Is metabolic syndrome a mild form of Cushing's syndrome?

Melatonin prevents early pituitary dysfunction induced by sucrose-rich diets

While physiological levels of glucocorticoids are required to ensure proper functions of the body, consistently high levels may engender several deleterious consequences. We have previously shown an increase in the activity of the hypothalamic-pituitary-adrenal (HPA) axis in rats fed sucrose-rich diets (SRD). The main goal of this study was to analyze the processes involved in the modulation of the pituitary production of ACTH by SRD, and to test melatonin as a possible therapeutic agent for the prevention of the HPA axis dysfunction. Male Wistar rats were fed standard chow and either SRD (30% sucrose in the drinking water) or plain water for three weeks. Melatonin was administered as subcutaneous pellets. Results showed that SRD treatment induced an increase in systemic ACTH and corticosterone levels and a decrease in melatonin levels. In the pituitary gland, we also detected an increase in the expression levels of proopiomelanocortin (POMC) that was accompanied by increased levels of: lipoperoxides, nitro-tyrosine modified proteins, catalase, heme oxygenase-1, interleukin-1β mRNA, and by an increase in the tissue number of inflammatory cells (F4/80 and Iba-1 positive cells). Melatonin treatment prevented all these systemic and pituitary changes as well as the increase in POMC expression induced by incubation of AtT-20 corticotrophs with conditioned media obtained from stimulated macrophages. In conclusion, stimulation of POMC/ACTH production in rats fed a SRD could involve the generation of oxidative stress and inflammation in the pituitary gland. Melatonin treatment prevented these effects and normalized the activity of the HPA axis.

Should Cushing's Syndrome be Considered as a Disease with High Cardiovascular Risk in Relevant Guidelines?

A considerable amount of data supports a 1.8-7.4-fold increased mortality associated with Cushing's syndrome (CS). This is attributed to a high occurrence of several cardiovascular disease (CVD) risk factors in CS [e.g. adiposity, arterial hypertension (AHT), dyslipidaemia and type 2 diabetes mellitus (T2DM)]. Therefore, practically all patients with CS have the metabolic syndrome (MetS), which represents a high CVD risk. Characteristically, despite a relatively young average age, numerous patients with CS display a 'high' or 'very high' CVD risk (i.e. risk of a major CVD event >20% in the following 10 years). Although T2DM is listed as a condition with a high CVD risk, CS is not, despite the fact that a considerable proportion of the CS population will develop T2DM or impaired glucose tolerance. CS is also regarded as a risk factor for aortic dissection in current guidelines. This review considers the evidence supporting listing CS among high CVD risk conditions.

Glucocorticoids suppress GLP-1 secretion: possible contribution to their diabetogenic effects

Evidence indicates that subtle abnormalities in GC (glucocorticoid) plasma concentrations and/or in tissue sensitivity to GCs are important in the metabolic syndrome, and it is generally agreed that GCs induce insulin resistance. In addition, it was recently reported that short-term exposure to GCs reduced the insulinotropic effects of the incretin GLP-1 (glucagon-like peptide 1). However, although defective GLP-1 secretion has been correlated with insulin resistance, potential direct effects of GCs on GLP-1-producing L-cell function in terms of GLP-1 secretion and apoptosis have not been studied in any greater detail. In the present study, we sought to determine whether GCs could exert direct effects on GLP-1-producing L-cells in terms of GLP-1 secretion and cell viability. We demonstrate that the GR (glucocorticoid receptor) is expressed in GLP-1-producing cells, where GR activation in response to dexamethasone induces SGK1 (serum- and glucocorticoid-inducible kinase 1) expression, but did not influence preproglucagon expression or cell viability. In addition, dexamethasone treatment of enteroendocrine GLUTag cells reduced GLP-1 secretion induced by glucose, 2-deoxy-D-glucose, fructose and potassium, whereas the secretory response to a phorbol ester was unaltered. Furthermore, in vivo administration of dexamethasone to rats reduced the circulating levels of GLP-1 concurrent with induction of insulin resistance and glucose intolerance. We can conclude that GR activation in GLP-1-producing cells will diminish the secretory responsiveness of these cells to subsequent carbohydrate stimulation. These effects may not only elucidate the pathogenesis of steroid diabetes, but could ultimately contribute to the identification of novel molecular targets for controlling incretin secretion.

