Effects of narrow band ultraviolet B at therapeutic doses on the proliferation of, apoptosis in and melanocortin-1 receptor (MC-1R) expression by melanocytes

Abstract

Objective To investigate the mechanism of repigmentation in vitiligo induced by narrow band ultraviolet B (NB-UVB) via observing the effects of 311 nm NB-UVB on the proliferation of, apoptosis and melanogenesis in melanocytes. Methods Immortalized B10BR melanocytes were irradiated with NB-UVB at varying doses (400, 800 and 1200 mJ/cm2). Subsequently, the proliferation of and apoptosis in melanocytes were detected by MTT assay and flow cytometry, respectively, and the content of melanin was determined by NaOH assay. The expression of BCL-2 mRNA was examined by RT-PCR, and MC-1R expression of melanoeytes by immunocytochemistry and Western blotting. Results The proliferation of and apoptosis in melanocytes experienced no obvious change after irradiation with NB-UVB at the three tested doses. In B10BR melanocytes irradiated with NB-UVB at 400, 800 and 1200 mJ/cm2, the melanin content was 1.42, 1.78, 2.05 times, the mRNA expression of BCL-2 was 1.75, 2.32, 3.28 times, and the protein expression of MC-1R was 1.68, 2.35 and 3.01 times, that in unirradiated melanocytes, respectively. Conclusion NB-UVB irradiation at therapeutic doses could promote the melanogenesis in, enhance anti-oxidative stress activities of melanocytes,by upregulating the expressions of BCL-2 and MC-1R, with no marked effects on the apoptosis in melanocytes. Key words: Melanocytes; Ultraviolet rays; Apoptosis; Receptor,melanocortin,type 1; Vitiligo