Reduced leptin levels in human narcolepsy

Recently, hypocretins have been implicated in the pathophysiology of narcol epsy, a sleep disorder characterized particularly by the occurrence of exce ssive daytime sleepiness and cataplexy. Hypocretins, which stimulate food i ntake, have been reported to be absent in the cerebrospinal fluid (CSF) of the majority of patients suffering from narcolepsy. Because these patients also display an increased body mass index (BMI), it has been suggested that disturbances in metabolism and food intake regulation may be present. To f urther investigate these presumed alterations, we studied the production of leptin, a fat-cell-derived hormone signaling to the brain the size of the adipose tissue. We measured the levels of leptin in serum and CSF from 15 n arcoleptic patients and compared the results to those from age-, sex- and B MI-matched control groups of depressive patients and patients suffering fro m a noninflammatory neurological disorder. Compared to both control groups, leptin levels in serum, but not in the CSF, were significantly reduced in narcoleptic patients by more than 50%. These results support the hypothesis that human narcolepsy is accompanied by complex alterations of the regulat ion of food intake and metabolism. The significance of these alterations fo r the core symptomatology of narcolepsy should be a target of future resear ch. Copyright (C) 2000 S. Karger AG, Basel.