L-type calcium channels in the photoreceptor ribbon synapse: Localization and role in plasticity

Michele Nachman-Clewner, Robert St. Jules, Ellen Townes-Anderson

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114 Scopus citations


Calcium (Ca2+) influx through voltage-gated Ca2+ channels stimulates a variety of neural activities, including process outgrowth, neurotransmission, and synaptic plasticity. In general, L-type channels control Ca2+ influx into the soma and dendrites, whereas other Ca2+ channel types control presynaptic activities. Neurons that make ribbon synapses, however, are among a select group of nerve cells whose presynaptic Ca2+-dependent secretion is linked to L-type channels. Recently, photoreceptor ribbon synapses have been shown to be capable of dramatic structural remodeling and neuritic outgrowth. Here, we have examined 1) the distribution of dihydropyridine (DHP)-sensitive (L-type) Ca2+ channels in photoreceptor presynaptic structures and 2) the role of these channels in axonal plasticity and process outgrowth in culture. Using anti-alpha(1C) and the fluorescent dihydropyridine, (-)-DM-BODIPY DHP, L-type channels were localized in the outer plexiform layer of retinal sections and in presynaptic terminals of freshly isolated photoreceptors. In the rod terminal, dense patches of label were present; their distribution and number matched that of synaptic ribbons. After 1-7 days in vitro, punctate alpha(1C) staining occurred along newly formed neurites and presynaptic varicosities. Functional channels were present throughout the culture period, as determined by fura-2 imaging. Channel blockage by nicardipine, a DHP antagonist, inhibited axonal remodeling. Specifically, it prevented axon retraction and lamellipodium formation, reduced neurite growth, and produced long, thin processes on some, primarily cone, photoreceptors. L-type Ca2+ channel activity, therefore, not only stimulates neurotransmission but contributes to presynaptic structural plasticity at the ribbon synapse.

Original languageEnglish (US)
Pages (from-to)1-16
Number of pages16
JournalJournal of Comparative Neurology
Issue number1
StatePublished - Dec 6 1999

All Science Journal Classification (ASJC) codes

  • Neuroscience(all)


  • Axons
  • Neurites
  • Presynaptic terminals
  • Regeneration
  • Retina


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