Prospective evaluation of leptin and neuropeptide Y (NPY) serum levels in girls with anorexia nervosa.

OBJECTIVES: The pathogenesis of anorexia nervosa (AN) remains still unclear. It has been reported that neuropeptides may play a role in the control of appetite and hormone release contributing to hormonal disturbances in AN. However the question if neuropeptide alterations are consequence or cause of malnutrition is still unresolved.

METHODS: Serum leptin, neuropeptide Y (NPY) concentrations as well as hormones (FSH, LH, estradiol, cortisol and fT4) serum levels were prospectively estimated in 19 girls aged 11.7-17.7 years (mean 15.5 years) with anorexia nervosa (AN) at the admission to the hospital (baseline) and at follow-up after 7.21+ 2.32 months of treatment. The treatment consisted of hypercaloric diet, psychotherapy and vitamins supplementation.

RESULTS: Mean leptin concentration significantly increased from 7.99 + 2.6 to 9.98 + 2.48 microg/ml (p<0.01), whereas mean NPY concentration significantly decreased from 34.10 + 9.81 to 29.6 + 8.04 pmol/l (p<0.01). Leptin/BMI ratio was constant, while NPY/BMI ratio decreased. There were no significant differences between leptin and NPY serum concentrations at baseline and follow-up in eumenorrheic vs. amenorrheic patients. Simple linear correlation analysis showed negative correlation between leptin and NPY concentrations at baseline (r=-0.67; p<0.05) and at follow-up (r=-0.76; p<0.05) only in eumenorrheic subgroup. There were no significant correlations between leptin, NPY and BMI and body weight values.

CONCLUSIONS: 1) Serum concentration of leptin increases and serum concentration of NPY decreases significantly during the treatment of anorectic girls. 2) These changes do not correspond with increasing body weight and BMI suggesting disregulation of appetite and body weight control mechanisms in AN. 3) Altered neuroregulation of the neuropeptides (leptin and NPY) secretion may contribute persistent amenorrhea after weight gain in anorectic patients with low initial BMI.