The effect of melatonin on melanocyte functions was studied by incubating whole-skin organ cultures with melatonin, as well as by assessing melatonin positivity in melanocytes versus dendricity and pigmentation, when arrested in the G2 phase. From this study, it was observed that melatonin positivity is inversely related to the length of UV exposure. Increasing melatonin levels are related to decreasing dendricity and pigment donation during photoresponse in the G2 phase. Melanocyte melatonin positivity increases with dark incubation and is higher with a pulse of UV exposure after dark incubation with melatonin. This increase is associated with a doubling of melanocyte number after dark incubation and a further doubling upon exposure to a pulse of UV. The melanocytes directly take up melatonin, which results in a marked increase in their numbers. Thus, extreme caution should be exercised when using melatonin as an anticancer drug. This finding also simulates the melanocyte repopulation of the skin with repigmentation during summer in polar animals.
Dr. Bhanu Iyengar
Pigment Cell Centre, Iyengar Farm
New Delhi 110037 (India)
Number of Print Pages : 7
Number of Figures : 6, Number of Tables : 0, Number of References : 17
Biological Signals and Receptors
Vol. 9, No. 5, Year 2000 (Cover Date: September-October 2000)
Journal Editor: S.F. Pang, Hong Kong; P.A. Ward, Ann Arbor, Mich.; D.P. Cardinali, Buenos Aires
ISSN: 1422–4933 (print), 1422–4992 (Online)
For additional information: http://www.karger.com/journals/bsi
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