'You can't roll the clock back and reverse the effects of experiences' Bruce McEwen used to say when explaining how allostasis labels the adaptive process. Here we will for once roll the clock back... Show more'You can't roll the clock back and reverse the effects of experiences' Bruce McEwen used to say when explaining how allostasis labels the adaptive process. Here we will for once roll the clock back to the times that the science of the glucocorticoid hormone was honored with a Nobel prize and highlight the discovery of their receptors in the hippocampus as inroad to its current status as master regulator in control of stress coping and adaptation. Glucocorticoids operate in concert with numerous neurotransmitters, neuropeptides, and other hormones with the aim to facilitate processing of information in the neurocircuitry of stress, from anticipation and perception of a novel experience to behavioral adaptation and memory storage. This action, exerted by the glucocorticoids, is guided by two complementary receptor systems, mineralocorticoid receptors (MR) and glucocorticoid receptors (GR), that need to be balanced for a healthy stress response pattern. Here we discuss the cellular, neuroendocrine, and behavioral studies underlying the MR:GR balance concept, highlight the relevance of hypothalamic pituitary-adrenal (HPA)-axis patterns and note the limited understanding yet of sexual dimorphism in glucocorticoid actions. We conclude with the prospect that (i) genetically and epigenetically regulated receptor variants dictate cell-type-specific transcriptome signatures of stress-related neuropsychiatric symptoms and (ii) selective receptor modulators are becoming available for more targeted treatment. These two new developments to 'restart the clock' with the to resilience. Show less
More than 45 years of research on the effects of glucocorticoids on brain function has yielded many insights, but also left a number of longstanding questions. One conundrum has been how activation... Show moreMore than 45 years of research on the effects of glucocorticoids on brain function has yielded many insights, but also left a number of longstanding questions. One conundrum has been how activation of the structurally comparable mineralocorticoid receptor (MR) and glucocorticoid receptor (GR) can lead to very different, or even opposite effects. It also remained unclear how the consequence of activation of a single receptor, GR, can differ from cell to cell and from situation to situation. In this thesis we have investigated two aspects of transcriptional regulation in response to glucocorticoids: the cause of MR/GR specificity, and the role of crosstalk with other transcription factors. Within the hippocampus, we found NeuroD factors to drive the specificity in corticosteroid receptor DNA binding and subsequent gene regulation, i.e. by stimulating MR signaling. We identified Jun dimerization protein 2 (Jdp2) as a stress-responsive MR-specific target gene. In a stress hormone relevant memory task, GR was suggested to act context-dependently and several novel GR target genes were detected. Further elucidation of distinct MR/GR downstream pathways will enable us to better understand the stress physiology and more specifically target aspects of glucocorticoid signaling for treatment of stress-related disorders. Show less
Objective: Carbonyl reductase 1 (Cbr1), a recently discovered contributor to tissue glucocorticoid metabolism converting corticosterone to 2013dihydrocorticosterone (2013-DHB), is upregulated in... Show moreObjective: Carbonyl reductase 1 (Cbr1), a recently discovered contributor to tissue glucocorticoid metabolism converting corticosterone to 2013dihydrocorticosterone (2013-DHB), is upregulated in adipose tissue of obese humans and mice and may contribute to cardiometabolic complications of obesity. This study tested the hypothesis that Cbr1-mediated glucocorticoid metabolism influences glucocorticoid and mineralocorticoid receptor activation in adipose tissue and impacts glucose homeostasis in lean and obese states. Methods: The actions of 2013-DHB on corticosteroid receptors in adipose tissue were investigated first using a combination of in silico, in vitro, and transcriptomic techniques and then in vivo administration in combination with receptor antagonists. Mice lacking one Cbr1 allele and mice overexpressing Cbr1 in their adipose tissue underwent metabolic phenotyping before and after induction of obesity with high-fat feeding. Results: 2013-DHB activated both the glucocorticoid and mineralocorticoid receptor in adipose tissue and systemic administration to wild-type mice induced glucose intolerance, an effect that was ameliorated by both glucocorticoid and mineralocorticoid receptor antagonism. Cbr1 haploinsufficient lean male mice had lower fasting glucose and improved glucose tolerance compared with littermate controls, a difference that was abolished by administration of 2013-DHB and absent in female mice with higher baseline adipose 2013-DHB concentrations than male mice. Conversely, overexpression of Cbr1 in adipose tissue resulted in worsened glucose tolerance and higher fasting glucose in lean male and female mice. However, neither Cbr1 haploinsfficiency nor adipose overexpression affected glucose dyshomeostasis induced by high-fat feeding. Conclusions: Carbonyl reductase 1 is a novel regulator of glucocorticoid and mineralocorticoid receptor activation in adipose tissue that influences glucose homeostasis in lean mice. (c) 2021 The Authors. Published by Elsevier GmbH. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/). Show less
