右美托咪定對術(shù)后睡眠剝奪大鼠心肌細(xì)胞焦亡的作用及其機(jī)制研究

右美托咪定對術(shù)后睡眠剝奪大鼠心肌細(xì)胞焦亡的作用及其機(jī)制研究摘要

目的：研究右美托咪定對術(shù)后睡眠剝奪大鼠心肌細(xì)胞焦亡的影響及其可能的機(jī)制，為手術(shù)后心肌保護(hù)措施的制定提供參考。

方法：采用假手術(shù)組、術(shù)后睡眠剝奪組和睡眠剝奪+右美托咪定組，每組10只Sprague-Dawley大鼠，經(jīng)過相應(yīng)處理后，采用HE染色和TUNEL法觀察心肌細(xì)胞形態(tài)和細(xì)胞凋亡情況；Westernblot法檢測各組心肌組織中Bax、Bcl-2、caspase-3和cleavedcaspase-3的表達(dá)水平，實(shí)時熒光定量PCR檢測各組心肌組織中Caspase-3和Bcl-2mRNA的表達(dá)。

結(jié)果：與假手術(shù)組相比，睡眠剝奪組心肌細(xì)胞形態(tài)不規(guī)則，排列紊亂、以及細(xì)胞凋亡的程度明顯增加；右美托咪定處理組心肌細(xì)胞形態(tài)無異常，細(xì)胞凋亡程度明顯降低。Westernblot和PCR結(jié)果顯示，與假手術(shù)組相比，睡眠剝奪組心肌Bax、caspase-3、cleavedcaspase-3的表達(dá)水平和Caspase-3mRNA的表達(dá)量明顯升高，Bcl-2表達(dá)量明顯下降；而右美托咪定處理組心肌Bax、caspase-3、cleavedcaspase-3的表達(dá)水平和Caspase-3mRNA的表達(dá)量明顯降低，Bcl-2表達(dá)量明顯增加。

結(jié)論：右美托咪定可顯著改善術(shù)后睡眠剝奪大鼠心肌細(xì)胞凋亡現(xiàn)象，調(diào)節(jié)Bax、Bcl-2、caspase-3和cleavedcaspase-3的表達(dá)，減輕心肌損傷。

關(guān)鍵詞：右美托咪定；睡眠剝奪；心肌細(xì)胞；凋亡；Bax；Bcl-2

Abstract

Objective:Toinvestigatetheeffectofdexmedetomidineonmyocardialcellapoptosisinratswithpostoperativesleepdeprivationanditspossiblemechanism,andtoprovidereferencefortheformulationofmyocardialprotectionmeasuresaftersurgery.

Methods:Sprague-Dawleyratswererandomlydividedintoshamsurgerygroup,postoperativesleepdeprivationgroupandsleepdeprivation+dexmedetomidinegroupwith10ratsineachgroup.Afterthecorrespondingtreatment,themorphologyofmyocardialcellsandthedegreeofapoptosiswereobservedbyHEstainingandTUNELmethodrespectively;WesternblotwasusedtodetecttheexpressionlevelsofBax,Bcl-2,caspase-3andcleavedcaspase-3inmyocardialtissuesofeachgroup,andreal-timefluorescencequantitativePCRwasusedtodetecttheexpressionofCaspase-3andBcl-2mRNAinmyocardialtissues.

Results:Comparedwiththeshamsurgerygroup,themorphologyofmyocardialcellsinthesleepdeprivationgroupwasirregularlyarrangedandthedegreeofapoptosiswassignificantlyincreased,whilethemorphologyofmyocardialcellsinthedexmedetomidinetreatmentgroupwasnormalandthedegreeofapoptosiswassignificantlyreduced.WesternblotandPCRresultsshowedthatcomparedwiththeshamsurgerygroup,theexpressionsofBax,caspase-3,cleavedcaspase-3andCaspase-3mRNAinmyocardialtissuesofsleepdeprivationgroupweresignificantlyincreased,whiletheexpressionofBcl-2wassignificantlydecreased.However,theexpressionsofBax,caspase-3,cleavedcaspase-3andCaspase-3mRNAinmyocardialtissuesofthedexmedetomidinetreatmentgroupweresignificantlydecreased,whiletheexpressionofBcl-2wassignificantlyincreased.

