Endogenous descending modulation spatiotemporal effect of dynamic imbalance between descendingfacilitation and inhibition of nociception

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1、JPhysiol588.21(2010)pp417741884177Endogenousdescendingmodulation:spatiotemporaleffectofdynamicimbalancebetweendescendingfacilitationandinhibitionofnociceptionHao-JunYou1,2,JingLei1,3,Mei-YuSui1,2,LiHuang1,2,Yong-XiangTan1,2,ArneTjølsen4andLarsArendt-Nielsen31Cen

2、terforBiomedicalResearchonPain(CBRP),CollegeofMedicine,Xi’anJiaotongUniversity,Xi’an710061,P.R.China2DepartmentofPhysiology,CollegeofMedicine,Xi’anJiaotongUniversity,Xi’an710061,P.R.China3CenterforSensory–MotorInteraction(SMI),LaboratoryforExperimentalPainResear

3、ch,AalborgUniversity,FredrikBajersVej7D-3,DK-9220Aalborg,Denmark4DepartmentofBiomedicine,UniversityofBergen,N-5009Bergen,NorwayInconsciousrats,weinvestigatedthechangeofnociceptivepawwithdrawalreflexeselicitedbymechanicalandheatstimuliduringintramuscular(i.m.)5.8%

4、hypertonic(HT)salineelicitedmusclenociception.i.m.injectionofHTsalinecausedrapidonset,longlasting(around7days),bilateralmechanicalhyperalgesia,whileitinducedbilateral,sloweronset(1dayaftertheHTsalineinjection),long-term(about1–2weeks)heathypoalgesia.Ipsilateralt

5、opicalpre-treatmentofthesciaticnervewith1%capsaicinsignificantlypreventedtheoccurrenceofboththebilateralmechanicalhyperalgesiaandthecontralateralheathypoalgesia.Intrathecaladministrationofeither6-hydroxydopaminehydrobromide(6-OHDA)or5,7-dihydroxytryptamine(5,7-DH

6、T),andintraperitonealinjectionofnaloxoneallmarkedlyattenuatedtheHTsalineinducedbilateralheathypoalgesia,butnotthemechanicalhyperalgesia.Combinedwithexperimentswithlesioningoftherostroventralmedullawithkainicacid,thepresentdataindicatethatunilaterali.m.injectiono

7、fHTsalineelicitstime-dependentbilaterallong-termmechanicalhyperalgesiaandheathypoalgesia,whichweremodulatedbydescendingfacilitatoryandinhibitorycontrols,respectively.Wehypothesizethatsupraspinalstructuresmayfunctiontodiscriminatebetweenafferentnoxiousinputsmedia

8、tedbyAδ-andC-fibres,eitherfacilitatingAδ-fibremediatedresponsesorinhibitingC-fibremediatedactivities.However,thisdiscriminativefunctionisphysiologicallysilentorinactive,