| Part Ⅰ:Effect of Low-energy Q-switched 1064nm Nd:YAG Laser on Mice Skin Barrier and CollagenObjective:To investigate the non-ablative skin rejuvenation influence that low-energy Q-switched 1064nm Nd:YAG laser exerts on the dorsal skin of mice and to study its effect on skin elasticity, moisture, stratum corneum and other skin barrier function of mice dorsal skin.Methods:40 BALB/c mice were selected and randomly divided into 4 groups, with 10 mice at each time point. Each BALB/c mouse dorsal skin’s hair were waxed off by scissors and depilatory creams and the dorsal skin was averagely divided into four areas 24 hours after hair removal, which were 0,1,1.5 and 2J/cm2 energy treatment area respectively, wherein 0J/cm2 energy treatment area was the control group. Other laser irradiation parameters were 5ns pulse width,6mm light spot and the light spots had a 10% overlap. Before laser irradiation, mice received intraperitoneal injection anesthesia of chloral hydrate (1 mL/kg). The mice were irradiated twice a week lasting 4 weeks. Related tests were conducted immediately after the last irradiation respectively on day (0),7,14,21 and 28, which in total had five time points. After skin transdermal water loss (TEWL), skin moisture and elasticity of the skin of 0 days group were tested by multi-probe test system, they continued to survive, and the mice were put to death respectively on day 7,14,21 and 28 for subsequent tests.Results:① Skin elasticity test results showed that they decreased significantly immediately after the laser treatment of skin elasticity (p<0.05), regained on day 7, while on day 21 to 28, the skin elasticity significantly enhanced (p<0.05).② Skin moisture test results:the results tested immediately after the laser treatment showed that 2J/cm2 energy group’s water content increased compared with the control group (p<0.05), and the results returned to normal on day 7. On day 21, the water content of 1.5 J/cm2 and 2 J/cm2 treatment group (p<0.05) increased, while on day 28, the water content of all laser groups increased more significantly than all control groups (p<0.05). ③ Hydroxyproline content test results:after 21 days, hydroxyproline content of 1.5 J/cm2 and 2J/cm2 treatment group increased (p<0.05), and this trend continued until day 28 days, hydroxyproline content of 1J/cm2,1.5J/cm2 and 2 J/cm2 treatment group increased more significantly than control groups (p<0.05). ④ Values of TEWL increased significantly immediately after treatment and tend to return normal after terminating treatment for 7 days, but the values were still significantly higher than control groups (p<0.05). From day 14 to 28, the TEWL value returned to normal with no significant difference compared to control groups (p>0.05).⑤ On the seventh days after laser treatment, the expression of K-10 (2J/cm2, p= 0.000) and Fillagrin were decreased (p<0.05), but returned to normal on day 21 and had no significant difference compared with control groups (p> 0.05).Conclusion: ① The low-energy Q-switched 1064nm Nd:YAG laser had the effects of promoting mouse dorsal skin collagen proliferation and increasing skin elasticity and moisture, so as to achieve rejuvenation effects. ② In different energy intensities, 1.5 J/cm2 and 2J/cm2 strength group had better effects. ③ Low-energy Q-switched 1064nm Nd:YAG laser irradiation had minor damage on the skin barrier, but it could quickly recover in a short time. water content of all laser groups increased more significantly than all control groups (p<0.05). ③ Hydroxyproline content test results:after 21 days, hydroxyproline content of 1.5 J/cm2 and 2J/cm2 treatment group increased (p<0.05), and this trend continued until day 28 days, hydroxyproline content of 1J/cm2,1.5J/cm2 and 2 J/cm2 treatment group increased more significantly than control groups (p<0.05). ④ Values of TEWL increased significantly immediately after treatment and tend to return normal after terminating treatment for 7 days, but the values were still significantly higher than control groups (p<0.05). From day 14 to 28, the TEWL value returned to normal with no significant difference compared to control groups (p>0.05).⑤ On the seventh days after laser treatment, the expression of K-10 (2J/cm2, p= 0.000) and Fillagrin were decreased (p<0.05), but returned to normal on day 21 and had no significant difference compared with control groups (p> 0.05).Conclusion: ① The low-energy Q-switched 1064nm Nd:YAG laser had the effects of promoting mouse dorsal skin collagen proliferation and increasing skin elasticity and moisture, so as to achieve rejuvenation effects. ② In different energy intensities, 1.5 J/cm2 and 2J/cm2 strength group had better effects. ③ Low-energy Q-switched 1064nm Nd:YAG laser irradiation had minor damage on the skin barrier, but it could quickly recover in a short time.Part Ⅱ:Study of Low-energy Q-switched 1064nm Nd:YAG Laser Irradiation’Effects on MMPs, TGFβ1/smad and NF-κB p65 signaling pathwayObjective:To investigate the impacts and significance of low-energy Q-switched 1064nm Nd:YAG laser on MMPs expression in mice skin and its relationship with TGFβ1/smad and NF-κB p65 signaling pathway.Methods:40 BALB/c mice were selected and conducted hair removal in mice dorsal skin. The dorsal skin of the mice were divided into four areas with neutral red which were respectively 0,1,1.5 and 2 J/cm2 energy treatment area, wherein 0J/cm2 energy treatment area was control group. Other laser irradiation parameters were 5ns pulse width,6mm light spot and the light spots had 10% overlap. Before laser irradiation, mice received intraperitoneal injection anesthesia of chloral hydrate (1 mL /kg). The mice were irradiated twice a week lasting 4 weeks. Related tests were conducted immediately after the last irradiation respectively on day 7,14,21 and 28, which in total had four time points and each time point had 10 mice. RT-QPCR technique was applied to test the expression situation of MMPland MMP9 in the mice skin tissue under each time point and different irradiation intensities. Western Blot technique was applied to detect the protein expression situations of TGFβ1/smad and NF-κB p65 signaling pathway in 7d and 21 d groups.Results: ① RT-QPCR results showed that the expression of MMP1 mRNA after 14 days of the last treatment decreased (P<0.05) and this trend continued to21 days. The MMP9 mRNA expression of 1 J/cm2 group (p> 0.05),1.5 J/cm2 group (p<0.05) and 2 J/cm2 group (p<0.05) was significantly reduced on the 14th and 21th days after treatment. On day 28, MMP1 and MMP9 mRNA expression levels were back to normal.② Western Blot results showed that compared with the control group (0 J/cm2), TGFβRI expression increased significantly on the seventh day after laser treatment (p<0.05). The phosphorylation level smad2 at 1 J/cm2 group showed no significant change (p> 0.05), while those of 1.5 J/cm2and 2 J/cm2 groups significantly increased (p<0.05). On day 21 after laser treatment, TGFβRI expression of mouse skin and smad2 phosphorylation level significantly increased (p<0.05). ③ The phosphorylation level of NF-κB p65 on day 7 and 21 showed no significant difference (p> 0.05).Conclusion: ① The low-energy Q-switched 1064nm Nd:YAG laser caused the expression of MMP1 and MMP9 in the mice dorsal skin tissue decrease, thereby causing an increase in the expression of collagen.② The low-energy Q-switched 1064nm Nd:YAG had better effects on non-ablative laser skin rejuvenation of the mice dorsal skin under the optimized irradiation intensity in 1.5 J/cm2 and 2J/cm2 groups. ③Low-energy Q-switched 1064nm Nd:YAG’s effects on non-ablative laser skin rejuvenation effect on mouse dorsal skin was probably caused by starting TGFβ1 /smad signaling pathway.④There was no relation between it and the NF-κB p65 signaling pathway. |
PDF Full Text Request