Document Detail

Cell death of motoneurons in the chick embryo spinal cord. IV. Evidence that a functional neuromuscular interaction is involved in the regulation of naturally occurring cell death and the stabilization of synapses.
MedLine Citation:
PMID:  489787     Owner:  NLM     Status:  MEDLINE    
Embryos immobilized with neuromuscular blocking agents for differing periods between 4.5 and 9 days of incubation had an increased number of motoneurons in the brachial and lumbar lateral motor columns. Treatment with alpha-cobratoxin (alpha-CTX) on days 4--9, for instance, was able to prevent virtually all natural cell death during this period; control embryos had an average of 22,500 lumbar motoneurons on day 5.5, and 13,500 on day 10, whereas treated embryos had approximately 21,000 cells on day 10. Curare, alpha-CTX, alpha-bungarotoxin (alpha-BTX) and botulinum toxin were all about equally effective in preventing cell death. Similar treatment begun after day 12, however, had no effect on cell number. If even a partial immobilization was continued after day 10 (in embryos totally immobilized earlier) most of the excess neurons were maintained, in some cases right up to hatching, at which time the embryos died due to respiratory failure. In contrast, when administration of the immobilizing agents was stopped, allowing the embryos' motility to return to control levels, the excess neurons underwent a delayed cell death and total cell number fell to below control levels by days 16--18. Limb muscles from embryos with excess motoneurons exhibited relatively normal differentiation and had acetylcholinesterase (AChE) stained endplates which were innervated. Following curare treatment the two wing muscles, anterior and posterior latissimus dorsi, were found to have an increased number of AChE-stained endplates, whereas the only leg muscle examined quantitatively--the ischioflexorius (IFL)--did not; the IFL, did, however, have a markedly reduced variance in endplate distance, as well as other apparent differences suggesting an altered pattern of innervation. Our findings imply that the number of motoneurons undergoing natural cell death is closely related to muscle activity. Thus, functional interactions at the developing neuromuscular junction seem to be critical in controlling cell death. If a retrograde trophic factor is involved its action is somehow related to muscle activity.
R Pittman; R W Oppenheim
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Publication Detail:
Type:  Comparative Study; Journal Article    
Journal Detail:
Title:  The Journal of comparative neurology     Volume:  187     ISSN:  0021-9967     ISO Abbreviation:  J. Comp. Neurol.     Publication Date:  1979 Sep 
Date Detail:
Created Date:  1979-12-20     Completed Date:  1979-12-20     Revised Date:  2007-11-15    
Medline Journal Info:
Nlm Unique ID:  0406041     Medline TA:  J Comp Neurol     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  425-46     Citation Subset:  IM    
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MeSH Terms
Acetylcholinesterase / metabolism
Bungarotoxins / pharmacology
Cell Count
Cell Survival / drug effects
Chick Embryo
Cobra Neurotoxin Proteins / pharmacology
Motor Endplate / enzymology
Motor Neurons / physiology*
Neuromuscular Junction / physiology*
Spinal Cord / cytology,  embryology*
Tubocurarine / pharmacology
Reg. No./Substance:
0/Bungarotoxins; 0/Cobra Neurotoxin Proteins; 57-95-4/Tubocurarine; EC

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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