Injury-induced class 3 semaphorin expression in the rat spinal cord

Exp Neurol. 2002 May;175(1):61-75. doi: 10.1006/exnr.2002.7884.


In this study we evaluate the expression of all members of the class 3 semaphorins and their receptor components following complete transection and contusion lesions of the adult rat spinal cord. Following both types of lesions the expression of all class 3 semaphorins is induced in fibroblast in the neural scar. The distribution of semaphorin-positive fibroblasts differs markedly in scars formed after transection or contusion lesion. In contusion lesions semaphorin expression is restricted to fibroblasts of the meningeal sheet surrounding the lesion, while after transection semaphorin-positive fibroblast penetrate deep into the center of the lesion. Two major descending spinal cord motor pathways, the cortico- and rubrospinal tract, continue to express receptor components for class 3 semaphorins following injury, rendering them potentially sensitive to scar-derived semaphorins. In line with this we observed that most descending spinal cord fibers were not able to penetrate the semaphorin positive portion of the neural scar formed at the lesion site. These results suggest that the full range of secreted semaphorins contributes to the inhibitory nature of the neural scar and thereby may inhibit successful regeneration in the injured spinal cord. Future studies will focus on the neutralization of class 3 semaphorins, in order to reveal whether this creates a more permissive environment for regeneration of injured spinal cord axons.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Axons / physiology
  • Carrier Proteins / biosynthesis
  • Carrier Proteins / genetics
  • Disease Models, Animal
  • Disease Progression
  • Fibroblasts / metabolism
  • Fibroblasts / pathology
  • Glycoproteins / biosynthesis*
  • Glycoproteins / genetics
  • In Situ Hybridization
  • Intercellular Signaling Peptides and Proteins
  • Male
  • Membrane Glycoproteins / biosynthesis
  • Membrane Glycoproteins / genetics
  • Nerve Regeneration
  • Nerve Tissue Proteins / biosynthesis*
  • Nerve Tissue Proteins / genetics
  • Neurons / metabolism
  • Neurons / pathology
  • Neuropilin-1
  • Pyramidal Tracts / injuries
  • Pyramidal Tracts / metabolism
  • Pyramidal Tracts / pathology
  • RNA, Messenger / biosynthesis
  • Rats
  • Rats, Wistar
  • Receptors, Cell Surface / biosynthesis
  • Receptors, Cell Surface / genetics
  • Red Nucleus / cytology
  • Red Nucleus / metabolism
  • Semaphorin-3A
  • Spinal Cord / pathology
  • Spinal Cord / physiopathology*
  • Spinal Cord Injuries / pathology
  • Spinal Cord Injuries / physiopathology*
  • Wounds, Nonpenetrating


  • Carrier Proteins
  • Glycoproteins
  • Intercellular Signaling Peptides and Proteins
  • Membrane Glycoproteins
  • Nerve Tissue Proteins
  • RNA, Messenger
  • Receptors, Cell Surface
  • Sema3a protein, rat
  • Semaphorin-3A
  • collapsin response mediator protein-2
  • Neuropilin-1