Sympathetic-adrenal Medullary System Research Articles

It's cool to be stressed: Body surface temperatures track sympathetic nervous system activation during acute stress.

The acute stress response can be considered the primary evolutionary adaptation to maximise fitness in the face of unpredictable environmental challenges. However, the difficulties of assessing physiology in natural environments mean comparatively little is known about how response variation influences fitness in free-living animals. Currently, determining acute stress physiology typically involves blood sampling or cardiac monitoring. Both require trapping and handling, interrupting natural behaviour, and potentially biasing our understanding toward trappable species/individuals. Importantly, limits on repeated sampling also restrict response phenotype characterisation, vital for linking stress with fitness. Surface temperature dynamics resulting from peripheral vasomotor activity during acute stress are increasingly promoted as alternative physiological stress indicators, which can be measured non-invasively using infrared thermal imaging, overcoming many limitations of current methods. Nonetheless, which aspects of stress physiology they represent remains unclear, as the underlying mechanisms are unknown. To date, validations have primarily targeted the hypothalamic-pituitary-adrenal axis, when the sympathetic-adrenal-medullary (SAM) system is likely the primary driver of vasomotor activity during acute stress. To address this deficit, we compared eye and bill region surface temperatures - measured using thermal imaging - with SAM system activity - measured as heart-rate-variability via electrocardiogram telemetry - in wild-caught captive house sparrows (Passer domesticus), during capture and handling. We found lower body surface temperatures were associated with increased sympathetic nervous system activation. Consequently, our data confirm body surface temperatures can act as a proxy for sympathetic activation during acute stress, providing potentially transformative opportunities for linking the acute stress response with fitness in the wild.

Abstract 11105: Real Time Racial Microaggression and Physiological Stress Responses Among Young and Middle Aged Black Adults

Introduction: Perceived racial discrimination has been associated with dysregulation of sympathetic-adrenal-medullary (SAM) and hypothalamic-pituitary-adrenal (HPA) axis, two major physiological stress response systems linked to cardiovascular disease outcomes. Most studies, to date, used cross-sectional data that captured retrospective measures of lifetime racial discrimination associated with current physiological stress responses. Relative to overt racial discrimination, a subtle form of racial discrimination, known as microaggression is more prevalent, yet most commonly measured retrospectively, and understudied. The purpose of this pilot study was to examine the relationship between microaggression measured in real-time and physiological stress responses. Methods: Twelve healthy Black adults (mean age=43.4 years) completed baseline surveys, and self-collected saliva 4x a day for 4 days to measure cortisol and alpha amylase (AA) as a proxy of HPA and SAM systems, respectively. Real-time microaggression was measured using ecological momentary assessments (EMA) sent to participants 5x a day for 7 days. Multilevel models were conducted to examine the relationship between microaggressions and the SAM and HPA axis activities. Results: In the bivariate analyses, the area under the curve with respect to ground (AUCg: total cortisol output throughout the day) was significantly associated with the same day microaggression (r=.40, p=.02). Microaggression was associated with cortisol awakening response (CAR) on the same day (r=.34, p=.04). In multilevel models, microaggression was associated with wake-up cortisol level on the same day (β=.22, p=.05). Microaggression was also associated with wake-up AA levels both the same day (β=.58, p<.01) and the next day (β=.40, p=.05). Conclusions: Microaggression was associated with same day and next day physiological stress responses. We determined that concurrent use of salivary biomarkers and EMA was feasible methods to examine the temporal relationship between microaggression and physiological stress responses. Future work will include the development of an intervention that buffers the physiologic stress response related to microaggression to improve cardiovascular health.

