Fetal brain 11β-hydroxysteroid dehydrogenase type 2 selectively determines programming of adult depressive-like behaviors and cognitive function, but not anxiety behaviors in male mice

Glucocorticoid effects on the brain: from adaptive developmental plasticity to allostatic overload

Exposure to stress during early life may alter the developmental trajectory of an animal by a mechanism known as adaptive plasticity. For example, to enhance reproductive success in an adverse environment, it is known that animals accelerate their growth during development. However, these short-term fitness benefits are often associated with reduced longevity, a phenomenon known as the growth rate-lifespan trade-off. In humans, early life stress exposure compromises health later in life and increases disease susceptibility. Glucocorticoids (GCs) are major stress hormones implicated in these processes. This Review discusses the evidence for GC-mediated adaptive plasticity in development, leading to allostatic overload in later life. We focus on GC-induced effects on brain structure and function, including neurogenesis; highlight the need for longitudinal studies; and discuss approaches to identify molecular mechanisms mediating GC-induced alteration of the brain developmental trajectory leading to adult dysfunctions. Further understanding of how stress and GC exposure can alter developmental trajectories at the molecular and cellular level is of critical importance to reduce the burden of mental and physical ill health across the life course.

Independent and Combined Effects of Prenatal Alcohol Exposure and Prenatal Stress on Fetal HPA Axis Development

Prenatal alcohol exposure (PAE) and prenatal stress (PS) are highly prevalent conditions known to affect fetal programming of the hypothalamic-pituitary-adrenal (HPA) axis. The objectives of this study were to assess the effect of light PAE, PS, and PAE-PS interaction on fetal HPA axis activity assessed via placental and umbilical cord blood biomarkers. Participants of the ENRICH-2 cohort were recruited during the second trimester and classified into the PAE and unexposed control groups. PS was assessed by the Perceived Stress Scale. Placental tissue was collected promptly after delivery; gene and protein analysis for 11β-HSD1, 11β-HSD2, and pCRH were conducted by qPCR and ELISA, respectively. Umbilical cord blood was analyzed for cortisone and cortisol. Pearson correlation and multivariable linear regression examined the association of PAE and PS with HPA axis biomarkers. Mean alcohol consumption in the PAE group was ~2 drinks/week. Higher PS was observed in the PAE group (p < 0.01). In multivariable modeling, PS was associated with pCRH gene expression (β = 0.006, p < 0.01), while PAE was associated with 11β-HSD2 protein expression (β = 0.56, p < 0.01). A significant alcohol-by-stress interaction was observed with respect to 11β-HSD2 protein expression (p < 0.01). Results indicate that PAE and PS may independently and in combination affect fetal programming of the HPA axis.

11β-Hydroxysteroid dehydrogenase and the brain: Not (yet) lost in translation

11-beta-hydroxysteroid dehydrogenases (11β-HSDs) catalyse the conversion of active 11-hydroxy glucocorticoids (cortisol, corticosterone) and their inert 11-keto forms (cortisone, 11-dehydrocorticosterone). They were first reported in the body and brain 70 years ago, but only recently have they become of interest. 11β-HSD2 is a dehydrogenase, potently inactivating glucocorticoids. In the kidney, 11β-HSD2 generates the aldosterone-specificity of intrinsically non-selective mineralocorticoid receptors. 11β-HSD2 also protects the developing foetal brain and body from premature glucocorticoid exposure, which otherwise engenders the programming of neuropsychiatric and cardio-metabolic disease risks. In the adult CNS, 11β-HSD2 is confined to a part of the brain stem where it generates aldosterone-specific central control of salt appetite and perhaps blood pressure. 11β-HSD1 is a reductase, amplifying active glucocorticoid levels within brain cells, notably in the cortex, hippocampus and amygdala, paralleling its metabolic functions in peripheral tissues. 11β-HSD1 is elevated in the ageing rodent and, less certainly, human forebrain. Transgenic models show this rise contributes to age-related cognitive decline, at least in mice. 11β-HSD1 inhibition robustly improves memory in healthy and pathological ageing rodent models and is showing initial promising results in phase II studies of healthy elderly people. Larger trials are needed to confirm and clarify the magnitude of effect and define target populations. The next decade will be crucial in determining how this tale ends - in new treatments or disappointment.

