title: Hypocretin (orexin) loss in Parkinson's disease.
abstract: The hypothalamic hypocretin (orexin) system plays a central role in the regulation of various functions, including sleep/wake regulation and metabolism. There is a growing interest in hypocretin function in Parkinson's disease (PD), given the high prevalence of non-motor symptoms such as sleep disturbances in this disorder. However, studies measuring CSF hypocretin levels have yielded contradictory results. In PD patients and matched controls, we (i) estimated the number of hypocretin neurons in post-mortem hypothalami using immunocytochemistry and an image analysis system (ii) quantified hypocretin levels in post-mortem ventricular CSF and (iii) prefrontal cortex using a radioimmunoassay. Furthermore, presence of Lewy bodies was verified in the hypothalamic hypocretin cell area. Data are presented as median (25th-75th percentile). We showed a significant decrease between PD patients and controls in (i) the number of hypocretin neurons (PD: 20 276 (13 821-31 229); controls: 36 842 (32 546-50 938); P = 0.016); (ii) the hypocretin-1 concentration in post-mortem ventricular CSF (PD: 365.5 pg/ml (328.0-448.3); controls: 483.5 (433.5-512.3); P = 0.012) and (iii) the hypocretin-1 concentrations in prefrontal cortex (PD: 389.6 pg/g (249.2-652.2); controls: 676.6 (467.5-883.9); P = 0.043). Hypocretin neurotransmission is affected in PD. The hypocretin-1 concentration in the prefrontal cortex was almost 40% lower in PD patients, while ventricular CSF levels were almost 25% reduced. The total number of hypocretin neurons was almost half compared to controls.
authors.affiliation: Department of Neurology, Leiden University Medical Center, Leiden, The Netherlands.
authors.forename: Rolf
authors.initials: R
authors.lastname: Fronczek
authors.forename: Sebastiaan
authors.initials: S
authors.lastname: Overeem
authors.forename: Sandy Y Y
authors.initials: SY
authors.lastname: Lee
authors.forename: Ingrid M
authors.initials: IM
authors.lastname: Hegeman
authors.forename: Johannes
authors.initials: J
authors.lastname: van Pelt
authors.forename: Sjoerd G
authors.initials: SG
authors.lastname: van Duinen
authors.forename: Gert Jan
authors.initials: GJ
authors.lastname: Lammers
authors.forename: Dick F
authors.initials: DF
authors.lastname: Swaab
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D002452:Cell Count; D005260:Female; D006801:Humans; D007031:Hypothalamus / Q000737:chemistry / Q000473:pathology; D007124:Immunoenzyme Techniques; D047908:Intracellular Signaling Peptides and Proteins / Q000032:analysis* / Q000134:cerebrospinal fluid / Q000172:deficiency; D016631:Lewy Bodies / Q000737:chemistry; D008297:Male; D008875:Middle Aged; D009474:Neurons / Q000737:chemistry; D009479:Neuropeptides / Q000032:analysis* / Q000134:cerebrospinal fluid / Q000172:deficiency; D000068797:Orexins; D010300:Parkinson Disease / Q000378:metabolism* / Q000473:pathology; D017397:Prefrontal Cortex / Q000737:chemistry
chemical_list: C000596229:HCRT protein, human; D047908:Intracellular Signaling Peptides and Proteins; D009479:Neuropeptides; D000068797:Orexins