Effect of picroside II on expression of myelin basic protein after cerebral ischemia injury in rats

AIM:To verify the neuroprotective effect and optimize the therapeutic dose and time window of picroside Ⅱ on cerebral ischemic injury in rats.METHODS:The forebrain ischemia model was established by the method of bilateral common carotid artery occlusion(BCCAO).The successful model rats were randomly divided into 16 groups according to orthogonal design and treated by intraperitoneal injection of picroside Ⅱ at different ischemic time poinis and different doses.The changes of the nerve fiber myelin were observed by fast green staining.The immunohistochemical assay and Western blotting were used to quantitatively and qualitatively determine the expression of myelin basic protein(MBP).The mRNA level of MBP in the brain tissues was tested by reverse transcription polymerase chain reaction(RT-PCR).RESULTS:Picroside Ⅱ increased the expression of MBP and decreased demyelination after cerebral ischemic injury.The best therapeutic time window and dose were:(1) ischemia for 2.0 h with picroside Ⅱ at dose of 10 mg / kg according to the results of fast green staining;(2) ischemia for 2.0 h with the dose of 10 mg / kg according to the results of immunohistochemical assay;(3) ischemia for 2.0 h with the dose of 10 mg / kg according to the analysis of Western blotting;(4) ischemia for 1.5 h with the dose of 20 mg / kg according to the detection of RT-PCR.CONCLUSION:Given the principle of the lowest therapeutic dose with the longest time window,the optimized therapeutic dose and time window for rat cerebral ischemic injury is intraperitoneal injection of picroside Ⅱ at the doses of 10 ~ 20 mg / kg and the time window of ischemia for 1.5 ~ 2.0 h.