Maternal glucocorticoids do not directly mediate the effects of maternal social stress on the fetus

Stress during pregnancy negatively affects the fetus and increases the risk for affective disorders in adulthood. Excess maternal glucocorticoids are thought to mediate fetal programming; however, whether they exert their effects directly or indirectly remains unclear. During pregnancy, protective mechanisms including maternal hypothalamic-pituitary-adrenal (HPA) axis hyporesponsiveness and placental 11β-hydroxysteroid dehydrogenase (11βHSD) type 2, which inactivates glucocorticoids, limit mother-to-fetus glucocorticoid transfer. However, whether repeated stress negatively impacts these mechanisms is not known. Pregnant rats were exposed to repeated social stress on gestational days (GD) 16-20 and several aspects of HPA axis and glucocorticoid regulation, including concentrations of glucocorticoids, gene expression for their receptors (Nr3c1, Nr3c2), receptor chaperones (Fkbp51, Fkbp52) and enzymes that control local glucocorticoid availability (Hsd11b1, Hsd11b2), were investigated in the maternal, placental and fetal compartments on GD20. The maternal HPA axis was activated following stress, though the primary driver was vasopressin, rather than corticotropin-releasing hormone. Despite the stress-induced increase in circulating corticosterone in the dams, only a modest increase was detected in the circulation of female fetuses, with no change in the fetal brain of either sex. Moreover, there was no change in the expression of genes that mediate glucocorticoid actions or modulate local concentrations in the fetal brain. In the placenta labyrinth zone, stress increased Hsd11b2 expression only in males and Fkbp51 expression only in females. Our results indicate that any role glucocorticoids play in fetal programming is likely indirect, perhaps through sex-dependent alterations in placental gene expression, rather than exerting effects via direct crossover into the fetal brain.

The in-utero experience of piglets born from sows with lameness shapes their life trajectory

Experiences during gestation can alter the mother's behavior and physiology, thereby potentially affecting the behavioral and physiological development of the offspring. In livestock, one common challenge for pregnant animals is lameness: a multifactorial condition that causes pain, stress, resulting in poor welfare outcomes. Since maternal pain can affect offspring development, we aimed to quantify the behavioral response in 142 piglets born from sows with different degrees of lameness during pregnancy. Gait scores of 22 pregnant group-housed sows were assessed six times at 2-week intervals. Lameness scores varied from 0 (no lameness) to 5 (most severe lameness score). Saliva samples and behavior were assessed in the sows throughout pregnancy. Sows were moved to individual farrowing pens and placental tissue was collected for glucocorticoid assessment. At 28 days of age, piglets were weaned, weighed, and regrouped by body size and sex. Skin lesions were counted for each piglet on days 28, 29, and 30 after birth. During open field and novel object tests on day 30, the vocalization and activity levels were evaluated. Piglet data were grouped by the lameness score of the sows as G1 (without lameness), G2 (moderate lameness), and G3 (severe lameness). Data analysis included ANOVA or Kruskal-Wallis tests and pairwise comparisons which were performed using Tukey and Kramer (Nemenyi) test with Tukey-Dist approximation for independent samples. G2 piglets were heavier than G3 at weaning. G1 piglets had fewer skin lesions at days 28 and 29 than G2 piglets. Moreover, G1 piglets vocalized more than G2 when they were subjected to the combined open field and novel object test. We did not identify differences among sows showing different lameness scores in the concentration of placental or salivary glucocorticoids. Lameness in pregnant sows altered the offspring's weight gain, number of skin lesions and vocalizations, together showing evidence that lameness in sows affect offspring performance and behavior.

