Down-regulating the stress axis: Living in the present while preparing for the future

The measurement of glucocorticoid (GC) hormones provides us with a window into the stress physiology of vertebrates and the adaptative responses they use to cope with predictable and unpredictable changes in the environment. Baseline GCs inform us about the metabolic demands they are subject to at that point in their yearly life-history stage, whereas GC changes (often increases) in response to acute challenges inform us on their capacity to cope with more immediate environmental challenges. However, baseline GC levels and the kinetics of GC responses to acute stressors can vary substantially among and within species, depending on individual characteristics (age, sex, condition, life-history stage). In addition, a thorough understanding of the stress status of an animal requires moving beyond the measurement of GCs alone by focusing on downstream measures of metabolic activation, such as oxidative stress. Here, we evaluated the changes in blood cortisol and oxidative stress markers in wild adult Columbian ground squirrels (Urocitellus columbianus), following a 30-min capture-handling stress performed in mid-late June. Measurements were taken when males were post-reproductive and preparing for hibernation and adult females were weaning litters. We found three key results. First, the time-course of GC increase was markedly slower (by an order of magnitude) than what is currently reported in the literature for most species of mammals, birds and reptiles. Second, there were marked differences in the male and female response, linked to differences in life-history stage: females close to weaning had abolished GC responses, whereas post-reproductive males did not. Third, there were mild to moderate increases in oxidative damage and decreases in oxidative defenses in response to our short-term challenge, consistent with the idea that short-term acute metabolic activation may carry physiological costs. However, these changes were not correlated to the changes in GCs, a novel result suggesting a disconnect between the hormonal stress response and oxidative damage.

Higher prenatal anxiety predicts lower neonatal hair cortisol

BACKGROUND

Prenatal glucocorticoids are one of the most widely proposed prenatal programming mechanisms, yet few studies exist that measure fetal cortisol via neonatal hair. Neonatal hair provides a window into the fetal experience and represents cortisol accumulation in the third trimester of pregnancy. In the current study, we test the links between two types of anxiety over the course of gestation (pregnancy-related anxiety and general anxiety) with neonatal hair cortisol.

METHOD

Pregnant individuals (N = 107) and their neonates (59.8% female) participated in the current study. Prenatal pregnancy-related anxiety and general anxiety were measured using the Pregnancy Related Anxiety Scale (PRAS) and the State-Trait Anxiety Inventory (STAI), in each trimester of pregnancy. Hierarchical linear modeling was used to model the intercept and slope of each type of anxiety over gestation. Neonatal hair samples were collected shortly after birth (Median days = 1.17, IQR = 0.75-2.00).

RESULTS

Both higher pregnancy-related anxiety and general anxiety at the beginning of pregnancy and a flatter decline of pregnancy-related anxiety over gestation were associated with lower neonatal hair cortisol. After inclusion of gestational age at birth and parity as covariates, pregnancy-related anxiety (intercept: β = -0.614, p =.012; slope: β = -0.681, p =.006), but not general anxiety (intercept: β = -0.389, p =.114; slope: β = -0.302, p =.217) remained a significant predictor. Further, when both general and pregnancy-related anxiety were entered into the same model, only pregnancy-related anxiety (intercept and slope) were significant predictors of neonatal hair cortisol, indicating an association with pregnancy-related anxiety above and beyond general anxiety.

CONCLUSION

Cortisol plays a central role in maturation of fetal organ systems, and at the end of gestation, higher cortisol has beneficial effects such as promoting fetal lung maturation. Further, lower maternal cortisol is linked to less optimal cognitive development and altered brain development. As maternal higher anxiety in early pregnancy and a flatter decrease over time are both associated with lower neonatal hair cortisol, maternal pregnancy-related anxiety could be a target of future intervention efforts.

Impact of social isolation on corticosterone release and recovery after stroke in aged rats: A behavioral and biochemical analysis

Social isolation (SI) after stroke reduces recovery. The aim of this study was to evaluate the effects of SI on corticosterone release and recovery after stroke in aged rats. A total of 64 male Wistar rats (aged 24 months) were used in the present study. All rats were housed in pairs for two weeks. After two weeks, rats were randomly assigned to one of four groups: (1) rats underwent sham surgery and kept socially isolated (control/social isolated (CO/SI) group); (2) rats underwent sham surgery and kept pair housed (control/pair housed (CO/PH) group); (3) rats underwent middle cerebral artery occlusion (MCAO) surgery and kept socially isolated (stroke/isolated (ST/SI) group); (4) rats underwent MCAO surgery and kept pair housed (stroke/pair housed (ST/PH)) group. Behaviors were assessed using the adhesive removal test, rotarod test and social interaction test at 1st, 7th, 14th and 21st days after stroke. Serum biochemical analysis was also performed on the behavioral testing days. Results showed THAT serum corticosterone and MDA levels in CO/PH group were significantly lower than CO/SI group. Serum BDNF levels in CO/PH group was significantly higher than CO/SI group. Serum corticosterone and MDA levels in ST/PH group were lower than ST/SI group. In ST/PH group, serum Total antioxidant capacity (TAC) and BDNF levels were significantly higher than ST/SI group. Biochemical analysis of certain regions of the brain (hippocampus, striatum and cerebral cortex) was performed on 21st day after stroke. In the hippocampus of CO/PH group, BDNF and TAC levels were significantly higher than CO/SI group. The hippocampal MDA level of CO/PH group were significantly lower than CO/SI group. BDNF and TAC levels in the hippocampus, striatum and cerebral cortex of ST/PH group were significantly higher and MDA level was significantly lower as compared with ST/SI group. Both ischemic groups showed sensorimotor recovery over a 21-day period, but recovery of ST/PH group was significantly greater than ST/SI group. Total social interaction time in ST/PH group was significantly longer than ST/SI group. Based on the results of this study, social interaction after stroke enhances histologic and sensorimotor recovery through reduction of HPA activity and corticosterone release, leading to increased TAC and BDNF levels.