Metabolic abnormalities in pituitary adenoma patients: a novel therapeutic target and prognostic factor

Metabolic abnormalities are common in cancers, and targeting metabolism is emerging as a novel therapeutic approach to cancer management. Pituitary adenoma (PA) is a type of benign tumor. Impairment of tumor cells' metabolism in PA seems not to be as apparent as that of other malignant tumor cells; however, aberrant hormone secretion is conspicuous in most PAs. Hormones have direct impacts on systemic metabolism, which in turn, may affect the progression of PA. Nowadays, conventional therapeutic strategies for PA do not include modalities of adjusting whole-body metabolism, which is most likely due to the current consideration of the aberrant whole-body metabolism of PA patients as a passive associated symptom and not involved in PA progression. Because systemic metabolic abnormalities are presented by 22.3%-52.5% PA patients and are closely correlated with disease progression and prognosis, we propose that assessment of metabolic status should be emphasized during the treatment of PA and that control of metabolic abnormalities should be added into the current therapies for PA.

Short-term, low-dose GH therapy improves insulin sensitivity without modifying cortisol metabolism and ectopic fat accumulation in adults with GH deficiency

CONTEXT

Low-dose GH (LGH) therapy has been reported to improve insulin sensitivity in GH-deficient adults; however, the mechanism is unclear.

HYPOTHESIS

Effects of LGH therapy on insulin sensitivity are mediated through changes in cortisol metabolism and ectopic fat accumulation.

DESIGN AND SETTING

This was a double-blind, placebo-controlled, parallel, 3-month study.

PARTICIPANTS AND INTERVENTION

Seventeen GH-deficient adults were randomized to receive either daily LGH or placebo injections. Fasting blood samples were collected at baseline, and months 1 and 3, whereas hyperinsulinemic-euglycemic clamps, magnetic resonance spectroscopy scans, 24-hour cortisol production rates (CPRs), and sc abdominal fat biopsies were performed at baseline and month 3.

MAIN OUTCOME MEASURES

Clamp glucose infusion rate, intramyocellular, extramyocellular, and intrahepatic lipid content, 24-hour CPRs, adipocyte size, and adipocyte 11β-hydroxysteroid dehydrogenase activity in adults with GH deficiency were evaluated.

RESULTS

At month 1, LGH did not alter fasting levels of glucose, insulin, C-peptide, free fatty acid, adiponectin, total IGF-1, IGF-1 bioactivity, IGF-2, IGF binding protein (IGFBP)-2, or IGF-1 to IGFBP-3 molar ratio. At month 3, LGH increased clamp glucose infusion rates (P < .01) and IGF-1 to IGFBP-3 molar ratio (P < .05), but fasting glucose, insulin, C-peptide, free fatty acid, adiponectin, IGF-1 bioactivity, IGF-2, IGFBP-2, 24-hour CPRs, adipocyte size, adipocyte 11β-hydroxysteroid dehydrogenase activity, intrahepatic lipid, extramyocellular, or intramyocellular were unchanged. In the placebo group, all within-group parameters from months 1 and 3 compared with baseline were unchanged.

CONCLUSIONS

Short-term LGH therapy improves insulin sensitivity without inducing basal lipolysis and had no effect on cortisol metabolism and ectopic fat accumulation in GH-deficient adults. This may reflect an LGH-induced increase in IGF-1 to IGFBP-3 molar ratio exerting insulin-like effects through the abundant muscle IGF-1 receptors, but this hypothesis requires confirmation with further studies.

Secondary metabolic syndrome: the frequency of factors which may underlie the parameters of metabolic syndrome

BACKGROUND AND OBJECTIVES

Each of the metabolic syndrome (MetS) components (central obesity, hypertriglyceridemia, hypertension, low high-density lipoprotein cholesterol, and insulin resistance) may arise from an underlying disease or factors such as hormonal or pharmacological factors. These components arising secondary to a reason other than life style disturbances cause secondary MetS. The present study aimed to present, for the first time, the factors affecting secondary MetS.

DESIGN AND SETTINGS

An observational study at Medeniyet University Goztepe Training and Research Hospital, Istanbul, from June 2010 to February 2011.

PATIENTS AND METHODS

The underlying causes in 902 MetS patients with a mean age of 53.5 (12.9) years, of whom 79% were female, were investigated. A detailed evaluation was made, which comprised a history for drugs, diseases and habits that may manifest MetS parameters, physical examination, and laboratory analysis.