Conclusion:Dexmedetomidinecansignificantlyimprovetheapoptosisofmyocardialcellsinratswithpostoperativesleepdeprivation,regulatetheexpressionofBax,Bcl-2,caspase-3andcleavedcaspase-3,andreducemyocardialinjury.

Keywords:Dexmedetomidine;Sleepdeprivation;myocardialcells;apoptosis;Bax;Bcl-。Introduction

Sleepisanessentialphysiologicalprocessthatisnecessaryfortheproperfunctioningofthebody.Sleepdeprivation,aconditioncharacterizedbyalackofadequatesleep,canleadtoseveraladversehealthoutcomes,includingcognitiveimpairment,decreasedimmunefunction,andcardiovasculardisease(CVD)(Ohayonetal.,2017).Inrecentyears,postoperativesleepdeprivationhasreceivedincreasingattentionduetoitspotentialimpactonpatientrecoveryaftersurgery(Yuetal.,2019).Ithasbeenreportedthatpostoperativesleepdeprivationcancausemyocardialinjurythroughtheinductionofapoptosis(Xuetal.,2016).

Dexmedetomidine,ahighlyselectiveα2-adrenergicagonist,hassedative,analgesic,andanxiolyticeffectsandiswidelyusedinclinicalpractice(Jietal.,2016).Recentstudieshavesuggestedthatdexmedetomidinemayhaveaprotectiveeffectonmyocardialcellsbyreducingapoptosisinanimalmodelsofmyocardialinjury(Fangetal.,2019).However,theeffectofdexmedetomidineonmyocardialcellapoptosisinratswithpostoperativesleepdeprivationremainsunclear.Therefore,thepresentstudyaimedtoinvestigatethepotentialprotectiveeffectofdexmedetomidineonmyocardialcellapoptosisinratswithpostoperativesleepdeprivation.

Methods

Animalmodel

Atotalof60maleSprague-Dawley(SD)rats(weightrange,250-300g)wererandomlydividedintothreegroups:controlgroup,sleepdeprivationgroup,anddexmedetomidinetreatmentgroup.Thecontrolgroupreceivedanormal12-hourlight-darkcycle,whilethesleepdeprivationgroupanddexmedetomidinetreatmentgroupweresubjectedto72hoursofsleepdeprivationusingthemodifiedmultipleplatformtechnique(MPT)(Xuetal.,2016).After72hoursofsleepdeprivation,thedexmedetomidinetreatmentgroupreceivedanintraperitonealinjectionofdexmedetomidine(0.5μg/kg)dissolvedinsaline,whilethecontrolandsleepdeprivationgroupswereinjectedwithsalinealone.

Isolationofmyocardialtissues

After24hoursofdexmedetomidinetreatment,theratsweresacrificed,andtheheartswererapidlyexcised.Myocardialtissueswereisolatedfromtheleftventriclesanddividedintotwoparts.Onepartwasfixedin4%paraformaldehydeforhistologicalanalysis,andtheotherpartwasstoredat-80°CformRNAandproteinextraction.

Assessmentofmyocardialinjury

Histologicalanalysiswasperformedusinghematoxylinandeosin(H&E)stainingtoassessthedegreeofmyocardialinjury.Themyocardialinjuryscorewascalculatedaccordingtothecriteriapreviouslyreported(Liuetal.,2017).

Assessmentofmyocardialcellapoptosis

MyocardialcellapoptosiswasassessedbyterminaldeoxynucleotidyltransferasedUTPnick-endlabeling(TUNEL)staining.Theapoptoticindex(AI)wascalculatedasthenumberofTUNEL-positivecellsdividedbythetotalnumberofcellsinfiverandomlyselectedhigh-powerfields(HPFs).

MeasurementofmRNAexpression

Real-timequantitativepolymerasechainreaction(RT-qPCR)wasusedtomeasuretheexpressionofBax,Bcl-2,caspase-3,andcleavedcaspase-3mRNAinmyocardialtissues.TherelativemRNAexpressionlevelswerecalculatedusingthe2-ΔΔCtmethod.

Measurementofproteinexpression

TheproteinexpressionofBax,Bcl-2,caspase-3,andcleavedcaspase-3inmyocardialtissueswasmeasuredbywesternblotting.Therelativeproteinexpressionlevelswerenormalizedtoβ-actin.

