The effect of azelaic acid and retinoic acid on epidermal melanocytes in UVB-irradiated black mice

Han, Kyung Won; Lee, Ki Hong; Myung, Ki Bum

Abstract

Increased melanin pigmentation following ultraviolet irradiat.ion is due to increasing tyrosinase activity and multiplicatian of functioning melanocytes. After UV-irradiation, the size of melanocytes increases, and melanocyte dendrites elongatc, and branch. In this experiment, we induced the activation of melanocyts in the epidermis of C57BL black mice by ultraviolet-B(UVB) irradiation and observcd ihe effect of azelaic acid and retinoic acid on the UVB activated epidermal melanocytes. Sixty C57BL black mice were irradiated by UVB 100mJ/cm daily for 10 days, and then azeiaic acid and retinoic acid were topically applied daily for 7 weeks. For the estimation of morphologic change of epidermal melanocytes, light microscopic observation with split DOPA stain was performed at the end of the 1st, 3rd, 5th and 7th week of topical application. The results are summerized as follows : 1. The number, size and circumference of DOPA-positive epidermal melanocytes were significantly decreased in 20% azelaic acid applied group and 30% azelaic acid and 0.05% retinoic acid applied group. 2. In 20% azelaic;i.cid and 0.05% retinoic acid applied group, the number, size and circumference of DOPA-positive epidermal melanocytes were nore significantly decreased than in 20% azelaic acid applied group. In summary, the present study suggets that azelaic acid act as a depigmenting agent on epidermal melanocyte; and such depigmenting effect of azelaic acid was increased by addition of retinoic acid.