PPAR-γ Mediates Ta-VNS-Induced Angiogenesis and Subsequent Functional Recovery after Experimental Stroke in Rats

Background. Neoangiogenesis after cerebral ischemia in mammals is insufficient to restore neurological function, illustrating the need to design better strategies for improving outcomes. Our previous study has suggested that transcutaneous auricular vagus nerve stimulation (ta-VNS) induced angiogenesis and improved neurological functions in a rat model of cerebral ischemia/reperfusion (I/R) injury. However, the mechanisms involved need further exploration. Peroxisome proliferator-activated receptor-γ (PPAR-γ), well known as a ligand-modulated nuclear transcription factor, plays a crucial role in the regulation of cerebrovascular structure and function. Hence, the present study was designed to explore the role of PPAR-γ in ta-VNS-mediated angiogenesis and uncover the possible molecular mechanisms against ischemic stroke. Methods. Adult male Sprague–Dawley rats were transfected with either PPAR-γ small interfering RNA (siRNA) or lentiviral vector without siRNA prior to surgery and subsequently received ta-VNS treatment. The expression and localization of PPAR-γ in the ischemic boundary after ta-VNS treatment were examined. Subsequently, neurological deficit scores, neuronal damage, and infarct volume were all evaluated. Additionally, microvessel density, endothelial cell proliferation condition, and the expression of angiogenesis-related molecules in the peri-infarct cortex were measured. Results. We found that the expression of PPAR-γ in the peri-infarct cortex increased at 14 d and reached normal levels at 28 d after reperfusion. Ta-VNS treatment further upregulated PPAR-γ expression in the ischemic cortex. PPAR-γ was mainly expressed in neurons and astrocytes. Furthermore, ta-VNS-treated I/R rats showed better neurobehavioral recovery, alleviated neuronal injury, reduced infarct volume, and increased angiogenesis, as indicated by the elevated levels of brain-derived neurotrophic factor (BDNF), vascular endothelial growth factor (VEGF), and phosphorylated endothelial nitric oxide synthase (P-eNOS). Surprisingly, the beneficial effects of ta-VNS were weakened after PPAR-γ silencing. Conclusions. Our results suggest that PPAR-γ is a potential mediator of ta-VNS-induced angiogenesis and neuroprotection against cerebral I/R injury.

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Tetrandrine alleviates cerebral ischemia/reperfusion injury by suppressing NLRP3 inflammasome activation via Sirt-1

PeerJ ◽

10.7717/peerj.9042 ◽

2020 ◽

Vol 8 ◽

pp. e9042

Author(s):

Jun Wang ◽

Ming Guo ◽

Ruojia Ma ◽

Maolin Wu ◽

Yamei Zhang

Keyword(s):

Cerebral Ischemia ◽

Nlrp3 Inflammasome ◽

Molecular Mechanisms ◽

Infarct Volume ◽

Ischemia Reperfusion ◽

Sirtuin 1 ◽

Neurological Deficits ◽

Inflammasome Activation ◽

Cerebral Ischemia Reperfusion ◽

Nlrp3 Inflammasome Activation

Background & Aims Tetrandrine (Tet) has been reported to have anti-inflammatory effects and protect from the ischemic strokes. The NLRP3 inflammasome plays a key role in cerebral ischemia/reperfusion (I/R)-induced inflammatory lesions. However, the molecular mechanisms of Tet related to the progression of cerebral ischemia are still unclear. Therefore, the aim of this study was to investigate the possible effects of Tet on cerebral ischemia and the related mechanisms involved in NLRP3 inflammasome. Methods C57BL/6J mice used as a cerebral I/R injury model underwent middle cerebral artery occlusion (MCAO) for 2 h following reperfusion for 24 h. Tet (30 mg/kg/day, i.p.) was administered for seven days and 30 min before and after MCAO. Their brain tissues were evaluated for NLRP3 inflammasome and Sirtuin-1 (Sirt-1) expression. An intracerebroventricular injection of Sirt-1 siRNA was administered to assess the activation of the NLRP3 inflammasome. Results Tet significantly reduced the neurological deficits, infarction volume, and cerebral water content in MCAO mice. Moreover, it inhibited I/R-induced over expression of NLRP3, cleaved caspase-1, interleukin (IL)-1β, IL-18, and Sirt-1. Sirt-1 knockdown with siRNA greatly blocked the Tet-induced reduction of neurological severity score and infarct volume, and reversed the inhibition of NLRP3 inflammasome activation. Conclusion Our results demonstrate that Tet has benefits for cerebral I/R injury, which are partially related to the suppression of NLRP3 inflammasome activation via upregulating Sirt-1.

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Abstract 137: The Effect Of Mitophagy During Transient Ischemic Brain In Rats

Stroke ◽

10.1161/str.44.suppl_1.a137 ◽

2013 ◽

Vol 44 (suppl_1) ◽

Author(s):

Qiang Li ◽

Ting Zhang ◽

Jixian Wang ◽

Yongting Wang ◽

Guo-Yuan Yang ◽

...

