11 beta-Hydroxysteroid dehydrogenase activity in hypothalamic obesity

Cortisol, cortisone and DHEAS in epidermis and scales of fish Aphanius fasciatus: HPLC-MS/MS measurement of stress indicators as proxies for natural and human-induced factors

Fish health can be affected by a multitude of stressors. Acute and chronic stress assessment via specific hormones monitoring has become a trending research topic. Common investigated matrices are blood and plasma, but recently less invasive substrates have been identified. As chemical composition of skin mucus/epidermis has been demonstrated to link with acute stress, and of scales with chronic stress in fish, the aim of the study was firstly to improve the determination of three stress hormones, namely cortisol (COL), cortisone (CON), and dehydroepiandrosterone-3-sulfate (DHEAS), in skin mucus/epidermis and scales of Aphanius fasciatus. Secondly, an evaluation of the impact of different environments on hormones concentrations was carried out. A liquid chromatography coupled to tandem mass spectrometry method (HPLC-MS/MS) and a preanalytical procedure were validated to determine COL, CON and DHEAS. This methodology was applied to compare a pull of field-collected fish with a pull of fish housed in the laboratory for one year. Our results highlighted a significant presence of cortisol and cortisone in epidermis of the latter pull (averagely 0.10 and 0.14 ng mg-1, respectively), while in the first pull both hormones were much less concentrated (averagely 0.006 and 0.008 ng mg-1, respectively). Scales of both pulls showed presence of hormones, with a higher concentration for fish housed in the laboratory, although a relevant difference in concentration was found only for cortisone. DHEAS was always below the limit of detection.

Craniopharyngioma-An update on metabolic and cognitive complications and new therapy

Craniopharyngiomas (CPs) are rare primary brain epithelial tumors arising in the suprasellar region from remnants of Rathke's pouch. About 50% originate at the level of the third ventricle floor, including the hypothalamus (HT). CPs are characterized by a low proliferation rate and symptoms due to mass effect and local infiltration and are managed primarily with surgery and radiotherapy. Gross total removal of a CP will reduce the recurrence rate but increases the risk of HT damage. Today, subtotal resection is the goal and will reduce the risk of HT damage. There are two histological subtypes of CP-adamantinomatous (ACP) and papillary CP (PCP)-that differ in their genesis and age distribution. ACPs are driven by somatic mutations in CTNNB1 gene (encoding β-catenin), and PCPs frequently harbor somatic BRAF V600E mutations. There are also two phenotypes of outcome, the one with a rather good outcome without HT damage and the other with HT damage where recurrent operation with additional cranial radiotherapy results in HT obesity (HO), affecting psychosocial life and cognitive dysfunction. The group with HO suffers from metabolic syndrome, lower basal metabolic rate, and leptin and insulin resistances. There is currently no successful treatment for HO. The group with HT damage suffers from cognitive dysfunction with attention deficits, impaired episodic memory, and processing speed. Diffusion tensor imaging has shown significant microstructural white matter alteration in several areas important for cognition. Recently, complete or partial tumor response was shown to targeted therapy, with BRAF and Mekinist inhibitors for PCPs with BRAF V600E mutation.

Serum and hair steroid profiles in patients with nonfunctioning pituitary adenoma undergoing surgery: A prospective observational study

Patients who undergo transsphenoidal surgery (TSS) experience perioperative hormonal changes, but there are few studies on the perioperative changes of serum and hair steroid profiles. This study investigated the perioperative changes in steroid metabolic signatures in patients with nonfunctioning pituitary adenoma (NFPA) who underwent transsphenoidal surgery (TSS). A total of 55 participants who underwent TSS for NFPA at a single center between July 2017 and October 2018 were enrolled. Fifteen serum steroids and their metabolic ratios were profiled using gas chromatography-mass spectrometry (GC-MS) before and 1 day, 1 week, and 3 months after TSS. Five steroids from hair samples collected 1 day and 3 months after TSS were also quantitatively compared. Serum cortisol and its A-ring reductive metabolites, as well as 6β-hydroxycortisol, increased dramatically 1 day after TSS and then gradually decreased. Seven serum steroids, including adrenal androgens and mineralocorticoids, and hair cortisone levels were significantly lower in patients with preoperative adrenocorticotropic hormone (ACTH) deficiency (N = 7) than in those without ACTH deficiency (N = 48). Serum levels of dehydroepiandrosterone (DHEA) levels 1 week after TSS predicted ACTH deficiency 3 months after TSS, with 100 % sensitivity and 86 % specificity. A significant positive correlation between the preoperative serum and hair DHEA levels (r = 0.356, P = 0.008) was observed. These findings suggest that the levels of DHEA in both the serum and hair could be an early marker of ACTH deficiency after TSS. In addition, hair cortisone may be a useful preoperative indicator of chronic ACTH deficiency.

Hypothalamic syndrome

Hypothalamic syndrome (HS) is a rare disorder caused by disease-related and/or treatment-related injury to the hypothalamus, most commonly associated with rare, non-cancerous parasellar masses, such as craniopharyngiomas, germ cell tumours, gliomas, cysts of Rathke's pouch and Langerhans cell histiocytosis, as well as with genetic neurodevelopmental syndromes, such as Prader-Willi syndrome and septo-optic dysplasia. HS is characterized by intractable weight gain associated with severe morbid obesity, multiple endocrine abnormalities and memory impairment, attention deficit and reduced impulse control as well as increased risk of cardiovascular and metabolic disorders. Currently, there is no cure for this condition but treatments for general obesity are often used in patients with HS, including surgery, medication and counselling. However, these are mostly ineffective and no medications that are specifically approved for the treatment of HS are available. Specific challenges in HS are because the syndrome represents an adverse effect of different diseases, and that diagnostic criteria, aetiology, pathogenesis and management of HS are not completely defined.

The Potential Role of Exosomes in Child and Adolescent Obesity

Child and adolescent obesity constitute one of the greatest contemporary public health menaces. The enduring disproportion between calorie intake and energy consumption, determined by a complex interaction of genetic, epigenetic, and environmental factors, finally leads to the development of overweight and obesity. Child and adolescent overweight/obesity promotes smoldering systemic inflammation (“para-inflammation”) and increases the likelihood of later metabolic and cardiovascular complications, including metabolic syndrome and its components, which progressively deteriorate during adulthood. Exosomes are endosome-derived extracellular vesicles that are secreted by a variety of cells, are naturally taken-up by target cells, and may be involved in many physiological and pathological processes. Over the last decade, intensive research has been conducted regarding the special role of exosomes and the non-coding (nc) RNAs they contain (primarily micro (mi) RNAs, long (l) non-coding RNAs, messenger (m) RNAs and other molecules) in inter-cellular communications. Through their action as communication mediators, exosomes may contribute to the pathogenesis of obesity and associated disorders. There is increasing evidence that exosomal miRNAs and lncRNAs are involved in pivotal processes of adipocyte biology and that, possibly, play important roles in gene regulation linked to human obesity. This review aims to improve our understanding of the roles of exosomes and their cargo in the development of obesity and related metabolic and inflammatory disorders. We examined their potential roles in adipose tissue physiology and reviewed the scarce data regarding the altered patterns of circulating miRNAs and lncRNAs observed in obese children and adolescents, compared them to the equivalent, more abundant existing findings of adult studies, and speculated on their proposed mechanisms of action. Exosomal miRNAs and lncRNAs could be applied as cardiometabolic risk biomarkers, useful in the early diagnosis and prevention of obesity. Furthermore, the targeting of crucial circulating exosomal cargo to tissues involved in the pathogenesis and maintenance of obesity could provide a novel therapeutic approach to this devastating and management-resistant pandemic.

