Endocrine Abstracts

Background: The detrimental effect of excessive obesity on insulin resistance has been well established. The expansion of adipose tissue is closely dependent on two processes: adipogenesis and angiogenesis and the Wnt signalling pathway has been reported to affect both. In adipose tissue the Wnt signalling pathway functions in a converse manner: increasing commitment of mesenchymal stem cells to preadipocytes and inhibiting differentiation of preadipocytes to mature adipocytes...

Hypercortisolaemia (Cushing’s Syndrome) is characterised by abdominal fat accumulation and gluteofemoral fat loss. The mechanisms underpinning this fat mass redistribution are unknown. Adipose tissue blood flow (ATBF) and net fatty acid release rate (lipolysis) are important determinants of depot-specific fat mass. We hypothesized that hypercortisolaemia may result in increased femoral ATBF and lipolysis promoting gluteofemoral fat mass loss. We recruited nine healthy mal...

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...

6-Phosphogluconate dehydrogenase (6PGDH) is the third enzyme of the oxidative phase of the pentose phosphate pathway. The cytosolic form of this pathway is well characterised, but the details and significance of the endoplasmic reticulum (ER) version are only beginning to be understood. We have previously identified hexose-6-phosphate dehydrogenase (H6PDH), which catalyses the first two steps of this pathway within the lumen of the ER, as a pivotal regulator of ER reductases s...

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...

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...

Glucocorticoids (GC) have potent actions upon human adipose tissue, promoting adipocyte differentiation, inhibiting preadipocyte proliferation and inducing lipolysis to generate free fatty acids (FFA) and glycerol through a putative action upon hormone sensitive lipase (HSL). FFA have been strongly implicated in the pathogenesis of insulin resistance, yet the molecular mechanisms that cause GC induced lipolysis are not clear. Recently, several novel lipases have been identifie...

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 GCs cause tissue specific changes in insulin sensitivity, enhancing insulin signalling in human adipose tissue in contrast to muscle.TRB3, a mammalian homolog of <i...

Insulin resistance and androgen excess are the cardinal features of polycystic ovary syndrome (PCOS). The severity of hyperandrogenism and metabolic dysfunction in PCOS are closely correlated, but underlying mechanisms remain poorly understood. Aldoketoreductase type 1C3 (AKR1C3) is an important source of adipose androgen generation, activating androstenedione to testosterone (T). We postulated that AKR1C3 plays a critical role linking androgen metabolism and...

Patients with GC excess (Cushing’s syndrome) develop central obesity, insulin resistance and hepatic steatosis. The A-ring reductases (5α-reductase type 1 (5αR1) and 2 (5αR2)) generate dihydrotestosterone from testosterone, but importantly also inactivate cortisol and are highly expressed in human liver. We propose that 5αR may regulate GC exposure and therefore may modulate metabolic phenotype in human liver.Primary human hepato...