二氧化碳点阵激光治疗光老化大鼠皮肤的实验分析

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1、ABSTRACTcontributestothegenerationofreactiveoxygenspecies(ROS)thatstimulatetheinflammatoryprocessintheskin，activatingtranscriptionfactorsthatregulatetheproteolyticdegradationoftheextracellularmatrix(ECM)．AninterlinkednetworkofenzymesthatconvertROStoha

2、rmlesswaterandoxygenmoleculesregulatestheantioxidantdefensesystem，whichisreducedintheskinofagingindividuals．Histologicalchangesincludeareducedsurfacecontactbetweentheepidermisanddermis，whichresultsinareducedexchangeofnutrientsandmetabolitesbetweenthet

3、woskinlayersExtrinsicallyagedskinisalsocalledSkinphotoaging，whichischaracterizedbysignssuchaswrinkles，dyspigmentedlesions，teleangiectasiaandlossofelasticity．Histologicalanalysisofphoto—damagedskinshowsepidermisathickeningorthin，blackelementcellprolife

4、rationorreduce，leathercapillaryarrayofdisordeLinflammatorycellsinfiltrationandextmcellularmatrixcomponentschange，themajormodificationsinthedermisincludingtheformationofsolarelastosis．UVradiationcandown-regulatetheexpressionofTGF—porTGF—preceptorandres

5、ultinthereductionorapoptosisoffibroblastsaswellastheactivationofAP一1byblockingTGF-b／Smadandp38MAPKsignalingpathways．ThechangesoffibroblastsandAP一1respectivelyincreasetheexpressionofMMPs，CathepsinG,serineproteases，fibroblastelastase，freeradicals，ROSetc

6、，whichcanleadtocollagenorelastinproductiondecreasingaswellascollagenandECMbreakdownincreasing，，leadingtoepidermalinvaginationrepresentingthebeginningofwrinkles．Inagedskin，MMPsmayalreadyexistinamoreactivestatebecauseofthedecreasedlevelsoftissueinhibito

7、rsofMMPs．Thuscausedermalcollagen，extracellularmatrixcomponentdegradation．Additionally,UVlightcausesthedepletionofcellularandenzymaticantioxidantsandactivatestheneuroendocrinesystemleadingtoimmunosuppressionandthereleaseofneuroendocrinemediators．Ultima

8、tely,these硕士学位论文maycontributetoskinphotoagingpresentation，Thuscausedermalcollagen，extracellularmatrixcomponentdegradation，fortheperformanceofthewrinkles，skinflabby,rough，decreasedelasticity,irregularpigmentchange．Skinphotoagingleadtoprematurel