Decision-making under stress: A psychological and neurobiological integrative model

Understanding the impact of stress on cognitive processes, particularly decision-making, is crucial as it underpins behaviors essential for survival. However, research in this domain has yielded disparate results, with inconsistencies evident across stress-induction paradigms and drug administration protocols designed to investigate specific stress pathways or neuromodulators. Building upon empirical studies, this research identifies a multifaceted matrix of variables contributing to the divergent findings. This matrix encompasses factors such as the temporal proximity between stressors and decision tasks, the nature of stressors and decision contexts, individual characteristics including psychobiological profiles and affective states at the time of decision-making and even cultural influences. In response to these complexities, we propose a comprehensive model that integrates these relevant factors and their intricate interplay to elucidate the mechanisms governing decision-making during stressful events. By synthesizing these insights, our model not only refines existing paradigms but also provides a framework for future study designs, offering avenues for theoretical advancements and translational developments in the field of stress's impact on cognitive functions. This research contributes to a deeper understanding of the nuanced relationship between stress and decision-making, ultimately advancing our knowledge of cognitive processes under challenging conditions.

Hypothalamic-pituitary-adrenal axis hyperactivity is normalized after successful intermittent theta-burst stimulation in resistant depressed patients

The present pilot study assessed the effects of multi-session intermittent theta-burst stimulation (iTBS) applied to the left dorsolateral prefrontal cortex in 17 treatment resistant depressed inpatients (TRDs) showing cortisol non-suppression to the overnight dexamethasone suppression test (DST) at baseline (i.e., maximum post-DST cortisol [CORmax] level > 130 nmol/L). After 20 iTBS sessions, the DST was repeated in all TRDs. At baseline, post-DST CORmax levels were higher in TRDs compared to healthy control subjects (HCs; n = 17) (p < 0.0001). After 20 iTBS sessions, post-DST CORmax levels decreased from baseline (p < 0.03) and were comparable to HCs. Decreases in post-DST CORmax levels were related to decreases in 17-item Hamilton Depression Rating Scale (HAMD-17) scores (ρ = 0.53; p < 0.03). At endpoint, 10 TRDs showed DST normalization (among them 7 were responders [i.e., HAMD-17 total score > 50% decrease from baseline]), and 7 did not normalize their DST (among them 6 were non-responders) (p < 0.05). Our results suggest that successful iTBS treatment may restore normal glucocorticoid receptor feedback inhibition at the pituitary level.

Associations of schizophrenia with the activities of the HPA and HPG axes and their interactions characterized by hair-based biomarkers

BACKGROUND

Past studies on schizophrenia (SCZ) and the stress-sensitive neuroendocrine systems have mostly focused on a single system and traditionally utilized acute biomarkers (e.g., biomarkers from blood, urine and saliva) that poorly match the chronic course of schizophrenia in time span. Using eight biomarkers in hair, this study aimed to explore the functional characteristics of SCZ patients in the hypothalamic-pituitary-adrenocortical (HPA) and hypothalamic-pituitary-gonadal (HPG) axes and the interaction between the two axes.

METHODS

Hair samples were taken from 137 SCZ patients and 73 controls. The SCZ patients were diagnosed by their attending physician according to the Diagnostic and Statistical Manual of Mental Disorders IV and were clinically stable after treatment. Gender, age, BMI, frequency of hair washing, marital status, education level, family history of mental illness and clozapine dosage were concurrently collected as covariates. The 10-item perceived stress scale (PSS-10) and the social readjustment rating scale were used to assess chronic stress status in SCZ patients. Eight hair biomarkers, cortisol, cortisone, dehydroepiandrosterone (DHEA), testosterone, progesterone, cortisol/cortisone, cortisol/DHEA and cortisol/testosterone, were measured by high performance liquid chromatography tandem mass spectrometer. Among them, cortisol, cortisone, DHEA and cortisol/DHEA reflected the functional activity of the HPA axis, and testosterone and progesterone reflected the functional activity of the HPG axis, and cortisol/cortisone reflected the activity of 11β-hydroxysteroid dehydrogenase types 2 (11β-HSD 2), and cortisol/testosterone reflected the HPA-HPG interaction.