Steroid metabolomic signature of liver disease in nonsyndromic childhood obesity

OBJECTIVE

Analysis of steroids by gas chromatography-mass spectrometry (GC-MS) defines a subject's steroidal fingerprint. Here, we compare the steroidal fingerprints of obese children with or without liver disease to identify the 'steroid metabolomic signature' of childhood nonalcoholic fatty liver disease.

METHODS

Urinary samples of 85 children aged 8.5-18.0 years with BMI >97% were quantified for 31 steroid metabolites by GC-MS. The fingerprints of 21 children with liver disease (L1) as assessed by sonographic steatosis (L1L), elevated alanine aminotransferases (L1A) or both (L1AL), were compared to 64 children without markers of liver disease (L0). The steroidal signature of the liver disease was generated as the difference in profiles of L1 against L0 groups.

RESULTS

L1 comparing to L0 presented higher fasting triglycerides (P = 0.004), insulin (P = 0.002), INS/GLU (P = 0.003), HOMA-IR (P = 0.002), GGTP (P = 0.006), AST/SGOT (P = 0.002), postprandial glucose (P = 0.001) and insulin (P = 0.011). L1AL showed highest level of T-cholesterol and triglycerides (P = 0.029; P = 0.044). Fasting insulin, postprandial glucose, INS/GLU and HOMA-IR were highest in L1L and L1AL (P = 0.001; P = 0.017; P = 0.001; P = 0.001). The liver disease steroidal signature was marked by lower DHEA and its metabolites, higher glucocorticoids (mostly tetrahydrocortisone) and lower mineralocorticoid metabolites than L0. L1 patients showed higher 5α-reductase and 21-hydroxylase activity (the highest in L1A and L1AL) and lower activity of 11βHSD1 than L0 (P = 0.041, P = 0.009, P = 0.019).

CONCLUSIONS

The 'steroid metabolomic signature' of liver disease in childhood obesity provides a new approach to the diagnosis and further understanding of its metabolic consequences. It reflects the derangements of steroid metabolism in NAFLD that includes enhanced glucocorticoids and deranged androgens and mineralocorticoids.

Management of hypothalamic disease in patients with craniopharyngioma

Patients with craniopharyngioma experience excess morbidity and mortality when compared with the background population and with other hypopituitary patients. Large, suprasellar tumours which form micropapillae into surrounding structures can cause hypothalamic damage before any therapeutic intervention; attempted gross total resection can lead to hypothalamic obesity, sleep disorders, thirst disorders and dysregulation of temperature as well as panhypopituitarism. The management of tumour bulk and the pathophysiology of hypothalamic complications have been reviewed extensively. We present a practical, clinical approach to management of hypothalamic disease in a patient with craniopharyngioma and highlight potential targets for future pharmacological or surgical intervention.

Pathophysiology and Individualized Treatment of Hypothalamic Obesity Following Craniopharyngioma and Other Suprasellar Tumors: A Systematic Review

The development of hypothalamic obesity (HO) following craniopharyngioma (CP) and other suprasellar tumors leads to reduced patient quality of life. No treatment algorithms are currently available for management of HO. Depending on which hypothalamic nuclei are destroyed, the pathophysiologic mechanisms and clinical symptoms that contribute to HO differ among patients. Herein, we review the contribution of the hypothalamus to the pathophysiologic mechanisms and symptoms underlying CP-associated HO. Additionally, we performed a systematic search of MEDLINE and Embase to identify all intervention studies for weight management in patients with CP or other suprasellar tumors published until September 2017. The search yielded 1866 publications, of which 40 were included. Of these 40 studies, we identified four modalities for intervention (i.e., lifestyle, dietary, pharmacotherapeutic, or surgical) within six clinical domains (i.e., psychosocial disorders, hyperphagia, sleep disturbances, decreased energy expenditure, hyperinsulinemia, and hypopituitarism). We used the findings from our systematic review, in addition to current knowledge on the pathophysiology of HO, to develop an evidence-based treatment algorithm for patients with HO caused by CP or other suprasellar tumors. Although the individual effects of the HO interventions were modest, beneficial individual effects may be achieved when the pathophysiologic background and correct clinical domain are considered. These two aspects can be combined in an individualized treatment algorithm with a stepwise approach for each clinical domain. Recently elucidated targets for HO intervention were also explored to improve future management of HO for patients with CP and other suprasellar tumors.

The cortisol-activating enzyme 11β-hydroxysteroid dehydrogenase type 1 in skeletal muscle in the pathogenesis of the metabolic syndrome

The enzyme 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1) contributes to intracellular glucocorticoid action by converting inactive cortisone to its receptor-active form cortisol (11-dehydrocorticosterone and corticosterone in mice and rats). The potential role of 11β-HSD1 in the pathogenesis of the metabolic syndrome has emerged over the past three decades. However, the precise impact of 11β-HSD1 in obesity-related diseases remains uncertain. Many studies from animal experiments to clinical studies have investigated liver and adipose tissue 11β-HSD1 in relation to obesity and its metabolic disorders including insulin resistance. But the relevance of 11β-HSD1 in skeletal muscle has been less extensively studied. On the other hand, skeletal muscle is assumed to be the main site of peripheral insulin resistance, but the biological relevance of 11β-HSD1 in skeletal muscle is unclear. This mini-review will focus on 11β-HSD1 in skeletal muscle and its postulated link to obesity and insulin-resistance.

Steroid Metabolomic Disease Signature of Nonsyndromic Childhood Obesity

CONTEXT

The profile of urinary steroids as measured by gas chromatography-mass spectrometry defines a subject's "steroidal fingerprint."

OBJECTIVE

Here, we clustered steroidal fingerprints to characterize patients with nonsyndromic childhood obesity by "steroid metabolomic signatures."

HYPOTHESIS

Nonsyndromic obesity is a symptom of different diseases and conditions, some of them will have their own signature.

DESIGN

A total of 31 steroid metabolites were quantified by gas chromatography-mass spectrometry, and their excretion rates were z-transformed. Using MetaboAnalyst 3.0, we divided the subjects into 5 distinctive groups by k-means clustering. Steroidal fingerprints and clinical/biochemical data of patients in each cluster were analyzed.

PATIENTS

A total of 87 obese children (44 females), aged 8.5-17.9 years, were clinically characterized, and their 24-hour urine was collected.

RESULTS

Cluster 1 (n = 39, 21 females) had normal steroid profile. Cluster 2 (n = 20, 11 females) showed mild, nonspecific elevation of C19 and C21 steroids, females' resistance to polycystic ovary morphology, and hirsutism. Cluster 3 (n = 7 female), with relative 21-hydroxylase insufficiency, was characterized by partial or full polycystic ovary syndrome. Cluster 4 (n = 4 males), showed markedly elevated C21 steroids and imbalance in the 11β-hydroxysteroid dehydrogenase system, higher insulin, increased frequency of glucose/insulin index more than 0.3, γ-glutamyl transpeptidase activity, systolic blood pressure, and tendency to liver steatosis. Cluster 5 (n = 17, 5 females) had elevated dehydroepiandrosterone and 17-OH-pregnenolone metabolites, suggesting 3β-hydroxysteroid dehydrogenase insufficiency but no clinically unique phenotype. Z-score body mass index values were not significantly different between the clusters.

CONCLUSIONS

We defined a novel concept of disease-specific steroid metabolomic signature based on urinary steroidal gas chromatography-mass spectrometry. Clustering by software designed for metabolic data analysis reclassified childhood obesity into 5 groups with distinctive signatures; groups require further definition and may require cluster-specific therapeutic strategies.

