Orexigenic Neuropeptide 26RFa: New Evidence for an Adaptive Profile of Appetite Regulation in Anorexia Nervosa

Context: Restrictive anorexia nervosa (AN) presents an adaptive appetite regulating profile including mainly high levels of ghrelin. Because this adaptive mechanism is not effective on food intake, other appetite-regulating peptides need to be explored. 26RFa is a hypothalamic neuropeptide that stimulates appetite, gonadotropin release, and bone metabolism. Objective: The objective of the study was to evaluate the circadian levels of 26RFa in AN patients compared with healthy subjects, other eating disorders, and constitutional thinness (CT). Design and Settings: This was a cross-sectional study performed in an endocrine unit and an academic laboratory. Investigated Subjects: Five groups of age-matched young women were included in the study: 19 restrictive AN, 10 AN with bingeing/purging episodes, 14 with CT, 10 bulimic, and 10 normal-weight controls. Main Outcome Measures: Twelve-point circadian profiles of plasma 26RFa levels were measured in each subject. Results: Significant circadian variations of 26 RFA were noticed in controls with higher values in the morning and abrupt decrease at noon. Twenty-four-hour mean 26RFa levels were significantly increased in restrictive AN and AN with bingeing/purging episodes (P < 0.001), predominantly in the afternoon and evening when compared with controls. Preprandial rises of 26 RFA were noticed in AN patients. Mean 26RFa levels trend to be higher in CT than in controls (P = 0.06) and significantly lower than in AN. The bulimic patients presented a circadian profile of 26RFa similar to that of controls. Conclusion: High levels of circulating 26RFa observed in AN patients might reflect an adaptive mechanism of the organism to promote energy intake and to increase fat stores in response to undernutrition. (J Clin Endocrinol Metab 97: 2012-2018, 2012)