title: Simultaneous and continuous 24-hour plasma and cerebrospinal fluid leptin measurements: dissociation of concentrations in central and peripheral compartments.
abstract: The entrance of leptin into the central nervous system is of physiological relevance to the regulation of food intake, energy balance, and neuroendocrine function. To our knowledge, the relation between plasma and lumbar cerebrospinal fluid (CSF) leptin has not been examined across the 24-h period. To evaluate the relation between plasma and CSF leptin across the 24-h period, we studied simultaneous and continuous plasma and CSF leptin in nine subjects. We measured plasma and lumbar CSF leptin every 30 min for 24 h. All subjects had diurnal periodicity in 24-h plasma leptin levels, but not in CSF levels, as assessed by analysis of covariance and cosinor analysis. Plasma leptin had a significant 24-h pattern (P = 0.001), but CSF leptin did not. A 25-fold range of plasma leptin concentrations was reflected by a less-than-2-fold range in lumbar CSF leptin concentrations. Nocturnal increases in plasma leptin concentrations were not accompanied by commensurate changes in CSF values. It appears that leptin enters the brain by a mechanism that is highly saturable at physiological leptin concentrations and that the dynamics of plasma leptin is not accompanied by similar dynamics in CSF leptin measured at the lumbar spinal level. Therefore, it is not possible to use plasma leptin levels to predict lumbar CSF leptin concentrations. Although we acknowledge that lumbar CSF concentrations do not fully reflect the dynamics of leptin in the brain, we suggest that the nocturnal saturability of leptin transport into the central nervous system might help explain the lack of responsiveness to the central physiologic effects of leptin in states of hyperleptinemia, such as obesity.
authors.affiliation: Center for Pharmacogenomics and Interdepartmental Clinical Pharmacology Center, Neuropsychiatric Institute and David Geffen School of Medicine at University of California, Los Angeles, Los Angeles, California 90095, USA.
authors.forename: Ma-Li
authors.initials: ML
authors.lastname: Wong
authors.forename: Julio
authors.initials: J
authors.lastname: Licinio
authors.forename: Bulent O
authors.initials: BO
authors.lastname: Yildiz
authors.forename: Christos S
authors.initials: CS
authors.lastname: Mantzoros
authors.forename: Paolo
authors.initials: P
authors.lastname: Prolo
authors.forename: Mitchel
authors.initials: M
authors.lastname: Kling
authors.forename: Philip W
authors.initials: PW
authors.lastname: Gold
mesh_terms: D000328:Adult; D001692:Biological Transport; D015992:Body Mass Index; D001921:Brain / Q000378:metabolism; D002940:Circadian Rhythm; D005260:Female; D006801:Humans; D020738:Leptin / Q000097:blood* / Q000134:cerebrospinal fluid*; D008297:Male; D008875:Middle Aged; D012016:Reference Values
chemical_list: D020738:Leptin