Fluoro-Gold: A new retrograde axonal tracer with numerous unique properties

Department of Anatomy, School of Medicine, University of California, Irvine, CA 92717 U.S.A.
Brain Research (Impact Factor: 2.84). 08/1986; 377(1):147-54. DOI: 10.1016/0006-8993(86)91199-6
Source: PubMed


A new fluorescent dye, Fluoro-Gold, has been demonstrated to undergo retrograde axonal transport. Its properties include intense fluorescence, extensive filling of dendrites, high resistance to fading, no uptake by intact undamaged fibers of passage, no diffusion from labeled cells, consistent and pure commercial source, wide latitude of survival times and compatibility with all other tested neuro-histochemical techniques.

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    • "3.1.2. Fluoro-gold™ Fluoro-gold™ (FG, Fluorochrome, LLC; generic name: hydroxystilbamidine , OHSt) is a widely used neuronal tracer that shows persistent RGC labeling (Abdel-Majid et al., 2005; Berkelaar et al., 1994; Schmued and Fallon, 1986; Wessendorf, 1991). FG travels from the SC to RGC somata in rodents within a week and persists for several weeks allowing for reliable quantification of RGC density (Berkelaar et al., 1994; Salinas-Navarro et al., 2009a, 2009b). "
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    ABSTRACT: Glaucoma is a disease characterized by progressive axonal pathology and death of retinal ganglion cells (RGCs), which causes structural changes in the optic nerve head and irreversible vision loss. Several experimental models of glaucomatous optic neuropathy (GON) have been developed, primarily in non-human primates and, more recently and commonly, in rodents. These models provide important research tools to study the mechanisms underlying glaucomatous damage. Moreover, experimental GON provides the ability to quantify and monitor risk factors leading to RGC loss such as the level of intraocular pressure, axonal health and the RGC population. Using these experimental models we are able to gain a better understanding of GON, which allows for the development of potential neuroprotective strategies. Here we review the advantages and disadvantages of the relevant and most often utilized methods for evaluating axonal degeneration and RGC loss in GON. Axonal pathology in GON includes functional disruption of axonal transport (AT) and structural degeneration. Horseradish peroxidase (HRP), rhodamine-B-isothiocyanate (RITC) and cholera toxin-B (CTB) fluorescent conjugates have proven to be effective reporters of AT. Also, immunohistochemistry (IHC) for endogenous AT-associated proteins is often used as an indicator of AT function. Similarly, structural degeneration of axons in GON can be investigated via changes in the activity and expression of key axonal enzymes and structural proteins. Assessment of axonal degeneration can be measured by direct quantification of axons, qualitative grading, or a combination of both methods. RGC loss is the most frequently quantified variable in studies of experimental GON. Retrograde tracers can be used to quantify RGC populations in rodents via application to the superior colliculus (SC). In addition, in situ IHC for RGC-specific proteins is a common method of RGC quantification used in many studies. Recently, transgenic mouse models that express fluorescent proteins under the Thy-1 promoter have been examined for their potential to provide specific and selective labeling of RGCs for the study of GON. While these methods represent important advances in assessing the structural and functional integrity of RGCs, each has its advantages and disadvantages; together they provide an extensive toolbox for the study of GON. Copyright © 2015. Published by Elsevier Ltd.
    Experimental Eye Research 06/2015; DOI:10.1016/j.exer.2015.06.006 · 2.71 Impact Factor
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    • "In the visual system fluorogold (FG) has become the tracer of choice for many laboratories. This compound is actively and retrogradely transported from the axons to the RGC somas where it accumulates without leaking (Schmued and Fallon, 1986; Wessendorf, 1991; reviewed in Kobbert et al., 2000). Thus, 3 days after its application on the optic nerve stump, all the RGCs are traced (Nadal-Nicolas et al., 2012; Salinas-Navarro et al., 2009b, 2009c), while when applied onto both SCi approximately one week is needed to label 98.4% and 97.8% of the RGC population in albino and pigmented rats, respectively (Danias et al., 2002; Salinas- Navarro et al., 2009b, 2009c). "
    Experimental Eye Research 12/2014; 131. DOI:10.1016/j.exer.2014.12.005 · 2.71 Impact Factor
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    • "In our hands, FG has proven to be a robust retrograde tracer that produces intense labeling of the neuronal soma and processes, therefore allowing for easy identification of motor neurons (see Fig. 4). This tracer has a prolonged life within the neurons as well as high resistance to fading (Schmued and Fallon, 1986). However, leakage has been recently reported after intramuscular injections of FG in the mouse forelimb (Ba´cskai et al., 2013). "
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    ABSTRACT: Lower motor neuron dysfunction is one of the most debilitating neurological conditions and, as such, significantly impacts on the quality of life of affected individuals. Within the last decade, the engineering of mouse models of lower motor neuron diseases has facilitated the development of new therapeutic scenarios aimed at delaying or reversing the progression of these conditions. In this context, motor end plates (MEPs) are highly specialised regions on the skeletal musculature that offer minimally invasive access to the pre-synaptic nerve terminals, henceforth to the spinal cord motor neurons. Transgenic technologies can take advantage of the relationship between the MEP regions on the skeletal muscles and the corresponding motor neurons to shuttle therapeutic genes into specific compartments within the ventral horn of the spinal cord. The first aim of this neuroanatomical investigation was to map the details of the organisation of the MEP zones for the main muscles of the mouse hindlimb. The hindlimb was selected for the present work, as it is currently a common target to challenge the efficacy of therapies aimed at alleviating neuromuscular dysfunction. This MEP map was then used to guide series of intramuscular injections of Fluoro-Gold (FG) along the muscles' MEP zones, therefore revealing the distribution of the motor neurons that supply them. Targeting the entire MEP regions with FG increased the somatic availability of the retrograde tracer and, consequently, gave rise to FG-positive motor neurons that are organised into rostro-caudal columns spanning more spinal cord segments than previously reported. The results of this investigation will have positive implications for future studies involving the somatic delivery and retrograde transport of therapeutic transgenes into affected motor neurons. These data will also provide a framework for transgenic technologies aiming at maintaining the integrity of the neuromuscular junction for the treatment of lower motor neuron dysfunctions.
    Neuroscience 05/2014; 274. DOI:10.1016/j.neuroscience.2014.05.045 · 3.36 Impact Factor
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