title: Circadian rhythm of CSF monoamines and hypocretin-1 in restless legs syndrome and Parkinson's disease.
abstract: The symptoms of restless legs syndrome (RLS) have a circadian pattern and central nervous system dopamine has been implicated in the pathogenesis of the condition. We sought to characterize circadian variation in dopamine and related compounds in human cerebro-spinal fluid (CSF). CSF was continuously withdrawn for 22 h from an implanted lumbar intradural catheter and sampled from three patients with RLS, three patients with Parkinson's disease (PD) and three healthy volunteers. Patients had moderate disease severity and took no medications. We assayed CSF dopamine (DA), homovanillic acid (HVA), dihydroxy-phenylacetic acid (DOPAC) and 5-hydroxyindole acetic acid (5-HIAA) from samples every 30 min by reversed-phase HPLC coupled with electrochemical detection. We also measured CSF levels of hypocretin-1 every hour by RIA. The procedure was well-tolerated. One patient ended the study early due to lumbar radicular pain and was not included in the analysis. There were no changes in CSF cell counts or protein levels from the first to the last samples. There was no difference in any of the compounds between groups, so we fit 24-h cosines to examine if the entire group had significant phase consistency. There was a peak for dopamine at 10 a.m. (p<0.025) and for HVA at 2 p.m. (p<0.01), but no evidence of a significant 24-h rhythm for DOPAC, 5-HIAA, the HVA/5-HIAA ratio, or hypocretin-1. These results demonstrate a circadian rhythm for CSF dopamine and HVA concentrations in humans, with higher levels in the daytime than at nighttime. This circadian variation could underlie the symptoms of RLS and sleep-related variation in motor function in PD.
authors.affiliation: Scripps Clinic Division of Neurology and Scripps Clinic Sleep Center, The Scripps Research Institute, Molecular and Integrative Neurosciences Department, La Jolla, CA, USA. jpoceta@scripps.edu
authors.forename: J Steven
authors.initials: JS
authors.lastname: Poceta
authors.forename: Loren
authors.initials: L
authors.lastname: Parsons
authors.forename: Scott
authors.initials: S
authors.lastname: Engelland
authors.forename: Daniel F
authors.initials: DF
authors.lastname: Kripke
mesh_terms: D015102:3,4-Dihydroxyphenylacetic Acid / Q000134:cerebrospinal fluid; D000368:Aged; D015306:Biogenic Monoamines / Q000134:cerebrospinal fluid*; D002851:Chromatography, High Pressure Liquid; D002940:Circadian Rhythm; D004298:Dopamine / Q000134:cerebrospinal fluid; D005240:Feasibility Studies; D005260:Female; D006719:Homovanillic Acid / Q000134:cerebrospinal fluid; D006801:Humans; D006897:Hydroxyindoleacetic Acid / Q000134:cerebrospinal fluid; D047908:Intracellular Signaling Peptides and Proteins / Q000134:cerebrospinal fluid*; D008297:Male; D008875:Middle Aged; D009479:Neuropeptides / Q000134:cerebrospinal fluid*; D000068797:Orexins; D010300:Parkinson Disease / Q000134:cerebrospinal fluid* / Q000503:physiopathology; D010865:Pilot Projects; D012148:Restless Legs Syndrome / Q000134:cerebrospinal fluid* / Q000503:physiopathology
chemical_list: D015306:Biogenic Monoamines; C000596229:HCRT protein, human; D047908:Intracellular Signaling Peptides and Proteins; D009479:Neuropeptides; D000068797:Orexins; D015102:3,4-Dihydroxyphenylacetic Acid; D006897:Hydroxyindoleacetic Acid; D004298:Dopamine; D006719:Homovanillic Acid