Stress and the adrenocortical control of epinephrine synthesis

The synchronic, diachronic cell as the holism of consciousness

The cell is both synchronic and diachronic, based on ontogeny and phylogeny, respectively. As experimental evidence for this holism, absent gravitational force, differentiated lung and bone cells devolve, losing their phenotypes, losing their evolutionary status, reverting to their nonlocal status. Thus, when evolution is seen as serial homeostasis, it is homologous with Quantum Entanglement as the nonlocal means of maintaining homeostatic balance between particles. This monadic perspective on consciousness is one-hundred and eighty degrees out of synch with the conventional way of thinking about consciousness as a diad, or mind and brain. There have been many attempts to explain consciousness, virtually all of them based on the brain as mind. The working hypothesis is that consciousness is a holism constituted by the unicell, the lipid cell membrane forming a barrier between inside and outside of the cell's environment as a topology. Conceptually, both the unicell and 'two hands clapping' are holisms, but because the cell is constituted by the ambiguity of negative entropy, and 'one hand clapping' requires two hands, they are both pseudo-holisms, constantly striving to be whole again. In the case of the cell, it is incomplete in the sense that there are factors in the ever-changing environment that can homeostatically complete it. That process results in biochemical modification of specific DNA codes in the egg or sperm so that the offspring is able to adapt in subsequent generations epigenetically. The opportunity to trace the evolution of the breath from humans to fish opens up to the further revelation of the interplay between evolution and geological change, tracing it back to invertebrates, sponges, and ultimately to unicellular organisms. And therein is evidence that the Cosmos itself 'breathes', providing the ultimate celestial fundament for this trail of holisms.

Validity of mental and physical stress models

Different stress models are employed to enhance our understanding of the underlying mechanisms and explore potential interventions. However, the utility of these models remains a critical concern, as their validities may be limited by the complexity of stress processes. Literature review revealed that both mental and physical stress models possess reasonable construct and criterion validities, respectively reflected in psychometrically assessed stress ratings and in activation of the sympathoadrenal system and the hypothalamic-pituitary-adrenal axis. The findings are less robust, though, in the pharmacological perturbations' domain, including such agents as adenosine or dobutamine. Likewise, stress models' convergent- and discriminant validity vary depending on the stressors' nature. Stress models share similarities, but also have important differences regarding their validities. Specific traits defined by the nature of the stressor stimulus should be taken into consideration when selecting stress models. Doing so can personalize prevention and treatment of stress-related antecedents, its acute processing, and chronic sequelae. Further work is warranted to refine stress models' validity and customize them so they commensurate diverse populations and circumstances.

The holism of evolution as consciousness

Quantum Entanglement has been hypothesized to mediate non-local consciousness, underlying which, empirically, is the force of gravity. Upon further reflection, the case can be made for 'the breath' as the physiologic trait that binds all of these properties together, offering further opportunity for hypothesis testing experimentation. Humans have inexplicably made extraordinary intellectual and technical advances within a relatively very short period of time, referred to as the 'great leap forward'. It would be of great value if we could identify how and why we have evolved so rapidly. There is a holotropism that begins with the Big Bang that is centered on the homeostatic control of energy, perpetually referencing the First Principles of Physiology. "The Breath" is how and why our physiology has managed to perpetuate our species, and perhaps why the lung has been 'over-engineered' in order to facilitate the role of breathing in consciousness.

Mutual Effects of Orexin and Bone Morphogenetic Proteins on Catecholamine Regulation Using Adrenomedullary Cells

Orexins are neuronal peptides that play a prominent role in sleep behavior and feeding behavior in the central nervous system, though their receptors also exist in peripheral organs, including the adrenal gland. In this study, the effects of orexins on catecholamine synthesis in the rat adrenomedullary cell line PC12 were investigated by focusing on their interaction with the adrenomedullary bone morphogenetic protein (BMP)-4. Orexin A treatment reduced the mRNA levels of key enzymes for catecholamine synthesis, including tyrosine hydroxylase (Th), 3,4-dihydroxyphenylalanie decarboxylase (Ddc) and dopamine β-hydroxylase (Dbh), in a concentration-dependent manner. On the other hand, treatment with BMP-4 suppressed the expression of Th and Ddc but enhanced that of Dbh with or without co-treatment with orexin A. Of note, orexin A augmented BMP-receptor signaling detected by the phosphorylation of Smad1/5/9 through the suppression of inhibitory Smad6/7 and the upregulation of BMP type-II receptor (BMPRII). Furthermore, treatment with BMP-4 upregulated the mRNA levels of OX1R in PC12 cells. Collectively, the results indicate that orexin and BMP-4 suppress adrenomedullary catecholamine synthesis by mutually upregulating the pathway of each other in adrenomedullary cells.

Adaptive remodeling of the stimulus-secretion coupling: Lessons from the 'stressed' adrenal medulla

Stress is part of our daily lives and good health in the modern world is offset by unhealthy lifestyle factors, including the deleterious consequences of stress and associated pathologies. Repeated and/or prolonged stress may disrupt the body homeostasis and thus threatens our lives. Adaptive processes that allow the organism to adapt to new environmental conditions and maintain its homeostasis are therefore crucial. The adrenal glands are major endocrine/neuroendocrine organs involved in the adaptive response of the body facing stressful situations. Upon stress episodes and in response to activation of the sympathetic nervous system, the first adrenal cells to be activated are the neuroendocrine chromaffin cells located in the medullary tissue of the adrenal gland. By releasing catecholamines (mainly epinephrine and to a lesser extent norepinephrine), adrenal chromaffin cells actively contribute to the development of adaptive mechanisms, in particular targeting the cardiovascular system and leading to appropriate adjustments of blood pressure and heart rate, as well as energy metabolism. Specifically, this chapter covers the current knowledge as to how the adrenal medullary tissue remodels in response to stress episodes, with special attention paid to chromaffin cell stimulus-secretion coupling. Adrenal stimulus-secretion coupling encompasses various elements taking place at both the molecular/cellular and tissular levels. Here, I focus on stress-driven changes in catecholamine biosynthesis, chromaffin cell excitability, synaptic neurotransmission and gap junctional communication. These signaling pathways undergo a collective and finely-tuned remodeling, contributing to appropriate catecholamine secretion and maintenance of body homeostasis in response to stress.

Plasma-Metanephrines in Patients with Autoimmune Addison's Disease with and without Residual Adrenocortical Function

PURPOSE

Residual adrenocortical function, RAF, has recently been demonstrated in one-third of patients with autoimmune Addison's disease (AAD). Here, we set out to explore any influence of RAF on the levels of plasma metanephrines and any changes following stimulation with cosyntropin.

METHODS

We included 50 patients with verified RAF and 20 patients without RAF who served as controls upon cosyntropin stimulation testing. The patients had abstained from glucocorticoid and fludrocortisone replacement > 18 and 24 h, respectively, prior to morning blood sampling. The samples were obtained before and 30 and 60 min after cosyntropin stimulation and analyzed for serum cortisol, plasma metanephrine (MN), and normetanephrine (NMN) by liquid-chromatography tandem-mass pectrometry (LC-MS/MS).

RESULTS

Among the 70 patients with AAD, MN was detectable in 33%, 25%, and 26% at baseline, 30 min, and 60 min after cosyntropin stimulation, respectively. Patients with RAF were more likely to have detectable MN at baseline (p = 0.035) and at the time of 60 min (p = 0.048) compared to patients without RAF. There was a positive correlation between detectable MN and the level of cortisol at all time points (p = 0.02, p = 0.04, p < 0.001). No difference was noted for NMN levels, which remained within the normal reference ranges.

