title: In vivo imaging of axonal transport of mitochondria in the diseased and aged mammalian CNS.
abstract: The lack of intravital imaging of axonal transport of mitochondria in the mammalian CNS precludes characterization of the dynamics of axonal transport of mitochondria in the diseased and aged mammalian CNS. Glaucoma, the most common neurodegenerative eye disease, is characterized by axon degeneration and the death of retinal ganglion cells (RGCs) and by an age-related increase in incidence. RGC death is hypothesized to result from disturbances in axonal transport and in mitochondrial function. Here we report minimally invasive intravital multiphoton imaging of anesthetized mouse RGCs through the sclera that provides sequential time-lapse images of mitochondria transported in a single axon with submicrometer resolution. Unlike findings from explants, we show that the axonal transport of mitochondria is highly dynamic in the mammalian CNS in vivo under physiological conditions. Furthermore, in the early stage of glaucoma modeled in adult (4-mo-old) mice, the number of transported mitochondria decreases before RGC death, although transport does not shorten. However, with increasing age up to 23-25 mo, mitochondrial transport (duration, distance, and duty cycle) shortens. In axons, mitochondria-free regions increase and lengths of transported mitochondria decrease with aging, although totally organized transport patterns are preserved in old (23- to 25-mo-old) mice. Moreover, axonal transport of mitochondria is more vulnerable to glaucomatous insults in old mice than in adult mice. These mitochondrial changes with aging may underlie the age-related increase in glaucoma incidence. Our method is useful for characterizing the dynamics of axonal transport of mitochondria and may be applied to other submicrometer structures in the diseased and aged mammalian CNS in vivo.
authors.affiliation: Department of Ophthalmology, Faculty of Medical Science, University of Fukui, Fukui 910-1193, Japan; Department of Ophthalmology, Faculty of Life Sciences, Kumamoto University, Kumamoto 860-8556, Japan;
authors.forename: Yuji
authors.initials: Y
authors.lastname: Takihara
authors.affiliation: Department of Ophthalmology, Faculty of Medical Science, University of Fukui, Fukui 910-1193, Japan; Department of Ophthalmology, Faculty of Life Sciences, Kumamoto University, Kumamoto 860-8556, Japan; inatani@u-fukui.ac.jp.
authors.forename: Masaru
authors.initials: M
authors.lastname: Inatani
authors.affiliation: Division of Homeostatic Development, Department of Developmental Physiology, National Institute for Physiological Sciences, Aichi 444-8585, Japan; Department of Physiological Sciences, SOKENDAI (The Graduate University for Advanced Studies), Aichi 444-8585, Japan;
authors.forename: Kei
authors.initials: K
authors.lastname: Eto
authors.affiliation: Department of Ophthalmology, Faculty of Life Sciences, Kumamoto University, Kumamoto 860-8556, Japan;
authors.forename: Toshihiro
authors.initials: T
authors.lastname: Inoue
authors.affiliation: Shiley Eye Institute, University of California, San Diego, La Jolla, CA 92093;
authors.forename: Alexander
authors.initials: A
authors.lastname: Kreymerman
authors.affiliation: Department of Ophthalmology, Faculty of Medical Science, University of Fukui, Fukui 910-1193, Japan;
authors.forename: Seiji
authors.initials: S
authors.lastname: Miyake
authors.affiliation: Department of Ophthalmology, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan;
authors.forename: Shinji
authors.initials: S
authors.lastname: Ueno
authors.affiliation: Department of Ophthalmology, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan;
authors.forename: Masatoshi
authors.initials: M
authors.lastname: Nagaya
authors.affiliation: Department of Ophthalmology, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan;
authors.forename: Ayami
authors.initials: A
authors.lastname: Nakanishi
authors.affiliation: Department of Ophthalmology, Faculty of Life Sciences, Kumamoto University, Kumamoto 860-8556, Japan;
authors.forename: Keiichiro
authors.identifier: http://orcid.org/0000-0002-4102-9374
authors.initials: K
authors.lastname: Iwao
authors.affiliation: Department of Ophthalmology, Faculty of Medical Science, University of Fukui, Fukui 910-1193, Japan;
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Takamura
authors.affiliation: Ushimado Marine Institute, Graduate School of Natural Science and Technology, Okayama University, Okayama 701-4303, Japan;
authors.forename: Hirotaka
authors.initials: H
authors.lastname: Sakamoto
authors.affiliation: Ushimado Marine Institute, Graduate School of Natural Science and Technology, Okayama University, Okayama 701-4303, Japan;
authors.forename: Keita
authors.initials: K
authors.lastname: Satoh
authors.affiliation: Department of Ophthalmology, Mie University Graduate School of Medicine, Mie 514-8507, Japan.
authors.forename: Mineo
authors.initials: M
authors.lastname: Kondo
authors.affiliation: Ushimado Marine Institute, Graduate School of Natural Science and Technology, Okayama University, Okayama 701-4303, Japan;
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Sakamoto
authors.affiliation: Shiley Eye Institute, University of California, San Diego, La Jolla, CA 92093;
authors.forename: Jeffrey L
authors.initials: JL
authors.lastname: Goldberg
authors.affiliation: Division of Homeostatic Development, Department of Developmental Physiology, National Institute for Physiological Sciences, Aichi 444-8585, Japan; Department of Physiological Sciences, SOKENDAI (The Graduate University for Advanced Studies), Aichi 444-8585, Japan;
authors.forename: Junichi
authors.initials: J
authors.lastname: Nabekura
authors.affiliation: Department of Ophthalmology, Faculty of Life Sciences, Kumamoto University, Kumamoto 860-8556, Japan;
authors.forename: Hidenobu
authors.initials: H
authors.lastname: Tanihara
mesh_terms: D000375:Aging; D000818:Animals; D001370:Axonal Transport / Q000502:physiology*; D001369:Axons / Q000502:physiology; D001692:Biological Transport; D002490:Central Nervous System / Q000473:pathology* / Q000502:physiology*; D004195:Disease Models, Animal; D005260:Female; D005901:Glaucoma / Q000473:pathology / Q000503:physiopathology; D021621:Imaging, Three-Dimensional; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D008928:Mitochondria / Q000502:physiology*; D009900:Optic Nerve / Q000473:pathology; D017785:Photons; D012160:Retina / Q000166:cytology; D012165:Retinal Ganglion Cells / Q000502:physiology*; D012590:Sclera / Q000503:physiopathology; D013997:Time Factors
keywords: aging; in vivo imaging; mammalian CNS; mitochondrial axonal transport; neurodegeneration