The impact of chronic environmental stressors on growing pigs, Sus scrofa (Part 2): social behaviour

The effects of common and concurrent environmental stressors on the social behaviour of farm animals are poorly understood. Here, we report the results of a multifactorial experiment designed specifically to examine the individual, additive or interactive effects of elevated ammonia, noise and low light (LL) levels on the social behaviour of growing pigs. Social behaviour was measured in terms of the nature, frequency and duration of both initiated and response behaviours for 4 weeks following mixing of the groups. General activity patterns, group cohesion and social discrimination were also examined as a function of the environmental treatments. Elevated concentrations of atmospheric ammonia (～20 v. <5 ppm) and LL intensity (～40 v. 200 lux) had the most pronounced effects, particularly on the nature of social interactions, with pigs under these conditions showing more aggression in the early stages of the experiment. In addition, pigs exposed to a high level of mechanical noise representative of artificial ventilation (～80 v. 40 dB [A]) were less submissive to aggressive acts, while pigs in ～20 ppm ammonia showed more reciprocated aggression when in coincident LL (<40 lux). The results indicate that atmospheric ammonia at commonly experienced concentrations may undermine social stability, particularly in the presence of low lighting, though the mechanisms are currently unknown. These findings have implications for the welfare of growing pigs and hence policy makers and farmers alike, with respect to the improvement of welfare in intensive pig farming.     

Chronic ammonia exposure does not influence hepatic gene expression in growing pigs

Housed pigs are often exposed to elevated concentrations of atmospheric ammonia. This aerial pollutant is widely considered to be an environmental stressor that also predisposes to reduced growth rates and poor health, although evidence to support this view is limited. Hepatic gene expression is very responsive to stress and metabolic effects. Two batches of growing pigs were therefore exposed to a nominal concentration of atmospheric ammonia of either 5 ppm (low) or 20 ppm (high) from 4 weeks of age for 15 weeks. Growth rates were monitored. Samples of liver were taken after slaughter (at ∼19 weeks of age). Samples from the second batch were analysed for global gene expression using 23 K Affymetrix GeneChip porcine genome arrays. Samples from both batches were subsequently tested for five candidate genes using quantitative real-time PCR (qPCR). The array analysis failed to detect any significant changes in hepatic gene expression following chronic exposure to atmospheric ammonia. Animals clustered into two main groups but this was not related to the experimental treatment. There was also no difference in growth rates between groups. The qPCR analyses validated the array results by showing similar fold changes in gene expression to the arrays. They revealed a significant batch effect in expression of lipin 1 (LPIN1), Chemokine (C-X-C motif) ligand 14 (CXCL14), serine dehydratase (SDS) and hepcidin antimicrobial peptide (HAMP). Only CXCL14, a chemotactic cytokine for monocytes, was significantly down-regulated in response to ammonia. As chronic exposure to atmospheric ammonia did not have a clear influence on hepatic gene expression, this finding implies that 20 ppm of atmospheric ammonia did not pose a significant material risk to the health or metabolism of housed pigs.     

Differences in Salivary Alpha-Amylase and Cortisol Responsiveness following Exposure to Electrical Stimulation versus the Trier Social Stress Tests

Background

Cortisol is an essential hormone in the regulation of the stress response along the HPA axis, and salivary cortisol has been used as a measure of free circulating cortisol levels. Recently, salivary alpha-amylase (sAA) has also emerged as a novel biomarker for psychosocial stress responsiveness within the sympathetic adrenomedullary (SAM) system.

