Plasma ghrelin concentrations in narcoleptic patients
Milan Lakocevic1, Milan Petakov1, Nenad Rajsic2, Djuro Macut1, Jadranka Antic1, Vera Popovic1 & Svetozar Damjanovic1
Background: Narcolepsy is hypersomnia of central origin whose clinical features are excessive daytime sleepiness, hypnagogic hallutinations, sleep paralysis and cataplexy which comprises sudden transient loss of muscle tone often triggered by emotions. Narcolepsy with cataplexy is assiociated with hypocretin 1/orexin-A (HCRT 1/ORX-A) deficiency in central nervous system. Because of the link between ghrelin and HCRT 1/ORX-A wake-promoting effects there might be ghrelin deficiency also in narcoleptic patients with cataplexy.
Patients and methods: Plasma ghrelin concentrations have been measured in 25 narcoleptic patients (20 with and 5 without cataplexy, mean age 40.8±2.8 years) and 20 healthy age and BMI matched control subjects (mean age 41.3±3.2). Plasma ghrelin concentrations were measured by RIA (kit LINCO Research).
Results: Mean ghrelin concentrations (mean±S.E.M.) in narcoleptic patients with and without cataplexy, and healthy controls were 1123.2±77.4, 992.2±194.0 pg/ml and 1125.4±73.3 pg/ml, respectively. There was no significant difference in ghrelin levels between narcoleptic patients with and without cataplexy. Also, no difference between patients with narcolepsy and healthy controls was found. No correlation was observed between ghrelin plasma levels and clinical characteristics of narcoleptic patients (cataplexy, gender, age, BMI, duration or age of narcolepsy onset).
Conclusion: Our data show that there is no difference in plasma ghrelin concentrations in narcoleptic patients with and without cataplexy in comparison with healthy controls.