures of adrenal chromaffin cells and preganglionic sympathetic neurons within a contiguous bioengineered microtissue. Using this model, we demonstrate that adrenal chromaffin innervation plays a critical role in hypoxia-mediated catecholamine release. Opioids and nicotine were shown to affect adrenal chromaffin cell response to a reduced oxygen environment, but neurogenic control mechanisms remained intact. GelPin containing MPS represent an inexpensive and highly adaptable approach to study innervated organ systems and improve drug screening platforms.

Pyruvate accumulation may contribute to acceleration-induced impairment of physical and cognitive abilities: an experimental study

Background: Fatigue can be induced after acceleration exposure, however its mechanism is still unclear. The aim of the present study was to examine whether metabolites’ changes can decrease cognitive and physical function after acceleration. Methods: Graybiel scale and Fatigue Self-rating scale were used to assess the seasickness and fatigue degrees of 87 male seafarers respectively after sailing. To test the effect of pyruvate on cognitive and physical functions, five different doses of pyruvate were administrated into rats. Insulin can reduce the accumulation of pyruvate. To observe the insulin effect on pyruvate, cognitive and physical functions after acceleration, insulin administration or treatment of promoting insulin secretion was used. Physical and cognitive functions were assessed using open field test (OFT), morris water maze (MWM) and loaded swimming test (LST) in animals. Results: Physical and cognitive abilities were decreased obviously, and serum pyruvate increased mostly in human and rats after acceleration. Compared with vehicle group, physical and cognitive abilities were significantly decreased after pyruvate administration. Besides, we found a significant decline in adenosine triphosphate (ATP) concentration and pyruvate dehydrogenase (PDH) activity in the hippocampus, prefrontal cortex, liver, and muscle of rats treated with acceleration or pyruvate injection, while insulin administration or treatment of promoting insulin secretion markedly alleviated this decline and the impairment of physical and cognitive abilities, compared with the control group. Conclusion: Our results indicate that pyruvate has a negative effect on physical and cognitive abilities after acceleration. Insulin can inhibit pyruvate accumulation and cognitive and physical function after acceleration exposure.

A Longitudinal Epigenetic Aging and Leukocyte Analysis of Simulated Space Travel: The Mars-500 Mission

Astronauts undertaking long-duration space missions may be vulnerable to unique stressors that can impact human aging. Nevertheless, few studies have examined the relationship of mission duration with DNA-methylation-based biomarkers of aging in astronauts. Using data from the six participants of the Mars-500 mission, a high-fidelity 520-day ground simulation experiment, we tested relationships of mission duration with five longitudinally measured blood DNA-methylation-based metrics: DNAmGrimAge, DNAmPhenoAge, DNA-methylation-based estimator of telomere length (DNAmTL), mitotic divisions (epigenetic mitotic clock [epiTOC2]), and pace of aging (PoA). We provide evidence that, relative to baseline, mission duration was associated with significant decreases in epigenetic aging. However, only decreases in DNAmPhenoAge remained significant 7 days post-mission. We also observed significant changes in estimated proportions of plasmablasts, CD4T, CD8 naive, and natural killer (NK) cells. Only decreases in NK cells remained significant post-mission. If confirmed more broadly, these findings contribute insights to improve the understanding of the biological aging implications for individuals experiencing long-duration space travel.

Long-duration space travel is marked by a unique combination of stressors known to impact human aging. Using data from six participants of the Mars-500 mission, a high-fidelity 520-day ground simulation experiment, Nwanaji-Enwerem et al. report significant associations of mission duration with decreased biological aging measured via blood DNA methylation.

Relationship Between Chronic Stress and Heart Rate Over Time Modulated by Gender in a Cohort of Office Workers: Cross-Sectional Study Using Wearable Technologies

Background

Chronic stress is increasing in prevalence and is associated with several physical and mental disorders. Although it is proven that acute stress changes physiology, much less is known about the relationship between physiology and long-term stress. Continuous measurement of vital signs in daily life and chronic stress detection algorithms could serve this purpose. For this, it is paramount to model the effects of chronic stress on human physiology and include other cofounders, such as demographics, enabling the enrichment of a population-wide approach with individual variations.

Objective

The main objectives of this study were to investigate the effect of chronic stress on heart rate (HR) over time while correcting for weekdays versus weekends and to test a possible modulation effect by gender and age in a healthy cohort.

Methods

Throughout 2016 and 2017, healthy employees of technology companies were asked to participate in a 5-day observation stress study. They were required to wear two wearables, of which one included an electrocardiogram sensor. The derived HR was averaged per hour and served as an output for a mixed design model including a trigonometric fit over time with four harmonics (periods of 24, 12, 8, and 6 hours), gender, age, whether it was a workday or weekend day, and a chronic stress score derived from the Perceived Stress Scale (PSS) as predictors.

Results

The study included 328 subjects, of which 142 were female and 186 were male participants, with a mean age of 38.9 (SD 10.2) years and a mean PSS score of 13.7 (SD 6.0). As main effects, gender (χ²₁=24.02, P<.001); the hour of the day (χ²₁=73.22, P<.001); the circadian harmonic (χ²₂=284.4, P<.001); and the harmonic over 12 hours (χ²₂=242.1, P<.001), over 8 hours (χ²₂=23.78, P<.001), and over 6 hours (χ²₂=82.96, P<.001) had a significant effect on HR. Two three-way interaction effects were found. The interaction of age, whether it was a workday or weekend day, and the circadian harmonic over time were significantly correlated with HR (χ²₂=7.13, P=.03), as well as the interaction of gender, PSS score, and the circadian harmonic over time (χ²₂=7.59, P=.02).

