Hypothalamic-pituitary-adrenocortical System Research Articles

Neuroadaptive Biochemical Mechanisms of Remote Ischemic Conditioning

This review summarizes the currently known biochemical neuroadaptive mechanisms of remote ischemic conditioning. In particular, it focuses on the significance of the pro-adaptive effects of remote ischemic conditioning which allow for the prevention of the neurological and cognitive impairments associated with hippocampal dysregulation after brain damage. The neuroimmunohumoral pathway transmitting a conditioning stimulus, as well as the molecular basis of the early and delayed phases of neuroprotection, including anti-apoptotic, anti-oxidant, and anti-inflammatory components, are also outlined. Based on the close interplay between the effects of ischemia, especially those mediated by interaction of hypoxia-inducible factors (HIFs) and steroid hormones, the involvement of the hypothalamic–pituitary–adrenocortical system in remote ischemic conditioning is also discussed.

Peripheral corticotropin-releasing hormone may protect the gastric musosa against indometacin-induced injury through involvement of glucocorticoids.

The hypothalamic-pituitary-adrenocortical (HPA) system is a key hormonal branch of the brain-gut axis in stress and corticotropin-releasing hormone (CRH) is a principal stimulator of the HPA system. According to our finding activation of the HPA system has gastroprotective role in stress and CRH may protect the gastric mucosa against stress-induced injury through involvement of glucocorticoids. To extend this idea to indomethacin-induced gastric injury in the present work we studied whether CRH may protect the gastric mucosa against ulcerogenic action of indomethacin (IM) through involvement of glucocorticoids. CRH administration (1.25 μg/kg and 2.5 μg/kg, i.p.) markedly, dose-dependently, increased plasma corticosterone level and significantly, dose-dependently, suppressed the occurrence of gastric erosion induced by IM (35 mg/kg, s.c.) in conscious rats. To estimate the role of glucocorticoids in CRH-induced gastroprotection, the effect of CRH (1.25 μg/kg) on the IM-induced gastric erosion was studied after acute reduction of corticosterone release by metyrapone (30 mg/kg, i.p., 30 min before CRH administration) or by CRH receptor type 1 antagonist NBI 27914 (10 mg/kg, i.p., 15 min before CRH administration) and also after occupation of glucocorticoid receptors by their antagonist RU-38486 (20 mg/kg, i.p., 2 h before CRH administration). The effects were compared with those in control rats without acute reduction of corticosterone release or occupation of glucocorticoid receptors. Both metyrapone and NBI 27914 injected shortly before CRH administration caused an inhibition of CRH-induced corticosterone response and prevented protective effect of CRH on the gastric mucosa against the IM-induced erosion. The gastroprotective effect of CRH was also eliminated by the pretreatment with glucocorticoid receptor antagonist RU-38486. The results obtained suggest that exogenous CRH may protect the gastric mucosa against IM-induced gastric injury through involvement of glucocorticoids.

Evaluation of Neuroendocrine and Immunological Parameters in Animals Following Chronic Combined Exposure to Xenobiotics

Background: A high prevalence of chromium and benzene compounds in the environment associated with motor vehicle and industrial operations arouses interest in the study of these xenobiotics in a long-term experiment. The objective of this work was to analyze effects of a chronic combined exposure to chromium and benzene on the hypothalamic-pituitary-adrenocortical (HPA) and immune systems of male Wistar rats. Materials and methods: Eighty male Wistar rats were administered potassium dichromate and benzene with drinking water in doses equaling one maximum permissible concentration (MPC) during 135 days. The hypothalamus, pituitary gland, adrenal glands, thymus, and spleen were then studied using morphometric, histological, and electron microscopy methods. The streptavidin-biotin peroxidase method was used to determine the expression of pro-apoptotic protein p53 and anti-apoptotic protein bcl2. We also measured the body, thymus and spleen weights of animals, nucleated cell counts in the thymus, spleen, and bone marrow and evaluated the cellular composition of the spleen and bone marrow as well as spontaneous and concanavalin A-induced secretion of interferon gamma (IFN-γ), IL-4, IL-6, and IL-10 cytokines by splenocytes. Results: We established an adverse effect of the exposure on the HPA function expressed in the activation of its secretory activity, blocking the release of hypothalamic neuropeptides at the level of the neurohypophysis and leading to ultrastructural damage to the neurosecretory cells of the hypothalamus, pituitary adenocytes and adrenal cortical cells, as well as in an increase in the programmed death of thymocytes. We also observed a decrease in the thymus weight and thymocyte counts and a complex of structural and functional changes indicating the status of its accidental involution in the exposed rats. The revealed decrease in the splenocyte count in the experimental group was accompanied by an increase in the size of the white spleen pulp. An increase in the induced production of the main immunoregulatory cytokines IFN-γ and IL-4 by splenocytes was found. Conclusion: Our findings can be used to analyze impairments of the HPA and immune systems in workers with a chronic combined exposure to benzene and chromium compounds in the occupational setting.

