Constantine Tsigos

Chronic insomnia and activity of the stress system ☆: A preliminary study

The aim of this study was to assess whether there is an association between chronic insomnia and the activity of the stress system. Fifteen young adult insomniacs (<40 years) were studied. After an adaptation night, each subject was recorded in the sleep laboratory for three consecutive nights. During this period, 24-hour urine specimens were collected for measurements of urinary free cortisol (UFC), catecholamines, and growth hormone (GH). The 24-hour UFC levels were positively correlated with total wake time (p=0.05). In addition, 24-hour urinary levels of catecholamine metabolites, DHPG, and DOPAC were positively correlated with percent stage 1 sleep (p<0.05) and wake time after sleep onset (WTASO) (p<0.05). Norepinephrine tended to correlate positively with percent stage 1 sleep (p=0.063) and WTASO (p=0.074), and negatively with percent slow-wave sleep (p=0.059). Twenty-four-hour urinary GH excretion was detectable in only three insomniacs, two of whom had low indices of sleep disturbance. We conclude that, in chronic insomnia, the activity of both limbs of the stress system (i.e., the HPA axis and the sympathetic system) relates positively to the degree of objective sleep disturbance.

Management of Obesity in Adults: European Clinical Practice Guidelines

The development of consensus guidelines for obesity is complex. It involves recommending both treatment interventions and interventions related to screening and prevention. With so many publications and claims, and with the awareness that success for the individual is short-lived, many find it difficult to know what action is appropriate in the management of obesity. Furthermore, the significant variation in existing service provision both within countries as well as across the regions of Europe makes a standardised approach, even if evidence-based, difficult to implement. In formulating these guidelines, we have attempted to use an evidence-based approach while allowing flexibility for the practicing clinician in domains where evidence is currently lacking and ensuring that in treatment there is recognition of clinical judgment and of regional diversity as well as the necessity of an agreed approach by the individual and family. We conclude that i) physicians have a responsibility to recognise obesity as a disease and help obese patients with appropriate prevention and treatment, ii) treatment should be based on good clinical care and evidence-based interventions and iii) obesity treatment should focus on realistic goals and lifelong management.

Stress, Visceral Obesity, and Metabolic Complications

Abstract:  Stress is a state of threatened homeostasis or disharmony caused by intrinsic or extrinsic adverse forces and is counteracted by an intricate repertoire of physiologic and behavioral responses that aim to reestablish the challenged body equilibrium. The adaptive stress response depends upon an elaborate neuroendocrine, cellular, and molecular infrastructure, the stress system. Crucial functions of the stress system response are mediated by the hypothalamic‐pituitary‐adrenal (HPA) axis and the central and peripheral components of the autonomic nervous system (ANS). The integrity of the HPA axis and the ANS and their precise interactions with other CNS components are essential for a successful response to the various stressors. Chronic stress represents a prolonged threat to homeostasis by persistent or frequently repeated stressors and may lead to manifestations that characterize a wide range of diseases and syndromes. Such states progressively lead to a deleterious overload with complications caused by both the persistent stressor and the detrimental prolongation of the adaptive response. The metabolic syndrome can be described as a state of deranged metabolic homeostasis characterized by the combination of central obesity, insulin resistance, dyslipidemia, and hypertension. The incidence of both obesity and the metabolic syndrome in modern Western societies has taken epidemic proportions over the past decades and often correlates with indices of stress in the affected populations. Stress, primarily through hyperactivation of the HPA axis, appears to contribute to the accumulation of fat tissue, and vice versa, obesity itself seems to constitute a chronic stressful state and may cause HPA axis dysfunction. In addition, the description of obesity as a systemic low grade inflammatory condition that contributes to the derangement of the metabolic equilibrium implies that the proinflammatory cytokines which are secreted by the adipocytes hold a potentially important pathogenetic role. In this article we describe the physiology of the stress system response, with emphasis on metabolism, and review the recent data that implicate several neuroendocrine and inflammatory mechanisms mobilized during chronic stress in the development of the metabolic complications that characterize central obesity and the metabolic syndrome.

Circulating tumor necrosis factor alpha concentrations are higher in abdominal versus peripheral obesity

