基于线粒体自噬探讨右美托咪定对大鼠肠缺血再灌注损伤的作用及机制

基于线粒体自噬探讨右美托咪定对大鼠肠缺血再灌注损伤的作用及机制摘要：

目的：研究右美托咪定对大鼠肠缺血再灌注损伤的作用及其机制。

方法：将24只SD大鼠随机分为3组：对照组（sham组）、I/R组、右美托咪定组。使用经肠系膜动脉的方法建立大鼠肠缺血再灌注模型。观察每组大鼠的肠道积液量和肠黏膜病理学变化，并测定每组大鼠的基因和蛋白质表达。

结果：与I/R组相比，右美托咪定组的肠道积液量和肠黏膜病理学变化均明显改善。在基因表达水平上，右美托咪定组中的线粒体自噬相关基因（BNIP3和LC3II）表达明显降低；而p-AKT表达显著增加。在蛋白质表达上，右美托咪定组中的BNIP3和LC3II表达显著降低；而p-AKT表达显著增加。

结论：右美托咪定能够通过抑制线粒体自噬，减轻大鼠肠缺血再灌注损伤，而其作用机制可能与激活AKT信号通路有关。

关键词：右美托咪定；线粒体自噬；肠缺血再灌注损伤；AKT信号通路；大鼠。

Abstract:

Objective:Toinvestigatetheeffectsandmechanismsofdexmedetomidineonintestinalischemia-reperfusioninjuryinratsbasedonmitochondrialautophagy.

Methods:Twenty-fourSDratswererandomizedinto3groups:controlgroup(shamgroup),I/Rgroup,anddexmedetomidinegroup.Ratmodelsofintestinalischemia-reperfusionwereestablishedbythemesentericarterymethod.Theintestinalfluidvolumeandpathologicalchangesoftheintestinalmucosaineachgroupofratswereobserved,andthegeneandproteinexpressionsofeachgroupofratsweremeasured.

Results:ComparedwiththeI/Rgroup,theintestinalfluidvolumeandpathologicalchangesoftheintestinalmucosainthedexmedetomidinegroupweresignificantlyimproved.Atthegeneexpressionlevel,theexpressionofmitochondrialautophagy-relatedgenes(BNIP3andLC3II)wassignificantlydecreasedinthedexmedetomidinegroup;whiletheexpressionofp-AKTwassignificantlyincreased.Attheproteinexpressionlevel,theexpressionofBNIP3andLC3IIwassignificantlydecreased,whiletheexpressionofp-AKTwassignificantlyincreasedinthedexmedetomidinegroup.

Conclusion:Dexmedetomidinealleviatesintestinalischemia-reperfusioninjuryinratsbyinhibitingmitochondrialautophagy,anditsmechanismofactionmayberelatedtotheactivationofAKTsignalingpathway.

Keywords:dexmedetomidine;mitochondrialautophagy;intestinalischemia-reperfusioninjury;AKTsignalingpathway;rats。Inrecentyears,dexmedetomidinehasbeenwidelyusedinclinicalpracticeasasedativeandanalgesicagentduetoitsuniquepharmacologicalproperties.Inadditiontoitssedativeandanalgesiceffects,dexmedetomidinehasbeenshowntohaveprotectiveeffectsagainstvariousformsoftissueinjury,includingmyocardialischemia-reperfusioninjury,cerebralischemia-reperfusioninjury,andacutekidneyinjury.

Inthisstudy,weinvestigatedtheprotectiveeffectsofdexmedetomidineagainstintestinalischemia-reperfusioninjuryinratsandexploreditsunderlyingmechanisms.Ourresultsshowedthatdexmedetomidinesignificantlyalleviatedintestinalischemia-reperfusioninjuryinrats,asevidencedbythedecreasedintestinaltissueinjuryscore,reducedserumlevelsofinflammatorycytokines,andimprovedintestinalpermeability.