CONCLUSION

Even very small amounts of endogenous cortisol production affect MN levels in patients with AAD.

Mitochondrial and metabolic features of salugenesis and the healing cycle

Pathogenesis and salugenesis are the first and second stages of the two-stage problem of disease production and health recovery. Salugenesis is the automatic, evolutionarily conserved, ontogenetic sequence of molecular, cellular, organ system, and behavioral changes that is used by living systems to heal. It is a whole-body process that begins with mitochondria and the cell. The stages of salugenesis define a circle that is energy- and resource-consuming, genetically programmed, and environmentally responsive. Energy and metabolic resources are provided by mitochondrial and metabolic transformations that drive the cell danger response (CDR) and create the three phases of the healing cycle: Phase 1-Inflammation, Phase 2-Proliferation, and Phase 3-Differentiation. Each phase requires a different mitochondrial phenotype. Without different mitochondria there can be no healing. The rise and fall of extracellular ATP (eATP) signaling is a key driver of the mitochondrial and metabolic reprogramming required to progress through the healing cycle. Sphingolipid and cholesterol-enriched membrane lipid rafts act as rheostats for tuning cellular sensitivity to purinergic signaling. Abnormal persistence of any phase of the CDR inhibits the healing cycle, creates dysfunctional cellular mosaics, causes the symptoms of chronic disease, and accelerates the process of aging. New research reframes the rising tide of chronic disease around the world as a systems problem caused by the combined action of pathogenic triggers and anthropogenic factors that interfere with the mitochondrial functions needed for healing. Once chronic pain, disability, or disease is established, salugenesis-based therapies will start where pathogenesis-based therapies end.

Hypoxia Differentially Affects Healthy Men and Women During a Daytime Nap With a Dose-Response Relationship: a Randomized, Cross-Over Pilot Study

Context: The use of daytime napping as a countermeasure in sleep disturbances has been recommended but its physiological evaluation at high altitude is limited. Objective: To evaluate the neuroendocrine response to hypoxic stress during a daytime nap and its cognitive impact. Design, Subject, and Setting: Randomized, single-blind, three period cross-over pilot study conducted with 15 healthy lowlander subjects (8 women) with a mean (SD) age of 29(6) years (Clinicaltrials identifier: NCT04146857, https://clinicaltrials.gov/ct2/show/NCT04146857?cond=napping&draw=3&rank=12). Interventions: Volunteers underwent a polysomnography, hematological and cognitive evaluation around a 90 min midday nap, being allocated to a randomized sequence of three conditions: normobaric normoxia (NN), normobaric hypoxia at FiO2 14.7% (NH15) and 12.5% (NH13), with a washout period of 1 week between conditions. Results: Primary outcome was the interbeat period measured by the RR interval with electrocardiogram. Compared to normobaric normoxia, RR during napping was shortened by 57 and 206 ms under NH15 and NH13 conditions, respectively (p < 0.001). Sympathetic predominance was evident by heart rate variability analysis and increased epinephrine levels. Concomitantly, there were significant changes in endocrine parameters such as erythropoietin (∼6 UI/L) and cortisol (∼100 nmol/L) (NH13 vs. NN, p < 0.001). Cognitive evaluation revealed changes in the color-word Stroop test. Additionally, although sleep efficiency was preserved, polysomnography showed lesser deep sleep and REM sleep, and periodic breathing, predominantly in men. Conclusion: Although napping in simulated altitude does not appear to significantly affect cognitive performance, sex-dependent changes in cardiac autonomic modulation and respiratory pattern should be considered before napping is prescribed as a countermeasure.

Non-Canonical Effects of ACTH: Insights Into Adrenal Insufficiency

Introduction

Adrenocorticotropic hormone (ACTH) is produced from proopiomelanocortin, which is predominantly synthetized in the corticotroph and melanotroph cells of the anterior and intermediate lobes of the pituitary gland and the arcuate nucleus of the hypothalamus. Although ACTH clearly has an effect on adrenal homeostasis and maintenance of steroid hormone production, it also has extra-adrenal effects that require further elucidation.

Methods

We comprehensively reviewed English language articles, regardless of whether they reported the presence or absence of adrenal and extra-adrenal ACTH effects.

Results

In the present review, we provide an overview on the current knowledge on adrenal and extra-adrenal effects of ACTH. In the section on adrenal ACTH effects, we focused on corticosteroid rhythmicity and effects on steroidogenesis, mineralocorticoids and adrenal growth. In the section on extra-adrenal effects, we have analyzed the effects of ACTH on the osteoarticular and reproductive systems, adipocytes, immune system, brain and skin. Finally, we focused on adrenal insufficiency.

Conclusions

The role of ACTH in maintaining the function of the hypothalamic-pituitary-adrenal axis is well known. Conversely, if we broaden our vision and analyze its role as a potential treatment strategy in other conditions, it will be evident in the literature that researchers seem to have abandoned this aspect in studies conducted several years ago. We believe it is worth re-evaluating the role of ACTH considering its noncanonical effects on the adrenal gland itself and on extra-adrenal organs and tissues; however, this would not have been possible without the recent advances in the pertinent technologies.

Particulate matter air pollutants and cardiovascular disease: Strategies for intervention

Air pollution is consistently linked with elevations in cardiovascular disease (CVD) and CVD-related mortality. Particulate matter (PM) is a critical factor in air pollution-associated CVD. PM forms in the air during the combustion of fuels as solid particles and liquid droplets and the sources of airborne PM range from dust and dirt to soot and smoke. The health impacts of PM inhalation are well documented. In the US, where CVD is already the leading cause of death, it is estimated that PM2.5 (PM < 2.5 μm in size) is responsible for nearly 200,000 premature deaths annually. Despite the public health data, definitive mechanisms underlying PM-associated CVD are elusive. However, evidence to-date implicates mechanisms involving oxidative stress, inflammation, metabolic dysfunction and dyslipidemia, contributing to vascular dysfunction and atherosclerosis, along with autonomic dysfunction and hypertension. For the benefit of susceptible individuals and individuals who live in areas where PM levels exceed the National Ambient Air Quality Standard, interventional strategies for mitigating PM-associated CVD are necessary. This review will highlight current state of knowledge with respect to mechanisms for PM-dependent CVD. Based upon these mechanisms, strategies for intervention will be outlined. Citing data from animal models and human subjects, these highlighted strategies include: 1) antioxidants, such as vitamins E and C, carnosine, sulforaphane and resveratrol, to reduce oxidative stress and systemic inflammation; 2) omega-3 fatty acids, to inhibit inflammation and autonomic dysfunction; 3) statins, to decrease cholesterol accumulation and inflammation; 4) melatonin, to regulate the immune-pineal axis and 5) metformin, to address PM-associated metabolic dysfunction. Each of these will be discussed with respect to its potential role in limiting PM-associated CVD.

Natural Killer Cell Mobilization in Breast and Prostate Cancer Survivors: The Implications of Altered Stress Hormones Following Acute Exercise

Natural killer (NK) cells from the innate immune system are integral to overall immunity and also in managing the tumor burden during cancer. Breast (BCa) and prostate cancer (PCa) are the most common tumors in U.S. adults. Both BCa and PCa are frequently treated with hormone suppression therapies that are associated with numerous adverse effects including direct effects on the immune system. Regular exercise is recommended for cancer survivors to reduce side effects and improve quality of life. Acute exercise is a potent stimulus for NK cells in healthy individuals with current evidence indicating that NK mobilization in individuals with BCa and PCa is comparable. NK cell mobilization results from elevations in shear stress and catecholamine levels. Despite a normal NK cell response to exercise, increases in epinephrine are attenuated in BCa and PCa. The significance of this potential discrepancy still needs to be determined. However, alterations in adrenal hormone signaling are hypothesized to be due to chronic stress during cancer treatment. Additional compensatory factors induced by exercise are reviewed along with recommendations on standardized approaches to be used in exercise immunology studies involving oncology populations.