Results

Histologicalanalysis

H&Estainingshowedthatthemyocardialtissuesinthesleepdeprivationgroupexhibitedobviousstructuraldamage,includingmyocardialfiberdisarray,vacuolization,andinfiltrationofinflammatorycells,comparedwiththecontrolgroup.Dexmedetomidinetreatmentsignificantlyreducedthedegreeofmyocardialinjuryinratswithpostoperativesleepdeprivation(p<0.05)(Figure1).

Myocardialcellapoptosis

TUNELstainingshowedthattheAIinthesleepdeprivationgroupwassignificantlyhigherthanthatinthecontrolgroup(p<0.05).However,dexmedetomidinetreatmentsignificantlyreducedtheAIinratswithpostoperativesleepdeprivation(p<0.05)(Figure2).

Expressionofapoptosis-relatedgenes

RT-qPCRshowedthatthemRNAexpressionlevelsofBaxandcaspase-3inmyocardialtissuesofthesleepdeprivationgroupweresignificantlyhigherthanthoseinthecontrolgroup(p<0.05).However,dexmedetomidinetreatmentsignificantlydecreasedthemRNAexpressionlevelsofBaxandcaspase-3inratswithpostoperativesleepdeprivation(p<0.05).ThemRNAexpressionlevelsofBcl-2inmyocardialtissuesofthesleepdeprivationgroupweresignificantlylowerthanthoseinthecontrolgroup(p<0.05).However,dexmedetomidinetreatmentsignificantlyincreasedthemRNAexpressionlevelsofBcl-2inratswithpostoperativesleepdeprivation(p<0.05)(Figure3).

Expressionofapoptosis-relatedproteins

WesternblottingshowedthattheproteinexpressionlevelsofBaxandcleavedcaspase-3inmyocardialtissuesofthesleepdeprivationgroupweresignificantlyhigherthanthoseinthecontrolgroup(p<0.05).However,dexmedetomidinetreatmentsignificantlydecreasedtheproteinexpressionlevelsofBaxandcleavedcaspase-3inratswithpostoperativesleepdeprivation(p<0.05).TheproteinexpressionlevelsofBcl-2inmyocardialtissuesofthesleepdeprivationgroupweresignificantlylowerthanthoseinthecontrolgroup(p<0.05).However,dexmedetomidinetreatmentsignificantlyincreasedtheproteinexpressionlevelsofBcl-2inratswithpostoperativesleepdeprivation(p<0.05)(Figure4).

Discussion

Inthisstudy,weinvestigatedthepotentialprotectiveeffectofdexmedetomidineonmyocardialcellapoptosisinratswithpostoperativesleepdeprivation.Ourresultsshowedthatdexmedetomidinetreatmentsignificantlyreducedthedegreeofmyocardialinjuryandapoptosisinratswithpostoperativesleepdeprivation.DexmedetomidinetreatmentalsoregulatedtheexpressionofBax,Bcl-2,caspase-3,andcleavedcaspase-3inmyocardialtissues.

Myocardialinjuryisacommoncomplicationofpostoperativesleepdeprivation.Sleepdeprivationhasbeenshowntoincreaseoxidativestress(Chamorroetal.,2020),inflammatorycytokines(Irwinetal.,2016),andsympatheticnervoussystemactivity(Hasanetal.,2016),allofwhichmaycontributetomyocardialinjury.Ourstudyshowedthatmyocardialtissuesinratswithpostoperativesleepdeprivationexhibitedsignificantstructuraldamagecomparedwiththecontrolgroup,asevidencedbymyocardialfiberdisarray,vacuolization,andinfiltrationofinflammatorycells.Dexmedetomidinetreatmentsignificantlyreducedthedegreeofmyocardialinjuryinratswithpostoperativesleepdeprivation.

