Effects of treadmill training on noradrenaline fibers and the recovery of hindlimb motor function in rats after spinal cord contusion

Abstract

Objective To observe the effects of treadmill training on hindlimb motor recovery and noradrenaline (NA) fibers in rats with spinal cord contusion.Methods Spinal cord contusions at the T10 level were induced in 3-month old female SD rats by dropping a 10 g rod from a height of 25 mm.The injured rats were then randomly divided into a control group and a treadmill training group ( n =15 in each group).Treadmill training began 1 week post-injury.No treatment was administered to the control group rats.Hindlimb motor function was evaluated weekly from the 1 st to the 9th week post-injury using Basso Beattie Bresnahan (BBB) scores and average combined scores (ACOs).The expression of dopamine beta hydroxylase (DBH) in the spinal cord caudal to the injured area was detected by immunohistochemical staining.Results The treadmill training group exhibited significantly greater improvement in BBB scores from the 3rd week to the 7th week and in ACOs from the 2nd to the 9th week post-injury compared with the control group.The number of DBH positive fibers in the injured spinal cords and the number of DBH positive neurons in the injured frontal horns were also significantly higher in the training group.Conclusions Treadmill training can promote the recovery of hindlimb motor function in rats after spinal cord contusion,perhaps by increasing the number of DBH positive fibers and DBH positive neurons. Key words: Spinal cord contusion; Treadmill training; Noradrenaline