Gilchrest B A, Blog F B, Szabo G
J Invest Dermatol. 1979 Aug;73(2):141-3. doi: 10.1111/1523-1747.ep12581580.
Both aging and sun exposure have well-documented effects on the human melanocyte system. Paired biopsies of habitually exposed and nonexposed skin from adjacent anatomic sites were obtained from 8 donors aged 28 to 80 yr in order to study the combined effect of chronic actinic irradiation and chronologic aging. Density of dopa-positive melanocytes was roughly twofold higher in the exposed than in the nonexposed skin at all ages, suggesting an irreversible effect of sun exposure. Melanocyte density declined approximately 6 to 8% of the surviving population per decade in both sites. Dopa-positivity of individual melanocytes was consistently greater in the chronically exposed skin than in the nonexposed skin of the same subject and did not vary with age. These data strengthen and expand earlier observations of age-related melanocyte changes, and explain the apparent paradox of a generalized increase in pigmentation and simultaneous decrease in melanocyte density which frequently accompany advancing age. In addition, the present study suggests that the principal effect of chronic sun exposure on the human pigmentary system is not premature "aging" as currently recognized histologically, but rather activation and/or proliferation of the exposed melanocytes.
衰老和阳光照射对人类黑素细胞系统的影响都有充分的文献记载。从8名年龄在28至80岁的供体身上获取相邻解剖部位习惯性暴露皮肤和未暴露皮肤的配对活检样本，以研究慢性光化辐射和自然衰老的联合作用。在所有年龄段，多巴阳性黑素细胞的密度在暴露皮肤中比未暴露皮肤中大约高两倍，这表明阳光照射具有不可逆的影响。在两个部位，黑素细胞密度每十年大约下降存活群体的6%至8%。同一受试者中，长期暴露皮肤中单个黑素细胞的多巴阳性始终高于未暴露皮肤，且不随年龄变化。这些数据强化并扩展了早期关于与年龄相关的黑素细胞变化的观察结果，并解释了随着年龄增长色素沉着普遍增加和黑素细胞密度同时下降这一明显的矛盾现象。此外，本研究表明，慢性阳光照射对人类色素系统的主要影响并非如目前组织学上所认识的过早“衰老”，而是暴露的黑素细胞的激活和/或增殖。
