Stress-related cortisol secretion in men: relationships with abdominal obesity and endocrine, metabolic and hemodynamic abnormalities

Treadmill exercise training fails to reverse defects in glucose, insulin and muscle GLUT4 content in the db/db mouse model of diabetes

OBJECTIVE

Regular exercise is recommended for the treatment of type 2 diabetes because of the benefits on body weight and glycemic control. The present study was designed to compare the impact of voluntary wheel and forced treadmill running on the metabolic state in the db/db mouse model of type 2 diabetes. Our hypothesis is that voluntary exercise training reduces body weight, blood glucose and insulin levels and restores GLUT4 levels in skeletal muscle, whereas forced exercise training produces a greater effect.

STUDY DESIGN

Male diabetic db/db mice were assigned to sedentary (DS), voluntary wheel running (DV), and forced treadmill running (DT) groups for 12 weeks. Nondiabetic heterozygote littermates served as control (CN).

RESULTS

Over the 12-week period, DV and DT mice ran a total of 4.24+/-0.18km and 11.8km, respectively. At week 12, fasting plasma glucose was decreased in DV mice compared to DS mice and occurred in the absence weight loss. In DT mice, body weight and fasting plasma glucose were not improved with exercise when compared to DS mice and were actually higher compared to DV mice. After training, fasting plasma insulin was increased in DS mice compared to CN mice and training failed to normalize plasma insulin levels. Gastrocnemius GLUT4 content was reduced in DS mice compared to CN mice and training had no effect in preventing this depression from occurring.

CONCLUSION

The results of this study indicate that while voluntary exercise improved only blood glucose, forced treadmill exercise training failed to restore body weight, blood glucose and insulin, and muscle GLUT4 content.

Environmental stress, erythrocyte dysfunctions, inflammation, and the metabolic syndrome: adaptations to CO2 increases?

In the Western world, the prevalence of the metabolic syndrome is increasing exponentially. Chronic subacute inflammation characterizes the syndrome, suggesting that inflammation might be a common denominator that links obesity to its pathologic sequelae. Potential mechanisms for the activation of inflammation include current air pollution inhalation and/or excess food intake. Both of these environmental factors have, in fact, been shown to promote oxidation followed by the release of proinflammatory cytokines. Potential sources of systemic inflammation include oxidized erythrocytes. Increased exogenous or endogenous CO2 deoxygenates hemoglobin, thereby increasing the fraction of hemoglobin reacting with nitrite to form methemoglobin together with release of superoxide and nitric oxide. These may form peroxynitrite, which may oxidize erythrocytes. Macrophages may then recognize and engulf these cells, thereby releasing proinflammatory cytokines. Therefore, studies should focus on the red blood cell and its proteins to finely target and appropriately treat a world pandemic ominously related to CO2 increases.

Are hormonal responses to exercise in young men with Down's syndrome related to reduced endurance performance?

The aim of the present study was to analyse whether hormonal responses could explain an exercise limitation in Down's syndrome (DS). Fourteen young men with DS (mean age 22.5 +/- 0.7 years) and 15 controls (CONT, mean age 22.5 +/- 0.3 years) participated in the study. During a treadmill submaximal incremental test, blood samples were collected for determination of hormonal and metabolic variables. Compared to CONT, DS individuals showed lower VO(2max) (P < 0.05), and lower duration of submaximal incremental exercise (P < 0.001). At rest, DS individuals showed greater catecholamines, insulin and leptin values (P < 0.05), but lower testosteronemia and cortisolemia (P < 0.05), compared to CONT. During submaximal incremental tests, catecholamines and cortisol were not increased, whereas the insulin concentration of DS individuals was significantly higher (P < 0.01) compared to CONT. Glycaemia increased significantly at the end of submaximal incremental test for CONT but not for DS individuals (P < 0.01). Maximal fat oxidation was lower (P < 0.01), whereas non-esterified fatty acids concentrations rose significantly during submaximal exercise in DS individuals. These results indicate an altered hormonal response to exercise in DS individuals. This endocrine profile at rest and during exercise may limit endurance performance in DS individuals.

The body politic: the relationship between stigma and obesity-associated disease

Background

It is commonly believed that the pathophysiology of obesity arises from adiposity. In this paper, I forward a complementary explanation; this pathophysiology arises not from adiposity alone, but also from the psychological stress induced by the social stigma associated with being obese.

Methods

In this study, I pursue novel lines of evidence to explore the possibility that obesity-associated stigma produces obesity-associated medical conditions. I also entertain alternative hypotheses that might explain the observed relationships.

Results

I forward four lines of evidence supporting the hypothesis that psychological stress plays a role in the adiposity-health association. First, body mass index (BMI) is a strong predictor of serological biomarkers of stress. Second, obesity and stress are linked to the same diseases. Third, body norms appear to be strong determinants of morbidity and mortality among obese persons; obese whites and women – the two groups most affected by weight-related stigma in surveys – disproportionately suffer from excess mortality. Finally, statistical models suggest that the desire to lose weight is an important driver of weight-related morbidity when BMI is held constant.

Conclusion

Obese persons experience a high degree of stress, and this stress plausibly explains a portion of the BMI-health association. Thus, the obesity epidemic may, in part, be driven by social constructs surrounding body image norms.

From integrative signalling to metabolic disorders

The adrenal cortex undergoes constant dynamic structural changes, a key element in ensuring integrative functionality of the gland. Studies have shown that the cellular environment can modulate cell functions such as proliferation and steroid secretion. For example, 3-day treatment with angiotensin II promotes protein synthesis with a concomitant decrease in proliferation of glomerulosa cells, when cultured on fibronectin, but not on collagen IV or laminin. These effects involve close interaction between cytoskeleton-associated proteins and activation of p42/p44mapk and p38 MAPK pathways. On the other hand, adrenocorticotropin hormone (ACTH), which is clearly the most potent stimulus of fasciculata cells, induces specific modulation of targeted proteins, when cells are cultured on collagen IV, but not on fibronectin or laminin. In particular, ACTH treatment leads to increased expression of Seladin-1 and induces the relocalization of Seladin-1 from the cytoplasm to the nucleus, both in vivo and in culture conditions, in adult rats and in human fetal adrenal glands. As a whole, these results indicate that Seladin-1, together with collagen IV, is able to modulate ACTH responsiveness. Hence, Seladin-1 may participate in the regulation of steroidogenesis when localized in the cytoplasm, while conversely protecting cells against oxidative stress generated by intense ACTH stimulation when massively localized in the nucleus.