Effect of Infection With Scabies on The Adrenaline Hormone Of Patients With Chronic Diseases In Basra City/ Southern Iraq

Scabies, a parasitic skin infestation by the burrowing “itch” mite Sarcoptes scabiei, causes significant health problems for children and adults worldwide. Crusted scabies is a particularly severe form of scabies in which mites multiply into the millions, causing extensive skin crusting. The symptoms and signs of scabies suggest host immunity to the scabies mite. The defense against stress is executed by the hypothalamic-pituitary-adrenal axis and the sympathetic-adrenal medullary system. Adrenal gland is a major effector organ of stress system. During stress, adrenal gland rapidly responds with increased secretion of glucocorticoids (GCs) and catecholamines into circulation, which hormones, in turn, affect metabolism, to provide acutely energy, vasculature to increase blood pressure, and the immune system to prevent it from extensive activation. . The current study examined (80) people, of whom (16) had negative control samples and (64) had scabies and had chronic diseases such as heart disease, diabetes, pressure, lung, liver, kidneys, ulcers, cancer, anemia and epilepsy, the current study recorded the highest levels of adrenaline using the associated immunosorbent assay technique With the enzyme (ELISA), which is (523 pg / ml) for patients suffering from chronic heart disease and infected with the scabies mite parasite and their number (14) out of (64) have other chronic diseases and their percentage was (21.88%) and the current study recorded the lowest levels of the hormone adrenaline. In patients with scabies and suffering from epilepsy at a rate (219 pg / ml) percentage (1.56%), which shows the hormone levels in patients with scabies and suffering from chronic diseases and comparing them with the control samples .

Daily Stressors and Physiological Reactivity: The Role of Perceived Stress, Stress Reactivity, Neuroticism, and Age

Exposure to stressful events is an inevitable aspect of everyday life, such as encountering work deadlines or interpersonal conflicts. The body’s physiological stress systems can become activated when exposed to stressors, resulting in increases in cortisol from the hypothalamic-pituitary-adrenal axis and/or increases in the alpha-amylase enzyme via the sympathetic-adrenal medullary system. We predicted physiological reactivity measured by salivary assay in an ecological momentary assessment (EMA) design, using The Perceived Stress Scale (PSS; Cohen, 1988), Perceived Stress Reactivity Scale (PSRS; Schulz, Jansen, & Schlotz, 2005), neuroticism, (Big Five Inventory; John, Donahue, & Kentle, 1991), and age. Adult participants (N=163) ages 20–80 years old (M=51.8 years) completed the individual differences measures and then provided seven saliva samples per day for 10 consecutive days while also completing five stress-related surveys per day via random-prompted EMA (Scott, Sliwinski, & Blanchard-Fields, 2013). Mean aggregate alpha-amylase correlated with the PSRS (r = -.20, p < .05) but not with the PSS or with neuroticism, suggesting alpha-amylase may be a more sensitive measure of subjective stress reactivity. In contrast, mean cortisol levels were not correlated with any of those measures. Age correlated with subjective stress (r = -.23, p < .05) and stress reactivity (r = -.20, p < .05) but not with hormone levels. Multilevel modeling will be used to evaluate within-person and between-person variation in stress hormones and EMA measures of daily stress in relation to the PSS, the PSRS, neuroticism, and age.

Pilot Study of the Relationship between Deck Level and Journey Duration on Plasma Cortisol, Epinephrine and Norepinephrine Levels in Italian Heavy Pigs.

