Growth associated protein 43 and neurofilament immunolabeling in the transected lumbar spinal cord of lizard indicates limited axonal regeneration

This study investigates the limited axonal regeneration in the spinal cord of lizards after injury. After transection of the lumbar spinal cord in lizards, a glial-connective tissue bridge that reconnects the rostral and caudal stumps of the interrupted spinal cord is formed at 11–34 days post-injury. Following an initial paralysis some recovery of hindlimb movements occurs within 1–3 months post-injury. The study uses immunohistochemical and ultrastructural analysis for a growth associated protein 43 (GAP-43) and neurofilament protein to observe axonal regeneration. The findings suggest that a limited axonal re-connection of the transected spinal cord occurs 1–3 months post-injury in lizards, contributing to the recovery of hind-limb movements after initial paralysis.

• 1
  Sparse GAP-43 positive axons are present in the proximal stump of the spinal cord but their number decreased in the bridge at 11–34 days post-transection.
• 2
  Few immunolabeled axons with a neurofilament protein of 200–220 kDa were seen in the bridge at 11–22 days post-transection but their number increased at 34 days and 3 months post-amputation in lizards that have recovered some hindlimb movements.
• 3
  Numerous neurons in the rostral and caudal stumps of the spinal cord were also labeled for GAP43, indicating that GAP-43 biosynthesis is related to axonal regeneration and sprouting from neurons that were damaged by the transection.