Q-Switched 1,064-nm Neodymium-Doped yttrium aluminum garnet laser irradiation induces collagen remodeling in SKH-1 Hairl ess mice by activating ERK1/2 and p38MAPK signaling pathway

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.

Keywords:
SKH-1 hairless mice; 1064 nm Q-switched Nd:YAG laser; collagen remodeling; ERK ½; p38MAPK signaling pathways