title: Circadian effects of dopaminergic treatment in restless legs syndrome.
abstract: OBJECTIVE
  Although an essential diagnostic feature of restless legs syndrome (RLS) is the presence of circadian symptom variations, with an increase in the evening or at night, the mechanisms underlying this time-bound variation remain unknown. Since dopaminergic mechanisms seem to play a central role in the pathophysiology of RLS, it is likely that circadian variations in the dopaminergic system or factors affecting it cause the nightly increase. The reverse is also possible; dopaminergic medication might affect melatonin function, a key element of the circadian system. The present study investigated the effects of dopaminergic medication on melatonin secretion in RLS.
  
  
  METHODS
  Eight previously untreated patients diagnosed with idiopathic RLS underwent a three-week, open-labeled treatment with 400 mg L-DOPA (+100 mg CarbiDOPA). Dim Light Melatonin Onset (DLMO), a marker of circadian phase, was determined before and after treatment.
  
  
  RESULTS
  Compared to baseline, earlier DLMO was found in L-DOPA treated patients (21:00+/-1:20 vs. 18:50+/-0:55; P < 0.05). Anticipation of DLMO was more marked in the subgroup of patients showing augmentation. A positive correlation was observed between change of DLMO, sleep latency and time of onset of symptoms following treatment with L-DOPA.
  
  
  CONCLUSIONS
  Our results suggest that L-DOPA may exert chronobiotic effects in RLS.
authors.affiliation: Sleep Disorders Unit, Department of Neurology, Fundación Jiménez Díaz, Universidad Autónoma de Madrid, Avda. Reyes Católicos 2, 28040 Madrid, Spain. d.garciaborreguero@fjd.es
authors.forename: Diego
authors.initials: D
authors.lastname: Garcia-Borreguero
authors.forename: Carolina
authors.initials: C
authors.lastname: Serrano
authors.forename: Oscar
authors.initials: O
authors.lastname: Larrosa
authors.forename: Juan José
authors.initials: JJ
authors.lastname: Granizo
mesh_terms: D000328:Adult; D002940:Circadian Rhythm / Q000187:drug effects* / Q000502:physiology*; D015259:Dopamine Agents / Q000494:pharmacology*; D005260:Female; D006801:Humans; D007980:Levodopa / Q000494:pharmacology*; D008029:Lighting; D008297:Male; D008550:Melatonin / Q000378:metabolism*; D008875:Middle Aged; D017286:Polysomnography; D012148:Restless Legs Syndrome / Q000378:metabolism*; D012463:Saliva / Q000378:metabolism; D013997:Time Factors
chemical_list: D015259:Dopamine Agents; D007980:Levodopa; D008550:Melatonin