RESULTS

SCZ patients showed significantly higher cortisone and cortisol/testosterone than controls (p<0.001, η²p=0.180 and p=0.015, η²p=0.031), lower testosterone (p=0.009, η²p=0.034), progesterone (p<0.001, η²p=0.069) and cortisol/cortisone (p=0.001, η²p=0.054). There were significant intergroup differences in male and female progesterone (p=0.003, η²p=0.088 and p=0.030, η²p=0.049) and female testosterone (p=0.028, η²p=0.051). In SCZ patients, cortisol, cortisol/cortisone, cortisol/DHEA and cortisol/testosterone were positively associated with PSS-10 score (ps<0.05, 0.212

CONCLUSION

The function of the HPA and HPG axes, the activity of 11β-HSD 2 and the HPA-HPG interaction were abnormal in SCZ patients. The abnormality of neuroendocrine systems was associated with chronic stress status in SCZ patients. This study provided evidence for abnormalities in the neuroendocrine systems in SCZ patients.

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Key Words

• 11β-HSD 2
• HPA axis
• HPG axis
• Hair biomarkers
• Schizophrenia

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MESH Headings

• Humans
• Female
• Male
• Hypothalamo-Hypophyseal System/metabolism
• Schizophrenia/metabolism
• Pituitary-Adrenal System/metabolism
• Pituitary-Adrenal System/physiopathology
• Hair/chemistry
• Hair/metabolism
• Biomarkers/metabolism
• Adult
• Hydrocortisone/metabolism
• Hydrocortisone/analysis
• Cortisone/metabolism
• Cortisone/analysis
• Testosterone/metabolism
• Testosterone/analysis
• Dehydroepiandrosterone/metabolism
• Dehydroepiandrosterone/analysis
• Stress, Psychological/metabolism
• Middle Aged
• Progesterone/metabolism
• Progesterone/analysis
• Case-Control Studies

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The cortisol/DHEA ratio mediates the association between early life stress and externalizing problems in adolescent boys

BACKGROUND

Despite evidence that early life stress (ELS) can influence the functioning of the hypothalamic-pituitary-adrenal (HPA) axis and increase maladaptive behaviors in adolescence, less attention has been paid to the role of the coordinated effects of the two primary adrenal hormones, cortisol and dehydroepiandrosterone (DHEA), in these associations.

METHODS

138 typically developing adolescents (76 females) reported the stressful events experienced during childhood and early adolescence across 30 domains. Two years later we assessed levels of externalizing problems and obtained salivary levels of cortisol and DHEA. Using causal moderated mediation analyses, we examined whether the ratio of cortisol to DHEA (CD ratio) mediates the association between ELS and subsequent externalizing problems.

RESULTS

We found that ELS is associated with both a lower CD ratio and more externalizing problems. Importantly, a lower CD ratio mediated the association between ELS and externalizing problems in boys.

CONCLUSIONS

An imbalance in adrenal hormones may be a mechanism through which ELS leads to an increase in externalizing problems in adolescent boys. These findings underscore the utility of using the CD ratio to index HPA-axis functioning.

Prenatal co-exposure to diisodecyl phthalate and ozone contribute to depressive behavior in offspring mice through oxidative stress and TWIST1 participation

Exposure to diisodecyl phthalate (DIDP) during early pregnancy may be a risk factor for depressive behavior in offspring. While ozone (O3) exposure also raises the probability of depressive behavior during the preceding DIDP-induced process. In the present study, we investigated the effects of prenatal exposure to DIDP and O3 on the development of depressive-like behavior in offspring mice. The study found that prenatal exposure to both DIDP and O3 significantly increased depressive-like behavior in the offspring mice compared to either DIDP or O3 alone. Prenatal exposure to DIDP and O3 obviously increased the levels of corticotropin-releasing hormone (CRH), adrenocorticotropic hormone (ACTH) and cortisol, and decreased the levels of brain-derived neurotrophic factor (BDNF), 5-hydroxytryptamine (5-HT), dopamine (DA) and norepinephrine (NE) in the brain tissues of offspring mice. Transcriptome analysis further revealed significant alterations in genes related to oxidative stress and TWIST1 (a helix-loop-helix transcription factor) in response to the combined exposure to DIDP and O3. HPA axis activation, dysregulation of neurodevelopmental factors, oxidative stress and TWIST1 involvement, collectively contributed to the development of depression-like behaviors in offspring mice following prenatal exposure to DIDP and O3. Moreover, the study also verified the potential role of oxidative stress using vitamin E as an antioxidant. The findings provide valuable evidence for the relationship between co-exposure to DIDP and O3 and depression, highlighting the importance of considering the combined effects of multiple environmental pollutants in assessing their impact on mental health outcomes.