Fetal programming pathway from maternal mental health to infant cortisol functioning: The role of placental 11β-HSD2 mRNA expression

Placental 11β-HSD2 has been a focus of research for understanding potential fetal programming associated with maternal emotional disorders. This study examined the pathway from antenatal mental health via placental 11β-HSD2 mRNA to cortisol regulation in the infant offspring. This study reports on data obtained from 236 participants in the Mercy Pregnancy and Emotional Wellbeing Study (MPEWS). At term, placental tissue was collected within 30 min of birth from 52 participants meeting current criteria for a depressive disorder, and 184 control participants. Depressive disorders were diagnosed using the SCID-IV. In addition, antidepressant use, depressive and anxiety symptoms were measured in early and late pregnancy. Placental 11β-HSD2 mRNA expression was measured using qRT-PCR. Infant salivary cortisol samples were taken at 12 months of age. Women on antidepressant medication and with higher trait anxiety had higher placental 11β-HSD2 expression compared to women not taking medication. Furthermore, the offspring of women taking an antidepressant and who also had a current depressive disorder and high trait anxiety had high cortisol reactivity at 12 months of age and this was mediated through 11β-HSD2 mRNA expression. In contrast, offspring of women not taking antidepressant medication with depressive disorder and high anxiety there was low cortisol reactivity observed. Our findings suggest that the relationship between maternal antenatal depression and anxiety and infant cortisol reactivity is mediated through placental 11β-HSD2 mRNA expression. Furthermore, the direction differed for women taking antidepressants, where infant cortisol reactivity was high whereas when compared to those with unmedicated depression and anxiety, where infant cortisol reactivity was low.

Late gestational exposure to dexamethasone and fetal programming of abnormal behavior in Wistar Kyoto rats

INTRODUCTION

Fetal programming was characterized a few decades ago, explaining the correlation of physiological phenotypes of offspring exposed to early-life stress. High acute or chronic prenatal stress can overwhelm the enzymatic placental barrier, inducing transcriptional changes in the fetus that can result in different adverse behavioral and physiological phenotypes. The current study investigates the impact of exposure to the synthetic glucocorticoid, dexamethasone, during late gestation on behavioral outcomes.

METHODS

Pregnant Wistar Kyoto rats were given daily subcutaneous injections from gestational days 15-21 of either dexamethasone (0.9% NaCl, 4% EtOH, 100 µg kg^-1  day^-1 ) or were physically manipulated as naïve controls. Pups were raised normally until 17 weeks of age and underwent the Porsolt swim task and elevated plus maze for depressive and anxiety-like behaviors, respectively. Neural tissue was preserved for genetic analysis using quantitative real-time polymerase chain reaction.

RESULTS

Statistical analyses show significant disruption of behavior and genetic profiles of offspring exposed to dexamethasone in-utero. Exposed animals spent more time immobile on the swim task and entered open arms of the elevated plus maze more often than their naïve counterparts. In the prefrontal cortex, there was a sex by treatment interaction on gene expression relevant to neural transmission in ryanodine receptor 2, as well as increased gene expression in SNAP25, COMT, and LSAMP in males prenatally exposed to dexamethasone compared with controls. Both dysregulated genes and behavior are linked to decreased anxiety and fear inhibition.

CONCLUSION

Our results indicate adult offspring exposed to dexamethasone in-utero have a tendency toward passive stress-coping strategies and an inhibition of anxiety on behavioral tasks. Methyltransferase activity, synaptic activity, and cellular processes were disrupted in the prefrontal cortices of these animals. Specifically, genes involved in emotional response pathways were overexpressed, supporting the link between the behavioral and genetic profiles. Combined, we determine that dexamethasone offspring have adaptive predispositions when faced with novel situations, with increased immobility in the swim task and increased exploration on the elevated plus maze.

Premature Birth and Developmental Programming: Mechanisms of Resilience and Vulnerability

The third trimester of pregnancy represents a sensitive phase for infant brain plasticity when a series of fast-developing cellular events (synaptogenesis, neuronal migration, and myelination) regulates the development of neural circuits. Throughout this dynamic period of growth and development, the human brain is susceptible to stress. Preterm infants are born with an immature brain and are, while admitted to the neonatal intensive care unit, precociously exposed to stressful procedures. Postnatal stress may contribute to altered programming of the brain, including key systems such as the hypothalamic-pituitary-adrenal axis and the autonomic nervous system. These neurobiological systems are promising markers for the etiology of several affective and social psychopathologies. As preterm birth interferes with early development of stress-regulatory systems, early interventions might strengthen resilience factors and might help reduce the detrimental effects of chronic stress exposure. Here we will review the impact of stress following premature birth on the programming of neurobiological systems and discuss possible stress-related neural circuits and pathways involved in resilience and vulnerability. Finally, we discuss opportunities for early intervention and future studies.

