Hypothalamus-pituitary-adrenal hyperactivity in human aging is partially refractory to stimulation by mineralocorticoid receptor blockade

Associations between social behaviour and proinflammatory immune activation are modulated by age in a free-ranging primate population

The effect of the social environment on the proinflammatory immune response may mediate the relationship between social environment and fitness but remains understudied outside captive animals and human populations. Age can also influence both immune function and social behaviour, and hence may modulate their relationships. This study investigates the role of social interactions in driving the concentrations of two urinary markers of proinflammatory immune activation, neopterin and soluble urokinase plasminogen activator receptor (suPAR), in a free-ranging population of rhesus macaques, Macaca mulatta. We collected 854 urine samples from 172 adult monkeys and quantified how urinary suPAR and neopterin concentrations were related to affiliative behaviour and agonistic behaviour received over 60 days. In females, but not in males, higher rates of affiliative interactions were associated with lower neopterin concentrations, while conversely, experiencing more agonistic interactions was associated with higher neopterin concentrations. The association between affiliation and neopterin concentration was modulated by age, with older females experiencing a stronger negative association between affiliative behaviour and neopterin concentration. There were no associations between suPAR concentration and social environment for either sex. This study demonstrates that proinflammatory immune activity is a potential mechanism mediating the association between social environment and fitness under naturalistic conditions and that age can be an important modulator of the effect of social environment on the immune system.

Diagnosing and treating the elderly individual with hypopituitarism

Hypopituitarism in the elderly is an underestimated condition mainly due to the non-specific presentation that can be attributed to the effects of aging and the presence of comorbidities. Diagnosis and treatment of hypopituitarism often represent a challenging task and this is even more significant in the elderly. Diagnosis can be insidious due to the physiological changes occurring with aging that complicate the interpretation of hormonal investigations, and the need to avoid some provocative tests that carry higher risks of side effects in this population. Treatment of hypopituitarism has generally the goal to replace the hormonal deficiencies to restore a physiological balance as close as possible to that of healthy individuals but in the elderly this must be balanced with the risks of over-replacement and worsening of comorbidities. Moreover, the benefit of some hormonal replacement therapies in the elderly, including sex hormones and growth hormone, remains controversial.

Age, Resources, and Emotion Regulation Need in Daily-Life Emotional Contexts

OBJECTIVES

The Strengths and Vulnerabilities Integration model (Charles, 2010) suggests older adults experience difficulty regulating emotions with high-arousal negative stimuli due to decreases in resources. We investigate relationships among age, physical and cognitive resources, emotional experience, and perceived emotion regulation (ER) needs.

METHODS

Participants aged 25-85 (N = 290) completed assessments of cognitive ability and physical health. In an experience sampling procedure (6x per day for 10 days), participants reported their momentary emotion experience and perceived need to regulate their emotions.

RESULTS

Regardless of arousal level, negative emotion was associated with higher ER need and positive emotion was associated with lower ER need. This pro-hedonic orientation was stronger among older adults and individuals with more cognitive resources. In contrast to predictions, older adults in poor physical health who experience high levels of high-arousal negative emotion on average reported lower ER need compared with younger adults in poor physical health. However, older adults with lower cognitive resources who experience high levels of high-arousal negative emotion on average reported higher ER need.

DISCUSSION

Findings suggest that younger age and lower levels of cognitive ability are linked to less perceived need to regulate negative emotional states. Physical vulnerabilities also may dampen the perceived need for regulating high-arousal negative emotions, but only among older adults. Age-related shifts in resources and emotional goals may influence the likelihood that individuals are motivated to engage in ER, as well as the effectiveness of those efforts.

11β-HSD1 contributes to age-related metabolic decline in male mice

The aged phenotype shares several metabolic similarities with that of circulatory glucocorticoid excess (Cushing's syndrome), including type 2 diabetes, obesity, hypertension, and myopathy. We hypothesise that local tissue generation of glucocorticoids by 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1), which converts 11-dehydrocorticosterone to active corticosterone in rodents (corticosterone to cortisol in man), plays a role in driving age-related chronic disease. In this study, we have examined the impact of ageing on glucocorticoid metabolism, insulin tolerance, adiposity, muscle strength, and blood pressure in both wildtype (WT) and transgenic male mice with a global deletion of 11β-HSD1 (11β-HSD1-/-) following 4 months high-fat feeding. We found that high fat-fed 11β-HSD1-/- mice were protected from age-related glucose intolerance and hyperinsulinemia when compared to age/diet-matched WTs. By contrast, aged 11β-HSD1-/- mice were not protected from the onset of sarcopenia observed in the aged WTs. Young 11β-HSD1-/- mice were partially protected from diet-induced obesity; however, this partial protection was lost with age. Despite greater overall obesity, the aged 11β-HSD1-/- animals stored fat in more metabolically safer adipose depots as compared to the aged WTs. Serum analysis revealed both WT and 11β-HSD1-/- mice had an age-related increase in morning corticosterone. Surprisingly, 11β-HSD1 oxo-reductase activity in the liver and skeletal muscle was unchanged with age in WT mice and decreased in gonadal adipose tissue. These data suggest that deletion of 11β-HSD1 in high fat-fed, but not chow-fed, male mice protects from age-related insulin resistance and supports a metabolically favourable fat distribution.

Childhood abuse/neglect and temporal patterns in late-life anxiety

OBJECTIVES

Anxiety has been associated with childhood abuse/neglect, but this relationship and its mechanisms are poorly documented in older adults. This study examined the association between childhood abuse/neglect and late-life anxiety temporal patterns (i.e. absence, remission, incidence, persistence), testing for mediators.

METHODS

Data were derived for 724 French-speaking community-living older adults participating in the Étude sur la santé des ainés - Services study with available information at baseline and 4-year follow-up. Past-month anxiety was based on a cutoff score ≥5 on a French translation of the 7-item Generalized Anxiety Disorder at interviews. Questions on childhood abuse/neglect (e.g. psycho-emotional, physical, sexual) were administered. Adjusted multinomial regression analyses and mediation bootstrapping models were used. Tested mediators included traumatic events (excluding childhood abuse/neglect), daily hassles, psychological resilience, and cortisol activity.

RESULTS

The absence, remission, incidence and persistence of anxiety was found in 45.3%, 25.3%, 8.7% and 20.7% of the sample, respectively. Participants with incident and persistent late-life anxiety experienced more childhood abuse/neglect. Participants with persistent anxiety also reported lower psychological resilience. The association between childhood abuse/neglect with anxiety incidence was mediated by daily hassles, while its association with anxiety persistence was mediated by daily hassles and psychological resilience.

CONCLUSION

Past childhood abuse/neglect was associated with late-life anxiety incidence and persistence, with psychological resilience and daily hassles potentially explaining this relationship. Further research should focus on ascertaining the clinical applications of psychosocial and biological profiles in informing the prevention and personalized treatment of anxiety in older adults.

Aging, Social Distancing, and COVID-19 Risk: Who is more Vulnerable and Why?

Perceived social support represents an important predictor of healthy aging. The global COVID-19 pandemic has dramatically changed the face of social relationships and revealed elderly to be particularly vulnerable to the effects of social isolation. Social distancing may represent a double-edged sword for older adults, protecting them against COVID-19 infection while also sacrificing personal interaction and attention at a critical time. Here, we consider the moderating role of social relationships as a potential influence on stress resilience, allostatic load, and vulnerability to infection and adverse health outcomes in the elderly population. Understanding the mechanisms how social support enhances resilience to stress and promotes mental and physical health into old age will enable new preventive strategies. Targeted social interventions may provide effective relief from the impact of COVID-19-related isolation and loneliness. In this regard, a pandemic may also offer a window of opportunity for raising awareness and mobilizing resources for new strategies that help build resilience in our aging population and future generations.