Effects of paradoxical sleep deprivation on oxidative parameters in the serum and brain of mice submitted to the animal model of hyperglycemia

The present study aimed to investigate the effects of paradoxical sleep deprivation (PSD) on behavioral and oxidative stress parameters in the brain and serum of mice submitted to the animal model of hyperglycemia induced by alloxan, mimicking the main symptom of diabetes mellitus (DM). Adults C57BL/6 male and female mice received an injection of alloxan, and ten days later, the animals were submitted to the PSD for 36 h. The animals' behavioral parameters were evaluated in the open-field test. Oxidative stress parameters [Diacetyldichlorofluorescein (DCF), Thiobarbituric acid reactive substances (TBARS), Superoxide dismutase (SOD), and Glutathione] were assessed in the frontal cortex, hippocampus, striatum, and serum. The PSD increased the male and female mice locomotion, but the alloxan's pre-administration prevented the PSD-induced hyperactivity. In addition, the male mice receiving alloxan and submitted to the PSD had elevated latency time in the first quadrant and the number of fecal boli, demonstrating increased anxiety-like behavior. The HPA-axis was hyperactivating in male and female mice pre-administered alloxan and/or PSD-submitted animals. The oxidative stress parameters were also increased in the serum of the animals administered alloxan and/or sleep-deprived mice. Despite alloxan or PSD leading to behavioral or biochemical alterations, the one did not potentiate the other in mice. However, more studies are necessary to identify the link between sleep and hyperglycemia.

Infant colic and HPA axis development across childhood

This study examines the long-term impact of infant colic on Hypothalamic-Pituitary-Adrenal (HPA) axis development and the moderating role of attachment security, in a low-risk Dutch sample of 193 children. We assessed infant colic at 6 weeks, circadian cortisol concentrations at ages 1, 2.5, 6, and 10 years, and attachment security at 1 year. Findings indicated that infant colic was associated with steeper diurnal cortisol slopes and slightly higher cortisol concentrations throughout childhood. Attachment security did not moderate these associations. This is the first study to reveal a link between infant colic and the development of the HPA axis in healthy children beyond infancy. These findings have important implications for understanding early risk and protective factors in the stress system's development.

The impact of devaluing Women of Color: stress, reproduction, and justice

This commentary is in response to the Call for Papers put forth by the Critical Midwifery Studies Collective (June 2022). We argue that due to a long and ongoing history of gendered racism, Women of Color are devalued in U.S. society. Devaluing Women of Color leads maternal healthcare practitioners to miss and even dismiss distress in Women of Color. The result is systematic underdiagnosis, undertreatment, and the delivery of poorer care to Women of Color, which negatively affects reproductive outcomes generally and birth outcomes specifically. These compounding effects exacerbate distress in Women of Color leading to greater distress. Stress physiology is ancient and intricately interwoven with healthy pregnancy physiology, and this relationship is a highly conserved reproductive strategy. Thus, where there is disproportionate or excess stress (distress), unsurprisingly, there are disproportionate and excess rates of poorer reproductive outcomes. Stress physiology and reproductive physiology collide with social injustices (i.e., racism, discrimination, and anti-Blackness), resulting in pernicious racialized maternal health disparities. Accordingly, the interplay between stress and reproduction is a key social justice issue and an important site for theoretical inquiry and birth equity efforts. Fortunately, both stress physiology and pregnancy physiology are highly plastic-responsive to the benefits of increased social support and respectful maternity care. Justice means valuing Women of Color and valuing their right to have a healthy, respected, and safe life.

Androgen regulation of behavioral stress responses and the hypothalamic-pituitary-adrenal axis

Testosterone is a powerful steroid hormone that can impact the brain and behavior in various ways, including regulating behavioral and neuroendocrine (hypothalamic-pituitary-adrenal (HPA) axis) stress responses. Early in life androgens can act to alter development of brain regions associated with stress regulation, which ultimately impacts the display of stress responses later in life. Adult circulating androgens can also influence the expression of distinct genes and proteins that regulate stress responses. These changes in the brain are hypothesized to underlie the potent effects of androgens in regulating behaviors related to stress and stress-induced activation of the HPA axis. Androgens can induce alterations in these functions through direct binding to the androgen receptor (AR) or following conversion to estrogens and subsequent binding to estrogen receptors including estrogen receptor alpha (ERα), beta (ERβ), and G protein-coupled estrogen receptor 1 (GPER1). In this review, we focus on the role of androgens in regulating behavioral and neuroendocrine stress responses at different stages of the lifespan and the sex hormone receptors involved in regulating these effects. We also review the specific brain regions and cell phenotypes upon which androgens are proposed to act to regulate stress responses with an emphasis on hypothalamic and extended amygdala subregions. This knowledge of androgen effects on these neural systems is critical for understanding how sex hormones regulate stress responses.

