Investigation of the 1064 nm Q-Switched Nd:YAG Laser on Collagen Expression in an Animal Model

Background and purpose: The objective of this study was to evaluate the changes of collagen expression and its possible molecular mechanism in the rat skin induced by 1064 nm Q-switched Nd:YAG laser treatments. Methods: The dorsal skin of Sprague-Dawley (SD) rats was irradiated with the 1064 nm laser at fluences of 0, 0.6, 1.5, and 2.5 J/cm(2), respectively. Then biochemical analysis was used to quantify hydroxyproline content in the skin. The mRNA expressions of procollagen, matrix metalloproteinases (MMPs), and tissue inhibitors of metalloproteinases (TIMPs) were analyzed by using reverse transcription-polymerase chain reaction (RT-PCR). The activities of mitogen-activated protein kinase (MAPK) family members were detected by Western blot analysis. Results: The 1064 nm laser treatments led to a marked increase in collagen content in a dose-dependent manner. The expression of types I and III collagen, TIMP1 and TIMP2, in the skin was markedly upregulated, whereas the expression of MMP2 and MMP3 was significantly decreased after laser treatments. Both extracellular signal-related kinase (Erk)1/2 and JNK MAPK pathways were activated by the 1064 nm laser irradiation. Conclusions: The 1064 nm laser irradiation could markedly increase collagen synthesis and inhibit collagen degradation. The activation of Erk1/2 and JNK MAPK seems to play a role in collagen production in the rat skin, induced by the 1064 nm laser.