Mild hypothermia effects on matrix metalloproteinase-9 expression in the perihematomal region of rats following experimental intracerebral hemorrhage

BACKGROUND:Matrixmetalloproteinase-9(MMP-9)expressionincreaseswithintracerebralhemorrhage,andparticipatesinthepathophysiologicalprocessesofsecondarybraininjuryafterintracerebralhemorrhage.OBJECTIVE:ToinvestigatetheeffectsofmildhypothermiaonMMP-9expressionandbrainedemaintheperihematomalregionofexperimentalintracerebralhemorrhagerats.DESIGN,TIMEANDSETTING:Therandomized,controlledexperimentwasperformedattheCentralLaboratoryofShandongProvincialHospitalbetweenMayandSeptember2007.MATERIALS:Seventy-two,Wistar,malerats,12-weeksold,wereusedforthisstudy.Rabbitanti-MMP-9primaryantibodywaspurchasedfromBoster,China.METHODS:Wistarratswereequallyandrandomlydividedintonormothermiaandmildhypothermiagroups.Thetwogroupseachcomprisedcontrol,6-hourintracerebralhemorrhage,24-hourintracerebralhemorrhage,48-hourintracerebralhemorrhage,72-hourintracerebralhemorrhage,and1-weekintracerebralhemorrhagesubgroups,withsixratsineachsubgroup.Ratmodelsofintracerebralhemorrhagewereestablishedbyinjecting100μLofautologousbloodintotheratcaudatenucleus.Ratsinthemildhypothermiagroupreceivedfourhoursoflocalmildhypothermiaimmediatelyfollowingtheinjection.Intracerebraltemperaturewasmaintainedat(33±0.5)℃.Subsequently,intracerebraltemperaturewasspontaneouslyrecoveredat25℃.Ratsinthecontrolsubgroupwerenotinjectedwithautologousbloodandreceivedonlywithintracerebralhemorrhage.MAINOUTCOMEMEASURES:BrainwatercontentandMMP-9expressionsurroundingthehematomaregion.RESULTS:MMP-9expressionincreasedat6hours,andbrainedemareachedapeakat48hoursafterintracerebralhemorrhage.MMP-9expressionwassignificantlydecreasedinthemildhypothermiagroupcomparedwiththenormothermiagroupateachtimepoint(P<0.05).CONCLUSION:MildhypothermiacansignificantlyinhibitMMP-9overexpressionandrelievebrainedemafollowingintracerebralhemo