Inflammation as an intermediate pathway in the association between psychosocial stress and obesity

Psychosocial stress is associated with risk of obesity although little is known about stress-induced biological mechanisms of obesity. We examined the potential mediating role of inflammatory processes. Data were collected from a nationally representative sample of 7540 individuals (54% women, mean age 46.8+/-15.4 years), from the Scottish Health Surveys. We calculated risk estimates of obesity for increasing numbers of psychosocial stressors (based on social position, education, psychological distress and marital/partner discord) using logistic regression analyses. Obesity was assessed using body mass index and central obesity using waist circumference. Potential mediators included inflammatory markers (C-reactive protein and fibrinogen) and health behaviours (physical activity, smoking, alcohol, and dietary intake). The unadjusted odds ratio of obesity for three or more psychosocial stressors was 1.81 (95% CI, 1.39-2.36, p<0.001). In multivariate analyses that adjusted for age, gender, health behaviours and inflammatory markers the association between psychosocial stress and obesity was attenuated but remained significant (1.49, 1.11-2.00, p<0.001). Inflammatory markers independently accounted for approximately 25% of the association between stress and obesity. We found similar associations in separate analyses of psychosocial stress and central obesity, although results were confounded by overall obesity. In summary, inflammatory processes appear to be an important intermediate pathway in the association between psychosocial stress and obesity.

Exploration of basal diurnal salivary cortisol profiles in middle-aged adults: associations with sleep quality and metabolic parameters

The use of saliva samples is a practical and feasible method to explore basal diurnal cortisol profiles in free-living research. This study explores a number of psychological and physiological characteristics in relation to the observed pattern of salivary cortisol activity over a 12-h period with particular emphasis on sleep. Basal diurnal cortisol profiles were examined in a sample of 147 volunteers (mean age 46.21+/-7.18 years). Profiles were constructed for each volunteer and explored in terms of the area under the curve (AUC) of the cortisol-awakening response with samples obtained immediately upon waking (0, 15, 30 and 45 min post waking) and at 3, 6, 9 and 12h post waking to assess diurnal decline. Diurnal mean of cortisol was based on the mean of cortisol at time points 3, 6, 9 and 12h post waking. Psychological measures of perceived stress and sleep were collected with concurrent biological assessment of fasting plasma glucose, insulin, blood lipids and inflammatory markers. Blunted cortisol profiles, characterised by a reduced AUC, were observed in the majority (78%) of a middle-aged sample and were associated with significantly poorer sleep quality and significantly greater waist-hip ratio (WHR). Blunted cortisol profiles were further associated with a tendency to exhibit a less favourable metabolic profile. These findings suggest that reduced cortisol secretion post waking may serve as an additional marker of psychological and biological vulnerability to adverse health outcomes in middle-aged adults.

Disentangling the effects of racial and weight discrimination on body mass index and obesity among Asian Americans

OBJECTIVES

We examined whether racial discrimination is associated with increased body mass index (BMI) and obesity among Asian Americans. Further, we explored whether this association strengthens with increasing time in the United States.

METHODS

We analyzed data from the 2002 to 2003 National Latino and Asian American Study (n=1956). Regression models tested whether reports of racial discrimination were associated with BMI and obesity, after accounting for weight discrimination, age, gender, marital status, ethnicity, generation, employment, health status, and social desirability bias (the tendency to seek approval by providing the most socially desirable response to a question).

RESULTS

We found that (1) racial discrimination was associated with increased BMI and obesity after we controlled for weight discrimination, social desirability bias, and other factors and (2) the association between racial discrimination and BMI strengthened with increasing time in the United States.

CONCLUSIONS

Racial discrimination may be an important factor related to weight gain among ethnic minorities.

Responses of the hypothalamopituitary adrenal axis and the sympathoadrenal system to isolation/restraint stress in sheep of different adiposity

There is evidence that levels of adipose tissue can influence responses of the hypothalamopituitary-adrenal (HPA) axis to stress in humans and rats but this has not been explored in sheep. Also, little is known about the sympathoadrenal responses to stress in individuals with relatively different levels of adipose tissue. We tested the hypothesis that the stress-induced activation of the HPA axis and sympathoadrenal system is lower in ovariectomized ewes with low levels of body fat (lean) than ovariectomized ewes with high levels of body fat (fat). Ewes underwent dietary manipulation for 3 months to yield a group of lean ewes (n = 7) with a mean (+/-SEM) live weight of 39.1 +/- 0.9 kg and body fat of 8.9 +/- 0.6% and fat ewes (n = 7) with a mean (+/-SEM) live weight of 69.0 +/- 1.8 kg and body fat of 31.7 +/- 3.4%. Fat ewes also had higher circulating concentrations of leptin than lean ewes. Blood samples were collected every 15 min over 8 h when no stress was imposed (control day) and on a separate day when 4 h of isolation/restraint was imposed after 4 h of pretreatment sampling (stress day). Plasma concentrations of adrenocorticotropic hormone (ACTH), cortisol, epinephrine and norepinephrine did not change significantly over the control day and did not differ between lean and fat ewes. Stress did not affect plasma leptin levels. All stress hormones increased significantly during isolation/restraint stress. The ACTH, cortisol and epinephrine responses were greater in fat ewes than lean ewes but norepinephrine responses were similar. Our results suggest that relative levels of adipose tissue influence the stress-induced activity of the hypothalamopituitary-adrenal axis and some aspects of the sympathoadrenal system with fat animals having higher responses than lean animals.

Relationship between stress, eating behavior, and obesity

Stress is thought to influence human eating behavior and has been examined in animal and human studies. Our understanding of the stress-eating relation is confounded by limitations inherent in the study designs; however, we can make some tentative conclusions that support the notion that stress can influence eating patterns in humans. Stress appears to alter overall food intake in two ways, resulting in under- or overeating, which may be influenced by stressor severity. Chronic life stress seems to be associated with a greater preference for energy- and nutrient-dense foods, namely those that are high in sugar and fat. Evidence from longitudinal studies suggests that chronic life stress may be causally linked to weight gain, with a greater effect seen in men. Stress-induced eating may be one factor contributing to the development of obesity. Future studies that measure biological markers of stress will assist our understanding of the physiologic mechanism underlying the stress-eating relation and how stress might be linked to neurotransmitters and hormones that control appetite.

Glucocorticoids and cardiovascular disease

Chronic excessive activation of glucocorticoid receptors induces obesity, insulin resistance, glucose intolerance, dyslipidaemia and hypertension. Subtle abnormalities of the hypothalamic-pituitary-adrenal axis and/or of tissue sensitivity to glucocorticoids are also associated with these cardiovascular risk factors in patients with the metabolic syndrome. Furthermore, glucocorticoids have direct effects on the heart and blood vessels, mediated by both glucocorticoid and mineralocorticoid receptors and modified by local metabolism of glucocorticoids by the 11beta-hydroxysteroid dehydrogenase enzymes. These effects influence vascular function, atherogenesis and vascular remodelling following intra-vascular injury or ischaemia. This article reviews the systemic and cardiovascular effects of glucocorticoids, and the evidence that glucocorticoids not only promote the incidence and progression of atherogenesis but also modify the recovery from occlusive vascular events and intravascular injury. The conclusion is that manipulation of glucocorticoid action within metabolic and cardiovascular tissues may provide novel therapeutic avenues to combat cardiovascular disease.

Physiological restitution after night-call duty in anaesthesiologists: impact on metabolic factors

BACKGROUND

Several studies have shown impaired mental well-being and performance in physicians work on call, but knowledge of the physiological effects is scarce. The aims of the present study were to investigate if there was a metabolic stress response in the restitutional phase after night-call duty, indicating potential negative health effects, and determine whether there were differences between physician specialities.

