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.
Florian W Kiefer, Yvonne Winhofer, Donato Iacovazzo, Márta Korbonits, Stefan Wolfsberger, Engelbert Knosp, Franz Trautinger, Romana Höftberger, Michael Krebs, Anton Luger and Alois Gessl
Carney complex (CNC) is an autosomal dominant condition caused, in most cases, by an inactivating mutation of the PRKAR1A gene, which encodes for the type 1 alpha regulatory subunit of protein kinase A. CNC is characterized by the occurrence of endocrine overactivity, myxomas and typical skin manifestations. Cushing syndrome due to primary pigmented nodular adrenocortical disease (PPNAD) is the most frequent endocrine disease observed in CNC.
Here, we describe the first case of a patient with CNC and adrenocorticotropic hormone (ACTH)-dependent Cushing disease due to a pituitary corticotroph adenoma. Loss-of-heterozygosity analysis of the pituitary tumour revealed loss of the wild-type copy of PRKAR1A, suggesting a role of this gene in the pituitary adenoma development.
PRKAR1A loss-of-function mutations can rarely lead to ACTH-secreting pituitary adenomas in CNC patients. Pituitary-dependent disease should be considered in the differential diagnosis of Cushing syndrome in CNC patients.
Peter Wolf, Johanna Mayr, Hannes Beiglböck, Paul Fellinger, Yvonne Winhofer, Marko Poglitsch, Alois Gessl, Alexandra Kautzky-Willer, Anton Luger and Michael Krebs
In patients suffering from primary adrenal insufficiency (AI) mortality is increased despite adequate glucocorticoid (GC) and mineralocorticoid (MC) replacement therapy, mainly due to an increased cardiovascular risk. Since activation of the renin–angiotensin–aldosterone system (RAAS) plays an important role in the modulation of cardiovascular risk factors, we performed in-depth characterization of the RAAS activity.
Eight patients with primary AI (female = 5; age: 56 ± 21 years; BMI: 22.8 ± 2 kg/m2; mean blood pressure: 140/83 mmHg; hydrocortisone dose: 21.9 ± 5 mg/day; fludrocortisone dose: 0.061 ± 0.03 mg/day) and eight matched healthy volunteers (female = 5; age: 52 ± 21 years; BMI: 25.2 ± 4 kg/m2; mean blood pressure:135/84 mmHg) were included in a cross-sectional case–control study. Angiotensin metabolite profiles (RAS-fingerprints) were performed by liquid chromatography mass spectrometry.
In patients suffering from primary AI, RAAS activity was highly increased with elevated concentrations of renin concentration (P = 0.027), angiotensin (Ang) I (P = 0.022), Ang II (P = 0.032), Ang 1-7 and Ang 1-5. As expected, aldosterone was not detectable in the majority of AI patients, resulting in a profoundly suppressed aldosterone-to-AngII ratio (AA2 ratio, P = 0.003) compared to controls. PRA-S, the angiotensin-based marker for plasma renin activity, correlated with plasma renin activity (r = 0.983; P < 0.01) and plasma renin concentration (r = 0.985; P < 0.001) and was significantly increased in AI patients.
AI is associated with a unique RAAS profile characterized by the absence of aldosterone despite strongly elevated levels of angiotensin metabolites, including the potent vasoconstrictor AngII. Despite state-of-the-art hormone replacement therapy, the RAAS remains hyperactivated. The contribution of Ang II in cardiovascular diseases in AI patients as well as a potential role for providing useful complementary information at diagnosis and follow up of AI should be investigated in future trials.