RÉSUMÉ
Objective:To investigate the effect of exercise preconditioning on angiogenesis in ischemic brain tissue in rats with cerebral ischemia-reperfusion injury in the view of VEGF/VEGFR2/dock6 signaling pathway. Method:SD male rats were divided into sham group,model group and exercise preconditioning group by ran-dom number table method,with 18 rats in each group.The sham operation group and the model group were not given any treatment,while the exercise preconditioning group was given adaptive running training for 3 days at a speed of 10 m/min,once a day for 20 minutes each time.After the adaptive training,the exercise preconditioning group was given formal running training for 3 weeks,continuous training for 6 days a week,rest for 1 day,electric treadmill slope of 0°,speed of 15m/min,30min/d.Model group and exercise precondi-tioning group were modified to prepare the middle cerebal artery occlusion(MACO)models by Koizumi thread method,while sham operation group only given skin cutting without thread insertion.Zea longa score and modi-fied neurological severity score(mNSS)were used to score neurological deficit in rats,the relative infarct size of the brain was detected by TTC staining,the morphological changes of the ischemic cerebral cortex was ob-served by HE staining,the expression of CD31 in ischemic cerebral cortex was detected by immunohistochemis-try and the expressions of VEGFA,VEGFR2,Dock6 in ischemic cerebral cortex were detected by western blot. Result:①Zea-Longa scoring:after awaking from anesthetizati,compared with the sham group,the Zea-Longa scores of the other two groups were increased(P＜0.01),and there was no statistical significance in the Zea-Lon-ga scores between the two groups.At 72 hours after reperfusion,compared with the sham group,the Zea-Longa score of the rats in the model group was significantly increased(P＜0.01);compared with the model group,the Zea-Longa score of the rats in the exercise preconditioning group was significantly decreased(P＜0.05).②mNSS scoring:At 72 hours after reperfusion,compared with the sham group,the mNSS score of the rats in the mod-el group was significantly increased(P＜0.01);compared with the model group,the mNSS score of the rats in the exercise preconditioning group was significantly decreased(P＜0.05).③TTC staining:Compared with the sham group,the cerebral infarction volume in the model group was increased(P＜0.01),and compared with the mod-el group,the cerebral infarction volume in the exercise preconditioning group was decreased(P＜0.05).④ HE staining:Compared with the sham group,the model group rats appeared significant pathological changes in the cerebral cortex on the ischemic side.Compared with the model group,the pathological changes of the cerebral cortex on the ischemic side of the rats in the exercise preconditioning group were alleviated.⑤ Immunohisto-chemistry of CD31:Compared with the sham group,the expression of CD31 in the ischemic cerebral cortex of the model group was significantly increased(P＜0.05).The expression of CD31 in the ischemic cerebral cortex of the exercise preconditioning group was further increased(P＜0.05).⑥Western blot of VEGF,VEGFR2 and Dock6:Compared with the sham group,the expressions of VEGF(P＜0.05),VEGFR2(P＜0.05)and Dock6(P＜0.01)in the ischemic cerebral cortex of the model group were significantly increased;compared with the model group,the expressions of VEGF(P＜0.05),VEGFR2(P＜0.05)and Dock6(P＜0.01)in the ischemic cerebral cor-tex of the exercise preconditioning group were further increased. Conclusion:Exercise preconditioning can effectively promote angiogenesis after cerebral ischemia and reduce cerebral ischemia-reperfusion injury,which may be related to the activation of VEGF/VEGFR2/Dock6 signaling pathway.
RÉSUMÉ
Objective:To observe any effect of exercise preconditioning on the levels of hypoxia-inducible factor-1α (HIF-1α) and vascular endothelial growth factor (VEGF) in the brain tissue of rats after induced cerebral ischemia and reperfusion, and how it might promote angiogenesis.Methods:Thirty-six male Sprague-Dawley rats were randomly divided into a sham-operation group, a model group and an exercise preconditioning group, each of 12. After adaptive running training for 3 days, the exercise preconditioning group ran daily for 30 minutes at 15m/min for 14 days, while the other two groups did not exercise. Middle cerebral artery occlusion and reperfusion were then induced in the model and exercise preconditioning groups using the modified Zea-Longa suture method. Rats in the sham-operation group were only cut open to expose the right carotid artery. Right after the modeling, and again 24 hours later neurological deficit was evaluated using the Zea-Longa score and modified neurological severity scoring (mNSS). Infarct sizes were measured using 2, 3, 5-triphenyl tetrazolium chloride staining. Any morphological changes were noted using hematoxylin and eosin (HE) staining, and the expression of CD31 protein, hypoxia-inducible factor-1α and vascular endothelial growth factor in the ischemic cerebral cortex were quantified immunohistochemically.Results:Right after the modelling, compared with the sham-operation group, the average Zea-Longa scores of the model and exercise groups had increased significantly, but were not significantly different from each other. Twenty-four hours later the average Zea-Longa score, mNSS score and relative cerebral infarction area of the model group had increased significantly compared with the sham-operation group, while the exercise preconditioning group′s averages had decreased significantly. The HE staining showed that compared with the sham-operation group, pathological changes such as loose tissue, reduced number of nerve cells, nucleolysis, and vacuolization of the cerebral cortex on the ischemic side were found in the model group. Compared with the model group, the pathological changes in the exercise preconditioning group were less serious. The levels of CD31 protein, HIF-1α and VEGF in the ischemic cerebral cortexes of the model group had by then increased significantly. But compared with the model group, those levels had increased more in the exercise preconditioning group.Conclusion:Exercise preconditioning can effectively promote angiogenesis after cerebral ischemia and reduce chronic injury. That may be related to the activation of the HIF-1α and/or VEGF signaling pathways.
RÉSUMÉ
Motor timing is an important part of sensorimotor control. Previous studies have shown that beta oscillations embody the process of temporal perception in explicit timing tasks. In contrast, studies focusing on beta oscillations in implicit timing tasks are lacking. In this study, we set up an implicit motor timing task and found a modulation pattern of beta oscillations with temporal perception during movement preparation. We trained two macaques in a repetitive visually-guided reach-to-grasp task with different holding intervals. Spikes and local field potentials were recorded from microelectrode arrays in the primary motor cortex, primary somatosensory cortex, and posterior parietal cortex. We analyzed the association between beta oscillations and temporal interval in fixed-duration experiments (500 ms as the Short Group and 1500 ms as the Long Group) and random-duration experiments (500 ms to 1500 ms). The results showed that the peak beta frequencies in both experiments ranged from 15 Hz to 25 Hz. The beta power was higher during the hold period than the movement (reach and grasp) period. Further, in the fixed-duration experiments, the mean power as well as the maximum rate of change of beta power in the first 300 ms were higher in the Short Group than in the Long Group when aligned with the Center Hit event. In contrast, in the random-duration experiments, the corresponding values showed no statistical differences among groups. The peak latency of beta power was shorter in the Short Group than in the Long Group in the fixed-duration experiments, while no consistent modulation pattern was found in the random-duration experiments. These results indicate that beta oscillations can modulate with temporal interval in their power mode. The synchronization period of beta power could reflect the cognitive set maintaining working memory of the temporal structure and attention.