METHODS

Anaesthesiologists (n = 19) were compared with paediatricians/ear, nose and throat (ENT) surgeons (n = 18). On an ordinary workday, 1 and 3 days after work on night call, blood samples were taken for analysis of glucose, thyroid-stimulating hormone (TSH), free thyroxine, testosterone, insulin growth factor-1 (IGF-1), high- and low-density lipoprotein cholesterol (HDL and LDL), triglycerids (TG) and insulin. Saliva cortisol was sampled on an ordinary working day, a day including 16-h night call, the third day following, and for anaesthesiologists also on a day off work.

RESULTS

TSH differed significantly between days in both groups, with a 26% lower level 1 day after on-call duty (P < 0.001). A 48% cortisol rise in the morning preceding night duty was found for paediatricians/ENT surgeons (P < 0.01).

CONCLUSION

The significant dip in TSH level 24 h after night-call duty indicates a metabolic effect of working on night call and should be studied further. However, the levels were within the normal range and the overall results do not imply any serious metabolic changes and only minor differences were seen between specialist groups.

Recurrent intermittent restraint delays fed and fasting hyperglycemia and improves glucose return to baseline levels during glucose tolerance tests in the Zucker diabetic fatty rat--role of food intake and corticosterone

Short-term elevations of stress hormones cause an increase in glycemia. However, the effect of intermittent stress on development of type 2 diabetes mellitus is unclear. We hypothesized that recurrent intermittent restraint stress would deteriorate glycemia. Male, prediabetic Zucker diabetic fatty (ZDF) rats were restrained 1 hour per day, 5 days per week for 13 weeks and compared with unstressed, age-matched diabetic controls and lean nondiabetic rats. To differentiate the effects of recurrent restraint stress per se vs restraint-induced inhibition of food intake, a pair-fed group of rats was included. Surprisingly, recurrent restraint and pair feeding delayed fed and fasting hyperglycemia, such that they were lowered 50% by restraint and 30% by pair feeding after 13 weeks. Rats that were previously restrained or pair fed had lower glucose levels during a glucose tolerance test, but restraint further improved the return of glucose to baseline compared to pair feeding (P<.05). This was despite pair-fed rats having slightly lowered food intake and body weights compared with restrained rats. Restraint and pair feeding did not alter insulin responses to an intraperitoneal glucose tolerance test (IPGTT) or fasting insulin, and did not lower plasma lipids. Interestingly, restraint normalized basal corticosterone to one third that in control and pair-fed rats, prevented increases in pretreatment corticosterone seen with pair feeding, and led to habituation of restraint-induced corticosterone responses. After 13 weeks of treatment, multiple regression analysis showed that elevations in basal corticosterone could explain approximately 20% of the variance in fed glucose levels. In summary, intermittent restraint and its adaptations delayed hyperglycemia and improved glucose control in Zucker diabetic fatty rats. These benefits can be partially explained by restraint-induced lowering of food intake, but additional improvements compared to pair feeding may involve lower overall corticosterone exposure with repeated restraint. Paradoxically, these novel investigations suggest some types of occasional stress may limit development of diabetes.

Cortisol levels and measures of body composition in middle-aged and older men

INTRODUCTION

Similarities in the symptomatic expressions of excess adiposity and hypercortisolaemic conditions suggest that elevated glucocorticoid exposure may influence the pathogenesis of obesity. Circulating cortisol levels are not typically elevated in obese subjects, but data from large prospective samples are rare. We undertook an analysis to determine both cross-sectional and longitudinal associations between body composition and serum cortisol concentrations in a randomly chosen group of 999 community-dwelling men, aged 40-79 years.

METHODS

Data were obtained from the two follow-up waves of the Massachusetts Male Ageing Study (T2: 1995-97; T3: 2002-04). Partial correlation and multivariate regression analyses were used to estimate cross-sectional (T2) and longitudinal associations between serum cortisol concentrations and a range of measures of subjects' body composition, including weight, body mass index (BMI), waist circumference (WC), waist-to-hip girth ratio (WHR), and percentage body fat (measured by bioelectrical impedance at T3); similar analyses were conducted to assess the association between change (T2 to T3) in serum cortisol and simultaneous change in body composition parameters.

RESULTS

We observed weak negative associations between cortisol concentrations and all body composition parameters, with the exception of percentage body fat. Longitudinal results demonstrated similar relationships but associations were of lesser magnitude. T2 cortisol concentrations were not associated with change in body composition over time, whereas T2 body size was positively associated with longitudinal changes in cortisol concentrations, providing limited evidence that weight change drives changes in cortisol concentrations, rather than vice versa. Results were unchanged when age and other covariate effects were controlled.

CONCLUSIONS

Circulating cortisol concentrations are somewhat lower in obese than in nonobese community-dwelling men. There is some evidence that excess adiposity presages increases in cortisol concentrations, rather than the reverse. However, this observation should be greeted with caution, as age-related weight loss - and not gain - was associated with simultaneous increases in serum cortisol concentrations.

Massive weight loss decreases corticosteroid-binding globulin levels and increases free cortisol in healthy obese patients: an adaptive phenomenon?

OBJECTIVE

Obesity, insulin resistance, and weight loss have been associated with changes in hypothalamic-pituitary-adrenal (HPA) axis. So far, no conclusive data relating to this association are available. In this study, we aim to investigate the effects of massive weight loss on cortisol suppressibility, cortisol-binding globulin (CBG), and free cortisol index (FCI) in formerly obese women.

RESEARCH DESIGN AND METHODS

Ten glucose-normotolerant, fertile, obese women (BMI >40 kg/m2, aged 38.66 +/- 13.35 years) were studied before and 2 years after biliopancreatic diversion (BPD) when stable weight was achieved and were compared with age-matched healthy volunteers. Cortisol suppression was evaluated by a 4-mg intravenous dexamethasone suppression test (DEX-ST). FCI was calculated as the cortisol-to-CBG ratio. Insulin sensitivity was measured by an euglycemic-hyperinsulinemic clamp, and insulin secretion was measured by a C-peptide deconvolution method.

RESULTS

No difference was found in cortisol suppression after DEX-ST before or after weight loss. A decrease in ACTH was significantly greater in control subjects than in obese (P = 0.05) and postobese women (P < or = 0.01) as was the decrease in dehydroepiandrosterone (P < or = 0.05 and P < or = 0.01, respectively). CBG decreased from 51.50 +/- 12.76 to 34.33 +/- 7.24 mg/l (P < or = 0.01) following BPD. FCI increased from 11.15 +/- 2.85 to 18.16 +/- 6.82 (P < or = 0.05). Insulin secretion decreased (52.04 +/- 16.71 vs. 30.62 +/- 16.32 nmol/m(-2); P < or = 0.05), and insulin sensitivity increased by 163% (P < or = 0.0001). Serum CBG was related to BMI (r(0) = 0.708; P = 0.0001), body weight (r(0) = 0.643; P = 0.0001), body fat percent (r(0) = 0.462; P = 0.001), C-reactive protein (r(0) = 0.619; P = 0.004), and leptin (r(0) = 0.579; P = 0.007) and negatively to M value (r(0) = -0.603; P = 0.005).

