ABSTRACT

YoungadultmaleSprague-Dawleyrats(aged10-12weeks)from CharlesRiverLaboratoriesweretrainedinasinglesessionofeight trialsinawatermazetofindasubmergedplatformlocatedinafixed position 12•Memoryforthelocationoftheplatformwastested24h laterusinga60-sfree-swimprobetrial.Inthefirstexperiment,rats receivedthreefootshocks{0.8mAfor1switha5-sintershock

a

interval)either2min,30minor4hbeforetheretentionprobetrial. Non-stressedcontrolsspentsignificantlymoretimeinthetarget quadrantthanintheoppositequadrant(P<0.01),indicating memoryforthelocationoftheplatform(Fig.Ia).Retentionwas impairedwhentheanimalsweretested30min(P<0.01},butnot 2minor4h,afterthefootshockstimulation.Figurelbshows representativeexamplesoftheswimmingpatternofanon-stressed controlandthatofaratgivenfootshockstimulation30minbefore testing.Controlratsdisplayedfocusedsearchingfortheplatformin thecorrectlocation,whereasstressedrats(30-mingroup}showed randomswimmingpatterns.Thefourgroupsdidnotdifferintotal pathlengthsduringtheprobetrial(F,,,.=0.04,P>0.98).These resultsindicatethatthestressimpairedspecificaspectsofspatial performanceandthattheretentionperformanceontheprobetrial wasnotaffectedbyanygrossdisturbancesinmotorperformance.