Prader-Willi syndrome (PWS) is the most common cause of syndromic obesity. There are many contributors to obesity in PWS, hyperphagia behavior being one of them. The underlying mechanisms for hyperphagia have not yet been elucidated; however, developing effective preventive or therapeutic modalities requires a clear understanding. In this study deletion-type obese PWS (n=9), UPD-type obese PWS (n=7), BMI-matched obese controls (n=16) and healthy lean controls (n=25) were investigated for ghrelin, oxytocin and BDNF (brain-derived neurotrophic factor) levels in fasting serum samples. Ghrelin and oxytocin levels in two PWS subgroups were similar, but significantly lower than both control groups, whereas BDNF levels were comparable in all four groups. Levels of these three hormones were also comparable among PWS patients (n=16), obese and healthy controls. As ghrelin levels in the PWS group were not increased, these results suggest that decreased oxytocin levels rather than increased ghrelin levels might contribute to hypothalamic hyperphagia behavior in PWS.

Keywords: ghrelin, oxytocin, BDNF, Prader-Willi syndrome, deletion, uniparental disomy