| Objective:To investigate the dynamic expression of hypoxia-inducible factor-la and heat shock protein 70 after MCAO induced acute cerebral infarction at different hours, we measured the concentration of hypoxia inducible factor-la and heat shock protein 70, and analysed the influence of middle cerebral artery occlusion to HIF-la and Hsp70. This study also discussed the relationship between HIF-la and Hsp70, and then provide the experimental basis to cerebral infarction therapeutic targets. Methods:The male and female SD (2-3 months old, weight 250-320g) rats were randomly assigned to three groups:surgery group (MCAO, N=16), sham operation group (N=16) and control group (N=4)。Then, every group divided to 4 groups except control group. Every small group had two chances to be sampled blood by cutting their tails. So every small group sampled blood for 8 times, which contain 0.5 hour,2 hour,3 hour,6 hour,12 hour,24 hour,3 day,7 day eight points. Each group contained 4 rats,2 male and 2 female. MCAO model was induced by modified Longa's method. Then, rats were subject to a neurobehavioral deficit test after awake, only the rats who got 1-3 scores can be chosen, the rats scored 0 points,4 points, or suffered cerebral hemorrhage are out. Blood samples was centrifuged by 1000 rpm centrifuge, then took the upper serum and froze them at-70℃refrigerator, the hemolytic samples must be eliminated. The ELISA method was used to measure the OD values of HIF-1αand Hsp70. Then draw the standard curve by standard concentration. Finally, we calculated HIF-la and Hsp70 expression levels by standard curve and used analysis of variance to evaluate all data at different time and different treatment. Surgery rats were randomly selected to take of TTC staining after the head perfusion by saline to judge if the model is succesful. Results:1) Neurobehavioral deficit scores:surgical group scored:1.63±0.554, sham operation group scored 0 point, the difference was statistically significant.(P <0.05); 2) HIF-la expression:surgical group increased significantly higher than the other two groups, the difference in three treatment groups was statistically significant (P<0.05), and the differences of HIF-la expression levels at eight time points were statistically significant (P<0.05). The trends of HIF-la expression at 8 points:The HIF-la expression in surgical group is higher than sham operation group at 0.5,2,3,6hours four points (P<0.05), while the surgical group compared with the control group at 0.5,2,3,6,12 hours, surgical group's expression is statistically significant higher(P<0.05). The change between different time points:HIF-1αexpression at 12 hours was significantly higher than other groups (P<0.05).3) Hsp70 expression results: The difference between surgical group and sham group at 0.5,2,6,12,24 hours were statistically significant (P<0.05). The surgery group was higher than control group only at 24 hour point (P<0.05). The change in different time points:Hsp70 expression only increased significantly at 24 hour (P<0.05).4) TTC staining:the area right middle cerebral artery supplied was stained white, which imply the infarct areas. Conclusion:1) Modified MCAO model is an ideal animal model for focal cerebral infarction; 2) the cerebral neurobehavioral deficit scores of surgery group is higher than sham operation group; 3) HIF-1αexpression started from 0.5 hour,12 hours reached a peak, HIF-1αinduced a series of cerebral hypoxia response which play an important role on neuro-protection.4) Hsp70 expressed high at 24 hours after cerebral ischemia. As a stress protein, it involved in the neuroprotection of cerebral infarction.5)The HIF-1αand Hsp70 in the unilateral middle cerebral artery occlusion model expressed one after another; 6)The successful TTC staining mean that the model is successful, and the infarct areas is the middle cerebral supplied area.
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