Endocrine Abstracts

Patients with glucocorticoids (GC) excess develop central obesity, insulin resistance and hepatic steatosis in up to 20% of cases. Current dogma suggests that GCs cause insulin resistance in all tissues. However, we have previously demonstrated that GCs induce insulin sensitisation in adipose tissue in vitro, whilst causing insulin resistance in skeletal muscle. In rodent hepatocytes, GCs enhance insulin stimulated lipogenesis but studies in human hepatocytes have not...

The potent effects of glucocorticoids (GCs) upon carbohydrate metabolism are well described. However, their actions upon lipid metabolism are poorly characterized. Patients with GC excess (Cushing’s syndrome) develop central obesity, insulin resistance and hepatic steatosis in up to 20% of cases. The A-ring reductases (5α-reductase type 1 [5αR1] and type 2 [5αR2]), inactivate cortisol as well as generate dihydrotestosterone (DHT) from testosterone (T) and a...

Glucocorticoid excess is characterized by increased adiposity, skeletal myopathy and insulin resistance. Although there is a strong inverse correlation between intramuscular triglyceride (IMTG) levels and insulin sensitivity, the impact of glucocorticoids upon the processes that regulate skeletal muscle lipid metabolism has not been explored.Mouse C2C12 skeletal myocytes were grown to confluence and differentiated into myotubes in chemically defined medi...

Glucocorticoid (GC) excess is characterized by central obesity, insulin resistance and in some cases, type 2 diabetes mellitus. Whilst it is accepted that GCs cause insulin resistance, both insulin and GCs act synergistically to promote adipocyte differentiation. We have previously shown that acute treatment (24 h) with GCs enhances insulin signalling in human adipocytes. We hypothesise that the generation of cortisol from inactive cortisone by 11β-hydroxysteroid dehydrog...

The epidemic of obesity, insulin resistance and type 2 diabetes has heightened the need to understand the mechanisms that contribute to their pathogenesis. Endogenous glucocorticoid (GC) production and metabolism have been implicated based upon parallels with Cushing’s syndrome. The interaction between GC metabolism and insulin sensitivity in the context of significant weight loss has not been explored. 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1) that gen...

Intra-abdominal adiposity is associated with insulin resistance and increased cardiovascular morbidity and mortality. Obesity occurs as a consequence of increased adipocyte size (hypertrophy) and number (differentiation or hyperplasia). Whilst differences in gene expression between omental (om) and subcutaneous (sc) adipose tissue have been described, the molecular mechanisms that underpin the differences in adipose tissue biology and the depot specific metabolic risks that th...

The adrenal steroid dehydroepiandrosterone (DHEA) and its sulphate ester, DHEAS have been shown to oppose the effects of glucocorticoids, thereby producing beneficial effects on insulin sensitivity in rodent models of diabetes and obesity and in hypoadrenal patients. Glucocorticoids, key regulators of adipose differentiation and insulin sensitivity, are reactivated locally by 11β-hydroxysteroid dehydrogenase type (11β-HSD1) oxoreductase activity, which increases with...

Type 2 diabetes manifests when pancreatic β-cells secrete inadequate insulin in response to elevated glucose. A known culprit in metabolic diseases is excessive exposure to glucocorticoids (GCs). GCs increase hepatic gluconeogenesis, decrease insulin sensitivity in skeletal muscle and adipose tissue and suppress the development of β-cells. In rodents, inactive GC 11-dehydrocorticosterone (A) is converted to active corticosterone (B) by the enzyme 11β-hydroxyster...

The metabolic syndrome, which encompasses features of obesity, insulin resistance, dyslipidaemia and hypertension, has been associated with excessive glucocorticoid (GC) exposure. The pancreas is a target of the adverse affects of GC action, resulting in β-cell damage and reduced glucose-stimulated insulin secretion (GSIS). 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1) catalyses the in vivo conversion of inactive to active glucocorticoids (cortisone E/11-de...

Dehydroepiandrosterone (DHEA) and its sulphate ester DHEAS, have been shown to oppose the effects of glucocorticoids in vivo, thus producing beneficial effects on insulin sensitivity in rodent models of diabetes and obesity as well as in hypoadrenal patients. Glucocorticoids play a key role in regulating fat metabolism and distribution and are reactivated locally by 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1) oxoreductase activity, which increases with ...