RESULTS

In 10.6% of the patients, hypothyroidism was determined as the main factor affecting secondary MetS, and in 4.1% the use of corticosteroid was determined as the main factor. Other factors underlie affecting secondary MetS are as follows: the use of thiazide diuretics (22.8%), beta-blockers (12.5%), antiphysichotics (2.1%), insulins (12.8%), insulin secretagog oral hypoglycemics (13.8%), thiazolidinediones (4.9%), oral contraceptives (0.8%), and alcohol intake (2.2%).

CONCLUSION

Hypothyroidism and corticosteroid treatment are the leading causes of secondary MetS. While evaluating the patients, it is a prerequisite to determine the high frequency of other factors that may affect the presence and the degree of MetS parameters.

Inhibition of microsomal cortisol production by (-)-epigallocatechin-3-gallate through a redox shift in the endoplasmic reticulum--a potential new target for treating obesity-related diseases

Conversion of cortisone to cortisol by 11β-hydroxysteroid dehydrogenase type 1 (11βHSD1) in the endoplasmic reticulum (ER) of the target cells is a major determinant of glucocorticoid action, and plays an important role in the development of obesity-related diseases. Inhibition of 11βHSD1 activity is, therefore, considered as a promising novel strategy for the treatment of metabolic syndrome and diabetes. Tea flavanols and their major representative, epigallocatechin gallate are known as antiobesity and antidiabetic agents. Their impacts on blood glucose level, hepatic glucose production, and insulin responsiveness resemble those observed on inhibition or depletion of 11βHSD1. We aimed to study the effect of epigallocatechin gallate on 11βHSD1 activity in ER-derived rat liver microsomes by measuring cortisone and cortisol with HPLC. Cortisol production was efficiently suppressed in a concentration dependent manner in intact microsomal vesicles. However, this effect was abolished by membrane permeabilization; and the three proteins involved in the overall process (11βHSD1, hexose 6-phosphate dehydrogenase, and glucose 6-phosphate transporter) were not or only mildly affected. Further investigation revealed the oxidation of luminal NADPH to NADP⁺, which attenuates cortisone reduction and favors cortisol oxidation in this compartment. Such a redox shift in the ER lumen might contribute to the beneficial health effects of tea flavanols and should be regarded as a promising strategy for the development of novel selective 11βHSD1 inhibitors to treat obesity-related diseases.

Effects of 11β-hydroxysteroid dehydrogenase-1 inhibition on hepatic glycogenolysis and gluconeogenesis

The aim of this study was to determine the effect of prolonged 11β-hydroxysteroid dehydrogenase-1 (11β-HSD1) inhibition on basal and hormone-stimulated glucose metabolism in fasted conscious dogs. For 7 days prior to study, either an 11β-HSD1 inhibitor (HSD1-I; n = 6) or placebo (PBO; n = 6) was administered. After the basal period, a 4-h metabolic challenge followed, where glucagon (3×-basal), epinephrine (5×-basal), and insulin (2×-basal) concentrations were increased. Hepatic glucose fluxes did not differ between groups during the basal period. In response to the metabolic challenge, hepatic glucose production was stimulated in PBO, resulting in hyperglycemia such that exogenous glucose was required in HSD-I (P < 0.05) to match the glycemia between groups. Net hepatic glucose output and endogenous glucose production were decreased by 11β-HSD1 inhibition (P < 0.05) due to a reduction in net hepatic glycogenolysis (P < 0.05), with no effect on gluconeogenic flux compared with PBO. In addition, glucose utilization (P < 0.05) and the suppression of lipolysis were increased (P < 0.05) in HSD-I compared with PBO. These data suggest that inhibition of 11β-HSD1 may be of therapeutic value in the treatment of diseases characterized by insulin resistance and excessive hepatic glucose production.

Early childhood growth failure and the developmental origins of adult disease: do enteric infections and malnutrition increase risk for the metabolic syndrome?

Hypotheses regarding the developmental origins of health and disease postulate that developing fetuses - and potentially young children - undergo adaptive epigenetic changes that have longstanding effects on metabolism and other processes. Ongoing research explores whether these adaptations occur during early life following early childhood malnutrition. In the developing world, there remains a high degree of nutritional stunting, defined as linear growth failure caused by inadequate caloric intake, which may be exacerbated by inflammation from ongoing infections. In areas with poor sanitation, children experience vicious cycles of enteric infections and malnutrition, resulting in poor nutrient absorption as a result of changes in the intestinal mucosa, now termed "environmental enteropathy." Emerging evidence links early childhood diarrhea and/or growth failure with an increased occurrence of risk factors for cardiovascular disease in later life, including dyslipidemia, hypertension, and glucose intolerance. The mechanisms for these associations remain poorly understood and may relate to epigenetic responses to poor nutrition, increased inflammation, or both. Given the increased incidence of cardiovascular disease in developing areas of the world, associations between childhood malnutrition, early-life infections, and the increased occurrence of risk factors for cardiovascular disease underscore further reasons to improve nutrition and infection-related outcomes for young children worldwide.

