RELATION OF LEPTIN AND NEUROPEPTIDE-Y IN HUMAN BLOOD AND CEREBROSPINAL-FLUID

Leptin and neuropeptide Y (NPY) are involved in the regulation of food intake and body weight. Both hormones act through specific receptors in the central nervous system. The objective of this study was to inve stigate the relation of leptin and NPY in human plasma and cerebrospin al fluid (CSF). Leptin and NPY in CSF and in serum/plasma were measure d by radioimmunoassays in 35 patients. Leptin concentrations in serum were 100-200 fold higher than in CSF. There was a significant correlat ion between leptin levels in CSF and in serum (r=0.88, P<0.0001). Fema le patients had significantly higher leptin serum concentrations than males (16.6+/-10.9 mu g/l vs. 6.5+/-7.3 mu g/l, P=0.002). Tn contrast, NPY levels were only twofold higher in CSF than in plasma. There was no relation between leptin and NPY in CSF and serum/plasma, respective ly. The ratio of CSF and peripheral leptin levels did not correlate wi th the respective albumin ratio, indicating that leptin did not merely leak into the CSF via a defective blood-CSF barrier. It is concluded that leptin uptake from the circulation into CSF is a regulated proces s. The NPY concentration in CSF is not directly related to leptin CSF levels. (C) 1997 Elsevier Science B.V.