CONCLUSIONS

After massive weight loss in morbidly obese subjects, an increase of free cortisol was associated with a simultaneous decrease in CBG levels, which might be an adaptive phenomenon relating to environmental changes. This topic, not addressed before, adds new insight into the complex mechanisms linking HPA activity to obesity.

Hostility and helper T-cells in patients with bulimia nervosa

OBJECTIVE

The study aimed to analyze the correlation between lymphocyte counts and several psychopathological variables associated with psychological instability (depression, hostility, impulsivity, self-defeating personality traits, and borderline personality symptoms) in patients with bulimia nervosa (BN).

METHOD

Sixty BN patients were assessed, using specific scales for eating pathology, general psychopathology, impulsivity, depression, and borderline personality features. Lymphocyte and lymphocyte subset counts were performed. Plasma cortisol at 8:00, before and after administration of 1 mg of dexamethasone at 23:00, was determined. The influence of body weight, and the use of tobacco, alcohol, and caffeine was controlled. The relationship between each isolated variable and the number of immune cells was analyzed. In a second step, supplementary post-hoc analysis of the variables was introduced to confirm the accuracy of the psychopathological assessment.

RESULTS

Hostility was negatively correlated with the number of helper T-cells (CD4+). Patients with high hostility had lower CD4+ cell counts and lower CD4+/CD8+ ratios. In the post-hoc control study, hostility was significantly related with other "interpersonal" items.

CONCLUSIONS

These results support the idea that hostility, as an expression of disturbed interpersonal relationships, could play a role as a modulator of immune activity in patients with BN.

Stress and weight change in university students in the United Kingdom

Students in the US have been shown to gain weight during their first year at university. This study examined whether students in Britain have a similar weight change during their first year at university, and tested the hypothesis that stress plays a role. A cross-sectional survey was conducted to assess stress and perceived weight change. Two hundred and sixty eight students at University College London completed the questionnaire at the end of their first year of university. On average, students reported a significant weight increase (1.53 kg+/-2.70, p<0.001), although there was considerable variation, with 55% of the sample reporting weight gain, 12% weight loss, and 33% remaining stable. Logistic regression analyses demonstrated that stress was associated with greater risk of weight gain (OR, 1.27, 95% CI, 1.12 to 1.44, p=0.001) and weight loss (1.33, 1.10 to 1.61, p=0.003), but associations were stronger among women. The associations remained unchanged after adjustment for health behaviours. Our findings confirm a modest weight gain over the first year at university, which was associated with higher levels of perceived stress in women.

Truncal distribution of fat mass, metabolic profile and hypothalamic-pituitary adrenal axis activity in prepubertal obese children

OBJECTIVE

To investigate whether truncal distribution of fat mass (TDFM) is associated with variations of the hypothalamic-pituitary-adrenocortical (HPA) axis activity in prepubertal obese children.

STUDY DESIGN

TDFM, assessed with dual energy X-ray absorptiometry and a comprehensive set of measures of HPA axis activity and reactivity have been studied in 45 prepubertal obese children aged 6 to 11 years (girls) and 6 to 13 years (boys).

RESULTS

After adjustment for whole body fat mass (%) (WBFM), TDFM correlated positively with insulin (r = 0.50, 95% CI [0.23; 0.70]) and homeostasis model assessment of insulin resistance (r = 0.52, 95% CI [0.25; 0.71]). When adjusted for WBFM, TDFM correlated positively with morning plasma cortisol (r = 0.38, 95% CI [0.15; 0.64]) in the total population. TDFM correlated negatively with the rise of salivary cortisol after a standard meal (r = -0.43, 95% CI [-0.71; -0.02]), obviously in girls. When adjusted for WBFM and TDFM, morning plasma cortisol correlated positively with total cholesterol (r = 0.41, 95% CI [0.11; 0.65]) and triglyceride (r = 0.44, 95% CI [0.14; 0.67]). The rise of salivary cortisol after a standard meal was negatively (r = -0.56, 95% CI [-0.85; -0.01]) and positively (r = 0.74, 95% CI [0.16; 0.94]) correlated with homeostasis model assessment of insulin resistance in boys and girls, respectively.

CONCLUSIONS

Association exists in prepubertal obese children between TDFM and markers of HPA axis activity. These data suggest that HPA axis could be involved early in life in obesity associated with pejorative metabolic profile.

Study of substance P and its receptor neurokinin-1 in psoriasis and their relation to chronic stress and pruritus

Substance P and its receptor(R) neurokinin (NK)-1 may have a role in the pathogenesis of psoriasis. Stress has been reported to play a role in the onset and exacerbation of psoriasis, which might include the substance P-NK-1 receptor(R) pathway. A feature of psoriasis, that has been correlated to the severity of stress and secretion of substance P, is pruritus. The objective of this study was to investigate the expression of substance P and the NK-1R in involved and noninvolved psoriatic skin, using a biotinylated streptavidin technique. Moreover, a possible correlation between the patient s level of chronic stress, measured by salivary cortisol samples, degree of lesional pruritus, measured by means of a visual analogue scale, and the expression of substance P- and the NK-1R, was investigated. There was a low number of substance P positive nerve fibres in noninvolved and involved skin, the major immunoreactivity for substance P being found in inflammatory cells. The number of substance P- and NK-1R positive inflammatory cells was increased in involved compared to noninvolved psoriatic skin. The substance P positive cells were mostly lymphocytes, while most of the NK-1R positive cells were mast cells. NK-1R immunoreactivity was also seen as a reticular pattern in the upper part of the epidermis of involved skin in the majority of the patients. Low cortisol ratios in the patients, being an indicator of chronic stress, were correlated to an increased number of substance P- and NK-1R positive inflammatory cells in noninvolved psoriatic skin, and higher cortisol ratios to the presence of keratinocyte NK-1R immunoreactivity in involved skin. The degree of pruritus could not be correlated to the number of substance P positive fibers nor cells. Nonneuronal substance P and its receptor NK-1 might have a role in psoriasis, also during chronic stress.

Obesity-related sleepiness and fatigue: the role of the stress system and cytokines

Obesity has epidemic proportions in Western societies and, because of its significant association with morbidity and mortality, is a major public health issue. Excessive daytime sleepiness (EDS) and fatigue (tiredness without increased sleep propensity)--which have been associated with obesity--have a significant impact on individual well-being and public safety. In this article, we review data that challenge the belief that sleep apnea and sleep disruption per se are the primary determinants of obesity-related daytime sleepiness and fatigue. Specifically, it appears that obesity per se is associated with objective and subjective daytime sleepiness compared to normal-weight controls regardless of sleep apnea and sleep loss. Indeed, obese patients without sleep apnea are sleepier compared to nonobese controls whereas within the morbidly obese, those who have high sleep efficiency at night are sleepier than those who have low sleep efficiency. In addition, in recent studies based on large random samples of the general population, the primary determinants of subjective EDS were depression and metabolic disturbances, that is, obesity/diabetes, and not sleep apnea or objective sleep disruption. Furthermore, sleepiness and fatigue are very prevalent in conditions associated with insulin resistance, for instance, the polycystic ovary syndrome (PCOS), independently of sleep apnea or obesity, or in conditions of insufficient physical activity. On the basis of these data, we propose that obesity-related objective daytime sleepiness and fatigue are associated primarily with metabolic and psychological factors and less with sleep apnea and sleep disruption per se. Furthermore, we suggest that objective sleepiness is primarily related to metabolic factors, whereas fatigue appears to be related to psychological distress. Finally, based on data from studies in normal controls and patients with sleep disorders, we propose that the interaction of the hypothalamic-pituitary-adrenal (HPA) axis and proinflammatory cytokines determines the level of sleep/arousal within the 24-h cycle, that is, "hypercortisolemia" plus hypercytokinemia is associated with low sleep efficiency and fatigue, whereas "eucortisolemia" or "hypocortisolemia" plus hypercytokinemia is associated with high sleep efficiency and objective sleepiness.

