Marked GH secretion after ghrelin alone or combined with GH-releasing hormone (GHRH) in obese patients

Summary objectives Ghrelin is a 28‐amino‐acid peptide, predominantly produced by the stomach. It displays a strong GH‐releasing activity mediated by the hypothalamus–pituitary GH secretagogue (GHS)‐receptor (GHS‐R). There are different studies that suggest the importance of ghrelin in feeding and weight homeostasis. In obesity there is a markedly decreased GH secretion. For both children and adults, the greater the body mass index (BMI), the lower the GH response to provocative stimuli, including the response to GHRH. However, the response to the natural GH secretaogogue ghrelin is unclear at the present time. The aim of the present study was to evaluate the GH response to ghrelin alone or combined with GHRH in a group of obese patients, in order to further understand the deranged GH secretory mechanisms in obesity and to clarify the mechanism of action of ghrelin. patients and measurements Six obese female patients (31 ± 3·4 years) with a BMI of 36·1 ± 7·7 kg/m2 were studied. As a control group, six normal nonobese female subjects of similar age and sex were studied. Four tests were performed: placebo, GHRH [1 µg/kg, no more than 100 µg, intravenous (i.v.)], ghrelin (1 µg/kg, no more than 100 µg, i.v.) and GHRH (1 µg/kg, no more than 100 µg, i.v.) plus ghrelin (1 µg/kg, no more than 100 µg, i.v.). Blood samples were taken at appropriate intervals for determination of GH. Statistical analyses were performed by Wilcoxon and by Mann–Whitney tests. results After GHRH, the median peak GH secretion in obese patients was 2·4 µg/l (range 0·9–8·9 µg/l). Ghrelin‐induced GH secretion showed in obese patients a median peak of 24·4 µg/l (range 7·4–85·0 µg/l), significantly greater than the response after GHRH (P