Cognitive Improvement by Vorinostat through Modulation of Endoplasmic Reticulum Stress in a Corticosterone-Induced Chronic Stress Model in Mice

Chronic stress is the leading cause of memory impairment today. Various stress-based models are being developed for studying cognitive impairment. Repurposing of existing drugs in a new pharmacology class is the safest and cheapest option for treatment instead of new drug discovery. Vorinostat (VOR) is the first histone deacetylase (HDAC) inhibitor approved for the treatment of cutaneous T-cell lymphoma by the U.S. FDA. VOR follows the rule of five and is reported to cross the blood-brain barrier. Therefore, we aimed to evaluate the procognitive potential of VOR (25 mg/kg) administered by intraperitoneal (ip) route in a stress-based model of chronic corticosterone (CORT) injections (20 mg/kg, subcutaneously (sc)). The study comprised six groups. Normal mice were administered vehicle (VEH) (days 1-21, sc) in the first group, VOR (days 8-21, 25 mg/kg, ip) in the second group, and fluoxetine (FLX) (days 8-21, 15 mg/kg, oral) in the third group. Mice in the remaining three groups were given 20 mg/kg (sc) CORT for 21 days, and VOR (days 8-21, 25 mg/kg, ip) or FLX (days 8-21, 15 mg/kg, oral) was additionally administered to the treatment groups. Behavioral tests such as Morris water maze test, novel object recognition test, and object in place test were performed at the end of the dosing schedule to assess cognition. After behavior tests, mice were sacrificed, and hippocampus was separated from brain tissue for reverse transcriptase polymerase chain reaction (RT-PCR), Western blot, and immunohistochemistry studies. VOR treatment attenuated endoplasmic reticulum (ER) stress in CORT mice as evident from the reduction in DNA damage-inducible transcript 3 (Ddit3) (gene encoding CHOP), caspase 12 (Casp12), and calpain-2 (Capn2) mRNA levels, and cleaved caspase 3 (CASP3) protein expression. Bax inhibitor-1 (BI-1) was significantly increased in VOR-treated CORT mice. VOR also reversed CORT induced increase in HDAC2 level in the CA3 region. The protective effects of VOR were comparable to that of FLX in CORT mice. Thus, VOR has the potential to reverse cognitive dysfunction via modulation of ER stress markers and HDAC2.

Assessment of prenatal stress-related cortisol exposure: focus on cortisol accumulation in hair and nails

Prenatal stress adversely affects offspring development. Although cortisol is hypothesized to be a key mediator of stress-induced developmental deficits, determining the amount of fetal cortisol exposure produced by maternal stress has proved challenging. Current approaches, such as measuring cortisol concentrations in maternal plasma, saliva, or urine, amniotic fluid, fetal plasma, or cord blood, all have significant limitations for assessing cumulative fetal cortisol exposure over time. A recently emerging approach is to measure cortisol concentrations in maternal hair and/or newborn hair or nail samples. Maternal hair cortisol potentially shows long-term production across each trimester of pregnancy, whereas neonatal hair or nail cortisol is thought to reflect mainly third trimester hormone accumulation. This review first describes fetal adrenocortical development, placental cortisol metabolism, and the various sources of fetal cortisol exposure across pregnancy. We then summarize the results obtained from "classical" methods of assessing prenatal cortisol exposure prior to the advent of hair and nail cortisol measurement. Lastly, we discuss the initial development and validation of the hair cortisol methodology, its subsequent application to studies of chronic stress, and recent findings regarding maternal and neonatal hair or nail cortisol concentrations in relation to prenatal stress and other variables of interest.

