2011-04-18【进展】【Nature】胰岛素样生长因子II在记忆巩固与增强中发挥了重要作用

Figure 1A:Northern blot analysis showed that, compared to controls that were exposed to the box without foot shock and either euthanized immediately after (0 h2) or at paired time points (no shock, 2), the hippocampal expression of IGF-II mRNA did not change at 6 and 9 h but increased significantly at 20 h and had a strong trend towards an increase at 36 h after trainingFigure 1B:Quantitative PCR with reverse transcription (qRT–PCR) analyses of mRNA extracts confirmed the significant increase of IGF-II mRNA 20 h after training compared to no-shock and 0 h2 controls whereas, in the sameextracts, IGF-I mRNA remained unchanged Figure 1C:showed that hippocampal levels of IGF-II protein significantly increased at 20, but not at 72 or 96 h after training, compared to both time-matched unpaired and 0 h2 controls 结论：IA training leads to an increase in IGF-II that temporally overlaps that of C/EBPbFigure 1D:方法：hippocampal bilateral injection of C/EBPb antisense oligodeoxynucleotide (b-ODN)结果：compared to control scrambled ODN (SC-ODN), b-ODN completely disrupted the training-induced IGF-II increase without changing the IGF-II expression in unpaired control rats 24 h after training

ChromatinimmunoprecipitationofhippocampalextractsconfirmedthatC/EBPbbindsinvivotoaC/EBPbconsensussequenceinthepromoterregionoftheratIGF-IIexon1(SupplementaryFig.4).

方法：BilateralinjectionsofIGF-IIODNantisense(IGF-II-ODN)wereusedtoselectivelyknockdowntheIGF-IIexpressioninthedorsalhippocampus.Figure2A:Injectioneitherimmediatelyor8haftertraining,oratbothtimepoints,showedthatdouble,butnotsingle,injectionsofIGF-II-ODNsignificantlydisruptedmemoryretentionat24haftertraining,comparedtoSC-ODNIGF-II-ODNdoublyinjectedat24and32haftertraining,comparedtoSC-ODN,significantlydisruptedmemoryretentionat48haftertraining(Fig.2a)andre-trainingoftheamnesicratsresultedinnormalmemoryretention24hafterre-training(Fig.2a),thusexcludinghippocampaldamageornon-specificeffects.However,IGF-II-ODNdoublyinjectedat96and104haftertrainingdidnotaffectmemoryretention24hlater(Fig.2a).Figure2B:TheamnesiacausedbyIGF-II-ODNdoubleinjectionswasrescuedbytheco-admiNISTrationofrecombinantIGF-II,butnotIGF-I(Fig.2b),furtherprovingthatIGF-IIexpressionisessentialforIAmemoryconsolidation.

问题：whetherexogenouslyadmiNISTeredIGF-IIintothehippocampusimmediatelyaftertrainingmodulatesmemorystrength.Figure3A:Thelatencycut-offtimewasraisedto900s.BilateralinjectionsofIGF-IIimmediatelyaftertrainingsignificantlyandpersistentlyenhancedmemoryretentionat24hand7days,comparedtoIGF-IorvehicleFigure3B:Finally,hippocampalinjectionofIGF-IIimmediatelyaftertrainingsignificantlyenhancedmemoryretentiontested3weekslaterwhenthelatencyofvehicle-injectedratswasnotsignificantlydifferentfromacquisition,indicatingthatIGF-IIpreventsforgetting

TheIGF-II-mediatedmemoryenhancementwasdose-dependent(SupplementaryFig.8):hippocampalinjectionsof25or2.5ng,like250ng,immediatelyaftertrainingincrementallyenhancedmemoryretentionat24h.

Figure3C:TheIGF-IIeffectgeneralizedtoanothermemorytask,contextualfearconditioning.BilateralhippocampalinjectionofIGF-IIimmediatelyaftercontextual-auditoryfearconditioningtrainingsignificantlyenhancedcontextualfearconditioningretention24hlater,withoutaffectingauditoryfearconditioningtested48haftertrainingFigure3D:Finally,becauseIAconsolidationalsocriticallyinvolvestheamygdala（杏仁核）,wetestedtheeffectofbilateraIGF-IIinjectionsintotheamygdalaimmediatelyaftertraining,butfoundnoeffectattesting24hlater

Figure4A:BilateralhippocampalinjectionofIGF-II24haftertraininghadnoeffectonmemoryretentiontestedat48hHowever,if24haftertrainingIGF-IIwasgivenaftermemoryretrieval(Test1),memoryretentionwassignificantlyenhanced24hlaterFigure4B:BilateralhippocampalinjectionofIGF-IIimmediatelyafterretrieval(Test1),2weeksaftertraining,didnotchangememoryretentiontested1daylater,comparedtovehicle

Figure5A:SpecificinhibitorsofIGF-IIR(anti-IGF-IIRantibody)butnotIGF-IR(JB1)co-injectedwithIGF-IIcompletelyabolishedthememoryenhancementcomparedtorespectivecontrols(Fig.5a).Theinhibitorsalonedidnotaffectmemoryretention(Fig.5a).Figure5B:Similarlytotheantisenseexperiments,comparedtocontrolIgG,asinglebilateralhippocampalinjectionofanti-IGF-IIRantibodyimmediatelyaftertrainingdidnotaffectmemoryretention(Fig.5a),whereasdoubleinjections,immediatelyand8haftertraining,causedacompleteamnesia24haftertraining

问题：whetherIGF-II-mediatedmemoryenhancementrecruitsnewproteinsynthesis.Figure5C:Bilateralhippocampalco-injectionofIGF-IIandtheproteinsynthesisinhibitoranisomycinimmediatelyafterTest1,24haftertraining,showedthatanisomycin,comparedtovehicle,completelydisruptedtheIGF-II-mediatedmemoryenhancementtested24hlater(Fig.5c)withoutchangingthetraining-inducedretentionlevels.

Figure6A:QuantitativewesternblotanalysesconfirmedthattrainingsignificantlyincreasedbothpCREBandC/EBPblevelsinthehippocampus20hlater14(trained-vehiclevsnaive-vehicle,Fig.6a).Comparedtovehicle,IGF-IItreatmentimmediatelyaftertrainingresultedinonlyatendencytowardsafurtherincreaseinbothMarkers(Fig.6a).Figure6B:

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