Lack of Postprandial Peak in Brain-Derived Neurotrophic Factor in Adults with Prader-Willi Syndrome

CONTEXT Prader-Willi syndrome (PWS) is characterized by severe hyperphagia. Brain-derived neurotrophic factor (BDNF) and leptin are reciprocally involved in energy homeostasis. OBJECTIVES To analyze the role of BDNF and leptin in satiety in genetic subtypes of PWS. DESIGN Experimental study. SETTING University hospital. SUBJECTS 90 adults: 30 PWS patients; 30 age-sex-BMI-matched obese controls; and 30 age-sex-matched lean controls. INTERVENTIONS Subjects ingested a liquid meal after fasting ≥10 hours. MAIN OUTCOME MEASURES Leptin and BDNF levels in plasma extracted before ingestion and 30', 60', and 120' after ingestion. Hunger, measured on a 100-point visual analogue scale before ingestion and 60' and 120' after ingestion. RESULTS Fasting BDNF levels were lower in PWS than in controls (p = 0.05). Postprandially, PWS patients showed only a truncated early peak in BDNF, and their BDNF levels at 60' and 120' were lower compared with lean controls (p<0.05). Leptin was higher in PWS patients than in controls at all time points (p<0.001). PWS patients were hungrier than controls before and after eating. The probability of being hungry was associated with baseline BDNF levels: every 50-unit increment in BDNF decreased the odds of being hungry by 22% (OR: 0.78, 95%CI: 0.65-0.94). In uniparental disomy, the odds of being hungry decreased by 66% (OR: 0.34, 90%CI: 0.13-0.9). Postprandial leptin patterns did no differ among genetic subtypes. CONCLUSIONS Low baseline BDNF levels and lack of postprandial peak may contribute to persistent hunger after meals. Uniparental disomy is the genetic subtype of PWS least affected by these factors.