| This study examined hindlimb stepping on different treadmill belt speeds in rats with an early
spinal cord transection. Rats received a low-thoracic spinal transection or sham operation on
postnatal day 1 (P1). On P5, subjects were tested on a treadmill for 30-min following an injection
of quipazine (a selective serotonin agonist). Spinal-transected rats showed significantly more
alternating hindlimb steps and total hindlimb movements, consistent with hindlimb
supersensitivity to serotonin following spinal injury. Spinal-transected and sham rats differently
adapted their intralimb coordination (i.e., hindlimb step cycle duration, step height, and step
length) in response to different treadmill speeds. Overall, findings from this study show that the
developing spinal cord is responsive to sensory feedback from treadmill stepping but suggest that
further experience with weight-bearing locomotion may be needed to express more adult-like
adaptations to differing belt speeds.
Keywords: spinal cord, development, alternating stepping, plasticity |