Stress, the endoplasmic reticulum, and insulin resistance

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.

High anticipatory stress plasma cortisol levels and sensitivity to glucocorticoids predict severity of coronary artery disease in subjects undergoing coronary angiography

Hyperactivity of the hypothalamic-pituitary-adrenal (HPA) axis and/or increased sensitivity of peripheral tissues to glucocorticoids may be associated with the dysmetabolic syndrome and its cardiovascular sequelae. In this prospective pilot clinical study, we examined possible associations between HPA axis activity and severity of cardiovascular disease. We measured morning serum cortisol and intima media thickness (IMT) of carotid and femoral arteries in 105 subjects before undergoing coronary angiography for suspected coronary artery disease (CAD). In a randomly selected 46 of these subjects, we obtained late afternoon and morning cortisol levels (after ultralow-dose dexamethasone [0.25 mg] treatment) and determined their genotype for the Bcl1 polymorphism of the glucocorticoid receptor gene, which has been associated with increased sensitivity to glucocorticoids. There was significant association between morning preangiography cortisol levels and the number of vessels with severe stenosis in the angiography, independently of age or sex (P = .002), and a trend for a positive correlation between morning cortisol and the IMT of the femoral artery (P = .057). Bcl1 G allele homozygotes had a significantly higher carotid IMT (P = .005) and a nonsignificant tendency for higher waist-hip ratio (P = .059). Hyperactivity of the HPA axis in anticipation of a stressful procedure, such as angiography, may be an index of CAD severity. Chronic HPA axis hyperreactivity combined with tissue hypersensitivity to glucocorticoids may contribute to more severe atherosclerosis and CAD.

Cortisol secretary pattern and glucocorticoid feedback sensitivity in women from a Mediterranean area: relationship with anthropometric characteristics, dietary intake and plasma fatty acid profile

BACKGROUND

Chronic stress is associated with a dysfunctional hypothalamic-pituitary-adrenal (HPA) axis consisting on disturbances on the cortisol response and lipid metabolism.

OBJECTIVE

To evaluate the HPA axis activity in women from a Mediterranean area, comparing three different measurements: daily cortisol secretory variability, postprandial cortisol secretion and glucocorticoid feedback sensitivity. In addition, HPA axis disturbance is correlated with dietary habits and plasma fatty acid profiles.

DESIGN

The participants were 41 women born during the first 6 months of 1960 and living in a Mediterranean area (Murcia, Spain). They were of normal weight, with a waist circumference of 80.5 +/- 9.3 cm. Their salivary cortisol levels, 7-day dietary record and plasma fatty acid profile were evaluated. Daily cortisol variability and postlunch cortisol secretion were recorded and a dexamethasone suppression test is performed in order to detect possible HPA disturbance.

RESULTS

Both the methods used for HPA axis evaluation were positively correlated (r = 0.448, P = 0.004). Subjects with normal diurnal curves (high cortisol variability) showed significantly higher cortisol values in the morning and postprandial cortisol secretion than women with pathological curves (medium and low variability). Cortisol variability was inversely correlated with waist circumference (r = -0.312, P = 0.047), suggesting that a disturbed HPA axis response may lead to an android pattern of body fat distribution. Dietary fat and saturated fatty acid intake were lower in the high cortisol variability group, while monounsaturated fatty acid intake was higher (P < 0.05). No major differences were reported in plasma fatty acid profile.

CONCLUSIONS

A disturbed HPA axis is associated with abdominal fat distribution and a higher content of fat and saturated fatty acids in the diet. Women who chose a dietary pattern closer to the Mediterranean diet, with high monounsaturated fatty acid intake, showed lower levels on HPA axis disturbance.

Awakening cortisol response in lean, obese, and reduced obese individuals: effect of gender and fat distribution

OBJECTIVE

Our goal was to assess the awakening cortisol response (ACR) in obese and reduced obese men and women.

RESEARCH METHODS AND PROCEDURES

Fifty-one men (16 lean, 19 abdominally obese, and 16 reduced obese) and 31 women (12 lean, 10 subcutaneously obese, and 9 reduced obese) were selected to participate to this study. Strict ranges of BMI and waist circumference were used to select the participants. Medical examination, psychological assessment, anthropometric measurements, and blood sampling were undergone at the laboratory. Cortisol response to awakening was determined with saliva cortisol sampling being taken immediately at the time of awakening and 30 minutes thereafter over 3 days within a period of 2 months.

RESULTS

Men with visceral obesity exhibited an enhanced ACR, whereas this response tends to return to normal in a reduced obese state. In women, peripheral fat accumulation does not modify ACR, but weight loss increased the response.

DISCUSSION

These results highlight gender effects on ACR of obese and reduced obese subjects, which could be accounted for by the different fat distribution profiles that characterize men and women. They also provide further support for the usefulness of ACR in assessing the hypothalamic-pituitary-adrenal axis activity status.

Does binge eating disorder alter cortisol secretion in obese women?

It is still poorly determined whether the presence of Binge Eating Disorder (BED) would alter cortisol secretion in obese patients. We aimed at investigating levels of salivary cortisol (SC) in patients with and without BED. Forty seven (47) obese women between 30 and 65 years old were sequentially selected to participate in the study. The diagnosis of BED was assessed according to the Structured Clinical Interview for DSM-IV. Binge Eating Scale (BES) was used to assess binge severity. A trend toward a negative correlation was observed between SC and body mass index in the whole sample (p=0.06). The presence of BED was not associated with increased levels of SC. In women without BED, SC levels correlated inversely with BMI (p=0.01). On the other hand, in women with BED, SC levels correlated significantly with BES (p=0.01). Although obesity is associated with decreased levels of cortisol, this relationship may be lost in patients with BED. In patients with BED, binge eating severity may be a more relevant regulator of cortisol secretion than obesity itself.