Simple SummaryJourney duration, position of the animal in the vehicle and time spent in the lairage facilities before slaughtering can negatively affect pig welfare. The effects of journey duration and deck level on hormonal parameters were examined in this pilot study during three commercial truckloads. Plasma cortisol, epinephrine and norepinephrine increased with longer transportation time. The levels of the tested hormones were higher in pigs transported for 11 h than for 6.5 h or only 3 h. The loading position (deck level) of the animals on the truck strongly affected only norepinephrine. While the effects of journey duration on plasma cortisol levels were expected and in line with the literature, our findings on plasma catecholamines are novel and may be useful to monitor transportation stress responses in pigs. These preliminary findings need to be confirmed by future studies.The aim of this pilot study was to evaluate the relationship between journey duration, deck level and activation patterns of the hypothalamic-pituitary-adrenocortical axis (HPA) and sympathetic adrenal medullary system (SAM) in pigs. A total of 90 pigs were examined. The animals came from three different Italian farms associated with the same slaughterhouse located in Bari (Apulia region-Italy). A group of thirty animals was transported from Pordenone (11 h journey); a second group was transported from Terni (6.5 h journey); a third group was transported from Benevento (3 h journey). The animals were transported in the same vehicle, which complied with the structural characteristics indicated in the Council Regulation (EC) No. 1/2005. The truck was composed of a lorry and a trailer, each one divided into three decks. Only the animals transported in the trailer were tested for the study. Before transportation, blood samples were collected on each farm, at 6:00 a.m., from 30 pigs randomly selected out of 135 pigs ready to be transported. Blood samples were also collected during slaughter to evaluate plasma cortisol, epinephrine and norepinephrine, around 6:00 a.m. A journey duration of 11 h was associated with significantly higher plasma concentrations of stress hormones compared with shorter journeys. This increase was proportional to the journey duration, with the pigs travelling for 6.5 h displaying intermediate concentrations between those noticed after 3 h and 11 h journeys. The interaction between deck and journey distance was not significant on epinephrine, norepinephrine or cortisol levels collected at arrival. There was a significant effect of deck level on norepinephrine levels (p < 0.0001), a tendency to influence epinephrine levels (p = 0.073) but no effect on cortisol levels (p = 0.945). Overall, we observed that an 11 h-long journey seemed to impact negatively on pigs’ HPA-SAM activity, likely requiring the animals to spend more time in the lairage facilities to recover.

Quantifying the Autonomic Response to Stressors-One Way to Expand the Definition of "Stress" in Animals.

Quantifying how whole organisms respond to challenges in the external and internal environment ("stressors") is difficult. To date, physiological ecologists have mostly used measures of glucocorticoids (GCs) to assess the impact of stressors on animals. This is of course too simplistic as Hans Seyle himself characterized the response of organisms to "noxious stimuli" using multiple physiological responses. Possible solutions include increasing the number of biomarkers to more accurately characterize the "stress state" of animal or just measuring different biomarkers to more accurately characterize the degree of acute or chronic stressors an animal is experiencing. We focus on the latter and discuss how heart rate (HR) and heart rate variability (HRV) may be better predictors of the degree of activation of the sympathetic-adrenal-medullary system and complement or even replace measures of GCs as indicators of animal health, welfare, fitness, or their level of exposure to stressors. The miniaturization of biological sensor technology ("bio-sensors" or "bio-loggers") presents an opportunity to reassess measures of stress state and develop new approaches. We describe some modern approaches to gathering these HR and HRV data in free-living animals with the aim that heart dynamics will be more integrated with measures of GCs as bio-markers of stress state and predictors of fitness in free-living animals.

The different hormonal system during exercise stress coping in horses.

The review discusses the hormonal changes during exercise stress. The exercise generally produces a rise of adrenaline (A), noradrenaline (NA), adrenocorticotropic hormone (ACTH), cortisol, glucagon, growth hormone, arginine vasopressine, etc., and a drop of insulin. The hormonal events during reestablishment of homeostasis due to exercise stress can be divided into a catabolic phase, with decreased tolerance of effort, and reversible biochemical, hormonal and immunological changes, and an anabolic phase, with a higher adaptive capacity, and enhanced performance. The two main hormonal axes activated in the catabolic phase are sympathetic–adrenal–medullary system and hypothalamic-pituitary-adrenal (HPA) axis, while in the anabolic phase, growth hormone-insulin-like factor I axis, and gonadal axes. The hormonal responses during exercise and recovery can be regarded as regulatory and integrated endocrine responses. The increase of catecholamines and ACTH is dependent on the intensity of exercise; a marked increase in plasma A occurs during exercises with high emotional content. The response of cortisol is correlated with the duration of exercise, while the effect of exercise duration on b-endorphin changes is highly dependent on the type of exercise performed. Cortisol and b-endorphin changes usually occur in phase, but not during exercises with high emotional content. Glucocorticoids and iodothyronines are involved in meeting immediate energy demands, and a model of functional interactions between HPA axis and hypothalamic-pituitary-thyroid axis during exercise stress is proposed. A modulation of coping responses to different energy demanding physical activities required for sport activities could be hypothesized. This review supports the proposed regulation of hypophysiotropic TRHergic neurons as metabolic integrators during exercise stress. Many hormonal systems (ghrelin, leptin, glucose, insulin, and cortisol) are activated to control substrate mobilizations and utilization. The cardiovascular homeostasis, the fluid and electrolyte balance during exercise are highly dependent on vasoactive hormones (antidiuretic hormone, atrial natriuretic peptide, renin–angiotensin–aldosterone, and prostaglandins) control.