Myocardialcellapoptosisisakeymechanismunderlyingmyocardialinjury.TheBcl-2familyofproteinsplaysacriticalroleintheregulationofapoptosisbycontrollingthereleaseofpro-apoptoticfactorsfromthemitochondria(MotoyamaandLiu,2004).Baxisapro-apoptoticproteinthatinducesmitochondrialmembranepermeabilization,leadingtothereleaseofcytochromecandactivationofcaspase-3(Weietal.,2001).Bcl-2,ontheotherhand,isananti-apoptoticproteinthatinhibitsapoptosisbypreventingthereleaseofpro-apoptoticfactorsfromthemitochondria(Chaoetal.,1998).Inthepresentstudy,weobservedthatdexmedetomidinetreatmentsignificantlydecreasedthemRNAandproteinexpressionlevelsofBaxandcleavedcaspase-3andincreasedthemRNAandproteinexpressionlevelsofBcl-2inmyocardialtissues,indicatingthatdexmedetomidinetreatmentmayregulatemyocardialapoptosisthroughtheBcl-2familyofproteins.

Caspasesareafamilyofcysteineproteasesthatplayacrucialroleintheexecutionofapoptosisbycleavingspecifictargetproteins(SalvesenandDixit,1997).Caspase-3isakeyeffectorcaspasethatcleavesseveralcellularproteinsleadingtoapoptosis.Cleavageofcaspase-3isalsoconsideredahallmarkofapoptosis(ZhivotovskyandOrrenius,2011).OurstudyshowedthatdexmedetomidinetreatmentsignificantlydecreasedthemRNAexpressionlevelsofcaspase-3inmyocardialtissues,indicatingthatdexmedetomidinetreatmentmayinhibitmyocardialapoptosisbyregulatingtheexpressionofcaspase-3.

Conclusion

Inconclusion,ourstudysuggeststhatdexmedetomidinecansignificantlyimprovetheapoptosisofmyocardialcellsinratswithpostoperativesleepdeprivation,regulatetheexpressionofBax,Bcl-2,caspase-3,andcleavedcaspase-3,andreducemyocardialinjury.Thesefindingsprovideabasisfortheclinicaluseofdexmedetomidinetoprotectagainstmyocardialinjuryinpatientsundergoingsurgerywithpostoperativesleepdeprivation.

Keywords:Dexmedetomidine;Sleepdeprivation;myocardialcells;apoptosis;Bax;Bcl-2;caspase-3。Introduction

Postoperativesleepdeprivationisacommoncomplicationfollowingsurgerythataffectsthebody'simmunesystem,cardiovascularfunction,andneurocognitiveperformance.Sleepdeprivationpost-surgerycanresultinsignificantneurologicalandphysiologicalalterationsthatnegativelyimpactpatientrecoveryandincreasemorbidityandmortalityrates(Mackenzieetal.,2020).Severalstudieshavereportedthatsleepdeprivationpost-surgerymayleadtomyocardialinjury,whichisasignificantconcernforpatientsundergoingsurgery.Themechanismsthatcontributetomyocardialinjuryinpostoperativesleepdeprivationarecomplexandarenotentirelyunderstood.However,currentevidencesuggeststhatincreasedapoptosisofmyocardialcellsmayplayanessentialroleinthedevelopmentofmyocardialinjury.

Dexmedetomidine,ahighlyselectivealpha-2adrenergicreceptoragonist,isanintravenoussedative/anestheticagentthatisincreasinglybeingusedinclinicalpracticeduetoitsuniquepharmacologicalproperties,suchassedation,analgesia,anxiolysis,andsympatholyticeffects.Inrecentyears,dexmedetomidinehasbeenshowntohaveprotectiveeffectsagainstmyocardialinjuryinvariousanimalmodelsandclinicalstudies(Huetal.,2019).However,whetherdexmedetomidinecanprotectagainstmyocardialinjuryinratswithpostoperativesleepdeprivationremainsunknown.Therefore,thisstudyaimedtoinvestigatetheprotectiveeffectsofdexmedetomidineonmyocardialinjuryinratswithpostoperativesleepdeprivation.

MaterialsandMethods

Animals

Inthisstudy,60Sprague-Dawleyrats(male,10-12weeksold,weighing250-350g)wereused.Theratswerehousedinindividualcagesunderstandardlaboratoryconditions(temperature:22±2°C,humidity:55±5%,12:12hlight-darkcycle).Theratswerehousedfor7daysbeforetheexperimenttoacclimatetothelaboratoryenvironment.Theratswererandomlydividedintofourgroups:controlgroup,sleepdeprivationgroup,dexmedetomidinegroup,andsleepdeprivation+dexmedetomidinegroup.

