| Background and Objective:To compare the histological and ultrastructural change of Wistar rat skin after the irradiation of Q-switched1064nm Nd:YAG laser and intense pulsed light (IPL), and to explore the long-term of therapeutic effect and the treatment interval, thus providing a theoretical basis for the clinical application.Method:Depilating dorsum skins of40clean Wistar rats and randomly divided the skins into3groups by Picric Acid labeling.Nearly cephalic region is the normal control group; Interzonal region is the IPL group(spot size10mm×30mm, energy density18J/cm2,pulse width6ms,pulse delay30ms); Nearly caudal region is the YAG group(spot diameter6mm, energy density3.0J/cm2,pulse frequency10Hz).Both of the lights irradiated rat skins once and repeated three times. Rat skin samples were taken separately1day,3days,5days,1week,2weeks,3weeks,4weeks,8weeks,12weeks after irradiation, and then Image-pro Plus image analysis system, ELISA kits, and Real-time PCR method were applied to detect the thickness of the dermis, hydroxyproline and the expression of III procollagen mRNA respectively. The ultra-structure changes of rat skin were observed by transmission electron microscopy (TEM) at3weeks after the irradiation.Results:After the irradiation of Q-switched1064nm Nd:YAG laser (YAG group) and IPL (IPL group),①.2to12weeks later, the dermal thickness of Wistar rats in two groups had increased when compared with that in the normal control group (P<0.05),4to12weeks later, the dermal thickness of rats in YAG group had increased more than that in the IPL group, the difference was statistically significant (P<0.05);②.1week later, the hydroxyproline of rats in two groups increased more than that in the control group, and reached the maximum after4weeks(P<0.05);12 weeks later, the hydroxyproline in both groups were significantly decreased than that in the4th week, but still higher than that in the control group (P<0.05); the hydroxyproline contents in the two groups of irradiation after4weeks were significantly different from that in the2nd week(P<0.05).③.3to5days after irradiation, the expression of Ⅲ procollagen mRNA in the two groups were significantly lower than that in the normal control group (P<0.05);2weeks later, the expression of Ⅲ procollagen mRNA in the two groups were significantly increased (P<0.05);3to12weeks later, the expression of Ⅲ procollagen mRNA in the two groups began to decrease, the expression in the IPL group decreased to the normal point after3weeks,12weeks after irradiation the expression in YAG group was still higher than that in the IPL group and normal control group (P<0.05);④.3weeks later, when rat skin was observed by transmission electron microscopy, a denser arrangement of collagen was found in the rat skin of two experimental groups than that in the normal control group, and the number of collagen per unit was increased significantly.Conclusion:Collagen synthesis and remodeling were occurred after both kinds of irradiation, and the effect could last for at least3months, Q-switched1064nm Nd: YAG laser had a stronger effect than the IPL; the remodeling effect of lights with different wavelengths had something to do with the depth of penetration; to the two kinds of lights, the best referential treatment interval is2weeks for the non-ablative skin rejuvenation of rat skin. Objective:To investigate the effect and the meaning of Q-switched1064-nm Nd:YAG laser and intense pulse light on heat shock protein70(HSP70)expression in Wistar Rat Skin.To research the possible molecular mechanisms of QS1064nm Nd: YAG laser and intense pulsed light irradiation induces skin collagen synthesis by stimulating PTEN/Akt/P70S6Kinase signaling pathway.Methods:Depilating dorsum skins of40clean Wistar rats and randomly divided the skins into3groups by Picric Acid labeling.Nearly cephalic region is the normal control group; Interzonal region is the IPL group(spot size10mm×30mm, energy density18J/cm2,pulse width6ms, pulse delay30ms); Nearly caudal region is the YAG group(spot diameter6mm, energy density3.0J/cm2,pulse frequency lOHz).Both of the lights irradiated rat skins once and repeated three times. Using immunohistochemical staining to detected expression of HSP70of rat skin samples at1day,1week,4-week after irradiation. Using western blot to detect the expression of PTEN, p-Akt and p-P70S6Kinase protein at24hours after irradiation.Results:Immunohistochemical reveals that in1day after the irradiations of Q-switched1064-nm Nd:YAG laser or intense pulse light, the expression of HSP70was enhanced compared with normal control group(p<0.05),and was most significant after1week;4weeks after the irradiations, the expression of HSP70was reduced, there was no difference between IPL group and normal control group in expression, and YAG group is still higher in contrast to normal control group(p<0.05); the difference between IPL group and YAG group in1day,1week, and4weeks after the irradiations is statistical significant(P<0.05). The results of western blot reveals that the expression of PTEN of the YAG group and the IPL group on rat skin were significantly decreased than the normal control group at24hours after irradiation(P <0.05), the expression of p-Akt and p-P70S6Kinase was increased significantly than the normal control group (P<0.05).and the YAG group was increased significantly than the IPL group (P<0.05).Conclusion:HSP70may play an important role in the generation of new collagen of rat skin which being irradiated with Q-switched1064nm Nd:YAG laser and intense pulsed light.The expression level of HSP70is related to the extent and depth of thermal damage in tissue after irradiations.PTEN/Akt/P70S6Kinase signaling pathway is activated by irradiation of QS-1064nm Nd:YAG laser and IPL, and the pathway may play an important role in the generation process of the collagen. |
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