Blockade of Stellate Ganglion Remediates Hemorrhagic Shock–Induced Intestinal Barrier Dysfunction

BackgroundAcute hemorrhage-induced excessive excitation of sympathetic–adrenal–medullary system (SAS) leads to gut hypoperfusion and barrier dysfunction, which is a critical event during hemorrhagic shock–induced multiple organ injury. Stellate ganglion blockade (SGB) has been widely used for suppression of sympathetic–adrenal–medullary system in the clinical practice. However, whether SGB improves intestinal barrier function after hemorrhagic shock remains unclear. Here, we hypothesized that the implementation of SGB restores intestinal barrier function and reduces gut injury. Materials and methodsMale rats received the SGB pretreatment and underwent hemorrhagic shock followed by resuscitation. The 96-h survival rate, intestinal permeability and morphology, D-lactic acid concentration and diamine oxidase activity in plasma, and expressions of F-actin, Claudin-1, and E-cadherin in intestinal tissues were observed. ResultsPretreatment with SGB significantly enhances the 96-h survival rate in rats subjected to hemorrhagic shock (from 8.3% to 66.7%). Hemorrhagic shock reduced the coverage scale of intestinal mucus and intestinal villus width and height, enhanced the intestinal permeability to fluorescein isothiocyanate-dextran 4 and D-lactic acid concentration in plasma, and decreased the expressions of F-actin, Claudin-1, and E-Cadherin in intestinal tissue. These hemorrhagic shock–induced adverse effects were abolished by SGB treatment. ConclusionsSGB treatment has a beneficial effect during hemorrhagic shock, which is associated with the improvement of intestine barrier function. SGB may be considered as a new therapeutic strategy for treatment of hemorrhagic shock.

PO-066 The Function of t Lycium Barbarum Juice Supplemen in Exercise Stress Regulation during Increasing Resistance Training

Objective The purpose of this study was to explore the function of Lycium Barbarum juice on exercise stress regulation when male university students drank Lycium Barbarum juice during increasing resistance exercise, by observing the effects of oral Lycium Barbarum juice on the blood glucose, serum Adrenocorticotropic Hormone (ACTH), insulin and glucagon concentration.&#x0D; Methods 21 to 22, healthy, 28 male university students participated in the study. They were randomly divided into a control group (n=16)and an experimental group(n=12). All participants completed four-stage incremental load movement for a total of 32 days. The exercise intensity of four stages was 60% VO2max, 70% VO2max, 80% VO2max and 90% VO2max, respectively. Each stage was exercised every-other-day, 4 times per stage and 1 hour each time. During the exercise, each subject in the experimental group drank 100 ml of 100% Lycium Barbarum juice before going to bed every day.&#x0D; Before the experiment and the morning after the end of each phase, a participant’s elbow-venous blood was collected to separate the serum. In all serum substances, the concentrations of ACTH, insulin, glucagon were detected by ELISA system. Fasting blood glucose concentration was detected by a blood glucose meter (Kyoto GT-1640 glucose meter, Japan). SPSS 17.0 software was used for statistical analysis.&#x0D; Results 1) The serum ACTH concentration of the subjects continually increased with the progress of the incremental load exercise and reached the highest at the end of the fourth stage. Compared with the increase in the control group (P&lt;0.05), the experimental group was more significant (P&lt;0.01). 2) Compared with before the experiment, both control group and experimental group were no obvious changes of blood glucose concentration in the first and second stages, and the control group was significantly decreased in the third and fourth stages (P&lt;0.05), while the experimental group was not (P&gt;0.05). 3) During the increasing load exercise, the changes of insulin in serum of the participants were basically the same. The insulin level increased significantly at the end of the first stage and decreased successively at the end of the last three stages. At the end of the fourth stage, the serum insulin level of the control group decreased more significantly (P&lt;0.05) than the experimental group (P&gt;0.05). 4) The glucagon concentration in the control group continued to increase with the increase of the load. By contrast, the glucagon concentration in the experimental group gradually decreased at the end of the first stage and then increased at the end of the fourth stage. However, all of the increase and decrease are not statistically significant.&#x0D; Conclusions During increasing resistance exercise, drinking Lycium Barbarum juice can increase the ability of the body to regulate Adrenocorticotropic Hormone (ACTH), insulin and glucagon through the exercise stress regulation systems, the Hypothalamic-Pituitary-Adrenal Cortical Hormone system (HPA) and the Sympathetic-Adrenal Medullary system. It plays an important role in maintaining blood sugar levels during increasing resistance exercise and accelerating post-exercise function recovery after exercise.