Early life conditions reduce similarity between reproductive partners in HPA axis response to stress

Social environments modulate endocrine function, yet it is unclear whether individuals can become like their social partners in how they physiologically respond to stressors. This social transmission of hypothalamic-pituitary-adrenal (HPA) axis reactivity could have long-term consequences for health and lifespan of individuals if their social partners react to stressors with an exaggerated HPA axis response. We tested whether glucocorticoid levels in response to stress of breeding partners changes after breeding depending on whether partners had similar or dissimilar postnatal conditions. We manipulated postnatal conditions by mimicking early life stress in zebra finch chicks (Taeniopygia guttata) via postnatal corticosterone exposure. When they reached adulthood, we created breeding pairs where the female and male had experienced either the same or different early life hormonal treatment (corticosterone or control). Before and after breeding, we obtained blood samples within 3 min and after 10 min or 30 min of restraint stress (baseline, cort10, cort30). We found that corticosterone levels of individuals in response to restraint were affected by their own and their partner's early life conditions, but did not change after breeding. However, across all pairs, partners became more similar in cort30 levels after breeding, although differences between partners in cort10 remained greater in pairs with a corticosterone-treated female. Thus, we show that HPA axis response to stressors in adulthood can be modulated by reproductive partners and that similarity between partners is reduced when females are postnatally exposed to elevated glucocorticoids.

Early life nutrient restriction affects hypothalamic-pituitary-interrenal axis gene expression in a diet type-specific manner

Stressful experiences in early life can alter phenotypic expression later in life. For instance, in vertebrates, early life nutrient restriction can modify later life activity of the hypothalamic-pituitary-adrenal/interrenal axis (the HPI in amphibians), including the up- and downstream regulatory components of glucocorticoid signaling. Early life nutrient restriction can also influence later life behavior and metabolism (e.g., fat accumulation). Yet, less is known about whether nutrient stress-induced carryover effects on HPA/HPI axis regulation can vary across environmental contexts, such as the type of diet on which nutrient restriction occurs. Here, we experimentally address this question using the plains spadefoot toad (Spea bombifrons), whose larvae develop in ephemeral habitats that impose intense competition over access to two qualitatively distinct diet types: detritus and live shrimp prey. Consistent with diet type-specific carryover effects of early life nutrient restriction on later life HPI axis regulation, we found that temporary nutrient restriction at the larval stage reduced juvenile (i.e., post-metamorphic) brain gene expression of an upstream glucocorticoid regulator (corticotropin-releasing hormone) and two downstream regulators (glucocorticoid and mineralocorticoid receptors) only on the shrimp diet. These patterns are consistent with known diet type-specific effects of larval nutrient restriction on juvenile corticosterone and behavior. Additionally, larval nutrient restriction increased juvenile body fat levels. Our study indicates that HPA/HPI axis regulatory responses to nutrient restriction can vary remarkably across diet types. Such diet type-specific regulation of the HPA/HPI axis might provide a basis for developmental or evolutionary decoupling of stress-induced carryover effects.

Stress Biomarkers Transferred Into the Female Reproductive Tract by Seminal Plasma Are Associated with ICSI Outcomes

This study aimed to determine whether male stress is related to seminal stress biomarkers and pregnancy achievement in women exposed to their partner's seminal plasma (SP) in the intracytoplasmic sperm injection (ICSI) cycle. In this pilot prospective study, 20 couples undergoing ICSI, as well as 5 fertile sperm donors and 10 saliva donors, were investigated. Women were exposed to their partner's SP via unprotected sexual intercourse during the ICSI cycle and intravaginal application on the day of ovum pick-up (Day-OPU). Semen samples were collected from male partners by masturbation on the Day-OPU. Saliva and serum samples were collected prior to masturbation. Body fluids were frozen at - 80 °C until assayed. Biomarkers of activity of the sympathetic adrenomedullary axis (salivary alpha-amylase and adrenaline), sympathetic neural axis (noradrenaline and dopamine), hypothalamic-pituitary-adrenal (HPA) system (cortisol), and immune system (C-reactive protein and interleukin (IL)-18) were estimated to examine their association with SP composition and clinical pregnancy achievement. The clinical pregnancy rate was 45.0%. In the unsuccessful ICSI group, blunted levels of salivary and serum cortisol were found compared to the successful ICSI group and the fertile sperm donors. With regard to seminal markers, decreased cortisol level and elevated noradrenaline, noradrenaline/cortisol ratio, and lL-18 levels were strongly associated with ICSI failure (areas under the ROC curves were, 0.813, 0.848, 0.899, and 0.828, respectively). These findings confirm that stress response systems activity affects SP composition, which in turn is associated with ICSI outcomes in women exposed to their partner's SP during an ICSI cycle.

