Membrane cholesterol regulates different modes of synaptic vesicle release and retrieval at the frog neuromuscular junction

Authors

  • Hermann A. Rodrigues,

    1. Departamento de Morfologia, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brasil
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  • Ricardo F. Lima,

    1. Departamento de Fisiologia e Biofísica, Universidade Federal de Minas Gerais, Belo Horizonte, Brasil
    Current affiliation:
    1. Departamento de Fisiologia e Farmacologia, Centro de Ciências da Saúde, Universidade Federal do Ceará, Fortaleza, Brasil
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  • Matheus de C. Fonseca,

    1. Departamento de Morfologia, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brasil
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  • Ernani A. Amaral,

    1. Departamento de Morfologia, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brasil
    Current affiliation:
    1. Instituto de Ciências e Tecnologia, Universidade Federal dos Vales do Jequitinhonha e Mucuri, Diamantina, Brasil
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  • Patrícia M. Martinelli,

    1. Departamento de Morfologia, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brasil
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  • Lígia A. Naves,

    1. Departamento de Fisiologia e Biofísica, Universidade Federal de Minas Gerais, Belo Horizonte, Brasil
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  • Marcus V. Gomez,

    1. Núcleo Santa Casa de Pós-Graduação, Universidade Federal de Minas Gerais, Belo Horizonte, Brasil
    2. INCT Molecular Medicine, Universidade Federal de Minas Gerais, Belo Horizonte, Brasil
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  • Christopher Kushmerick,

    1. Departamento de Fisiologia e Biofísica, Universidade Federal de Minas Gerais, Belo Horizonte, Brasil
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  • Marco A. M. Prado,

    1. Robarts Research Institute and Department of Physiology and Pharmacology and Anatomy & Cell Biology, University of Western Ontario, London, ON, Canada
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  • Cristina Guatimosim

    Corresponding author
    • Departamento de Morfologia, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brasil
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Correspondence: Dr C. Guatimosim, as above.

E-mail: cguati@icb.ufmg.br

Abstract

We investigated the effects of cholesterol removal on spontaneous and KCl-evoked synaptic vesicle recycling at the frog neuromuscular junction. Cholesterol removal by methyl-β-cyclodextrin (MβCD) induced an increase in the frequency of miniature end-plate potentials (MEPPs) and spontaneous destaining of synaptic vesicles labeled with the styryl dye FM1-43. Treatment with MβCD also increased the size of MEPPs without causing significant changes in nicotinic receptor clustering. At the ultrastructural level, synaptic vesicles from nerve terminals treated with MβCD were larger than those from control. In addition, treatment with MβCD reduced the fusion of synaptic vesicles that are mobilized during KCl-evoked stimulation, but induced recycling of those vesicles that fuse spontaneously. We therefore suggest that MβCD might favor the release of vesicles that belong to a pool that is different from that involved in the KCl-evoked release. These results reveal fundamental differences in the synaptic vesicle cycle for spontaneous and evoked release, and suggest that deregulation of cholesterol affects synaptic vesicle biogenesis and increases transmitter packing.

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