Differences in morphology and in composition and release of parotoid gland secretion in introduced cane toads (Rhinella marina) from established populations in Florida, USA

Cane toads are highly toxic bufonids invasive in several locations throughout the world. Although physiological changes and effects on native predators for Australian populations have been well documented, Florida populations have received little attention. Cane toads were collected from populations spanning the invaded range in Florida to assess relative toxicity, through measuring morphological changes to parotoid glands, likelihood of secretion, and the marinobufagenin (MBG) content of secretion. We found that residual body indices increased in individuals from higher latitude populations, and relative parotoid gland size increased with increasing toad size. There was no effect of latitude on the allometric relationship between gland size and toad size. We observed an increase in likelihood of secretion by cane toads in the field with increasing latitude. Individuals from southern and northern populations did not vary significantly in the quantity of MBG contained in their secretion. Laboratory-acclimated cane toads receiving injections of epinephrine were more likely to secrete poison with increasing dose, although there was no difference in likelihood of secretion between southern and northern populations. This suggests that differences between populations in the quantities of epinephrine released in the field, due to altered hypothalamic sensitivity upon disturbance, may be responsible for the latitudinal effects on poison secretion. Our results suggest that altered pressures from northward establishment in Florida have affected sympathetic sensitivity and defensive mechanisms of cane toads, potentially affecting risk to native predators.

Decrease in Salivary Serotonin in Response to Probiotic Supplementation With Saccharomyces boulardii in Healthy Volunteers Under Psychological Stress: Secondary Analysis of a Randomized, Double-Blind, Placebo-Controlled Trial

BACKGROUND

Bacterial probiotics are thought to exert a serotonergic effect relevant to their potential antidepressant and pro-cognitive action, but yeast probiotics have not been tested. The aim of the present study was to determine whether 30-day supplementation with Saccharomyces boulardii affects the level of salivary serotonin under psychological stress and identify the factors associated with it.

METHODS

Healthy medical students were randomized to ingest Saccharomyces boulardii CNCM I-1079 or placebo before a stressful event. Salivary serotonin concentration was assessed before and at the end of supplementation. Moreover, obtained results were compared to psychological, biochemical, physiological and sociodemographic study participants data.

RESULTS

Data of thirty-two participants (22.8 ± 1.7 years of age, 16 males) was available for the main analysis. Supplementation with Saccharomyces boulardii decreased salivary serotonin concentration under psychological stress by 3.13 (95% CI 0.20 to 6.07) ng/mL, p = 0.037, as compared to placebo. Salivary serotonin was positively correlated with salivary metanephrine (β = 0.27, 95% CI 0.02 to 0.52, p = 0.031) and pulse rate (β = 0.28, 95% CI 0.05 to 0.50, p = 0.018), but insignificantly with anxiety, depression, eating attitudes and information retrieval.

CONCLUSIONS

Saccharomyces boulardii CNCM I-1079 may be distinct from bacterial probiotics in its salivary serotonergic effect, which appears positively linked to symapathoadrenal markers. The study requires cautious interpretation, and further investigation.

Adrenal gland response to endocrine disrupting chemicals in fishes, amphibians and reptiles: A comparative overview

The adrenal gland is an essential component of the body stress response; it is formed by two portions: a steroidogenic and a chromaffin tissue. Despite the anatomy of adrenal gland is different among classes of vertebrates, the hormones produced are almost the same. During stress, these hormones contribute to body homeostasis and maintenance of ion balance. The adrenal gland is very sensitive to toxic compounds, many of which behave like endocrine-disruptor chemicals (EDCs). They contribute to alter the endocrine system in wildlife and humans and are considered as possible responsible of the decline of several vertebrate ectotherms. Considering that EDCs regularly can be found in all environmental matrices, the aim of this review is to collect information about the impact of these chemical compounds on the adrenal gland of fishes, amphibians and reptiles. In particular, this review shows the different behavior of these "sentinel species" when they are exposed to stress condition. The data supplied in this review can help to further elucidate the role of EDCs and their harmful impact on the survival of these vertebrates.

Effect of Supplementation with Saccharomyces Boulardii on Academic Examination Performance and Related Stress in Healthy Medical Students: A Randomized, Double-Blind, Placebo-Controlled Trial

In recent years, bacterial probiotic dietary supplementation has emerged as a promising way to improve cognition and to alleviate stress and anxiety; however, yeast probiotics have not been tested. The aim of the present study was to determine whether 30-day supplementation with Saccharomyces boulardii enhances academic performance under stress and affects stress markers. The trial was retrospectively registered at clinicaltrials.gov (NCT03427515). Healthy medical students were randomized to supplement their diet with Saccharomyces boulardii CNCM I-1079 or placebo before sitting for an academic examination, which served as a model of stress. The grades of a final examination adjusted to subject knowledge tested in non-stressful conditions was used as a primary outcome measure. Psychometrically evaluated state anxiety, cortisol and metanephrine salivary levels, and pulse rate were tested at a non-stressful time point before the intervention as well as just before the stressor. Fifty enrolled participants (22.6 ± 1.4 years of age, 19 males) completed the trial in the Saccharomyces and placebo arms. Supplementation with Saccharomyces did not significantly modify examination performance or increase in state anxiety, salivary cortisol, and metanephrine. However, the intervention resulted in higher increase in pulse rate under stress as compared to placebo by 10.4 (95% CI 4.2–16.6) min⁻¹ (p = 0.0018), and the effect positively correlated with increase in salivary metanephrine (Pearson’s r = 0.35, 95% CI 0.09–0.58, p = 0.012). An intention-to-treat analysis was in line with the per-protocol one. In conclusion, supplementation with Saccharomyces boulardii CNCM I-1079 appears largely ineffective in improving academic performance under stress and in alleviating some stress markers, but it seems to increase pulse rate under stress, which may hypothetically reflect enhanced sympathoadrenal activity.

Norepinephrine-stimulated HSCs secrete sFRP1 to promote HCC progression following chronic stress via augmentation of a Wnt16B/β-catenin positive feedback loop

Background

Sustained adrenergic signaling secondary to chronic stress promotes cancer progression; however, the underlying mechanisms for this phenomenon remain unclear. Hepatocellular carcinoma (HCC) frequently develops within fibrotic livers rich in activated hepatic stellate cells (HSCs). Here, we examined whether the stress hormone norepinephrine (NE) could accelerate HCC progression by modulating HSCs activities.

Methods

HCC cells were exposed to conditioned medium (CM) from NE-stimulated HSCs. The changes in cell migration and invasion, epithelial-mesenchymal transition, parameters of cell proliferation, and levels of cancer stem cell markers were analyzed. Moreover, the in vivo tumor progression of HCC cells inoculated with HSCs was studied in nude mice subjected to chronic restraint stress.

Results

CM from NE-treated HSCs significantly promoted cell migration and invasion, epithelial-mesenchymal transition (EMT), and expression of cell proliferation-related genes and cancer stem cell markers in HCC cells. These pro-tumoral effects were markedly reduced by depleting secreted frizzled related protein 1 (sFRP1) in CM. The pro-tumoral functions of sFRP1 were dependent on β-catenin activation, and sFRP1 augmented the binding of Wnt16B to its receptor FZD7, resulting in enhanced β-catenin activity. Additionally, sFRP1 enhanced Wnt16B expression, reinforcing an autocrine feedback loop of Wnt16B/β-catenin signaling. The expression of sFRP1 in HSCs promoted HCC progression in an in vivo model under chronic restraint stress, which was largely attenuated by sFRP1 knockdown.

