P19 INFLUENCE OF MELATONIN AND MELATONIN ANTAGONISTS ON HAIR SHAFT LENGHT AND PROLIFERATION IN CULTIVATED HUMAN HAIR FOLLICLES

Fischer T.W., Fischer A., Knöll B., Hipler U.C., Elsner P. Department of Dermatology, Friedrich-Schiller-University, Jena, Germany

Melatonin has different effects concerning human cell proliferation. It was shown by others that it both inhibits and stimulates keratinocyte proliferation in vitro. The influence of melatonin on human hair follicle lenght and proliferation was investigated in this study. Human anagen hair follicles were isolated from healthy human scalp skin under the stereo dissecting microscope by means of watchmakers´ foreceps. Isolated follicles were put into single wells of a 24-multi-well-plate, feeded with 500µl Willliam´s E medium with usual supplements and maintained at 37°C and 5% CO²/95% air. Test solutions were prepared with the feeder medium and melatonin in concentrations of 20, 30, 40µmol and 1, 2, 3 and 5mmol. Hair growth was measured by microscope using an eye-piece micromeasurement scale. The proliferation was assessed by ki-67 staining. Melatonin inhibited hair growth compared to feeder medium at concentrations of 1 to 5 mmol and this was statistically significant for 1 mmol over 6 days (p#0.05). In contrary, 30Fmol melatonin lead to an increased growth compared to medium over the first 2 days (p#0.005). Melatonin and its antagonist 4-PDOT (30Fmol each) lead to a significant inhibition of hair follicle growth over 6 days (p#0.001). This could be confirmed by ki-67 staining of hair follicles. We could show a distinct dose-dependency of melatonin on inhibition and proliferation on human hair follicle growth, respectively. This was reproducible by specific inhibition of melatonin by an antagonist at a dose of 30µmol.