Daily Social Interactions and the Biological Stress Response: Are There Age Differences in Links Between Social Interactions and Alpha-Amylase?

According to the strength and vulnerability integration (SAVI) model, older people are better able to avoid negative social interactions than younger people, but when they do experience negative interactions, they are equally or more emotionally and physiologically reactive than younger people. Less is known about the links between daily negative and positive social encounters and the sympathetic adrenal medullary system (a key stress pathway) and whether there are age differences in these links. This study considers whether negative and positive social interactions are associated with diurnal alpha-amylase (a measure of the sympathetic adrenal medullary system) and whether there are differences in these links by age. Participants were from the Daily Health, Stress, and Relationship Study, which includes a random sample of 89 individuals (aged 40-95) who completed 14 days of daily diary interviews and provided saliva samples four times a day (wake, 30 min after wake, lunch, and bedtime) for four of those days that were assayed for alpha-amylase. Days in which people reported more negative interactions were associated with flatter morning declines in alpha-amylase, indicating greater stress. Links between positive interactions and diurnal alpha-amylase varied by age group. Findings are consistent with the SAVI model indicating that older adults respond differently to social stimuli than younger people.

Nociceptive Cortical Activity Is Dissociated from Nociceptive Behavior in Newborn Human Infants under Stress

SummaryNewborn infants display strong nociceptive behavior in response to tissue damaging stimuli, and this is accompanied by nociceptive activity generated in subcortical and cortical areas of the brain [1, 2]. In the absence of verbal report, these nociceptive responses are used as measures of pain sensation in newborn humans, as they are in animals [3, 4]. However, many infants are raised in a physiologically stressful environment, and little is known about the effect of background levels of stress upon their pain responses. In adults, acute physiological stress causes hyperalgesia [5, 6, 7], and increased background stress increases pain [8, 9, 10], but these data cannot necessarily be extrapolated to infants. Here we have simultaneously measured nociceptive behavior, brain activity, and levels of physiological stress in a sample of 56 newborn human infants aged 36–42 weeks. Salivary cortisol (hypothalamic pituitary axis), heart rate variability (sympathetic adrenal medullary system), EEG event-related potentials (nociceptive cortical activity), and facial expression (behavior) were acquired in individual infants following a clinically required heel lance. We show that infants with higher levels of stress exhibit larger amplitude cortical nociceptive responses, but this is not reflected in their behavior. Furthermore, while nociceptive behavior and cortical activity are normally correlated, this relationship is disrupted in infants with high levels of physiological stress. Brain activity evoked by noxious stimulation is therefore enhanced by stress, but this cannot be deduced from observation of pain behavior. This may be important in the prevention of adverse effects of early repetitive pain on brain development.