Principal Findings

We measured sAA and salivary cortisol in healthy volunteers after exposure to the Trier Social Stress Test (TSST) and electric stimulation stress. One hundred forty-nine healthy volunteers participated in this study. All subjects were exposed to both the TSST and electric stimulation stress on separate days. We measured sAA and salivary cortisol levels three times immediately before, immediately after, and 20 min after the stress challenge. The State (STAI-S) and Trait (STAI-T) versions of the Spielberger Anxiety Inventory test and the Profile of Mood State (POMS) tests were administered to participants before the electrical stimulation and TSST protocols. We also measured HF, LF and LF/HF Heart Rate Variability ratio immediately after electrical stimulation and TSST exposure. Following TSST exposure or electrical stimulation, sAA levels displayed a rapid increase and recovery, returning to baseline levels 20 min after the stress challenge. Salivary cortisol responses showed a delayed increase, which remained significantly elevated from baseline levels 20 min after the stress challenge. Analyses revealed no differences between men and women with regard to their sAA response to the challenges (TSST or electric stimulations), while we found significantly higher salivary cortisol responses to the TSST in females. We also found that younger subjects tended to display higher sAA activity. Salivary cortisol levels were significantly correlated with the strength of the applied electrical stimulation.

Conclusions

These preliminary results suggest that the HPA axis (but not the SAM system) may show differential response patterns to distinct kinds of stressors.     

Social and reproductive conditions modulate urinary cortisol excretion in black tufted-ear marmosets (Callithrix kuhli)

The links between psychosocial stress, social status, reproductive function, and urinary cortisol were assessed in social groups of black tufted-ear marmosets (Callithrix kuhli). Urinary cortisol excretion was monitored in cases of intrafamily conflict (“sibling fights”) and in daughters in four distinct social contexts: in the family group, while housed singly or in same-sex pairs, and while paired with a male pairmate. Cortisol excretion was elevated in participants in intra-family conflict on the day of and the day following the conflict, relative to concentrations a week prior to or following the conflict. Daughters in natal family groups had concentrations of cortisol that did not differ from reproductively active adult females. This finding held for daughters who were either anovulatory or undergoing ovulatory cycles while in the natal family group. Natal family members and male pairmates exerted buffering effects on levels of activity in the hypothalamic pituitary adrenal axis (HPA) in female C. kuhli. Placing females in solitary housing led to significantly increased cortisol excretion. In the 2 months subsequent to pairing with a male partner, excreted cortisol concentrations in females declined significantly. Daughters removed from their natal family group and housed with a sister did not exhibit increased cortisol levels. These data reveal that activity in the (HPA) axis in marmosets is sensitive to psychosocial stressors, and that urinary cortisol can provide a useful quantitative measure of HPA reactivity. As in other callitrichids, delayed breeding in daughters and reproductive anomalies in C. kuhli appear to be mediated by mechanisms other than elevated HPA activity. Am. J. Primatol. 42:253–267, 1997. © 1997 Wiley-Liss, Inc.     

Sex differences in salivary cortisol in response to acute stressors among healthy participants, in recreational or pathological gamblers, and in those with posttraumatic stress disorder

Sex differences in incidence and severity of some stress-related, neuropsychiatric disorders are often reported to favor men, suggesting that women may be more vulnerable to aberrant hypothalamic-pituitary-adrenal (HPA) axis responses to stress. In this review, we discuss several investigations that we, and others, have conducted assessing salivary cortisol as a measure of HPA function. We have examined basal cortisol among healthy men and women and also following acute exposure to stressors. Among healthy participants, men had higher basal cortisol levels than did women. In response to acute stressors, such as carbon dioxide or noise, respectively, cortisol levels were comparable between men and women or higher among women. We have also examined cortisol levels among those with problem eating, gambling, or posttraumatic stress disorder (PTSD). Women with restrained eating habits have higher basal cortisol levels than do women without restrained eating habits. Pathological gamblers have more aberrant stress response to gambling stimuli than do recreational gamblers, and these effects are more prominent among men than women. Men who have motor vehicle accident related PTSD, demonstrate more aberrant cortisol function, than do their female counterparts. Although these sex differences in cortisol seem to vary with type of stress exposure and/or pathophysiological status of the individual, other hormones may influence cortisol response. To address this, cortisol levels among boys and girls with different stress-related experiences, will be the subject of future investigation.     

