Serum Leptin and Soluble Leptin Receptor Levels in Women withAnorexia Nervosa

Overview

Background.
Leptin action in peripherial tissues is enabled by an interaction with specific transmembranereceptors. Several of leptin receptor isoforms were identified, including soluble leptin receptor isoform structurallyidentical to extracellular domain of the the long leptin receptor isoform. The soluble receptor isoform is released tothe circulation and acts probably as leptin-binding factor. The aim of our study was to measure serum concentrationsof the soluble leptin receptor in patients with anorexia nervosa and in the control group of healthy women.Relationships of soluble leptin receptor levels to body mass index (BMI), body fat content, serum leptin, TNF-aand insulin levels were also studied.Method and Results. 16 patients with anorexia nervosa and 16 age-matched lean healthy women were includedinto the study. All of the subjects were measured and weighed, the body fat content was estimated from the skinfoldthickness measurement. The blood for the determination of leptin, soluble leptin receptor and other hormonalparameters was obtained from all subjects after the overnight fasting. BMI, body fat content, serum leptin and insulinlevels in patients with anorexia nervosa were significantly lower than in the control group (BMI: 14,98 ± 2,32 vs.22,21 ± 2,48, p < 0,01, % fat content: 16,43 ± 4,56 vs. 27,19 ± 4,59, p < 0,01, leptin: 1,37 ± 1,85 ng.ml-1vs. 7,19 ±3,49 ng.ml-1, p < 0,01, insulin: 12,97 ± 2,89 mU.l-1vs. 17,09 ± 5,57 mU.l-1, p < 0,05). Serum soluble leptin receptorlevels in patients with anorexia nervosa were significantly higher compared the to control group (24,67 ± 8,3 U.ml-1vs. 15,71 ± 2,79 U.ml-1, p < 0,01). No significant differences in serum TNF-a levels between the groups studiedwere found. Serum leptin levels in both groups correlated positively with BMI and body fat content. Serum soluble leptinreceptor levels in both groups correlated negatively with BMI only. No statistically significant relationships betweenserum soluble leptin receptor levels and the rest of parameters studied were found in any of the groups studied.Conclusions. Serum soluble leptin receptors levels in patients with anorexia nervosa were signifi cantly higher incomparison with the healthy subjects. Except of the negative correlation between serum soluble leptin receptor levelsand BMI no statistically significant relationships between serum soluble leptin receptor and the rest of parametersstudied were found.

Key words:
leptin, soluble leptin receptor, anorexia nervosa, body mass index, body fat content, TNF-a.