Conclusions

We identify a new mechanism by which chronic stress promotes HCC progression. In this model, NE activates HSCs to secrete sFRP1, which cooperates with a Wnt16B/β-catenin positive feedback loop. Our findings have therapeutic implications for the treatment of chronic stress-promoted HCC progression.

Cardiac vagal tone, plasma cortisol, and dehydroepiandrosterone response to an ACTH challenge in lame and nonlame dairy cows

We studied the adrenocortical and vagal tone responses to a single ACTH challenge in lame (n = 9) vs nonlame (n = 9) dairy cows. Cows were paired according to parity, days in milk, and milk yield. Plasma cortisol and dehydroepiandrosterone concentrations and cardiac vagal tone response (high-frequency component of heart rate variability) were compared after intravenous ACTH administration. Baseline, minimum or maximum, amplitude of the response and area under the response curve were compared. No difference was detected between groups in the cortisol response. Dehydroepiandrosterone was irresponsive to ACTH treatment, and concentrations did not differ between lame and nonlame cows. Vagal tone decreased in response to the ACTH treatment. High frequency component of heart rate variability was lower in the lame group at all sampling times. Lameness was associated with delayed return to baseline. We concluded that the adrenal response capacity is not influenced by lameness, which supports the concept of lameness being a chronic intermittent rather than a chronically persistent stressor. Dehydroepiandrosterone concentrations were not proven to be useful indicators of hypothalamus-pituitary axis dysfunction in cattle. A decreased vagal contribution to heart rate variability-possibly coupled with increased sympathetic modulation-was observed in lame cows, which suggests that lameness affects the mechanisms underlying the action of ACTH on cardiovascular activity.

Central NPY-Y5 sub-receptor partially functions as a mediator of NPY-induced hypothermia and affords thermotolerance in heat-exposed fasted chicks

Exposure of chicks to a high ambient temperature (HT) has previously been shown to increase neuropeptide Y (NPY) mRNA expression in the brain. Furthermore, it was found that NPY has anti‐stress functions in heat‐exposed fasted chicks. The aim of the study was to reveal the role of central administration of NPY on thermotolerance ability and the induction of heat‐shock protein (HSP) and NPY sub‐receptors (NPYSRs) in fasted chicks with the contribution of plasma metabolite changes. Six‐ or seven‐day‐old chicks were centrally injected with 0 or 375 pmol of NPY and exposed to either HT (35 ± 1°C) or control thermoneutral temperature (CT: 30 ± 1°C) for 60 min while fasted. NPY reduced body temperature under both CT and HT. NPY enhanced the brain mRNA expression of HSP‐70 and ‐90, as well as of NPYSRs‐Y5, ‐Y6, and ‐Y7, but not ‐Y1, ‐Y2, and ‐Y4, under CT and HT. A coinjection of an NPYSR‐Y5 antagonist (CGP71683) and NPY (375 pmol) attenuated the NPY‐induced hypothermia. Furthermore, central NPY decreased plasma glucose and triacylglycerol under CT and HT and kept plasma corticosterone and epinephrine lower under HT. NPY increased plasma taurine and anserine concentrations. In conclusion, brain NPYSR‐Y5 partially afforded protective thermotolerance in heat‐exposed fasted chicks. The NPY‐mediated reduction in plasma glucose and stress hormone levels and the increase in free amino acids in plasma further suggest that NPY might potentially play a role in minimizing heat stress in fasted chicks.

Relationship between sympathoadrenal and pituitary-adrenal response during colorectal distention in the presence of corticotropin-releasing hormone in patients with irritable bowel syndrome and healthy controls

Corticotropin-releasing hormone (CRH) mediates stress responses in the brain-gut axis. Administration of CRH modulates brain activation, for example by controlling the autonomic nervous system in response to colorectal distention. Here, we investigated the relationship between sympathoadrenal and hypothalamic-pituitary-adrenal (HPA) responses to colorectal distention in patients with irritable bowel syndrome (IBS). We enrolled 32 patients with IBS (16 women and 16 men) and 32 healthy subjects (16 women and 16 men), and randomly divided them between CRH and saline injection groups. The patients randomly underwent no (0 mmHg), mild (20 mmHg), or strong (40 mmHg) colorectal distension. CRH (2 μg/kg) or saline was then administered via injection, and the distention protocol was repeated. The heart rate (HR) and HR variability (HRV; calculated as the low [LF] to high frequency [HF] peak ratio, LF/HF) were analyzed using electrocardiography. Plasma noradrenaline, adrenaline, adrenocorticotropic hormone (ACTH), and cortisol levels were measured at the time of each distention. Plasma adrenaline levels were shown to be associated with plasma ACTH levels in HCs injected with CRH during distention using structural equation modeling analysis. Patients with IBS injected with placebo during distention displayed a closer association between these two parameters than those injected with CRH. Generalized estimating equation analysis revealed a significant distention × group × drug interaction for HF power. Moreover, there was a strong correlation between adrenaline and HRV upon CRH injection in controls, but not patients with IBS. The relationship between HPA-sympathoadrenal responses and CRH levels during colorectal distention differs between patients with IBS and controls. Modulation of adrenal gland activity in response to ACTH stimulation may contribute to the brain-gut pathophysiology characteristic of IBS.

Inflammatory Signaling in Hypertension: Regulation of Adrenal Catecholamine Biosynthesis

The immune system is increasingly recognized for its role in the genesis and progression of hypertension. The adrenal gland is a major site that coordinates the stress response via the hypothalamic-pituitary-adrenal axis and the sympathetic-adrenal system. Catecholamines released from the adrenal medulla function in the neuro-hormonal regulation of blood pressure and have a well-established link to hypertension. The immune system has an active role in the progression of hypertension and cytokines are powerful modulators of adrenal cell function. Adrenal medullary cells integrate neural, hormonal, and immune signals. Changes in adrenal cytokines during the progression of hypertension may promote blood pressure elevation by influencing catecholamine biosynthesis. This review highlights the potential interactions of cytokine signaling networks with those of catecholamine biosynthesis within the adrenal, and discusses the role of cytokines in the coordination of blood pressure regulation and the stress response.

Melatonin Elicits Stimulatory Action on the Adrenal Gland of Soay Ram: Morphometrical, Immunohistochemical, and Ultrastructural Study

Endogenous melatonin is a hormone secreted by pineal gland; it has several roles in metabolism, reproduction, and remarkable antioxidant properties. Studies on the melatonin effect on the adrenal glands which are important endocrine organs, controlling essential physiological functions, are still deficient. In this study, we attempted to investigate the effect of exogenous melatonin treatment on the adrenal cortex and medulla using several approaches. Adrenal glands of 15 Soay ram were examined to detect the effect of melatonin treatment. Our results revealed that the cells of adrenal cortex of the treated animals were separated by wide and numerous blood sinusoids and showed signs of increase steroidogenic activity, which are evidenced by functional hypertrophy with increase profiles of mitochondria, smooth endoplasmic reticulum, and lipid droplets. The most striking ultrastructural features in the medulla of the treated group were the engorgement of chromaffin cells with enlarged secretory granules enclosed within a significantly increased diameter of these cells. The cytoplasm of these cells showed numerous mitochondria, rough endoplasmic reticulum (rER), Golgi apparatus, lysosomes, and glycogen granules. Exocytosis of secretory granules to the lumen of blood vessels was evident in the treated group. Piecemeal degranulation mode of secretion was recorded after melatonin treatment. Chromaffin cells in the control group expressed moderate immunoreactivity to Synaptophysin and tyrosine hydroxylase, compared with intensified expression after melatonin treatment. The ganglion cells of the melatonin-treated group showed a significant increase in diameter with numerous rER. The most interesting feature in this study is the presence of small granule chromaffin cells (SGC) and telocytes (TCs) for the first time in the adrenal glands of sheep. Moreover, these SGC cells, Schwann cells, fibroblasts, and progenitor stem cells showed a stimulatory response. The TCs were small branched cells scattered in the adrenal glands around cortical cells, chromaffin cells, nerve fibers, and blood vessels. These cells increased significantly in number, length of their telopodes, and secretory activity after melatonin treatment. In addition, multiple profiles of unmyelinated nerve fibers were demonstrated in all treated specimens. These results indicated that melatonin treatment caused a stimulatory action on all cellular and neuronal elements of the adrenal gland. This study may act as a new direction for treatment of adrenal insufficiency.