Prenatal Introduction of Dexamethasone Causes Disruption of Glucocorticoid Feedback Associated with a Change in the Amount of Corticosteroid Receptors in Extrahypothalamic Brain Structures of Adult Rats

As are other artificial glucocorticoids, dexamethasone is widely used in everyday obstetric practice. The threat of termination of pregnancy is an indication for the use of glucocorticoids. However, there is evidence that the introduction of glucocorticoids during pregnancy can lead to impaired brain development and behavior of offspring that can be caused by a change in the activity of the hypothalamic–pituitary–adrenocortical system (HPAS) due to past effects. The aim of the present work was to study the effect of the introduction of synthetic hormone dexamethasone at the 14th–16th (DM14–16) and 17th–19th (DM17–19) days of prenatal ontogenesis on the stress reactivity of the HPAS in adult 3-month-old rats, as well as on the level of gluco- (GR) and mineralocorticoid (MR) receptors in the most vulnerable areas of the brain (hippocampus and neocortex). Significant intergroup differences in the dynamics of a change in the level of corticosterone in the blood of adult rats in response to a weak stress effect (rapid stress reactivity test) were detected. Using the immunohistochemical method, changes in the expression (the amount of immunopositive cells) of GR and MR were studied in CA1 field and dentate gyrus (DG) of the hippocampus, as well as in second and fifth neocortex layers in adult male rats. In animals of the DM14–16 group, a significant decrease in the number of cells intensively stained using antibodies to GR in CA1 field, hippocampus DG, and neocortex layer V (to 24.5, 32.4, and 5.5%, respectively) as compared with the control were observed. The introduction of dexamethasone at the 17th–19th day of gestation also led to a decrease in the amount of intensively stained GR-immunopositive cells in the hippocampus CA1 field and neocortex layer V (to 31.9 and 35.7%, respectively), but to a lesser degree than in animals from the group DM14–16. A trend toward a decrease in the number of GR-positive cells is accompanied by an increase in immunoreactivity of the cells to MR. Thus, the introduction of dexamethasone at different periods of prenatal ontogenesis modifies the work of gluco- and mineralocorticoid receptors; however, the degree, localization, and direction of these changes differ depending on the time of the effect.

Validation of an online version of the Trier Social Stress Test in a study of adolescents

IntroductionThe Trier Social Stress Test (TSST) is the most widely used protocol for activating a stress response of the hypothalamic-pituitary-adrenocortical (HPA) axis and other stress-mediating systems. A number of variants of the TSST exist, including ones for children, groups, and virtual reality. All of these versions, though, require in-person assessment. The COVID-19 pandemic has made in-person assessment impossible or extremely difficult and potentially dangerous. The purpose of this study was to validate a completely remote, online, version of the TSST for children. MethodA sample of 68 (27 female) 15- and 16-year old participants were administered the TSST-Online (TSST-OL) during the late afternoon hours (3–6 p.m. start time). The participants, judges (one male, one female), and experimenter (female) all joined the assessment from their own homes via the online platform, ZOOM™. Two sessions were conducted, one to obtain consent, explain procedures, work with the family to arrange the computer and room set-up for the TSST-OL and one within two weeks to conduct the procedure. The participants were trained to take their own saliva samples and a saliva sampling kit was mailed to the home in between the first and second session. The samples were then mailed to the researchers within a day of collection. The participant was observed during saliva collection to determine correct procedures were followed. Salivary cortisol, salivary α-amylase and self-reports of stress were measured multiple times over the second session. ResultsrmANOVAs yielded a significant effect of trials, for cortisol, F(1.37,90.46) = 15.13, p = .001, sAA, F(2.75,146.68) = 6.91, p = .001, and self-rated stress, F(3.43,222.69) = 118.73, p = .001. There were no significant sex by trials interactions for any measure, although females reported more stress than males, F(1,65) = 9.14, p = .004. For cortisol, from baseline to expected peak (30 min after the onset of speech preparation), the Cohen’s effect size was dz = 0.57. Using 1.5 nmol/l (or 0.54 μg/dl) as the criterion for a response (Miller, Plessow, Kirschaum, & Stalder, 2013), 63% of the participants produced a significant increase in cortisol. ConclusionsThe responses to the TSST-OL are consistent with in-person responses among children and adolescents (see recent meta-analysis (Seddon et al., 2020). The protocol is a viable way of assessing reactivity of the HPA axis and other stress systems without needing to bring the participant into the research laboratory. This method will be useful during periods of widespread infection. It should also work to study populations who all live too far from the research laboratory to be assessed in person.