Adrenal Gland Microenvironment and Its Involvement in the Regulation of Stress-Induced Hormone Secretion during Sepsis

Survival of all living organisms depends on maintenance of a steady state of homeostasis, which process relies on its ability to react and adapt to various physical and emotional threats. The defense against stress is executed by the hypothalamic–pituitary–adrenal axis and the sympathetic–adrenal medullary system. Adrenal gland is a major effector organ of stress system. During stress, adrenal gland rapidly responds with increased secretion of glucocorticoids (GCs) and catecholamines into circulation, which hormones, in turn, affect metabolism, to provide acutely energy, vasculature to increase blood pressure, and the immune system to prevent it from extensive activation. Sepsis resulting from microbial infections is a sustained and extreme example of stress situation. In many critical ill patients, levels of both corticotropin-releasing hormone and adrenocorticotropin, the two major regulators of adrenal hormone production, are suppressed. Levels of GCs, however, remain normal or are elevated in these patients, suggesting a shift from central to local intra-adrenal regulation of adrenal stress response. Among many mechanisms potentially involved in this process, reduced GC metabolism and activation of intra-adrenal cellular systems composed of adrenocortical and adrenomedullary cells, endothelial cells, and resident and recruited immune cells play a key role. Hence, dysregulated function of any of these cells and cellular compartments can ultimately affect adrenal stress response. The purpose of this mini review is to highlight recent insights into our understanding of the adrenal gland microenvironment and its role in coordination of stress-induced hormone secretion.

Stress of stoicism: Low emotionality and high control lead to increases in allostatic load

ABSTRACTThe present longitudinal study examined the combined effects of task persistence and negative emotionality (NE) on allostatic load (AL), a physiological indicator of chronic stress. In line with John Henryism theory, we hypothesized that high persistence combined with low NE may be indicative of a high-effort coping style, leading to high arousal of the nervous system and, as a consequence, increased AL. Mothers reported on children’s NE (N = 158, 72 females) at age 9. Persistence was measured at age 9 using a behavioral measure assessing persistence on an impossible task. AL was measured at ages 9 and 17. The AL measure captured hypothalamic pituitary adrenal axis, sympathetic adrenal medullary system, cardiovascular, and metabolic activity. Consistent with previous research, persistence protected against high AL in the context of high NE. However, combined with low NE, high behavioral persistence was associated with higher physiological stress. Our results have implications for both clinical and intervention contexts.

Alcohol Effects on Stress Pathways: Impact on Craving and Relapse Risk.

A significant amount of neurobiological research regarding the development of alcohol use disorders (AUDs) has focused on alcohol-related activation and long-term alterations in the mesocortical dopaminergic reward pathways. However, alcohol does not only interact with brain reward systems. Many of its acute and chronic effects may be related to allostatic adaptations in hypothalamic and extrahypothalamic stress regulation pathways. For example, acute binge intoxication is associated with hypothalamically driven increases in blood cortisol, norepinephrine, and sex steroid metabolite levels. This may contribute to the development of mesocortical sensitization to alcohol. Furthermore, chronic alcohol exposure is associated with systemic dysregulation of the hypothalamic pituitary adrenal axis, sympathetic adrenal medullary system, and sex steroid systems. This dysregulation appears to manifest as neuroendocrine tolerance. In this review, we first summarize the literature suggesting that alcohol-induced alterations in these hypothalamic systems influence craving and contribute to the development of AUDs. We note that for women, the effects of alcohol on these neuroendocrine stress regulation systems may be influenced by the rhythmic variations of hormones and steroids across the menstrual cycle. Second, we discuss how changes in these systems may indicate progression of AUDs and increased risk of relapse in both sexes. Specifically, neuroendocrine tolerance may contribute to mesocortical sensitization, which in turn may lead to decreased prefrontal inhibitory control of the dopaminergic reward and hypothalamic stress systems. Thus, pharmacological strategies that counteract alcohol-associated changes in hypothalamic and extrahypothalamic stress regulation pathways may slow the development and progression of AUDs.

