Expression of Slit and Robo during remodeling of corticospinal tract in cervical spinal cord in middle cerebral artery occlusion rats

Abstract

Background: Slits and Robos were associated with the generation of axons of corticospinal tract during the corticospinal tract (CST) remodeling after the cerebral ischemic stroke (CIS). However, little is known about the mechanism of CST remodeling. In this study, we detected the expression of Slits and Robos in middle cerebral artery occlusion (MCAO) rats to investigate the roles of Slits and Robos in the CIS. Methods: MCAO model was established using modi ed Zea Longa method. Beam walking test (BWT) was conducted to evaluate the motor function. The images of the track of cortical spinal cord beam on day 7, 14 and 21 were observed by anterograde CST tracing. Biopinylated dextan amine (BDA) was used to mark CST anterogradely. Expression of GAP-43 mRNA and GAP-43 protein in cervical spinal cord was detected by Real-Time PCR and Western blot analysis, respectively. The expression of Slit1, Slit2 and Robo1 in cervical spinal cord was detected by immuno uorescence staining.Results: The scores in the model group were signi cantly reduced compared to sham-operation group on day 7 (P<0.001), 14 (P<0.001) and 21 (P<0.001), respectively. There was no signi cant difference in the score on day 7, 14 and 21 of the sham-operation groups (P>0.05). In contrast, signi cant increase was noticed in the scores in model group, presenting a time-dependent manner. More CST staining bers could be observed at the degenerative side in the model group compared with that of the sham-operation group on day 21. GAP-43 mRNA expression in the model group showed signi cant increase compared to that of sham-operation group on day 14 (P=0.015) and 21 days (P=0.002). The expression of GAP-43 protein in model group showed signi cant increase compared to that of sham-operation group on day 14 (P=0.022) and day 21 (P=0.008), respectively. The expression of Slit1 and Slit2 showed increase on day 14 and day 21, while the expression of Robo1 showed signi cant decrease in MCAO rats.