Leptin in cerebrospinal fluid from children: Correlation with plasma leptin, sexual dimorphism, and lack of protein binding

Background: Previous studies in adults have established that leptin is pres ent at very low concentrations in cerebrospinal fluid (CSF), but few data e xist concerning CSF leptin in children. Current evidence suggests that CSF leptin concentrations interact with hypothalamic centers controlling food i ntake. Serum leptin concentrations manifest a sexual dimorphism that arises during puberty. Methods: Leptin concentrations were determined in CSF from 42 pre- and post pubertal children who had been objectively classified into non-neurological disease or aseptic meningitis groups. Multivariate analysis of the depende nce of CSF leptin on gender, pubertal state, body mass index (BMI), presenc e of aseptic meningitis, and CSF protein concentration was performed. Results: CSF leptin concentrations correlated with log-transformed plasma l eptin concentrations in concomitantly collected samples (r = 0.582; P = 0.0 29). BMI and gender were significant determinants of CSF leptin in postpube rtal children, but only BMT was significant in prepubertal children. Analys is with HPLC to separate protein-bound and free forms of leptin found only free leptin in CSF. Conclusions: CSF leptin concentrations in children reflect plasma leptin co ncentrations, including the advent of sexual dimorphism at puberty. Only fr ee leptin is detectable in CSF, suggesting that it is the biologically acti ve form. (C) 2000 American Association for Clinical Chemistry.