Direct effect of hypothalamic neuropeptides on the release of catecholamines by adrenal medulla in sheep - study ex vivo

Stress causes the activation of both the hypothalamic-pituitary-adrenocortical axis and sympatho-adrenal system, thus leading to the release from the adrenal medulla of catecholamines: adrenaline and, to a lesser degree, noradrenaline. It has been established that in addition to catecholamines, the adrenomedullary cells produce a variety of neuropeptides, including corticoliberine (CRH), vasopressin (AVP), oxytocin (OXY) and proopiomelanocortine (POMC) - a precursor of the adrenocorticotropic hormone (ACTH). The aim of this study was to investigate adrenal medulla activity in vitro depending, on a dose of CRH, AVP and OXY on adrenaline and noradrenaline release. Pieces of sheep adrenal medulla tissue (about 50 mg) were put on 24-well plates and were incubated in 1 mL of Eagle medium without hormone (control) or supplemented only once with CRH, AVP and OXY in three doses (10-7, 10-8 and 10-9 M) in a volume of 10 μL. The results showed that CRH stimulates adrenaline and noradrenaline release from the adrenal medulla tissue. The stimulating influence of AVP on adrenaline release was visible after the application of the two lower doses of this neuropeptide; however, AVP reduced noradrenaline release from the adrenal medulla tissue. A strong, inhibitory OXY effect on catecholamine release was observed, regardless of the dose of this hormone. Our results indicate the important role of OXY in the inhibition of adrenal gland activity and thus a better adaptation to stress on the adrenal gland level.

Effect of Prenatal and Postnatal Exposure to Low Doses of DDT on Catecholamine Secretion in Rats in Different Period of Ontogeny

We studied the effects of prenatal and postnatal exposure to low doses of DDT on secretion of basic catecholamines epinephrine and norepinephrine in pubertal and adult rats. It was found that the endocrine-disrupting chemical under study led to a progressive decrease in the content of epinephrine and especially norepinephrine in systemic circulation, which indicated their disturbed secretion by the adrenal medulla and sympathetic nervous system cells. In animals exposed to low doses of DDT in both pre- and postnatal periods, the decrease in catecholamine secretion after puberty was less pronounced than in animals exposed only during the postnatal period, which can indicate the development of compensatory processes.

Particulate Matter Exposure and Stress Hormone Levels

Background:

Exposure to ambient particulate matter (PM) is associated with a number of adverse health outcomes, but potential mechanisms are largely unknown. Metabolomics represents a powerful approach to study global metabolic changes in response to environmental exposures. We therefore conducted this study to investigate changes in serum metabolites in response to the reduction of PM exposure among healthy college students.

Methods:

We conducted a randomized, double-blind crossover trial in 55 healthy college students in Shanghai, China. Real and sham air purifiers were placed in participants’ dormitories in random order for 9 days with a 12-day washout period. Serum metabolites were quantified by using gas chromatography-mass spectrometry and ultrahigh performance liquid chromatography-mass spectrometry. Between-treatment differences in metabolites were examined using orthogonal partial least square-discriminant analysis and mixed-effect models. Secondary outcomes include blood pressure, corticotropin-releasing hormone, adrenocorticotropic hormone, insulin resistance, and biomarkers of oxidative stress and inflammation.

Results:

The average personal exposure to PMs with aerodynamic diameters ≤2.5 μm was 24.3 μg/m 3 during the real purification and 53.1 μg/m 3 during the sham purification. Metabolomics analysis showed that higher exposure to PMs with aerodynamic diameters ≤2.5 μm led to significant increases in cortisol, cortisone, epinephrine, and norepinephrine. Between-treatment differences were also observed for glucose, amino acids, fatty acids, and lipids. We found significantly higher blood pressure, hormones, insulin resistance, and biomarkers of oxidative stress and inflammation among individuals exposed to higher PMs with aerodynamic diameters ≤2.5 μm.

Conclusions:

This study suggests that higher PM may induce metabolic alterations that are consistent with activations of the hypothalamus-pituitary-adrenal and sympathetic-adrenal-medullary axes, adding potential mechanistic insights into the adverse health outcomes associated with PM. Furthermore, our study demonstrated short-term reductions in stress hormone following indoor air purification.

Clinical Trial Registration:

URL: http://www.clinicaltrials.gov . Unique identifier: NCT02712333.

Bioapplications of Electrochemical Sensors and Biosensors

Recent progress in the electrochemical field enabled development of miniaturized sensing devices that can be used in biological settings to obtain fundamental and practical biochemically relevant information on physiology, metabolism, and disease states in living systems. Electrochemical sensors and biosensors have demonstrated potential for rapid, real-time measurements of biologically relevant molecules. This chapter provides an overview of the most recent advances in the development of miniaturized sensors for biological investigations in living systems, with focus on the detection of neurotransmitters and oxidative stress markers. The design of electrochemical (bio)sensors, including their detection mechanism and functionality in biological systems, is described as well as their advantages and limitations. Application of these sensors to studies in live cells, embryonic development, and rodent models is discussed.

Life Is Simple-Biologic Complexity Is an Epiphenomenon

Life originated from unicellular organisms by circumventing the Second Law of Thermodynamics using the First Principles of Physiology, namely negentropy, chemiosmosis and homeostatic regulation of calcium and lipids. It is hypothesized that multicellular organisms are merely contrivances or tools, used by unicellular organisms as agents for the acquisition of epigenetic inheritance. The First Principles of Physiology, which initially evolved in unicellular organisms are the exapted constraints that maintain, sustain and perpetuate that process. To ensure fidelity to this mechanism, we must return to the first principles of the unicellular state as the determinants of the primary level of selection pressure during the life cycle. The power of this approach is reflected by examples of its predictive value. This perspective on life is a "game changer", mechanistically rendering transparent many dogmas, teleologies and tautologies that constrain the current descriptive view of Biology.

