The influence of normal innervation upon abnormal synaptic connections between frog parasympathetic neurons☆
[摘要] Synapticconnectionsformbetweenparasympatheticneuronsinthefrogcardiacganglionwhentheirnormalpreganglionicinnervationisremoved.Thesynapsesbetweentheganglioncellsareinappropriateinthesensethattheyareabsentinnormallyinnervatedganglia.Thesenovelsynapsesformslowly;theyarereadilydetectedbyintracellularrecordingonlyafter1–2monthsofpreganglionicdenervation.After3monthsofextrinsicdenervationtwo-thirdsoftheganglioncellsreceivephysiologicallydetectablepostganglionicinputs,yettheefficacyofthesesynapsesremainssubstantiallylessthanthatofnative,preganglionicsynapses.Thisreductioninefficacyiscausedatleastinpartbythelocationofthepostganglionicsynapses;electronmicroscopyrevealsthemtobesituatedontheaxonsofganglioncells,whereaspreganglionicaxonsterminateprimarillyonthecellbodies.Theintrinsicsynapsesthatformintheabsenceofextrinsicinnervationarenolongerdetectablephysiologicallyafterganglioncellsarereinnervatedbypreganglionicaxons.Thissuppressionofconnectionsbetweenganglioncellsisnearlycomplete(90%)andisaconsequenceofcompetitionwithpreganglionicaxons:itdoesnotoccurintheabsenceofpreganglionicreinnervation.Thedataindicatethatthepresenceofpreganglionicinputstotheganglioncellsdiscouragestheformationandmaintenanceofsynapticconnectionsbetweenthem.
[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]