Management of Craniopharyngioma - Perspectives beyond Surgery and Endocrinology

The excess mortality in craniopharyngiomas is attributable to their size, site and the traditional surgical approach; aggressive resection predisposes to hypothalamic complications such as obesity, somnolence, thirst disorders and neurocognitive dysfunction. Recently, treatment has been modified to partial resection and radiotherapy. The role of the endocrinologist has expanded from identification and replacement of hormone deficits to include management of hypothalamic disease. Future treatment of craniopharyngioma with neo-adjuvant chemotherapy to minimise surgical resection may improve the outcomes for these patients.

Hypothalamic obesity in children: pathophysiology to clinical management

Hypothalamic obesity (HyOb) is a complex neuroendocrine disorder caused by damage to the hypothalamus, which results in disruption of energy regulation. The key hypothalamic areas of energy regulation are the ARC (arcuate nucleus), the VMH (ventromedial hypothalamus), the PVN (paraventriculer nuclei) and the LHA (lateral hypothalamic area). These pathways can be disrupted mechanically by hypothalamic tumors, neurosurgery, inflammatory disorders, radiotherapy and trauma or functionally as such seen in genetic diseases. Rapid weight gain and severe obesity are the most striking features of HyOb and caused by hyperphagia, reduced basal metabolic rate (BMR) and decreased physical activity. HyOb is usually unresponsive to diet and exercise. Although, GLP-1 and its anologs seem to be a new agent, there is still no curative treatment. Thus, prevention is of prime importance and the clinicians should be alert and vigilant in patients at risk for development of HyOb.

Pathophysiology and clinical characteristics of hypothalamic obesity in children and adolescents

The hypothalamus plays a key role in the regulation of body weight by balancing the intake of food, energy expenditure, and body fat stores, as evidenced by the fact that most monogenic syndromes of morbid obesity result from mutations in genes expressed in the hypothalamus. Hypothalamic obesity is a result of impairment in the hypothalamic regulatory centers of body weight and energy expenditure, and is caused by structural damage to the hypothalamus, radiotherapy, Prader-Willi syndrome, and mutations in the LEP, LEPR, POMC, MC4R and CART genes. The pathophysiology includes loss of sensitivity to afferent peripheral humoral signals, such as leptin, dysregulated insulin secretion, and impaired activity of the sympathetic nervous system. Dysregulation of 11β-hydroxysteroid dehydrogenase 1 activity and melatonin may also have a role in the development of hypothalamic obesity. Intervention of this complex entity requires simultaneous targeting of several mechanisms that are deranged in patients with hypothalamic obesity. Despite a great deal of theoretical understanding, effective treatment for hypothalamic obesity has not yet been developed. Therefore, understanding the mechanisms that control food intake and energy homeostasis and pathophysiology of hypothalamic obesity can be the cornerstone of the development of new treatments options. Early identification of patients at-risk can relieve the severity of weight gain by the provision of dietary and behavioral modification, and antiobesity medication. This review summarizes recent advances of the pathophysiology, endocrine characteristics, and treatment strategies of hypothalamic obesity.

Hypothalamic obesity in children

Hypothalamic obesity is an intractable form of obesity syndrome that was initially described in patients with hypothalamic tumours and surgical damage. However, this definition is now expanded to include obesity developing after a variety of insults, including intracranial infections, infiltrations, trauma, vascular problems and hydrocephalus, in addition to acquired or congenital functional defects in central energy homeostasis in children with the so-called common obesity. The pathogenetic mechanisms underlying hypothalamic obesity are complex and multifactorial. Weight gain results from damage to the ventromedial hypothalamus, which leads, variously, to hyperphagia, a low-resting metabolic rate; autonomic imbalance; growth hormone-, gonadotropins and thyroid-stimulating hormone deficiency; hypomobility; and insomnia. Hypothalamic obesity did not receive enough attention, as evidenced by rarity of studies in this group of patients. A satellite symposium was held during the European Congress of Obesity in May 2011, in Istanbul, Turkey, to discuss recent developments and concepts regarding pathophysiology and management of hypothalamic obesity in children. An international group of leading researchers presented certain aspects of the problem. This paper summarizes the highlights of this symposium. Understanding the central role of the hypothalamus in the regulation of feeding and energy metabolism will help us gain insights into the pathogenesis and management of common obesity.

G6PT-H6PDH-11βHSD1 triad in the liver and its implication in the pathomechanism of the metabolic syndrome

The metabolic syndrome, one of the most common clinical conditions in recent times, represents a combination of cardiometabolic risk determinants, including central obesity, glucose intolerance, insulin resistance, dyslipidemia, non-alcoholic fatty liver disease and hypertension. Prevalence of the metabolic syndrome is rapidly increasing worldwide as a consequence of common overnutrition and consequent obesity. Although a unifying picture of the pathomechanism is still missing, the key role of the pre-receptor glucocorticoid activation has emerged recently. Local glucocorticoid activation is catalyzed by a triad composed of glucose-6-phosphate-transporter, hexose-6-phosphate dehydrogenase and 11β-hydroxysteroid dehydrogenase type 1 in the endoplasmic reticulum. The elements of this system can be found in various cell types, including adipocytes and hepatocytes. While the contribution of glucocorticoid activation in adipose tissue to the pathomechanism of the metabolic syndrome has been well established, the relative importance of the hepatic process is less understood. This review summarizes the available data on the role of the hepatic triad and its role in the metabolic syndrome, by confronting experimental findings with clinical observations.

Biomedical evaluation of cortisol, cortisone, and corticosterone along with testosterone and epitestosterone applying micellar electrokinetic chromatography

The validated micellar electrokinetic chromatography (MEKC) was proposed for the determination of five steroid hormones in human urine samples. That technique allowed for the separation and quantification of cortisol, cortisone, corticosterone, testosterone, and epitestosterone and was sensitive enough to detect low concentrations of these searched steroids in urine samples at the range of 2–300 ng/mL. The proposed MEKC technique with solid-phase extraction (SPE) procedure was simple, rapid, and has been successfully applied as a routine procedure to analyze steroids in human urine samples. The MEKC method offered a potential in clinical routine practice because of the short analysis time (8 min), low costs, and simultaneous analysis of five endogenous hormones. Due to its simplicity, speed, accuracy, and high recovery, the proposed method could offer a tool to determine steroid hormones as potential biomarkers in biomedical investigations, what was additionally revealed with healthy volunteers.

Hypothalamic obesity in patients with craniopharyngioma: treatment approaches and the emerging role of gastric bypass surgery

Hypothalamic obesity is a potential sequela of craniopharyngioma, arising from hypothalamic damage inflicted by either the tumor and/or its treatment. The marked weight gain that characterizes this disorder appears to result from impaired sympathoadrenal activation, parasympathetic dysregulation, and other hormonal and hypothalamic disturbances that upset the balance between energy intake and expenditure. Given hypopituitarism is commonly present, careful management of hormonal deficits is important for weight control in these patients. In addition, diet, exercise, and pharmacotherapy aimed at augmenting sympathetic output, controlling hyperinsulinism, and promoting weight loss have been used to treat this disease, but these measures rarely lead to sustained weight loss. While surgical interventions have not routinely been pursued, emerging data suggests that surgical weight loss interventions including Roux-en-Y gastric bypass can be safely and effectively used for the management of hypothalamic obesity in patients with craniopharyngioma.

