Endocrine Abstracts

Background: The 5α-reduced glucocorticoid, 5α-tetrahydrocorticosterone (5α-THB), displays a dissociated steroid profile exhibiting anti-inflammatory effects in a murine model of thioglycollate-induced peritonitis but failing to induce adverse metabolic effects caused by corticosterone. We assessed the topical anti-inflammatory properties of 5α-THB in a model of irritant dermatitis. Given the adverse effects of steroids on cutaneous wound healing, we also in...

Background: 5α-reductase 1 (5αR1) metabolises steroids such as glucocorticoids and androgens, and is highly expressed in murine liver. Genetic disruption of 5αR1 leads to adverse metabolic changes in mice. We hypothesised that dutasteride, a 5αR inhibitor, induces insulin resistance in mice, as in humans, and this effect is underpinned by increased hepatic glucocorticoid action; an experimental paradigm was set up using A-348441, a liver-selective glucocort...

Human plasma contains both cortisol (F) and corticosterone (B). B has been largely neglected in humans as it is 10–20 times less abundant however previous studies suggest B and F have differential tissue-specific actions. Compared with F, B has an enhanced response to ACTH, relatively higher concentrations in brain and CSF and differential transmembrane trafficking by ATP-binding cassette (ABC) transporters. Plasma F is bound to corticosteroid-binding globulin (CBG) and a...

Background: Using a deuterated tracer (D4-cortisol) to measure cortisol regeneration from cortisone in vivo we have quantified tissue-specific 11βHSD1 activity in health and disease, and acute regulation eg by insulin. These studies relied on tracer enrichment in the total plasma cortisol pool, assuming rapid equilibration between free and protein-bound pools. Slower equilibration would result in underestimation of enzyme activity, and has implications for the co...

5α-Reductase (5αR) inhibitors decrease prostatic dihydrotestosterone in benign prostatic hyperplasia (BPH) treatment; finasteride inhibits 5αR type 2, while dutasteride inhibits 5αR1 and 2. 5αRs, especially 5αR1, are also expressed in metabolic tissues regulating actions of androgens and other substrates, including glucocorticoids.Hypothesis: 5αR1 inhibition with dutasteride induces metabolic dyshomeostasis.<p class...

5α-Reductase 1 (5aR1) catalyses A-ring reduction of glucocorticoids and androgens, predominantly in liver and modulates steroid hormone action. We previously demonstrated transgenic disruption of 5aR1 predisposes mice to developing fatty liver. Here we tested whether 5aR1 disruption increases susceptibility to the development of liver injury, using the carbon tetrachloride induced liver fibrosis model.Male 5aR1−/− (KO) mice and wild-type...

Tissue cortisol levels are amplified by the enzyme 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1). In mice, transgenic overexpression of 11β-HSD1 causes the metabolic syndrome, consequently 11β-HSD1 inhibitors are a promising therapeutic target. However, determining the importance of 11β-HSD1 in humans has proved more complicated, in part due to difficulty quantifying in vivo activity. We hypothesized that cortisol regeneration by 11β-H...

Background & Aims: Observational studies implicate glucocorticoid excess, principally due to altered steroid metabolism in target tissues, in both the insulin resistance and liver fat accumulation that accompanies type 2 diabetes. To test the contribution of glucocorticoid signalling to metabolic dysfunction we blocked cortisol secretion (with metyrapone) and action (with the GR antagonist mifepristone) simultaneously in men with type 2 diabetes ± fatty liver.<p c...

Background: Testosterone deficiency is common in obesity and in type 2 diabetes mellitus. It is hypothesised that the expanded adipose pool, which is the major source of aromatase in men, depletes testosterone levels by excess conversion to estradiol. Individuals with either the GG rs2470152 polymorphism in intron 1 or a high number of TTTA repeats in intron 4 of CYP19 are known to have greater aromatase activity with demonstrable effects upon plasma estradiol and osteoporosis...

Inhibiting cortisol regeneration by 11β-HSD1 is a promising therapy for type two diabetes. In obesity, 11β-HSD1 activity is increased in adipose tissue but decreased in the liver, the latter putatively mediated by hyperinsulinaemia. We tested whether insulin sensitisation with metformin regulates 11β-HSD1 activity in whole body and in liver in obesity.Five obese men (age 48±5 years, BMI 39.8±3.6 kg/m2) participated in ...