Forty-eight-hour fasting declines mental flexibility but improves balance in overweight and obese older women

The purpose of this study was to investigate the effects of a 48-h fast on evoked stress, mood, and cognitive and motor functions in overweight and obese older women. Eleven women (body mass index >25 kg/m²) aged 63-80 years were tested under two randomly allocated conditions: 48-h zero-calorie diet with water provided ad libitum and 48-h usual diet. Autonomic function, cortisol levels, mood state, cognitive performance, visuomotor coordination, motor speed, and balance were evaluated before and after each diet. Fasting increased (P < 0.05) cortisol levels, whereas no changes were observed in heart rate and its variability. Fasting increased (P < 0.05) fatigue, prolonged (P < 0.05) reaction time in the two-choice reaction time test and decreased (P < 0.05) the velocity vector of the center of pressure with eyes closed, whereas no changes in performance were observed in the pursuit tracking and finger tapping tests. Thus, although a 48-h fast resulted in greater hypothalamic-pituitary-adrenal axis activity in overweight and obese older women, autonomic nervous system activity was not affected. Fasting increased fatigue and decreased mental flexibility, but improved balance.

Interleukin-2 drives cortisol secretion in an age-, dose-, and body composition-dependent way

BACKGROUND

Interleukin-2 (IL-2), one of the proinflammatory cytokines, is used in the treatment of certain malignancies. In some studies, transient increases in cortisol and ACTH secretion occurred. Thus, this agent may be used as an experimental probe of adrenal cortisol secretion.

OBJECTIVE

This study quantifies the effects of low and moderate doses of IL-2 on cortisol secretion and assesses the modulation by age, dose and body composition.

SITE

Mayo Clinical Translational Research Unit.

SUBJECTS

Study comprised 35 healthy men, 17 young and 18 older.

METHODS

Randomized prospective double-blind saline-controlled study of IL-2 administration in two doses with concurrent 10-min blood sampling for 24 h.

OUTCOME MEASURES

Deconvolution analysis and approximate entropy of cortisol secretion.

RESULTS

Low-dose IL-2 administration increased nocturnal pulsatile cortisol secretion from 1460 ± 160 to 2120 ± 220 nmol/L/8 h in young subjects and from 1680 ± 105 to 1960 ± 125 nmol/L/8 h (treatment P < 0.0001, but more in young than older, P = 0.02). Comparable results were obtained for total cortisol secretion (P treatment <0.0001, age effect P = 0.005). The higher IL-2 dose caused a large increase in young (P < 0.0001), but not in older (P = 0.90) subjects. This dose also increased approximate entropy from 0.877 ± 0.041 to 1.024 ± 0.049 (P = 0.008), pointing to reduced secretory orderliness. Incremental cortisol (nocturnal) secretion correlated negatively with visceral fat mass (R = -0.41, P = 0.019).

CONCLUSION

In healthy men, IL-2 injection drives pulsatile cortisol secretion in a dose-dependent way in young, but not older, individuals and erodes cortisol secretory orderliness at a higher dose in young subjects. Cortisol responses are diminished with increasing abdominal visceral fat mass.

Aging increases vulnerability to stress-induced depression via upregulation of NADPH oxidase in mice

Brain aging proceeds with cellular and molecular changes in the limbic system. Aging-dependent changes might affect emotion and stress coping, yet the underlying mechanisms remain unclear. Here, we show aged (18-month-old) mice exhibit upregulation of NADPH oxidase and oxidative stress in the hippocampus, which mirrors the changes in young (2-month-old) mice subjected to chronic stress. Aged mice that lack p47phox, a key subunit of NADPH oxidase, do not show increased oxidative stress. Aged mice exhibit depression-like behavior following weak stress that does not produce depressive behavior in young mice. Aged mice have reduced expression of the epigenetic factor SUV39H1 and its upstream regulator p-AMPK, and increased expression of Ppp2ca in the hippocampus-changes that occur in young mice exposed to chronic stress. SUV39H1 mediates stress- and aging-induced sustained upregulation of p47phox and oxidative stress. These results suggest that aging increases susceptibility to stress by upregulating NADPH oxidase in the hippocampus.

Sex differences in stress-related disorders: Major depressive disorder, bipolar disorder, and posttraumatic stress disorder

Stress-related disorders, such as mood disorders and posttraumatic stress disorder (PTSD), are more common in women than in men. This sex difference is at least partly due to the organizing effect of sex steroids during intrauterine development, while activating or inhibiting effects of circulating sex hormones in the postnatal period and adulthood also play a role. Such effects result in structural and functional changes in neuronal networks, neurotransmitters, and neuropeptides, which make the arousal- and stress-related brain systems more vulnerable to environmental stressful events in women. Certain brainstem nuclei, the amygdala, habenula, prefrontal cortex, and hypothalamus are important hubs in the stress-related neuronal network. Various hypothalamic nuclei play a central role in this sexually dimorphic network. This concerns not only the hypothalamus-pituitary-adrenal axis (HPA-axis), which integrates the neuro-endocrine-immune responses to stress, but also other hypothalamic nuclei and systems that play a key role in the symptoms of mood disorders, such as disordered day-night rhythm, lack of reward feelings, disturbed eating and sex, and disturbed cognitive functions. The present chapter focuses on the structural and functional sex differences that are present in the stress-related brain systems in mood disorders and PTSD, placing the HPA-axis in the center. The individual differences in the vulnerability of the discussed systems, caused by genetic and epigenetic developmental factors warrant further research to develop tailor-made therapeutic strategies.

Acute Cortisol Levels and Memory Performance in Older People with High and Normal Body Mass Index

Previous studies have shown that healthy older adults may be less sensitive to the effects of acute cortisol levels on memory performance than young adults. Importantly, being overweight has recently been associated with an increase in both cortisol concentration and cortisol receptors in central tissues, suggesting that Body Mass Index (BMI) may contribute to differences in the relationship between memory and acute cortisol. This study investigates the role of BMI in the relationship between memory performance and acute cortisol levels in older people (M = 64.70 years; SD = 4.24). We measured cortisol levels and memory performance (working memory and declarative memory) in 33 participants with normal BMI (normal BMI = 18.50-24.99) and 36 participants with overweight BMI (overweight BMI = 25-29.99). Overweight BMI participants showed worse performance on word-list learning (p = .036, 95% CI [0.08, 2.18], η2p = 0.07). Higher cortisol levels were related to higher proactive interference (β = .364, p = .016, 95% CI [0.07, 0.66]), and BMI did not moderate any of the relationships investigated. In accordance with previous studies, our results show worse memory performance in individuals with overweight BMI. However, our results do not support the idea that memory performance in older people with higher BMI may be more sensitive to differences in acute cortisol levels than in older people with normal BMI. More research is needed to test this hypothesis with obese individuals (BMI > 30 Kg/cm2).

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

Background and Objectives

According to the strength and vulnerability integration (SAVI) model, older people are better able to avoid negative social interactions than younger people, but when they do experience negative interactions, they are equally or more emotionally and physiologically reactive than younger people. Less is known about the links between daily negative and positive social encounters and the sympathetic adrenal medullary system (a key stress pathway) and whether there are age differences in these links. This study considers whether negative and positive social interactions are associated with diurnal alpha-amylase (a measure of the sympathetic adrenal medullary system) and whether there are differences in these links by age.

