| Objectives:To investigate the correlation between fingolimod (FTY720) and RhoA expression and the function of hind limbs after actue spinal cord injury (SCI) in rats by detecting RhoA expression and the recovery of hind limbs'function in different phase after post-surgery. Further, to explore the possible mechanism of FTY720 in the treatment of SCI in order to supply new thread or way for the repair of SCI.Methods:(1)A rat model of acute SCI was established with a modified Allen's method. And the injuried segment was T10 while the impacting energy was 40 gcf. Nity Sprague-Dawley (SD) rats were divided randomly into three groups: sham-operation group or A group (n=18), injury group or B group (n=36), and the group treated with FTY720 or C group (n=36). The sham-operation group and injury group received IP injection of normal saline at 30 minutes after SCI, and the FTY720 group received FTY720 0.5 mg·kg-1 in the same way. Three rats in group A and six rats in group B and C were taken out respectively after 1 day, 3 day, 7 day, 14 day and 21 day after successfully modeling. The spinal cord injury area in these rats were cut out and bisected into two segments which were respectively used to be detected the expression of RhoA mRNA and protein by reverse transcription-polymerase chain reaction (RT-PCR) and western blotting technique. Observe RhoA expression in different phase after SCI on the double level of gene expression and protein translation. (2) The injuried spinal cord tissue in the remaining rats were cut out to detect the changes of the spinal cord tissue by hematoxylin and eosin (HE) stain in order to observe the functional recovery of spinal cord. (3)BBB score was evaluated in each group at every phase after modeling to check motor functional recovery after SCI.Results:(1) RT-PCR and western blotting showed: The expression of RhoA mRNA and protein in the injury group rose at 1 day and became markedly at 3day, reached the peak at 7 day, and still maintained high level at 14 day and 21 day but a little lower than the former after injury. Between injury group and the other two groups of FTY720 and sham-operation, the result had statistically difference at the same point (P<0.05). Meanwhile, the expression of RhoA in FTY720 group at 1 day, 3 day and 7 day were higher than those in sham-operation group (P<0.05), contrarily, the expression between the two groups was not obviously difference at 14 day and 21 day (P>0.05). And the expression in sham-operation group kept a constant level throughtout the experiment. (2)HE stain displayed: The pathological change of the spinal cord tissue in sham-operation group was similar to the normal, while that in FTY720 group visibly ameliorated better than in injury group. (3)BBB score indicated: The BBB scales reached 20 or 21 in sham-operation after post- surgery. And all rats in FTY720 group and injury group were instantly observed typical paraplegia syndrome and the BBB score was 0. The score of sham-operation group was significantly higher that of injury and FTY720 group (P<0.05). And the day at 7, 14, 21 and 35 after postinjury, the score of FTY720 group was higher than in injury group (P<0.05).Conclusion:After acute SCI, the expression of RhoA mRNA and protein obviously increase, and has evident time curve. By prohibiting the expression of RhoA, FTY720 may ameliorate the microenvironment of injury area in order to attenuate secondary SCI and improve the recovery of neurological function and hind limb function after acute SCI in rats. |
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