The Study Of Rehabilitative Training Repair In Hemi-transected Spinal Cord Injury

[Objective]: To establish the animal modle of rehabilitative training to repair hemi-transected spinal cord injury, we would observed the change on somato-sensory evoked potential,BBB grading mark and the expression of BDNF in ventral horn at different period of time after hemi-transecting spinal cord injury in SD rat. So as to know the relation between rehabilitative training, BDNF and the plasticity of spinal cord as well as to study how rehabilitative training promoting plasticity of spinal cord. [Materials and Methods]: 66 healthy adult srague-daweley rats (female), weight l90-210g, were divided into 11 groups at random including normal group; control groups (hemi-transecting spinal cord injury 2 weeks group, 4weeks group,6 weeks group, 8 weeks group and 10 weeks group) and training groups (rehabilitative training for 2 weeks group, 4weeks group,6 weeks p, 8 weeks group and 10 weeks group) .6 rats were used in every group. Hemi-transected spinal cord at T₁₂ segment of rats.3^ed day after operation, these rats were loosely restrained in plastic tubes and rehabilitative trained 30min/day,5day/week for 2-10 weeks (I have set up a practical and reliable motor training model of rats). Simultaneously,examining somato-sensory evoked potential every week and BBB gradeing.Then these animals were sacrificed via a way that infused 4% formaldehydum polymerisatum fluid into aorta with aortic cannulation. And fixed the spinal cord segments (caudally to the T₁₂ spinal cord segments) taken out from the rats with 4% formaldehydum polymerisatum (4℃), toput them into 30% sucrose-PBS overnight. These tissues were made into frozen section in 20[im thickness,take out one section every two. Then anti-BDNF serum were applied with the immunohistochemical ABC method to detect the distribution and expression of BDNF in spinal gray matter of rats at different period time after SCI with Olympus microscope. All data were analyzed by one-way anova, SNK-q test and paired-t test.[Result]: 1. Before uncloseing vertebral canal, somato-sensory evoked potential of both control groups and training gropes could been mensurated when stimulate right or left hind limb. However just after hemi-transecting right spinal cord only stimulate right hind limb could mensurated potential beneath controlateral scalp. The potential was consisted of primary response and secondary discharge. I mensurated amplitude and latency of primary response and duration of secondary discharge.Because these parameters were more sensitive than the others.1.1 After hemi-transected spinal cord the amplitude and duration of both control groups and training groups increased significantly (p<0.05),while 3 days after operation the amplitude and duration all significantly decreased (p<0.05). From 2 or 4 weeks to 10 weeks after operation the amplitude and duration of both control groups and training groups were significantly bigger than the amplitude of normal group (p<0.05) ; synchronously, the amplitude and duration of training groups was significantly respectively bigger than the amplitude of corresponding period of control groups (p<0.05); the amplitude and duration of the group training for 6 weeks was the biggest one among it; that of the control group 8 weeks after operation was the biggest one among it. In a word,the amplitude and duration,contrary to latency, had the same trend of the change.1.2 There are 3 SD rats (25%) among the groups training for 8 and 10 weeks, mensurated somato-sensory evoked potential beneath bilateral scalp when stimulate right hind limb. But this kind of case in normal group,control groups and other training groups were not found. As indicated rehabilitative training could promote functional connection come into being in the central nerve system until at least 8 week later. From 8th week to 10th week after operation the amplitude and duration mensurated from right beneath scalp of the three rats were all significantly respectively smaller than thatthmensurated from corresponding period of left side(p<0.05),while had no significant difference with normal group. Latency mensurated from right side significantly was longer than that mensurated from corresponding left side(p<0.05), while had no significant difference with normal group.2. BDNF positive cells (involved a and y neurons) could be observed in ventral horn in normal spinal cord. BDNF immunoreaction product was mostly located in plasma,only little in nucleus. The distributed area of BDNF immunoreaction product did not change after hemi-transected operation. BDNF positive cells in ventral horn of paralysed side of training group were more than normal group after operation(p<0.05). 6^ week, 8th week and 10th week after the operation BDNF positive cells in ventral horn of paralysed side of training group were significantly respectively more than corresponding period of bilateral of control groups and healthy side of training groups(p<0.05). 2nd week and 4th week after operation BDNF positive cells in ventral horn of healthy side of training group were more than normal group (p<0.05). BDNF positive cells in ventral horn of paralysed side of contral group were more than normal group 2nd week after operation(p<0.05), less than normal group 4th to 8th week after operation(p<0.05). BDNF positive cells in ventral horn of healthy side of contral group were more than normal group 2nd week after operation(p<0.05), less than paralysed side of contral group 4th week after operation(p<0.05).In a word, the expression of BDNF in ventral horn of paralysed side of training group were always commanding to that of normal group after operation,and was most significant 6nd week after operation like parameters of potential3. After acute term BBB grading mark of the healthy (left hind limb) limb of control groups and of training group had no significant difference with that of normal group. 1st day,3ed day, 1st week, 5th week and 8th week after the operation BBB grading mark of the paralysed limb(right hind limb) of control groups were all significantly smaller than that of normal group(p<0.05).BBB grading mark of the paralysed limb of training groups all the time after the operation were all significantly smaller than that of normal group(p<0.05),but from 2nd week after operation BBB grading mark had a steady ascending trend of change.[Conclusion]: 1. The rehabilitative training model what I have set up for rats was practical and reliable.2. There were significant change of somato-sensory evoked potential of rehabilitative training groups,that indicate rehabilitative training can promote to improve conductive access and to produce functional connection. 3. BDNF positive cells in paralysed sides of rehabilitative training groups increased most significant, that indicate the change of expression of BDNF may be the important index of rehabilitation of spinal cord injury.4. BBB grading mark indicate that the function of paralysed limbs of training groups had a steady ascending trend of change.