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Spontaneous occurrence of photoageing‐like phenotypes in the dorsal skin of old SAMP1 mice, an oxidative stress model

Skin photoageing is a complex, multifactorial process and both intrinsic and extrinsic factors may contribute to its pathogenesis. The ultraviolet‐irradiated hairless mouse has been used as an animal model for photoageing, but this model mimics only the ‘extrinsic’ aspects. Here, we show that skin from old SAMP1 mice, a model for higher oxidative stress and senescence acceleration, exhibited histological and gene expression changes similar to those in human photoaged skin without ultraviolet irradiation. These changes include an increase in elastic fibre and glycosaminoglycan histologically, an upregulation of several proinflammatory cytokines and matrix metalloproteinases, and an increase in lipid peroxide. We propose that SAMP1 mice are a spontaneous animal model for photoageing caused by an exaggerated intrinsic mechanism, namely, higher oxidative status. This mouse model is useful to explore the link between oxidative stress and photoageing, and to evaluate the efficacy of antioxidants.