Metabolic syndrome in women with chronic pain

Fibromyalgia is a prevalent syndrome characterized by chronic pain, fatigue, and insomnia. Patients with fibromyalgia commonly have an elevated body mass index and are physically inactive, 2 major risk factors for metabolic syndrome. Yet little is known about the relationship between chronic pain conditions and metabolic disturbances. Our study evaluated the risk for, and neuroendocrine correlates of, metabolic syndrome in this patient population. Women with fibromyalgia (n = 109) were compared with control healthy women (n = 46), all recruited from the community. Metabolic syndrome was identified by using criteria from the Adult Treatment Panel III with glycosylated hemoglobin concentrations substituted for serum glucose. Catecholamine and cortisol levels were determined from 12-hour overnight urine collections. Women with fibromyalgia were 5.56 times more likely than healthy controls to have metabolic syndrome (95% confidence interval, 1.25-24.74). Fibromyalgia was associated with larger waist circumference (P = .04), higher glycosylated hemoglobin (P = .01) and serum triglyceride (P < .001) levels, and higher systolic (P = .003) and diastolic (P = .002) blood pressure. Total and low-density lipoprotein cholesterol were also significantly higher in women with fibromyalgia (P = .001 and .02, respectively), although high-density lipoprotein cholesterol was in the reference range. These associations were not accounted for by age or body mass index. Meeting criteria for more metabolic syndrome components was related to higher urinary norepinephrine (NE)/epinephrine and NE/cortisol ratios (P < .001 and P = .009, respectively). Women with chronic pain from fibromyalgia are at an increased risk for metabolic syndrome, which may be associated with relatively elevated NE levels in conjunction with relatively reduced epinephrine and cortisol secretion.

Peroxisome proliferator-activated receptor-alpha and glucocorticoids interactively regulate insulin secretion during pregnancy

We evaluated the impact of peroxisome proliferator-activated receptor (PPAR)alpha activation and dexamethasone treatment on islet adaptations to the distinct metabolic challenges of fasting and pregnancy, situations where lipid handling is modified to conserve glucose. PPARalpha activation (24 h) in vivo did not affect glucose-stimulated insulin secretion (GSIS) in nonpregnant female rats in the fasted state, although fasting suppressed GSIS. Dexamethasone treatment (5 days) of nonpregnant rats lowered the glucose threshold and augmented GSIS at high glucose; the former effect was selectively opposed by PPARalpha activation. Pregnancy-induced changes in GSIS were opposed by PPARalpha activation at day 19 of pregnancy. Dexamethasone treatment from day 14 to 19 of pregnancy did not modify the GSIS profile of perifused islets from 19-day pregnant rats but rendered the islet GSIS profile refractory to PPARalpha activation. During sustained hyperglycemia in vivo, dexamethasone treatment augmented GSIS in nonpregnant rats but limited further modification of GSIS by pregnancy. We propose that the effect of PPARalpha activation to oppose lowering of the glucose threshold for GSIS by glucocorticoids is important as part of the fasting adaptation, and modulation of the islet GSIS profile by glucocorticoids toward term facilitates the transition of maternal islet function from the metabolic demands of pregnancy to those imposed after parturition.

Fetal Origins of Stress-Related Adult Disease

During the past decade, a considerable body of evidence has emerged showing that circumstances during the fetal period may have lifelong programming effects on different body functions with a considerable impact on disease susceptibility. The purpose of this article is to provide a synopsis of these findings and their role in explaining the development of stress-related adult disease. In the context of Per Björntorp memorial symposium, stress-related disease will be interpreted broadly, including cardiovascular disease and components of the metabolic syndrome, for which the evidence of fetal origins is most abundant. It has however become evident that early-life programming has a much broader potential effect on an individual's health. For example, perinatal variables, such as low birth weight, have been associated with increased prevalence of depressive symptoms. Mechanistic studies in animals and humans have shown that lifelong programming of the hypothalamic-pituitary-adrenal axis (HPAA) function by fetal life conditions is likely to be a key factor in mediating associations with these disorders, which frequently are characterized by HPAA overactivity. Preliminary observations suggest a similar important role for early-life programming of sympathoadrenal function. Reduced HPAA activity is characteristic of a number of stress-related disorders, including posttraumatic stress disorder; chronic pain; fatigue; and atypical, melancholic depression. It is therefore highly plausible that susceptibility to these disorders originates in a similar manner during early life, although direct evidence is to a great deal lacking. Important targets for future research include distinction between the effects of different pregnancy conditions, such as maternal malnutrition, preeclampsia, and maternal infection, which may have dissimilar late-life consequences. This will be a crucial step when the associations that are currently emerging will be translated into disease prevention.

The Hypothalamic-Pituitary-Adrenal Axis Activity in Obesity and the Metabolic Syndrome

A hypothetical role of glucocorticoids in human obesity has been suggested since the abdominal obesity phenotype and syndromes of endogenous or exogenous hypercortisolism share several clinical, metabolic, and cardiovascular similarities. An emerging body of evidence indicates that both neuroendocrine dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis as well as peripheral alterations of cortisol metabolism may play a role in the pathophysiology of abdominal obesity. Major alterations of the HPA axis in vivo may be identified in different ways. They include evaluation of hormone concentrations: (a) in basal conditions, in blood, urine, or saliva samples; (b) during dynamic studies following stimulation with different neuropeptides or psychological stress challenges, or suppression with inhibiting agents of the HPA axis at different levels; and (c) after mixed meals or meals containing different nutrient compositions. In addition, alteration of peripheral cortisol metabolism can be detected by direct measurement of cortisol metabolites in urine, although this is a matter of more complex investigation. Alterations of the HPA axis in abdominal obesity are associated with insulin resistance, which suggests a direct responsibility of these hormonal alterations in the susceptibility of affected patients to develop both metabolic and cardiovascular diseases. According to available data, no single marker probably has the power to detect subtle alterations of the HPA axis in conditions, such as the abdominal obesity and the metabolic syndrome. On the contrary, they indicate the need for multiple parameters. At present, evaluation of urinary free cortisol, particularly during the night-time, and salivary-free cortisol appear to be promising for these purposes, whereas dynamic tests should be reserved for specific clinical settings, involving well-characterized patients.

Neuroendocrine mechanisms of innate states of attenuated responsiveness of the hypothalamo-pituitary adrenal axis to stress

Neuroendocrine responses to stress vary between sexes and reproductive states and are influenced by the type of stressor. Stress responses are attenuated in some physiological states, such as lactation and conditions of low visceral adipose tissue. Moreover, some individuals within a species characteristically display reduced stress responses. The neuroendocrine mechanisms for stress hyporesponsiveness are likely to include reduced synthesis and secretion of corticotropin releasing hormone (CRH) and arginine vasopressin (AVP) from the hypothalamus as a result of enhanced glucocorticoid negative feedback and/or reduced noradrenergic stimulatory input from the brain stem. A major limitation of research to date is the lack of direct measures of CRH and AVP secretion. Attenuated stress responsiveness is also commonly associated with reduced pituitary responsiveness to CRH and AVP. The possible roles of inhibitory central inputs to CRH and AVP neurons and of oxytocin and prolactin in attenuating the HPA axis responses to stress are unknown.

Burnout and risk of cardiovascular disease: evidence, possible causal paths, and promising research directions

Burnout is characterized by emotional exhaustion, physical fatigue, and cognitive weariness, resulting from prolonged exposure to work-related stress. The authors review the accumulated evidence suggesting that burnout and the related concept of vital exhaustion are associated with increased risk of cardiovascular disease and cardiovascular-related events. The authors present evidence supporting several potential mechanisms linking burnout with ill health, including the metabolic syndrome, dysregulation of the hypothalamic-pituitary-adrenal axis along with sympathetic nervous system activation, sleep disturbances, systemic inflammation, impaired immunity functions, blood coagulation and fibrinolysis, and poor health behaviors. The association of burnout and vital exhaustion with these disease mediators suggests that their impact on health may be more extensive than currently indicated.