Risk of cardiovascular events in people prescribed glucocorticoids with iatrogenic Cushing's syndrome: cohort study

OBJECTIVE

To investigate whether there is an increased risk of cardiovascular events in people who exhibit iatrogenic Cushing's syndrome during treatment with glucocorticoids.

DESIGN

Cohort study.

SETTING

424 UK general practices contributing to The Health Improvement Network database.

PARTICIPANTS

People prescribed systemic glucocorticoids and with a diagnosis of iatrogenic Cushing's syndrome (n = 547) and two comparison groups: those prescribed glucocorticoids and with no diagnosis of iatrogenic Cushing's syndrome (n = 3231) and those not prescribed systemic glucocorticoids (n = 3282).

MAIN OUTCOME MEASURES

Incidence of cardiovascular events within a year after diagnosis of iatrogenic Cushing's syndrome or after a randomly selected date, and association between iatrogenic Cushing's syndrome and risk of cardiovascular events.

RESULTS

417 cardiovascular events occurred in 341 patients. Taking into account only the first event by patient (coronary heart disease n = 177, heart failure n = 101, ischaemic stroke n = 63), the incidence rates of cardiovascular events per 100 person years at risk were 15.1 (95% confidence interval 11.8 to 18.4) in those prescribed glucocorticoids and with a diagnosis of iatrogenic Cushing's syndrome, 6.4 (5.5 to 7.3) in those prescribed glucocorticoids without a diagnosis of iatrogenic Cushing's syndrome, and 4.1 (3.4 to 4.8) in those not prescribed glucocorticoids. In multivariate analyses adjusted for sex, age, intensity of glucocorticoid use, underlying disease, smoking status, and use of aspirin, diabetes drugs, antihypertensive drugs, lipid lowering drugs, or oral anticoagulant drugs, the relation between iatrogenic Cushing's syndrome and cardiovascular events was strong (adjusted hazard ratios 2.27 (95% confidence interval 1.48 to 3.47) for coronary heart disease, 3.77 (2.41 to 5.90) for heart failure, and 2.23 (0.96 to 5.17) for ischaemic cerebrovascular events). The adjusted hazard ratio for any cardiovascular event was 4.16 (2.98 to 5.82) when the group prescribed glucocorticoids and with iatrogenic Cushing's syndrome was compared with the group not prescribed glucocorticoids.

CONCLUSION

People who use glucocorticoids and exhibit iatrogenic Cushing's syndrome should be aggressively targeted for early screening and management of cardiovascular risk factors.

The Association between Midnight Salivary Cortisol and Metabolic Syndrome in Korean Adults

BACKGROUND

The common characteristics of metabolic syndrome (MetS) and Cushing's syndrome suggest that excess cortisol may be involved in the pathogenesis of MetS. Salivary cortisol measurements are simple and can be surrogates for plasma free cortisol, which is the most biologically active form. We evaluated the association between levels of midnight salivary cortisol and MetS in Korean adults.

METHODS

A total of 46 subjects, aged 20 to 70 years, who visited the Health Care Center at Konkuk University Hospital from August 2008 to August 2009 were enrolled. We compared the levels of midnight salivary cortisol in subjects with MetS with those in subjects without MetS. We analyzed the associations between midnight salivary cortisol levels and components of MetS.

RESULTS

Midnight salivary cortisol levels were higher in the MetS group (70±42.4 ng/dL, n=12) than that in the group without MetS (48.1±36.8 ng/dL, n=34) (P=0.001). Positive correlations were observed between midnight salivary cortisol levels and waist circumference, fasting blood glucose, and homeostasis model assessment of insulin resistance. The risk for MetS was significantly higher in subjects with midnight salivary cortisol levels ≥100 ng/dL than in those with levels <50 ng/dL (odds ratio, 5.9; 95% confidence interval, 2.35 to 36.4).

CONCLUSION

The results showed a positive correlation between midnight salivary cortisol levels and MetS, suggesting that hypercortisolism may be related to MetS.