Galbally, M.; Watson, S.J.; IJzendoorn, M. van; Saffery, R.; Ryan, J.; Kloet, E.R. de; ... ; Lewis, A.J. 2020
Understanding fetal programming pathways that underpin the relationship between maternal and offspring mental health necessitates an exploration of potential role of epigenetic variation in early... Show moreUnderstanding fetal programming pathways that underpin the relationship between maternal and offspring mental health necessitates an exploration of potential role of epigenetic variation in early development. Two genes involved in stress response regulation, the glucocorticoid and mineralocorticoid receptors (NR3C1 and NR3C2) have been a focus in understanding stressful exposures and mental health outcomes. Data were obtained from 236 pregnant women from the Mercy Pregnancy Emotional Wellbeing Study (MPEWS), a selected pregnancy cohort, recruited in early pregnancy. Depression was measured using the Structured Clinical Interview for DSM-IV (SCID-IV) and repeated measures of the Edinburgh Postnatal Depression Scale (EPDS). Antidepressant use, stressful events and anxiety symptoms were measured. NR3C1 and NR3C2 DNA methylation was measured in placental and infant buccal samples. Infant cortisol was measured in repeat saliva samples across a task. This study found maternal early pregnancy depressive disorder and symptoms were associated with lower DNA methylation at NR3C2 CpG_24 in placental tissue. There were no significant differences for depression or antidepressant use for DNA methylation of NR3C1. Antenatal depression was associated with lower infant cortisol reactivity at 12 months. DNA methylation in CpG_24 site in NR3C2 in placental samples suppressed the relationship between early maternal depressive symptoms and infant cortisol reactivity. These findings show a relationship between antenatal depression, NR3C2 DNA methylation and infant cortisol response providing support for a specific fetal programming pathway. Further research is required to examine the stability of this epigenetic mark across childhood and long-term mental health outcomes. Show less
Worldwide, raised blood pressure is estimated to affect 35-40% of the adult population and is a main conditioning factor for cardiovascular diseases and stroke. Animal models of hypertension have... Show moreWorldwide, raised blood pressure is estimated to affect 35-40% of the adult population and is a main conditioning factor for cardiovascular diseases and stroke. Animal models of hypertension have provided great advances concerning the pathophysiology of human hypertension, as already shown for the deoxycorticosterone-salt treated rat, the Dahl-salt sensitive rat, the Zucker obese rat and the spontaneously hypertensive rat (SHR). SHR has been widely used to study abnormalities of the brain in chronic hypertension. This review summarises present and past evidence that in the SHR, hypertension causes hippocampal tissue damage which triggers a pro-inflammatory feedforward cascade affecting this vulnerable brain region. The cascade is driven by mineralocorticoid receptor (MR) activation responding to endogenous corticosterone rather than aldosterone. Increased MR expression is a generalised feature of the SHR which seems to support first the rise in blood pressure. Then oxidative stress caused by vasculopathy and hypoxia further increases MR activation in hippocampal neurons and glia cells, activates microglia activation and pro-inflammatory mediators, and down-regulates anti-inflammatory factors. In contrast to MR, involvement of the glucocorticoid receptor (GR) in SHR is less certain. GR showed normal expression levels and blockage with an antagonist failed to reduce blood pressure of SHR. The findings support the concept that MR:GR imbalance caused by vasculopathy causes a switch in MR function towards a proverbial "death" receptor. Show less
Psychotic depression is characterized by elevated circulating cortisol, and high daily doses of the glucocorticoid/progesterone antagonist mifepristone for 1 week are required for significant... Show morePsychotic depression is characterized by elevated circulating cortisol, and high daily doses of the glucocorticoid/progesterone antagonist mifepristone for 1 week are required for significant improvement. Using a rodent model, we find that such high doses of mifepristone are needed because the antagonist is rapidly degraded and poorly penetrates the blood-brain barrier, but seems to facilitate the entry of cortisol. We also report that in male C57BL/6J mice, after a 7-day treatment with a high dose of mifepristone, basal blood corticosterone levels were similar to that of vehicle controls. This is surprising because after the first mifepristone challenge, corticosterone remained elevated for about 16 h, and then decreased towards vehicle control levels at 24 h. At that time, stress-induced corticosterone levels of the 1xMIF were sevenfold higher than the 7xMIF group, the latter response being twofold lower than controls. The 1xMIF mice showed behavioral hyperactivity during exploration of the circular hole board, while the 7xMIF mice rather engaged in serial search patterns. To explain this rapid reset of corticosterone secretion upon recurrent mifepristone administration, we suggest the following: (i) A rebound glucocorticoid feedback after cessation of mifepristone treatment. (ii) Glucocorticoid agonism in transrepression and recruitment of cell-specific coregulator cocktails. (iii) A more prominent role of brain MR function in control of stress circuit activity. An overview table of neuroendocrine MIF effects is provided. The data are of interest for understanding the mechanistic underpinning of stress system reset as treatment strategy for stress-related diseases. Show less
