THE EFFECT OF CHRONIC APPLICATIONS OF TRETINOIN(RETINOIC ACID) ON ACUTE RESPONSES OF MAMMALIAN SKIN TO UVB RADIATION IN VIVO |
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Authors: | J H Epstein D A Grekin |
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Institution: | Department of Dermatology, University of California, San Francisco, CA 94143, USA |
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Abstract: | Abstract The effects of long—term applications of tretinoin(retinoic acid; RA) on acute responses to UVB radiation were examined in hairless mouse skin in vivo. The skin was examined histologically and the radioactive tracer 3H]-thymidine was used to study premitotic semiconservative DNA synthesis in the epidermal basal cells. Ten and 23 wk applications of a 0.05% RA solution (3 times a wk) induced epidermal acanthosis, hypertrophy of the individual cells and an increased number of 3H]-thymidine-labelled basal cells. At both time periods there was a distinct reduction in the expected inhibition of DNA synthesis at 4 h and the expected acceleration of DNA synthesis at 48 h after a single exposure to UVB radiation. In addition, the histologic morphology was unchanged at 48 h post irradiation. Thus, the repeated RA applications had a definitive influence on at least two aspects of the cutaneous response to UVB energy. |
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