Integrating Autism Spectrum Disorder Pathophysiology: Mitochondria, Vitamin A, CD38, Oxytocin, Serotonin and Melatonergic Alterations in the Placenta and Gut

BACKGROUND

A diverse array of data has been associated with autism spectrum disorder (ASD), reflecting the complexity of its pathophysiology as well as its heterogeneity. Two important hubs have emerged, the placenta/prenatal period and the postnatal gut, with alterations in mitochondria functioning crucial in both.

METHODS

Factors acting to regulate mitochondria functioning in ASD across development are reviewed in this article.

RESULTS

Decreased vitamin A, and its retinoic acid metabolites, lead to a decrease in CD38 and associated changes that underpin a wide array of data on the biological underpinnings of ASD, including decreased oxytocin, with relevance both prenatally and in the gut. Decreased sirtuins, poly-ADP ribose polymerase-driven decreases in nicotinamide adenine dinucleotide (NAD+), hyperserotonemia, decreased monoamine oxidase, alterations in 14-3-3 proteins, microRNA alterations, dysregulated aryl hydrocarbon receptor activity, suboptimal mitochondria functioning, and decreases in the melatonergic pathways are intimately linked to this. Many of the above processes may be modulating, or mediated by, alterations in mitochondria functioning. Other bodies of data associated with ASD may also be incorporated within these basic processes, including how ASD risk factors such as maternal obesity and preeclampsia, as well as more general prenatal stressors, modulate the likelihood of offspring ASD.

CONCLUSION

Such a mitochondria-focussed integrated model of the pathophysiology of ASD has important preventative and treatment implications.

Cellular stress mechanisms of prenatal maternal stress: Heat shock factors and oxidative stress

Development of the brain prenatally is affected by maternal experience and exposure. Prenatal maternal psychological stress changes brain development and results in increased risk for neuropsychiatric disorders. In this review, multiple levels of prenatal stress mechanisms (offspring brain, placenta, and maternal physiology) are discussed and their intersection with cellular stress mechanisms explicated. Heat shock factors and oxidative stress are closely related to each other and converge with the inflammation, hormones, and cellular development that have been more deeply explored as the basis of prenatal stress risk. Increasing evidence implicates cellular stress mechanisms in neuropsychiatric disorders associated with prenatal stress including affective disorders, schizophrenia, and child-onset psychiatric disorders. Heat shock factors and oxidative stress also have links with the mechanisms involved in other kinds of prenatal stress including external exposures such as environmental toxicants and internal disruptions such as preeclampsia. Integrative understanding of developmental neurobiology with these cellular and physiological mechanisms is necessary to reduce risks and promote healthy brain development.

Fetal glucocorticoid receptor (Nr3c1) deficiency alters the landscape of DNA methylation of murine placenta in a sex-dependent manner and is associated to anxiety-like behavior in adulthood

Prenatal stress defines long-term phenotypes through epigenetic programming of the offspring. These effects are potentially mediated by glucocorticoid release and by sex. We hypothesized that the glucocorticoid receptor (Gr, Nr3c1) fashions the DNA methylation profile of offspring. Consistent with this hypothesis, fetal Nr3c1 heterozygosity leads to altered DNA methylation landscape in fetal placenta in a sex-specific manner. There was a significant overlap of differentially methylated genes in fetal placenta and adult frontal cortex in Nr3c1 heterozygotes. Phenotypically, Nr3c1 heterozygotes show significantly more anxiety-like behavior than wildtype. DNA methylation status of fetal placental tissue is significantly correlated with anxiety-like behavior of the same animals in adulthood. Thus, placental DNA methylation might predict behavioral phenotypes in adulthood. Our data supports the hypothesis that Nr3c1 influences DNA methylation at birth and that DNA methylation in placenta correlates with adult frontal cortex DNA methylation and anxiety-like phenotypes.