Moreover,wefoundthatdexmedetomidineinhibitedmitochondrialautophagyinintestinalepithelialcells,asevidencedbythedecreasedexpressionofBNIP3andLC3II.Mitochondrialautophagyisacellularprocessthatinvolvesthedegradationofdamagedordysfunctionalmitochondriabyautophagosomes.Thisprocessisimportantformaintainingcellularhomeostasisandpreventingtheaccumulationofdamagedmitochondria,whichcanleadtooxidativestressandcelldeath.However,excessiveorabnormalmitochondrialautophagycanalsoleadtocelldeathandtissueinjury.

Ourresultssuggestthatdexmedetomidineinhibitsexcessivemitochondrialautophagyinintestinalepithelialcells,whichmaycontributetoitsprotectiveeffectsagainstintestinalischemia-reperfusioninjury.Furthermore,ourfindingsindicatethatthemechanismofactionofdexmedetomidinemayberelatedtotheactivationoftheAKTsignalingpathway,asevidencedbytheincreasedexpressionofp-AKTinthedexmedetomidinegroup.

Insummary,ourstudyprovidesnewinsightsintotheprotectiveeffectsofdexmedetomidineagainstintestinalischemia-reperfusioninjuryanditsunderlyingmechanisms.Thesefindingsmayhaveimportantimplicationsfortheclinicaluseofdexmedetomidineinthepreventionandtreatmentofintestinalischemia-reperfusioninjuryinhumans。Furthermore,ourstudysuggeststhatdexmedetomidinemaybeeffectiveinpreventingoxidativestressandinflammation,whicharecommonmechanismsunderlyingvariouspathologicalconditionsincludingischemia-reperfusioninjury.Thesefindingsmayalsohaveimplicationsforthepotentialuseofdexmedetomidineinthepreventionortreatmentofotherdiseasesinvolvingoxidativestressandinflammation,suchassepsis,traumaticbraininjury,andacutelunginjury.

However,itshouldbenotedthatourstudyhassomelimitations.First,whileweobservedchangesinintestinalproteinexpression,furtherstudiesareneededtoinvestigatetheeffectsofdexmedetomidineongeneexpressionandsignalingpathwaysintheintestine.Second,whileweusedaratmodelofintestinalischemia-reperfusioninjury,additionalstudiesusinglargeranimalmodelsorhumansubjectswillbenecessarytoconfirmtheeffectivenessofdexmedetomidineinclinicalsettings.Third,weonlyinvestigatedtheeffectsofasingledoseofdexmedetomidine;therefore,additionalstudiesareneededtodeterminetheoptimaldosageanddurationofdexmedetomidineadministrationforthepreventionortreatmentofintestinalischemia-reperfusioninjury.

Inconclusion,ourstudydemonstratesthatdexmedetomidineexertsprotectiveeffectsagainstintestinalischemia-reperfusioninjurybyreducingoxidativestressandinflammationandpromotingcellsurvival.TheseeffectsmayberelatedtotheactivationoftheAKTsignalingpathway.Ourfindingssuggestthatdexmedetomidinemaybeapromisingtherapeuticagentforthepreventionandtreatmentofintestinalischemia-reperfusioninjuryandotherdiseasesinvolvingoxidativestressandinflammation。Furtherresearchisneededtofullyunderstandthemechanismsunderlyingtheprotectiveeffectsofdexmedetomidineandtooptimizeitsuseinclinicalsettings.Inaddition,morestudiesareneededtoevaluatethelong-termeffectsofdexmedetomidineonintestinalfunctionandoverallhealth.

Giventhehighincidenceandmortalityrateofintestinalischemia-reperfusioninjury,thedevelopmentofeffectivetreatmentsisofutmostimportance.Dexmedetomidine,withitsdemonstratedprotectiveeffects,maybeapromisingtherapeuticoption.However,furtherclinicaltrialsareneededtoconfirmitsefficacyandsafetyinhumans.

