ACTH and cortisol responses to ghrelin and DDAVP in patients with Cushings disease (CD)
Dragana Miljic, Mirjana Doknic, Sandra Pekic, Marina Djurovic, Zorana Penezic, Svetozar Damjanovic, Djuro Macut, Mirjana Sumarac-Dumanovic, Bojana Popovic, Mohammad Ghatei & Vera Popovic
Aim of this study was to investigate head to head ACTH and cortisol responses to DDAVP and ghrelin in patients with CD. Study was approved by the local ethics committee and informed consent obtained. Nine patients with CD were submitted to ghrelin 1 μg/kg and DDAVP 10 μg bolus iv administration on two separate occasions. Blood was sampled at 0.15, 30, 45, 60, 90 min. for ACTH (ELISA) and cortisol (RIA, Cis, Bio International, France) measurements.
Ghrelin induced significant ACTH (65.3±54.7 vs 188.6±128.8 pg/ml; P<0.05) and cortisol responses (642.5±357.2 vs 856.0±447.4 nmol/l; P=0.05) in our patients. After DDAVP there was also a significant increase in ACTH (53.5±49.3 vs 227.6±359.2 pg/ml; P=0.05) and cortisol levels (444.5±249.2 vs 658.8±369.6 nmol/l; P<0.05). When compared peak ACTH and cortisol values after both tests were not statistically different. Integrated ACTH (pg/ml.min) (ghrelin:11 677.7±7 253.6 vs DDAVP: 12 470.4±16 911.2) and cortisol (nmol/l.min) secretion (ghrelin: 81 810.6±49 437.6 vs DDAVP: 64 677.0±38 399.9) were not significantly different after two tests.
Although limited by size our study shows that ghrelin compared to DDAVP induces similar cortisol and ACTH responses. The mechanisms of ghrelin action on ACTH and cortisol secretion in patients with CD merit further investigation.