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8‐METHOXYPSORALEN INCREASES DAYTIME PLASMA MELATONIN LEVELS IN HUMANS THROUGH INHIBITION OF METABOLISM
Author(s) -
Garde E.,
Mici S.,
Knudsen K.,
Angelo H. R.,
Wulf H. C.
Publication year - 1994
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1111/j.1751-1097.1994.tb05137.x
Subject(s) - melatonin , medicine , psoralen , endocrinology , plasma concentration , stimulation , chemistry , circadian rhythm , metabolism , absorption (acoustics) , methoxsalen , in vivo , biology , biochemistry , dna , physics , microbiology and biotechnology , dermatology , acoustics , psoriasis
Abstract It is well established that in healthy humans oral intake of 5‐or 8‐methoxypsoralen (5‐and 8‐MOP) is followed by a significant increase in plasma melatonin concentrations. The effect of psoralen on rat melatonin has been studied in vitro and in vivo and a stimulation of release or secretion from the pineal gland has been suggested. In this study we examined the time‐related changes in plasma concentrations of 8‐MOP, melatonin and 6‐sulfatoxymelatonin in 15 patients admitted for routine psoralen plus UVA therapy. On the first day of treatment blood samples were collected before, and 30, 60 , 66 and 90 rnin after intake of 8‐MOP (0.6 mg/kg). Although the rate of 8‐MOP absorption vaned greatly, a significant increase ( P = 0.0002) in melatonin levels was found 60 min after 8‐MOP intake. During UVA exposure a strongly correlated decrease in mean melatonin and mean 8‐MOP concentrations was found, indicating an effect of UVA radiation, either direct or 8‐MOP mediated, on circulating melatonin levels. Plasma 6‐sulfatoxymelatonin concentrations decreased significantly between all time points, suggesting inhibition of melatonin metabolism.