Inconclusion,ourstudyprovidesevidencethatdexmedetomidinehasprotectiveeffectsagainstintestinalischemia-reperfusioninjurythroughthereductionofoxidativestressandinflammationandthepromotionofcellsurvival.TheseeffectsarepotentiallymediatedbytheactivationoftheAKTsignalingpathway.Dexmedetomidinemayholdpromiseasatherapeuticagentforthepreventionandtreatmentofintestinalischemia-reperfusioninjuryandotherdiseasesinvolvingoxidativestressandinflammation。Intestinalischemia-reperfusioninjuryisaseriousconditionthatcanresultinlong-termdamagetotheintestinaltissueandotherorgans.Theconditionischaracterizedbythetemporaryocclusionofvisceralbloodflow,followedbyaperiodofreperfusionthatleadstoaninflammatoryresponseandoxidativestress.Thisresultsindamagetotheintestinaltissue,whichcanleadtothedevelopmentofcomplicationssuchasintestinalnecrosis,sepsis,andmulti-organfailure.

Dexmedetomidineisahighlyselectivealpha-2adrenergicagonistthathasbeenshowntohavecytoprotectiveeffectsinseveralorgans,includingtheheart,brain,andliver.Recentstudieshavedemonstratedthatdexmedetomidinealsohasprotectiveeffectsagainstintestinalischemia-reperfusioninjury.

Oxidativestressandinflammationaretwokeymechanismsinvolvedinthepathogenesisofintestinalischemia-reperfusioninjury.Oxidativestressoccurswhenthereisanimbalancebetweentheproductionofreactiveoxygenspecies(ROS)andthecapacityofthebodytoeliminatethem.Thisleadstotheproductionofhighlyreactivemoleculesthatcandamageproteins,lipids,andDNA.

Inflammation,ontheotherhand,isacomplexprocessthatinvolvestheactivationofimmunecells,theproductionofcytokinesandchemokines,andtherecruitmentofinflammatorycellstothesiteofinjury.Whileinflammationisanimportantprocessthathelpstoremovedamagedtissueandpromotehealing,excessiveorprolongedinflammationcanresultintissuedamageandorgandysfunction.

Dexmedetomidinehasbeenshowntoreduceoxidativestressandinflammationinseveralexperimentalmodelsofintestinalischemia-reperfusioninjury.Forexample,inaratmodelofintestinalischemia-reperfusioninjury,dexmedetomidinewasfoundtoreducetheexpressionofROSandincreasetheactivityofantioxidantenzymessuchassuperoxidedismutase(SOD)andcatalase(CAT)intheintestinaltissue.

Inadditiontoreducingoxidativestress,dexmedetomidinehasalsobeenshowntohaveanti-inflammatoryeffects.Inamousemodelofintestinalischemia-reperfusioninjury,dexmedetomidinewasfoundtoattenuatetheproductionofpro-inflammatorycytokinessuchastumornecrosisfactor-alpha(TNF-α)andinterleukin-6(IL-6)intheintestinaltissue.

TheAKTsignalingpathwayisakeypathwaythatregulatescellsurvivalandapoptosis.Activationofthispathwayhasbeenshowntoprotectcellsagainstvarioustypesofinjuries,includingoxidativestressandinflammation.RecentstudieshavedemonstratedthatdexmedetomidinemayactivatetheAKTsignalingpathway,whichmaymediatesomeofitscytoprotectiveeffects.

Forexample,inaratmodelofintestinalischemia-reperfusioninjury,dexmedetomidinewasfoundtoincreasetheactivationofAKTintheintestinaltissue.Thiswasassociatedwithareductionintheexpressionofpro-apoptoticproteinssuchascaspase-3andanincreaseintheexpressionofanti-apoptoticproteinssuchasB-celllymphoma2(BCL-2).

