Shindo Y, Witt E, Packer L
Department of Molecular and Cell Biology, University of California, Berkeley 94720.
J Invest Dermatol. 1993 Mar;100(3):260-5. doi: 10.1111/1523-1747.ep12469048.
A comprehensive comparison of antioxidant defenses in the dermis and epidermis and their response to exposure to ultraviolet (UV) irradiation has not previously been attempted. In this study, enzymic and non-enzymic antioxidants in epidermis and dermis of hairless mice were compared. Enzyme activities are presented both as units/gram of skin and units/milligram of protein; arguments are presented for the superiority of skin wet weight as a reference base. Catalase, glutathione peroxidase, and glutathione reductase (units/gram of skin) were higher in epidermis than dermis by 49%, 86%, and 74%, respectively. Superoxide dismutase did not follow this pattern. Lipophilic antioxidants (alpha-tocopherol, ubiquinol 9, and ubiquinone 9) and hydrophilic antioxidants (ascorbic acid, dehydroascorbic acid, and glutathione) were 24-95% higher in epidermis than in dermis. In contrast, oxidized glutathione was 60% lower in epidermis than in dermis. Mice were irradiated with solar light to examine the response of these cutaneous layers to UV irradiation. After irradiation with 25 J/cm2 (UVA + UVB, from a solar simulator), 10 times the minimum erythemal dose, epidermal and dermal catalase and superoxide dismutase activities were greatly decreased. alpha-Tocopherol, ubiquinol 9, ubiquinone 9, ascorbic acid, dehydroascorbic acid, and reduced glutathione decreased in both epidermis and dermis by 26-93%. Oxidized glutathione showed a slight, non-significant increase. Because the reduction in total ascorbate and catalase was much more severe in epidermis than dermis, it can be concluded that UV light is more damaging to the antioxidant defenses in the epidermis than in the dermis.
此前尚未尝试对真皮和表皮中的抗氧化防御机制及其对紫外线（UV）照射的反应进行全面比较。在本研究中，对无毛小鼠表皮和真皮中的酶促和非酶促抗氧化剂进行了比较。酶活性以每克皮肤的单位数和每毫克蛋白质的单位数表示；文中阐述了以皮肤湿重作为参考基准的优势。过氧化氢酶、谷胱甘肽过氧化物酶和谷胱甘肽还原酶（每克皮肤的单位数）在表皮中的含量分别比真皮高49%、86%和74%。超氧化物歧化酶则不遵循此模式。亲脂性抗氧化剂（α-生育酚、泛醇9和泛醌9）和亲水性抗氧化剂（抗坏血酸、脱氢抗坏血酸和谷胱甘肽）在表皮中的含量比真皮高24% - 95%。相比之下，氧化型谷胱甘肽在表皮中的含量比真皮低60%。用太阳光照射小鼠，以检查这些皮肤层对紫外线照射的反应。在用25 J/cm²（来自太阳模拟器的UVA + UVB，是最小红斑剂量的10倍）照射后，表皮和真皮中的过氧化氢酶和超氧化物歧化酶活性大幅下降。α-生育酚、泛醇9、泛醌9、抗坏血酸、脱氢抗坏血酸和还原型谷胱甘肽在表皮和真皮中的含量均下降了26% - 93%。氧化型谷胱甘肽略有增加，但无统计学意义。由于表皮中总抗坏血酸和过氧化氢酶的减少比真皮严重得多，因此可以得出结论，紫外线对表皮抗氧化防御机制的损害比对真皮的更大。