Noninvasive technique for the repeated sampling of salivary free cortisol in awake,unrestrained squirrel monkeys

The use of noninvasive measures of hypothalamic-pituitary-adrenal (HPA) axis function is of growing interest among preclinical and clinical investigators. This report describes a method for the repeated assessment of salivary free cortisol in awake, unrestrained squirrel monkeys (Saimiri sciureus) based on a saliva sampling technique previously developed for rhesus monkeys. Individually housed adult male squirrel monkeys were trained to chew on dental rope attached to a pole, from which saliva was extracted by centrifugation and analyzed for cortisol by radioimmunoassay (RIA). Eight of nine monkeys readily acquired the task, reliably providing adequate saliva samples for the assay. Salivary free cortisol levels were examined in these subjects under basal conditions and in response to two types of neuroendocrine challenge. Levels of salivary free cortisol showed relatively low intra- and interindividual variability, with mean individual morning levels ranging between 17.1 and 37.9 microg/dl. Squirrel monkeys demonstrated a consistent daily rhythm in salivary free cortisol ranging from a high of 27.4 +/- 5.2 microg/dl (mean +/- SEM) at 12 P.M. to a low of 7.5 +/- 1.6 microg/dl at 6 P.M. Intravenous (IV) challenges with 1 microg/kg ACTH, or 10 and 50 microg/kg CRF resulted in significant increases in salivary free cortisol. The described sampling technique provides a reliable and sensitive means for repeated measurement of HPA activity in unrestrained, awake squirrel monkeys. In addition, our findings illustrate several features of HPA system rhythmicity and reactivity using salivary cortisol instead of blood plasma or serum.     

Effects of Artificial Dawn and Morning Blue Light on Daytime Cognitive Performance,Well-being,Cortisol and Melatonin Levels

Light exposure elicits numerous effects on human physiology and behavior, such as better cognitive performance and mood. Here we investigated the role of morning light exposure as a countermeasure for impaired cognitive performance and mood under sleep restriction (SR). Seventeen participants took part of a 48h laboratory protocol, during which three different light settings (separated by 2?wks) were administered each morning after two 6-h sleep restriction nights: a blue monochromatic LED (light-emitting diode) light condition (BL; 100?lux at 470?nm for 20?min) starting 2?h after scheduled wake-up time, a dawn-simulating light (DsL) starting 30?min before and ending 20?min after scheduled wake-up time (polychromatic light gradually increasing from 0 to 250?lux), and a dim light (DL) condition for 2?h beginning upon scheduled wake time (<8?lux). Cognitive tasks were performed every 2?h during scheduled wakefulness, and questionnaires were administered hourly to assess subjective sleepiness, mood, and well-being. Salivary melatonin and cortisol were collected throughout scheduled wakefulness in regular intervals, and the effects on melatonin were measured after only one light pulse. Following the first SR, analysis of the time course of cognitive performance during scheduled wakefulness indicated a decrease following DL, whereas it remained stable following BL and significantly improved after DsL. Cognitive performance levels during the second day after SR were not significantly affected by the different light conditions. However, after both SR nights, mood and well-being were significantly enhanced after exposure to morning DsL compared with DL and BL. Melatonin onset occurred earlier after morning BL exposure, than after morning DsL and DL, whereas salivary cortisol levels were higher at wake-up time after DsL compared with BL and DL. Our data indicate that exposure to an artificial morning dawn simulation light improves subjective well-being, mood, and cognitive performance, as compared with DL and BL, with minimal impact on circadian phase. Thus, DsL may provide an effective strategy for enhancing cognitive performance, well-being, and mood under mild sleep restriction.     

