Skin Rejuvenation With Q-switched 1064-nm And 532-nm Nd: YAG Laser: A Comparative Study On Rat Model

Background/purpose:To compare the effects of the Q-switched 532-nm Nd:YAG and Q-switched 1064-nm Nd:YAG laser in non-ablative treatments on rat skin in vivo,and discuss the mechanism of non-ablative rejuvenation. rejuvenation,in order to offer references for effective clinical treatment.Methods:Eighteen Rats were randomly divided into two groups,each rat's back were shaved,then separated three treatment areas and one control area. One group received irradiation of Q-switched 532-nm Nd:YAG laser,the other group received irradiation of Q-switched 1064-nm Nd:YAG laser.,three different energy levels of the two kinds of laser for each group were applied for four times at a interval of one days,with 10%overlap.Rat's biophysical parameter measurements of skin elasticity and water content were carried out with MPA(multi probe adapter)at 1,2,3 and 4 weeks after the last irradiation. Skin specimens were taken for hydroxyproline content assay,histological study.Three antioxidative parameters(SOD super oxide dismutase,MDA malondialdehyde and GSH reduced glutathione hormone)were also measured.Results:The skin elasticity and water content improved increasingly according to the MPA measurements of the two group 4 weeks after the last irradiation.The hydroxyproline of the skin in the Q-switched 1064-nm Nd:YAG laser of 0.6J/cm~2,1.5 J/cm~2 and 2.5 J/cm~2 group showed 7.1%,13.1%and 19.8% (p＜0.05)increase respectively compared to their controls,the enhancement of dermal thickness were 15.5%,29.7%and 38.4%;The hydroxyproline of the skin in the Q-switched 532-nm Nd:YAG laser of 0.5J/cm~2,1.2 J/cm~2 and 2.0 J/cm~2 group showed 6.9%,9.6%and 14.2%(p＜0.05)increase respectively compared to their controls,the enhancement of dermal thickness were 5.5%,15.1%and 29.9%,among which the Q-switched 1064-nm laser group had the greatest effect. The result of antioxidative parameters showed some juvenescence change at the radiated skin.Conclusion:the Q-switched 532-nm Nd:YAG and Q-switched 1064-nm Nd:YAG laser can both improve skin elasticity and enhance dermal collagen content, inducing non-ablative rejuvenation,but the Q-switched 1064-nm laser has greater effect than the Q-switched 532-nm laer.