caa a22 4500 47577227X CHVBK 20180406123620.0 cr unu---uuuuu 170329e20000401xx s 000 0 eng 10.1007/s001250051326 doi (NATIONALLICENCE)springer-10.1007/s001250051326 Free and protein bound leptin are distinct and independently controlled factors in energy regulation [Elektronische Daten] [G. Brabant, R. Horn, A. von zur Mühlen, B. Mayr, U. Wurster, F. Heidenreich, D. Schnabel, A. Grüters-Kieslich, T. Zimmermann-Belsing, U. Feldt-Rasmussen] Aims/hypothesis. Leptin exerts important regulating effects on energy homeostasis and could have a central role in our understanding of obesity, diabetes mellitus and the metabolic syndrome. Leptin circulates in a free and protein bound form. The aim of the present study was to test whether both fractions of the leptin system can be selectively regulated and thus serve independent physiological roles.¶Methods. Using specific radioimmunoassays we measured both leptin components in relation to BMI in healthy subjects before and after weight reduction and in hyperthyroid patients during correction of thyrotoxicosis. In the latter group body composition and resting energy expenditure was monitored. In addition, we measured serum and cerebrospinal fluid concentrations of free and bound leptin in patients with neurological disorders.¶Results. Under all conditions free leptin concentrations reflected body fat mass. Bound leptin concentrations decreased during weight reduction but also after treatment of hyperthyroidism despite an increase in fat mass. Direct measurement of resting energy expenditure and bound leptin in hyperthyroid patients and under thyrostatic treatment showed a significant positive correlation of both variables. In contrast to free leptin whose transport into the cerebrospinal fluid appears to be saturated at low physiological concentrations of serum free leptin, bound leptin concentrations in the cerebrospinal fluid increased in parallel to serum concentrations over the whole physiologically relevant range.¶Conclusion/interpretation. Our data indicate a distinct role of free and bound leptin in the feedback regulating energy intake and expenditure and could have important implications for our understanding of the physiology and pathophysiology of leptin-dependent signalling. [Diabetologia (2000) 43: 438-442] Springer-Verlag Berlin Heidelberg, 2000 Keywords Free leptin, bound leptin, resting energy expenditure, hyperthyroidism, weight reduction, leptin in CSF nationallicence Brabant G. Department of Clinical Endocrinology, School of Medicine, Hannover, Germany, DE aut Horn R. Department of Clinical Endocrinology, School of Medicine, Hannover, Germany, DE aut von zur Mühlen A. Department of Clinical Endocrinology, School of Medicine, Hannover, Germany, DE aut Mayr B. Department of Clinical Endocrinology, School of Medicine, Hannover, Germany, DE aut Wurster U. Department of Neurology and Clinical Neurophysiology, School of Medicine, Hannover, Germany, DE aut Heidenreich F. Department of Neurology and Clinical Neurophysiology, School of Medicine, Hannover, Germany, DE aut Schnabel D. Children's Hospital, Charité Campus Virchow, Berlin, Germany, DE aut Grüters-Kieslich A. Children's Hospital, Charité Campus Virchow, Berlin, Germany, DE aut Zimmermann-Belsing T. University Hospital, Rigs Hospital, Copenhagen, Denmark, DK aut Feldt-Rasmussen U. University Hospital, Rigs Hospital, Copenhagen, Denmark, DK aut https://doi.org/10.1007/s001250051326 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s001250051326 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Brabant G. Department of Clinical Endocrinology, School of Medicine, Hannover, Germany, DE aut NATIONALLICENCE 700 1- Horn R. Department of Clinical Endocrinology, School of Medicine, Hannover, Germany, DE aut NATIONALLICENCE 700 1- von zur Mühlen A. Department of Clinical Endocrinology, School of Medicine, Hannover, Germany, DE aut NATIONALLICENCE 700 1- Mayr B. Department of Clinical Endocrinology, School of Medicine, Hannover, Germany, DE aut NATIONALLICENCE 700 1- Wurster U. Department of Neurology and Clinical Neurophysiology, School of Medicine, Hannover, Germany, DE aut NATIONALLICENCE 700 1- Heidenreich F. Department of Neurology and Clinical Neurophysiology, School of Medicine, Hannover, Germany, DE aut NATIONALLICENCE 700 1- Schnabel D. Children's Hospital, Charité Campus Virchow, Berlin, Germany, DE aut NATIONALLICENCE 700 1- Grüters-Kieslich A. Children's Hospital, Charité Campus Virchow, Berlin, Germany, DE aut NATIONALLICENCE 700 1- Zimmermann-Belsing T. University Hospital, Rigs Hospital, Copenhagen, Denmark, DK aut NATIONALLICENCE 700 1- Feldt-Rasmussen U. University Hospital, Rigs Hospital, Copenhagen, Denmark, DK aut Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer