| Objective:This study investigated the expression of inflammatory cytokines, neuronalapoptosis and alteration of blood-brain barrier with respect to structure and functionin middle cerebral artery occlusion (MCAO) rats, to provide evidence ofpathologically grading cerebral infarction and corresponding brain protectivetreatment.Methods:1. A total of120SD rats were randomly assigned to normal group and theMCAO model groups (0h,0.5h,1h,2h,4h,6h,12h,24h,48h,4d,6d,10d,14d and18d), with8rats in each group. MCAO model was established using the intraluminalsuture method and nerve function was evaluated with mNSS.2. The serum levels of tumor nectosis factor-α (TNF-α), interleukins-1β (IL-1β)and interleukins-6（IL-6） were measured using ELISA.3. The levels of inflammatory cytokines（TNF-α, IL-1β and IL-6）, and matrixmetalloproteinase-9(MMP-9) in brain tissue were detected usingimmunohistochemical staining（IHC）.4. The neuronal apoptosis in MCAO rats were examined by TUNEL assay.5. Functional changes of blood-brain barrier were evaluated with Evans blue-ultraviolet spectrophotometry.Results:1.Comparing to the normal control, the serum levels of TNF-α, IL-1β and IL-6significantly increased at0.5h,1h and4h (P <0.05), and reached to the first peak at4h,6h and12h (P <0.05), respectively; the second peak levels of TNF-α and IL-1βwere observed both at the10th d (P <0.05), versus IL-6at the4th d (P <0.05) afterMCAO in rats.2.In brain tissue, the number of TNF-α+cells significantly enhanced at2h (P <0.05), reached to the first peak at24h (P <0.05) and then returned to normal at the 4th day; but it again slowly increased at the6th day and gradually dropped at14thday (from the4th day to18th day, P>0.05). With respect to the number of IL-1β+and IL-6+cells, they both initiated significant enhancement at0.5h (P <0.05),respectively reached to the first peak at12h and24h (P <0.05), and the second peakat the6th day (P <0.05) after MCAO in rats in comparison with the normal control.3.In contrast with the normal control, the number of apoptosis cells remarkablystarted rising at2h, to the peak at24h (P <0.001) and remained high at48h (P <0.001).It slowly went down thereafter and went back to the normal at the18thd((P=0.196).4.In terms of MMP-9, both in the ischemia side and the contralateral braintissue, its expression were significantly climbed at0h (P <0.05), and peaked at48h(P <0.001), then decreased after the4thd (P <0.05). At all the time points in modelgroups, MMP-9expression in the lesion side were significantly higher than thecontralateral side（P＜0.01）.5.The leackage of EB in the lesion side and contralateral brain tissue, ascompared with the normal group, apparently elevated at2h and4h (P <0.001),respectively； and both peaked at24h (P <0.001), then gradually reduced. And theleackage of EB in brain tissue significantly differed between ischemia side andcontralateral side at every time piont（P＜0.05）.Conclusion:The nervous tissue suffered from ischemic and necrotic damage, apoptosis andblood-brain barrier destruction during the early12h-48h after ischemia reperfusion.Then the inflammation and tissue repair played the primary role from6d to10d.Finally,14days later, inflammation faded away, gliocytes scar formed andblood-brain barrier reconstructed. |
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