The effect of topical melatonin on epidermal melanocytes in uv-irradiated black mice

ABSTRACT

Melatonin was derived from pineal gland, act as hormone and is known to be extremely active in certain biological systems. To observe the depigmentation effet of melatonin, author induced activation of melanocytes and melanin by UVB irradiation for seven days and then melatonin ointment or ointment base was applied topically on the ear skin of C57 B1 mouse. Tissue samples were obtained from 4 mice in each group before and after UVB irradiation for given days(1,3,5 and 7 week). The morphological, numerical, and ultrastructural changes of epidermal melanocytes were observed with light microscope and electron miroscope after DOPA stain. The results were as follows: 1) In all groups, the number of DOPA positive melanocytes began to decrease from 1 week. 2) The number of DOPA-positive melanocytes in melatonin ointment applied group was significantly lower than in control group. 3) In the electron microscopic findings, the number of melanosomes markedly decreased from 1 week to 7 weeks and a small amount of destructed melanosomes(vacuoles) and destroyed or swollen mitochondria in cytoplasm of th melanocyte appeared more significant in 3% melatonin ointment applied group compared to ointment base applied group from 5 weeks.