Plasma levels of opioid peptides after sunbed exposures
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.
Objectives To investigate in a controlled trial the influence of UVA radiation on opioid peptide levels.
Methods We determined plasma levels of β-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 β-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 β-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 β-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.
Document Type: Research Article
Affiliations: 1: Department of Dermatology, Ruhr-University Bochum, Gudrunstasse 56, D-4479 Bochum, Germany 2: Department of Anaesthesiology and Intensive Care Medicine, Charité University Hospital, Schumannstrasse 20–21, D-10017 Berlin, Germany
Publication date: December 1, 2002