The Effect Of Picroside Ⅱ On The Expression Of Matrix Metalloproteinase-9after Cerebral Ischemic Injury In Rats

Objective:To explore the effect of picroside Ⅱ on the expression of matrix metalloproteinase-9(MMP-9) and optimize the therapeutic dose and time window after cerebral ischemic injury in rats.Methods:A total of174Wistar rats were randomly divided into cerebral ischemia group(model group)(n=5×3), control group(n=5×3) and treatment group with picroside Ⅱ(n=16×3×3).The forebrain ischemia models were established by bilateral common carotid artery occlusion (BCCAO) methods. And the rats in treatment group were randomly grouped according to orthogonal experimental design of [L16(45)] and injected intraperitoneally with picroside Ⅱ according to the corresponding doses designed in the orthogonal layout. The morphology of nerve cell and ultrastructure of brain tissue were observed by haematoxylin eosin (HE) staining and transmission electron microscopy (TEM) respectively. The expression of MMP-9protein was determined by immunohistochemical (IHC) staining and Western blotting (WB). The expression of MMP-9mRNA was detected by reverse transcription polymerase chain reaction (RT-PCR).Results:The expressions of MMP-9in brain tissue in model group rats were increased significantly and the brain tissue were damaged seriously than those in control group. After treated by picroside Ⅱ, the expressions of MMP-9in brain tissue in treatment group rats were reduced obviously and the structure of brain tissue was also improved obviously than those in model group. The optimal therapeutic dose and time window of picroside Ⅱ in treating cerebral ischemic injury were ischemia2.0h with10mg/kg body weight according to the HE staining, ischemia2.0h with10mg/kg according to the IHC staining, ischemia1.5h with10mg/kg according to WB and ischemia1.5h with20mg/kg according to RT-PCR respectively.Conclusion:It is conclude that picroside Ⅱ could protect brain tissue against ischemia injury by reducing the expressions of MMP-9after cerebral ischemic injury in rats. According to the principle of the minimization of medication dose and maximization of therapeutic time window, it is considered that the best therapeutic dose and time window of picroside Ⅱ in cerebral ischemic injury is injected intraperitoneally with10-20mg/kg at ischemic1.5-2.Oh.