| Objective:To evaluate the neuroprotective effects and its mechanism of kaempferol on focal cerebral ischemia reperfusion(I/R) in rats. To observe the effect of kaempferol on hippocampal neurons ultrastructure and TLR4(Toll-like receptor4,TLR4)/MyD88(myeloid differentiation factor 88,MyD88)/NF-k B(nuclear factor-k B, NF-k B) pathway after focal cerebral ischemia reperfusion(I/R) in rats.Methods:1. Grouping of experimental animals:One hundred and twenty male SD rats, weighing 260-300g, were randomly divided into six groups: sham operation group, MCAO group, low (5 mg·kg-1),middle (10 mg·kg-1) and high (20 mg·kg-1) doses of kaempferol groups and nimodipine group.2. Focal cerebral ischemia in rats was established by inserting a monofilament suture into internal carotid artery for 1.5h and then reperfused for 24h(MCAO). The effects of kaempferol on neurological deficit scores, the infarction volume of brain and the pathological changes after HE stain were observed. And the changes of hippocampal neurons ultrastructure in every group’s rats were observed by transmission electron microscopy.3. The expression of TLR4, MyD88and NF-k Bp65 in cortex and hippocampal neurons of rats was determined by immunohistochemistry. And the contents of TNF-a and IL-1 β in serum were measured by ELISA kits.Results:1. The neurological scores:the sham operation group had no neurological symptoms defect. The neurological scores of MCAO group were higher than that of sham operation group (p<0.01),which proved this model was successful. Compared with the MCAO group, kaempferol 10 mg·kg-1,20 mg·kg-1 administration groups and the nimodipine group can significantly reduce neurological scores (p<0.01).And there was no significant difference between kaempferol 5 mg·kg-1 administration group and the MCAO group (p>0.05).2. Infarction volume:the sham operation group had no white infarction volume. But compared with the sham operation group, the MCAO group showed significant infarction volume (p<0.01), which proved this model was successful. Compared with the MCAO group, infarction volume of kaempferol 10 mg·kg-1,20 mg·kg-1 administration groups and the nimodipine group reduced observably (p<0.01). And there was no significant difference between kaempferol 5 mg·kg-1 administration group and the MCAO group (p>0.05).3. HE staining:in the sham operation group, hippocampal neurons’ form and structure was normal. The neurons were in good arrangement. In the MCAO group, hippocampal neurons distributed uneveuly and cell nucleus contracted, which proved this model was successful. Compared with the MCAO group, kaempferol administration groups and the nimodipine group improved observably.4. Neurons was observed by transmission electron microscopy:in the sham operation group, both of the cell membrane and nucleus were normal, and organelles were abundant. In the MCAO group, cytoplasm was empty, and the cell nucleus showed edema. Cells in kaempferol administration groups and the nimodipine group improved observably, especially cells in kaempferol 20 mg·kg-1 administration group and the nimodipine group. This proved that kaempferol had neuroprotective effects.5. Immunohistochemistry:compared with the sham operation group, the expression of TLR4, MyD88 and NF-κ Bp65 in cortex and hippocampal CA1 region of the MCAO group increased significantly. Compared with the MCAO group, each treated group decreased significantly, especially in kaempferol 20 mg·kg-1 administration group and the nimodipine group. 6. ELISA:compared with the sham operation group, the contents of TNF-a and IL-1 β in serum increased significantly. Compared with the MCAO group, each treated group decreased significantly, especially in kaempferol 20 mg·kg-1 administration group and the nimodipine group.ConclusionTreatment with kaempferol is beneficial to protect brain against focal cerebral ischemia reperfusion in rats. And its mechanism might be attributed to inhibiting the expression of TLR4/MyD88/NF-k B pathway. |
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