Sprouting capacity of lumbar motoneurons in normal and hemisected spinal cords of the rat

This study investigates the ability of motor neurons to sprout and compensate for muscle denervation after spinal cord injury in rats. The researchers examined how the level of muscle activity (normal vs. reduced by spinal cord hemisection) affects the capacity of motor neurons to sprout and reinnervate partially denervated muscles. The findings suggest that there is an upper limit to how much motor neurons can sprout, and this limit is the same regardless of whether the spinal cord is intact or hemisected.

• 1
  Enlargement of intact motor units (MUs) by sprouting was effective in compensating for up to 80% loss of innervation.
• 2
  There is a limit in MU size, whether or not the activity of the muscles was reduced by spinal cord hemisection.
• 3
  The upper limit of MU enlargement may be explained by the reinnervation of denervated muscle fibres by axon sprouts within the spatial territory of the muscle unit.