Зміни активності ангіотензинперетворюючого ферменту в структурах гіпоталамо-гіпофізарно-адренокортикальної системи та функції кори надниркових залоз щурів під дією метанандаміду

Мета роботи — дослідити вплив метанандаміду — метаболічно стійкого похідного ендоканабіноїду N-арахідоноїлетаноламіну на активність ангіотензинперетворюючого ферменту (АПФ) у центрах регуляції гіпоталамо-гіпофізарно-адренокортикальної системи (ГГАС), а також на рівень кортикостероїдів у плазмі крові щурів. Матеріал і методи. Активність АПФ у гіпоталамусі, аденогіпофізі, надниркових залозах і плазмі крові щурів визначали за допомогою флуориметричного методу, використовуючи як субстрат Benzoyl-Gly-His-Leu (Sigma, США). Вміст 11-гідроксикортикостероїдів (11-ОКС) у плазмі крові щурів встановлювали із застосуванням флуориметричного мікрометоду. Результати. Через 1 годину після одноразового введення інтактним щурам метанандаміду в дозах 0,2 мг/кг і 0,02 мг/кг активність АПФ у центральних ланках ГГАС — гіпоталамусі та аденогіпофізі підвищувалася, активність АПФ унадниркових залозах та активність циркулюючого в крові ферменту знижувалися. Після одноразового введення інтактним щурам метанандаміду в дозі 0,2 мг/кг виявлено підвищення рівня 11-ОКС у плазмі крові щурів, введення метанандаміду в низькій дозі — 0,02 мг/кг не призводило до вірогідних змін рівня кортикостероїдів у крові тварин. Висновки. Екзогенні канабіноїди модулюють активність ангіотензинової системи в різних ланках ГГАС, стимулюючи активність АПФ у гіпоталамусі й аденогіпофізі та знижуючи активність ферментув надниркових залозах і плазмі крові через 1 годину після одноразового введення метанандаміду інтактним щурам. Через кортикотропін-рилізинг активність ангіотензинів гіпоталамуса та аденогіпофіза підвищення активності АПФ у цих структурах може бути одним із важливих чинників активації ГГАС, зокрема синтезу кортикостероїдів, спричиненого одноразовим введенням метанандаміду у високих дозах.

Social Buffering of Stress in Development: A Career Perspective

This review provides a broad overview of my research group’s work on social buffering in human development in the context of the field. Much of the focus is on social buffering of the hypothalamic-pituitary-adrenocortical (HPA) system, one of the two major arms of the mammalian stress system. This focus reflects the centrality of the HPA system in research on social buffering in the fields of developmental psychobiology and developmental science. However, buffering of the cardiovascular and autonomic nervous system is also discussed. The central developmental question in this area derives from attachment theory, which argues that the infant’s experience of stress and arousal regulation in the context of her early attachment relationships is not an immature form of social buffering experienced in adulthood but rather the foundation out of which individual differences in the capacity to gain stress relief from social partners emerges. The emergence of social buffering in infancy, changes in social buffering throughout childhood and adolescence, the influence of early experience on later individual differences in social buffering, and critical gaps in our knowledge are described.

The Realization of the Brain-Gut Interactions with Corticotropin-Releasing Factor and Glucocorticoids.

