Influence of depigmenting chemical agents on hair and skin color in yellow (pheomelanic) and black (eumelanic) mice.

Topical applications of monobenzylether of hydroquinone (MBEH) or intraperitoneal injections of phenol induced graying of hair in eumelanic mice but had little effect on hair color in pheomelanic mice. Amcinonide, an anti-inflammatory agent, elicited whitening of a few hairs in both pheomelanic and eumelanic mice. In phenol-treated eumelanic mice, damaged follicular melanocytes were uprooted from hair bulbs and incorporated into the developing hair. The fate of follicular melanocytes in MBEH- or amcinonide-treated mice was not determined since hair growth and graying were more variable than in phenol-treated mice. In contrast to the susceptibility of eumelanic hair follicles to depigmentation by phenol or MBEH, the tail skin of eumelanic or pheomelanic mice was not depigmented by these agents. Overall, during the 3 week period of treatment that was sufficient for phenol or MBEH to elicit graying of hair, epidermal melanocytes of the tails of eumelanic or pheomelanic mice either failed to respond (phenol) or were stimulated in their "proliferative" and melanogenic activity (MBEH). In contrast, amcinonide brought about a marked reduction in the numbers of DOPA-positive epidermal melanocytes inhabiting the tails of eumelanic or pheomelanic mice. Amcinonide exerted a deleterious influence on the structure and function of tail epidermis. Its actions were partly reversed by simultaneous treatment with MBEH but not with prostaglandin (PGE2).