ABSTRACT
Objective: To detect the expression of MMP-13 in the skin of mice treated by near-infrared (IRA) and ultraviolet (UV) so as to observe their effects on skin photoaging and their interrelation and explore molecular mechanisms in IRA-induced skin photoaging. Methods: Male ICR mice were randomly divided into five groups: control group (without ray exposure), IRA group, UV group, IRA/UV group, and UV/IRA group. The mice in the latter four groups had their dorsal skin exposed to different radiated ray respectively. The levels of MMP-13 protein and mRNA in the exposed skin were detected by HE, immunohistochemical method, Western blot and real-time PCR. Results: Both skin lesions by visual inspection and H&E staining results showed that mice in the other four groups had skin photoaging in the exposed skin area compared with the control group. The levels of MMP-13 protein and mRNA in the exposed skin in IRA/UV and UV/IRA groups were significantly higher than those in the control mice (P<0.05). In addition, mice in IRA/UV group showed higher levels of MMP-13 protein and mRNA than those in UV/IRA group (P<0.05). Conclusion: ① IRA causes skin photoaging in mice. ② UV and IRA interact with each other, up-regulate the expression of MMP-13, and promote each other in the process of photoaging. ③ The effects of IRA and UV in combination on skin photoaging are closely related to order of exposure. Taken together, avoiding IRA exposure and the expression of MMP-13 play an important role in preventing skin wrinkle formation and treatment of photoaging in mice.