BackgroundThe brain and the gut interact bi-directionally through the brain-gut axis. The interaction is mediated by the autonomic nervous system and the hypothalamic-pituitary-adrenocortical (HPA) system. The first brilliant demonstration of the brain-gut interactions was the cephalic phase of gastric and pancreatic secretion discovered by Ivan Pavlov, the first physiologist who was awarded the Nobel Prize for Physiology or Medicine in 1904. This review aims to identify the HPA system as a key hormonal branch of the brain-gut axis in stress.MethodsWe first outlined main components of the brain-gut axis and then focused on the HPA system as a key hormonal branch of the brain-gut axis in stress. We undertook a structured search of bibliographic databases for peer-reviewed research literature using a focused review question.ResultsSeventy-one articles were included in the review, the eleventh of them were articles of Filaretova L. and co-authors. We will discuss in our articles how an endocrinological approach to gastroenterological field can advance our understanding of the HPA axis role in regulation of gastric mucosal integrity and uncover new findings. According to these findings activation of the HPA system is gastroprotective component of the brain-gut axis in stress but not ulcerogenic one as it was generally accepted. Corticotropin-releasing factor (CRF) and glucocorticoids are important natural players provided gastroprotection. The results suggest that an initial action of endogenous glucocorticoids, including stress- and CRF-produced ones, as well as exogenous glucocorticoids, even used at pharmacological doses, is physiological gastroprotective. Prolongation of the hormonal action may lead to the transformation of gastroprotective hormonal effect to proulcerogenic one.ConclusionThe findings of this review demonstrate that corticotropin-releasing factor and glucocorticoids contribute to the realization of the brain-gut interactions and that activation of the HPA system is gastroprotective component of this interaction in stress.

Effective long term adaptation and metabolic state regulation of ski-racers

Purpose: to scientifically substantiate effective mechanisms of organism’s bio-chemical adaptation of ski-racers in competition period with the help of lipid peroxidation indicators, oxidative modification of proteins and activity of hypothalamus pituitary adrenocortical system. Material: in the research 14 sportsmen of 18-25 years’ age (combined team of university) with different level of sportsmanship participated. Assessment of free radical oxidation, anti-oxidant system, cortisol level was fulfilled with the help of indicators’ quantitative analysis by bio-chemical methods applied to blood serum samples. Results: it was found that in the basis of bio-chemical changes under intensive physical loads is increase of catabolic processes’ speed. Change of organism’s metabolic orientation of ski racers at optimal level results in working muscles’ energy supply improvement, increase of energy systems’ power and sports efficiency. Conclusions: Application of interval trainings at stages of preparation to special significant competitions results in expected adaptation and increase of sports efficiency. We also showed their effective role in ensuring long term reactions, conditioning high sports efficiency.

Prenatal Maternal Stress Predicts Methylation of Genes Regulating the Hypothalamic-Pituitary-Adrenocortical System in Mothers and Newborns in the Democratic Republic of Congo.

Exposure to stress early in life permanently shapes activity of the hypothalamic-pituitary-adrenocortical (HPA) axis and the brain. Prenatally, glucocorticoids pass through the placenta to the fetus with postnatal impacts on brain development, birth weight (BW), and HPA axis functioning. Little is known about the biological mechanisms by which prenatal stress affects postnatal functioning. This study addresses this gap by examining the effect of chronic stress and traumatic war-related stress on epigenetic changes in four key genes regulating the HPA axis in neonatal cord blood, placenta, and maternal blood: CRH, CRHBP, NR3C1, and FKBP5. Participants were 24 mother-newborn dyads in the conflict-ridden region of the eastern Democratic Republic of Congo. BW data were collected at delivery and maternal interviews were conducted to assess culturally relevant chronic and war-related stressors. Chronic stress and war trauma had widespread effects on HPA axis gene methylation, with significant effects observed at transcription factor binding (TFB) sites in all target genes tested. Some changes in methylation were unique to chronic or war stress, whereas others were observed across both stressor types. Moreover, stress exposures impacted maternal and fetal tissues differently, supporting theoretical models that stress impacts vary according to life phase. Methylation in several NR3C1 and CRH CpG sites, all located at TFB sites, was associated with BW. These findings suggest that prenatal stress exposure impacts development via epigenetic changes in HPA axis genes.

