Endocrine Abstracts

The phenotypic similarities between patients with Cushing’s syndrome and obesity have highlighted the potential pathogenic role of glucocorticoids in obesity / metabolic syndrome. However circulating cortisol levels in these conditions are normal. At a tissue specific level, the enzyme 11β-hydroxysteroid dehydrogenase (11β-HSD) controls cortisol availability to the glucocorticoid receptor (GR). In liver and adipose tissue, the type 1 isoform alone is expressed (...

Harvey Cushing’s work informed us of the deleterious consequences of circulating cortisol excess – hypertension, osteoporosis and obesity that contributes to diabetes and premature mortality. Conversely, Hench, Kendall and Reichstein were Nobel Laureates in Physiology 1950 for the discovery of cortisone and demonstrating efficacy in patients with Rheumatoid Arthritis – in effect the birth of the anti-inflammatory actions of glucocorticoids.<p class="abstext"...

Patients with glucocorticoid (GC) excess, Cushing’s syndrome, develop a classical phenotype characterized by insulin resistance and central obesity. Whilst it is clear that GCs are essential for adipocyte differentiation, their impact upon many of the processes that regulate lipid accumulation has not been explored in detail. De novo lipogenesis involves carboxylation of acetyl CoA to malonyl-CoA by acetyl CoA carboxylase (ACC), which is subsequently converted to p...

The high dose short Synacthen (corticotropin) test (SST) is widely used to investigate suspected secondary adrenal insufficiency but concern remains about falsely reassuring results with potentially serious clinical consequences.In order to evaluate the long-term safety of the SST, we retrospectively evaluated the clinical outcome in 178 patients who achieved 30-minute cortisol values in the lowest 15th percentile of normal healthy responses. This subgro...

Glucocorticoid excess, Cushing's syndrome, is a recognised cause of insulin resistance and in some cases diabetes mellitus. In addition, patients develop reversible central obesity. However, the exact mechanisms that underpin the development of glucocorticoid mediated insulin resistance and central obesity are not known. We have hypothesized that at a cellular level, the tissue specific generation of cortisol from inactive cortisone through the action of 11beta-hydroxysteroid ...

Prostanoids have been elucidated as potent adipogenic hormones. Cyclooxygenase (PTGS) is the rate-limiting enzyme of prostanoid biosynthesis and its product, prostaglandin (PG) H2 is a precursor of PGE2, PGF2, PGD2 and PGI2. PGH2 is also metabolised by prostaglandin D-synthase (PTGDS) to PGD2 which spontaneously converts to PGJ2 or can be enzymatically converted to PGF2alpha by AKR1C3. These two metabolites have opposite effect on adipogenesis; PGF2alpha is a PPARgamma antagon...

Glucocorticoids are an important adipogenic factor. In man, circulating cortisol excess causes visceral obesity, but in simple obesity glucocorticoid levels are usually normal. However, in adipose tissue cortisol availability to bind to the glucocorticoid receptor (GR) is modulated by 11 beta-hydroxysteroid dehydrogenase type 1 (11 beta-HSD1). Human preadipocytes display both dehydrogenase (cortisol to cortisone) and oxo-reductase (cortisone to cortisol) activity. Recent genet...

The global epidemic of obesity has heightened the need to understand the mechanisms that underpin its pathogenesis. Clinical observations in patients with Cushing's syndrome have highlighted the link between cortisol and central obesity. However, whilst circulating cortisol levels are normal or reduced in obesity, local regeneration of cortisol, from inactive cortisone, by 11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD1) has been postulated as a pathogenic mechanism. W...

Patients with Cushing's syndrome develop florid, but reversible central obesity. However, circulating cortisol levels are not elevated in simple obesity. Within human adipose tissue, the enzyme 11 beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD1) is highly expressed and converts inactive glucocorticoid, cortisone to active cortisol. Rodents over-expressing 11beta-HSD1 in adipocytes develop central obesity exclusively as a result of increased adipocyte size. Whilst it has ...

The most robust biochemical marker for the diagnosis of PCOS is hyperandrogenism (androstenedione, testosterone), thought to originate from the ovaries and/or adrenals. However the change in circulating androgen/LH ratios with increasing body mass in women with PCOS suggests the autocrine generation of androgens within adipose tissue itself. The enzyme 17beta hydroxysteroid dehydrogenase (17betaHSD) which has seven human isoforms is an important regulator of sex steroid metabo...