Section of Anatomy and Physiopathology, Department of Clinical and Experimental Sciences, Viale Europa 11, 25123, Brescia, Italy.
Br J Dermatol. 2014 Feb;170(2):382-91. doi: 10.1111/bjd.12622.
Sun exposure is responsible for long-term clinical skin changes such as photoageing, photodamage and photocancers. Ultraviolet (UV)A wavelengths stimulate the production of reactive oxygen species (ROS) that may contribute to photoageing. To protect against oxidative stress, skin cells have developed several defence systems, including ROS and metal ion scavengers and a battery of detoxifying, haem-degrading and repair enzymes. Melatonin's antioxidant activity is the result of three different but complementary actions: (i) a direct action due to its ability to act as a free radical scavenger; (ii) an indirect action that is a consequence of melatonin's ability to reduce free radical generation (radical avoidance); and (iii) its ability to upregulate antioxidant enzymes.
In this study, we focused our attention on the prevention of photodamage, choosing melatonin as an antioxidant agent.
In the present study we analysed the effects of pretreatment of murine fibroblasts cells (NIH3T3) with melatonin (1 mmol L(-1) ) followed by UVA irradiation (15 J cm(-2) ). Thereafter, changes in components of the extracellular matrix and in some antioxidant enzymes (inducible and constitutive haem oxygenase) were evaluated.
We observed that UVA radiation caused altered expression of extracellular matrix proteins and induced the expression of inducible haem oxygenase. This increase was not sufficient to protect the cells from damage. Instead, melatonin pretreatment led to increased expression of haem-degrading enzymes and suppression of UVA-induced photodamage.
These results suggest that melatonin, as a modifier of the dermatoendocrine system, may have utility in reducing the effects of skin ageing.
阳光照射是导致皮肤长期临床变化的原因，如光老化、光损伤和光致癌。紫外线（UVA）波长刺激活性氧（ROS）的产生，这可能导致光老化。为了防止氧化应激，皮肤细胞已经开发了几种防御系统，包括 ROS 和金属离子清除剂以及一系列解毒、血红素降解和修复酶。褪黑素的抗氧化活性是由三种不同但互补的作用产生的：（i）由于其作为自由基清除剂的能力而产生的直接作用；（ii）由于褪黑素降低自由基生成的能力（自由基避免）而产生的间接作用；（iii）其上调抗氧化酶的能力。
在这项研究中，我们将注意力集中在预防光损伤上，选择褪黑素作为抗氧化剂。
在本研究中，我们分析了用褪黑素（1 mmol L(-1)）预处理小鼠成纤维细胞（NIH3T3），然后用 UVA 照射（15 J cm(-2)）后的变化。此后，评估了细胞外基质成分和一些抗氧化酶（诱导型和组成型血红素加氧酶）的变化。
我们观察到 UVA 辐射导致细胞外基质蛋白表达改变，并诱导诱导型血红素加氧酶的表达。这种增加不足以保护细胞免受损伤。相反，褪黑素预处理导致血红素降解酶的表达增加，并抑制 UVA 诱导的光损伤。
这些结果表明，褪黑素作为皮肤内分泌系统的调节剂，可能有助于减少皮肤老化的影响。