Relationship Between the Cardiometabolic Syndrome and Obstructive Sleep Apnea

Obstructive sleep apnea (OSA), characterized by cessation of air flow for a minimum of 10 seconds despite continuous respiratory effort, is a prevalent condition in our society. Recent studies demonstrate that OSA is an independent risk factor for insulin resistance and the cardiometabolic syndrome. Hypoxemia and sleep fragmentation from OSA appear to produce autonomic activation, alterations in neuroendocrine function, and increased amounts of inflammatory cytokines (interleukin 6 and tumor necrosis factor alpha). These variables have important roles in the pathogenesis of insulin resistance and the cardiometabolic syndrome. It can be concluded that insulin sensitivity, a key contributor to the pathogenesis of the cardiometabolic syndrome, is mainly determined by the extent of obesity and, to a lesser extent, by OSA. The authors review OSA and summarize recent discoveries and proposed mechanisms of the causal relationship that OSA has with insulin resistance and the cardiometabolic syndrome independent of many confounding comorbidities.

Differences in cortisol concentrations in South Asian and European men living in the United Kingdom

OBJECTIVE

The metabolic syndrome is more prevalent in South Asians in Britain than in the general population. Furthering our understanding of the underlying mechanisms is important because of the increased risk of cardiovascular disease associated with the metabolic syndrome. As it has been proposed that increased activity of the hypothalamic pituitary adrenal axis might underlie the metabolic syndrome, we hypothesized that plasma cortisol levels would be higher in South Asians and that increased cortisol levels would be associated with cardiovascular risk factors comprising the metabolic syndrome. The aim of the study was to examine ethnic differences in cortisol levels and to compare the relationships between cortisol levels and cardiovascular risk factors in men from different ethnic groups.

DESIGN

Cross-sectional population-based study, Newcastle upon Tyne, UK. (Newcastle Heart project). Participants One hundred men, 40-67 years old, of European and South Asian (Indian, Pakistani, Bangladeshi) ancestry, with and without cardiovascular risk factors of the metabolic syndrome.

MEASUREMENTS

Measurement of plasma cortisol and corticosteroid binding globulin in stored sera.

RESULTS

After adjustment for age and the presence of cardiovascular risk factors, mean cortisol was 27% (95% CI, 10%, 40%) lower in South Asians compared to Europeans. Cortisol levels were higher in all men with cardiovascular risk factors than those without.

CONCLUSIONS

Cortisol levels are lower in South Asian than in European men resident in the UK. Despite lower cortisol levels in South Asians, the relations between cortisol and cardiovascular risk factors remain strong.

Dyslipidemia in Industrial Workers in Hot Environments

The aim of the study was to follow the rate and manifestation of dyslipidemia in industrial workers exposed to heat. One hundred and two male industrial workers exposed to heat and a control group of 102 male workers were studied. The microclimate components were followed and Wet Bulb Globe Temperature (WBGT) was calculated. The mean WGBT was 35.4 degrees C (28.4-41.7 degrees C) for the studied heat exposed work places. The lipid indices: total cholesterol (TC), high density lipoprotein cholesterol (HDL-C), low density lipoprotein cholesterol (LDL-C) and triacylglycerols were assayed with enzymatic tests. TC/HDL-C ratio was calculated, too. Arterial pressure, anthropometric variables, smoking, alcohol use were followed and no significant differences between the studied groups were found. Significantly higher TC, LDL-C and TC/HDL-C were found with the heat exposed industrial workers. Odds ratio indicated higher risk in heat exposed industrial workers of becoming dyslipidemic [for TC OR = 1.481 (1.097-2.002) and for LDL-C OR = 1.539 (1,123-2.111)]. Regular screening of lipid profile in heat exposed workers is recommended.

Cardiovascular risk in operators under radiofrequency electromagnetic radiation

The aim of the study was to assess the long-term effects of radiofrequency electromagnetic radiation (EMR) on the cardiovascular system. Two groups of exposed operators (49 broadcasting (BC) station and 61 TV station operators) and a control group of 110 radiorelay station operators, matched by sex and age, with similar job characteristics except for the radiofrequency EMR were studied. The EMR exposure was assessed and the time-weighted average (TWA) was calculated. The cardiovascular risk factors arterial pressure, lipid profile, body mass index, waist/hip ratio, smoking, and family history of cardiovascular disease were followed. The systolic and diastolic blood pressure (SBP and DBP), total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-C) were significantly higher in the two exposed groups. It was found that the radiofrequency EMR exposure was associated with greater chance of becoming hypertensive and dyslipidemic. The stepwise multiple regression equations showed that the SBP and TWA predicted the high TC and high LDL-C, while the TC, age and abdominal obesity were predictors for high SBP and DBP. In conclusion, our data show that the radiofrequency EMR contributes to adverse effects on the cardiovascular system.

The Buffalo Cardio-Metabolic Occupational Police Stress (BCOPS) Pilot Study: Methods and Participant Characteristics

PURPOSE

The Buffalo Cardio-Metabolic Occupational Police Stress (BCOPS) study is one of the first population-based studies to integrate psychological, physiological, and subclinical measures of stress, disease, and mental dysfunction. This pilot study was undertaken to establish a methodology and descriptive results for a larger police study.

METHODS

A stratified sample of 100 officers was randomly selected from the Buffalo, NY Police Department. Salivary cortisol served as a stress biomarker. Flow mediated dilation (FMD) and carotid intima-media thickness (IMT) were performed with ultrasound. Dual Energy X-Ray Absorptiometry (DEXA) and anthropometric measures assessed body composition. Self-report measures of depression and posttraumatic stress disorder (PTSD) were obtained.

RESULTS

Recruitment attained for the study was 100%. Seventy-five percent showed a cortisol increase upon awakening, 90% a negative diurnal slope, and 77% an increased cortisol response after a high protein lunch challenge. Dexamethasone suppression was evident. FMD showed an increase in mean brachial artery diameter of 3.2% in men and 3.9% in women, and mean IMT was lower (male=0.67 mm; female=0.62 mm) compared to populations of similar age. For males, the mean body-mass index (BMI) was 29.8 kg/m2 and total body fat 23.4%. For females, the mean BMI was 26.7 kg/m2 and total body fat 31.5%. For all officers, 16% met criteria for depression; 36% reported elevated PTSD symptoms.

CONCLUSIONS

Compared to populations of similar age, police officers had slightly lower FMD, lower carotid IMT, elevated BMI, and higher reported rates of depression and PTSD. Standardized physiological and psychological data collection and descriptive results confirmed that the methodology of the study is feasible in a working police population.