Increased Cortisol Bioavailability,Abdominal Obesity,and the Metabolic Syndrome in Obese Women

Objective: This study was conducted to obtain a detailed profile of hypothalamo‐pituitary‐adrenal (HPA) axis activity and reactivity and its differential relationships with body fat distribution and total fat mass in premenopausal obese women. Research Methods and Procedures: Cortisol responses to stimulation (awakening, food intake, exercise) and suppression (0.25 mg dexamethasone), cortisol metabolism, and tissue sensitivity to glucocorticoids were studied in 53 premenopausal obese women grouped according to their waist‐to hip ratio: women with abdominal body fat distribution (A‐BFD; n = 31) and women with peripheral fat distribution (P‐BFD; n = 22). Results: Comparatively, A‐BFD women had 1) lower awakening salivary cortisol levels; 2) increased salivary responsiveness to a standardized lunch; 3) similar pituitary sensitivity to dexamethasone but decreased sensitivity of monocytes to dexamethasone; 4) similar 24‐hour urinary free cortisol but increased 24‐hour urinary ratio of cortisone‐to‐cortisol; and 5) no difference in corticosteroid binding protein parameters. Discussion: Although abdominal obesity is not very different from generalized obesity in terms of HPA function, subtle variations in HPA axis activity and reactivity are evidenced in A‐BFD premenopausal obese women.     

Association of salivary steroid hormones and their ratios with time-domain heart rate variability indices in healthy individuals

BackgroundStress system consists of the hypothalamicpituitary-adrenal (HPA) axis and the locus caeruleus/norepinephrine-autonomic nervous system (ANS). Traditionally, HPA axis activity is evaluated by measuring its end-product cortisol, while the activity of ANS is assessed using heart rate variability (HRV) indices. Alterations in cortisol levels and HRV measures during laboratory-based stress tasks were extensively studied in previous research. However, scarce data exist on the associations of HRV measures with the levels of other adrenal steroid hormones under baseline conditions. Thus, we aimed to evaluate the activity of the HPA axis by measuring salivary cortisol, cortisone, dehydroepiandrosterone (DHEA) levels, and their ratios and to examine its association with HRV measures in a sample of healthy young and middle-aged adults.MethodsFor each participant (n=40), three data collection sessions taking place at the same time of the day were scheduled within five working days. Participants completed a self-reported questionnaire on sociodemographic and lifestyle characteristics, filled out t h e Perceived Stress Scale and State-Trait Anxiety Inventory. Also, saliva samples were collected, and physiological measures, including resting HR and HRV, were recorded during three data collection sessions.ResultsStatistically significant associations between diminished parasympathetic vagal tone evaluated by time domain HRV measures and higher salivary cortisol, lower DHEA levels, as well as decreased DHEA to cortisol ratio, were found. Also, physiological stress indicators (i.e., HRV) showed greater intraindividual stability compared with biochemical biomarkers (i.e., salivary steroid hormones) within five days.ConclusionsOur findings suggest that both cortisol and DHEA mediate the link between two stress-sensitive homeostatic systems.     

Endogenous monoamine oxidase inhibitory activity and HPA activation in the pig

Previously we have shown that an increase in endogenous monoamine oxidase A inhibitory activity (MAO-AI), measured in human saliva, both precedes and predicts psychological stress-induced activation of the hypothalamic pituitary adrenal (HPA) axis, as determined by the cortisol response. We now report the relationship between endogenous MAO-AI and the cortisol response in the plasma of prepubertal pigs (n=5 or 6) under two experimental paradigms of HPA activation. In the first condition, pigs were physically restrained (snaring) for 15 minutes. Blood samples were taken from indwelling catheters at intervals before and after snaring (a sampling period of about 1 hour), and at the same time intervals on a separate day to provide baseline measures. Both cortisol concentration and percentage MAO-AI were determined in each plasma sample. There was a pronounced cortisol response on the snaring day (cortisol peaked 30 minutes after the start of the snaring). There was also a significant MAO-AI response to snaring which peaked 15 minutes after the start of the stress challenge. In the second experimental paradigm, bacterial endotoxin (LPS: 20microg/pig) was used to induce HPA activation and plasma cortisol and MAO-AI were determined. This time, however, the cortisol response was not preceded by any change in MAO-AI. We conclude that generation of MAO-AI, which is associated with HPA activation induced by psychological stress, is not a component of the pathways involved in immunological stimulation of the HPA axis.     

