| Objective: To explore the changes on the expression of IGF- I , PDGF, SP and VIP after hemisected spinal cord injury (hSCI). Futhermore, the relationship of IGF- I , PDGF, SP, VIP and spinal cord plasticity were studied.Methods: 24 adult Srague-Daweley rats were randomly divided into sham operational-group and hSCI groups at day 3,7,21, 6 rats in each group. The spinal cord was hemisected between T13 and L1, animals surviving for 3, 7 and 21 days after operation respectively. The L3 spinal cord of every group was made into frozen sections (20 μ m) in series, then stained under the same condition with specific IGF- I , PDGF, SP and VIP antibody by the immunohistochemistry ABC method. The number of IGF- I , PDGF, VIP-IR positive neurons in the ventral horn of spinal cord and the number of SP positive varicosities in lamina Ⅱ of spinal cord were analyzed by One-Way ANOVA and q test.Results: In the normal rats, IGF- I , PDGF immunoreactants can be observed in plasma of neurons in the ventral horn. SP immunoreactants mainly existed in varicosities of lamina Ⅱ. VIP immunoreactants appeared in plasma of neurons in the ventral horn.After hSCI, the number of IGF- I positive neurons in bilateral ventral horn apparently increased from 3rd day to 21st day compared with that of sham operational-group. The number of PDGF positive neurons in intact side in 3d groups were more than that of the sham operational-group, then decreased a little bit 7 days after operation and recovered to normal in 21d group in intact side. In the injured side ,there was no change.Compared with sham operational-group, the number of SP positive varicosities in bilateral apparently increased 3 days after hSCI, but decreased a little bit 7 days after operation, then recovered to normal in 21 d group. Interestedly, the number of SP positive varicosities in intact side was higher than those in injured side. After hSCI, the number of VIP positive neurons in bilateral ventral horn apparently increased in the 3d group, kept to 2Id group in intact side, but recovered to normal in 7 day in the injured side.Conclusion: 1. The number of IGF-1 and PDGF positive neurons increased in the ventral horns of spinal cord following hSCI, which indicated that the increased endogenous IGF- I and PDGF may play an important role in repairment of nerve injury after hSCI. 2. SP, as a neurotransmitter of nociceptive information, was related to the process of hSCI. 3. The number of VIP positive neurons increased in ventral horns following hSCI, which showed that VIP may be related to the spinal cord injury and repairment after hSCI.
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