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.

摘要: Embryos immobilized with neuromuscular blocking agents for differing periods between 4.5 and 9 days of incubation had an increased number motoneurons in the brachial lumbar lateral motor columns. Treatment alpha-cobratoxin (alpha-CTX) on 4--9, instance, was able to prevent virtually all natural cell death during this period; control embryos average 22,500 day 5.5, 13,500 10, whereas treated approximately 21,000 cells 10. Curare, alpha-CTX, alpha-bungarotoxin (alpha-BTX) botulinum toxin were about equally effective preventing death. Similar treatment begun after 12, however, no effect number. If even a partial immobilization continued 10 (in totally earlier) most excess neurons maintained, some cases right up hatching, at which time died due respiratory failure. In contrast, when administration immobilizing stopped, allowing embryos' motility return levels, underwent delayed total fell below levels by 16--18. Limb muscles from exhibited relatively normal differentiation acetylcholinesterase (AChE) stained endplates innervated. Following curare two wing muscles, anterior posterior latissimus dorsi, found have AChE-stained endplates, only leg muscle examined quantitatively--the ischioflexorius (IFL)--did not; IFL, did, markedly reduced variance endplate distance, as well other apparent differences suggesting altered pattern innervation. Our findings imply that undergoing is closely related activity. Thus, functional interactions developing junction seem be critical controlling retrograde trophic factor involved its action somehow