en Radiation Biology Radiation Biology تحقيق بديع Original Research <div style="text-align: justify;">Background: We investigated whether topical administration of melatonin ameliorates radiation-induced skin fibrosis (RISF) and inhibits the expression of profibrogenic genes in mice. Materials and Methods: Forty-eight female BALB/c mice were randomly divided into three groups: topically applied 5% ethanol (Control), topically applied 5% ethanol plus irradiation (IR), and topically applied melatonin plus irradiation (Mel+IR). The right hind legs of the IR and Mel+IR group mice were exposed to two fractions of electron beam radiation (20 Gy &times; 2). For 4 weeks, melatonin solution (10 mg/day) was topically applied to Mel+IR group mice. Fourteen days after IR, the relative levels of transforming growth factor (TGF)-&beta;1 mRNA expression and TGF-&beta;1 protein in skin specimens were analyzed by real-time quantitative PCR and immunohistochemical staining. Dermal thickness and tissue collagen accumulation were measured at 100 days post irradiation. Results: The Radiation caused a 2.2-fold increase in TGF-&beta;1 mRNA expression relative to that in control group, which was decreased by 37% following melatonin treatment (P = 0.024). We also observed substantial reduction of TGF-&beta;1 expression in immunohistochemical studies. The mean values of dermal thickness were 105 &plusmn; 11 &mu;m (Control), 195 &plusmn; 21 &mu;m (IR), and 148 &plusmn; 19 &mu;m (Mel+IR). Dermal thickness and collagen accumulation, which increased in the IR group, was significantly reduced by topically applied melatonin.&nbsp; Conclusion: Topical administration of melatonin successfully attenuated RISF.</div> Melatonin, Radiation, Fibrosis, Transforming growth factor-β, Topical application. 617 624 http://ijrr.com/browse.php?a_code=A-10-1-824&slc_lang=en&sid=1 D.H. Kim 7900319475328460014009 7900319475328460014009 No Department of Radiation Oncology, Otorhinolaryngology, and Hemato-oncology, Biomedical Research Institute, Pusan National University Hospital and Pusan National University School of Medicine, Pusan National University, Busan, Korea Y.M. Choi 7900319475328460014010 7900319475328460014010 No Department of Radiation Oncology, DongA University Hospital, Busan, Korea Y.K. Ki 7900319475328460014011 7900319475328460014011 No Department of Radiation Oncology, Pusan National University Yangsan Hospital and Pusan National University School of Medicine, Yangsan, Korea K.S. Cho 7900319475328460014012 7900319475328460014012 No Department of Radiation Oncology, Otorhinolaryngology, and Hemato-oncology, Biomedical Research Institute, Pusan National University Hospital and Pusan National University School of Medicine, Pusan National University, Busan, Korea Y.J. Choi 7900319475328460014013 7900319475328460014013 No Department of Radiation Oncology, Otorhinolaryngology, and Hemato-oncology, Biomedical Research Institute, Pusan National University Hospital and Pusan National University School of Medicine, Pusan National University, Busan, Korea W.T. Kim rokwt@hanmail.net 7900319475328460014014 7900319475328460014014 Yes Department of Radiation Oncology, Otorhinolaryngology, and Hemato-oncology, Biomedical Research Institute, Pusan National University Hospital and Pusan National University School of Medicine, Pusan National University, Busan, Korea