title: Plasma levels of opioid peptides after sunbed exposures.
abstract: BACKGROUND
  Previous studies have indicated that solar and artificial ultraviolet (UV) radiation have a positive influence on psychological variables such as mood and emotional state. Circulating opioid peptides have been suggested as being important in this effect.
  
  
  OBJECTIVE
  To investigate in a controlled trial the influence of UVA radiation on opioid peptide levels.
  
  
  METHODS
  We determined plasma levels of beta-endorphin immunoreactive material (IRM) and met-enkephalin in UV-exposed (n = 35) and non-exposed (n = 9) healthy volunteers. On the first day of the study, blood samples were taken from the volunteers (time A). UVA irradiation was subsequently administered with an air-conditioned tanning device. During the UV exposures the volunteers wore opaque goggles. Twenty minutes after UV exposure, blood samples were collected again (time B). Within the following 3 weeks the volunteers had a series of five UV exposures. On the last day of the study (24 h after the sixth UV exposure) blood samples were collected (time C). The cumulative UVA doses were 96 J cm-2 for skin type II and 126 J cm-2 for skin type III. The controls had no UV exposures. Plasma beta-endorphin IRM and met-enkephalin levels were determined using radioimmunoassays.
  
  
  RESULTS
  At all times of blood collection (A, B, C), there were no significant differences in plasma levels of beta-endorphin IRM and met-enkephalin between UV-exposed and non-exposed volunteers (P > 0.05).
  
  
  CONCLUSIONS
  UVA irradiation does not significantly elevate plasma levels of beta-endorphin IRM and met-enkephalin. Therefore we suggest that psychological benefits claimed to occur after UV exposure are unlikely to be mediated by the types of circulating opioid peptides measured in this study.
authors.affiliation: Department of Dermatology, Ruhr-University Bochum, Gudrunstasse 56, D-4479 Bochum, Germany. t.gambichler@derma.de
authors.forename: T
authors.initials: T
authors.lastname: Gambichler
authors.forename: A
authors.initials: A
authors.lastname: Bader
authors.forename: M
authors.initials: M
authors.lastname: Vojvodic
authors.forename: A
authors.initials: A
authors.lastname: Avermaete
authors.forename: M
authors.initials: M
authors.lastname: Schenk
authors.forename: P
authors.initials: P
authors.lastname: Altmeyer
authors.forename: K
authors.initials: K
authors.lastname: Hoffmann
mesh_terms: D000293:Adolescent; D000328:Adult; D000339:Affect / Q000528:radiation effects; D004744:Enkephalin, Methionine / Q000097:blood; D005260:Female; D006801:Humans; D008297:Male; D018847:Opioid Peptides / Q000097:blood*; D014466:Ultraviolet Rays; D001615:beta-Endorphin / Q000097:blood
chemical_list: D018847:Opioid Peptides; D004744:Enkephalin, Methionine; D001615:beta-Endorphin