Hypothalamic obesity after craniopharyngioma: mechanisms, diagnosis, and treatment

Obesity is a common complication after craniopharyngioma therapy, occurring in up to 75% of survivors. Its weight gain is unlike that of normal obesity, in that it occurs even with caloric restriction, and attempts at lifestyle modification are useless to prevent or treat the obesity. The pathogenesis of this condition involves the inability to transduce afferent hormonal signals of adiposity, in effect mimicking a state of CNS starvation. Efferent sympathetic activity drops, resulting in malaise and reduced energy expenditure, and vagal activity increases, resulting in increased insulin secretion and adipogenesis. Lifestyle intervention is essentially useless in this syndrome, termed "hypothalamic obesity." Pharmacologic treatment is also difficult, consisting of adrenergics to mimic sympathetic activity, or suppression of insulin secretion with octreotide, or both. Recently, bariatric surgery (Roux-en-Y gastric bypass, laparoscopic gastric banding, truncal vagotomy) have also been attempted with variable results. Early and intensive management is required to mitigate the obesity and its negative consequences.

11β-Hydroxysteroid dehydrogenase type 1 activity in short small-for-GA children and in response to GH therapy

Small for GA (SGA) children are at risk for developing the metabolic syndrome. Those who do not catch up, and remain short (SSGA), may benefit from GH therapy. 11β Hydroxysteroid dehydrogenase type 1 (11β-HSD-1) is expressed in visceral fat and is implicated in metabolic morbidity. We hypothesized that SSGA children will have increased basal and glucocorticoid (GC)-stimulated 11β-HSD-1 activity. Twenty SSGA children, aged 7.1 ± 1 y (mean ± SD), were studied before and while on GH therapy and compared with 12 normal age-matched controls. 11β-HSD-1 activity was evaluated by gas chromatography mass spectrometry (GCMS) of urinary steroid product/substrate ratios. GC-stimulated 11β-HSD-1 activity was assessed after overnight dexamethazone (DEX), by oral cortisone conversion to cortisol. In SSGA children, 11β-HSD-1 activity was lower (p < 0.05) and GC-stimulated activity enhanced. SSGA children had maximal cortisol generation of 883 ± 108 compared with 690 ± 63 nmol/L in controls (p < 0.04). GH treatment suppressed 11β-HSD-1 activity. GC-stimulated enzyme activity correlated negatively with GA (r = -0.53, p < 0.01) and birth weight (r = -0.55, p < 0.01). SSGA is associated with enhanced GC-stimulated 11β-HSD-1 activity. This may be programmed in utero, as it is not a function of body composition or secondary metabolic derangement. GH therapy normalizes GC-stimulated 11β-HSD-1 activity.

Tissue-specific dysregulation of hexose-6-phosphate dehydrogenase and glucose-6-phosphate transporter production in db/db mice as a model of type 2 diabetes

AIMS/HYPOTHESIS

Tissue-specific amplification of glucocorticoid action through 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1) affects the development of the metabolic syndrome. Hexose-6-phosphate dehydrogenase (H6PDH) mediates intracellular NADPH availability for 11β-HSD1 and depends on the glucose-6-phosphate transporter (G6PT). Little is known about the tissue-specific alterations of H6PDH and G6PT and their contributions to local glucocorticoid action in db/db mice.

METHODS

We characterised the role of H6PDH and G6PT in pre-receptor metabolism of glucocorticoids by examining the production of the hepatic 11β-HSD1-H6PDH-G6PT system in db/db mice.

RESULTS

We observed that increased production of hepatic H6PDH in db/db mice was paralleled by upregulation of hepatic G6PT production and responded to elevated circulating levels of corticosterone. Treatment of db/db mice with the glucocorticoid antagonist RU486 markedly reduced production of both H6PDH and 11β-HSD1 and improved hyperglycaemia and insulin resistance. The reduction of H6PDH and 11β-HSD1 production by RU486 was accompanied by RU486-induced suppression of hepatic G6pt (also known as Slc37a4) mRNA. Incubation of mouse primary hepatocytes with corticosterone enhanced G6PT and H6PDH production with corresponding activation of 11β-HSD1 and PEPCK: effects that were blocked by RU486. Knockdown of H6pd by small interfering RNA showed effects comparable with those of RU486 for attenuating the corticosterone-induced H6PDH production and 11ß-HSD1 reductase activity in these intact cells. Addition of the G6PT inhibitor chlorogenic acid to primary hepatocytes suppressed H6PDH production.

CONCLUSIONS/INTERPRETATION

These findings suggest that increased hepatic H6PDH and G6PT production contribute to 11β-HSD1 upregulation of local glucocorticoid action that may be related to the development of type 2 diabetes.

Signal transduction in child health: closing the gap between clinical and basic research

Although some diseases are specific to children, many diseases of adults, including obesity and the metabolic syndrome, often originate in childhood. Thus, understanding the mechanisms of disease onset and progression in children is vital not only for child health, but for adult health as well. The NICHe (New Inroads to Child Health) Conference series focuses on future directions in child health, by bringing together clinical and basic scientists with the aim of sharing knowledge to facilitate the development of new therapeutic approaches. This year's conference, entitled "Child Health and Signal Transduction," focused on G protein-coupled receptor and receptor tyrosine kinase pathways involved in endocrine signaling, how disruption of these pathways can lead to disease, and how understanding these pathways may guide drug discovery.

Expanding the definition of hypothalamic obesity

Hypothalamic obesity (HyOb) was first defined as the significant polyphagia and weight gain that occurs after extensive suprasellar operations for excision of hypothalamic tumours. However, polyphagia and weight gain complicate other disorders related to the hypothalamus, including those that cause structural damage to the hypothalamus like tumours, trauma, radiotherapy; genetic disorders such as Prader-Willi syndrome; side effects of psychotropic drugs; and mutations in several genes involved in hypothalamic satiety signalling. Moreover, 'simple' obesity is associated with polymorphisms in several genes involved in hypothalamic weight-regulating pathways. Thus, understanding HyOb may enhance our understanding of 'simple' obesity. This review will claim that HyOb is a far wider phenomenon than hitherto understood by the narrow definition of post-surgical weight gain. It will emphasize the similarity in clinical characteristics and therapeutic approaches for HyOb, as well as its mechanisms. HyOb, regardless of its aetiology, is a result of impairment in hypothalamic regulatory centres of body weight and energy expenditure. The pathophysiology includes loss of sensitivity to afferent peripheral humoral signals, such as, leptin on the one hand and dysfunctional afferent signals, on the other hand. The most important afferent signals deranged are energy regulation by the sympathetic nervous system and regulation of insulin secretion. Dys-regulation of 11β-hydroxysteroid dehydrogenase 1 (11β-HSD1) activity and melatonin may also have a role in the development of HyOb. The complexity of the syndrome requires simultaneous targeting of several mechanisms that are deranged in the HyOb patient. We review the studies evaluating possible treatment strategies, including sympathomimetics, somatostatin analogues, triiodothyronine, sibutramine, and surgery.

Abnormal urinary steroid profiles in four hypertensive obese children

BACKGROUND

There is a poorly understood association between obesity and hypertension. We demonstrated abnormalities of adrenal androgen and cortisol metabolites in four hypertensive obese children.

PATIENTS

Four males (aged 10 to 15 years) were evaluated for systolic blood pressures consistently above the 99.6th percentile. All were overweight with BMI ranging from 27-35. Clinical examinations, renal ultrasound and DMSA scans were normal. Plasma electrolytes, renin, aldosterone, cortisol, testosterone, ACTH and TSH were normal. 24-Hour urinary steroid profiles showed a generalised excess of adrenal androgen and cortisol metabolites in all cases. Relevant recognised disorders of adrenal androgen and cortisol metabolism were excluded.

