title: Mitochondrial Dynamics in Visual Cortex Are Limited In Vivo and Not Affected by Axonal Structural Plasticity.
abstract: Mitochondria buffer intracellular Ca2+and provide energy [1]. Because synaptic structures with high Ca2+buffering [2-4] or energy demand [5] are often localized far away from the soma, mitochondria are actively transported to these sites [6-11]. Also, the removal and degradation of mitochondria are tightly regulated [9, 12, 13], because dysfunctional mitochondria are a source of reactive oxygen species, which can damage the cell [14]. Deficits in mitochondrial trafficking have been proposed to contribute to the pathogenesis of Parkinson's disease, schizophrenia, amyotrophic lateral sclerosis, optic atrophy, and Alzheimer's disease [13, 15-19]. In neuronal cultures, about a third of mitochondria are motile, whereas the majority remains stationary for several days [8, 20]. Activity-dependent mechanisms cause mitochondria to stop at synaptic sites [7, 8, 20, 21], which affects synapse function and maintenance. Reducing mitochondrial content in dendrites decreases spine density [22, 23], whereas increasing mitochondrial content or activity increases it [7]. These bidirectional interactions between synaptic activity and mitochondrial trafficking suggest that mitochondria may regulate synaptic plasticity. Here we investigated the dynamics of mitochondria in relation to axonal boutons of neocortical pyramidal neurons for the first time in vivo. We find that under these circumstances practically all mitochondria are stationary, both during development and in adulthood. In adult visual cortex, mitochondria are preferentially localized at putative boutons, where they remain for several days. Retinal-lesion-induced cortical plasticity increases turnover of putative boutons but leaves mitochondrial turnover unaffected. We conclude that in visual cortex in vivo, mitochondria are less dynamic than in vitro, and that structural plasticity does not affect mitochondrial dynamics.
authors.affiliation: Department of Molecular Visual Plasticity, Netherlands Institute for Neuroscience, Royal Netherlands Academy of Arts and Sciences, Meibergdreef 47, 1105 BA Amsterdam, the Netherlands.
authors.forename: Laura
authors.initials: L
authors.lastname: Smit-Rigter
authors.affiliation: Department of Molecular Visual Plasticity, Netherlands Institute for Neuroscience, Royal Netherlands Academy of Arts and Sciences, Meibergdreef 47, 1105 BA Amsterdam, the Netherlands.
authors.forename: Rajeev
authors.initials: R
authors.lastname: Rajendran
authors.affiliation: Department of Synapse and Network Development, Netherlands Institute for Neuroscience, Royal Netherlands Academy of Arts and Sciences, Meibergdreef 47, 1105 BA Amsterdam, the Netherlands.
authors.forename: Catia A P
authors.initials: CA
authors.lastname: Silva
authors.affiliation: Department of Molecular Visual Plasticity, Netherlands Institute for Neuroscience, Royal Netherlands Academy of Arts and Sciences, Meibergdreef 47, 1105 BA Amsterdam, the Netherlands.
authors.forename: Liselot
authors.initials: L
authors.lastname: Spierenburg
authors.affiliation: Department of Synapse and Network Development, Netherlands Institute for Neuroscience, Royal Netherlands Academy of Arts and Sciences, Meibergdreef 47, 1105 BA Amsterdam, the Netherlands.
authors.forename: Femke
authors.initials: F
authors.lastname: Groeneweg
authors.affiliation: Department of Molecular Visual Plasticity, Netherlands Institute for Neuroscience, Royal Netherlands Academy of Arts and Sciences, Meibergdreef 47, 1105 BA Amsterdam, the Netherlands.
authors.forename: Emma M
authors.initials: EM
authors.lastname: Ruimschotel
authors.affiliation: Department of Molecular Visual Plasticity, Netherlands Institute for Neuroscience, Royal Netherlands Academy of Arts and Sciences, Meibergdreef 47, 1105 BA Amsterdam, the Netherlands.
authors.forename: Danielle
authors.initials: D
authors.lastname: van Versendaal
authors.affiliation: Department of Molecular Visual Plasticity, Netherlands Institute for Neuroscience, Royal Netherlands Academy of Arts and Sciences, Meibergdreef 47, 1105 BA Amsterdam, the Netherlands.
authors.forename: Chris
authors.initials: C
authors.lastname: van der Togt
authors.affiliation: Department of Neurophysiology, Faculty of Medicine, Ruhr University Bochum, Universitätsstrasse 150, 44801 Bochum, Germany.
authors.forename: Ulf T
authors.initials: UT
authors.lastname: Eysel
authors.affiliation: Department of Cortical Structure and Function, Netherlands Institute for Neuroscience, Royal Netherlands Academy of Arts and Sciences, Meibergdreef 47, 1105 BA Amsterdam, the Netherlands.
authors.forename: J Alexander
authors.initials: JA
authors.lastname: Heimel
authors.affiliation: Department of Synapse and Network Development, Netherlands Institute for Neuroscience, Royal Netherlands Academy of Arts and Sciences, Meibergdreef 47, 1105 BA Amsterdam, the Netherlands.
authors.forename: Christian
authors.initials: C
authors.lastname: Lohmann
authors.affiliation: Department of Molecular Visual Plasticity, Netherlands Institute for Neuroscience, Royal Netherlands Academy of Arts and Sciences, Meibergdreef 47, 1105 BA Amsterdam, the Netherlands; Department of Molecular and Cellular Neurobiology, Center for Neurogenomics and Cognitive Research, VU University Amsterdam, de Boelelaan 1085, 1081 HV, the Netherlands. Electronic address: c.levelt@nin.knaw.nl.
authors.forename: Christiaan N
authors.initials: CN
authors.lastname: Levelt
mesh_terms: D000818:Animals; D005260:Female; D051379:Mice; D008810:Mice, Inbred C57BL; D063154:Mitochondrial Dynamics; D009473:Neuronal Plasticity; D017729:Presynaptic Terminals / Q000502:physiology*; D017966:Pyramidal Cells / Q000502:physiology*; D014793:Visual Cortex / Q000502:physiology*