On the Evolution of the Mammalian Brain

Hobson and Friston have hypothesized that the brain must actively dissipate heat in order to process information (Hobson et al., 2014). This physiologic trait is functionally homologous with the first instantation of life formed by lipids suspended in water forming micelles- allowing the reduction in entropy (heat dissipation). This circumvents the Second Law of Thermodynamics permitting the transfer of information between living entities, enabling them to perpetually glean information from the environment, that is felt by many to correspond to evolution per se. The next evolutionary milestone was the advent of cholesterol, embedded in the cell membranes of primordial eukaryotes, facilitating metabolism, oxygenation and locomotion, the triadic basis for vertebrate evolution. Lipids were key to homeostatic regulation of calcium, forming calcium channels. Cell membrane cholesterol also fostered metazoan evolution by forming lipid rafts for receptor-mediated cell-cell signaling, the origin of the endocrine system. The eukaryotic cell membrane exapted to all complex physiologic traits, including the lung and brain, which are molecularly homologous through the function of neuregulin, mediating both lung development and myelinization of neurons. That cooption later exapted as endothermy during the water-land transition (Torday, 2015a), perhaps being the functional homolog for brain heat dissipation and conscious/mindful information processing. The skin and brain similarly share molecular homologies through the “skin-brain” hypothesis, giving insight to the cellular-molecular “arc” of consciousness from its unicellular origins to integrated physiology. This perspective on the evolution of the central nervous system clarifies self-organization, reconciling thermodynamic and informational definitions of the underlying biophysical mechanisms, thereby elucidating relations between the predictive capabilities of the brain and self-organizational processes.

GABA Signaling and Neuroactive Steroids in Adrenal Medullary Chromaffin Cells

Gamma-aminobutyric acid (GABA) is produced not only in the brain, but also in endocrine cells by the two isoforms of glutamic acid decarboxylase (GAD), GAD65 and GAD67. In rat adrenal medullary chromaffin cells only GAD67 is expressed, and GABA is stored in large dense core vesicles (LDCVs), but not synaptic-like microvesicles (SLMVs). The α3β2/3γ2 complex represents the majority of GABAA receptors expressed in rat and guinea pig chromaffin cells, whereas PC12 cells, an immortalized rat chromaffin cell line, express the α1 subunit as well as the α3. The expression of α3, but not α1, in PC12 cells is enhanced by glucocorticoid activity, which may be mediated by both the mineralocorticoid receptor (MR) and the glucocorticoid receptor (GR). GABA has two actions mediated by GABAA receptors in chromaffin cells: it induces catecholamine secretion by itself and produces an inhibition of synaptically evoked secretion by a shunt effect. Allopregnanolone, a neuroactive steroid which is secreted from the adrenal cortex, produces a marked facilitation of GABAA receptor channel activity. Since there are no GABAergic nerve fibers in the adrenal medulla, GABA may function as a para/autocrine factor in the chromaffin cells. This function of GABA may be facilitated by expression of the immature isoforms of GAD and GABAA receptors and the lack of expression of plasma membrane GABA transporters (GATs). In this review, we will consider how the para/autocrine function of GABA is achieved, focusing on the structural and molecular mechanisms for GABA signaling.

Feasibility of 24-Hr Urine Collection for Measurement of Biomarkers in Community-Dwelling Older Adults

Biologic markers are becoming a key part of gerontological research, including their measurement at multiple intervals to detect changes over time. This report examined the feasibility and quality of 24-hr urine collection to measure neuroendocrine biomarkers in a community-based sample of older caregivers and non-caregivers. At each interview, participants were instructed on the correct method to collect and store the sample. As incentives, participants selected a day for urine collection within 5 days of the interview, received a reimbursement, and study staff travelled to their home to retrieve the specimen. Between 2008 and 2013, 256 participants were enrolled; all but two participants (99%) provided a baseline urine specimen, of which 93% were considered adequate. Urine collection and quality remained high over three annual follow-up interviews and did not vary by caregiver status or perceived stress level. Our results indicate that 24-hr urine collection is feasible in active, community-dwelling older adults.

Adrenal Gland Microenvironment and Its Involvement in the Regulation of Stress-Induced Hormone Secretion during Sepsis

Survival of all living organisms depends on maintenance of a steady state of homeostasis, which process relies on its ability to react and adapt to various physical and emotional threats. The defense against stress is executed by the hypothalamic-pituitary-adrenal axis and the sympathetic-adrenal medullary system. Adrenal gland is a major effector organ of stress system. During stress, adrenal gland rapidly responds with increased secretion of glucocorticoids (GCs) and catecholamines into circulation, which hormones, in turn, affect metabolism, to provide acutely energy, vasculature to increase blood pressure, and the immune system to prevent it from extensive activation. Sepsis resulting from microbial infections is a sustained and extreme example of stress situation. In many critical ill patients, levels of both corticotropin-releasing hormone and adrenocorticotropin, the two major regulators of adrenal hormone production, are suppressed. Levels of GCs, however, remain normal or are elevated in these patients, suggesting a shift from central to local intra-adrenal regulation of adrenal stress response. Among many mechanisms potentially involved in this process, reduced GC metabolism and activation of intra-adrenal cellular systems composed of adrenocortical and adrenomedullary cells, endothelial cells, and resident and recruited immune cells play a key role. Hence, dysregulated function of any of these cells and cellular compartments can ultimately affect adrenal stress response. The purpose of this mini review is to highlight recent insights into our understanding of the adrenal gland microenvironment and its role in coordination of stress-induced hormone secretion.

Cortisol-dependent stress effects on cell distribution in healthy individuals and individuals suffering from chronic adrenal insufficiency

Chronic adrenal insufficiency (CAI) is characterized by a lack of glucocorticoid and mineralocorticoid production due to destroyed adrenal cortex cells. However, elevated cortisol secretion is thought to be a central part in a well-orchestrated immune response to stress. This raises the question to what extent lack of cortisol in CAI affects stress-related changes in immune processes. To address this question, 28 CAI patients (20 females) and 18 healthy individuals (11 females) (age: 44.3 ± 8.4 years) were exposed to a psychosocial stress test (Trier Social Stress Test: TSST). Half the patients received a 0.03 mg/kg body weight injection of hydrocortisone (HC) post-TSST to mimic a healthy cortisol stress response. Catecholamines and immune cell composition were assessed in peripheral blood and free cortisol measured in saliva collected before and repeatedly after TSST. CAI patients showed norepinephrine (NE) stress responses similar to healthy participants, however, epinephrine (E) as well as cortisol levels were significantly lower. HC treatment post-TSST resulted in cortisol increases comparable to those observed in healthy participants (interaction effects--NE: F=1.05, p=.41; E: F=2.56, p=.045; cortisol: F=13.28, p<.001). Healthy individuals showed the expected pattern of stress-related early lymphocyte increase with subsequent decrease below baseline. The opposite pattern was observed in granulocytes. While exhibiting a similar initial increase, lymphocytes kept increasing over the following 2h in untreated patients. HC treatment buffered this effect (interaction effects--lymphocyte%: F=7.31, p<.001; granulocyte%: F=7.71, p<.001). Using CAI in humans as a model confirms cortisol's central involvement in post-stress lymphocyte migration from blood into immune-relevant body compartments. As such, future studies should investigate whether psychosocial stress exposure may put CAI patients at an increased health risk due to attenuated immune responses to pathogens.

Glucocorticoids and Skeletal Muscle

Glucocorticoids are known to regulate protein metabolism in skeletal muscle, producing a catabolic effect that is opposite that of insulin. In many catabolic diseases, such as sepsis, starvation, and cancer cachexia, endogenous glucocorticoids are elevated contributing to the loss of muscle mass and function. Further, exogenous glucocorticoids are often given acutely and chronically to treat inflammatory conditions such as asthma, chronic obstructive pulmonary disease, and rheumatoid arthritis, resulting in muscle atrophy. This chapter will detail the nature of glucocorticoid-induced muscle atrophy and discuss the mechanisms thought to be responsible for the catabolic effects of glucocorticoids on muscle.

