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TYROSINE DOES NOT ENHANCE TANNING IN PIGMENTED HAIRLESS MICE
Author(s) -
Agin Patricia Poh,
Wilson Diane K.,
Shorter Gwendolyn G.,
Sayre Robert M.
Publication year - 1983
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1111/j.1751-1097.1983.tb04518.x
Subject(s) - hairless , irradiation , absorbance , dermis , tyrosine , melanin , chemistry , epidermis (zoology) , dermatology , biochemistry , biology , anatomy , medicine , chromatography , physics , nuclear physics
Pre‐tan products claiming to enhance pigmentation contain tyrosine as an‘active’ ingredient. Tyrosine is said to penetrate into the cell's metabolic pool, increasing the concentration of precursors essential to melanin formation, so that subsequent melanogenesis will be intensified. To address this theory, female pigmented hairless mice were irradiated three times weekly using FS‐20 lamps while receiving 0.01% tyrosine or 0.01% glycine either as a diet supplement or topically daily for 4 weeks. Control groups received the supplement or topical application without irradiation. Two additional groups were treated with a commercial pre‐tan enhancing product for 2 weeks prior to use of one group as a control, and the other irradiated as above. At the end of the experiment whole skin sections were taken for histological evaluation. Forward scattering absorbance spectrophotometry was performed on whole skin and separated epidermis. Comparison of averaged forward scattering absorbance spectra for each group revealed that there was no significant difference in the skin optics of any of the irradiated groups, while each irradiated group was significantly different from its non‐irradiated control. The spectra of all treated controls fell within pre‐established normal control limits. Histological evaluation by Fontana‐Masson staining showed that all irradiated groups had developed noticeable pigmentation not present in the controls. Of the groups receiving topical applications, the irradiated tyrosine group developed strikingly less pigmentation than did the irradiated glycine group. The irradiated pre‐tan product treated group was intermediate in the development of pigmentation. Melanocytes were visible throughout the dermis and epidermis of the irradiated groups, whereas only scattered dermal melanocytes were found in the controls. It appears that oral or topical tyrosine did not enhance pigmentation present with or without irradiation, detected optically or histologically.