The Role of 11β-Hydroxy Steroid Dehydrogenase Type 2 in Glucocorticoid Programming of Affective and Cognitive Behaviours

Developmental exposure to stress hormones, i.e. glucocorticoids, is central to the process of prenatal programming of later-life health. Glucocorticoid overexposure, through stress or exogenous glucocorticoids, results in a reduced birthweight, as well as affective and neuropsychiatric outcomes in adults, combined with altered hypothalamus-pituitary-adrenal (HPA) axis activity. As such, glucocorticoids are tightly regulated during development through the presence of the metabolizing enzyme 11β-hydroxysteroid dehydrogenase type 2 (HSD2). HSD2 is highly expressed in 2 hubs during development, i.e. the placenta and the fetus itself, protecting the fetus from inappropriate glucocorticoid exposure early in gestation. Through manipulation of HSD2 expression in the mouse placenta and fetal tissues, we are able to determine the relative contribution of glucocorticoid exposure in each compartment. Feto-placental HSD2 deletion resulted in a reduced birthweight and the development of anxiety- and depression-like behaviours in adult mice. The placenta itself is altered by glucocorticoid overexposure, which causes reduced placental weight and vascular arborisation. Furthermore, altered flow and resistance in the umbilical vessels and modification of fetal heart function and development are observed. However, brain-specific HSD2 removal (HSD2BKO) also generated adult phenotypes of depressive-like behaviour and memory deficits, demonstrating the importance of fetal brain HSD2 expression in development. In this review we will discuss potential mechanisms underpinning early-life programming of adult neuropsychiatric disorders and the novel therapeutic potential of statins.

Alterations of Cortisol Metabolism in Human Disorders

The interconversion of active and inactive corticosteroids - cortisol and cortisone, respectively, in humans - is modulated by isozymes of 11β-hydroxysteroid dehydrogenase (11-HSD). Studies of this process have provided crucial insights into glucocorticoid effects in a wide variety of tissues. The 11-HSD1 isozyme functions mainly as an oxoreductase (cortisone to cortisol) and is expressed at high levels in the liver and other glucocorticoid target tissues. Because it is required for full physiological effects of cortisol, it has emerged as a drug target for metabolic syndrome and type 2 diabetes. Mutations in the corresponding HSD11B1 gene, or in the H6PD gene encoding hexose-6-phosphate dehydrogenase (which supplies the NADPH required for the oxoreductase activity of 11-HSD1), cause apparent cortisone reductase deficiency, a rare syndrome of adrenocortical hyperactivity and hyperandrogenism. In contrast, the 11-HSD2 isozyme functions as a dehydrogenase (cortisol to cortisone) and is expressed mainly in mineralocorticoid target tissues, where it bars access of cortisol to the mineralocorticoid receptor. Mutations in the HSD11B2 gene encoding 11-HSD2 cause the syndrome of apparent mineralocorticoid excess, a severe form of familial hypertension. The role of this enzyme in the pathogenesis of common forms of low-renin hypertension remains uncertain.

Glucocorticoids, antenatal corticosteroid therapy and fetal heart maturation

Glucocorticoids are essential in mammals to mature fetal organs and tissues in order to survive after birth. Hence, antenatal glucocorticoid treatment (termed antenatal corticosteroid therapy) can be life-saving in preterm babies and is commonly used in women at risk of preterm birth. While the effects of glucocorticoids on lung maturation have been well described, the effects on the fetal heart remain less clear. Experiments in mice have shown that endogenous glucocorticoid action is required to mature the fetal heart. However, whether the potent synthetic glucocorticoids used in antenatal corticosteroid therapy have similar maturational effects on the fetal heart is less clear. Moreover, antenatal corticosteroid therapy may increase the risk of cardiovascular disease in adulthood. Here, we present a narrative review of the evidence relating to the effects of antenatal glucocorticoid action on the fetal heart and discuss the implications for antenatal corticosteroid therapy.