In this thesis I aimed to explore further finesses in the cellular dynamics of the two corticosteroid receptors, the MR and the GR, in both their membrane-associated and their nuclear... Show moreIn this thesis I aimed to explore further finesses in the cellular dynamics of the two corticosteroid receptors, the MR and the GR, in both their membrane-associated and their nuclear subpopulations. Amongst others I quantified the dynamics of the receptors at the membrane (only MR) and at the chromatin Show less
The balance between corticosteroid actions induced via activation of the mineralocorticoid receptor (MR) and the glucocorticoid receptor (GR) determines the brain's response to stress. While both... Show moreThe balance between corticosteroid actions induced via activation of the mineralocorticoid receptor (MR) and the glucocorticoid receptor (GR) determines the brain's response to stress. While both receptors are best known for their delayed genomic role, it has become increasingly evident that they can also associate with the plasma membrane and act as mediators of rapid, nongenomic signalling. Nongenomic corticosteroid actions in the brain are required for the coordination of a rapid adaptive response to stress; membrane-associated MRs and GRs play a major role herein. However, many questions regarding the underlying mechanism are still unresolved. How do MR and GR translocate to the membrane and what are their downstream signalling partners? In this review we discuss these issues based on insights obtained from related receptors, most notably the estrogen receptor alpha. (C) 2011 Elsevier Ireland Ltd. All rights reserved. Show less
Depression involves multiple mental problems, including low mood, inability to experience pleasure and emotional, cognitive and behavioral problems. It has a lifetime prevalence of ~15% in the... Show moreDepression involves multiple mental problems, including low mood, inability to experience pleasure and emotional, cognitive and behavioral problems. It has a lifetime prevalence of ~15% in the Dutch population, striking women twice as often as men. The disorder often comprises persisting disturbances in the neuroendocrine stress system, the hypothalamic- pituitary-adrenal (HPA) axis, including disregulation of its end-hormone cortisol. Cortisol normally stimulates emotional, cognitive and behavioral processes in order to cope with a stressor and promotes recovery, learning and memory. This thesis describes the identification of a specific genetic variant of the mineralocorticoid receptor (MR), one of the two receptors for cortisol, which protects against depression. MR transcript expression was found to be lower in postmortem limbic brain regions of depressed patients compared to non-depressed subjects. In addition, a specific and common MR gene variant was identified that results in higher MR expression in vitro. This same variant was found to associate with personality characteristics that predict the risk of depression later in life and with a lower risk of depression itself. All associations were found only in women and not in men. To conclude, the MR is an important determinant of resilience; increased MR expression seems to be protective against depression. Show less
Pronounced ultradian and circadian rhythms in the hormones of the hypothalamic-pituitary-adrenal (HPA) axis (i.e. glucocorticoids), one of the body__s major neuroendocrine axes, were already... Show morePronounced ultradian and circadian rhythms in the hormones of the hypothalamic-pituitary-adrenal (HPA) axis (i.e. glucocorticoids), one of the body__s major neuroendocrine axes, were already demonstrated several decades ago. Until now, the clinical relevance of the pulsatile nature of glucocorticoids was poorly understood or sometimes even regarded as not important. Its evolutionary conservation across many species however implies biological significance. Indeed, glucocorticoids have been proven to be crucial for a plethora of bodily functions, e.g. emotion, cognition and the central mechanism underlying the adaptation to stress. Furthermore, disturbances in the characteristic temporal pattern of glucocorticoid exposure have often been described in stress-related pathology. However, the significance of glucocorticoids secretory patterns for physiology, stress responsiveness and nuclear receptor signalling is still largely unexplored and is accordingly addressed in this thesis. A new concept in the endocrinology of glucocorticoids has evolved from the data presented here showing that pulsatile release of glucocorticoids is a major determinant in __resilience__ of glucocorticoid signalling in neuronal cells and stress responsiveness. Moreover, we show that particularly the glucocorticoid receptor is affected after disrupting glucocorticoid pulsatility and could thus provide an excellent target for therapy to normalise the downstream effects of disturbances in glucocorticoid rhythms in stress-related disease. Show less