Research Design and Methods

Participants were from the Daily Health, Stress, and Relationship Study, which includes a random sample of 89 individuals (aged 40-95) who completed 14 days of daily diary interviews and provided saliva samples four times a day (wake, 30 min after wake, lunch, and bedtime) for four of those days that were assayed for alpha-amylase.

Results

Days in which people reported more negative interactions were associated with flatter morning declines in alpha-amylase, indicating greater stress. Links between positive interactions and diurnal alpha-amylase varied by age group.

Discussion and Implications

Findings are consistent with the SAVI model indicating that older adults respond differently to social stimuli than younger people.

Glucocorticoid Negative Feedback in Regulation of the Hypothalamic-Pituitary-Adrenal Axis in Rhesus Monkeys With Various Types of Adaptive Behavior: Individual and Age-Related Differences

The study of the mechanisms underlying the increased vulnerability of the individual to stressful environmental factors in different age periods is of great relevance for prevention and effective treatment of stress-dependent diseases that are widespread in the population of aging individuals. The purpose of our study was to investigate the individual and age-related features of the glucocorticoid negative feedback in regulation of the hypothalamic-pituitary-adrenal (HPA) axis, the key adaptive neuroendocrine system, in experiments with physically healthy young and old female rhesus monkeys with administration of mineracorticoid receptor (fludrocortisone) and glucocorticoid receptor (dexamethasone) agonists. We studied the monkeys with increased trait anxiety and depression-like behavior (DAB) characterized, as previously was shown, by the increased vulnerability to acute stress and the animals with normal standard behavior (SB) as the control. The pronounced individual differences in the reaction of HPA axis to fludrocortisone and dexamethasone in young animals were found. Young animals with DAB showed a lower sensitivity of HPA axis to the inhibitory effect of both fludrocortisone and dexamethasone compared with young animals with SB. At the same time, there were no significant intergroup differences in the concentration of ACTH and cortisol in response to placebo injection, i.e., in basal conditions. The old individuals with DAB demonstrated the essential relative resistance of HPA axis to fludrocortisone test and higher basal plasma levels of cortisol and ACTH in the evening (the period of HPA axis low circadian activity) compared to old SB animals. In the same time, the intergroup differences in the response of HPA axis to dexamethasone administration were leveled due to age-related increase in sensitivity of HPA axis to dexamethasone in animals with DAB. These data testify the pronounced intergroup and age differences in the feedback regulation of HPA axis, presumably resulting from unequal individual, and age-related changes in the activity of mineralcorticoid and glucocorticoid receptors in the brain structures supporting the functions of HPA axis. The maximum age disorders in functioning of the negative feedback mechanism in the regulation of HPA axis are characteristic of animals with DAB, which, apparently, underlie the increased vulnerability of these animals to stress exposure.

Memory Training Program Decreases the Circulating Level of Cortisol and Pro-inflammatory Cytokines in Healthy Older Adults

Aging cognitive decline has been associated to impairment of the Hypothalamus Pituitary Adrenals (HPA) axis activity and a higher level of the systemic inflammation. However, little is known about the molecules driving this process at peripheral level. In addition, the cognitive function is to some extent modifiable with Memory Training (MT) programs, even among older adults and beyond. The study aims to evaluate whether MT could contribute to ameliorate cognitive performance and modulate the HPA axis activity as well the low level inflammation in the aging phenotype. Whether the phosphatase WIP-1, a negative regulator for inflammation, is involved in this process was also investigated. We recruited 31 young adults (19-28, years of age) and 62 older adults aged over 60. Thirty-two older adults were submitted to 6-months of MT program (EG), and 28 older adults were no treated and used as Control Group (CG). Global cognitive functioning (MMSE score), verbal and visual memory, and attention were assessed at baseline (T0) and after 6-months (T1). At the same time, plasmatic level of Cortisol (C), IL-1β, IL-18, IL-6, and the expression of WIP-1 mRNA and protein in ex vivo Peripheral Blood Mononuclear Cells were analyzed in young adults at T0, as well in older adults at T0 and T1. Together, the results suggest that MT improves the global cognitive functionality, verbal and visual memory, as well as the level of attention. At the same time we observed a decrease of the plasmatic level of C, of the cytokines, and an increase of the expression of mRNA and protein of WIP-1. The analysis of correlations highlighted that the level of the mRNA of WIP-1 was positively associated to the MMSE score, and negatively to the C and cytokine levels. In conclusion, we purpose the MT as tool that could help support successful aging through the improving of memory, attention and global cognitive function performance. Furthermore, this approach could participate to maintain lower the peripheral levels of the C and pro-inflammatory cytokines. The WIP-1 as a potential new target of the pathophysiology of aging is theorized.

Mineralocorticoid receptor function in depressed patients and healthy individuals

BACKGROUND

Many studies have shown disturbed glucocorticoid receptor (GR) in depressed patients. In contrast, only few studies targeted mineralocorticoid receptor (MR) function with inconclusive results. We examined the effects of the MR antagonist spironolactone on cortisol secretion in depressed patients and healthy individuals.

METHODS

Forty-eight unmedicated depressed patients (mean age 41.6years) and 45 age- and sex-matched healthy participants (40.7years) received the MR antagonist spironolactone (300mg) or placebo with three days apart in a randomized, double-blind, within-subject cross-over design. We measured salivary cortisol before ingestion of study medication (baseline) as well as +60min, +90min, +120min, +150min and 180min after baseline.

RESULTS

Repeated-measures ANOVA for area under the curve (AUCg) cortisol revealed a treatment effect with higher cortisol after spironolactone and a treatment by group interaction. Post-hoc analyses revealed higher cortisol in depressed patients compared to healthy participants in the placebo condition. In the spironolactone condition, the cortisol levels were not significantly different.

CONCLUSIONS

Potentially, impaired MR or GR signaling could be responsible for higher cortisol levels in depressed patients in the placebo condition. However, after MR blockade that increased cortisol secretion across groups leading to higher GR occupation, we found no differences between depressed patients and healthy controls. Thus, our results argue for depression-associated alterations in MR signaling rather than disturbed GR-mediated feedback inhibition.

The acute effect of a mineralocorticoid receptor agonist on corticotrope secretion in Addison's disease

PURPOSE

Mineralocorticoid receptors (MR) in the hippocampus display an important role in the control of hypothalamic-pituitary-adrenal (HPA) axis, mediating the ''proactive'' feedback of glucocorticoids (GC). Fludrocortisone (FC), a potent MR agonist, has been shown to decrease HPA activity through a hippocampal mechanism. Since it has been demonstrated that FC shows a significant inhibition of the HPA axis response to hCRH stimulus in normal subjects, also at doses usually administered as replacement therapy in patients with Addison's disease, an FC effect at MRs in human pituitary or a GR-pituitary agonism stronger than believed until now has been postulated.

METHODS

Ten patients affected by autoimmune Addison's disease received: (1) placebo p.o. + placebo i.v., (2) hydrocortisone (H) 10 mg p.o. + placebo i.v., (3) FC 0.1 mg p.o. + placebo i.v., (4) FC 0.1 mg and H 10 mg p.o. + placebo i.v. to verify a possible GR FC-mediated effect that might display a repercussion on the GC-replacement therapy.

RESULTS

H reduced ACTH (p < 0.01) and increased cortisol levels (p < 0.01) with respect to the placebo session, while FC did not affect either ACTH or cortisol levels compared to placebo, and higher ACTH and lower cortisol levels (p < 0.03 and p < 0.01) were observed compared with the H session; furthermore the co-administration of FC + H showed ACTH and cortisol profiles similar to that observed during H alone.