CONCLUSION

There is no clinical condition explaining these abnormal urinary steroid profiles. These results support previous findings and provide new data on abnormal urinary adrenal androgen excretion in obese hypertensive patients. Further studies may determine the relationship between obesity, hypertension and the observed abnormalities of urinary steroid excretion.

Androgen replacement therapy in Turner syndrome: a pilot study

CONTEXT

Women with Turner syndrome (TS) have reduced levels of androgens due to ovarian failure.

HYPOTHESES

Morbidity associated with TS, such as bone fragility, metabolic changes, obesity, neurocognitive profile, and sexual problems may partly relate to androgen insufficiency and improve on androgen replacement therapy (ART).

OBJECTIVES

The objective of the study was to determine the effect of androgens on morbidity in TS.

DESIGN

Fourteen TS women (aged 17-27 yr) participated in a randomized, double-blind, placebo-controlled crossover pilot. The study was conducted in a hospital outpatient clinic between December 2001 and July 2004.

INTERVENTION

TS patients were on estrogen/progestin replacement therapy. Subjects received oral 1.5 mg methyl testosterone (ART) or placebo for 1 yr and the alternative for another year.

MAIN OUTCOME MEASURES

The study compared body composition as a primary outcome, and physiology, biochemistry, visceral fat, cognition, and quality of life (QOL) as secondary outcomes.

RESULTS

ART as compared with placebo reduced total cholesterol, triglycerides, and high-density lipoprotein cholesterol. It improved bone mineral density, increased lean body mass, and decreased fat mass. ART improved attention, reaction time, and verbal memory and had no effect on executive functions and spatial cognition. Patients reported improved QOL, including general health, coping with stress, and sexual desire.

CONCLUSIONS

Androgen insufficiency plays a role in TS-impaired body composition, neurocognition, and QOL, and these aspects improve with ART, which was safe and effective when given for 1 yr.

HPLC method for determination of fluorescence derivatives of cortisol, cortisone and their tetrahydro- and allo-tetrahydro-metabolites in biological fluids

11Beta-hydroxysteroid dehydrogenase isoform 2 (11beta-HSD2) is responsible for conversion of cortisol (F) to inactive cortisone (E). Disturbance of its activity can cause hypertension. To estimate 11beta-HSD2 activity, besides F and E, their tetrahydro- (THF, THE) as well allo-tetrahydro- (allo-THF, allo-THE) metabolites should be determined. This study describes HPLC-FLD method for the quantitative determination of endogenous glucocorticoids (GCs) in plasma and urine (total and free) and their metabolites in urine. Following extraction at pH 7.4 using dichloromethane, GCs (F, E, THF, allo-THF, THE, allo-THE and internal standard--prednisolone) were derivatized with 9-anthroyl nitrile and purified by SPE using C(18) cartridges. The enzymatic hydrolysis of conjugated steroids was provided using beta-glucuronidase. The influence of organic bases on 9-AN derivatization of steroids was investigated. The best yield of the derivatization was obtained in presence of the mixture of 10.0% triethylamine (TEA) and 0.1% quinuclidine (Q). Chromatographic separation was accomplished in the Chromolith RP-18e monolithic column. The elaborated method was validated. Calibration curves were linear in the ranges: for F, E and THF 5.0-1000.0 ng mL(-1), for allo-THF and THE + allo-THE 10.0-1000.0 ng mL(-1). LOD (S/N=3:1) for all analytes amounted 3.0 ng mL(-1). Recoveries of GCs exceeded 90%. The method was precise and accurate, intra- and inter-day precision were 3.0-12.1% and 9.2-14.0%, respectively. Accuracy ranged from 0.2 to 15.1%. The method was applied for estimating endogenous GCs in plasma and urine. Plasma levels of F and E were in the ranges: 133.0-174.5 ng mL(-1) and 17.4-35.9 ng mL(-1), respectively. Free urinary steroids were in the ranges: 12.0-54.1 microg/24 h (UFF) and 37.8-76.2 microg/24 h (UFE). The ratio of (THF + allo-THF)/(THE + allo-THE) amounted from 1.01 to 1.23. The obtained results confirmed utility of the elaborated method in the assessment of 11beta-HSD2 activity in man.

The role of leptin, soluble leptin receptor, resistin, and insulin secretory dynamics in the pathogenesis of hypothalamic obesity in children

INTRODUCTION

In this study, we have investigated the role of leptin, soluble leptin receptor(sOb-R), resistin, and insulin secretory dynamics in the development of hypothalamic obesity.

MATERIALS AND METHODS

Children who had hypothalamo-pituitary tumor were divided into two groups. First group included obese-overweight (hypothalamic obese = HOB group, n = 23) and second group included non-obese children (hypothalamic non-obese = HNOB group, n = 16). Exogenously obese-overweight children (OB group, n = 22) were included as controls. Basal and second-hour serum glucose and insulin in oral glucose tolerance test (OGTT), basal serum leptin, sOb-R, resistin levels, and homeostasis model assessment (HOMA) indexes were compared between the groups.

RESULTS

Age, sex, and pubertal status were similar in study groups. Median and interquartile ranges of body mass index (BMI) z scores were similar in HOB and OB groups (2.0 (1.5-2.1) and 2.1 (1.8-2.3), respectively). Serum leptin levels corrected for BMI were highest and total leptin/sOb-R ratios (free leptin index (FLI)) tended to be higher in HOB than HNOB and OB groups, indicating leptin resistance (leptin/BMI, 4.0 (1.6-5.2), 1.5 (0.8-3.1), and 2.5 (1.8-3.5); FLI, 2.0 (0.8-3.5), 0.6 (0.3-1.2), and 1.5 (1-2.3) in HOB, HNOB, and OB groups; respectively). Serum resistin levels were similar in groups (2.6 (1.9-3.1), 2.8 (1.7-3.4), and 3.0 (2.2-3.5) ng/ml in HOB, HNOB, and OB groups, respectively). Basal serum glucose, basal and second-hour insulin levels in OGTT, and HOMA index were higher in OB group than the HOB and HNOB groups, indicating insulin resistance in simple obesity; however, increment of insulin to same glycemic load in OGTT was highest in the HOB group indicating insulin dysregulation (p < 0.05).

CONCLUSION

Hypothalamic obesity seems to be related to both dysregulated afferent (leptin) and efferent (insulin) neural outputs through the autonomic nervous system resulting in energy storage as fat.

Recent advances in the assessment of the ratios of cortisol to cortisone and of some of their metabolites in urine by LC-MS-MS

A previously reported method for the assessment of the ratio of tetrahydrocortisol (THF) + allo-tetrahydrocortisol (A-THF) to tetrahydrocortisone (THE) by HPLC-MS-MS has been significantly improved, in order to increase either ruggedness and reliability. That was achieved by the introduction of an on-line sample cleanup stage, which made use of a perfusion column as a solid phase microextraction (SPE) cartridge. The set of analytes was expanded, by introducing cortisol and cortisone, whose ratio supply additional diagnostic information. The response factors of both THF and A-THF has been checked, resulting almost identical, as well as the influence of the matrix on the calibration curves which, although different for water and urine, had similar effect on the ratios of interest. As a consequence, the calibration solutions can be prepared in pure water. The influence of several different storage procedures has also been tested, resulting in no substantial effect on the final result. Finally, the improved method has been used to run real samples from healthy volunteers, with satisfactory results.