Gonads under stress: A systematic review and meta-analysis on the effects of acute psychosocial stress on gonadal steroids secretion in humans

Animal research has shown that the hypothalamus-pituitary-gonadal (HPG) axis is inhibited by (chronic and/or severe) stress, which can lead to impaired fertility and reproductive functioning, presumably caused by the inhibition of gonadal steroid secretion and in interactions with glucocorticoids. However, what has not been clarified is how acute psychosocial stress modulates gonadal steroid secretion in humans. Here we summarize the experimental research on the acute effects of stress on the secretion of gonadal steroids in humans. A systematic literature search revealed 21 studies (with N=881 individuals) measuring testosterone, progesterone or estradiol in response to a standardized acute laboratory stressor in healthy humans. Both our literature review and quantitative meta-analysis suggest that in humans, acute stress stimulates rather than inhibits HPG axis activity, although there is a considerable heterogeneity in the reported methods and results. Increased gonadal steroids in response to acute stress contrasts with many animal studies reporting the opposite pattern, at least regarding severe and/or chronic stressors. We discuss methodological issues and challenges for future research and hope to stimulate experimental studies within this area. A better understanding of these mechanisms is needed, and may have important implications for health and disease, as well as the modulation of various behaviors by acute stressors.

Effects of the combination of chronic unpredictable stress and environmental enrichment on anxiety-like behavior assessed using the elevated plus maze in Swiss male mice: Hypothalamus-Pituitary-Adrenal Axis-mediated mechanisms

Environmental enrichment (EE) is a paradigm that offers the animal a plethora of stimuli, including physical, cognitive, sensory, and social enrichment. Exposure to EE can modulate both anxiety responses and plasma corticosterone. In this study, our objective was to explore how chronic unpredictable stress (CUS) impacts anxiety-related behaviors in male Swiss mice raised in EE conditions. Additionally, we investigated corticosterone and adrenocorticotropic hormone (ACTH) levels to assess the involvement of the hypothalamic-pituitary-adrenal (HPA) axis in mediating these responses. Mice were housed under either EE or standard housing conditions for 21 days. Afterward, they were exposed to 11 days of CUS while still reared in their distinct housing conditions, with half of the mice receiving daily pretreatment with the vehicle and the other half receiving daily metyrapone (MET) injections, an inhibitor of steroid synthesis, 30 mins before CUS exposure. Blood samples were obtained to assess plasma corticosterone and ACTH levels. The 11-day CUS protocol induced anxiety-like phenotype and elevated ACTH levels in EE mice. Chronic MET pretreatment prevented anxiety-like behavior in the EE-CUS groups, by mechanisms involving increased plasma corticosterone levels and decreased ACTH. These results suggest a role of the HPA axis in the mechanism underlying the anxiogenic phenotype induced by CUS in EE mice and shed light on the complex interplay between environmental factors, stress, and the HPA axis in anxiety regulation.

Hypothalamic protein profiling from mice subjected to social defeat stress

The Hypothalmic-Pituitary-Adrenal axis also known as the HPA axis is central to stress response. It also acts as the relay center between the body and the brain. We analysed hypothalamic proteome from mice subjected to chronic social defeat paradigm using iTRAQ based quantitative proteomics to identify changes associated with stress response. We identified greater than 2000 proteins after processing our samples analysed through Q-Exactive (Thermo) and Orbitrap Velos (Thermo) at 5% FDR. Analysis of data procured from the runs showed that the proteins whose levels were affected belonged primarily to mitochondrial and metabolic processes, translation, complement pathway among others. We also found increased levels of fibrinogen, myelin basic protein (MBP) and neurofilaments (NEFL, NEFM, NEFH) in the hypothalamus from socially defeated mice. Interestingly, research indicates that these proteins are upregulated in blood and CSF of subjects exposed to trauma and stress. Since hypothalamus secreted proteins can be found in blood and CSF, their utility as biomarkers in depression holds an impressive probability and should be validated in clinical samples.

Functional Gastrointestinal Symptoms in Children with Autism and ADHD: Profiles of Hair and Salivary Cortisol, Serum Leptin Concentrations and Externalizing/Internalizing Problems

BACKGROUND

Functional Gastrointestinal Disorders (FGIDs) present a higher prevalence in individuals with Neurodevelopmental Disorders (NDDs). The Stress System and the Gut-Brain axis (GBA) may mediate these relations. We aimed to assess the prevalence and profile of FGIDs in a clinical sample of children with Autism Spectrum Disorder (ASD) and Attention Deficit/Hyperactivity Disorder (ADHD) compared to typically developing children (TD) as well as to investigate possible relations between stress-related biomarkers and internalizing/externalizing problems in children with NDDS.

METHODS

In total, 120 children, aged between 4 and 12 years old, formed three groups (N = 40, each): ADHD, ASD and TD. Salivary cortisol, hair cortisol and serum leptin were measured.

RESULTS

The ASD group had more FGID problems than the TD group (p = 0.001). The ADHD and ASD groups had higher total internalizing/externalizing problems than the TD group (p < 0.0001, p < 0.0001, p = 0.005, respectively). Children with FGIDs showed more total, internalizing and externalizing problems compared to children without FGIDs (p < 0.0001, p < 0.0001, p = 0.041, respectively). The ADHD group showed lower AUCg values (p < 0.0001), while the hair cortisol was higher for the TD group (p < 0.0001).