CONCLUSIONS

Our study showed a lack of FC effect on corticotrope secretion in Addison's disease, thus making unlikely the hypothesis of its GR pituitary agonism and the risk of glucocorticoid excess in primary adrenal insufficiency.

Hypothalamic-pituitary-adrenal (HPA) axis and aging

Human aging is associated with increasing frailty and morbidity which can result in significant disability. Dysfunction of the hypothalamic-pituitary-adrenal (HPA) axis may contribute to aging-related diseases like depression, cognitive deficits, and Alzheimer's disease in some older individuals. In addition to neuro-cognitive dysfunction, it has also been associated with declining physical performance possibly due to sarcopenia. This article reviews the pathophysiology of HPA dysfunction with respect to increased basal adrenocorticotropic hormone (ACTH) and cortisol secretion, decreased glucocorticoid (GC) negative feedback at the level of the paraventricular nucleus (PVN) of the hypothalamus, hippocampus (HC), and prefrontal cortex (PFC), and flattening of diurnal pattern of cortisol release. It is possible that the increased cortisol secretion is secondary to peripheral conversion from cortisone. There is a decline in pregnolone secretion and C-19 steroids (DHEA) with aging. There is a small decrease in aldosterone with aging, but a subset of the older population have a genetic predisposition to develop hyperaldosteronism due to the increased ACTH stimulation. The understanding of the HPA axis and aging remains a complex area with conflicting studies leading to controversial interpretations.

Mineralocorticoid receptor haplotypes sex-dependently moderate depression susceptibility following childhood maltreatment

The MR is an important regulator of the hypothalamic-pituitary-adrenal (HPA) axis and a prime target for corticosteroids. There is increasing evidence from both clinical and preclinical studies that the MR has different effects on behavior and mood in males and females. To investigate the hypothesis that the MR sex-dependently influences the relation between childhood maltreatment and depression, we investigated three common and functional MR haplotypes (GA, CA, and CG haplotype, based on rs5522 and rs2070951) in a population-based cohort (N = 665) and an independent clinical cohort from the Netherlands Study of Depression and Anxiety (NESDA) (N = 1639). The CA haplotype sex-dependently moderated the relation between childhood maltreatment and depressive symptoms both in the population-based sample (sex × maltreatment × haplotype: β = -4.07, P = 0.029) and in the clinical sample (sex × maltreatment × haplotype, β = -2.40, P = 0.011). Specifically, female individuals in the population-based sample were protected (β = -4.58, P = 2.0 e(-5)), whereas males in the clinical sample were at increased risk (β = 2.54, P = 0.0022). In line with these results, female GA haplotype carriers displayed increased vulnerability in the population-based sample (β = 4.58, P = 7.5 e(-5)) whereas male CG-carriers showed increased resilience in the clinical sample (β = -2.71, P = 0.016). Consistently, we found a decreased lifetime MDD risk for male GA haplotype carriers following childhood maltreatment but an increased risk for male CA haplotype carriers in the clinical sample. In both samples, sex-dependent effects were observed for GA-GA diplotype carriers. In summary, sex plays an important role in determining whether functional genetic variation in MR is beneficial or detrimental, with an apparent female advantage for the CA haplotype but male advantage for the GA and CG haplotype. These sex-dependent effects of MR on depression susceptibility following childhood maltreatment are relevant in light of the increased prevalence of mood disorders in women and point to a sex-specific role of MR in the etiology of depression following childhood maltreatment.

The brain mineralocorticoid receptor and stress resilience

Stress exposure activates the HPA-axis and results in the release of corticosteroids which bind to two receptor types in the brain: the mineralocorticoid receptor (MR) and the glucocorticoid receptor (GR). While the role of the GR in stress reactivity has been extensively studied, the MR has received less attention. Nevertheless, pioneering in-depth studies over the past two decades have shown the importance of the brain MR in the processing of stressful information. Moreover, a membrane-bound MR mediating the rapid effects of cortisol was recently discovered. This review summarizes how the MR may play a role in stress resilience. Both preclinical and clinical studies suggest that the MR is an important stress modulator and influences basal as well as stress-induced HPA-axis activity, stress appraisal, and fear-related memories. These MR effects are mediated by both genomic and non-genomic MRs and appear to be at least partially sex-dependent. Moreover, the majority of studies indicate that high MR functionality or expression may confer resilience to traumatic stress. This has direct clinical implications. First, increasing activity or expression of brain MRs may prevent or reverse symptoms of stress-related depression. Second, individuals with a relatively low MR functionality may possess an increased stress susceptibility for depression. Nevertheless, the number of clinical MR studies is currently limited. In conclusion, the recent emergence of the MR as a putative stress resilience factor is important and may open up new avenues for the prevention and treatment of psychiatric disorders.

Acute stress and working memory in older people

Several studies have shown that acute stress affects working memory (WM) in young adults, but the effect in older people is understudied. As observed in other types of memory, older people may be less sensitive to acute effects of stress on WM. We performed two independent studies with healthy older men and women (from 55 to 77 years old) to investigate the effects of acute stress (Trier Social Stress Test; TSST) and cortisol on WM. In study 1 (n = 63), after the TSST women (but not men) improved their performance on Digit Span Forward (a measure of the memory span component of WM) but not on Digit Span Backward (a measure of both memory span and the executive component of WM). Furthermore, in women, cortisol levels at the moment of memory testing showed a positive association with the memory span component of WM before and after the TSST, and with the executive component of WM only before the stress task. In study 2 (n = 76), although participants showed a cortisol and salivary alpha-amylase (sAA) response to the TSST, stress did not affect performance on Letter-Number Sequencing (LNS; a task that places a high demand on the executive component of WM). Cortisol and sAA were not associated with WM. The results indicate that circulating cortisol levels at the moment of memory testing, and not the stress response, affect memory span in older women, and that stress and the increase in cortisol levels after stress do not affect the executive component of WM in older men and women. This study provides further evidence that older people may be less sensitive to stress and stress-induced cortisol response effects on memory processes.

Sleep EEG effects of anti-gluco- and anti-mineralocorticoids in old-aged men: pilot study

AIM

Age-related sleep changes have been associated with altered hypothalamic-pituitary-adrenal axis reactivity and impaired feedback inhibition at the glucocorticoid (GR) and mineralocorticoid (MR) receptor level. To further investigate the specific role of this binary receptor system in the elderly, sleep electroencephalogram (EEG) effects of the MR antagonist spironolactone and GR antagonist mifepristone in old-aged men were compared in this pilot study.

METHODS

Old-aged healthy men (n = 6, 65-91 years) were treated on three occasions in a single-blinded design in random order with mifepristone, spironolactone and placebo, respectively, and nocturnal sleep EEG was recorded.

RESULTS

Mifepristone led to increased wake time, decreased stage 2 and rapid eye movement (REM) sleep and prolonged REM sleep latency in the first half of the night, whereas spironolactone had no considerable effects on sleep EEG.

CONCLUSION

GR antagonism can potentiate age-related sleep pattern alterations and further support the role of impaired GR signaling in age-related changes in sleep architecture.

