Greisa Vila, Michael Krebs, Michaela Riedl, Sabina M Baumgartner-Parzer, Martin Clodi, Christina Maier, Giovanni Pacini and Anton Luger
Background and aim
Several basic science studies support the existence of non-genomic glucocorticoid signaling in pancreas, liver, and adipocytes, but its clinical relevance has not yet been elucidated. This study aimed at investigating the rapid effects of hydrocortisone on the human metabolic response to glucose.
Subjects and methods
In a randomized placebo-controlled crossover study, ten healthy men received an i.v. bolus of 0.6 mg/kg hydrocortisone once and placebo once 4 min before the administration of 330 mg/kg glucose. Cortisol, glucose, insulin, C-peptide, ghrelin, and peptide YY (PYY) levels were measured during the following 3 h. Minimal model analysis was performed for evaluating the metabolic response.
Hydrocortisone attenuated the rise in plasma glucose during the initial 15 min following glucose administration (P=0.039), and it led to lower glucose levels during the first 2 h (P=0.017). This was accompanied by enhanced circulating insulin (P=0.02) and C-peptide (P=0.03) levels during the initial 15 min, and a 35% increase in the first-phase β-cell function (P=0.003). Hydrocortisone decreased PYY concentrations during the initial 30 min (P=0.014), but it did not affect the ghrelin response to glucose.
One i.v. bolus of hydrocortisone induces rapid effects on carbohydrate metabolism increasing the first-phase β-cell function. The modulation of PYY plasma levels suggests the possible non-genomic effects of glucocorticoids on appetite-regulatory hormones.
Marie Helene Schernthaner-Reiter, Dominik Kasses, Christina Tugendsam, Michaela Riedl, Slobodan Peric, Gerhard Prager, Michael Krebs, Miriam Promintzer-Schifferl, Martin Clodi, Anton Luger and Greisa Vila
Growth differentiation factor 15 (GDF15) is a cardiovascular biomarker belonging to the transforming growth factor-β superfamily. Increased GDF15 concentrations are associated with insulin resistance, diabetes and obesity. We investigated the physiological effects of meal composition and obesity on the regulation of systemic GDF15 levels.
Lean (n = 8) and obese (n = 8) individuals received a carbohydrate- or fat-rich meal, a 75 g oral glucose load (OGTT) or short-term fasting. OGTTs were performed in severely obese patients (n = 6) pre- and post-bariatric surgery.
Circulating serum GDF15 concentrations were studied in lean and obese individuals in response to different meals, OGTT or short-term fasting, and in severely obese patients pre- and post-bariatric surgery. Regulation of GDF15 mRNA levels and protein release were evaluated in the human hepatic cell line HepG2.
GDF15 concentrations steadily decrease during short-term fasting in lean and obese individuals. Carbohydrate- and fat-rich meals do not influence GDF15, whereas an OGTT leads to a late increase in GDF15 levels. The positive effect of OGTT on GDF15 levels is also preserved in severely obese patients, pre- and post-bariatric surgery. We further studied the regulation of GDF15 mRNA levels and protein release in HepG2, finding that glucose and insulin independently stimulate both GDF15 transcription and secretion.
In summary, high glucose and insulin peaks upregulate GDF15 transcription and release. The nutrient-induced increase in GDF15 levels depends on rapid glucose and insulin excursions following fast-digesting carbohydrates, but not on the amount of calories taken in.