Role of Axon Guidance Molecules in Ascending and Descending Paths in Spinal Cord Regeneration

Abstract

Axon guidance molecules (AGM) are critical regulators of neural development and play a vital role in guiding axons to their target regions during spinal cord development. The correct wiring of neural circuits depends on these molecules' precise expression and function. Defects in axonal pathfinding, growth cone navigation, axonal branching, and synapse formation have far-reaching implications for neuronal circuit construction and function after CNS traumas, such as spinal cord injury (SCI), which affect the expression or activity of AGM. Ascending and descending paths in the spinal cord have been found to include many AGM, including Netrins, Slits, Semaphorins (Sema), Ephrins, and their receptors. In contrast to the repulsive signals like Slits and Semaphorins, which restrict axonal growth and guide axons away from unsuitable locations, Netrins are appealing guidance cues that encourage axonal growth and guidance. Defects in motor function and sensory processing can result from changes in the expression or activity of Ephrins or their receptors, which play an essential role in axonal guidance and synaptic plasticity in the spinal cord. Herein, we highlighted the expressions, functions, and mechanisms of AGM in ascending and descending spinal cord tracts, which can help us identify novel therapeutic targets to improve axonal regeneration and functional recovery after SCI.

Keywords: Ascending and Descending tracts; Axon guidance molecules; Corticospinal tract; Spinal cord injury.