Emotional Experience Across Adulthood

Strength and vulnerability integration (SAVI) is a theoretical model that predicts changes in emotional experience across adulthood. A growing number of studies find that as people age, they become more adept at using thoughts and behaviors to avoid or mitigate exposure to negative experiences. People gradually acquire this expertise over a lifetime of experiences and are more motivated to regulate their emotions because of perceptions of time left to live. SAVI further posits that aging is associated with physiological vulnerabilities that make regulating high levels of emotional arousal more difficult. In situations in which people experience high levels of distress, age differences that normally favor older adults in the use of emotion-regulation strategies will be attenuated (and may even be nullified or reversed), and the physiological consequences of sustained emotional arousal will be more costly for older adults. In this article, we describe SAVI and discuss recent studies supporting its predictions.

The acute effect of fludrocortisone on basal and hCRH-stimulated hypothalamic--pituitary--adrenal (HPA) axis in humans

Mineralocorticoid receptors (MR) in the hippocampus display an important role in the control of hypothalamic-pituitary-adrenal (HPA)-axis, mediating the "proactive"-feedback of glucocorticoids. Fludrocortisone (FC), a potent MR agonist, has been shown to decrease HPA activity through a mechanism placed at hippocampal level. In order to clarify the effects of MR agonism on HPA function in humans, we studied the effects of FC, in a dose-related manner, on both basal and CRH-stimulated HPA axis during the quiescent phase. 8 young women were studied. ACTH, cortisol and aldosterone levels were evaluated every 15', from 1600 to 2000 hours, in randomized sessions: (1) placebo p.o. + placebo i.v., (2) 0.3 mg FC p.o. + placebo, (3) 0.1 mg FC. + placebo, (4) 0.075 mg FC + placebo, (5) 0.05 mg FC + placebo, (6) placebo + hCRH (2.0 μg/kg iv-bolus), (7) 0.3 mg FC + hCRH, (8) 0.1 mg FC + hCRH, (9) 0.075 mg FC + hCRH, (10) 0.05 mg FC + hCRH. FC induced a dose-related trend toward a further decrease of the ACTH and cortisol levels, while it showed a significant and dose-dependent inhibition of the hormonal response to hCRH (p < 0.05 for the doses of 0.3, 0.1 and 0.075 mg). Conversely, 0.05 mg FC did not modify the CRH-stimulatory effect on both ACTH and cortisol secretion. Aldosterone levels were not modified by FC administration. Fludrocortisone inhibits corticotrope and adrenal response to hCRH in humans, in a dose-dependent manner. The 0.075 mg FC seems the lowest active while 0.05 mg the first neutral dose on HPA activity. These data suggest a possible hypophysial MR-mediated inhibiting effect of FC, although its pituitary glucocorticoid-mediated effect cannot be excluded. The interplay between fludrocortisone and hypophysial glucocorticoid receptors needs to be clarified in order to define better the clinical consequences of the hormonal replacement therapy of patients with primary adrenal insufficiency.

11β-Hydroxysteroid dehydrogenase 1: translational and therapeutic aspects

11β-Hydroxysteroid dehydrogenase type 1 (11β-HSD1) interconverts the inactive glucocorticoid cortisone and its active form cortisol. It is widely expressed and, although bidirectional, in vivo it functions predominantly as an oxoreductase, generating active glucocorticoid. This allows glucocorticoid receptor activation to be regulated at a prereceptor level in a tissue-specific manner. In this review, we will discuss the enzymology and molecular biology of 11β-HSD1 and the molecular basis of cortisone reductase deficiencies. We will also address how altered 11β-HSD1 activity has been implicated in a number of disease states, and we will explore its role in the physiology and pathologies of different tissues. Finally, we will address the current status of selective 11β-HSD1 inhibitors that are in development and being tested in phase II trials for patients with the metabolic syndrome. Although the data are preliminary, therapeutic inhibition of 11β-HSD1 is also an exciting prospect for the treatment of a variety of other disorders such as osteoporosis, glaucoma, intracranial hypertension, and cognitive decline.

Age-dependent and gender-dependent regulation of hypothalamic-adrenocorticotropic-adrenal axis

Tightly regulated output of glucocorticoids is critical to maintaining immune competence, the structure of neurons, muscle, and bone, blood pressure, glucose homeostasis, work capacity, and vitality in the human and experimental animal. Age, sex steroids, gender, stress, body composition, and disease govern glucocorticoid availability through incompletely understood mechanisms. According to an ensemble concept of neuroendocrine regulation, successful stress adaptations require repeated incremental signaling adjustments among hypothalamic corticotropin-releasing hormone and arginine vasopressin, pituitary adrenocorticotropic hormone, and adrenal corticosteroids. Signals are transduced via (positive) feedforward and (negative) feedback effects. Age and gonadal steroids strongly modulate stress-adaptive glucocorticoid secretion by such interlinked pathways.

Changes in pituitary function with ageing and implications for patient care

The pituitary gland has a role in puberty, reproduction, stress-adaptive responses, sodium and water balance, uterine contractions, lactation, thyroid function, growth, body composition and skin pigmentation. Ageing is marked by initially subtle erosion of physiological signalling mechanisms, resulting in lower incremental secretory-burst amplitude, more disorderly patterns of pituitary hormone release and blunted 24 h rhythmic secretion. Almost all pituitary hormones are altered by ageing in humans, often in a manner dependent on sex, body composition, stress, comorbidity, intercurrent illness, medication use, physical frailty, caloric intake, immune status, level of exercise, and neurocognitive decline. The aim of this article is to critically discuss the mechanisms mediating clinical facets of changes in the hypothalamic-pituitary axis during ageing, and the extent to which confounding factors operate to obscure ageing-related effects.

Stress responsiveness of the hypothalamic-pituitary-adrenal axis: age-related features of the vasopressinergic regulation

The hypothalamic-pituitary-adrenal (HPA) axis plays a key role in adaptation to environmental stresses. Parvicellular neurons of the hypothalamic paraventricular nucleus secrete corticotrophin releasing hormone (CRH) and arginine vasopressin (AVP) into pituitary portal system; CRH and AVP stimulate adrenocorticotropic hormone (ACTH) release through specific G-protein-coupled membrane receptors on pituitary corticotrophs, CRHR1 for CRH and V1b for AVP; the adrenal gland cortex secretes glucocorticoids in response to ACTH. The glucocorticoids activate specific receptors in brain and peripheral tissues thereby triggering the necessary metabolic, immune, neuromodulatory, and behavioral changes to resist stress. While importance of CRH, as a key hypothalamic factor of HPA axis regulation in basal and stress conditions in most species, is generally recognized, role of AVP remains to be clarified. This review focuses on the role of AVP in the regulation of stress responsiveness of the HPA axis with emphasis on the effects of aging on vasopressinergic regulation of HPA axis stress responsiveness. Under most of the known stressors, AVP is necessary for acute ACTH secretion but in a context-specific manner. The current data on the AVP role in regulation of HPA responsiveness to chronic stress in adulthood are rather contradictory. The importance of the vasopressinergic regulation of the HPA stress responsiveness is greatest during fetal development, in neonatal period, and in the lactating adult. Aging associated with increased variability in several parameters of HPA function including basal state, responsiveness to stressors, and special testing. Reports on the possible role of the AVP/V1b receptor system in the increase of HPA axis hyperactivity with aging are contradictory and requires further research. Many contradictory results may be due to age and species differences in the HPA function of rodents and primates.

