title: Higher Orexin A levels in lumbar compared to ventricular CSF: a study in idiopathic normal pressure hydrocephalus.
abstract: Orexin A (ORX-A) is implicated in the regulation of various physiological processes, including sleep/wake cycles and reward/motivation. The hypothalamic ORX-A neurons project throughout the brain and spinal cord. In the present study we established and compared ORX-A levels in lumbar and ventricular cerebrospinal fluid (CSF) samples, drawn from idiopathic normal pressure hydrocephalus (INPH) patients, during respectively, lumbar puncture and shunt placement. Ventricular and lumbar CSF levels of total protein and of the dopamine, serotonin and norepinephrine metabolites HVA, 5-HIAA and MHPG respectively, were also estimated. ORX-A was quantified using a commercially available radioimmunoassay kit. Neurotransmitter metabolites were quantified by high performance liquid chromatography. Expectedly, HVA and 5-HIAA levels were significantly higher and total protein levels lower in ventricular compared to lumbar CSF while there were no differences in MHPG levels. However, in contrast to HVA and 5-HIAA and similar to total protein, lumbar ORX-A levels were significantly higher than ventricular levels. The higher lumbar compared to ventricular ORX-A levels may reflect elevated contributions from the spinal cord. The finding of a ventriculo-lumbar difference for ORX-A should be considered in studies utilizing its CSF levels in assessing Orexin system status.
authors.affiliation: Department of Neurosurgery, Athens University Medical School, Athens, Greece; Hellenic Centre for Neurosurgery Research "Professor Petros S. Kokkalis", Athens, Greece. Electronic address: theodosis.kalamatianos@kcl.ac.uk.
authors.forename: T
authors.initials: T
authors.lastname: Kalamatianos
authors.affiliation: Department of Neurology, Eginition Hospital, Athens University Medical School, Athens, Greece.
authors.forename: M
authors.initials: M
authors.lastname: Markianos
authors.affiliation: Department of Neurosurgery, Athens University Medical School, Athens, Greece.
authors.forename: K
authors.initials: K
authors.lastname: Margetis
authors.affiliation: Hellenic Centre for Neurosurgery Research "Professor Petros S. Kokkalis", Athens, Greece.
authors.forename: F
authors.initials: F
authors.lastname: Bourlogiannis
authors.affiliation: Department of Neurosurgery, Athens University Medical School, Athens, Greece; Hellenic Centre for Neurosurgery Research "Professor Petros S. Kokkalis", Athens, Greece.
authors.forename: G
authors.initials: G
authors.lastname: Stranjalis
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D002552:Cerebral Ventricles / Q000378:metabolism*; D005260:Female; D006801:Humans; D006850:Hydrocephalus, Normal Pressure / Q000134:cerebrospinal fluid*; D047908:Intracellular Signaling Peptides and Proteins / Q000134:cerebrospinal fluid*; D008161:Lumbosacral Region; D008297:Male; D008875:Middle Aged; D009479:Neuropeptides / Q000134:cerebrospinal fluid*; D000068797:Orexins; D013129:Spinal Puncture
chemical_list: C000596229:HCRT protein, human; D047908:Intracellular Signaling Peptides and Proteins; D009479:Neuropeptides; D000068797:Orexins
keywords: Cerebrospinal fluid; Hydrocephalus; Orexin-A; Ventriculo-lumbar