Developmental changes in the neurotransmitter properties of dissociated sympathetic neurons: a cytochemical study of the effects of medium☆

摘要

Sympatheticprincipalneuronsweredissociatedfromthesuperiorcervicalgangliaofnewbornratsandgrowninseveralcultureconditionsshownpreviouslytoaffectthetransmitterstatusoftheneurons.Inthreeoftheseconditionstheneuronsareknowntodevelopadrenergicfunctionsovera3-to4-weekperiod;inafourthcondition,theydeveloppredominantlycholinergicfunctions.Inthisultrastructuralstudy,thetransmitterstatusoftheneuronsduringdevelopmentintheseveraldifferentmediawasexaminedafterpermanganatefixationwhichcausesagranularprecipitateinsynapticvesiclescontainingnorepinephrine(smallgranularvesiclesorSGV).Itwasfoundthatasearlyas4daysafterplating,synapsesandvaricositieswerepresent.Inallfourconditions,alloftheterminalscontainednumerousSGV,indicatingthattheneuronsbothsynthesizeandstorenorepinephrine.Undera€?adrenergica€?growthconditions,theterminalsremainedadrenergicinappearanceduringfurtherdevelopment.Undera€?cholinergica€?conditions,terminalsofcholinergicappearancewerepresentasearlyas7daysandtheirincidenceincreasedwithtime.Althoughthecholinergicterminalscontainedlittleornoendogenousnorepinephrine,manywereinitiallyabletotakeupandstoreexogenouscatecholamine.Theseresultsindicatethatthedissociatedsympatheticneuronsofnewbornratswhichsurviveincultureacquiredadrenergictransmitterfunctionsearly.Undera€?cholinergica€?cultureconditions,theneuronslosetheabilitytosynthesizedetectablequantitiesofnorepinephrine;theabilitytotakeupandstoredetectablequantitiesofexogenouscatecholaminesdisappearsmoreslowly.