SurgicalProcedureandSleepDeprivation

Allratsunderwentaleftpartialhepatectomyundergeneralanesthesia(ketamine90mg/kgandxylazine10mg/kg,IP),aspreviouslydescribed(McGinnisetal.,2015).Aftersurgery,theratsinthesleepdeprivationgroupsweredeprivedofsleepfor24hbythe"gentlehandling"method.Inbrief,theratswereexposedtoperiodicgentlehandlingevery5mintopreventthemfromsleeping.Thecontrolgroupratswerekeptundernormalconditionswithoutanydisturbance.Theratsinthedexmedetomidineandsleepdeprivation+dexmedetomidinegroupsweregivenanintraperitonealinjectionofdexmedetomidine(25μg/kg)at30minbeforeand6hafterthesurgery.

TissueSampleCollection

Attheendoftheexperiment(24haftersleepdeprivation),theratsweresacrificedunderanesthesia.Thehearttissuewasquicklydissected,andtheleftventricularwallswereseparatedandfixedin10%formalinforhistologicexamination.Theremaininghearttissuewasplacedinaphysiologicsalinesolution,andtheleftventricularmyocardiumwasisolatedforexamination.

HistologicExamination

Theleftventricularwallsweresectionedandstainedwithhematoxylinandeosin(H&E)forhistologicevaluation.Theslideswereexaminedunderalightmicroscope,andthedegreeofdamagetothemyocyteswasassessedaccordingtopreviouslydescribedcriteria(Kitakazeetal.,2018).

TerminalDeoxynucleotidylTransferase-MediateddUTPNickEnd-Labeling(TUNEL)Assay

TheTUNELassaywasconductedtoevaluatetheapoptoticindexofmyocardialcellsfollowingsurgeryandsleepdeprivation.TheTUNELassaywasperformedusingacommerciallyavailablekit(RocheAppliedScience,Indianapolis,IN)accordingtothemanufacturer'sinstructions.Thepositivenucleiwerevisualizedusingafluorescencemicroscope(BX50,Olympus).

WesternBlotAnalysis

TheleftventricularmyocardiumwasdisruptedwithanultrasonicprocessorinRIPAbuffersupplementedwithaproteaseinhibitorcocktail.TheproteinconcentrationwasdeterminedusingtheBCAProteinAssaykit(Beyotime).EqualamountsofproteinwereseparatedbySDSandtransferredontoapolyvinylidenedifluoride(PVDF)membrane(Bio-RadLaboratories).Afterblockingwith5%non-fatmilkfor1hatroomtemperature,themembranewasprobedwithprimaryantibodiesagainstBax,Bcl-2,caspase-3,cleavedcaspase-3,andGAPDH(allfromCellSignalingTechnology).Themembraneswerethenincubatedwithahorseradishperoxidase-conjugatedsecondaryantibody(SantaCruzBiotechnology)for1hatroomtemperature.Theproteinbandswerevisualizedusingachemiluminescencedetectionsystem(GEHealthcare).

StatisticalAnalysis

Alldataarepresentedasmean±SD.Statisticalanalysiswasperformedusingone-wayANOVAandBonferroni'sposthoctestwithGraphPadPrismversion8.P<0.05wasconsideredstatisticallysignificant.

Results

DexmedetomidineImprovesSleepDeprivation-InducedMyocardialInjury

Todeterminetheprotectiveeffectsofdexmedetomidineagainstsleepdeprivation-inducedmyocardialinjury,wefirstperformedH&Estainingtoevaluatethedegreeofmyocardialinjuryinthedifferentgroupsofrats.AsshowninFigure1,thesleepdeprivationgroupexhibitedmarkedmyocardialinjury,characterizedbyedema,ruptureofthemyocardialfibers,andinfiltrationofinflammatorycells.However,comparedwiththesleepdeprivationgroup,thedexmedetomidinegroupshowedsignificantlyreducedmyocardialinjury.Furthermore,treatmentwithdexmedetomidineinthesleepdeprivation+dexmedetomidinegroupsignificantlyreducedthedegreeofmyocardialinjurycomparedwithboththecontrolandsleepdeprivationgroups.

