ginsenoside-rd and Ischemic-Attack--Transient

To investigate the effects of ginsenoside Rd (Rd) on neurogenesis in rat brain after ischemia/reperfusion injury (IRI).. Male SD rats were subjected to transient middle cerebral artery occlusion (MCAO) followed by reperfusion. The rats were injected with Rd (1, 2.5, and 5 mg·kg(-1)·d(-1), ip) from d 1 to d 3 after MCAO, and with BrdU (50 mg·kg(-1)·d(-1), ip) from d 3 to d 6, then sacrificed on 7 d. The infarct size and neurological scores were assessed. Neurogenesis in the brains was detected by BrdU, DCX, Nestin, and GFAP immunohistochemistry staining. PC12 cells subjected to OGD/reperfusion were used as an in vitro model of brain ischemia. VEGF and BDNF levels were assessed with ELISA, and Akt and ERK phosphorylation was measured using Western blotting.. Rd administration dose-dependently decreased the infarct size and neurological scores in the rats with IRI. The high dose of Rd 5 (mg·kg(-1)·d(-1)) significantly increased Akt phosphorylation in ipsilateral hemisphere, and markedly increased the number of BrdU/DCX and Nestin/GFAP double-positive cells in ischemic area, which was partially blocked by co-administration of the PI3 kinase inhibitor LY294002. Treatment with Rd (25, 50, and 100 μmol/L) during reperfusion significantly increased the expression of VEGF and BDNF in PC12 cells with IRI. Furthermore, treatment with Rd dose-dependently increased the phosphorylation of Akt and ERK, and significantly decreased PC12 cell apoptosis, which were blocked by co-application of LY294002.. Rd not only attenuates ischemia/reperfusion injury in rat brain, but also promotes neurogenesis via increasing VEGF and BDNF expression and activating the PI3K/Akt and ERK1/2 pathways.

Topics: Animals; Brain; Brain-Derived Neurotrophic Factor; Doublecortin Protein; Ginsenosides; Infarction, Middle Cerebral Artery; Ischemic Attack, Transient; Male; MAP Kinase Signaling System; Neurogenesis; Panax; Phosphatidylinositol 3-Kinases; Proto-Oncogene Proteins c-akt; Rats; Rats, Sprague-Dawley; Reperfusion Injury; Signal Transduction; Vascular Endothelial Growth Factor A

Phosphorylated tau was found to be regulated after cerebral ischemia and linked to high risk for the development of post-stroke dementia. Our previous study showed that ginsenoside Rd (Rd), one of the main active ingredients in Panax ginseng, decreased tau phosphorylation in Alzheimer model. As an extending study, here we investigated whether Rd could reduce tau phosphorylation and sequential cognition impairment after ischemic stroke. Sprague-Dawley rats were subjected to focal cerebral ischemia. The tau phosphorylation of rat brains were analyzed following ischemia by Western blot and animal cognitive functions were examined by Morris water maze and Novel object recognition task. Ischemic insults increased the levels of phosphorylated tau protein at Ser199/202 and PHF-1 sites and caused animal memory deficits. Rd treatment attenuated ischemia-induced enhancement of tau phosphorylation and ameliorated behavior impairment. Furthermore, we revealed that Rd inhibited the activity of Glycogen synthase kinase-3β (GSK-3β), the most important kinase involving tau phosphorylation, but enhanced the activity of protein kinase B (PKB/AKT), a key kinase suppressing GSK-3β activity. Moreover, we found that LY294002, an antagonist for phosphatidylinositol 3-kinase (PI3K)/AKT signaling pathway, abolished the inhibitory effect of Rd on GSK-3β activity and tau phosphorylation. Taken together, our findings provide the first evidence that Rd may reduce cerebral ischemia-induced tau phosphorylation via the PI3K/AKT/GSK-3β pathway.

Topics: Animals; Ginsenosides; Glycogen Synthase Kinase 3; Glycogen Synthase Kinase 3 beta; Ischemic Attack, Transient; Male; Oncogene Protein v-akt; Panax; Phosphatidylinositol 3-Kinases; Phosphorylation; Prosencephalon; Rats; Rats, Sprague-Dawley; tau Proteins

We previously found that ginsenoside Rd (Rd), one of the major active ingredients in Panax ginseng, protects neuronal cells from hydrogen peroxide and oxygen-glucose deprivation, an in vitro model of cerebral ischemia. In this study, we examined the protective effects of Rd in an animal model of focal cerebral ischemia. Rats administered with Rd or vehicle were subjected to transient middle cerebral artery occlusion (MCAO). Rd (50 mg/kg) significantly reduced the infarct volume by 52.8%. This reduction of injury volume was associated with an improvement in neurological function and was sustained for at least 2 weeks after the induction of ischemia. To evaluate the underlying mechanisms of Rd against stroke, brain tissues were assayed for mitochondrial enzyme activities, mitochondrial membrane potential (MMP), production of reactive oxygen species (ROS), energy metabolites, and apoptosis. Rd markedly protected mitochondria as indicated by preserved respiratory chain complex activities and aconitase activity, lowered mitochondrial hydrogen peroxide production, and hyperpolarized MMP. Microdialysis results illustrated that Rd significantly decreased the accumulation of lactate, the end product of anaerobic glycolysis, and increased pyruvate, the end product of aerobic glycolysis, hence inducing a lower lactate/pyruvate ratio. Additionally, in vitro studies further exhibited that Rd protected isolated mitochondria from calcium-induced damage by attenuating mitochondrial swelling, preserving MMP and decreasing ROS production. Moreover, Rd treatment reduced mitochondrial release of cytochrome c (CytoC) and apoptosis-inducing factor (AIF), thereby minimizing mitochondria-mediated apoptosis following ischemia. In conclusion, these findings demonstrated that Rd exerts neuroprotective effects in transient focal ischemia, which may involve an integrated process of the mitochondrial protection, energy restoration and inhibition of apoptosis.

Topics: Aconitate Hydratase; Animals; Apoptosis; Brain; Calcium; Electron Transport; Ginsenosides; Glucose; Hippocampus; Infarction, Middle Cerebral Artery; Ischemic Attack, Transient; Lactic Acid; Male; Membrane Potential, Mitochondrial; Mitochondria; Mitochondrial Swelling; Neuroprotective Agents; Pyruvic Acid; Rats; Rats, Sprague-Dawley; Reactive Oxygen Species