On the basis of these results, the skin does not appear to contribute significantly to the levels of circulating betaE or ACTH. These data offer no support for the hypothesis that exposure to UVR leads to an increased concentration of circulating betaE, which could contribute to the feeling of well-being that often accompanies sun-bathing.

Background/Aims: A growing number of reports support evidence of proopiomelanocortin (POMC)-derived peptides in human skin cells, although not consistently. Also the effect of ultraviolet radiation (UVR) on cutaneous and plasma levels of these POMC peptides has not been established unequivocally. We hypothesized that production of b-endorphin (bE) may explain the sense of well-being many people experience when sun-bathing. The aim of the present study was to investigate whether exposure of the skin to UVR elevates plasma bE. Method: Healthy volunteers (nΩ26) received a single, weighted dose of 15 J/cm 2 of UVA. Several times during the hour following irradiation, plasma bEimmunoreactivity (bE-IR) was determined by radioimmunoassay. The effect of repeated exposure was assessed in 35 patients treated with UVB, UVA, or 256 UVA-1. Plasma ACTH-IR was monitored in parallel. Results: Overall, plasma levels of bE-IR and ACTH-IR showed no significant changes during the experiment, indicating that these peptides are not influenced by single or repeated exposures to UVR of different wavelengths. Conclusion: On the basis of these results, the skin does not appear to contribute significantly to the levels of circulating bE or ACTH. These data offer no support for the hypothesis that exposure to UVR leads to an increased concentration of circulating bE, which could contribute to the feeling of well-being that often accompanies sun-bathing.