Assessment of neuropeptide Y, leptin and leptin-receptor concentrations in teenagers suffering from anorexia nervosa

Abstract

Anorexia nervosa (AN) is the third most common chronic disorder affecting adolescents and is associated with high mortality risk. The predominant symptom of anorexia nervosa is persistent and intentional striving to achieve weight loss initiated and/or sustained by the patient, leading to cachexia. Until now the cause of the condition remains unknown, but seems to be multifactoral. Patients with AN develop multi-organ complications and endocrine disorders affecting multiple disturbances of energy metabolism. Neuropeptide Y and leptin can be found between chemical substances regulating feelings of hunger and satiety. Neuropeptide Y plays the main role in the regulation of energetic homeostasis of the organism, feeding customs, sexual and reproductive functions. Concentration of neuropeptide Y increases during starvation and decreases after feeding. In anorexia nervosa the concentration of neuropeptide Y increases and, by doing that, decreases the excrection of gonadoliberines and gonadotropines. Leptin influences the feeling of hunger and its synthesis takes part, among others, in adiposal tissue. It also influences the menstruation disturbances. Rising leptin concentrations, with accompanying increasing adiposity is known to be the main factor influencing the puberty and the reverse of the malfunction of hypothalamic-pituitary-gonadal axis in malnourished persons. During hunger and low calorie intake, leptin concentration decreases, independently of adiposity. The main aim of the study was to assess concentrations of neuropeptide Y, leptin and leptin receptor in teenagers treated for anorexia nervosa. The study was conducted between 2007- 2011 in a group of 45 female teenagers with anorexia nervosa and a control group consisting of 59 healthy regularly menstruating female age peers. Concentrations of leptin, leptin receptor and neuropeptide Y (NPY) have been determined by using immunoenzymatic tests. Blood samples were obtained in fasting state. The Ethics Committee of the Medical University of Lodz approved of the study. There were statistically significant differences between mean values of BMI (14.6 vs. 19.83), median value of leptin concentration (3.79 vs. 12.09), proportions of LEP/BMI (0.1986 vs. 0.5701) in the study group when compared to controls. Higher values were found in the study group if compared to the percentage of body mass insufficiency--(23.09 vs. 3.97), neuropeptide Y concentration--(0.33 vs. 0.19), proportions of NPY/BMI--(0.023 vs. 0.0095), concentration of leptin receptor--(30.25 vs. 19.45), proportions of LR/BMI--(2.1048 vs. 0.9744). Low concentrations of leptine correlate to high concentrations of leptin receptor. A positive correlation between low body mass index and leptin receptor concentration and proportions of LR to BMI was found. A negative correlation was found between body mass loss and leptin concentration. The increasing concentration of neuropeptide Y, correlated to body mass deficency with existing high concentrations of leptin, could suggest disturbances of their regulatory axis.