Thody A J, Higgins E M, Wakamatsu K, Ito S, Burchill S A, Marks J M
Department of Dermatology, University of Newcastle upon Tyne, U.K.
J Invest Dermatol. 1991 Aug;97(2):340-4. doi: 10.1111/1523-1747.ep12480680.
There are two types of melanin in mammals, the brownish black eumelanin and the reddish yellow pheomelanin. Eumelanin and pheomelanin are present in human hair and this study was carried out to see whether both pigments are also present in human epidermis. Samples of epidermis were obtained from suction blisters raised in the upper arm of 13 Caucasian subjects of skin types I, II, and III and analyzed for both eumelanin and pheomelanin using a procedure involving high-performance liquid chromatography. Eumelanin and pheomelanin were found in all epidermal samples and their relative proportions correlated well with those found in samples of hair taken from the same subjects. The lowest concentrations of eumelanin were found in subjects of skin type I, with higher levels in skin types II and III. The concentrations of pheomelanin were more variable and showed no relationship to skin type. Increases in the concentrations of both pigments occurred following PUVA therapy, but whereas the largest increases in eumelanin were seen in skin types II and III, the increases in pheomelanin showed little relationship to skin type. Unlike eumelanin, epidermal pheomelanin also showed little relationship to PUVA-induced tanning. The present findings could be particularly significant in view of recent suggestions that pheomelanin, rather than protecting the skin against UV radiation, may actually contribute to UV-induced skin damage.
哺乳动物体内有两种黑色素,呈棕黑色的真黑素和呈红黄色的褐黑素。真黑素和褐黑素存在于人类毛发中,本研究旨在探究这两种色素是否也存在于人类表皮中。从13名皮肤类型为I、II和III型的白种人受试者上臂的抽吸水疱中获取表皮样本,并采用高效液相色谱法对真黑素和褐黑素进行分析。在所有表皮样本中均发现了真黑素和褐黑素,其相对比例与取自同一受试者的毛发样本中的比例高度相关。I型皮肤受试者的真黑素浓度最低,II型和III型皮肤受试者的真黑素浓度较高。褐黑素的浓度变化更大,与皮肤类型无关。PUVA治疗后两种色素的浓度均升高,但真黑素浓度升高幅度最大的是II型和III型皮肤受试者,而褐黑素浓度的升高与皮肤类型关系不大。与真黑素不同,表皮褐黑素与PUVA诱导的晒黑也几乎没有关系。鉴于最近有观点认为褐黑素非但不能保护皮肤免受紫外线辐射,反而可能导致紫外线引起的皮肤损伤,目前的研究结果可能具有特别重要的意义。