| Objective:Stroke is still the main cause of long-term disability,and there is no effective treatment.Panax notoginsenoside Rbl is an important active ingredient found in pseudo-ginseng which effective for cerebrovascular diseases.The cerebral cortex is an important structure that dominates somatic sensation and movement,which is also sensitive to many chemical damages,especially ischemia.To explore the protective mechanism of panax notoginsenoside Rbl on cerebral ischemia by studying the effect of panax notoginsenoside Rbl on the expression of brain derived neurotrophic factor and its precursor neurotrophic factor in focal cerebral ischemic rats.Methods:48 SD male rats were randomly divided into sham group,ischemic model group,panax notoginsenoside Rbl therapy group(100 mg/kg)and the positive medicine control group(nimodipine,1 mg/kg),with 12 rats in each gcroup and each was divided into three subgroups which were 3 days,7 days,and 14 days.The ischemic model were made by photothrombosis,the drug was administered 2 times a day after the operation,the rats in the sham and model group were intraperitoneally injected with the same amount of normal saline at 4 hours after operation.Neurologic deficit was detected by corner test,tape-femoval test and modified neurological severity score(m NSS)at the corresponding time point,before and after operation(same day,3 days,7 days,and 14 days.).Rats were sacrificed after treated with medicine in 3 days,7 days,and 14 days..Western blotting and immunohistochemistry method were used to detect the expression of TrkB,sortilin,tPA,PAI-1 and p75NTR.Elisa were used to detect the concentration of mBDNF and proBDNF.Results:Behavioral tests results:rats suffered from different degrees of sensorimotor dysfunction after cerebral ischemia.Assessment of rats deficit through corner test,adhesive tape removal test and mNSS.Compared with the model group,the sensorimotor disorders in the panax notoginsenoside Rbl group and nimodipine group were significantly improved(P<0.05).,?Corner test:the model group preferred to turn right(P<0.01);compared with the model group,the number of rightward turns in group panax notoginsenoside Rbl and nimodipine decreased(P<0.05),and showed a time-dependent manner.?Adhesive tape removal test:compared with the sham group,the time of contact adhesive tape and the time of tape removal were prolonged in the model group(P<0.05);compared with the model group,the time of contact tape and tearing tape in the panax notoginsenoside Rb1 group and nimodipine group shortened(P<0.05),especially at 7 days and 14 days(P<0.05).?mNSS:there were no neurological deficits in the sham group(score 0);the mNSS score of the model group was higher than that of the sham group(P<0.01);compared with the model group,the neurological deficit score of the panax notoginsenoside Rbl and nimodipine group decreased(P<0.05);compared with the 3 days,the scores in the 7 days and the 14 days groups were lower,but there was no significant difference(P>0.05).Western blotting results:?compared with sham group,the expression of TrkB,sortilin,P75NTR,tPA and PAI-1 proteins in model group increased significantly(P<0.05);?compared with the model group,panax notoginsenoside Rbl and nimodipine significantly decreased the expression of sortilin,P75NTR and PAI-1 proteins(P<0.05),especially at 14 days(P<0.05);?compared with the model group,panax notoginsenoside Rb1 and nimodipine increased the expression of TrkB and tPA significantly(P<0.05),and showed a time-dependent manner,especially in the 14 days(P<0.05).?there was no significant difference between panax notoginsenoside Rb1 and nimodipine group(P>0.05).Immunohistochemistry result:(Dthe expression of P75 was seldom in the sham group;and a large number of P75 positive expressions in the cytoplasm and membrane(P<0.05)which were found at 3 days,7 days,and 14 days after cerebral ischemia.All expression was slightly decreased with time,the optical density increased(P<0.05),which slightly decreased with time;the positive expression of P75 was reduced by panax notoginsenoside Rb1 and nimodipine on 3 days,7 days,and 14 days(P<0.05).There was no significant difference between panax notoginsenoside Rbl and nimodipine group(P>0.05).?A small amount of sortilin positive expression was found in the sham operation group.Compared with the sham group,there was a large number of cytoplasm stained positive cells(P<0.05)in the ischemic model group,and the optical density increased significantly(P<0.05).The positive expression of sortilin in panax notoginsenoside Rbl and nimodipine treatment group decreased significantly on 3 days,7 days,and 14 days(P<0.05),and showed time dependence.The expression of sortilin decreased significantly at 14 days,and the optical density decreased significantly with time(P<0.05).There was no significant difference between panax notoginsenoside Rbl and nimodipine group(P>0.05).?In the sham group,a small amount of TrkB positive expression was found in the cytoplasm and membrane,and the number of positive cells in the model group increased(P<0.05),optical density increased(P<0.05).The expression of TrkB in the panax notoginsenoside Rb1 and nimodipine groups on 3 days,7 days,and 14 days was significantly increased(P<0.05),and was time-dependently and optical density increased(P<0.05).There was no significant difference between panax notoginsenoside Rb1 and nimodipine in different time points(P>0.05).Elisa results shows:the level of mBDNF/proBDNF in the model group is higher than that of the sham group(P<0.05).Compared with the model group,the level of mBDNF in panax notoginsenoside Rb1 and nimodipine groups were increased further(P<0.05),while the level of proBDNF decreased(P<0.05)and all showed time-dependently.Compared with the 3 days group,the level of BDNF/proBDNF in panax notoginsenoside Rbl and nimodipine 14 days groups increased significantly(P<0.05).Conclusion:panax notoginsenoside Rbl can significantly improve the deficits induced by ischemic stroke,and time-dependently increased the expression of BDNF,TrkB and its processing enzyme(tissue plasminogen activator,TPA),while reducing the expression of proBDNF,p75NTR,sortilin,and type I plasminogen activator inhibitory factor(PAI-1),which ultimately mediates the protective effect of neurons.Therefore,panax notoginsenoside Rbl can effectively improve the cerebral ischemia injury by activating BDNF/TrkB signaling pathway and inhibiting proBDNF/sortilin/p75NTR signaling pathway. |
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