Fat tissue is a significant source of endogenous tumor necrosis factor alpha (TNFalpha), the pluripotent cytokine that plays an important role as a mediator of the peripheral insulin resistance found in obesity. The majority of evidence for this role of TNFalpha is from studies in animal models of obesity. To explore further the role of TNFalpha in the pathogenesis of obesity-related insulin resistance in humans, we compared plasma levels of TNFalpha and the other main endocrine cytokine, interleukin-6 ([IL-6] both measured by enzyme-linked immunosorbent assay), in 26 obese women (body mass index [BMI] > 30 kg/m2) and 13 female controls (BMI < 26 kg/m2) without a history of recent or active infection. Glucose and insulin levels were measured at 0, 1, and 2 hours after a 75-g oral glucose load. There was no significant difference in plasma TNFalpha or IL-6 levels between obese and non-obese subjects overall (2.10 +/- 0.19 v 1.65 +/- 0.18 pg/mL and 2.06 +/- 0.29 v 1.50 +/- 0.17 pg/mL, respectively). However, TNFalpha levels were significantly elevated in obese subjects with a 2-hour glucose level more than 140 mg/dL (n = 8) compared with the other obese subjects (n = 18) and the non-obese controls (2.88 +/- 0.46 v 1.75 +/- 0.10 and 1.65 +/- 0.18 pg/mL, respectively, P < .01). Furthermore, the TNFalpha level correlated significantly with the waist to hip ratio ([WHR] r = .53, P < .01) and fasting and post-oral glucose tolerance test (OGTT) insulin levels (r = .47, P < .02), but not with the BMI, and was higher in obese women with a WHR more than 0.90 (n = 14) in comparison to those with a WHR less than 0.90 (n = 12, 2.47 +/- 0.29 v 1.66 +/- 0.18 pg/mL, respectively, P < .03). The corresponding plasma leptin level was significantly higher in obese women versus the control group (41.6 +/- 2.5 v22.3 +/- 2.9 ng/mL, P < .001) and was related to the BMI (r = .60, P < .01) but not to TNFalpha or the WHR. There were no significant differences in the corresponding IL-6 concentration between groups, and IL-6 did not correlate with TNFalpha, leptin, BMI, WHR, or insulin levels. In conclusion, circulating TNFalpha levels are higher in abdominal obesity compared with peripheral obesity, and may contribute to the insulin resistance that more commonly complicates the former pattern of fat distribution.

Stress hormones: physiological stress and regulation of metabolism.

Stress, defined as a state of threatened homeostasis, mobilizes a complex spectrum of adaptive physiologic and behavioral responses that aim to re-establish the challenged body homeostasis. The hypothalamic-pituitary-adrenal (HPA) axis and the sympathetic nervous system (SNS) constitute the main effector pathways of the stress system, mediating its adaptive functions. In western societies, indices of stress correlate with increasing rates of both obesity and metabolic syndrome which have reached epidemic proportions. Recent data indicate that chronic stress, associated with mild hypercortisolemia and prolonged SNS activation, favors accumulation of visceral fat and contributes to the clinical presentation of visceral obesity, type 2 diabetes, and related cardiometabolic complications. Reciprocally, obesity promotes a systemic low-grade inflammation state, mediated by increased adipokine secretion, which can chronically stimulate the stress system.

The maternal hypothalamic–pituitary–adrenal axis in the third trimester of human pregnancy

OBJECTIVE The third trimester of pregnancy is characterized by a mildly hyperactive hypothalamic–pituitary–adrenal (HPA) axis, possibly driven by elevated circulating levels of corticotrophin releasing hormone (CRH) of placental origin. In‐vitro studies have demonstrated that glucocorticoids and oestrogen stimulate while progesterone inhibits the expression of CRH mRNA and/or protein, suggesting that several potential interactions between the placenta and the HPA axis may exist.

Prevalence, Pathophysiology, Health Consequences and Treatment Options of Obesity in the Elderly: A Guideline

The prevalence of obesity is rising progressively, even among older age groups. By the year 2030–2035 over 20% of the adult US population and over 25% of the Europeans will be aged 65 years and older. The predicted prevalence of obesity in Americans, 60 years and older was 37% in 2010. The predicted prevalence of obesity in Europe in 2015 varies between 20 and 30% dependent on the model used. This means 20.9 million obese 60+ people in the USA in 2010 and 32 million obese elders in 2015 in the EU. Although cut-off values of BMI, waist circumference and percentages of fat mass have not been defined for the elderly (nor for the elderly of different ethnicity), it is clear from several meta-analyses that mortality and morbidity associated with overweight and obesity only increases at a BMI above 30 kg/m2. Thus, treatment should only be offered to patients who are obese rather than overweight and who also have functional impairments, metabolic complications or obesity-related diseases, that can benefit from weight loss. The weight loss therapy should aim to minimize muscle and bone loss but also vigilance as regards the development of sarcopenic obesity – a combination of an unhealthy excess of body fat with a detrimental loss of muscle and fat-free mass including bone – is important in the elderly, who are vulnerable to this outcome. Life-style intervention should be the first step and consists of a diet with a 500 kcal (2.1 MJ) energy deficit and an adequate intake of protein of high biological quality together with calcium and vitamin D, behavioural therapy and multi-component exercise. Multi-component exercise includes flexibility training, balance training, aerobic exercise and resistance training. The adherence rate in most studies is around 75%. Knowledge of constraints and modulators of physical inactivity should be of help to engage the elderly in physical activity. The role of pharmacotherapy and bariatric surgery in the elderly is largely unknown as in most studies people aged 65 years and older have been excluded.

