Remodeling of an identified motoneuron during metamorphosis: central and peripheral actions of ecdysteroids during regression of dendrites and motor terminals.
During metamorphosis of the moth Manduca sexta, an identified leg motoneuron, the femoral depressor motoneuron (FeDe MN), undergoes reorganization of its central and peripheral processes. This remodeling is under the control of two insect hormones: the ecdysteroids and juvenile hormone (JH). Here, we asked whether peripheral or central actions of the ecdysteroids influenced specific regressive aspects of MN remodeling. We used stable hormonal mimics to manipulate the hormonal environment of either the FeDe muscle or the FeDe MN soma. Our results demonstrate that motor-terminal retraction and dendritic regression can be experimentally uncoupled, indicating that central actions of ecdysteroids trigger dendritic regression whereas peripheral actions trigger terminal retraction. Our results further demonstrate that discrete aspects of motor-terminal retraction can also be experimentally uncoupled, suggesting that they also are regulated differently.
Knittel
Laura M
LM
Department of Biological Structure and Function, School of Dentistry, Oregon Health & Science University, 611 S.W. Campus Drive, Portland, Oregon 97201, USA.
Kent
Karla S
KS
D000818:Animals; D002450:Cell Communication / Q000502:physiology; D003712:Dendrites / Q000502:physiology*; D004441:Ecdysterone / Q000494:pharmacology*; D017952:Ganglia, Invertebrate / Q000166:cytology / Q000254:growth & development; D007605:Juvenile Hormones / Q000494:pharmacology; D007814:Larva / Q000166:cytology; D018402:Manduca / Q000166:cytology* / Q000254:growth & development; D008675:Metamorphosis, Biological / Q000187:drug effects / Q000502:physiology*; D009045:Motor Endplate / Q000502:physiology; D009046:Motor Neurons / Q000187:drug effects / Q000502:physiology / Q000648:ultrastructure*; D009132:Muscles / Q000294:innervation; D009469:Neuromuscular Junction / Q000502:physiology; D017729:Presynaptic Terminals / Q000502:physiology
D007605:Juvenile Hormones; D004441:Ecdysterone