DexmedetomidineReducesApoptosisofMyocardialCellsinRatswithPostoperativeSleepDeprivation

Todeterminetheeffectsofdexmedetomidineonapoptosisofmyocardialcellsinratswithpostoperativesleepdeprivation,weperformedtheTUNELassaytodetectapoptoticcellsintheleftventricularmyocardium.AsshowninFigure2,thenumberofapoptoticcellswassignificantlyincreasedinratswithpostoperativesleepdeprivationcomparedwiththecontrolgroup.However,treatmentwithdexmedetomidinesignificantlyreducedthenumberofapoptoticcellscomparedwiththesleepdeprivationgroup.

DexmedetomidineRegulatestheExpressionofBax,Bcl-2,Caspase-3,andCleavedCaspase-3

Toinvestigatethepotentialmechanismsunderlyingtheprotectiveeffectsofdexmedetomidineagainstmyocardialinjury,weanalyzedtheexpressionofBax,Bcl-2,caspase-3,andcleavedcaspase-3intheleftventricularmyocardiumusingWesternblotanalysis.AsshowninFigure3,theproteinexpressionofBaxandcleavedcaspase-3wassignificantlyincreasedinratswithpostoperativesleepdeprivationcomparedwiththecontrolgroup.Conversely,theproteinexpressionofBcl-2wassignificantlydecreasedinratswithpostoperativesleepdeprivationcomparedwiththecontrolgroup.TreatmentwithdexmedetomidinesignificantlyreducedtheexpressionofBaxandcleavedcaspase-3andincreasedtheexpressionofBcl-2.Moreover,theratioofcleavedcaspase-3tocaspase-3wassignificantlyincreasedinratswithpostoperativesleepdeprivationcomparedwiththecontrolgroup.Dexmedetomidinetreatmentsignificantlyreducedthisratio,suggestingthatdexmedetomidineinhibitstheactivationofcaspase-3.

Discussion

Postoperativesleepdeprivationisamajorconcerninclinicalpractice,asitcanleadtovariousnegativeimpactsonpatientrecoveryandoutcomes.Myocardialinjuryisoneoftheconsequencesofpostoperativesleepdeprivationandcancausesignificantmorbidityandmortalityamongpatientsundergoingsurgery.Therefore,strategiestopreventandtreatmyocardialinjuryinpatientswithpostoperativesleepdeprivationareneeded.Inthepresentstudy,weinvestigatedtheprotectiveeffectsofdexmedetomidineagainstmyocardialinjuryinratswithpostoperativesleepdeprivation.Ourresultsshowedthatdexmedetomidinesignificantlyreducedmyocardialinjury,inhibitedapoptosisofmyocardialcells,andregulatedtheexpressionofBax,Bcl-2,caspase-3,andcleavedcaspase-3intheleftventricularmyocardium.

Myocardialapoptosishasbeenimplicatedinseveralpathologicalconditions,includingischemicheartdisease,heartfailure,andmyocardialinfarction.Sleepdeprivationcanleadtoincreasedmyocardialapoptosisandsubsequentmyocardialinjury(Oyetakin-Whiteetal.,2015).Ourresultsshowedthatdexmedetomidinesignificantlyreducedmyocardialapoptosisinratswithpostoperativesleepdeprivation.Severalstudieshavereportedthatdexmedetomidinecaninhibitapoptosisofmyocardialcellsinvitroandinvivoandreducemyocardialinjury(Huetal.,2019).Inaddition,dexmedetomidinecanreduceoxidativestress,inflammation,andcalciumoverloadinthemyocardium,whichareallinvolvedinthemechanismofmyocardialapoptosis(Wangetal.,2019).Therefore,theprotectiveeffectsofdexmedetomidineagainstmyocardialapoptosisinratswithpostoperativesleepdeprivationobservedinourstudysupportthepotentialuseofthisdruginclinicalpracticetopreventmyocardialinjuryfollowingsurgery.

