In vivo imaging of axonal transport in murine motor and sensory neurons

BACKGROUND: Axonal transport is essential for neuronal function and survival. Defects in axonal transport have been identified as an early pathological feature in several disorders of the nervous system. The visualisation and quantitative analysis of axonal transport in vivo in rodent models of neurological disease is therefore crucial to improve our understanding of disease pathogenesis and for the identification of novel therapeutics. NEW METHOD: Here, we describe a method for the in vivo imaging of axonal transport of signalling endosomes in the sciatic nerve of live, anaesthetised mice. RESULTS: This method allows the multiparametric, quantitative analysis of in vivo axonal transport in motor and sensory neurons of adult mice in control conditions and during disease progression. COMPARISON WITH EXISTING METHODS: Previous in vivo imaging of the axonal transport of signalling endosomes has been limited to studies in nerve explant preparations or non-invasive approaches using magnetic resonance imaging; techniques that are hampered by major drawbacks such as tissue damage and low temporal and spatial resolution. This new method allows live imaging of the axonal transport of single endosomes in the sciatic nerve in situ and a more sensitive analysis of axonal transport kinetics than previous approaches. CONCLUSIONS: The method described in this paper allows an in-depth analysis of the characteristics of axonal transport in both motor and sensory neurons in vivo. It enables the detailed study of alterations in axonal transport in rodent models of neurological diseases and can be used to identify novel pharmacological modifiers of axonal transport.