Objective:Tostudytheeffectofelectroacupuncture(EA)andVerapamilandNifedipine(calciumchannelinhibitors)onfreecalciumconcentrationsofcellsandintrasynaptosomesinhypothalamus(HT),periaqueductualgreymatter(PAG)andhippocampus(HIP)ofmice.Methods:ThefemaleICRmicewererandomlypidedintocontrol,EA,CaCl2andCaCl2+EAgroups(n=8ineachgroup).Painthresholdwasdetectedbyusingradiation-heatirradiation-inducedtailflickmethod.EA(8Hz,asuitablestimulatingstrength,dense-sparsewavesanddurationof30min)wasappliedto'Shuigou'(水沟GV26)and'Chengjiang'(承浆CV24).CaCl2(10μL,0.2μmol/L)wasinjectedintothelateralcerebralventricleofmiceafterEA.Theconcentrationsofcytosolicfreecalcium([Ca2+]i)inHIP,PAG,HTcellsuspensionspecimenandhippocampalintrasynaptosomesuspensionofmiceweredeterminedbythefluorescentcalciumindicatorFura-2-AMandaspectrofluorometer.Results:DuringEAanalgesia,theintracellularfree[Ca2+]iinHTandPAGspecimensandintrsynaptosomal[Ca2+]iofthe3cerebralregionsdecreasedconsiderably(P<0.05～0.01),butthatinhippocampalcellsuspensionincreasedsignificantly(P<0.01)incomparisonwithcontrolgroup.Theconcentrationsofhippocampalintrasynaptosomalfree[Ca2+]idecreasedsignificantlyafteraddingVerapamilandNifedipinetotheextractedhippocampalintrasynaptosomalspecimen.MicroinjectionofCaCl2intolateralventriclehadnoapparentinfluenceondegreeofanalgesia(DA)%andintracellularandintrasynapsotomal[Ca2+]i,butsignificantlylowerDA%andreducechangesofcytosolicandintrasynaptosomal[Ca2+]iinducedbyEAstimulation.Conclusion:CalciumionintheneuronsandintrasynaptosomeofHT,PAGandHIPisinvolvedinelectroacupunctureanalgesia.