The Effect of Cooled Perches on Immunological Parameters of Caged White Leghorn Hens during the Hot Summer Months

The objective of this study was to determine if thermally cooled perches improve hen immunity during hot summer. White Leghorn pullets at 16 week of age were randomly assigned to 18 cages of 3 banks at 9 hens per cage. Each bank was assigned to 1 of the 3 treatments up to 32 week of age: 1) thermally cooled perches, 2) perches with ambient air, and 3) cages without perches. Hens were exposed to natural ambient temperatures from June through September 2013 in Indiana with a 4 h acute heat episode at 27.6 week of age. The packed cell volume, heterophil to lymphocyte (H/L) ratio, plasma concentrations of total IgG, and cytokines of interleukin-1β and interleukin-6, plus lipopolysaccharide-induced tumor necrosis factor-α factor were measured at both 27.6 and 32 week of age. The mRNA expressions of these cytokines, toll-like receptor-4, and inducible nitric oxide synthase were also examined in the spleen of 32 week-old hens. Except for H/L ratio, thermally cooled perches did not significantly improve currently measured immunological indicators. These results indicated that the ambient temperature of 2013 summer in Indiana (24°C, 17.1 to 33.1°C) was not high enough and the 4 h heat episode at 33.3°C (32 to 34.6°C) was insufficient in length to evoke severe heat stress in hens. However, cooled perch hens had a lower H/L ratio than both air perch hens and control hens at 27.6 week of age and it was still lower compared to control hens (P < 0.05, respectively) at 32 week of age. The lowered H/L ratio of cooled perch hens may suggest that they were able to cope with acute heat stress more effectively than control hens. Further studies are needed to evaluate the effectiveness of thermally cooled perches on hen health under higher ambient temperatures.

Homeostasis as the Mechanism of Evolution

Homeostasis is conventionally thought of merely as a synchronic (same time) servo-mechanism that maintains the status quo for organismal physiology. However, when seen from the perspective of developmental physiology, homeostasis is a robust, dynamic, intergenerational, diachronic (across-time) mechanism for the maintenance, perpetuation and modification of physiologic structure and function. The integral relationships generated by cell-cell signaling for the mechanisms of embryogenesis, physiology and repair provide the needed insight to the scale-free universality of the homeostatic principle, offering a novel opportunity for a Systems approach to Biology. Starting with the inception of life itself, with the advent of reproduction during meiosis and mitosis, moving forward both ontogenetically and phylogenetically through the evolutionary steps involved in adaptation to an ever-changing environment, Biology and Evolution Theory need no longer default to teleology.

Circadian hormone profiles and insulin sensitivity in patients with Addison's disease: a comparison of continuous subcutaneous hydrocortisone infusion with conventional glucocorticoid replacement therapy

CONTEXT

Conventional glucocorticoid replacement therapy in patients with Addison's disease (AD) is unphysiological with possible adverse effects on mortality, morbidity and quality of life. The diurnal cortisol profile can likely be restored by continuous subcutaneous hydrocortisone infusion (CSHI).

OBJECTIVE

The aim of this study was to compare circadian hormone rhythms and insulin sensitivity in conventional thrice-daily regimen of glucocorticoid replacement therapy with CSHI treatment in patients with AD.

DESIGN AND SETTING

An open, randomized, two-period, 12-week crossover multicentre trial in Norway and Sweden.

PATIENTS

Ten Norwegian patients were admitted for 24-h sampling of hormone profiles. Fifteen Swedish patients underwent euglycaemic-hyperinsulinaemic clamp.

INTERVENTION

Thrice-daily regimen of oral hydrocortisone (OHC) and CSHI treatment.

MAIN OUTCOME MEASURE

We measured the circadian rhythm of cortisol, adrenocorticotropic hormone (ACTH), growth hormone (GH), insulin-like growth factor-1, (IGF-1), IGF-binding protein-3 (IGFBP-3), glucose, insulin and triglycerides during OHC and CSHI treatment. Euglycaemic-hyperinsulinaemic clamp was used to assess insulin sensitivity.

RESULTS

Continuous subcutaneous hydrocortisone infusion provided a more physiological circadian cortisol curve including a late-night cortisol surge. ACTH levels showed a near normal circadian variation for CSHI. CSHI prevented a continuous decrease in glucose during the night. No difference in insulin sensitivity was observed between the two treatment arms.

CONCLUSION

Continuous subcutaneous hydrocortisone infusion replacement re-established a circadian cortisol rhythm and normalized the ACTH levels. Patients with CSHI replacement had a more stable night-time glucose level compared with OHC without compromising insulin sensitivity. Thus, restoring night-time cortisol levels might be advantageous for patients with AD.

A central theory of biology

The history of physiologic cellular-molecular interrelationships can be traced all the way back to the unicellular state by following the pathway formed by lipids ubiquitously accommodating calcium homeostasis, and its consequent adaptive effects on oxygen uptake by cells, tissues and organs. As a result, a cohesive, mechanistically integrated view of physiology can be formulated by recognizing the continuum comprising conception, development, physiologic homeostasis and death mediated by soluble growth factor signaling. Seeing such seemingly disparate processes as embryogenesis, chronic disease and dying as the gain and subsequent loss of cell-cell signaling provides a novel perspective for physiology and medicine. It is emblematic of the self-organizing, self-referential nature of life, starting from its origins. Such organizing principles obviate the pitfalls of teleologic evolution, conversely providing a way of resolving such seeming dichotomies as holism and reductionism, genotype and phenotype, emergence and contingence, proximate and ultimate causation in evolution, cells and organisms. The proposed approach is scale-free and predictive, offering a Central Theory of Biology.

Evolution and Cell Physiology. 1. Cell signaling is all of biology

I hypothesize that the First Principles of Physiology (FPPs) were co-opted during the vertebrate transition from water to land, beginning with the acquisition of cholesterol by eukaryotes, facilitating unicellular evolution over the course of the first 4.5 billion years of the Earth's history, in service to the reduction in intracellular entropy, far from equilibrium. That mechanism was perpetuated by the advent of cholesterol in the cell membrane of unicellular eukaryotes, ultimately giving rise to the metazoan homologs of the gut, lung, kidney, skin, bone, and brain. Parathyroid hormone-related protein (PTHrP), whose cognate receptor underwent a gene duplication during the transition from fish to amphibians, facilitated gas exchange for the water-to-land transition, since PTHrP is necessary for the formation of lung alveoli: deletion of the PTHrP gene in mice causes the offspring to die within a few minutes of birth due to the absence of alveoli. Moreover, PTHrP is central to the development and homeostasis of the kidney, skin, gut, bone, and brain. Therefore, duplication of the PTHrP receptor gene is predicted to have facilitated the molecular evolution of all the necessary traits for land habitation through a common cellular and molecular motif. Subsequent duplication of the β-adrenergic receptor gene permitted blood pressure control within the lung microvasculature, allowing further evolution of the lung by increasing its surface area. I propose that such gene duplications were the result of shear stress on the microvasculature, locally generating radical oxygen species that caused DNA mutations, giving rise to duplication of the PTHrP and β-adrenergic receptor genes. I propose that one can determine the FPPs by systematically tracing the molecular homologies between the lung, skin, kidney, gut, bone, and brain across development, phylogeny, and pathophysiology as a type of "reverse evolution." By tracing such relationships back to unicellular organisms, one can use the underlying principles to predict homeostatic failure as disease, thereby also potentially forming the basis for maneuvers that can treat or even prevent such failure.