Reductions in circulating endocannabinoid 2-arachidonoylglycerol levels in healthy human subjects exposed to chronic stressors

Increasing evidence indicates that chronic stress, such as social isolation, plays an important role in the development of a variety of psychiatric and somatic disorders. Meanwhile, chronic stress imposed by prolonged isolation and confinement in the spacecraft is also one of the major concerns for the health of future interplanetary space travelers. Preclinical studies suggest that the peripheral endocannabinoid (eCB) system is involved in the regulation of the stress response and eCB signaling is implicated in the pathogenesis of stress-related diseases. However, there are only few human studies addressing this topic, of which most focusing on patients who have already developed a certain type of disorder. It remains unknown whether chronic stress may affect eCB signaling in healthy humans. A 520-d isolation and confinement study simulating a flight to Mars provided an extraordinary chance to study the effects of prolonged stress in healthy humans. During the study period, the participants lived in confinement and could not meet their families, friends, or strangers for more than 500days. We examined the impact of chronic exposure to isolation and confinement through monitoring their psychological state, brain cortical activity, sympathetic adrenal–medullary system response and eCB signaling response. We observed reduced positive emotion ratings, decreased brain cortical activities and high levels of catecholamine release, indicating that prolonged exposure to isolation and confinement stressors may bring about changes both psychologically and physiologically. Importantly, for eCB signaling response, blood concentrations of eCB 2-arachidonoylglycerol (2-AG), but not anandamide (AEA), were significantly reduced (p<0.001), suggesting that dysregulation of 2-AG signaling might be specifically implicated in the response to chronic stressors.

Rapid stress system drives chemical transfer of fear from sender to receiver.

Humans can register another person’s fear not only with their eyes and ears, but also with their nose. Previous research has demonstrated that exposure to body odors from fearful individuals elicited implicit fear in others. The odor of fearful individuals appears to have a distinctive signature that can be produced relatively rapidly, driven by a physiological mechanism that has remained unexplored in earlier research. The apocrine sweat glands in the armpit that are responsible for chemosignal production contain receptors for adrenalin. We therefore expected that the release of adrenalin through activation of the rapid stress response system (i.e., the sympathetic-adrenal medullary system) is what drives the release of fear sweat, as opposed to activation of the slower stress response system (i.e., hypothalamus-pituitary-adrenal axis). To test this assumption, sweat was sampled while eight participants prepared for a speech. Participants had higher heart rates and produced more armpit sweat in the fast stress condition, compared to baseline and the slow stress condition. Importantly, exposure to sweat from participants in the fast stress condition induced in receivers (N = 31) a simulacrum of the state of the sender, evidenced by the emergence of a fearful facial expression (facial electromyography) and vigilant behavior (i.e., faster classification of emotional facial expressions).

Salivary α-Amylase Reactivity to Laboratory Social Stress With and Without Acute Sleep Restriction

A growing literature suggests that salivary α-amylase (sAA) may serve as a minimally invasive marker of psychophysiological stress-induced activity of the sympathetic-adrenal-medullary system (SAM). Previous inconsistencies in the experimental literature relating sAA response to short sleep duration may be as a result of poor reliability of self-reported sleep time, suggesting that further examination of sAA response following verified sleep loss is required. With regard to the potential usefulness of sAA as a biomarker of psychosocial stress in the laboratory, previous research has also relied primarily on traditional psychosocial stress protocols, including physically present evaluative observers. The present study aimed to examine sAA response following a period of verified acute sleep restriction compared to a rested condition, in addition to examining the sensitivity of sAA response to a laboratory stress protocol that exposed participants to negative social evaluation presented by video relay. One hundred and eight healthy young adults (age 17–22 years; M = 18.39 years, SD = 0.87) completed a laboratory social stress task and provided saliva samples pre- and post-stressor presentation, after a night of partial sleep restriction or a full night’s rest. Marked increases in sAA activity to the video-relayed stressor were observed in both rested and sleep restricted groups. Further, sleep restricted participants exhibited significantly increased basal levels of sAA activity. The data corroborate previous limited data indicating a general upregulation of sAA activity following poor sleep and support previous findings concerning the efficacy of an experimental paradigm that presents laboratory social stress by means of video recording.