Expression of steroidogenic enzyme messenger ribonucleic acid and cortisol production in adrenocortical cells isolated from halothane-sensitive and halothane-resistant pigs

Stress susceptibility in pigs is inherited by a single recessive gene (Hal(n)), and homozygous individuals can be identified by exposure to halothane anesthesia. Previous studies have shown that in stress-susceptible pigs, exposure to a high ambient temperature resulted in a twofold increase in corticotropin (ACTH) and lower plasma cortisol. To determine whether there is a fundamental difference in adrenocortical function between halothane-sensitive (HAL-S) and halothane-resistant (HAL-R) pigs, independent of other factors influencing the hypothalamic-pituitary-adrenal (HPA) axis, we compared cortisol responses to ACTH and 8-bromo-cyclic AMP (8-Br-cAMP) in HAL-S and HAL-R pig adrenocortical cells in vitro. We also determined directly the accumulation of four different mRNAs encoding cholesterol side-chain cleavage cytochrome P450 (P450(scc)), 17alpha-hydroxylase cytochrome P450 (P450(17alpha)), 21-hydroxylase cytochrome P450 (P450(c21)) and 11beta-hydroxylase cytochrome P450 (P450(11beta)) in HAL-S pig adrenal cells and compared them to HAL-R pigs. A time- and dose-dependent increase in medium content of cortisol and cAMP was observed after ACTH treatment. 8-Br-cAMP also caused a time- and dose-dependent increase in cortisol production in the medium. Addition of ACTH or 8-Br-cAMP to HAL-S and HAL-R male Lanyu small-ear miniature pig adrenocortical cells increased cortisol production in a dose- and time-related manner. However, cells isolated from HAL-S pigs had a lower cortisol production in response to ACTH or 8-Br-cAMP compared to those from HAL-R pigs. Treatment of cultured cells with 8-Br-cAMP (0.5 mM) for 18 h resulted in a significant increase in P450(scc), P450(17alpha), P450(c21), and P450(11beta) mRNA levels. In the absence of 8-Br-cAMP, the four genes were expressed constitutively in both HAL-S and HAL-R pig adrenal cells. Densitometric scanning of the autoradiograph indicated that the relative amounts of P450(scc) and P450(17(alpha)) mRNAs in HAL-S pig adrenal cells were between 48% and 53% of those detected in HAL-R pig adrenal cells (P < 0.05). No difference in the amounts of P450(c21) and P450(11beta) was seen in HAL-S and HAL-R pig adrenal cells. Addition of 8-Br-cAMP (0.5 mM) resulted in a uniform increase in the levels of all four P450 mRNAs in both HAL-S and HAL-R pig adrenal cells. However, the amounts of P450(scc) mRNA in HAL-S pig adrenal cells were 67% (P < 0.05) of those measured in HAL-R pig adrenal cells, whereas the amounts of P450(17alpha ), P450(c21), and P450(11beta) mRNAs were similar in these cells. Our data suggest an HPA axis defect in HAL-S pigs at the adrenal level. This defect appears to be at the level of P450scc gene expression, which could be partially related to reduced cortisol production by ACTH stimulation.     

Corticosteroid Binding Globulin Gene Polymorphism Influences Cortisol Driven Fat Distribution in Obese Women

Hypothalamo‐pituitary‐adrenal axis has been reported to influence fat mass distribution in obesity. We investigated the hypothesis that corticosteroid‐binding globulin (CBG) polymorphism could influence obesity, metabolic, or hypothalamo‐pituitary adrenal (HPA) axis activity parameters. In 44 obese pre‐menopausal women, a microsatellite located within the CBG gene was analyzed, providing three genotypes: 86/86 (n = 29), 86/90 (n = 14), and 90/90 (n = 1). No significant difference was found for obesity, metabolic, and HPA axis activity parameters between the genotypes 86/86 and 86/90. Looking for differences in correlations between HPA axis activity parameters and obesity or metabolic parameters between the two genotypes, genotype 86/90 showed a strong correlation between salivary cortisol after dexamethasone (0.25 mg) suppression test and waist‐to‐hip ratio (r = ?0.84, p = 0.0007), whereas this correlation was weaker for genotype 86/86 (r = ?0.34, p = 0.09). These data were completed with an analysis of the BclI polymorphism of the glucocorticoid receptor (GR) gene. There was an association between this GR polymorphism and both awakening salivary cortisol and postdexamethasone salivary cortisol but no association for obesity or metabolic parameters. We concluded that CBG gene polymorphisms might modulate the influence of the HPA axis on the fat mass distribution in this population.     

