Protein meal-stimulated pancreatic polypeptide secretion in Prader-Willi syndrome of adults

Children with Prader-Willi syndrome (PWS) are characterized by obesity, hyperphagia, hypogonadism, and mental retardation with underlying hypothalamic dysfunction and are known to have blunted or absent pancreatic polypeptide (PP) secretion in response to protein meals. In this communication, adults (26 +/- 3 years of age) with PWS were compared with age-matched normal obese and normal weight controls in regards to plasma glucose, insulin, PP, cholecystokinin (CCK), cholesterol, and triglyceride after a high protein meal. Compared with normal weight controls, adults with PWS showed a smaller and delayed rise in plasma insulin, and relatively smaller and delayed PP elevation whereas obese controls revealed hyperglycemia, markedly higher insulin, and moderately higher PP, cholesterol, and triglyceride levels than those with PWS. There was a small increment of CCK levels after a protein meal in all groups of adults. After a protein meal, the molar ratio of PP to CCK doubled in normal weight and PWS groups, and this ratio tripled in the normal obese group, suggesting no reduced PP secretion in PWS in response to CCK stimulation. PP hyposecretion in PWS thus appears to be a part of multiple endocrinopathy associated with hypothalamic dysfunction.