CONCLUSION

In conclusion, children with NDDs had more FGID symptoms and present higher internalizing and externalizing problems. Children with ADHD and FGIDs had more internalizing problems compared to those without FGIDs. No differences in stress-related biomarkers were shown to differentiate children with NDDs with and without FGIDs. Future prospective studies including a greater number of children may elucidate the biological pathways linking these comorbidities.

Associations of diurnal cortisol parameters with cortisol stress reactivity and recovery: A systematic review and meta-analysis

Researchers commonly assess the functioning of the hypothalamic-pituitary-adrenal (HPA) axis by measuring natural fluctuations of its end product cortisol throughout the day or in response to a standardized stressor. Although it is conceivable that an individual releasing relatively more cortisol when confronted with a laboratory stressor does the same in everyday life, inconsistencies remain in the literature regarding associations between diurnal cortisol parameters and cortisol stress responses. Hence, the current meta-analysis aggregated findings of 12 studies to examine overall associations of diurnal cortisol parameters (including total output, diurnal slope, and cortisol awakening response [CAR]) with cortisol stress reactivity and recovery in the Trier Social Stress Test (TSST). There were no significant overall associations of total output, slope, or CAR with stress reactivity. Lower total diurnal cortisol output was significantly related to better stress recovery, whereas diurnal slope and CAR were unrelated to stress recovery. Moderation analyses revealed that associations between diurnal cortisol and cortisol stress responses were dependent on the computation method of cortisol parameters, questioning the convergence and validity of commonly employed measures of stress reactivity and recovery. Overall, it seems that we cannot predict characteristics of the diurnal cortisol rhythm from a one-time measure of stress reactivity in a standardized psychosocial laboratory paradigm.

Stress and diurnal cortisol among Latino/a college students: A multi-risk model approach

The transition to college is a time of increased opportunity and stress spanning multiple domains. Adolescents who encounter significant stress during this transition may be vulnerable to adverse outcomes due to a "wear and tear" of the hypothalamic pituitary adrenal (HPA) axis. Latino/a students may be particularly at-risk for heightened stress exposure due to experiences of both minority-specific and general life stress. Despite this, little is known regarding the cumulative impact of multiple stressors on Latino/a students' HPA axis functioning. The present study employed a "multi-risk model" approach to examine additive, common, and cumulative effects of multiple stress forms (general, academic, social, financial, bicultural, ethnic/racial discrimination) on diurnal cortisol in a sample of first-year Latino/a college students (N = 196; 64.4% female; Mage = 18.95). Results indicated that no stress forms were additively associated with the cortisol awakening response (CAR), but general stress was associated with a flatter diurnal cortisol slope (DCS) and bicultural stress was linked with a steeper DCS. A college stress latent factor was associated with a lower CAR, whereas a latent factor of discrimination was not associated with diurnal cortisol. Cumulative risk was linked with a lower CAR. Findings highlight the physiological correlates of various stressors experienced by Latino/a college students.

Tao-Hong-Si-Wu-Tang Improves the Depressive-like Behaviors in Mice Experiencing Perimenopausal Depression Through Modulating Activity of the Hypothalamic-Pituitary-Adrenal-Ovary Axis and Activating the BDNF-TrkB-CREB Signaling Pathway

Tao-Hong-Si-Wu-Tang (THSWT), a traditional Chinese herbal remedy, is commonly utilized for the treatment of female perimenopausal depression through regulating menstruation, but the mechanism remains unknown. In this study, ICR mice were randomly divided into six groups: low, medium, and high dose of THSWT (0.5, 1.5, and 4.5 g/kg), soy isoflavone (250 mg/kg), ovariectomy group, and control group. All mice, except the control group, had ovaries removed and were exposed to hypoxic stimulation for 28 days to establish a perimenopausal depression mice model. The mice, having unrestricted access to food and water, were administered THSWT treatment for a duration of 14 days. The Western blotting and Enzyme linked immunosorbent assay kits were used to determine protein and hormone levels, respectively. Experimental results showed that THSWT reduced the immobility time of mice from 150.8 s to 104.9 s in the tail suspension test, and it decreased the immobility time of mice from 165.7 s to 119.0 s in the forced swimming test, outperforming the results obtained with soy isoflavones. In addition, THSWT upregulated the protein expression of follicle-stimulating hormone receptor and downregulated the protein expression of corticotropin-releasing hormone-receptor 1 in the hippocampus. Compared with the oophorectomized group, treatment with THSWT decreased the levels of corticosterone and adrenocorticotropic hormone in serum by 173.7 and 23.4 ng/mL, respectively. These findings showed that THSWT could stimulate the perimenopausal nerve tissue and regulate the level of serum hormones in mice. THSWT exhibited promising potential as a viable alternative drug for hormone treatment of perimenopause in clinical use.