P.1.e.017 A decrease in phosphorylation of CREB may explain delayed place learning and attenuated long-term potentiation in adult-onset hyperthyroidism

The hippocampal mineralocorticoid receptor (MR) is critical for the regulation of the basal activity of the hypothalamus–pituitary–adrenocortical (HPA) system. It has been hypothesized that reduced capacity of the hippocampal MR is involved in the HPA-system dysregulation found in depression and aging. We applied the combined dexamethasone suppression/corticotropin releasing hormone stimulation (DEX/CRH) test to six healthy young females both before and after 12 days of treatment with the MR antagonist spironolactone to assess HPA regulation. Treatment with spironolactone caused a significant increase in post-dexamethasone cortisol concentrations (75.1±56.7 vs. 36.6±24.6 nmol/l, p<0.05). Furthermore, we observed a significant rise in peak cortisol concentration after additional human CRH (hCRH) application (223.6±139.1 vs. 126.7±73.3 nmol/l, p<0.02). There was no change in ACTH plasma concentrations. We thus conclude that (1) the MR antagonist spironolactone affects HPA system regulation as reflected in the DEX/CRH test and (2) these findings are in accordance with the assumption that MR dysfunction may underlie HPA-system dysfunction in depression and/or aging.

Chronic Psychological Stress as a Risk Factor of Osteoporosis.

Osteoporosis, the most common metabolic skeletal disease, is characterized by decreased bone mass and deteriorated bone quality, leading to increased fracture risk. With the aging of the population, osteoporotic fracture is an important public health issue. Organisms are constantly exposed to various stressful stimuli that affect physiological processes. Recent studies showed that chronic psychological stress is a risk factor for osteoporosis by various signaling pathways. The purpose of this article is to review the recent progress of the association between chronic psychological stress and osteoporosis. Increasing evidence confirms the physiological importance of the central nervous system, especially the hypothalamus, in the regulation of bone metabolism. Both animal and human studies indicate that chronic psychological stress induces a decrease of bone mass and deterioration of bone quality by influencing the hypothalamic-pituitary-adrenocortical (HPA) axis, sympathetic nervous system, and other endocrine, immune factors. Active mastication, proven to be an effective stress-coping behavior, can attenuate stress-induced neuroendocrine responses and ameliorate stress-induced bone loss. Therefore, active mastication may represent a useful approach in preventing and/or treating chronic stress-associated osteoporosis. We also discuss several potential mechanisms involved in the interaction between chronic stress, mastication and osteoporosis. Chronic stress activates the HPA axis and sympathetic nervous system, suppresses the secretion of gonadal hormone and growth hormone, and increases inflammatory cytokines, eventually leading to bone loss by inhibiting bone formation and stimulating bone resorption.

REM sleep alteration and depression

Alterations in sleep patterns are often recognized as a premorbid symptom accompanied by affective disorders, particularly by major depression. However, the mechanism is rather complex, and differentiating its causalities from those of depression undergoes hardships. Indeed, depression is a complex disease. It has been clearly demonstrated that depressed patients display very characteristic changes in sleep architecture. Previous animal studies also demonstrated that several depression models, which had targeted elevated hypothalamic-pituitary-adrenocortical (HPA) axis, showed increased rapid eye movement (REM) sleep while insomniac sleep phenotype did not evidently appear. However, all stress hor- mones seem to be elevated in those models. Therefore, it has been difficult to determine which particular hormone in the HPA axis is primarily responsible for altered sleep in depression. In recent years, we have widely analyzed sleep charac- teristics of conditional transgenic mouse lines focusing on corticotropin-releasing hormone (CRH), the initial mediator of the HPA system, in which the levels of peripheral stress hormones are normal. Conditional CRH-overexpressing (COE) mice, especially those overexpress CRH limitedly within the forebrain including limbic structures (CRH-COE-Cam), dis- play enhanced REM sleep. Further, the higher occurrence of REM sleep in CRH-COE-Cam mice could be due to their hyper-cholinergic activity. REM sleep disinhibition observed in depressed patients similarly appears in animals which are genetically stress-vulnerable strain or chronically stressed, possibly due to enhanced action of limbic CRH. Indeed, REM sleep is a fragile vigilance state and closely connected with emotional control. Thus, depressive episodes may affect REM sleep earlier than nonREM sleep, and such altered REM sleep can be a state marker of depression.

REM sleep alteration and depression.