11β-Hydroxysteroid Dehydrogenases and Hypertension in the Metabolic Syndrome

The metabolic syndrome describes a clustering of risk factors—visceral obesity, dyslipidaemia, insulin resistance, and salt-sensitive hypertension—that increases mortality related to cardiovascular disease, type 2 diabetes, cancer, and non-alcoholic fatty liver disease. The prevalence of these concurrent comorbidities is ~ 25–30% worldwide, and metabolic syndrome therefore presents a significant global public health burden. Evidence from clinical and preclinical studies indicates that glucocorticoid excess is a key causal feature of metabolic syndrome. This is not increased systemic in circulating cortisol, rather increased bioavailability of active glucocorticoids within tissues. This review examines the role of covert glucocorticoid excess on the hypertension of the metabolic syndrome. Here, the role of the 11β-hydroxysteroid dehydrogenase enzymes, which exert intracrine and paracrine control over glucocorticoid signalling, is examined. 11βHSD1 amplifies glucocorticoid action in cells and contributes to hypertension through direct and indirect effects on the kidney and vasculature. The deactivation of glucocorticoid by 11βHSD2 controls ligand access to glucocorticoid and mineralocorticoid receptors: loss of function promotes salt retention and hypertension. As for hypertension in general, high blood pressure in the metabolic syndrome reflects a complex interaction between multiple systems. The clear association between high dietary salt, glucocorticoid production, and metabolic disorders has major relevance for human health and warrants systematic evaluation.

Diurnal Hypothalamic-Pituitary-Adrenal Axis Measures and Inflammatory Marker Correlates in Major Depressive Disorder

Dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis and inflammatory systems is a consistent finding in patients with Major Depressive Disorder (MDD). Cortisol is often assessed by measurement of the cortisol awakening response (CAR) and/or diurnal cortisol levels. Some methods of cortisol measurement overestimate cortisol concentration due to detection of other glucocorticoids including the relatively inert cortisone, therefore this study aimed to assess the presence of both cortisol and cortisone, and the cortisol-cortisone catalyzing enzyme 11β-hydroxysteroiddehydrogenase type 1 (11β-HSD1), in depressed patients and controls. Because the HPA axis is known to regulate the body’s immune system, relationships between measures of cytokines and cortisol were also assessed. Saliva samples were collected from 57 MDD patients and 40 healthy controls at five post-wakening time points (0, +30, +60, +720 and +750 min). Glucocorticoid concentrations were measured by liquid chromatography mass spectrometry. Whole blood mRNA expression of several inflammatory markers was measured by quantitative polymerase chain reaction. This study replicated the common finding of elevated morning cortisol and reduced CAR reactivity in MDD and found no differences in cortisone or 11β-HSD1 mRNA measures. There was a negative association between interleukin 1-β (IL-1β) mRNA and morning cortisol reactivity within the depressed group, indicating that dysregulation of the HPA axis and immune system may be interconnected.

Design, synthesis and in vivo study of novel pyrrolidine-based 11β-HSD1 inhibitors for age-related cognitive dysfunction

Recent findings suggest that treatment with 11β-HSD1 inhibitors provides a novel approach to deal with age-related cognitive dysfunctions, including Alzheimer's disease. In this work we report potent 11β-HSD1 inhibitors featuring unexplored pyrrolidine-based polycyclic substituents. A selected candidate administered to 12-month-old SAMP8 mice for four weeks prevented memory deficits and displayed a neuroprotective action. This is the first time that 11β-HSD1 inhibitors have been studied in this broadly-used mouse model of accelerated senescence and late-onset Alzheimer's disease.

Glucocorticoids and Reproduction: Traffic Control on the Road to Reproduction

Glucocorticoids are steroid hormones that regulate diverse cellular functions and are essential to facilitate normal physiology. However, stress-induced levels of glucocorticoids result in several pathologies including profound reproductive dysfunction. Compelling new evidence indicates that glucocorticoids are crucial to the establishment and maintenance of reproductive function. The fertility-promoting or -inhibiting activity of glucocorticoids depends on timing, dose, and glucocorticoid responsiveness within a given tissue, which is mediated by the glucocorticoid receptor (GR). The GR gene and protein are subject to cellular processing, contributing to signaling diversity and providing a mechanism by which both physiological and stress-induced levels of glucocorticoids function in a cell-specific manner. Understanding how glucocorticoids regulate fertility and infertility may lead to novel approaches to the regulation of reproductive function.

