title: Examination of the effect of acute levodopa administration on the loudness dependence of auditory evoked potentials (LDAEP) in humans.
abstract: BACKGROUND
  The loudness dependence of the auditory evoked potential (LDAEP) is considered a noninvasive in vivo marker of central serotonergic functioning in humans. Nevertheless, results of genetic association studies point towards a modulation of this biomarker by dopaminergic neurotransmission.
  
  
  OBJECTIVE
  We examined the effect of dopaminergic modulation on the LDAEP using L-3,4-dihydroxyphenylalanine (levodopa)/benserazide (Madopar®) as a challenge agent in healthy volunteers.
  
  
  METHODS
  A double-blind placebo-controlled challenge design was chosen. Forty-two healthy participants (21 females and 21 males) underwent two LDAEP measurements, following a baseline LDAEP measurement either placebo or levodopa (levodopa 200 mg/benserazide 50 mg) were given orally. Changes in the amplitude and dipole source activity of the N1/P2 intensities (60, 70, 80, 90, and 100 dB) were analyzed.
  
  
  RESULTS
  The participants of neither the levodopa nor the placebo group showed any significant LDAEP alterations compared to the baseline measurement. The test-retest reliability (Cronbachs Alpha) between baseline and intervention was 0.966 in the verum group and 0.759 in the placebo group, respectively.
  
  
  CONCLUSIONS
  The administration of levodopa showed no effect on the LDAEP. These findings are in line with other trials using dopamine receptor agonists.
authors: Department of General Social Psychiatry, University of Zurich, Zurich, Switzerland.
authors: K
authors: K
authors: Hitz
authors: K
authors: K
authors: Heekeren
authors: C
authors: C
authors: Obermann
authors: T
authors: T
authors: Huber
authors: G
authors: G
authors: Juckel
authors: W
authors: W
authors: Kawohl
mesh_terms: D000284:Administration, Oral; D000328:Adult; D001545:Benserazide / Q000008:administration & dosage / Q000494:pharmacology*; D015259:Dopamine Agents / Q000008:administration & dosage / Q000494:pharmacology*; D004311:Double-Blind Method; D004338:Drug Combinations; D005072:Evoked Potentials, Auditory / Q000187:drug effects*; D005260:Female; D006801:Humans; D007980:Levodopa / Q000008:administration & dosage / Q000494:pharmacology*; D008144:Loudness Perception / Q000187:drug effects*; D008297:Male; D055815:Young Adult
chemical_list: D015259:Dopamine Agents; D004338:Drug Combinations; C005177:benserazide, levodopa drug combination; D007980:Levodopa; D001545:Benserazide