Abstract
To select the optimal condition of 1064 nm Q-switched Nd:YAG laser irradiation and study the molecular mechanism of laser irradiation for skin rejuvenation. Sixty male, 6-week-old SKH-1 hairless mice were equally divided into 6 groups: 3d, 7d, 21d, 28d, 42d and 56d of 1064 nm laser irradiation at both 0 J/cm2 (left region) and 1.5 J/cm2 (right region) fluence. The basic skin performances were analysed via quantifying hydroxyproline content and skin hydration in the dermis and epidermis. The Collagen I, MMP2 and TIMP1, as well as ERK 1/2, p38MAPK, JNK and ERK5 signaling pathways levels were detected by qRT-PCR. Laser irradiation led to a marked increase in hydroxyproline content and skin hydration in the dermis and epidermis compared to the non-irradiated area. After laser irradiation, collagen I was markedly up-regulated, MMP2 was significantly decreased and TIMP1 was unchanged. Moreover, qRT-PCR results revealed ERK 1/2 and p38MAPK signaling pathways were activated after laser irradiation. we are firstly proves that 1064 nm laser irradiation can inhibit collagen degradation by stimulating the activation of ERK1/2 and p38MAPK signaling pathways. Additionally, the condition of laser irradiation lasting 21d at fluence of 1.5 J/cm2 displays the best effect of skin rejuvenation in our study.
Highlights
Skin aging is divided into natural aging and photo-aging
In Low-Level Laser Terapy (LLLT) enhancing wound healing and stimulating cell proliferation of fibroblast and endothelial cells, Extracellular signal-Regulated Kinase (ERK) and Mitogen-Activated Protein Kinase (MAPK) phosphorylation were increased while the TNF/CHX‐increased p38 MAPK, Jun N-terminal kinases (JNK), IKK phosphorylation, NF-κB translocation, and iNOS expression was suppressed
The quantitative reverse transcription-polymerase chain reaction (qRT-PCR) results showed an increased expression level of collagen I (P < 0.01), reduced expression level of matrix metalloproteinase (MMP)-2 (P < 0.05), and unchanged expression level of tissue inhibitors of metalloproteinase (TIMP)-1(P > 0.05) in dermis and epidermis from 1064-nm Nd: YAG laser irradiation region compared to non-irradiated region (0 J/cm2) (Figure 2)
Summary
Skin aging is divided into natural aging (genetic factor) and photo-aging (environmental factor). 1064 nm Q-Switched Nd:YAG laser was used to irradiate the dorsal skin of BABL/c mice with 0, 1, 1.5 and 2 J/cm energy level and lasting for 7, 14, 21, and 28 days, respectively They found from 21 days to 28 days, the skin elasticity, moisture content, hydroxyproline content, and gene expression of types I and III procollagen increased significantly. In Low-Level Laser Terapy (LLLT) enhancing wound healing and stimulating cell proliferation of fibroblast and endothelial cells, ERK and Mitogen-Activated Protein Kinase (MAPK) phosphorylation were increased while the TNF/CHX‐increased p38 MAPK, JNK, IKK phosphorylation, NF-κB translocation, and iNOS expression was suppressed This showed that LLLT protects against inflammatory-induced endothelial dysfunction by suppressing p38MAPK signaling (Chu et al, 2018). The signal pathway performances were detected by the RNAs of ERK1/2, p38MAPK, JNK and ERK5 using qRT-PCR
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