Effects of Panax notoginseng Saponin on Neurons Based on Oxygen-Glucose Deprivation/Reoxygenation after Focal Cerebral Ischemia

Abstract

We aimed to evaluate the effects of Panax notoginseng saponin on neuronal apoptosis and neuroprotection based on oxygen-glucose deprivation/reoxygenation in rats with focal cerebral ischemia. 100 rats were randomly divided into sham operation, middle cerebral artery occlusion model, low-dose Panax notoginseng saponin (10 mg/kg), medium-dose Panax notoginseng saponin (25 mg/kg) and high-dose Panax notoginseng saponin (50 mg/kg) groups. The model of focal cerebral ischemia was established by middle cerebral artery occlusion. For sham group, the right common, external and internal carotid arteries were only dissociated, without ligation or insertion. After modeling, Panax notoginseng saponin groups were intraperitoneally injected with Panax notoginseng saponin. Hippocampal neurons isolated from normal rats were randomly divided into control, oxygen-glucose deprivation/reoxygenation model, 1 μmol/l, 5 μmol/l and 20 μmol/l oxygen-glucose deprivation/reoxygenation+Panax notoginseng saponin groups. Neurological function was scored by Longa method and neuron morphology was observed. Neuronuclear antigen and neuroepithelial stem protein in brain tissues were detected by immunohistochemistry. The survival rate of neurons, lactate dehydrogenase leakage, neuronal apoptosis and expression levels of protein kinase B, phosphorylatedprotein kinase B and apoptosis-related proteins B-cell lymphoma 2, Bcl-2-associated X protein and caspase-3 were examined by cell counting kit-8 assay, lactate dehydrogenase kit, Hoechst 33 342 staining and Western blotting, respectively. Compared with model group, Panax notoginseng saponin groups had significantly lower neurological function scores (p<0.05). Panax notoginseng saponin significantly relieved neuronal injury and increased neuronuclear and neuroepithelial stem protein-positive cells (p<0.05). It significantly raised the survival rate of neurons, reduced lactate dehydrogenase leakage and inhibited neuronal apoptosis dose-dependently. Panax notoginseng saponin up-regulated the protein expressions of phosphorylated-protein kinase B/protein kinase B and B-cell lymphoma 2 and down-regulated those of Bcl-2-associated X protein and caspase-3 dose-dependently. It can protect against and repair neuronal injury caused by oxygen-glucose deprivation/reoxygenation, probably by activating the phosphatidylinositol 3-kinase/protein kinase B signaling pathway to suppress neuronal apoptosis.