Neurotrophic factor and Trk signaling mechanisms underlying the promotion of motor recovery after acute spinal cord injury in rats

Neurotrophic factor (NF) and Trk signaling mechanisms underlying the promotion of motor recovery following acute spinal cord injury (SCI) in rats were investigated. Thirty-six adult Sprague-Dawley rats of both genders were randomly divided into three groups: Sham-operated, model, and NF/Trk. Each group consisted of 12 rats, with four subgroups in each group: 1, 3, 5 and 7 days. Sham-operated rats received a laminectomy without SCI, while in model group rats, SCI was induced using an improved version of the Allen's method. After analepsia, sham-operated and model group rats were given normal saline via gavage, while the NF/Trk group received NFs and Trk. Lower limb function was measured using the Basso, Beattie and Bresnahan scale 1, 3, 5 and 7 days before and after surgery. Results were analyzed statistically. Six rats from each group were randomly selected for sacrifice at 1, 3, 5 and 7 days after the operation. Morphological changes in motor neurons in the anterior gray column were observed by hematoxylin and eosin, and Nissl staining. Brain-derived expression of NF (BNDF) and neurotrophin-3 (NT-3) was detected by immunofluorescence, and the number of positive cells was counted. Expression of Trk B and Trk protein C receptor was measured by western blotting. In the NF/Trk group, the expression of NF/Trk pathway components remarkably increased. In addition, the morphology of motor neurons in the anterior gray column was improved. Expression of BNDF and NT-3 was significantly increased in motor neurons of the anterior gray column in NF/Trk rats compared with those of sham-operated and model rats (P<0.05). NFs promote motor recovery following acute SCI in rats and may have valuable clinical applications.