Electrical and Ca2+ signaling in dendritic spines of substantia nigra dopaminergic neurons

  1. Travis A Hage
  2. Yujie Sun
  3. Zayd M Khaliq  Is a corresponding author
  1. National Institutes of Health, United States

Abstract

Little is known about the density and function of dendritic spines on midbrain dopamine neurons, or the relative contribution of spine and shaft synapses to excitability. Using Ca2+ imaging, glutamate uncaging, fluorescence recovery after photobleaching and transgenic mice expressing labeled PSD-95, we comparatively analyzed electrical and Ca2+ signaling in spines and shaft synapses of dopamine neurons. Dendritic spines were present on dopaminergic neurons at low densities in live and fixed tissue. Uncaging-evoked potential amplitudes correlated inversely with spine length but positively with the presence of PSD-95. Spine Ca2+ signals were less sensitive to hyperpolarization than shaft synapses, suggesting amplification of spine head voltages. Lastly, activating spines during pacemaking, we observed an unexpected enhancement of spine Ca2+ midway throughout the spike cycle, likely involving recruitment of NMDA receptors and voltage-gated conductances. These results demonstrate functionality of spines in dopamine neurons and reveal a novel modulation of spine Ca2+ signaling during pacemaking.

Article and author information

Author details

  1. Travis A Hage

    Cellular Neurophysiology Unit, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, United States
    Competing interests
    The authors declare that no competing interests exist.
  2. Yujie Sun

    Cellular Neurophysiology Unit, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, United States
    Competing interests
    The authors declare that no competing interests exist.
  3. Zayd M Khaliq

    Cellular Neurophysiology Unit, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, United States
    For correspondence
    zayd.khaliq@nih.gov
    Competing interests
    The authors declare that no competing interests exist.

Ethics

Animal experimentation: This study was performed in strict accordance with the institutional guidelines recommended by the National Institutes of Health. All animals used were handled according to institutional animal care and use committee (IACUC) protocol ASP#1332 of NIH/NINDS.

Reviewing Editor

  1. Gary L Westbrook, Vollum Institute, United States

Publication history

  1. Received: December 18, 2015
  2. Accepted: May 9, 2016
  3. Accepted Manuscript published: May 10, 2016 (version 1)
  4. Version of Record published: June 9, 2016 (version 2)

Copyright

This is an open-access article, free of all copyright, and may be freely reproduced, distributed, transmitted, modified, built upon, or otherwise used by anyone for any lawful purpose. The work is made available under the Creative Commons CC0 public domain dedication.

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  1. Travis A Hage
  2. Yujie Sun
  3. Zayd M Khaliq
(2016)
Electrical and Ca2+ signaling in dendritic spines of substantia nigra dopaminergic neurons
eLife 5:e13905.
https://doi.org/10.7554/eLife.13905

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