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Chronic UVA (365‐nm) irradiation induced scratching in hairless mice: dose‐time dependency and the effect of ketanserin
Author(s) -
Laat J. M. T.,
Seité S.,
Groenendijk M.,
Vloten W A.,
Gruijl F. R.
Publication year - 1997
Publication title -
experimental dermatology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.108
H-Index - 96
eISSN - 1600-0625
pISSN - 0906-6705
DOI - 10.1111/j.1600-0625.1997.tb00175.x
Subject(s) - hairless , scratching , histamine , ketanserin , chemistry , pharmacology , medicine , serotonin , 5 ht receptor , receptor , biochemistry , physics , acoustics
In a study on the dose–response relationship for longwave UVA (UVAI; 340–400 nm) carcinogenesis in hairless mice scratch marks appeared after months of daily exposure as an unwanted side effect. Tumor induction in the highest of the 4 tested dose groups (receiving a daily dose of 430 kJ/m 2 of 365‐nm radiation) could not be determined because extensive scarification occurred prior to the development of any tumors. The induction of scratch marks could be scored and quantified in all 4 dose groups tested. The UVA I dose‐dependencies for the induction of tumors and scratch marks were compared. We found that the induction of scratch marks depended mainly on the cumulative UVA1 exposure, whereas tumor induction showed a lesser dose‐dependency. An attempt was made to prevent the apparent pruritogenic effect of UVA1 irradiation and to understand its mechanism. The influence of ketanserin, a serotonin/histamine antagonist, on the UVA1 induction of scratch marks was tested in groups of 8 mice daily irradiated with 430 kJ/m 2 . No difference was found between treated and untreated animals. Histological examination of skin biopsies from irradiated mice from the 430‐kJ/m 2 dose group from the UVA1 careinogenic experiment, showed no changes in numbers of mast cells or other inflammatory features when compared to skin biopsies from unirradiated control mice. This indicated that UVA1‐induced scratching is not mediated through mast cell release of scrotonin and/or histamine. An adequate therapeutic treatment which can prevent UVA1‐induccd scratching would enable us to lest tumor induction with UVA1 over a larger close range, and may provide additional insight in how this radiation damages the skin. It remains conjectural whether there exists an analogous UVA‐induccd pruritus in human skin.