Review of physiology, clinical manifestations, and management of hypothalamic obesity in humans

Hypothalamic injury from acquired structural damage due to infiltrative disease, tumor, or their treatment aftereffects frequently results in the development of an obesity syndrome characterized by a rapid, unrelenting weight gain that may be accompanied by severe hyperphagia. Weight gain occurs from the disruption of the normal homeostatic functioning of the hypothalamic centers responsible for controlling satiety and hunger and regulating energy balance with resulting hyperphagia, autonomic imbalance, reduction of energy expenditure, and hyperinsulinemia. Curtailment of weight increase has traditionally been refractory to usual dietary and lifestyle interventions. Pharmacotherapy targeting insulin secretion and augmenting sympathetic output have been attempted to promote weight loss or attenuate weight gain. In addition, case reports suggest that bariatric surgery may be an effective treatment option for these patients. Hormonal deficits are often present, and their management may also have consequences for weight control. Hypothalamic obesity confers significant morbidity and mortality, and there is a need for greater elucidation of its risk factors and pathogenesis so that more effective interventions can be developed.

Reference intervals of urinary steroid metabolites using gas chromatography-mass spectrometry in Chinese adults

BACKGROUND

Urinary steroid profiling by GC or GC-MS are established clinical tools to complement other biochemical tests in the diagnosis and investigation of a wide range of adrenocortical disorders, but normative data on adults using the more specific GC-MS are lacking. Our objective was to set up the reference intervals of commonly detected urinary steroid metabolites as well as marker metabolites seen in disease states.

METHOD

Apparently healthy adult Chinese males and females were recruited by completing health questionnaires. A 24-h urine specimen was collected from all the participants for urinary steroid profiling by GC-MS in cyclic scan mode. The analyzer was calibrated by using authentic steroid standards. Statistical methods recommended by the National Committee for Clinical Laboratory Standards were followed for setting up the reference intervals of various steroid metabolites. After outliers were excluded, the data were tested for the necessity to partition into sex-, menopausal status- and age-specific reference intervals.

RESULTS

83 males and 89 females were recruited for the study. Necessity to partition into sex-specific reference intervals was demonstrated for almost all steroid metabolites. Menopausal status and age also had a significant impact on steroid metabolite excretion, making separate reference intervals necessary.

CONCLUSIONS

We have set up the normative data on the levels of urinary steroid metabolite excretion in Chinese adults for future reference in patient management and research in steroid metabolism.

Prevalence of obesity, hyperlipemia and insulin resistance in children with suprasellar brain tumors

Weight gain is a common sequela of suprasellar tumors, referred to as hypothalamic obesity. We undertook an evaluation of obesity and metabolic aberrations among patients treated at our institute. During the 12 mo from Apr. 2005, 23 patients (10 males and 13 females) with remitted suprasellar tumors attended our clinic: 10 patients with craniopharyngioma, 7 with germinoma, 4 with optic nerve glioma and others. Of these, 12 patients (52%) were found to have obesity on the basis of percent overweight and/or percent body fat. Elevated cholesterol and/or triglyceride (TG) was found in 9 patients (39%), and insulin resistance was suspected in 7 patients (30%). Three patients exhibited strikingly elevated postprandial TG levels. All 6 patients with the growth without GH phenomenon had at least one metabolic aberration. In conclusion, the prevalence of hypothalamic obesity was nearly half in our series, and hyperlipemia and insulin resistance were also frequently found. The increased risk for metabolic aberration in growth without GH patients was suggested.

Childhood obesity and insulin resistance

Insulin resistance (IR) in childhood has importance to the understanding and prevention of the growing epidemic of insulin resistance syndrome (IRS) in adults with attendant obesity, type 2 diabetes (T2DM), atherosclerotic diseases, hypertension, gout, non-alcoholic, steato-hepatitis (NASH), gall bladder disease, nephropathy, polycystic ovarian disease (PCOS), infertility and premature senility. The severity of IR and its' complications in children unfortunately and usually progresses in their pubertal transition to adulthood; affected young children are more likely than adults to have underlying causal monogenic disorders; the sequence of natural history and events give insights into disease pathogeneses, and optimal life style choices that last are best made during the early formative years. Some features of IR in children discussed herein are: a strong tendency to low birth weight for gestational age, adverse effects of adrenarche and therapeutic steroid therapy, predisposition to premature pubarche, acanthosis nigricans, tall stature despite pituitary GH suppression, allergic diathesis, hyperandrogenism and PCOS, dyslipidemia and fatty liver disease, and diagnosis by clinical and biochemical markers of IR including insulin regulated hepatic hormonal binding proteins such as IGFBP-1. The national preoccupation with the "metabolic syndrome" T2DM and obesity, should be appropriately directed to an improved understanding of IR in children and their management, if the looming health crisis in affected adults is to be seriously addressed. The nation is facing its' first generation of children who will be less healthy and die younger than the previous generation (Marks (2005) Presentation to the American Association of Diabetes Educators 32nd Annual Meeting and Exhibition, August 10-13, Washington, DC).

Intracrine modulation of gene expression by intracellular generation of active glucocorticoids

Glucocorticoids (GC) by either up-regulating or down-regulating the expression of genes influence cellular processes in every tissue and organ of the body. The enzyme 11beta-hydroxysteroid dehydrogenase Type-1 (11beta-HSD-1) confers bioactivity upon the inactive GC cortisone (E) and prednisone (P) by converting them to cortisol (F) and prednisolone (L), respectively. We sought to investigate whether gene expression modulation by GC is under the regulation of an intracrine mechanism that determines the intracellular concentration of active GC. Human cell lines were transiently and stably co-transfected with an expression construct for 11beta-HSD-1 and a GC-responsive reporter gene and incubated with active and inactive GC. Whereas in cells that were not transfected with the expression construct for 11beta-HSD-1 inactive GC had no transcriptional activity, in both transiently and stably transfected cells E and P demonstrated a dose-dependent transcriptional activity. This transcriptional potency of both inactive GC was effectively abolished by carbenoxolone, an 11beta-HSD-1 inhibitor, and was directly related to the concentration of transfected 11beta-HSD-1. We conclude that gene expression modulation by GC is under a decisive influence of target cell 11beta-HSD-1 that modulates the intracellular concentration of active GC. The intracrine mechanism is an under-appreciated aspect of GC activity that could be a potential target for future therapies aimed at modulating GC effects at the cellular level.

Tissue Production of Cortisol by 11beta-Hydroxysteroid Dehydrogenase Type 1 and Metabolic Disease

Activation of intracellular glucocorticoid receptors is determined not only by the plasma concentrations of cortisol, under the influence of the hypothalamic-pituitary-adrenal (HPA) axis, but also by 11HSD enzymes within the target cell which interconvert cortisol with its inert metabolite cortisone. Data from cells in culture, isolated tissues, and transgenic mouse models have established that 11HSD type 1 regenerates glucocorticoids and amplifies glucocorticoid receptor activation. In humans, the rate of cortisol regeneration in peripheral tissues is of similar magnitude to adrenal secretion of cortisol at most times of day, and occurs principally in the splanchnic circulation. Approximately two-thirds of the splanchnic activity appears to reside in visceral adipose tissue, sufficient to allow visceral adipose tissue to "deliver" cortisol to the liver via the portal vein. In obesity, 11HSD1 activity in subcutaneous adipose tissue is increased, putatively explaining the link between obesity and other features of the metabolic syndrome. The regulation of 11HSD1, and the basis for its upregulation in obesity, are now being explored. Against this background, inhibition of 11HSD1 has become a major therapeutic target in metabolic syndrome. Preclinical results with novel selective 11HSD1 inhibitors are encouraging, and clinical proof of principle has been achieved with the nonselective inhibitor carbenoxolone. Although the parallels between metabolic syndrome and Cushing's syndrome were originally drawn with reference to patients with elevated plasma cortisol concentrations, it now appears that manipulating tissue concentrations of cortisol will allow the subtle level of control required for long-term therapy to reduce the risks of cardiovascular disease.

