Understanding the axonal response to injury by in vivo imaging in the mouse spinal cord: A tale of two branches

Exp Neurol. 2019 Aug:318:277-285. doi: 10.1016/j.expneurol.2019.04.008. Epub 2019 Apr 12.

Abstract

Understanding the basic properties of how axons respond to injury in the mammalian central nervous system (CNS) is of fundamental value for developing strategies to promote neural repair. Axons possess complex morphologies with stereotypical branching patterns. However, current knowledge of the axonal response to injury gives little consideration to axonal branches, nor do strategies to promote axon regeneration. This article reviews evidence from in vivo spinal cord imaging that axonal branches markedly impact the degenerative and regenerative responses to injury. At a major bifurcation point, depending on whether one or both axonal branches are injured, neurons may choose either a more self-preservative response or a more dynamic response. The stabilizing effect of the spared branch may underlie a well-known divergence in neuronal responses to injury, and illustrates an example where in vivo spinal cord imaging reveals insights that are difficult to elucidate with conventional histological methods.

Keywords: 2-photon microscopy; Axon degeneration; Axon regeneration; Axonal branches; Bifurcation; In vivo imaging; Neuronal responses to axonal injury; Spinal cord.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.
  • Review

MeSH terms

  • Animals
  • Axons / pathology*
  • Mice
  • Nerve Regeneration / physiology
  • Neuroimaging / methods*
  • Optical Imaging / methods*
  • Spinal Cord Injuries / pathology*