[Corticotropic axis and chronic stress in abdominal obesity and metabolic syndrome]

Several indicators of corticotropic axis hyperactivity have been observed in common abdominal obesity, which is clinically similar to the obesity found in Cushing's syndrome. Corticotropic axis hyperactivity may be involved in the development and metabolic and cardiovascular complications of abdominal obesity. Several mechanisms may be responsible for this hormonal dysregulation: genetic, lifestyle, and nutritional factors, and chronic stress. We note the necessity of methodologically-impeccable clinical studies for an objective evaluation of the role of stress in obesity.

Rheumatoid arthritis: a disease associated with accelerated atherogenesis

OBJECTIVES

Rheumatoid arthritis (RA) is a systemic inflammatory disease associated with an increased prevalence of coronary heart disease and a high cardiovascular (CV) mortality. In this article, a review of mechanisms implicated in the development of accelerated atherogenesis in RA was performed. The potential role of treatment to reduce the incidence of CV events in RA was also discussed.

METHODS

Retrospective review of the literature. The potential mechanisms implicated in the development of accelerated atherogenesis in RA, information on carotid ultrasonography, and the potential implication of treatment to prevent accelerated atherogenesis in individuals with RA were examined.

RESULTS

Endothelial dysfunction, which is an early step in the development of atherosclerosis, has been observed in patients with RA. Deleterious effects resulting from persistent chronic inflammation may lead to endothelial dysfunction, insulin resistance, and a dyslipidemic pattern in these patients. Other mechanisms different from those related to classic atherogenesis risk factors, such as hyperhomocysteinemia and increased oxidative stress, are considered to be implicated in the pathogenesis of atherosclerosis in RA. Increased carotid intima-media thickness and carotid plaques have been found in RA patients compared with matched controls. Active MTX treatment of the disease has been associated with decreased CV mortality. Additional drugs such as statins may be considered in the management of these patients.

CONCLUSIONS

The increased prevalence of CV mortality rate in RA cannot only be explained by the presence of traditional atherosclerotic risk factors. A chronic inflammatory response may promote the development of accelerated atherogenesis in these patients. Active treatment of the disease is required to reduce the risk of developing CV complications in individuals with RA.

Central adiposity is associated with cardiovascular reactivity to stress in adolescents

The current study examined the association between central adiposity, measured by waist circumference, and cardiovascular reactivity to stress among 106 White and 105 Black adolescents, approximately 50% of whom were girls. Participants engaged in 4 laboratory tasks while cardiovascular reactivity measures were taken. Independent of body mass index, race, and gender, participants with a greater waist circumference exhibited greater systolic blood pressure reactivity and diastolic blood pressure reactivity (boys only). Race did not affect the results. Results from the present study suggest that central adiposity is associated with blood pressure reactivity early in life, especially in adolescent boys.

Sleep apnea is a manifestation of the metabolic syndrome

Obstructive sleep apnea (OSA) is a prevalent disorder particularly among middle-aged, obese men, although its existence in women as well as in lean individuals is increasingly recognized. Despite the early recognition of the strong association between OSA and obesity, and OSA and cardiovascular problems, sleep apnea has been treated as a 'local abnormality' of the respiratory track rather than as a 'systemic illness.' In 1997, we first reported that the pro-inflammatory cytokines interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNFalpha) were elevated in patients with disorders of excessive daytime sleepiness (EDS) and proposed that these cytokines were mediators of daytime sleepiness. Also, we reported a positive correlation between IL-6 or TNFalpha plasma levels and the body-mass-index (BMI). In subsequent studies, we showed that IL-6, TNFalpha, and insulin levels were elevated in sleep apnea independently of obesity and that visceral fat, was the primary parameter linked with sleep apnea. Furthermore, our findings that women with the polycystic ovary syndrome (PCOS) (a condition associated with hyperandrogenism and insulin resistance) were much more likely than controls to have sleep disordered breathing (SDB) and daytime sleepiness, suggests a pathogenetic role of insulin resistance in OSA. Other findings that support the view that sleep apnea and sleepiness in obese patients may be manifestations of the Metabolic Syndrome, include: obesity without sleep apnea is associated with daytime sleepiness; PCOS and diabetes type 2 are independently associated with EDS after controlling for SDB, obesity, and age; increased prevalence of sleep apnea in post-menopausal women, with hormonal replacement therapy associated with a significantly reduced risk for OSA; lack of effect of continuous positive airway pressure (CPAP) in obese patients with apnea on hypercytokinemia and insulin resistance indices; and that the prevalence of the metabolic syndrome in the US population from the Third National Health and Nutrition Examination Survey (1988-1994) parallels the prevalence of symptomatic sleep apnea in general random samples. Finally, the beneficial effect of a cytokine antagonist on EDS in obese, male apneics and that of exercise on SDB in a general random sample, supports the hypothesis that cytokines and insulin resistance are mediators of EDS and sleep apnea in humans. In conclusion, accumulating evidence provides support to our model of the bi-directional, feed forward, pernicious association between sleep apnea, sleepiness, inflammation, and insulin resistance, all promoting atherosclerosis and cardiovascular disease.

Maternal body composition, offspring blood pressure and the hypothalamic-pituitary-adrenal axis

We tested the hypothesis that women who are thin or have poor pregnancy weight gain have offspring with higher blood pressure and examined whether this link is mediated by increased secretion of cortisol. We studied a cohort of 388 children born in Kingston, Jamaica. From hospital records we obtained information about their mother's body mass index (BMI) and weight gain during pregnancy. At age 8.5 years we measured the children's fasting plasma cortisol concentrations and blood pressure and assessed their mother's anthropometry. There were no relationships between the mother's BMI or weight gain during pregnancy and offspring blood pressure. However, mothers with a greater subscapular to triceps skinfold thickness ratio (SSTR) had offspring with higher blood pressure (5.6 mmHg systolic and 3.7 mmHg diastolic increase per unit change in SSTR, P = 0.002 and P = 0.008 respectively). Fasting plasma cortisol concentrations correlated with the children's systolic (r = 0.33, P < 0.0001) and diastolic pressures (r = 0.12, P = 0.02) independently of age, gender, weight or socio-economic status and were also predicted by the mother's SSTR. These findings suggest that maternal truncal obesity rather than thinness is associated with raised blood pressure in the offspring, and that this link may be mediated by increased cortisol secretion.

Is the association between socioeconomic position and coronary heart disease stronger in women than in men?

The association between socioeconomic position and health is generally believed to be weaker among women than men. However, gender differences in the relation between socioeconomic position and coronary heart disease have not been evaluated in a representative sample of the US population. The authors examined this association in the First National Health and Nutrition Examination Survey (1971-1993), a longitudinal, representative study of the US population (n = 6,913). Information on educational attainment, household income, and covariates was derived from the baseline interview, and that on incident coronary heart disease was obtained from hospital records/death certificates over 22 years of follow-up. Cox's proportional hazards models showed that education and income were inversely associated with incident coronary heart disease in age-only and multivariate models. Risk associated with education varied by gender (p = 0.01), with less than high school education associated with stronger risk of coronary heart disease in women (relative risk = 2.15, 95% confidence interval: 1.46, 3.17) than in men (relative risk = 1.58, 95% confidence interval: 1.18, 2.12) in age-adjusted models. Low education was associated with greater social and psychological risks for women than men; however, metabolic risks largely explained gender differences in the educational gradient in coronary heart disease.