Local glucocorticoid production in lymphoid organs of mice and birds: Functions in lymphocyte development

Circulating glucocorticoids (GCs) are powerful regulators of immunity. Stress-induced GC secretion by the adrenal glands initially enhances and later suppresses the immune response. GC targets include lymphocytes of the adaptive immune system, which are well known for their sensitivity to GCs. Less appreciated, however, is that GCs are locally produced in lymphoid organs, such as the thymus, where GCs play a critical role in selection of the T cell antigen receptor (TCR) repertoire. Here, we review the roles of systemic and locally-produced GCs in T lymphocyte development, which has been studied primarily in laboratory mice. By antagonizing TCR signaling in developing T cells, thymus-derived GCs promote selection of T cells with stronger TCR signaling. This results in increased T cell-mediated immune responses to a range of antigens. We then compare local and systemic GC patterns in mice to those in several bird species. Taken together, these studies suggest that a combination of adrenal and lymphoid GC production might function to adaptively regulate lymphocyte development and selection, and thus antigen-specific immune reactivity, to optimize survival under different environmental conditions. Future studies should examine how lymphoid GC patterns vary across other vertebrates, how GCs function in B lymphocyte development in the bone marrow, spleen, and the avian bursa of Fabricius, and whether GCs adaptively program immunity in free-living animals.

ISN Forefronts Symposium 2015: The Evolution of Hypertension-Old Genes, New Concepts

Hypertension is known as the “silent killer,” driving the global public health burden of cardiovascular and renal disease. Blood pressure homeostasis is intimately associated with sodium balance and the distribution of sodium between fluid compartments and within tissues. On a population level, most societies consume 10 times more salt that the 0.5 g required by physiological need. This high salt intake is strongly linked to hypertension and to the World Health Organization targeting a ∼30% relative reduction in mean population salt intake to arrest the global mortality due to cardiovascular disease. But how does a habitually high-salt diet cause blood pressure to rise? In this focused review, we discuss 2 “evolutionary medicine” concepts, presented at the ISN Forefront Meeting “Immunomodulation of Cardio-renal Function.” We first examine how ancestral variants in genes that conferred a selection advantage during early human development are now maladaptive. We then discuss the conservation of “renal” sodium transport processes across multiple organ systems, including the brain. These systems influence sodium appetite and can exert an often-overlooked effect on long-term blood pressure control.

Conditional Deletion of Hsd11b2 in the Brain Causes Salt Appetite and Hypertension

Supplemental Digital Content is available in the text.

Background—

The hypertensive syndrome of Apparent Mineralocorticoid Excess is caused by loss-of-function mutations in the gene encoding 11β-hydroxysteroid dehydrogenase type 2 (11βHSD2), allowing inappropriate activation of the mineralocorticoid receptor by endogenous glucocorticoid. Hypertension is attributed to sodium retention in the distal nephron, but 11βHSD2 is also expressed in the brain. However, the central contribution to Apparent Mineralocorticoid Excess and other hypertensive states is often overlooked and is unresolved. We therefore used a Cre-Lox strategy to generate 11βHSD2 brain-specific knockout (Hsd11b2.BKO) mice, measuring blood pressure and salt appetite in adults.

Methods and Results—

Basal blood pressure, electrolytes, and circulating corticosteroids were unaffected in Hsd11b2.BKO mice. When offered saline to drink, Hsd11b2.BKO mice consumed 3 times more sodium than controls and became hypertensive. Salt appetite was inhibited by spironolactone. Control mice fed the same daily sodium intake remained normotensive, showing the intrinsic salt resistance of the background strain. Dexamethasone suppressed endogenous glucocorticoid and abolished the salt-induced blood pressure differential between genotypes. Salt sensitivity in Hsd11b2.BKO mice was not caused by impaired renal sodium excretion or volume expansion; pressor responses to phenylephrine were enhanced and baroreflexes impaired in these animals.

Conclusions—

Reduced 11βHSD2 activity in the brain does not intrinsically cause hypertension, but it promotes a hunger for salt and a transition from salt resistance to salt sensitivity. Our data suggest that 11βHSD2-positive neurons integrate salt appetite and the blood pressure response to dietary sodium through a mineralocorticoid receptor–dependent pathway. Therefore, central mineralocorticoid receptor antagonism could increase compliance to low-sodium regimens and help blood pressure management in cardiovascular disease.