title: Normal Morning Melanin-Concentrating Hormone Levels and No Association with Rapid Eye Movement or Non-Rapid Eye Movement Sleep Parameters in Narcolepsy Type 1 and Type 2.
abstract: OBJECTIVE
  Other than hypocretin-1 (HCRT-1) deficiency in narcolepsy type 1 (NT1), the neurochemical imbalance of NT1 and narcolepsy type 2 (NT2) with normal HCRT-1 levels is largely unknown. The neuropeptide melanin-concentrating hormone (MCH) is mainly secreted during sleep and is involved in rapid eye movement (REM) and non-rapid eye movement (NREM) sleep regulation. Hypocretin neurons reciprocally interact with MCH neurons. We hypothesized that altered MCH secretion contributes to the symptoms and sleep abnormalities of narcolepsy and that this is reflected in morning cerebrospinal fluid (CSF) MCH levels, in contrast to previously reported normal evening/afternoon levels.
  
  
  METHODS
  Lumbar CSF and plasma were collected from 07:00 to 10:00 from 57 patients with narcolepsy (subtypes: 47 NT1; 10 NT2) diagnosed according to International Classification of Sleep Disorders, Third Edition (ICSD-3) and 20 healthy controls. HCRT-1 and MCH levels were quantified by radioimmunoassay and correlated with clinical symptoms, polysomnography (PSG), and Multiple Sleep Latency Test (MSLT) parameters.
  
  
  RESULTS
  CSF and plasma MCH levels were not significantly different between narcolepsy patients regardless of ICSD-3 subtype, HCRT-1 levels, or compared to controls. CSF MCH and HCRT-1 levels were not significantly correlated. Multivariate regression models of CSF MCH levels, age, sex, and body mass index predicting clinical, PSG, and MSLT parameters did not reveal any significant associations to CSF MCH levels.
  
  
  CONCLUSIONS
  Our study shows that MCH levels in CSF collected in the morning are normal in narcolepsy and not associated with the clinical symptoms, REM sleep abnormalities, nor number of muscle movements during REM or NREM sleep of the patients. We conclude that morning lumbar CSF MCH measurement is not an informative diagnostic marker for narcolepsy.
authors.affiliation: Molecular Sleep Laboratory, Department of Clinical Biochemistry, Rigshospitalet, Glostrup, Denmark.|FU-Berlin, Faculty Biology, Chemistry, Pharmacy, Takustr, Berlin, Germany.
authors.forename: Maren
authors.initials: M
authors.lastname: Schrölkamp
authors.affiliation: Danish Center for Sleep Medicine, University of Copenhagen, Rigshospitalet, Glostrup, Denmark.
authors.forename: Poul J
authors.initials: PJ
authors.lastname: Jennum
authors.affiliation: Molecular Sleep Laboratory, Department of Clinical Biochemistry, Rigshospitalet, Glostrup, Denmark.
authors.forename: Steen
authors.initials: S
authors.lastname: Gammeltoft
authors.affiliation: Molecular Sleep Laboratory, Department of Clinical Biochemistry, Rigshospitalet, Glostrup, Denmark.
authors.forename: Anja
authors.initials: A
authors.lastname: Holm
authors.affiliation: Molecular Sleep Laboratory, Department of Clinical Biochemistry, Rigshospitalet, Glostrup, Denmark.
authors.forename: Birgitte R
authors.initials: BR
authors.lastname: Kornum
authors.affiliation: Danish Center for Sleep Medicine, University of Copenhagen, Rigshospitalet, Glostrup, Denmark.|Norwegian Centre of Expertise for Neurodevelopmental Disorders and Hypersomnias (NevSom), Oslo University Hospital, Ullevål, Norway.
authors.forename: Stine
authors.initials: S
authors.lastname: Knudsen
mesh_terms: D000328:Adult; D003718:Denmark; D005260:Female; D006801:Humans; D007028:Hypothalamic Hormones / Q000097:blood* / Q000134:cerebrospinal fluid*; D008297:Male; D008543:Melanins / Q000097:blood* / Q000134:cerebrospinal fluid*; D009290:Narcolepsy / Q000097:blood* / Q000134:cerebrospinal fluid*; D010907:Pituitary Hormones / Q000097:blood* / Q000134:cerebrospinal fluid*; D017286:Polysomnography; D012890:Sleep / Q000502:physiology*; D012895:Sleep, REM / Q000502:physiology
chemical_list: D007028:Hypothalamic Hormones; D008543:Melanins; D010907:Pituitary Hormones; C019463:melanin-concentrating hormone
keywords: biomarker; cerebrospinal fluid; melanin-concentrating hormone; narcolepsy; plasma