Role of mineralocorticoid receptors on the hypothalamus-pituitary-adrenal axis in humans

This clinical review will summarize the available data regarding the role of mineralocorticoid receptors (MRs) on the hypothalamus-pituitary-adrenal (HPA) axis control in physiological and pathological conditions and in the memory processes involved in the control and appraisal of a stress event. MRs are predominantly expressed in the limbic structures, with the hippocampus being the main localization, although MRs are also found at the hypothalamic level. It is known that hyppocampal MRs control the proactive feedback involved in the maintenance of the basal HPA activity, mainly at the nadir of the circadian rhythm. In physiological conditions, the administration of pharmacological doses of both MR antagonists and agonists is able to interact with the HPA activity, modifying the quiescent phase-nadir of the circadian rhythm, although some data in the literature do not support these observations. Also, in a physiological condition such as aging, an enhanced HPA axis activity is found in the time window, when MRs are predominantly occupied by cortisol circulating levels, possibly reflecting an MR impairment in this period of life. In pathology, major depression has been correlated to MR qualitative-quantitative alterations which could reflect differences on psychological and physiological responses, possibly predicting psychopathologies. Most of the remarks reported in this review seem to indicate, in agreement with animal data, a role played by MRs in the delicate control of the HPA axis in humans and the possible predisposition to the development of pathologies in case of their alterations.

Depressive symptoms, cortisol, and cognition during human aging: the role of negative aging perceptions

Depressive symptoms and memory impairments are associated with heightened stress hormone levels during aging. A factor that is related to memory deficits during aging is internalized negative aging stereotypes; the idea people have about the process of aging. In this study, we assessed the associations between internalized negative aging stereotypes, depressive symptoms, subjective and objective memory assessments, and cortisol concentration among older adults. Forty older adults aged between 58 and 85 years (18 females and 22 males; mean age ± SD: 71.25 ± 8.80 years) were assessed in this study. Measures of internalized negative aging stereotypes, depressive symptoms, and both subjective and objective memory performance were assessed. Salivary samples were obtained for measurement of cortisol concentration. Stepwise linear regressions were executed in our main analyses. Internalized negative aging stereotypes were associated with increased depressive symptoms and subjective memory complaints. No significant differences were observed for objective memory performance, or cortisol concentration. Internalized negative aging stereotypes are associated with increased depressive symptomatology and subjective complaints of memory; however, they do not predict increased cortisol concentration nor objective memory performance during aging. These results indicate that the mechanism underlying the association between internalized negative aging stereotypes and cognitive impairments may not be related to dysregulations of cortisol secretion among older adults.

Sexual differentiation of the human brain: relation to gender identity, sexual orientation and neuropsychiatric disorders

During the intrauterine period a testosterone surge masculinizes the fetal brain, whereas the absence of such a surge results in a feminine brain. As sexual differentiation of the brain takes place at a much later stage in development than sexual differentiation of the genitals, these two processes can be influenced independently of each other. Sex differences in cognition, gender identity (an individual's perception of their own sexual identity), sexual orientation (heterosexuality, homosexuality or bisexuality), and the risks of developing neuropsychiatric disorders are programmed into our brain during early development. There is no evidence that one's postnatal social environment plays a crucial role in gender identity or sexual orientation. We discuss the relationships between structural and functional sex differences of various brain areas and the way they change along with any changes in the supply of sex hormones on the one hand and sex differences in behavior in health and disease on the other.

Strength and vulnerability integration: a model of emotional well-being across adulthood

The following article presents the theoretical model of strength and vulnerability integration (SAVI) to explain factors that influence emotion regulation and emotional well-being across adulthood. The model posits that trajectories of adult development are marked by age-related enhancement in the use of strategies that serve to avoid or limit exposure to negative stimuli but by age-related vulnerabilities in situations that elicit high levels of sustained emotional arousal. When older adults avoid or reduce exposure to emotional distress, they often respond better than younger adults; when they experience high levels of sustained emotional arousal, however, age-related advantages in emotional well-being are attenuated, and older adults are hypothesized to have greater difficulties returning to homeostasis. SAVI provides a testable model to understand the literature on emotion and aging and to predict trajectories of emotional experience across the adult life span.

Neuroendocrine effects of citalopram, a selective serotonin re-uptake inhibitor, during lifespan in humans

OBJECTIVE

Serotonergic system contributes to the regulation of hypothalamus-pituitary-adrenal axis. In humans, serotonergic agonists increase PRL, ACTH, and cortisol, while serotonin (5HT) influence on GH is controversial. Central 5HT activity and neuroendocrine function change during lifespan.

DESIGN

To clarify the neuroendocrine response to 5HT across lifespan, we assessed ACTH, cortisol, DHEA, PRL, and GH responses to citalopram (CT) in young adults (YA) (no.=12, 29.2±1.7 yr mean±SEM), middle aged (MA) (no.=12, 54.3±0.9 yr), and elderly (ES) (no.=12, 69.3±0.9 yr) males. All the subjects received placebo (saline iv over 120 min) or CT (20 mg iv over 120 min). Blood samples were taken every 15 min up to 240 min.

RESULTS

During placebo, ACTH, cortisol, GH, and PRL were similar in all groups while DHEA showed an age-dependent reduction from middle age (p<0.001). During CT, ACTH, and cortisol were higher than during placebo in YA (p<0.05) and even more in MA (p<0.01 vs placebo, p<0.05 vs YA); in ES, the increase of both ACTH and cortisol (p<0.05 vs placebo) was lower than in MA (p<0.05) and higher than in YA (p<0.05 for cortisol only). No changes were observed for DHEA, GH, and PRL in any group.

CONCLUSIONS

Corticotrope response to CT is age-dependent in normal men, being amplified starting from middle age, suggesting precocious changes in the serotonergic neuroendocrine control during lifespan. CT is a useful tool to evaluate the age-dependent serotonergic function in humans.

Basal hypothalamic pituitary adrenal axis activity and hippocampal volumes: the SMART-Medea study

BACKGROUND

It has frequently been hypothesized that high levels of glucocorticoids have deleterious effects on the hippocampus and increase risk for cognitive decline and dementia, but no large-scale studies in humans have examined the direct relation between hippocampal volumes and hypothalamic-pituitary-adrenal axis activity.

METHODS

Cross-sectional analyses within the Second Manifestations of ARTerial disease-Magnetic Resonance (SMART)-Medea study, an ancillary study to the SMART-MR study on brain changes on magnetic resonance imaging (MRI) among patients with arterial disease. In 575 patients (mean age 62 +/- 9 years), diurnal cortisol rhythm was assessed with six saliva samples, collected at awakening; at 30, 45, and 60 min thereafter; and at 10 pm and 11 pm. A low dose of dexamethasone (.5 mg) was administered at 11 pm, and saliva was sampled the next morning at awakening. Volumetric measurements of the hippocampus were performed on a three-dimensional fast field echo T1-weighted scan with isotropic voxels.

RESULTS

Mean total relative hippocampal volume was 6.0 +/- .7 mL. Linear regression analyses, adjusted for age, sex, vascular risk factors, and global brain atrophy showed that participants with higher evening levels and higher awakening levels after dexamethasone had smaller hippocampal volumes [B per SD (4.2) increase = -.09 mL; 95% confidence interval -.15 to -.03 mL and B per SD (2.5) increase = -.07 mL; 95% confidence interval -.13 to -.01 mL, respectively]. The awakening response was not significantly associated with hippocampal volumes.

CONCLUSIONS

In this population, higher evening cortisol levels and reduced suppression after dexamethasone were associated with smaller hippocampal volumes, independent of total brain volume. The cortisol response after awakening was not associated with hippocampal volume.

