Protective effect of tetraethyl pyrazine against focal cerebral ischemia/reperfusion injury in rats: Therapeutic time window and its mechanism
ABSTRACT Tetramethyl pyrazine has been considered an effective agent in treating neurons ischemia/reperfusion injury, but the mechanism of its therapeutic effect remains unclear. This study was to explore the therapeutic time window and mechanism of tetramethyl pyrazine on temporary focal cerebral ischemia/reperfusion injury.
Middle cerebral artery occlusion was conducted in male Sprague-Dawley rats and 20 mg/kg of tetramethyl pyrazine was intraperitoneally injected at different time points. At 72 h after reperfusion, all animals' neurologic deficit scores were evaluated. Cerebrums were removed and cerebral infarction volume was measured. The expression of thioredoxin and thioredoxin reductase mRNA was determined at 6 and 24 h after reperfusion.
Cerebral infarction volume and neurological deficit scores were significantly decreased in the group with tetramethyl pyrazine treatment. The expression of thioredoxin-1/thioredoxin-2 and thioredoxin reductase-1/thioredoxin reductase-2 was significantly decreased in rats with ischemia/reperfusion injury, while it was increased by tetramethyl pyrazine administration.
Treatment with tetramethyl pyrazine, within 4 h after reperfusion, protects the brain from ischemic reperfusion injury in rats. The neuroprotective mechanism of tetramethyl pyrazine treatment is, in part, mediated through the upregulation of thioredoxin transcription.
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ABSTRACT: Oxidative damage and apoptosis are critical factors contributing to neuronal death during a stroke. The aim of the present study was to evaluate the neuroprotective effects of Senkyunolide I (SEI) on focal cerebral ischemia-reperfusion (I/R) injury in rats, and investigate the underlying mechanisms. Male Sprague-Dawley rats were subjected to transient middle cerebral artery occlusion (tMCAO) for 2h, followed by 24h reperfusion, and then randomly assigned into four groups: Sham (sham-operated), Vehicle (tMCAO +normal saline), SEI-L (tMCAO +SEI 36mg/kg) and SEI-H (tMCAO +SEI 72mg/kg) groups. SEI was administered intravenously, 15min after occlusion. Neurological deficit, brain edema and infarct volume were detected after 24h of reperfusion. Histological structures of cortices and hippocampus were observed by hematoxylin and eosin staining. Biochemical indexes in the cortex were assayed by colorimetry. The impact of SEI on the Nrf2-ARE-interaction was assayed using a luciferase reporter gene. Western blotting was performed to analysis the expressions of proteins related to anti-oxidation and apoptosis. SEI administration significantly ameliorated the neurological deficit, reduced the infarct volume and brain edema, reversed the cerebral morphologic damage, decreased the levels of MDA and increased the activities of superoxide dismutase. Furthermore, the high dose SEI could significantly activate the Nrf2/ARE pathway by up-regulating the phosphorylation of Erk1/2 and inducing Nrf2 nuclear translocation with enhanced HO-1 and NQO1 expressions. Additionally, treatment with SEI remarkably promoted the ratio of Bcl-2/Bax and inhibited the expressions of cleaved caspase 3 and caspase 9. These results suggest that the neuroprotective mechanisms of SEI are associated with its anti-oxidation and anti-apoptosis properties. Copyright © 2015. Published by Elsevier B.V.Brain Research 02/2015; 1605. DOI:10.1016/j.brainres.2015.02.015
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ABSTRACT: CXC195 showed strongest protective effects among the ligustrazine derivatives in cells and prevented apoptosis induced by H2O2 injury. We recently demonstrated that CXC195 protected against cerebral ischemia/reperfusion (I/R) injury by its antioxidant activity. However, whether the anti-apoptotic action of CXC195 is involved in cerebral I/R injury is unknown. Here, we investigated the role of CXC195 in apoptotic processes induced by cerebral I/R and the possible signaling pathways. Male Wistar rats were submitted to transient middle cerebral artery occlusion for 2 h, followed by 24 h reperfusion. CXC195 was injected intraperitoneally at 2 h and 12 h after the onset of ischemia. The number of apoptotic cells was measured by TUNEL assay, apoptosis-related protein cleaved caspase-3, Bcl-2, Bax and the phosphorylation levels of Akt and GSK3β in ischemic penumbra were assayed by western blot. The results showed that administration of CXC195 at the doses of 3 mg/kg and 10 mg/kg significantly inhibited the apoptosis by decreasing the number of apoptotic cells, decreasing the level of cleaved caspase-3 and Bax, and increasing the level of Bcl-2 in rats subjected to I/R injury. Simultaneously, CXC195 treatment markedly increased the phosphorylation of Akt and GSK3β. Blockade of PI3K activity by wortmannin, dramatically abolished its anti-apoptotic effect and lowered both Akt and GSK3β phosphorylation levels. Our study firstly demonstrated that CXC195 protected against cerebral I/R injury by reducing apoptosis in vivo and PI3K/Akt/GSK3β pathway involved in the anti-apoptotic effect.Neurochemistry International 01/2014; DOI:10.1016/j.neuint.2014.01.006
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ABSTRACT: A novel tetramethylpyrazine derivative, CXC195, has been recently shown to protect against cerebral ischemia-reperfusion (I/R) injury. However, the detailed mechanisms underlying the neuroprotection of CXC195 are still unclear. The aim of the present study was to investigate the effects of CXC195 on the phosphorylation of endothelial nitric oxide synthase (eNOS) in response to cerebral I/R and to determine whether phosphatidylinositol-3-kinase (PI3K)/Akt signaling pathway might be involved. An in vitro model of oxygen glucose deprivation (OGD) which was performed on primary cultured human aortic endothelial cells (HAECs) and an in vivo middle cerebral artery occlusion (MCAO) model that was performed on Wistar rats were used in this study. CXC195 increased nitric oxide (NO) production and the phosphorylation but not the protein level of eNOS in HAECs subjected to 1 h OGD followed by reperfusion. In addition, CXC195 increased the phosphorylation of Akt; inhibition of PI3K/Akt pathway by a specific inhibitor, wortmannin, suppressed CXC195-induced NO release in HAECs. Consistently, CXC195 treatment significantly restored the phosphorylations of eNOS and Akt in the cortical penumbra of rats subjected to 2 h MCAO followed by reperfusion. Moreover, wortmannin abolished CXC195-induced eNOS phosphorylation and neuroprotection as evidenced by a reversal of the reduction in infarct volume and neurobehavioral outcomes. In conclusion, CXC195 induced phosphorylation of eNOS by activation of PI3K/Akt signaling under pathological cerebral I/R conditions, which provided a novel explanation for the neuroprotective effect of CXC195.Neurochemical Research 11/2014; DOI:10.1007/s11064-014-1485-x