The Effect Of Apelin Protein In The Rats' Spinal Cord Cell Units After The Sciatic Nerve Sutured

Objective:To investigate the effect of Apelin protein on apoptosis of spinal cord anterior horn neuron after rat sciatic nerve injury, which can gives basis to further research of apelin protein in preventing secondary spinal cord injury.Methods:Sciatic nerve trasection and repair were done in 48 rats as experimental models.The rats were divided into two groups with 24 each. Rats of groups A received Apelin protein injection in the suture stump after the operations,while rats of group B received NS as controls.L4-6 spinal cord were harvested at 4h,8h,24h,72h and 7,14 days postoperatively.the samples were fixed,dehydrated and sliced into 5μm thick frozen section. Apoptosis was detected with TUNELResults:Only few apoptosis was seen in spinal cord neurons of group A at 4h after operation, and at 8h, the typical apoptotic neurons could be observed of group A (showed nuclear condensation, chromatin condensation, or the formation of irregular fragments, fluorescent yellow). The number of apoptotic cells reached a peak at 24h after operation, In particular, a large number of glial cells was apoptosis. The apoptosis of neurons and glial cells are gradually reduced during 72h to 7d after operation, there is not typical of different stages of apoptosis, showing that a small amount of capillary proliferation. At 2 weeks there still exists a few apoptotic cells. At each time point apoptosis of spinal cord glial cells are visible, and neuronal apoptosis increased significantly. But the number of apoptosis in experiment group were significantly less than the control group in anterior horn neurons of spinal cord.The glial cells and anterior horn neurons have reached different degrees of apoptosis in group B at 4h after operation (Nucleus stained with brown granules, and no typical apoptotic bodies), At 8h to 24h, The positive labeled cells gradually increased in group B, showing that a large number of spinal anterior horn neurons and glial cells got apoptosis. Apoptotic cells reached a peak after 72h, and then gradually reduced, and the number of apoptotic cells at 7d is a little more than that at 8h after operation, but the extent of apoptosis reduces, with no typical apoptosis. TUNEL-positive cells can still be seen in spinal anterior horn neurons at 14d after operation. The difference of the cell death numbers was of significance (P<0.05).Conclusion:Apelin protein in the suturing stump maybe protect spinal cord neurons after rat sciatic nerve injury.