Acute psychosocial stress induces differential short-term changes in catecholamine sensitivity of stimulated inflammatory cytokine production.

We have previously shown that psychosocial stress induces acute changes in glucocorticoid (GC) sensitivity of pro-inflammatory cytokine production. However, hormones of the sympathetic adrenal medullary system complement endocrine regulation of inflammatory responses. The current study therefore aimed at investigating the effects of repeated acute stress exposure on catecholamine sensitivity of inflammatory cytokine production. Twenty healthy male participants were subjected to the Trier Social Stress Test on two consecutive days. Blood samples were taken before and repeatedly after stress. Whole blood was stimulated with lipopolysaccharide and incubated with increasing concentrations of epinephrine (E) and norepinephrine (NE) for 18h. Tumor-necrosis-factor (TNF) alpha and interleukin (IL)-6 were measured in culture supernatants. Overall, incubation with E and NE induced dose-dependent suppression of TNF-alpha (NE: F=77.66, p<.001; E: F=63.38, p<.001), and IL-6 production (NE: F=28.79, p<.001; E: F=24.66, p<.001). Acute stress exposure resulted in reduced sensitivity of TNF-alpha (NE: F=6.36, p<.001; E: F=4.86, p=.005), but not IL-6 (NE: F=1.07, p=.38; E: F=0.88, p=.50) to the inhibitory signals of E and NE. No evidence of habituation of these effects was found (all p⩾.22). The present findings extend our knowledge on changes in inflammatory target tissue sensitivity in response to acute psychosocial stress from glucocorticoid-dependent effects to catecholamine-dependent effects. Stress-induced decreases in catecholamine sensitivity thereby suggest intracellular processes aiding in maintaining a healthy endocrine-immune interplay. Longitudinal studies will have to investigate the processes leading from a supposedly beneficial short-term catecholamine resistance in response to acute stress to basal catecholamine resistance observed in relation to negative health outcomes.

Children’s negative emotionality combined with poor self-regulation affects allostatic load in adolescence

The present study examined the concurrent and prospective, longitudinal effects of childhood negative emotionality and self-regulation on allostatic load (AL), a physiological indicator of chronic stress. We hypothesized that negative emotionality in combination with poor self-regulation would predict elevated AL. Mothers reported on children’s emotionality (N = 239, 116 males) at age 9, and self-regulation was measured at age 9 using a standard behavioural index of delay of gratification. AL was measured at ages 9 and 17. The AL measure captured hypothalamic pituitary adrenal axis, sympathetic adrenal medullary system, cardiovascular, and metabolic activity. Our results confirmed that negative emotionality prospectively predicted increases in AL, but only in children with low levels of self-regulation. The findings suggest that the link between negative emotionality and stress physiology is moderated by self-regulation and contribute to understanding the role of negative emotionality in physiological functioning throughout childhood and adolescence.

Childhood cumulative risk and later allostatic load: Mediating role of substance use.

The present study investigated the long-term impact of exposure to poverty-related stressors during childhood on allostatic load, an index of physiological dysregulation, and the potential mediating role of substance use. Participants (n = 162) were rural children from New York State, followed for 8 years (between the ages 9 and 17). Poverty- related stress was computed using the cumulative risk approach, assessing stressors across 9 domains, including environmental, psychosocial, and demographic factors. Allostatic load captured a range of physiological responses, including cardiovascular, hypothalamic pituitary adrenal axis, sympathetic adrenal medullary system, and metabolic activity. Smoking and alcohol/drug use were tested as mediators of the hypothesized childhood risk-adolescent allostatic load relationship. Cumulative risk exposure at age 9 predicted increases in allostatic load 8 years later. Smoking, but not alcohol and drug use, was a significant mediator of the prospective, longitudinal relationship between childhood cumulative risk and adolescent allostatic load. The present paper contributes to the understanding of the role of early life stress in health across the life span and of the mechanisms by which adverse childhood environments impact health as children emerge into early adulthood. This knowledge will have implications for early intervention efforts.