Recovery of Locomotor Function in Adult Paraplegic Frogs by Inductive Lability in the Distal Isolated Spinal Cord Neural Networks

Abstract

We postulated (Krishnan, 1991) that in a spinal cord transected adult paraplegic mammal locomotor functions can be revived if polyneuronal innervation is reinduced in the paralyzed hind limb muscles. This procedure destabilizes the neural networks and induces new synaptic growth in the distal isolated cord. In this pilot project we tested the hypothesis in cord-transected adult paraplegic frogs. Polyneuronal innervation was reinduced by crushing the sciatic nerve in the right upper thigh. Left limb sciatic nerve was not crushed and served as control. Another group of adult frogs had only cord transection without nerve crush. Five to seven weeks postnerve crush, full powered flexion-extension movements in the hip and knee joints appeared in the right hind limb and were used for swimming and surface progression. Movements gradually declined over the next weeks, which in some animals was seen preserved even beyond 120 days. Paraplegic frogs without nerve crush did not show any recovery of locomotor function. Interestingly, the uncrushed contralateral limb also produced transient, weak locomotor-like movements. This lasted for 4 to 6 days and waned out completely thereafter. These results validate our hypothesis on methods to generate new synaptic sprouts and reconnections to redrive the locomotor system. We had recommended earlier that destabilization procedure should be included as an essential component in treatment strategies for spinal cord injury repair for effective relinking of the severed cord ends.

Key Words:

• Paraplegia
• Motor neuron
• Labile state
• Polyneuronal control
• Functional recovery
• Spinal cord regeneration