Health and immune traits of Basque and Large White pigs housed in a conventional or enriched environment

Since decades, production traits such as growth rate, feed efficiency or body composition have been drastically increased in pigs by genetic selection. Whether this selection impacted animal robustness is still unclear. In this study, we compared Large White (LW) pigs, a breed submitted to intense genetic selection for production traits, and Basque (B) pigs, a local rustic breed, reared in two different housing environments (conventional v. enriched). Adaptation to housing conditions among each breed was evaluated at the level of endocrine and immune traits. These are known to be impacted by housing conditions and breed; however, the interaction effects between genotype and environment are less described. Animals (20 per breed and housing environment) entered the experiment at 35 kg of live weight. Levels of cortisol, acute-phase inflammatory proteins, immunoglobulins and hydrogen peroxide, blood formula, lymphocyte proliferation and in-vitro cytokine expression were measured at ∼115 kg of live weight. Animals were checked for skin injuries during the growing period. At slaughter, at the average live weight of 145 kg, carcasses were examined for pathological conditions of the respiratory tract. The major result was that the two breeds exhibited differences in response to the housing environment. Among the 24 sanitary, endocrine or immune traits investigated, the housing conditions affected eight variables in both breeds (salivary cortisol at 0700 and 1900 h, severity of pneumonia at slaughter) or only in B pigs (severe skin lesions) or LW pigs (salivary cortisol at 1500 h, granulocyte numbers and lymphocyte/granulocyte ratio and lymphocyte proliferation). These observations strengthen the hypothesis that selection for high meat production level might be associated with an increased susceptibility of animals to environmental stressors.     

Behavioural,endocrine and immune responses to repeated social stress in pregnant gilts

Pregnant sows are exposed to various stressors in intensive pig husbandry that may have negative consequences on their health, reproductive performances and welfare. Social stress is one of these challenges, because gestating sows have to be housed in groups according to EU guidelines (2001/88/CE). The purpose of this study was to determine the consequences of repeated social stress in pregnant female pigs on their behavioural, endocrine and immunological responses and on pregnancy outcome. Pregnant gilts were submitted to a repeated social stress procedure induced by housing unfamiliar gilts in pairs changed twice a week between days 77 and 105 of gestation (S group, n = 18). Control gilts were housed in stable pairs during the same period (C group, n = 18). Agonistic behaviour was observed during the first 3 h after each grouping. Skin lesions were numbered 2 h after each grouping. Salivary cortisol was measured before and repeatedly during the 4 weeks of grouping. Gilts were immunized against keyhole limpet haemocyanin (KLH) on days 81 and 95 of gestation. Immunoglobulins G against KLH, proliferative responses to concanavalin A, lipopolysaccharide, pokeweed mitogen and KLH and peripheral blood leukocyte numbers were evaluated 1 week before the first grouping and 3 days after the last one. Agonistic interactions and skin lesions were observed in S gilts at each grouping, although there was a decline between the first and the last grouping (P < 0.05). The repeated social stress induced a sustained endocrine response as shown by elevated salivary cortisol levels from 1 to 48 h after grouping in S gilts compared to C gilts. The cellular as well as the humoral immunity and the leukocyte numbers were not influenced by social stress. Gestation length tended to be shorter in S gilts (P = 0.09), but litter size, piglet weight or mortality at birth were not affected. Variability of the response of S gilts to groupings was partly explained by their average success value determined according to the outcome (defeat or win) of all the groupings. In conclusion, our study demonstrates that the application of repeated social stress to pregnant gilts during the last third of their gestation repeatedly activates their hypothalamo–pituitary–adrenal axis but does not impair their immune function and pregnancy outcome.     