Inhibition of 11beta-hydroxysteroid dehydrogenase type 1 in obesity

Excessive glucocorticoid exposure (Cushing's syndrome) results in increased adiposity associated with dysmetabolic features (including insulin resistance, hyperlipidaemia, and hypertension). Circulating cortisol levels are not elevated in idiopathic obesity, although cortisol production and clearance are increased. However, tissue glucocorticoid exposure may be altered independently of circulating levels by 11beta-hydroxysteroid dehydrogenase type 1 (11HSD1), an enzyme which generates active glucocorticoid within tissues, including in adipose tissue. Transgenic overexpression of 11HSD1 in mice causes obesity. In human obesity, 11HSD1 is altered in a tissue-specific manner with reduced levels in liver but elevated levels in adipose, which may lead to glucocorticoid receptor activation and contribute to the metabolic phenotype. The reasons for altered 11HSD1 in obesity are not fully understood. Although some polymorphisms have been demonstrated in intronic and upstream regions of the HSD11B1 gene, the functional significance of these is not clear. In addition, there is mounting evidence that 11HSD1 may be dysregulated secondarily to factors that are altered in obesity, including substrates for metabolism, hormones, and inflammatory mediators. 11HSD1 is a potential therapeutic target for the treatment of the metabolic syndrome. 11HSD1 knockout mice are protected from diet-induced obesity and associated metabolic dysfunction. Although many specific inhibitors of 11HSD1 have now been developed, and published data support their efficacy in the liver to reduce glucose production, their efficacy in enhancing insulin sensitivity in adipose tissue remains uncertain. The therapeutic potential of 11HSD1 in human obesity therefore remains highly promising but as yet unproven.

Determination of M+4 stable isotope labeled cortisone and cortisol in human plasma by microElution solid-phase extraction and liquid chromatography/tandem mass spectrometry

A sensitive microElution solid-phase extraction (SPE) liquid chromatography/tandem mass spectrometry (LC/MS/MS) method has been developed and validated for the determination of M+4 stable isotope labeled cortisone and cortisol in human plasma. In this method, M+4 cortisone and M+4 cortisol were extracted from 0.3 mL of human plasma samples using a Waters Oasis HLB 96-well microElution SPE plate using 70 microL methanol as the elution solvent, and chromatographed on a Waters Symmetry C18 column (4.6 x 50 mm, 3.5 microm). M+9 cortisone and M+9 cortisol were used as the internal standards. A PE Sciex API 4000 tandem mass spectrometer interfaced with the liquid chromatograph via a turboionspray source was used for mass analysis and detection. The selected reaction monitoring (SRM) of precursor --> product ion transitions were monitored at m/z 365.2 [M+H](+) --> 167.0 and at m/z 367.3 [M+H](+) --> 125.1 for M+4 cortisone and M+4 cortisol, respectively. The lower limit of quantitation was 0.1 ng mL(-1) and the linear calibration range was from 0.1 to 100 ng mL(-1) for both analytes. This method demonstrated to be very reproducible and reliable.

Direct determination of the ratio of tetrahydrocortisol+allo-tetrahydrocortisol to tetrahydrocortisone in urine by LC–MS–MS

The 11beta-hydroxysteroid dehydrogenase (11beta-HSD) is responsible for the interconversion of both the hormonally inactive cortisone and the active cortisol. This enzyme activity, which has implications in the pathogenesis of numerous diseases, is reflected in the ratio of tetrahydrometabolites of cortisol (allo-tetrahydrocortisol and tetrahydrocortisol) to those of cortisone (tetrahydrocortisone). Several methods have been proposed in the literature to determine such a ratio in urine. Most of them require tedious and extensive extraction and derivatization steps and make use of gas-chromatographic techniques, including gas chromatography coupled to mass spectrometry (GC-MS). We present here an alternative approach for the direct determination of such a ratio in urine by using liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS-MS), based on a minimal sample treatment. Actually, the limit of detections (LODs) for pure standards in water permitted a simple dilution of the urine samples prior to the analysis, hence, an accurate optimization of the high performance liquid chromatography (HPLC) separation was needed in order to get rid of the severe influence of the urine matrix on the ionization efficiency. Besides, the nature of some interfering species was deeply investigated, as well as the suitability of some commercial deuterated steroids as internal standards. All these led to the final method, which was based on a HPLC separation on a C8 column and a ternary gradient water/methanol/acetonitrile. In parallel, an appropriate sample preparation was set up, which consisted of an enzymatic hydrolysis of the conjugated species and a followed 1:20 dilution. Preliminary measurements on real urine samples were performed as well.

Obesity and type 2 diabetes do not alter splanchnic cortisol production in humans

CONTEXT

Cortisol is a potent regulator of carbohydrate, fat, and protein metabolism.

OBJECTIVE

The objective of the study was to determine whether obesity alone or in combination with type 2 diabetes increases splanchnic and/or leg cortisol production.

DESIGN

Splanchnic and leg cortisol production were measured using the hepatic and leg catheterization technique combined with infusion of D4-cortisol.

SETTING

The study was conducted in a General Clinical Research Center.

PARTICIPANTS

Nine lean nondiabetic, 10 obese nondiabetic, and 11 obese diabetic subjects were studied.

INTERVENTIONS

Diabetic volunteers were withdrawn from their glucose-lowering medications before study.

MAIN OUTCOME MEASURES

Rates of total body, splanchnic and leg cortisol, and D3-cortisol production were measured.

RESULTS

Rates of splanchnic cortisol production equaled or exceeded those occurring in extrasplanchnic tissues (e.g. the adrenals) in all three groups. However, because concurrent splanchnic cortisol uptake also occurred, net splanchnic cortisol release was minimal. Splanchnic cortisol production and splanchnic D3-cortisol production (an index of splanchnic 11beta-hydroxysteroid dehydrogenase type 1 activity) did not differ among the three groups. In addition, splanchnic cortisol production did not correlate with either visceral fat or endogenous glucose production. On the other hand, splanchnic cortisol uptake was greater in the obese diabetic than lean nondiabetic subjects (25 +/- 2.9 vs. 15.3 +/- 2.5 microg/min; P < 0.05). Splanchnic, but not leg, D3-cortisol production was correlated with total body D3-cortisol production (r = 0.70; P < 0.001).

CONCLUSIONS

Although large amounts of cortisol are produced within the splanchnic bed, implying high intrahepatic glucocorticoid concentrations, rates do not differ in lean and obese nondiabetic humans and are not influenced by the presence of type 2 diabetes mellitus. On the other hand, obesity but not diabetes increases splanchnic cortisol uptake.