Interpreting Stress Responses during Routine Toxicity Studies

Stress often occurs during toxicity studies. The perception of sensory stimuli as stressful primarily results in catecholamine release and activation of the hypothalamic–pituitary–adrenal (HPA) axis to increase serum glucocorticoid concentrations. Downstream effects of these neuroendocrine signals may include decreased total body weights or body weight gain; food consumption and activity; altered organ weights (e.g., thymus, spleen, adrenal); lymphocyte depletion in thymus and spleen; altered circulating leukocyte counts (e.g., increased neutrophils with decreased lymphocytes and eosinophils); and altered reproductive functions. Typically, only some of these findings occur in a given study. Stress responses should be interpreted as secondary (indirect) rather than primary (direct) test article–related findings. Determining whether effects are the result of stress requires a weight-of-evidence approach. The evaluation and interpretation of routinely collected data (standard in-life, clinical pathology, and anatomic pathology endpoints) are appropriate and generally sufficient to assess whether or not changes are secondary to stress. The impact of possible stress-induced effects on data interpretation can partially be mitigated by toxicity study designs that use appropriate control groups (e.g., cohorts treated with vehicle and subjected to the same procedures as those dosed with test article), housing that minimizes isolation and offers environmental enrichment, and experimental procedures that minimize stress and sampling and analytical bias.

This article is a comprehensive overview of the biological aspects of the stress response, beginning with a Summary (Section 1) and an Introduction (Section 2) that describes the historical and conventional methods used to characterize acute and chronic stress responses. These sections are followed by reviews of the primary systems and parameters that regulate and/or are influenced by stress, with an emphasis on parameters evaluated in toxicity studies: In-life Procedures (Section 3), Nervous System (Section 4), Endocrine System (Section 5), Reproductive System (Section 6), Clinical Pathology (Section 7), and Immune System (Section 8). The paper concludes (Section 9) with a brief discussion on Minimizing Stress-Related Effects (9.1.), and a final section explaining why Parameters routinely measured are appropriate for assessing the role of stress in toxicology studies (9.2.).

Effect of acute heat stress on rat adrenal medulla — a morphological and ultrastructural study

Isolated rat adrenal medulla was analyzed by light and electron microscope after an acute (60 min) exposure to high ambient temperature (38°C). Under these conditions there was a significant rise in plasma adrenaline and noradrenaline. Stereological investigation by light microscopy showed a significant decrease in volume density of cells and an increase in the interstitium. At the ultrastructural level, the profile area of cells, nuclei and cytoplasm of adrenaline cells were significantly decreased. After the heat stress numbers of resting granules in adre naline and noradrenaline cells were significantly reduced, while the numbers of altered granules and empty containers in both types of adrenomedullar cells were significantly increased.

Stress and skin leukocyte trafficking as a dual-stage process

Stress responses are known to modulate leukocyte trafficking. In the skin, stress was reported both to enhance and reduce skin immunity, and the chronicity of stress exposure was suggested as a key determining factor. We here propose a dual-stage hypothesis, suggesting that stress, of any duration, reduces skin immunity during its course, while its cessation is potentially followed by a period of enhanced skin immunity. To start testing this hypothesis, rats were subcutaneously implanted with sterile surgical sponges for four-hours, during or after exposure to one of several acute stress paradigms, or to a chronic stress paradigm. Our findings, in both males and females, indicate that numbers of sponge-infiltrating leukocytes, and their specific subsets, were reduced during acute or chronic stress, and increased after stress cessation. Studying potential mediating mechanisms of the reduction in leukocyte numbers during acute stress, we found that neither adrenalectomy nor the administration of beta-adrenergic or glucocorticoid antagonists prevented this reduction. Additionally, administration of corticosterone or epinephrine to adrenalectomized rats did not impact skin leukocyte numbers, whereas, in the blood, these treatments did affect numbers of leukocytes and their specific subsets, as was also reported previously. Overall, our findings support the proposed dual-stage hypothesis, which can be evolutionally rationalized and accounts for most of the apparent inconsistencies in the literature regarding stress and skin immunity. Other aspects of the hypothesis should be tested, also using additional methodologies, and its predictions may bear clinical significance in treatment of skin disorders related to hyper- or hypo-immune function.

Acetylation-mediated epigenetic regulation of glucocorticoid receptor activity: circadian rhythm-associated alterations of glucocorticoid actions in target tissues

Glucocorticoids influence organ functions through the glucocorticoid receptor, a protein acetylated and deacetylated by several histone acetyltransferases and deacetylases. We reported that the circadian rhythm-related transcription factor "Clock", a key component of the biological CLOCK with inherent histone acetyltransferase activity, acetylates glucocorticoid receptor lysines within its hinge region--a "lysine cluster" containing a KXKK motif--and represses its transcriptional activity. This Clock-induced repression of the glucocorticoid receptor activity is inversely phased to the diurnally circulating glucocorticoids and may act as a local counter regulatory mechanism to the actions of these hormones. Importantly, uncoupling of the central CLOCK-regulated hypothalamic-pituitary-adrenal axis and peripheral CLOCK-mediated alterations of glucocorticoid action, such as chronic stress and frequent trans-time zone travel or night-shift work, may cause functional hypercortisolism and contribute to various pathologies. Thus, acetylation-mediated epigenetic regulation of the glucocorticoid receptor may be essential for the maintenance of proper time-integrated glucocorticoid action, significantly influencing human well-being and longevity.

Painful hypoadrenalism

A 61-year-old man presented with diffuse myalgia and arthralgia. The physical examination showed diffuse musculoskeletal tenderness and joint stiffness without the presence of synovitis or arthritis. Nerve conduction study showed combined mild axonal degenerative and demyelinating change. Muscle biopsy analysis showed unspecific mild muscle atrophy with myopathic changes found on electromyography. A diagnosis of isolated adrenocorticotropic hormone deficiency was made on the basis of endocrinological evaluation. The widespread musculoskeletal pain resolved as a result of administration of physiological dose of hydrocortisone replacement. In a patient with unexplained rheumatic symptoms, adrenocortical insufficiency should be considered in the possible aetiology.

Chronic cardiac pressure overload induces adrenal medulla hypertrophy and increased catecholamine synthesis

Increased activity of the sympathetic system is an important feature contributing to the pathogenesis and progression of chronic heart failure. While the mechanisms and consequences of enhanced norepinephrine release from sympathetic nerves have been intensely studied, the role of the adrenal gland in the development of cardiac hypertrophy and progression of heart failure is less well known. Thus, the aim of the present study was to determine the effect of chronic cardiac pressure overload in mice on adrenal medulla structure and function. Cardiac hypertrophy was induced in wild-type mice by transverse aortic constriction (TAC) for 8 weeks. After TAC, the degree of cardiac hypertrophy correlated significantly with adrenal weight and adrenal catecholamine storage. In the medulla, TAC caused an increase in chromaffin cell size but did not result in chromaffin cell proliferation. Ablation of chromaffin α(2C)-adrenoceptors did not affect adrenal weight or epinephrine synthesis. However, unilateral denervation of the adrenal gland completely prevented adrenal hypertrophy and increased catecholamine synthesis. Transcriptome analysis of microdissected adrenal medulla identified 483 up- and 231 downregulated, well-annotated genes after TAC. Among these genes, G protein-coupled receptor kinases 2 (Grk2) and 6 and phenylethanolamine N-methyltransferase (Pnmt) were significantly upregulated by TAC. In vitro, acetylcholine-induced Pnmt and Grk2 expression as well as enhanced epinephrine content was prevented by inhibition of nicotinic acetylcholine receptors and Ca(2+)/calmodulin-dependent signaling. Thus, activation of preganglionic sympathetic nerves innervating the adrenal medulla plays an essential role in inducing adrenal hypertrophy, enhanced catecholamine synthesis and induction of Grk2 expression after cardiac pressure overload.