Glucose but not protein or fat load amplifies the cortisol response to psychosocial stress

We previously reported that glucose intake amplifies cortisol response to psychosocial stress and smoking in healthy young men, while low blood glucose levels prevented the stress-induced activation of the hypothalamus pituitary adrenal (HPA) axis. However, it remains unknown whether this modulation is specific for glucose load or a more common effect of energy availability. To elucidate this question, 37 healthy men, who fasted for at least 8 h before the experiment, were randomly assigned to four experimental groups, who received glucose (n = 8), protein (n = 10), fat (n = 10), and water (n = 9), one h before their exposure to the Trier Social Stress Test (TSST). Blood glucose levels were measured at baseline and following stress, while salivary cortisol was assessed repeatedly measured before after the TSST. The results show that both absolute cortisol levels and net cortisol increase were greater in the glucose group in comparison to the other groups (F(3,33) = 3.00, P < 0.05 and F(3,33) = 3.08, P < 0.05, respectively. No group differences were observed with respect to perceived stress and mood. Furthermore, the cortisol response was positively correlated with blood glucose changes (r = 0.49, P < 0.002). In conclusion, the results suggest a central mechanism responsible for regulation of energy balance and HPA axis activation, rather than peripheral mechanisms. We thus recommend controlling for blood glucose levels when studying HPA axis responsiveness.     

Cortisol responses to mental stress and the progression of coronary artery calcification in healthy men and women

Background

Psychosocial stress is a risk factor for coronary heart disease (CHD). The mechanisms are incompletely understood, although dysfunction of the hypothalamic pituitary adrenal (HPA) axis might be involved. We examined the association between cortisol responses to laboratory-induced mental stress and the progression of coronary artery calcification (CAC).

Methods and Results

Participants were 466 healthy men and women (mean age = 62.7±5.6 yrs), without history or objective signs of CHD, drawn from the Whitehall II epidemiological cohort. At the baseline assessment salivary cortisol was measured in response to mental stressors, consisting of a 5-min Stroop task and a 5-min mirror tracing task. CAC was measured at baseline and at 3 years follow up using electron beam computed tomography. CAC progression was defined as an increase >10 Agatston units between baseline and follow up. 38.2% of the sample demonstrated CAC progression over the 3 years follow up. There was considerable variation in the cortisol stress response, with approximately 40% of the sample responding to the stress tasks with an increase in cortisol of at least 1 mmol/l. There was an association between cortisol stress reactivity (per SD) and CAC progression (odds ratio = 1.27, 95% CI, 1.02–1.60) after adjustments for age, sex, pre-stress cortisol, employment grade, smoking, resting systolic BP, fibrinogen, body mass index, and use of statins. There was no association between systolic blood pressure reactivity and CAC progression (odds ratio per SD increase = 1.03, 95% CI, 0.85–1.24). Other independent predictors of CAC progression included age, male sex, smoking, resting systolic blood pressure, and fibrinogen.

Conclusion

Results demonstrate an association between heightened cortisol reactivity to stress and CAC progression. These data support the notion that cortisol reactivity, an index of HPA function, is one of the possible mechanisms through which psychosocial stress may influence the risk of CHD.     

Diurnal salivary cortisol is associated with body mass index and waist circumference: The multiethnic study of atherosclerosis

Objective:

Neuroendocrine abnormalities, such as activation of the hypothalamic‐pituitary‐adrenal (HPA) axis, are associated with obesity; however, few large‐scale population‐based studies have examined HPA axis and markers of obesity. We examined the cross‐sectional association of the cortisol awakening response (CAR) and diurnal salivary cortisol curve with obesity.