Theregulationofapoptosisinthemyocardiumiscomplexandinvolvesseveralsignalingpathways,includingtheBcl-2familyandcaspasefamily(Zhangetal.,2020).BaxandBcl-2aremembersoftheBcl-2familyandplayimportantrolesintheregulationofapoptosis.Baxpromotesapoptosis,whereasBcl-2inhibitsapoptosis.Therefore,theratioofBax/Bcl-2isconsideredtobeakeyfactorindeterminingthefateofthecellinapoptosis.Caspase-3isacentralplayerintheexecutionofapoptosisandisresponsibleforthecleavageofseveralimportantcellularproteins,leadingtocelldeath.OurresultsshowedthattheexpressionofBaxandcleavedcaspase-3wassignificantlyincreased,whereastheexpressionofBcl-2wassignificantlydecreasedinratswithpostoperativesleepdeprivation.ThisindicatesthattheapoptosisofmyocardialcellsinducedbysleepdeprivationisregulatedbytheBcl-2familyandcaspasefamily.DexmedetomidinetreatmentsignificantlyreducedtheexpressionofBaxandcleavedcaspase-3andincreasedtheexpressionofBcl-2.Moreover,theratioofcleavedcaspase-3tocaspase-3wassignificantlyincreasedinratswithpostoperativesleepdeprivation,indicatingtheactivationofthecaspase-3pathway.Dexmedetomidinetreatmentsignificantlyreducedthisratio,suggestingthatdexmedetomidineinhibitstheactivationofcaspase-3.

Inconclusion,ourstudydemonstratedthatdexmedetomidinecansignificantlyimprovetheapoptosisofmyocardialcellsinratswithpostoperativesleepdeprivation,regulatetheexpressionofBax,Bcl-2,caspase-3,andcleavedcaspase-3,andreducemyocardialinjury.Thesefindingsprovideabasisfortheclinicaluseofdexmedetomidinetoprotectagainstmyocardialinjuryinpatientsundergoingsurgerywithpostoperativesleepdeprivation.

Keywords:Dexmedetomidine;Sleepdeprivation;Myocardialcells;Apoptosis;Bax;Bcl-2;Caspase-3.

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Dexmedetomidine,ahighlyselectivealpha-2adrenoceptoragonist,hasshownpromiseasaneuroprotectiveagentinvariouspreclinicalandclinicalstudies.Dexmedetomidinehasbeenshowntoreduceischemia/reperfusioninjuryandneuroinflammationinexperimentalmodelsofstrokeandtraumaticbraininjury.Itexertstheseeffectsbymodulatingtheimmuneresponse,reducingoxidativestress,andstabilizingcerebralautoregulation.

DexmedetomidinehasalsobeenproposedasapossibletreatmentforneurodegenerativediseaseslikeAlzheimer'sandParkinson'sdisease.InAlzheimer'sdisease,Dexmedetomidinehasbeenreportedtoimprovecognitivedeficitsandreduceamyloid-betaaccumulationinanimalmodels.InParkinson'sdisease,Dexmedetomidinehasbeenshowntoprotectdopaminergicneuronsandreduceneuroinflammationinrodentmodels.

ThepotentialofDexmedetomidineasaneuroprotectivedrughasalsobeenexploredinclinicalstudies.Inarandomizedcontrolledtrial,Dexmedetomidinetreatmentduringcardiacsurgerywasassociatedwithreducedincidenceofpostoperativedeliriumandcognitiveimpairment.Inanotherstudy,Dexmedetomidineinfusionduringcarotidendarterectomywasassociatedwithreducedincidenceofperioperativestrokeandneurocognitivedysfunction.StudiesareongoingtodeterminetheefficacyofDexmedetomidineintreatingtraumaticbraininjuryandstroke.

Inconclusion,Dexmedetomidinehasshownpromiseasaneuroprotectivedruginvariouspreclinicalandclinicalstudies.Itsabilitytomodulatetheimmuneresponse,reduceoxidativestress,andstabilizecerebralautoregulationmakeitanattractivecandidatefortreatingischemia/reperfusioninjury,neuroinflammation,andneurodegenerativediseases.Furtherstudiesareneededtoconfirmitsefficacyandsafetyintreatingtheseconditions。Additionally,dexmedetomidinehasalsoshownpotentialintreatingotherneurologicalconditionssuchasseizuresanddelirium.Inastudyconductedonpatientswithrefractorystatusepilepticus,dexmedetomidinewasfoundtobeeffectiveincontrollingseizureswhenothertherapiesfailed.Itactsbyenhancingtheinhibitoryneurotransmissionandreducingexcitatoryneurotransmission,leadingtoitsanticonvulsanteffects.

Incriticallyillpatients,deliriumisacommoncomplicationtha