fm1-43 and ethidium-homodimer

To investigate the in vivo role of glial cells in synaptic function, maintenance, and development, we have developed an approach to selectively ablate perisynaptic Schwann cells (PSCs), the glial cells at the neuromuscular junction (NMJ), en masse from live frog muscles. In adults, following acute PSC ablation, synaptic structure and function were not altered. However, 1 week after PSC ablation, presynaptic function decreased by approximately half, while postsynaptic function was unchanged. Retraction of nerve terminals increased over 10-fold at PSC-ablated NMJs. Furthermore, nerve-evoked muscle twitch tension was reduced. In tadpoles, repeated in vivo observations revealed that PSC processes lead nerve terminal growth. In the absence of PSCs, growth and addition of synapses was dramatically reduced, and existing synapses underwent widespread retraction. Our findings provide in vivo evidence that glial cells maintain presynaptic structure and function at adult synapses and are vital for the growth and stability of developing synapses.

Topics: Animals; Antibodies, Monoclonal; Benzimidazoles; Bungarotoxins; Cell Count; Complement System Proteins; Drug Combinations; Electric Stimulation; Estradiol; Ethidium; Excitatory Postsynaptic Potentials; Guinea Pigs; In Vitro Techniques; Microscopy, Electron; Models, Biological; Nerve Endings; Nerve Regeneration; Neural Conduction; Neural Inhibition; Neuroglia; Neuromuscular Junction; Norethindrone; Peanut Agglutinin; Presynaptic Terminals; Pyridinium Compounds; Quaternary Ammonium Compounds; Rana pipiens; Receptors, Cholinergic; Schwann Cells; Synapses; Synapsins; Synaptic Vesicles; Testosterone; Time Factors