Design and Methods:

The Multiethnic Study of Atherosclerosis Stress Study includes 1,002 White, Hispanic, and Black men and women (mean age 65 ± 9.8 years) who collected up to 18 salivary cortisol samples over 3 days. Cortisol profiles were modeled using regression spline models that incorporated random parameters for subject‐specific effects. Cortisol curve measures included awakening cortisol, CAR (awakening to 30‐min postawakening), early decline (30 min to 2‐h postawakening), late decline (2‐h postawakening to bedtime), and the corresponding areas under the curve (AUC). Body mass index (BMI) and waist circumference (WC) were used to estimate adiposity.

Results:

For the entire cohort, both BMI and WC were negatively correlated with awakening cortisol (P < 0.05), AUC during awakening rise, and early decline and positively correlated to the early decline slope (P < 0.05) after adjustments for age, race/ethnicity, gender, diabetes status, socioeconomic status, β‐blockers, steroids, hormone replacement therapy, and smoking status. No heterogeneities of effects were observed by gender, age, and race/ethnicity.

Conclusions:

Higher BMI and WC are associated with neuroendocrine dysregulation, which is present in a large population sample, and only partially explained by other covariates.     

Cortisol Response to Repeated Psychosocial Stress

Psychosocial stress plays a major role in the etiology and the course of mental disorders that often show an altered activation of the hypothalamus–pituitary–adrenal (HPA) axis. The Trier Social Stress Test (TSST) reliably activates the HPA axis and reflects real life stress exposure. However, habituation may confound the results of clinical trials that apply TSST. The present study investigates the cortisol response after repeated psychosocial stress induction with short-term and long-term intervals between repeated testing sessions. Forty-one healthy subjects were exposed to the TSST four times with an interval of 24 h between the first and the second testing session (t1 and t2). The 3rd and the 4th testing session (t3 and t4) were also separated by a 24-hour interval whereas there were 10 weeks between t2 and t3. A significant decrease in the salivary cortisol responses was noticed from testing session t1 to t2 as well as from testing session t3 to t4. By contrast, there were no differences in the HPA axis reactivity between testing session t2 and t3. Our results demonstrated the habituation of the HPA axis to a standardized psychosocial stress test when testing was repeated after 24 h. By contrast, a renewed challenge with a ten-week-interval in-between activated the HPA axis in a similar manner as before. It is suggested that studies designed to investigate the HPA axis activity under repeated psychosocial stress conditions should apply the TSST three times in order to separate habituation from intervention effects.     

The Cortisol Paradox of Trauma-Related Disorders: Lower Phasic Responses but Higher Tonic Levels of Cortisol Are Associated with Sexual Abuse in Childhood

Objectives

Inconsistent findings exist for the activity of the hypothalamic-pituitary-adrenal (HPA) axis in patients with stress related disorders. Recent studies point towards early life stress as a potential modulator.

Methods

We investigated the impact of childhood sexual abuse on phasic (saliva cortisol reactivity) and tonic (hair cortisol) regulation. Furthermore, we assessed predictors on cortisol accumulation in hair. Women (N = 43) with stress-related disorders underwent a standardized assessment of idiographic adverse and traumatic experiences and psychopathology, while measuring salivary cortisol and, heart rate and blood pressure.

Results

Comparing women with and without childhood sexual abuse revealed lower rates of responders and distinct levels of salivary cortisol to the interview in conjunction with a lower heart rate for the abused group. Childhood adversities, traumatic experiences, and depression contributed to higher hair cortisol levels.

Conclusions

Our finding of lower response rate and distinct salivary cortisol pattern in individuals with childhood sexual abuse compared to individuals without early sexual abuse supports the role of environmental programming for the HPA axis. Both, childhood adversities and traumatic stress emerge as crucial factors for long-term cortisol secretion. Lower or suppressed phasic cortisol responses to trauma-related stimuli may therefore be associated with higher tonic values. Thus, early exposure to adversities may result in a biological distinct phenotype in adult patients with stress-related disorders.