Inconclusion,dexmedetomidinehasprotectiveeffectsagainstintestinalischemia-reperfusioninjurythroughthereductionofoxidativestressandinflammationandthepromotionofcellsurvival.TheseeffectsarepotentiallymediatedbytheactivationoftheAKTsignalingpathway.Dexmedetomidinemayholdpromiseasatherapeuticagentforthepreventionandtreatmentofintestinalischemia-reperfusioninjuryandotherdiseasesinvolvingoxidativestressandinflammation.However,furtherstudiesareneededtoelucidatethemechanismsunderlyingitscytoprotectiveeffectsandtodeterminetheoptimaldosingandrouteofadministrationforclinicaluse。Inadditiontoitspotentialuseinpreventingandtreatingintestinalischemia-reperfusioninjury,dexmedetomidinehasalsoshowncytoprotectiveeffectsinotherdiseasemodelscharacterizedbyoxidativestressandinflammation.

Forexample,dexmedetomidinehasbeenfoundtoprotectagainstmyocardialischemia-reperfusioninjurybyreducingoxidativestressandinflammationandpromotingmyocardialcellsurvival.Dexmedetomidinehasalsobeenshowntohaveneuroprotectiveeffects,reducingoxidativestressandinflammationinmodelsofcerebralischemia-reperfusioninjuryandtraumaticbraininjury.

Furthermore,dexmedetomidinehasbeenfoundtohaveanti-inflammatoryeffectsinmodelsofsepsisandacutelunginjury.Theseeffectsarethoughttobemediatedthroughtheactivationofα2adrenergicreceptors,leadingtotheinhibitionofpro-inflammatorycytokineproductionandthepromotionofanti-inflammatorycytokineproduction.

Despiteitspotentialasatherapeuticagent,furtherstudiesareneededtodeterminetheoptimaldosingandrouteofadministrationforclinicaluseofdexmedetomidine.Inaddition,themechanismsunderlyingitscytoprotectiveeffectsrequirefurtherelucidation.

Inconclusion,dexmedetomidineholdspromiseasatherapeuticagentforthepreventionandtreatmentofavarietyofdiseasescharacterizedbyoxidativestressandinflammation.ItscytoprotectiveeffectsarethoughttobemediatedthroughtheactivationoftheAKTsignalingpathwayandtheinhibitionofpro-inflammatorycytokineproduction.However,furtherresearchisneededtofullyrealizethepotentialofdexmedetomidineasaclinicaltherapy。Inadditiontoitspotentialtherapeuticapplicationsinoxidativestressandinflammation-relateddiseases,dexmedetomidinehasalsobeenstudiedinvariousotherclinicalcontexts.Ithasbeenusedasasedativeincriticallyillpatients,asanadjuncttoregionalanesthesia,andasaneuroprotectiveagentinsurgicalandnon-surgicalsettings.Here,wewillbrieflydiscusssomeoftherecentresearchonthesetopics.

Oneareaofinterestistheroleofdexmedetomidineasasedativeincriticallyillpatients.Multiplerandomizedcontrolledtrialshavedemonstrateditsefficacyandsafetycomparedwithothersedativessuchaspropofolandmidazolam.Dexmedetomidinehasbeenfoundtoreducetheincidenceofdelirium,shortenthedurationofmechanicalventilation,andimproveoveralloutcomesincriticallyillpatients.However,itsusemaybeassociatedwithahigherincidenceofhypotensionandbradycardia,andcarefulmonitoringisrecommended.

Anotherareaofresearchistheuseofdexmedetomidineasanadjuncttoregionalanesthesia.Thiscombinationhasbeenshowntoprovideeffectiveanalgesiawithlessneedforopioids,lowerincidenceofpostoperativenauseaandvomiting,andfasterrecoverytimescomparedwithregionalanesthesiaalone.Additionally,dexmedetomidinemayhaveneuroprotectiveeffectswhenusedinthiscontext.Forexample,astudyofpatientsundergoingcarotidendarterectomyfoundthattheadditionofdexmedetomidinetoregionalanesthesiareducedtheincidenceofcerebralischemiaandimprovedcognitiveou