Effect of acute and prolonged mineralocorticoid receptor blockade on spontaneous and stimulated hypothalamic-pituitary-adrenal axis in humans

CONTEXT

Mineralocorticoid receptors (MRs) in the hippocampus display an important role in the control of the hypothalamic-pituitary-adrenal (HPA) axis, mediating the proactive feedback of glucocorticoids, which maintains the basal HPA activity. The systemic administration of MR antagonists enhances spontaneous and CRH-stimulated ACTH, cortisol, and DHEA secretion, while the effects of chronic treatment with MR antagonists are scanty. Our study was performed in order to clarify this point.

DESIGN

ACTH, cortisol, and DHEA levels were studied during the infusion of placebo, canrenoate, a MR antagonist (CAN, 200 mg i.v. bolus at 1600 h followed by 200 mg infused over 4 h), and human CRH (hCRH; 2.0 microg/kg i.v. bolus at 1800 h) before and during the last week of 28-day treatment with CAN (200 mg/day p.o.) in eight young women.

RESULTS

Pre-treatment sessions: CAN and hCRH administration increased ACTH, cortisol, and DHEA levels versus placebo (P<0.05). Post-treatment sessions: during placebo infusion, cortisol and DHEA were significantly amplified versus pre-treatment session (P<0.05), while ACTH levels were not modified; CAN infusion, differently from pre-treatment session, was not able to significantly increase ACTH, cortisol, and DHEA levels; ACTH, cortisol, and DHEA responses to hCRH were amplified with respect to pre-treatment session, although statistical significance was obtained for cortisol and DHEA only.

CONCLUSIONS

MR blockade by acute CAN administration significantly enhances the HPA activity in the afternoon, during the quiescent phase of the circadian rhythm. At the same period, prolonged treatment with CAN amplifies both spontaneous and CRH-stimulated activities of the HPA axis, while it blunts the HPA responsiveness to a further MR-mediated stimulation.

Social and emotional aging

The past several decades have witnessed unidimensional decline models of aging give way to life-span developmental models that consider how specific processes and strategies facilitate adaptive aging. In part, this shift was provoked by the stark contrast between findings that clearly demonstrate decreased biological, physiological, and cognitive capacity and those suggesting that people are generally satisfied in old age and experience relatively high levels of emotional well-being. In recent years, this supposed "paradox" of aging has been reconciled through careful theoretical analysis and empirical investigation. Viewing aging as adaptation sheds light on resilience, well-being, and emotional distress across adulthood.

Brain development under stress: hypotheses of glucocorticoid actions revisited

One of the conundrums in today's stress research is why some individuals flourish and others perish under similar stressful conditions. It is recognized that this individual variability in adaptation to stress depends on the outcome of the interaction of genetic and cognitive/emotional inputs in which glucocorticoid hormones and receptors play a crucial role. Hence one approach towards understanding individual variation in stress coping is how glucocorticoid actions can change from protective to harmful. To address this question we focus on four hypotheses that are connected and not mutual exclusive. First, the classical Glucocorticoid Cascade Hypothesis, in which the inability to cope with chronic stress causes a vicious cycle of excess glucocorticoid and downregulation of glucocorticoid receptors (GR) in the hippocampus triggering a feed-forward cascade of degeneration and disease. Second, the Balance Hypothesis, which takes also the limbic mineralocorticoid receptors (MR) into account and proposes that an integral limbic MR:GR imbalance is causal to altered processing of information in circuits underlying fear, reward, social behaviour and resilience, dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis and impairment of behavioural adaptation. The MR:GR balance is altered by gene variants of these receptor complexes and experience-related factors, which can induce lasting epigenetic changes in the expression of these receptors. A particular potent epigenetic stimulus is the maternal environment which is fundamental for the Maternal Mediation Hypothesis. The outcome of perinatal gene x environment interaction, and thus of MR:GR-mediated functions depends however, on the degree of 'matching' with environmental demands in later life. The Predictive Adaptation Hypothesis therefore presents a conceptual framework to examine the role of glucocorticoids in understanding individual phenotypic differences in stress-related behaviours over the lifespan.

Salivary cortisol differs with age and sex and shows inverse associations with WHR in Swedish women: a cross-sectional study

BACKGROUND

Most studies on cortisol have focused on smaller, selected samples. We therefore aimed to sex-specifically study the diurnal cortisol pattern and explore its association with abdominal obesity in a large unselected population.

METHODS

In 2001-2004, 1811 men and women (30-75 years) were randomly selected from the Vara population, south-western Sweden (81% participation rate). Of these, 1671 subjects with full information on basal morning and evening salivary cortisol and anthropometric measurements were included in this cross-sectional study. Differences between groups were examined by general linear model and by logistic and linear regression analyses.

RESULTS

Morning and Delta-cortisol (morning - evening cortisol) were significantly higher in women than men. In both genders older age was significantly associated with higher levels of all cortisol measures, however, most consistently with evening cortisol. In women only, age-adjusted means of WHR were significantly lower in the highest compared to the lowest quartile of morning cortisol (p = 0.036) and Delta-cortisol (p < 0.001), respectively. Furthermore, when comparing WHR above and below the mean, the age-adjusted OR in women for the lowest quartile of cortisol compared to the highest was 1.5 (1.0-2.2, p = 0.058) for morning cortisol and 1.9 (1.3-2.8) for Delta-cortisol. All findings for Delta-cortisol remained after adjustments for multiple covariates and were also seen in a linear regression analysis (p = 0.003).

CONCLUSION

In summary, our findings of generally higher cortisol levels in women than men of all ages are novel and the stronger results seen for Delta-cortisol as opposed to morning cortisol in the association with WHR emphasise the need of studying cortisol variation intra-individually. To our knowledge, the associations in this study have never before been investigated in such a large population sample of both men and women. Our results therefore offer important knowledge on the descriptive characteristics of cortisol in relation to age and gender, and on the impact that associations previously seen between cortisol and abdominal obesity in smaller, selected samples have on a population level.

Characterization of a novel gain of function glucocorticoid receptor knock-in mouse

Glucocorticoids (GCs) exert profound influences on many physiologic functions by virtue of their diverse roles in growth, development, and maintenance of homeostasis. We previously created a novel gain of function in the human glucocorticoid receptor (hGR), hGRM604L, which is active at GC concentrations 5-10-fold lower than wild-type GR. To gain a greater insight into GC physiology in vivo, we inserted this mutant GR (GRM610L in mice) into mice via homologous recombination. Mice expressing the allele are phenotypically normal with respect to GC function. However, corticosterone levels, ACTH levels, and adrenocortical size are markedly reduced, suggesting they are phenotypically normal because the mutant GR alters the basal regulation of the hypothalamic-pituitary-adrenal axis. We demonstrate via physiologic and immunologic studies that GRM610L mice have increased sensitivity to GCs in vivo. Sensitivity to the actions of endogenous GCs may be an important factor underlying the development of many human diseases including hypertension, obesity, and diabetes. Our model may provide a new and powerful tool for the study of GC physiological and pathological processes in vivo.

Atypical evening cortisol profile induces visual recognition memory deficit in healthy human subjects

BACKGROUND

Diurnal rhythm-mediated endogenous cortisol levels in humans are characterised by a peak in secretion after awakening that declines throughout the day to an evening trough. However, a significant proportion of the population exhibits an atypical cycle of diurnal cortisol due to shift work, jet-lag, aging, and mental illness.

RESULTS

The present study has demonstrated a correlation between elevation of cortisol in the evening and deterioration of visual object recognition memory. However, high evening cortisol levels have no effect on spatial memory.

