title: Basic techniques for long distance axon tracing in the spinal cord.
abstract: The regeneration of axons after a spinal cord injury or disease is attracting a significant amount of interest among researchers. Being able to assess these axons in terms of morphology, length and origin is essential to our understanding of the regeneration process. Recently, two specific axon tracers have gained much recognition; biotinylated dextran amine (BDA) 10 kDa as an anterograde tracer and cholera toxin-B as a retrograde tracer. However, there are still several complexities when using these tracers, including the volume that should be administered and the best administration site so that a significant amount of axons are labeled in the area of interest. In this article, we describe some simple procedures for injecting the tracers and detecting them. We also quantified the number of axons at different locations of the spinal cord. Our results show axons labeled from motor cortex injections traveled down to the lumbosacral spinal cord in 2 weeks, while BDA injections into the lateral vestibular nucleus and reticular formation took 3 weeks to label axons in the lumbosacral spinal cord. Moreover, this protocol outlines some basic procedures that could be used in any laboratory and gives insight into the number of axons labeled and how procedures could be tailored to meet specific researcher's needs.
authors.affiliation: Department of Neurological Surgery, University of Wisconsin, Madison, Wisconsin, 53792; Department of Biomedical Engineering, University of Wisconsin, Madison, Wisconsin, 53706.
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Hellenbrand
authors.forename: Katie E
authors.initials: KE
authors.lastname: Kaeppler
authors.forename: Euhaa
authors.initials: E
authors.lastname: Hwang
authors.forename: Mark E
authors.initials: ME
authors.lastname: Ehlers
authors.forename: Ross D
authors.initials: RD
authors.lastname: Toigo
authors.forename: Joseph D
authors.initials: JD
authors.lastname: Giesler
authors.forename: Erika R
authors.initials: ER
authors.lastname: Vassar-Olsen
authors.forename: Amgad
authors.initials: A
authors.lastname: Hanna
mesh_terms: D000818:Animals; D001369:Axons / Q000187:drug effects*; D001710:Biotin / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000494:pharmacology; D001933:Brain Stem / Q000187:drug effects; D002772:Cholera Toxin / Q000008:administration & dosage / Q000494:pharmacology*; D003911:Dextrans / Q000008:administration & dosage / Q000494:pharmacology*; D008297:Male; D008856:Microscopy, Fluorescence; D009044:Motor Cortex / Q000187:drug effects; D009416:Nerve Regeneration / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D012584:Sciatic Nerve / Q000187:drug effects; D013116:Spinal Cord / Q000187:drug effects; D013119:Spinal Cord Injuries; D013194:Staining and Labeling / Q000379:methods*
chemical_list: D003911:Dextrans; C076397:biotinylated dextran amine; D001710:Biotin; D002772:Cholera Toxin
keywords: anterograde; axon tracer; biotinylated dextran amine; cholera toxin-B; retrograde