Differential analysis of experimental hypermelanosis induced by UVB, PUVA, and allergic contact dermatitis using a brownish guinea pig model.

摘要: In moderately colored guinea-pig skin, UVB, PUVA, and allergic contact dermatitis were shown to induce hyperpigmentation that resembled the pigmentary changes observed in mongoloid human skin. Using this model, we examined effects of chemical agents, including tyrosinase inhibitors sunscreen on color induced by UV irradiation. The daily exposure brownish skin UVB irradiation at a variety energies for 3 successive days clearly visible black pigmentation irradiated rectangular areas flank within few irradiation, maximum being reached about 1 week after i.e., similar occur pigmented Split epidermal sheets prepared from untreated guinea pigs exhibited 200-400 melanocytes/mm2; applied show an increased number strongly dopa-positive melanocytes with stout dendrites (800-1,000 cells/mm2). UVA following intraperitoneal injection 8-methoxypsoralen (8-MOP) also produced was paralleled marked increase dopa-reacted split sheets. Allergic application 1-phenylazo-2-naphthol interval 14 10 21 allergy-acquiring animals examined. This accompanied as compared seen controls. contrast, dinitrochlorobenzene failed such high ratio postpigmentation, only showing 5 depigmentation; latter, there slight decrease melanocytes. To study preventive effect tyrosine UVB-induced pigmentation, topical applications these compounds performed three irradiations. Treatment 10% hydroquinone interrupted resulted reduction found UVB-irradiated, control