CONCLUSION

This study suggests that atypical evening salivary cortisol levels have an important role in the early deterioration of recognition memory. The loss of recognition memory, which is vital for everyday life, is a major symptom of the amnesic syndrome and early stages of Alzheimer's disease. Therefore, this study will promote a potential physiologic marker of early deterioration of recognition memory and a possible diagnostic strategy for Alzheimer's disease.

The stress system in depression and neurodegeneration: focus on the human hypothalamus

The stress response is mediated by the hypothalamo-pituitary-adrenal (HPA) system. Activity of the corticotropin-releasing hormone (CRH) neurons in the hypothalamic paraventricular nucleus (PVN) forms the basis of the activity of the HPA-axis. The CRH neurons induce adrenocorticotropin (ACTH) release from the pituitary, which subsequently causes cortisol release from the adrenal cortex. The CRH neurons co-express vasopressin (AVP) which potentiates the CRH effects. CRH neurons project not only to the median eminence but also into brain areas where they, e.g., regulate the adrenal innervation of the autonomic system and affect mood. The hypothalamo-neurohypophysial system is also involved in stress response. It releases AVP from the PVN and the supraoptic nucleus (SON) and oxytocin (OXT) from the PVN via the neurohypophysis into the bloodstream. The suprachiasmatic nucleus (SCN), the hypothalamic clock, is responsible for the rhythmic changes of the stress system. Both centrally released CRH and increased levels of cortisol contribute to the signs and symptoms of depression. Symptoms of depression can be induced in experimental animals by intracerebroventricular injection of CRH. Depression is also a frequent side effect of glucocorticoid treatment and of the symptoms of Cushing's syndrome. The AVP neurons in the hypothalamic PVN and SON are also activated in depression, which contributes to the increased release of ACTH from the pituitary. Increased levels of circulating AVP are also associated with the risk for suicide. The prevalence, incidence and morbidity risk for depression are higher in females than in males and fluctuations in sex hormone levels are considered to be involved in the etiology. About 40% of the activated CRH neurons in mood disorders co-express nuclear estrogen receptor (ER)-alpha in the PVN, while estrogen-responsive elements have been found in the CRH gene promoter region, and estrogens stimulate CRH production. An androgen-responsive element in the CRH gene promoter region initiates a suppressing effect on CRH expression. The decreased activity of the SCN is the basis for the disturbances of circadian and circannual fluctuations in mood, sleep and hormonal rhythms found in depression. Neuronal loss was also reported in the hippocampus of stressed or corticosteroid-treated rodents and primates. Because of the inhibitory control of the hippocampus on the HPA-axis, damage to this structure was expected to disinhibit the HPA-axis, and to cause a positive feedforward cascade of increasing glucocorticoid levels over time. This 'glucocorticoid cascade hypothesis' of stress and hippocampal damage was proposed to be causally involved in age-related accumulation of hippocampal damage in disorders like Alzheimer's disease and depression. However, in postmortem studies we could not find the presumed hippocampal damage of steroid overexposure in either depressed patients or in patients treated with synthetic steroids.

Gender difference in age-related number of corticotropin-releasing hormone-expressing neurons in the human hypothalamic paraventricular nucleus and the role of sex hormones

Previous studies have shown that the total number of corticotropin-releasing hormone (CRH)-stained neurons in the human hypothalamic paraventricular nucleus (PVN) increases with age. To determine whether this age-related change depends on gender and whether circulating sex hormones play a role, we analyzed the total number of CRH-immunoreactive neurons by means of immunocytochemistry and image analysis in the postmortem hypothalamic PVN of 22 control subjects (11 males and 11 females) between the ages of 22 and 89 years, and of 10 subjects with abnormal sex hormone status. Our data show that men have a significantly larger number of CRH neurons than women (p = 0.004) and that the total number of CRH neurons increases significantly with age, but only in male controls (p = 0.032), not in female controls (p = 0.733). Female controls do not show a significant change in the total number of CRH neurons either before or after the age (50 years) of menopause (p = 0.792). Male subjects with low testosterone levels due to castration showed significantly fewer CRH neurons than well-matched intact males (p = 0.008), while castrated male-to-female (M-F) transsexuals with estrogen replacement showed normal numbers of CRH neurons. One male case, who had high estrogen levels due to an estrogen-producing tumor, showed a large number of CRH neurons. Thus, although circulating androgens and estrogens both seem to play a stimulatory role with respect to CRH neurons, the age-dependent increase in the number of CRH neurons in the PVN of men, which has been interpreted to reflect activation of the CRH neurons with age, seems to result from factors other than age-related changes of circulating sex hormone levels.

The low-dose dexamethasone suppression test in fibromyalgia

OBJECTIVE

Fibromyalgia syndrome (FMS) has been associated with decreased cortisol secretion. Patients with posttraumatic stress disorder (PTSD) exhibit similar hypocortisolism in the context of increased negative feedback sensitivity of the hypothalamic-pituitary-adrenal (HPA) axis. Because trauma and PTSD have been associated with fibromyalgia, we evaluated whether patients with fibromyalgia demonstrate increased HPA feedback sensitivity.

METHOD

Baseline blood samples were obtained at 0800 h, and 0.5 mg of dexamethasone was administered to 15 female patients with FMS and 20 normal controls at 2300 h. Adrenocorticotropin (ACTH), cortisol, and dexamethasone levels were measured at 0800 h after dexamethasone intake.

RESULTS

There were no group differences in mean ACTH or cortisol levels or in ACTH/cortisol ratio at baseline. After dexamethasone intake, patients with FMS exhibited more pronounced suppression of cortisol but not of ACTH, as well as increased ACTH/cortisol ratios compared with controls. Percent cortisol suppression was associated with pain and fatigue, while ACTH/cortisol ratio and dexamethasone availability were associated with stress and anxiety measures.

CONCLUSION

Our results suggest increased sensitivity to glucocorticoid feedback, manifested at the adrenal level, in FMS.

Diurnal cycle of salivary cortisol in older adult men and women with subjective complaints of memory deficits and/or depressive symptoms: relation to cognitive functioning

In populations of young and older adults, it has been shown that individuals may be categorized into one of three diurnal subgroups when salivary cortisol levels are assessed over a 2-day period and compared for their consistency across days: a typical subgroup, a flat subgroup, and an inconsistent subgroup. Interestingly, recent studies have reported that the typical subgroup represents the majority of the young and older adult population, a finding that is difficult to reconcile with previous studies showing increased cortisol levels in older adults with depression or cognitive impairments. In order to assess whether a typical diurnal cortisol profile is representative across different subgroups of older adults, we assessed diurnal cortisol cycle representation in a sample of older adults with subjective complaints of depression and/or memory problems. Furthermore, given the robust relationship between cortisol and cognitive function, the present study examined the association between the three diurnal subgroups and cognitive performance. Forty-two older individuals were recruited on the basis of reporting subjective complaints of either memory problems and/or depressive mood. Participants were asked to sample their saliva over a 2-day period and were then asked to undergo a neuropsychological evaluation that taps into short-term memory, declarative memory and language. The results showed that 69% of the sample presented a Flat cycle of salivary cortisol over a 2-day period while 19% presented an inconsistent pattern and 12% presented a typical pattern. Participants in the flat subgroup were significantly impaired on letter verbal fluency. Furthermore, a relationship was found between diurnal cortisol subgroup representation and subjective complaint profile. These findings show that older adults with complaints of memory problems and/or depressive symptoms do not present the typical profile of the diurnal cortisol cycle, and they provide a preliminary view of how diurnal cortisol profile relates to cognitive function during human aging.