Conclusions

The results show a relationship between HR and the three-way interaction of chronic stress, gender, and the circadian harmonic. The modulation by gender might be related to evolution-based energy utilization strategies, as suggested in related literature studies. More research, including daily cortisol assessment, longer recordings, and a wider population, should be performed to confirm this interpretation. This would enable the development of more complete and personalized models of chronic stress.

Effort-reward imbalance at work and weight changes in a nationwide cohort of workers in Denmark

Objective

To investigate the relation between effort‐reward imbalance (ERI) at work and subsequent weight changes.

Methods

We included participants from a population‐based cohort of workers in Denmark (mean age = 47 years, 54% women) with two (n = 9005) or three repeated measurements (n = 5710). We investigated the association between (a) ERI (ie, the mismatch between high efforts spent and low rewards received at work) at baseline and weight changes after a 2‐year follow‐up (defined as ≥5% increase or decrease in body mass index (BMI) vs stable), and (b) onset and remission of ERI and subsequent changes in BMI. Using multinomial logistic regression we calculated risk ratios (RR) and 95% confidence intervals (CI), adjusted for sex, age, education, cohabitation, migration background, and follow‐up time.

Results

After 2 years, 15% had an increase and 13% a decrease in BMI. Exposure to ERI at baseline yielded RRs of 1.09 (95% CI: 0.95‐1.25) and 1.04 (95% CI: 0.90‐1.20) for the increase and decrease in BMI, respectively. There were no differences between sex and baseline BMI in stratified analyses. The onset of ERI yielded RRs of 1.04 (95% CI: 0.82‐1.31) and 1.15 (95% CI: 0.84‐1.57) for subsequent increase and decrease in BMI. The RRs for the remission of ERI and subsequent increase and decrease in BMI were 0.92 (95% CI: 0.71‐1.20) and 0.78 (95% CI: 0.53‐1.13), respectively. Of the ERI components, high rewards were associated with a lower risk of BMI increase.

Conclusion

ERI was not a risk factor for weight changes. Future studies may investigate whether this result is generalizable to other occupational cohorts and settings.

Therapeutic Potential of Brassinosteroids in Biomedical and Clinical Research

Steroids are a pivotal class of hormones with a key role in growth modulation and signal transduction in multicellular organisms. Synthetic steroids are widely used to cure large array of viral, fungal, bacterial, and cancerous infections. Brassinosteroids (BRs) are a natural collection of phytosterols, which have structural similarity with animal steroids. BRs are dispersed universally throughout the plant kingdom. These plant steroids are well known to modulate a plethora of physiological responses in plants leading to improvement in quality as well as yield of food crops. Moreover, they have been found to play imperative role in stress-fortification against various stresses in plants. Over a decade, BRs have conquered worldwide interest due to their diverse biological activities in animal systems. Recent studies have indicated anticancerous, antiangiogenic, antiviral, antigenotoxic, antifungal, and antibacterial bioactivities of BRs in the animal test systems. BRs inhibit replication of viruses and induce cytotoxic effects on cancerous cell lines. Keeping in view the biological activities of BRs, this review is an attempt to update the information about prospects of BRs in biomedical and clinical application.

Chronic stress, physiological adaptation and developmental programming of the neuroendocrine stress system

Chronic stress undermines physical and mental health, in part via dysregulation of the neuroendocrine stress system. Key to understand this dysregulation is recognizing that the problem is not stress per se, but rather its chronicity. The optimally functioning stress system is highly dynamic, and negative feedback regulation enforces transient responses to acute stressors. Chronic stress overrides this, and adaptation to the chronicity can result in persistent dysregulation by altering sensitivity thresholds critical for control of system dynamics. Such adaptation involves plasticity within the central nervous system (CNS) as well as epigenetic regulation. When it occurs during development, it can have persistent effects on neuroendocrine regulation. Understanding how chronic stress programs development of the neuroendocrine stress system requires elucidation of stress-responsive gene regulatory networks that control CNS plasticity and development.

Impact of chronic unpredicted mild stress-induced depression on repaglinide fate via glucocorticoid signaling pathway

Chronic unpredicted mild stress (CUMS)-induced depression could alter the pharmacokinetics of many drugs in rats, however, the underlying mechanism is not clear. In this work we studied the pharmacokinetics of repaglinide, and explored the role of glucocorticoid and adrenergic signaling pathway in regulating drug metabolizing enzymes (DMEs) in GK rats and BRL 3A cells. The plasma cortisol and epinephrine levels were increased, meanwhile the pharmacokinetics of repaglinide were altered significantly in depression model rats. Forty-nine genes in liver of model rats displayed significant difference comparing to control rats. The differentially expressed genes enriched in the drug metabolism and steroid hormone biosynthesis pathway significantly, and Nr1i3 matched 335 connectivity genes. CAR and Ugt1a1 protein expression were enhanced significantly in liver of model rats. The mRNA expression of Ugt1a1 and Nr1i2 were increased 2 and 4 times respectively with dexamethasone (DEX) and 8-Br-cAMP co-treatment in BRL 3A cells. The protein expression of PXR was up-regulated, too. However, RU486 reversed the up-regulated effect. The adrenergic receptor agonists had little impact on the DMEs in BRL 3A. Our data suggested that CUMS-induced depression might up-regulate DMEs expression via glucocorticoid signaling pathway, and accelerate the fate of the repaglinide in spontaneous diabetes rats.