The human glucocorticoid receptor (GR) isoform {beta} differentially suppresses GR{alpha}-induced transactivation stimulated by synthetic glucocorticoids

The beta-isoform of human glucocorticoid receptor beta (hGRbeta) acts as a natural dominant negative inhibitor of hGRalpha-induced transactivation of glucocorticoid-responsive genes. We determined hGRbeta ability to suppress hGRalpha transactivation that was induced by commonly used synthetic glucocorticoids. HepG2/C3A cells were transiently cotransfected with GR cDNA and a glucocorticoid-responsive promoter, luciferase (MMTV-luc). Transfected cells were incubated for 16 h with glucocorticoid and luciferase. For each compound, a dose-response curve was constructed, and half-maximal effective concentrations and maximal transcriptional activities were compared. hGRbeta, at a 1:1 ratio to hGRalpha, differentially suppressed hGRalpha-induced maximal transcriptional activity stimulated by triamcinolone, dexamethasone, hydrocortisone, and betamethasone (by 96, 68, 62, and 49%, respectively) but not by methylprednisolone. The suppressive effect of hGRbeta on hGRalpha-induced transactivation was stronger at lower concentrations of all tested glucocorticoids, whereas it was blunted at higher concentrations. We conclude that the potency of the dominant negative effect of hGRbeta on hGRalpha-induced transactivation depends on both the type and the dose of the synthetic glucocorticoids in use. These results may provide helpful information concerning the selection of synthetic glucocorticoids for treatment of pathological conditions in which hGRbeta modulates the sensitivity of tissues to glucocorticoids.

11β-Hydroxysteroid dehydrogenase Type 1 as a novel therapeutic target in metabolic and neurodegenerative disease

11beta-hydroxysteroid dehydrogenase Type 1 (11HSD1) catalyses regeneration of active 11-hydroxy glucocorticoids from inactive 11-keto metabolites within target tissues. Inhibition of 11HSD1 has been proposed as a novel strategy to lower intracellular glucocorticoid concentrations, without affecting circulating glucocorticoid levels and their responsiveness to stress. Increased 11HSD1 activity may be pathogenic, for example, in adipose tissue in obesity. Experiments in transgenic mice and using prototype inhibitors in humans show benefits of 11HSD1 inhibition in liver, adipose and brain tissue in treating features of the metabolic syndrome and cognitive dysfunction with ageing. The clinical development of potent selective 11HSD1 inhibitors is now a high priority.

Increased glucocorticoid receptor and 11{beta}-hydroxysteroid dehydrogenase type 1 expression in hepatocytes may contribute to the phenotype of type 2 diabetes in db/db mice

Excess tissue glucocorticoid action may contribute to the hyperglycemia and insulin resistance associated with type 2 diabetes, but the associated mechanisms are poorly understood. 11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD1) converts inactive 11-dehydrocorticosterone into active corticosterone, thus amplifying glucocorticoid receptor-mediated tissue glucocorticoid action, particularly in the liver. To examine the role of tissue glucocorticoid action in type 2 diabetes, we analyzed expression of glucocorticoid receptor and 11beta-HSD1 and their regulation by endogenous hormones in vivo and in vitro in hepatocytes from db/db mice (a model of type 2 diabetes). We observed positive relations between expression of both glucocorticoid receptor and 11beta-HSD1 in liver and insulin sensitivity and expression of PEPCK mRNA in db/db mice and db/+ controls. Increased expression of glucocorticoid receptor and 11beta-HSD1 in the liver of db/db mice was correlated with elevated circulating levels of corticosterone, insulin, and blood glu-cose. Treatment of db/db mice with glucocorticoid antagonist RU486 reversed the increases in the expression of glucocorticoid receptor and 11beta-HSD1 within the liver and attenuated the phenotype of type 2 diabetes. Addition of corticosterone to db/db mouse primary hepatocytes activated expression of glucocorticoid receptor, 11beta-HSD1, and PEPCK, and these effects were abolished by RU486. Incubation of primary hepatocytes with increasing concentrations of glucose caused dose-dependent increases in glucocorticoid receptor and 11beta-HSD1 expression, whereas insulin did not affect the expression of 11beta-HSD1 and glucocorticoid receptor in primary hepatocytes. These findings suggest that activation of glucocorticoid receptor and 11beta-HSD1 expression within the liver may contribute to the development of type 2 diabetes in db/db mice.

Cortisol and cortisone analysis in serum and plasma by atmospheric pressure photoionization tandem mass spectrometry

OBJECTIVES

Cortisol metabolism is controlled by 11beta-hydroxysteroid dehydrogenase (11beta-HSD) isoenzymes, which interconvert cortisol and cortisone. Accurate measurement of the cortisol and cortisone concentrations and their ratio provide useful information about 11beta-HSD activity.

METHODS

Cortisol and cortisone were extracted with methyl-tert-butyl ether from 100 microl of serum or plasma. The extract was evaporated, reconstituted with mobile phase, and analyzed by tandem mass spectrometry using a photoionization interface. The transitions monitored were: m/z 363 to 121 and 363 to 97 for cortisol, 361 to 163 and 361 to 105 for cortisone.

RESULTS

Within-run and between-run coefficients of variation were less than 6% and 12%; 14% and 22%; 11% and 21% for cortisol, cortisone, and their ratio, respectively. The limit of detection was 1 microg/l for cortisol and 5 microg/l for cortisone. Normal ranges for cortisol and cortisone concentration and for their ratio in plasma (n = 120) determined as the central 95% were 33-246 microg/l for cortisol, 8-27 microg/l for cortisone, and 0.081-0.301 for the cortisone/cortisol ratio.

CONCLUSIONS

We developed a simple sensitive method for cortisol and cortisone analysis in plasma and serum that uses a small sample volume. The method is very specific, fast, does not have any known interference, and is useful for diagnosis of variety of disease and pathologic conditions.

11beta-hydroxysteroid dehydrogenase type 1: a tissue-specific regulator of glucocorticoid response

11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD1) interconverts inactive cortisone and active cortisol. Although bidirectional, in vivo it is believed to function as a reductase generating active glucocorticoid at a prereceptor level, enhancing glucocorticoid receptor activation. In this review, we discuss both the genetic and enzymatic characterization of 11beta-HSD1, as well as describing its role in physiology and pathology in a tissue-specific manner. The molecular basis of cortisone reductase deficiency, the putative "11beta-HSD1 knockout state" in humans, has been defined and is caused by intronic mutations in HSD11B1 that decrease gene transcription together with mutations in hexose-6-phosphate dehydrogenase, an endoluminal enzyme that provides reduced nicotinamide-adenine dinucleotide phosphate as cofactor to 11beta-HSD1 to permit reductase activity. We speculate that hexose-6-phosphate dehydrogenase activity and therefore reduced nicotinamide-adenine dinucleotide phosphate supply may be crucial in determining the directionality of 11beta-HSD1 activity. Therapeutic inhibition of 11beta-HSD1 reductase activity in patients with obesity and the metabolic syndrome, as well as in glaucoma and osteoporosis, remains an exciting prospect.

11 beta-hydroxysteroid dehydrogenase type 1 in obesity and the metabolic syndrome

11 beta-Hydroxysteroid dehydrogenase type 1 (11HSD1) catalyses the in vivo conversion of inactive to active glucocorticoids. It is a widespread, highly regulated enzyme which amplifies the ligand available for intracellular glucocorticoid receptors. Excessive glucocorticoid exposure causes central obesity, hypertension, dyslipidaemia and insulin resistance, as seen with elevated plasma cortisol in Cushing's syndrome. Transgenic mice over-expressing 11HSD1 in their white adipose tissue are obese, hypertensive, dyslipidaemic and insulin resistant. Further, 11HSD1 knockout mice are protected from these metabolic abnormalities. In human idiopathic obesity, circulating cortisol levels are not elevated but 11HSD1 mRNA and activity is increased in subcutaneous adipose. The impact of increased adipose 11HSD1 on pathways leading to metabolic complications remains unclear in humans. Pharmacological inhibition of 11HSD1 has been achieved in liver with carbenoxolone, which enhances hepatic insulin sensitivity. Newer selective 11HSD1 inhibitors are in development, which may achieve reduced cortisol action in adipose tissue and confer therapeutic benefit in obese patients.