Alterations in sleep patterns are often recognized as a premorbid symptom accompanied by affective disorders, particularly by major depression. However, the mechanism is rather complex, and differentiating its causalities from those of depression undergoes hardships. Indeed, depression is a complex disease. It has been clearly demonstrated that depressed patients display very characteristic changes in sleep architecture. Previous animal studies also demonstrated that several depression models, which had targeted elevated hypothalamic-pituitary-adrenocortical (HPA) axis, showed increased rapid eye movement (REM) sleep while insomniac sleep phenotype did not evidently appear. However, all stress hormones seem to be elevated in those models. Therefore, it has been difficult to determine which particular hormone in the HPA axis is primarily responsible for altered sleep in depression. In recent years, we have widely analyzed sleep characteristics of conditional transgenic mouse lines focusing on corticotropin-releasing hormone (CRH), the initial mediator of the HPA system, in which the levels of peripheral stress hormones are normal. Conditional CRH-overexpressing (COE) mice, especially those overexpress CRH limitedly within the forebrain including limbic structures (CRH-COE-Cam), dis- play enhanced REM sleep. Further, the higher occurrence of REM sleep in CRH-COE-Cam mice could be due to their hyper-cholinergic activity. REM sleep disinhibition observed in depressed patients similarly appears in animals which are genetically stress-vulnerable strain or chronically stressed, possibly due to enhanced action of limbic CRH. Indeed, REM sleep is a fragile vigilance state and closely connected with emotional control. Thus, depressive episodes may affect REM sleep earlier than nonREM sleep, and such altered REM sleep can be a state marker of depression.

Association between the Daytime Plasma Cortisol Level and Depression Component of Hamilton Depression Rating Scale in Korean Depression Clinic Outpatients

Objectives ZZThere is evidence that Hypothalamic-Pituitary-Adrenocortical (HPA) system dysregulation plays a role in the pathophysiology of depression. However which psychiatric symptoms are related to HPA system dysregulation has not been studied well. The primary aim of this study was to investiga...

Effects of escitalopram/quetiapine combination therapy versus escitalopram monotherapy on hypothalamic–pituitary–adrenal-axis activity in relation to antidepressant effectiveness

The hypothalamic–pituitary–adrenocortical (HPA) system is believed to play an important role in the pathophysiology of major depressive disorder. In this context, the atypical antipsychotic quetiapine (QUE) has been shown to inhibit HPA system activity in healthy subjects. In this study we investigated whether the putative inhibitory effects of QUE on HPA system activity may contribute to its antidepressant efficacy. We analyzed the effects of QUE as an augmentation to the selective serotonin reuptake inhibitor (SSRI) escitalopram (ESC) on HPA system activity in comparison to a monotherapy with ESC in relation to the antidepressant effectiveness. HPA axis activity (cortisol and ACTH) was measured by means of the dexamethasone/corticotropin-releasing hormone (DEX/CRH) test which was performed before (week 0) and during (week 1, week 5) antidepressant psychopharmacotherapy. The combination therapy, but not the ESC monotherapy showed significantly inhibiting effects on HPA system activity leading to stepwise down-regulation. ACTH concentrations were reduced in the ESC/QUE group during five weeks of treatment. The inhibitory effect of QUE maybe involved in its antidepressant effects as an augmentation strategy.

Future Directions in the Study of Social Relationships as Regulators of the HPA Axis Across Development

Many promising findings support the notion that social relationships can dampen hypothalamic-pituitary-adrenocortical (HPA) axis stress responses and protect individuals from maladaptive psychological and physical disease states. Despite the public health relevance of this topic, little is known about developmental changes in the social regulation of the HPA system, with most prior research having focused on early childhood and adulthood. This gap is particularly striking with regards to adolescence, an age period when it seems likely that reliance on parents as sources of stress-buffering decreases, even as the security of friends and relationship partners as stress buffers may not yet be certain. Furthermore, we speculate that early life stress or abnormal social experiences may impact the propensity to draw mental and physical health benefits from social relationships, but more empirical support for these ideas is needed. Last, research linking social support to cumulative life stress has mostly relied on self-report measures of stress, making it difficult to show that social support impacts the type of chronic stress exposure that is associated with increased allostatic load or “wear and tear” on the body and on psychological functioning. Recent advancements in methodology (e.g., assessing hair cortisol levels) as well as composite measures of allostatic load using biomarkers that capture the activity of multiple neuroendocrine, cardiovascular, immune, and metabolic systems will allow us to ask new questions about the extent to which social relationships can impact cumulative life stress and health.