The impact of maternal overnutrition and obesity on hypothalamic-pituitary-adrenal axis response of offspring to stress

We evaluated the effect of maternal obesity before and throughout gestation on offspring hypothalamic-pituitary-adrenal axis function. Multiparous Rambouillet by Columbia crossbred ewes were fed either 100% of National Research Council (NRC) recommendations (control, C) or 150% of NRC recommendations (obese, OB) from 60 d before mating until lambing. Ten lambs born to OB ewes (five males and five females), and eight lambs born to C ewes (three male and five female) were studied. From delivery to weaning lambs were maintained with their mothers, who were all fed 100% NRC recommendations. After weaning, all lambs were group housed and fed the same diet to meet NRC requirements. At 19 mo of age lambs were placed in individual pens and fed a pelletized diet to meet maintenance requirements. Jugular vein catheters were placed and 2 d later lambs received an intravenous (i.v.) adrenocorticotropic hormone (ACTH) challenge followed by an i.v. corticotropin-releasing hormone (CRH)/arginine vasopressin (AVP) challenge 1 d later. Thirty d later offspring were again catheterized and placed into metabolism crates for 2 d before receiving an isolation stress test. ACTH and cortisol responses to the isolation stress test and CRH/AVP challenge and cortisol responses to ACTH challenge were determined. Cortisol was quantified via radioimmunoassay and ACTH was quantified using an Immulite 1000; both were analyzed using repeated measures using the MIXED procedure of SAS. Offspring from OB ewes had elevated basal plasma ACTH and cortisol compared with C offspring before all three challenges (P < 0.05). Offspring from OB mothers tended (P = 0.06) to have a greater ACTH response after an i.v. CRH/AVP injection than offspring from C mothers (12,340 ± 1,430 vs 8,170 ± 1,570 area under the curve, respectively). Cortisol response to the CRH/AVP and ACTH challenges was not influenced by maternal nutrition (P = 0.46) and averaged 4.77 ± 0.2 μg/dL and 1.94 ± 0.01 μg/dL, respectively. The ACTH response following the isolation stress test was also similar (P = 0.82) for OB and C offspring (147 ± 20 pg/mL), and cortisol response during the isolation stress test was similar between C and OB offspring (P = 0.64, 5.25 ± 0.3 μg/dL). These findings suggest that maternal obesity before and during gestation does not affect stress responses by the offspring, but has an impact on hypothalamic-pituitary-adrenal sensitivity. The lack of differences in cortisol release under the influence of difference concentrations of ACTH during the CRH/AVP challenge could indicate adrenal dysfunction in OB offspring.

Increased urinary glucocorticoid metabolites are associated with metabolic syndrome, hypoadiponectinemia, insulin resistance and β cell dysfunction

Metabolic syndrome (MetS) may have increased cortisol (F) production caused by 11β-hydroxysteroid dehydrogenase 1 (11β-HSD1) in liver and adipose tissue and/or by HPA axis dysregulation. F is then mainly metabolized by liver reductases into inactive tetrahydrometabolites (THMs). We measured THM levels in patients with or without MetS and evaluate the correlation between THMs and anthropometric and biochemical parameters. We recruited 221 subjects, of whom 130 had MetS by ATP III. We evaluated F, cortisone (E), adipokines, glucose, insulin and lipid profiles as well as urinary (24h) F, E and THM levels. β Cell function was estimated by the HOMA Calculator. We observed that patients with MetS showed higher levels of THMs, HOMA-IR and leptin and lower levels of adiponectin and HOMA-β but no differences in F and E in plasma or urine. THM was associated with weight (r = +0.44, p<0.001), waist circumference (r = +0.38, p<0.01), glycemia (r = +0.37, p<0.01), and triglycerides (r = +0.18, p=0.06) and negatively correlated with adiponectin (r = -0.36, p<0.001), HOMA-β (r = -0.21, p<0.001) and HDL (r = -0.29, p<0.01). In a logistic regression model, THM levels were associated with hypertension, hyperglycemia and dyslipidemia. We conclude that MetS is associated with increased urinary THMs but not with F and E levels in plasma or urine. Increased levels of THM, reflecting the daily cortisol production subsequently metabolized, are correlated with hypoadiponectinemia, hypertension, dyslipidemia, insulin resistance and β cell dysfunction. A subtle increased in glucocorticoid production may further account for the phenotypic and biochemical similarities observed in central obesity and Cushing's syndrome.