Intracerebroventricular injection of kisspeptin in male rats activates hypothalamo-pituitary-gonadal axis, but not hypothalamo-pituitary-adrenal axis

Kisspeptin is an important hormone involved in the stimulation of the hypothalamo-pituitary gonadal (HPG) axis. The HPG axis can be suppressed in certain conditions such as stress, which gives rise to the activation of the hypothalamo-pituitary-adrenal (HPA) axis. However, the physiological role of kisspeptin in the interaction of HPG and HPA axis is not fully understood yet. This study was conducted to investigate the possible effects of central kisspeptin injection on HPG axis as well as HPA axis activity. Adult male Wistar rats were randomly divided into seven groups as followed: sham (control), kisspeptin (50 pmol), P234 (1 nmol), kisspeptin + p234, kisspeptin + antalarmin (0.1 μg), kisspeptin + astressin 2B (1 μg), and kisspeptin + atosiban (300 ng/rat) (n = 10 each group). At the end of the experiments, the hypothalamus, pituitary, and serum samples of the rats were collected. There was no significant difference in corticotropic-releasing hormone immunoreactivity in the paraventricular nucleus of the hypothalamus, serum adrenocorticotropic hormone, and corticosterone levels among all groups. Moreover, no significant difference was detected in pituitary oxytocin level. Serum follicle-stimulating hormone and luteinizing hormone levels of the kisspeptin, kisspeptin + antalarmin, and kisspeptin + astressin 2B groups were significantly higher than the control group. Serum testosterone levels were significantly higher in the kisspeptin kisspeptin + antalarmin, kisspeptin + astressin 2B, and kisspeptin + atosiban groups compared to the control group. Our findings suggest that central kisspeptin injection causes activation in the HPG axis, but not the HPA axis in male rats.

The Yin and Yang of the oxytocin and stress systems: opposites, yet interdependent and intertwined determinants of lifelong health trajectories

During parturition and the immediate post-partum period there are two opposite, yet interdependent and intertwined systems that are highly active and play a role in determining lifelong health and behaviour in both the mother and her infant: the stress and the anti-stress (oxytocin) system. Before attempting to understand how the environment around birth determines long-term health trajectories, it is essential to understand how these two systems operate and how they interact. Here, we discuss together the hormonal and neuronal arms of both the hypothalamic-pituitary-adrenal (HPA) axis and the oxytocinergic systems and how they interact. Although the HPA axis and glucocorticoid stress axis are well studied, the role of oxytocin as an extremely powerful anti-stress hormone deserves more attention. It is clear that these anti-stress effects depend on oxytocinergic nerves emanating from the supraoptic nucleus (SON) and paraventricular nucleus (PVN), and project to multiple sites at which the stress system is regulated. These, include projections to corticotropin releasing hormone (CRH) neurons within the PVN, to the anterior pituitary, to areas involved in sympathetic and parasympathetic nervous control, to NA neurons in the locus coeruleus (LC), and to CRH neurons in the amygdala. In the context of the interaction between the HPA axis and the oxytocin system birth is a particularly interesting period as, for both the mother and the infant, both systems are very strongly activated within the same narrow time window. Data suggest that the HPA axis and the oxytocin system appear to interact in this early-life period, with effects lasting many years. If mother-child skin-to-skin contact occurs almost immediately postpartum, the effects of the anti-stress (oxytocin) system become more prominent, moderating lifelong health trajectories. There is clear evidence that HPA axis activity during this time is dependent on the balance between the HPA axis and the oxytocin system, the latter being reinforced by specific somatosensory inputs, and this has long-term consequences for stress reactivity.

5-HT1A Receptors on Dentate Gyrus Granule Cells Confer Stress Resilience

BACKGROUND

Hyperactivity of granule cells in the ventral dentate gyrus (vDG) promotes vulnerability to chronic stress. However, which receptors in the vDG could be targeted to inhibit this hyperactivity and confer stress resilience is not known. The serotonin 1A receptor (5-HT1AR) is a Gi protein-coupled inhibitory receptor that has been implicated in stress adaptation, anxiety, depression, and antidepressant responses. 5-HT1ARs are highly expressed in the DG, but their potential to promote stress resilience by regulating granule cell activity has never been examined.

METHODS

We exposed male and female mice expressing 5-HT1ARs only in DG granule cells to 10 days of chronic social defeat stress (CSDS) and treated them with the 5-HT1AR agonist 8-OH-DPAT every day 30 minutes before each defeat throughout the CSDS paradigm. We then used whole-cell current clamp recordings, immunohistochemistry for the immediate early gene cFos, corticosterone immunoassays, and behavioral testing to determine how activating 5-HT1ARs on granule cells affects DG activity, neuroendocrine stress responses, and avoidance behavior.

RESULTS

We found that activating 5-HT1ARs hyperpolarized DG granule cells and reduced cFos+ granule cells in the vDG following CSDS, indicating that 5-HT1AR activation rescued stress-induced vDG hyperactivity. Moreover, 5-HT1AR activation dampened corticosterone responses to CSDS and prevented the development of stress-induced avoidance in the social interaction test and in the open field test.

CONCLUSIONS

Our findings show that activating 5-HT1ARs on DG granule cells can prevent stress-induced neuronal hyperactivity of the vDG and confer resilience to chronic stress.