EphB3 receptor and ligand expression in the adult rat brain.

Eph receptors and ligands are two families of proteins that control axonal guidance during development. Their expression was originally thought to be developmentally regulated but recent work has shown that several EphA receptors are expressed postnatally. The EphB3 receptors are expressed during embryonic development in multiple regions of the central nervous system but their potential expression and functional role in the adult brain is unknown.

Upregulation of EphA3 receptor after spinal cord injury.

Spinal cord injury (SCI) releases a cascade of events that leads to the onset of an inhibitory milieu for axonal regeneration. Some of these changes result from the presence of repulsive factors that may restrict axonal outgrowth after trauma. The Eph receptor tyrosine kinase (RTK) family has emerged as a key repellent cue known to be involved in neurite outgrowth, synapse formation, and axonal pathfinding during development.

Transection of the adult rat spinal cord upregulates EphB3 receptor and ligand expression.

Eph receptors and ligands represent two families of proteins that control axonal guidance during development. Recent work has shown that several Eph receptors are expressed postnatally. Because the Eph molecules represent a class of axon guidance molecules that are mainly inhibitory to axonal growth, we investigated whether EphB3 expression was upregulated in both spinal cord and four supraspinal nuclei (locus coeruleus, vestibular, raphe pallidus, and red) 1 week after a complete spinal cord thoracic transection.

Upregulation of EphA receptor expression in the injured adult rat spinal cord.

After spinal cord injury (SCI), the inability of supraspinal neurons to regenerate or reform functional connections is likely due to proteins in the surrounding microenvironment restricting regeneration. EphAs are a family of receptor tyrosine kinases that are involved in axonal guidance during development. These receptors and their ligands, the Ephrins, act via repulsive mechanisms to guide growing axons towards their appropriate targets and allow for the correct developmental connections to be made.