Early Adverse Care, Stress Neurobiology, and Prevention Science: Lessons Learned

There is growing evidence that some of the difficulties observed among children who have experienced early adverse care (e.g., children internationally adopted from institutional care and maltreated children in foster care) involve experience-induced alterations in stress-responsive neurobiological systems, including the hypothalamic-pituitary-adrenocortical (HPA) system. Thus, incorporating stress neurobiology into prevention research could aid in identifying the children most in need of preventive intervention services, elucidating the mechanisms of change in effective interventions, and providing insight into the differential responses of children to effective interventions. However, integrating stress neurobiology and prevention research is challenging. In this paper, the results of studies examining HPA system activity in children who have experienced early adverse care are reviewed, the implications of these results for prevention research are discussed, and critical steps for successfully incorporating stress neurobiology into prevention research are identified.

Stress, the HPA axis, and nonhuman primate well-being: A review

Numerous stressors are routinely encountered by wild-living primates (e.g., food scarcity, predation, aggressive interactions, and parasitism). Although many of these stressors are eliminated in laboratory environments, other stressors may be present in that access to space and social partners is often restricted. Stress affects many physiological systems including the hypothalamic–pituitary–adrenocortical (HPA) axis, which is the focus of this review. The glucocorticoid, cortisol, is the ultimate output of this system in nonhuman primates, and levels of this hormone are used as an index of stress. Researchers can measure cortisol from several sampling matrices that include blood, saliva, urine, faeces, and hair. A comparison of the advantages and disadvantages of each sampling matrix is provided to aid researchers in selecting an optimal strategy for their research. Stress and its relationship to welfare have been examined in nonhuman primates using two complimentary approaches: comparing baseline cortisol levels under different conditions, or determining the reactivity of the system through exposure to a stressor. Much of this work is focused on colony management practices and developmental models of abnormal behaviour. Certain colony practices are known to increase stress at least temporarily. Both blood sampling and relocation are examples of this effect, and efforts have been made to reduce some of the more stressful aspects of these procedures. In contrast, other colony management practices such as social housing and environmental enrichment are hypothesized to reduce stress. Testing this hypothesis by comparing baseline cortisol levels has not proved useful, probably due to “floor” effects; however, social buffering studies have shown the powerful role of social housing in mitigating reactions of nonhuman primates to stressful events. Models of abnormal behaviour come from two sources: experimentally induced alterations in early experience (e.g., nursery rearing), and the spontaneous development of behavioural pathology (e.g., self-injurious behaviour). Investigators have often assumed that abnormal behaviour is a marker for stress and thus such monkeys are predicted to have higher cortisol levels than controls. However, an emerging finding is that monkeys with abnormal behaviour are more likely to show a pattern of lowered cortisol concentrations which may reflect either an altered set point or a blunting of the stress response system. These findings parallel human clinical studies demonstrating that neuropsychiatric disorders may be associated with either increased or decreased activity of the HPA system, depending on the aetiology and manifestation of the disorder and their potential influence in provoking allostatic shifts in system functioning.

Adoption as an intervention for institutionally reared children: HPA functioning and developmental status

Institutional care, particularly when experienced early in life, is associated with delays in social and emotional development that often persist years after adoption. It has been hypothesized that compromise of the hypothalamic–pituitary–adrenocortical (HPA) axis due to adverse condition in institutions is a mediator of later emotional and behavioral problems. The first goal of our project was to investigate whether improvements in the social and emotional environment are associated with changes in HPA axis function. The second goal was to explore whether HPA alterations related to early social adversity were associated with more compromised general development and social and emotional functioning post adoption. Children adopted from Eastern European orphanages (N=76, mean age was 17 months, SD=5) were followed as part of an ongoing longitudinal study. Data, including diurnal cortisol patterns, were collected at two time points: baseline (within one month of adoption) and follow-up (six months later). Cortisol values were averaged over two days of saliva sampling after wake-up and before bedtime. We found that morning cortisol values increased between the baseline assessment (M=0.27μg/dl, SD=0.13) and follow-up (M=0.33μg/dl, SD=0.20), t(76)=−2.1, p<0.05. HPA functioning was not associated with general developmental level at either the initial or six months post-adoption assessments. However, dysregulation of the HPA axis (i.e., flatter diurnal pattern) at follow-up was associated with more behavioral and emotional problems. Overall, these results suggest that investigating specific physiological mechanisms is important in identifying children at risk for persistent social and emotional problems and in understanding the long-term consequences of early adversity. Future work should investigate whether disturbance in the HPA system is a heightened risk for long-term negative developmental outcomes.