Changes Of Synand BDNF Expression In The Different Parts Of Rats Central Nervous System Following Spinal Cord Injury

[Objective]: Changes of expression of synaptophysin(SYN) and brainderived neurotrophic factor (BDNF) in the different parts of rats'central nervous system following spinal cord contusion have been studied in order to provide the experimental evidences for the mechanisms of regeneration and repair after spinal cord injury.[Materials and Methods]: 1.experimental animal and groups:42 healthy adult srague-daweley rats (male and female informality),whose mean weight 220±20g, were divided into 7 groups at random: control group; spinal cord injury groups (1d group, 3d group, 7d group, 14d group, 21d group, 28d group). 2.establish contused spinal cord injury SD rat model: The spinal cord injury at T12 segment of rats was made with modified Allen apparatus. BBB graded everyday before and after operation. 3.materials and estimates: The rats were killed in different days. The fixed spinal cord segments (the T12 spinal cord segments) hemisphere and brainstem were taken out from the rats. These tissues were made into frozen sections in 25μm thickness, taken one section every five. The immunohistochemical ABC method was applied to detect the distribution and expression of SYN and BDNF in spinal cord, brainstem and hippocampus in different days after SCI.Counting BDNF positive neurons with Olympus microscope and take pictures by cinema. Computer image analysis was used to measure the average optical density of SYN and BDNF. To measure the positive units of SYN. All datas were analyzed by anova.[Result]: 1. The pathological observing: There were significantly haemorrhage, edema,degeneration,vacuole in SCI groups.2. The expression of SYN : Distribution points in the nervous system of all nerve endings. After ABC staining SYN express for brown granules. (1) In the normal rat spinal cord,expression limited to gray. SYN begin decreasing express following spinal cord contused, and come to climax point after administration 14 days, then increased. The number of the experimental groups was significantly higher than the control group exapt for 1 day. Changes of psitive units similar to the optical density. (2) In the medulla oblongata mainly distributed in the nucleus, such as olives nucleus. There was no significant difference among all of the groups. Changes of psitive units similar to the optical density. (3) Under light microscopy, the synaptop hysinir products were localized mainly in the form of particles and dots and were not even in all regions of hippocampal formation. In the CA3 of hippocampus, SYN begin decreasing express following spinal cord contused lday, and come to climax point after admimstration 3 days, and keep high expression level after administration 7 days. There was no significant difference between 1 day and the control group.3. The expression of BDNF positive cell: (1) There are a few BDNF positive cells distribution in ventral horn and dorsal horn gray matter of normal spinal cord. The BDNF positive substances located in plasma and dendrites and axons and didn't staining on nucleus. BDNF begin increasing express following spinal cord contused lday, and come to climax point after administration 14 days, and keep high expression level after administration 28 days. All operational groups are increasing contrast to normal control group. (2) The number of positive cells was gradually increased in the medulla oblongata following spinal cord contused. The number of the experimental groups was significantly higher than the control group except for lday. (3) In pontine the number of BDNF come to climax point after administration 7 days, then dropped. There was no significant difference among 1 day, 3 day and the control group. Changes of MOD similar to the positive cells.4. The handlimb locomotor function had being steady in control group. All animals' BBB scores were 0 in 1 day and increased gradually after 14 days. The BBB scores still to remain lower than control group.[Conclusion]: 1. The improved spinal cord injury model was practical and reliable and was accorded with clinic.2. SYN has been called different changes with the change of time following spinal cord contusion. There was no significant difference in medulla oblongata. There were significant difference in spinal cord and hippocampus 3 days after injury.3. BDNF has been called different changes with the change of time following spinal cord contusion. Following spinal cord contusion, BDNF expression was significantly increased, suggesting that BDNF may repair spinal cord injury in the early reactions play a role. There were significant difference in medulla oblongata 3 days after injury. The same thing happened in hippocampus after 7 days.4. There are changes of BDNF and SYN in the different parts of rats' central nervoussystem following spinal cord injury. SYN can be used as renewable evaluation of the more quantifiable indicators.