Effects of total saponins of Panax notoginseng on immature neuroblasts in the adult olfactory bulb following global cerebral ischemia/reperfusion

The main active components extracted from Panax notoginseng are total saponins. They have been shown to inhibit platelet aggregation, increase cerebral blood flow, improve neurological behavior, decrease infarct volume and promote proliferation and differentiation of neural stem cells in the hippocampus and lateral ventricles. However, there is a lack of studies on whether total saponins of Panax notoginsertg have potential benefits on immature neuroblasts in the olfactory bulb following ischemia and reperfusion. This study established a rat model of global cerebral ischemia and reperfusion using four-vessel occlusion. Rats were administered total sa- ponins of Panax notoginseng at 75 mg/kg intraperitoneally 30 minutes after ischemia then once a day, for either 7 or 14 days. Total saponins of Panax notoginseng enhanced the number of dou- blecortin （DCX）＋ neural progenitor ceils and increased co-localization of DCX with neuronal nuclei and phosphorylated cAMP response element-binding/DCX＋ neural progenitor cells in the olfactory bulb at 7 and 14 days post ischemia. These findings indicate that following global brain ischemia/reperfusion, total saponins of Panax notoginseng promote differentiation of DCX＋ cells expressing immature neuroblasts in the olfactory bulb and the underlying mechanism is related to the activation of the signaling pathway of cyclic adenosine monophosphate response element binding protein.

Total Saponins of Panax notoginseng Activate Akt/mTOR Pathway and Exhibit Neuroprotection in vitro and in vivo against Ischemic Damage

Objective:To reveal the neuroprotective effect and the underlying mechanisms of a mixture of the main components of Panax notoginseng saponins(TSPN)on cerebral ischemia-reperfusion injury and oxygenglucose deprivation/reoxygenation(OGD/R)of cultured cortical neurons.Methods:The neuroprotective effect of TSPN was evaluated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide(MTT)assay,flow cytometry and live/dead cell assays.The morphology of dendrites was detected by immunofluorescence.Middle cerebral artery occlusion(MCAO)was developed in rats as a model of cerebral ischemia-reperfusion.The neuroprotective effect of TSPN was evaluated by neurological scoring,tail suspension test,2,3,5-triphenyltetrazolium chloride(TTC)and Nissl stainings.Western blot analysis,immunohistochemistry and immunofluorescence were used to measure the changes in the Akt/mammalian target of rapamycin(mTOR)signaling pathway.Results:MTT showed that TSPN(50,25 and 12.5μg/m L)protected cortical neurons after OGD/R treatment(P<0.01 or P<0.05).Flow cytometry and live/dead cell assays indicated that 25μg/m L TSPN decreased neuronal apoptosis(P<0.05),and immunofluorescence showed that 25μg/m L TSPN restored the dendritic morphology of damaged neurons(P<0.05).Moreover,12.5μg/m L TSPN downregulated the expression of Beclin-1,Cleaved-caspase 3 and LC3 B-Ⅱ/LC3 B-Ⅰ,and upregulated the levels of phosphorylated(p)-Akt and p-mTOR(P<0.01 or P<0.05).In the MCAO model,50μg/m L TSPN improved defective neurological behavior and reduced infarct volume(P<0.05).Moreover,the expression of Beclin-1 and LC3 B in cerebral ischemic penumbra was downregulated after 50μg/m L TSPN treatment,whereas the p-mTOR level was upregulated(P<0.05 or P<0.01).Conclusions:TSPN promoted neuronal survival and protected dendrite integrity after OGD/R and had a potential therapeutic effect by alleviating neurological deficits and reversing neuronal loss.TSPN promoted p-mTOR and inhibited Beclin-1 to alleviate ischemic damage,which may be the mechanism that underlies the neuroprotective activity of TSPN.

Attenuation of Brain Inflammatory Response after Focal Cerebral Ischemia/Reperfusion with Xuesaitong Injection (血塞通注射液) in Rats

Objective： To investigate the neuro-protective effect of Xuesaitong Injection （血塞通注射液, XST） on brain inflammatory response after transient focal cerebral ischemia/reperfusion in rats. Methods： Focal cerebral ischemia/reperfusion models of male rats were induced by transient occlusion for 2 h of middle cerebral artery （MCA） which was followed by 24 h reperfusion. XST was administered through intraperitoneal injection of 25 mg/kg or 50 mg/kg at 4 h after the onset of ischemia. After reperfusion for 24 h, the neurological function score was evaluated, the brain edema was detected with dry-wet weight method, the myeloperoxidase （MPO） activity and the expression of intercellular adhesion molecule-1 （IOAM-l） of ischemic cerebral cortex and caudate putamen was determined by spectrophotometry and immunohistochemistry respectively. Results： XST not only lowered neurological function score at the dose of 50 mg/kg, but reduced brain edema and inhibited MPO activity and IOAM-1 expression as compared with the ischemia/reperfusion model group （P〈0.01）. Conclusion： XST has a definite effect on inhibiting the expression of IOAM-1 and neutrophil infiltration in rats with cerebral ischemia/reperfusion when treatment started at 4 h after ischemia onset, and also attenuates inflammation in the infarcted cerebral area.