Human hair follicle pigmentary unit as a direct target for modulators of melanogenesis, as studied by [14C]-2-thiouracil incorporation.
The purpose of this study was to evaluate human hair follicle melanogenic activity using the [14C]-2-thiouracil, which was known to incorporate into nascent melanins. Results obtained on pigmented, grey and non-pigmented hair follicles demonstrated that [(14)C]-2-TU incorporation was restricted to the melanogenic compartment with a strong accumulation located around dermal papilla and within the fibre of pigmented hair follicles. Quantitative analysis of [(14)C]-2-TU incorporation showed a significant increase in pigmented hair follicles upon stimulation with 1 microm forskolin concomitant to an increase in tyrosinase levels. A strong significant decrease in [14C]-2-TU incorporation was noted, when hair follicles were incubated with the tyrosinase competitive inhibitor kojic acid (200 microm). Incubation with the MC1-R agonist alpha-MSH (0.2 microm) did not induce a significant stimulation of hair melanogenesis. The present model could thus represent a useful new tool to identify modulators of human hair pigmentation.
Michelet
Jean-François
JF
L'Oréal Recherche, Clichy, France. jfmichelet@rd.loreal.com
Gautier
Brigitte
B
Gaillard
Olivier
O
Bernard
Bruno Alain
BA
Benech
Florence
F
D001706:Biopsy; D002250:Carbon Radioisotopes; D005576:Colforsin / Q000494:pharmacology; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D018859:Hair Follicle / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D006801:Humans; D008543:Melanins / Q000378:metabolism*; D008875:Middle Aged; D014442:Monophenol Monooxygenase / Q000037:antagonists & inhibitors / Q000378:metabolism; D011753:Pyrones / Q000494:pharmacology; D044102:Receptor, Melanocortin, Type 1 / Q000819:agonists; D012880:Skin Pigmentation / Q000187:drug effects / Q000502:physiology*; D013889:Thiouracil / Q000378:metabolism*; D000521:alpha-MSH / Q000494:pharmacology
D002250:Carbon Radioisotopes; D004791:Enzyme Inhibitors; D008543:Melanins; D011753:Pyrones; D044102:Receptor, Melanocortin, Type 1; D005576:Colforsin; D000521:alpha-MSH; D013889:Thiouracil; C011890:kojic acid; D014442:Monophenol Monooxygenase; D017868:Cyclic AMP-Dependent Protein Kinases