Nonacceptance of innervation by innervated neonatal rat muscle☆
[摘要] Denervatedadultmuscleacceptsinnervationandhashighlevelsofextrajunctionalacetylcholine(ACh)receptor,comparedtoinnervatedadultmuscle.Ifthehighreceptordensityoranyexternallyorientedpartofthereceptormoleculepermittedortriggeredfunctionalsynaptogenesis,theninnervatedneonatalmuscle,withitsknownhighextrajunctionalsensitivity,shouldalsoacceptextrasynapsesfromimplantedmotornerves.Thispredictionwastestedbyimplantingthecommonperonealnerveintoinnervatedlateralgastrocnemiusmusclein25neonatalratsandstudyingtheinnervationachieved1–8weekslater.Withoneexception,zeroornegligibletwitchtensionswereobtainedwhentheimplantednervewasstimulated.Intracellularrecordingintwocasesshowednoevidenceofsubthresholdevokedpotentialsinsurfacemusclefibers.Incontrast,whentheoriginalmotornervewascutatthetimeofcommonperonealnerveimplantation,reinnervationoccurredassoonas4dayslater,andsubstantialindirecttwitches(mostobservedqualitatively)wereinvariablyfound6–7daysafteroperation.Fourtoeightweeksafternerveimplantationintodenervatedmuscle,substantialtwitchtensionswereobtaineduponstimulationoftheimplantednerve.α-BungarotoxinbindingtoextrajunctionalAChreceptorsperunitsurfaceareawassimilarininnervatedneonatalanddenervatedadultmuscle.Therefore,nonacceptanceofadditionalfunctionalinnervationinneonatalmuscleimpliesthatahighaveragedensityofextrajunctionalAChreceptorisnotsufficienttopermitortriggerfunctionalneuromuscularjunctionformation.
[发布日期] [发布机构]
[效力级别] [学科分类] 生物科学（综合）
[关键词] [时效性]
