中文摘要：

目的研究低能量密度Q开关1064nmNd：YAG激光对小鼠皮肤屏障、基质金属蛋白酶的影响，探讨其嫩肤机制和最佳能量。方法分别用1，1．5和2J／cm。能量密度的激光照射BALB／c小鼠背部皮肤，光斑直径6ram，2次／周，连续4周，未照射组作为对照，分别于照射即刻，照射后7，14，21和28d时检测其皮肤弹性、皮肤水分及经皮水分丢失（TEWL）值、羟脯氨酸含量，定量PCR法和Westernblot法分别检测其基质金属蛋白酶（MMP）1和MMP9，Keratin-10（K-10）和Filaggrin水平。结果激光照射后即刻皮肤弹性下降，皮肤含水量仅在2J／cm。组上升，但照射7d后与对照比较无差异，从21d开始持续至28d，皮肤弹性、含水量和羟脯氨酸含量均明显增加，差异有统计学意义（P〈0．05）。照射后即刻持续至7d，TEwL明显增加，照射后7dK-10和Filaggrin明显减少，差异有统计学意义（P〈0．05），但从14d开始至28d，与对照差异均无统计学意义（P〉0．05）。照射后14d，MMPl和MMP9mRNA明显下降，持续至21d（P〈0．05），至28d恢复正常（P〉0．05）。结论低能量Q开关1064nmNd：YAG激光通过下调MMPs蛋白水平和促进胶原蛋白新生增加皮肤弹性和含水量，从而达到嫩肤作用，且能量为1．5和2J／cm。时效果较好。

英文摘要：

Objective To investigate low-energy Q-switched 1 064nm Nd：YAG laser on skin barrier and matrix metal- loproteinase in order to provide the basis for the selection of optimal energy density, and to explore the mech- anisms whereby this laser rejuvenates skin. Methods The dorsal skin of BALB/c mice was treated with 1, 1.5 and 2J/cm2 energy densities, at a spot size of 6mm in diameter twice a week for 4 weeks. The untreated mice served as controls. Skin elasticity, stratum corneum hydration, transepidermal water loss （TEWL） and hydroxyproline content were assessed immediately, 7,14,21, and 28 days after laser treatment. Both m RNA and protein levels of MMP1 ,MMP9, Keratin-10 （K-10） and filaggrin were measured using quantitative PCR and Western blot. Results Immediately after laser irradiation, skin elasticity decreased and stratum corne- um hydration increased at 2J/cm2. After 7 days of laser treatment, there was no difference in either skin elas- ticity or stratum cornenm hydration between treated and untreated mice. After 21 days of treatment,the elas- ticity, stratum comeum hydration and hydroxyproline content increased significantly （ P 〈 0. 05 ）. The TEWL levels remained elevated from day 0 to 7 after treatment （P 〈 0. 05）. Afterward TEWL declined to the levels comparable to untreated controls after 14 days of treatement （ P 〉 0. 05 ）. On day 7, the levels of K-10 and filaggrin were significantly reduced （ P 〈 0. 05 ）, and returned to normal levels on day 21 （ P 〉 O. 05 ）. More- over, mRNA levels of MMP1 and MMP9 decreased significantly （P 〈 O. 05 ）following 14 to 21 days of irradi- ation, and returned to normal by day 28 （P 〉 0. 05）. Conclusion The low-energy Q switch 1 064nm Nd： YAG laser induced rejuvenation could be via stimulating collagen production, increasing elasticity and stratum corneum hydration.and reducing MMPs. The energy levels of 1.5 and 2J/cm2 are more effective.