European Guidelines for Obesity Management in Adults

Obesity is a chronic metabolic disease characterised by an increase of body fat stores. It is a gateway to ill health, and it has become one of the leading causes of disability and death, affecting not only adults but also children and adolescents worldwide. In clinical practice, the body fatness is estimated by BMI, and the accumulation of intra-abdominal fat (marker for higher metabolic and cardiovascular disease risk) can be assessed by waist circumference. Complex interactions between biological, behavioural, social and environmental factors are involved in regulation of energy balance and fat stores. A comprehensive history, physical examination and laboratory assessment relevant to the patients obesity should be obtained. Appropriate goals of weight management emphasise realistic weight loss to achieve a reduction in health risks and should include promotion of weight loss, maintenance and prevention of weight regain. Management of co-morbidities and improving quality of life of obese patients are also included in treatment aims. Balanced hypocaloric diets result in clinically meaningful weight loss regardless of which macronutrients they emphasise. Aerobic training is the optimal mode of exercise for reducing fat mass while a programme including resistance training is needed for increasing lean mass in middle-aged and overweight/obese individuals. Cognitive behavioural therapy directly addresses behaviours that require change for successful weight loss and weight loss maintenance. Pharmacotherapy can help patients to maintain compliance and ameliorate obesity-related health risks. Surgery is the most effective treatment for morbid obesity in terms of long-term weight loss. A comprehensive obesity management can only be accomplished by a multidisciplinary obesity management team. We conclude that physicians have a responsibility to recognise obesity as a disease and help obese patients with appropriate prevention and treatment. Treatment should be based on good clinical care, and evidence-based interventions; should focus on realistic goals and lifelong multidisciplinary management.

Dose-Dependent Effects of Recombinant Human Interleukin-6 on the Pituitary-Testicular Axis

Inflammatory cytokines are soluble mediators of immune function that also regulate intermediate metabolism and several endocrine axes. To examine the effects of interleukin-6 (IL-6), the main circulating cytokine, on the hypothalamic-pituitary-testicular axis in men, we performed dose-response studies of recombinant human IL-6 (rHuIL-6) in normal volunteers. Increasing single doses of IL-6 (0.1, 0.3, 1.0, 3.0, and 10.0 microg/kg body weight) were injected subcutaneously into 15 healthy male volunteers (3 at each dose) in the morning. We measured the circulating levels of testosterone, luteinizing hormone (LH), follicle-stimulating hormone (FSH), and sex hormone binding globulin (SHBG) at baseline and then at 24 h, 48 h, and 7 days after the IL-6 injection. LH and FSH levels were also measured half-hourly for the first 4 h after the IL-6 injection. All IL-6 doses were tolerated well and produced no significant adverse effects. Mean peak plasma IL-6 levels achieved after IL-6 administration were 8 +/- 1, 22 +/- 5, 65 +/- 22, 290 +/- 38, and 4050 +/- 149 pg/ml, respectively for the five doses. We observed no significant changes in plasma testosterone levels after the two smaller IL-6 doses. The three higher IL-6 doses, however, caused significant decreases in testosterone levels by 24 h, which persisted at 48 h and returned to baseline by 7 days. The higher testosterone suppression was after the 3.0 microg/kg dose, making the dose-response curve bell-shaped. There also appeared to be small but not significant increases in LH levels after the three higher IL-6 doses, which were not acute and seemed to follow temporally the testosterone decreases. The concurrent plasma levels of FSH and SHBG were not appreciably affected by any IL-6 dose. In conclusion, subcutaneous IL-6 administration, which caused acute elevations in circulating IL-6 levels of a similar magnitude to those observed in severe inflammatory and noninflammatory stress, induced prolonged suppression in testosterone levels in healthy men without apparent changes in gonadotropin levels. This suggests that IL-6 might induce persistent testicular resistance to LH action or suppression of Leydig cell steroidogenesis or both, with potential adverse effects on male reproductive function.

Stress, the Endoplasmic Reticulum, and Insulin Resistance

Abstract:  Stress, such as nutrient deprivation, viral infections, inflammation, heat shock, or lipid accumulation, imposes a serious threat to the body. These stimuli, acting both on the central control stations of the stress system and its final effectors, catecholamines and glucocorticoids, and on the peripheral target tissues, can modulate insulin action in the body. Metabolic complications, such as diabetes, visceral obesity, and atherosclerosis have emerged as major health threats in the modern societies. Indeed, obesity and atherosclerosis are regarded as states of chronic low‐grade inflammation, while inflammatory mediators and lipid accumulation can evoke a chronic stress at the cellular level, principally affecting the endoplasmic reticulum (ER). It has recently been shown that ER responds to metabolic stressors through a well coordinated molecular response that involves the transcriptional activation of multiple genes, the attenuation of protein synthesis and degradation of the ER‐localized misfolded proteins, and the onset of apoptosis. This article examines the emerging role of stress on ER and its possible link with obesity, insulin resistance, and type 2 diabetes.