Keyword(s):

Cerebral Ischemia ◽

Molecular Mechanisms ◽

Infarct Volume ◽

Ischemia Reperfusion ◽

Atp Synthesis ◽

Beclin 1 ◽

Neurological Deficits ◽

Ischemic Brain ◽

Pre Treatment ◽

The Impact

Background and Purpose: Mitochondria provides energy to maintain normal cell functioning. Mitophagy is one of mitochondria functions, which can clear out injured mitochondria, ensure stability of mitochondria and promote cell survival in hostile environment. However, if mitophagy occurs during cerebral ischemia is unknown. The present study explored dynamic mitophagy, the effect of promoting mitophagy, and the molecular mechanisms of mitophagy during cerebral ischemia/reperfusion. Methods: Adult male SD rats underwent 2h middle cerebral artery occlusion (MCAO) followed by 6 to 72h reperfusion. Dynamic changes of mitophagy were determined by LC3 immunostaining, Western blot analysis, and transmission electron microscope. To study the impact of mitophagy, we injected rapamycin, a mitophagy stimulator, into the left ventricle in rats underwent transient MCAO. To evaluate the effect of mitophagy, neuronal death and neurological deficits were determined. To explore the effect of mitophagy on mitochondria function, the number of mitochondria, the levels of MDA, ATP, and JC-1 were examined. To study the mechanism of mitophagy, mitochondrial Beclin-1 and p62 expression were also determined. Results: We demonstrated that autophagy was mainly detected in mitochondria in the peri-focal area of ischemic cortex after ischemia/reperfusion. Mitophagy was increased at 6h (p<0.05), peaked at 24h (p<0.05), gradually reduced at 48h (p<0.05), and returned to normal at 72h of transient MCAO. Pre-treatment with rapamycin greatly enhanced mitophagy, reduced infarct volume, and improved neurological outcomes compared to the control (p<0.05). We found that the number of mitochondria and mtDNA copy, mitochondria ATP synthesis level, and JC-1 were increased (p<0.05), and MDA was reduced in rapamycin treated rats (p<0.05). We further demonstrated that rapamycin pre-treatment enhanced mitochondrial Beclin-1and p62 in mitochondria. Conclusion: We demonstrated ischemia could induce mitophagy in brain cells. Rapamycin attenuated ischemic brain injury, which was via stimulating mitophagy that can reduce oxidative stress and improve mitochondria function. The mechanism of rapamycin promoting mitophagy was through increasing Beclin-1 and p62 expression.

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Deficiency of ROS-Activated TRPM2 Channel Protects Neurons from Cerebral Ischemia-Reperfusion Injury through Upregulating Autophagy

Oxidative Medicine and Cellular Longevity ◽

10.1155/2021/7356266 ◽

2021 ◽

Vol 2021 ◽

pp. 1-12

Author(s):

Xupang Hu ◽

Lijuan Wu ◽

Xingyu Liu ◽

Yi Zhang ◽

Min Xu ◽

...

Keyword(s):

Cerebral Ischemia ◽

Ischemia Reperfusion Injury ◽

Neuronal Damage ◽

Infarct Volume ◽

Ischemia Reperfusion ◽

Mtor Pathway ◽

Regulation Mechanism ◽

Cerebral Ischemia Reperfusion ◽

Trpm2 Channel ◽

Autophagy Activity

Cerebral ischemia-reperfusion (I-R) transiently increased autophagy by producing excessively reactive oxygen species (ROS); on the other hand, activated autophagy would remove ROS-damaged mitochondria and proteins, which led to cell survival. However, the regulation mechanism of autophagy activity during cerebral I-R is still unclear. In this study, we found that deficiency of the TRPM2 channel which is a ROS sensor significantly decreased I-R-induced neuronal damage. I-R transiently increased autophagy activity both in vitro and in vivo. More importantly, TRPM2 deficiency decreased I-R-induced neurological deficit score and infarct volume. Interestingly, our results indicated that TRPM2 deficiency could further activate AMPK rather than Beclin1 activity, suggesting that TRPM2 inhibits autophagy by regulating the AMPK/mTOR pathway in I-R. In conclusion, our study reveals that ROS-activated TRPM2 inhibits autophagy by downregulating the AMPK/mTOR pathway, which results in neuronal death induced by cerebral I-R, further supporting that TRPM2 might be a potential drug target for cerebral ischemic injury therapy.

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A20-Binding Inhibitor of NF-κB 1 Ameliorates Neuroinflammation and Mediates Antineuroinflammatory Effect of Electroacupuncture in Cerebral Ischemia/Reperfusion Rats

Evidence-based Complementary and Alternative Medicine ◽

10.1155/2020/6980398 ◽

2020 ◽

Vol 2020 ◽

pp. 1-14

Author(s):

Xueling Zhou ◽

Wenhao Lu ◽

You Wang ◽

Jiani Li ◽

Yong Luo

Keyword(s):

Cerebral Ischemia ◽

Infarct Volume ◽

Neuroprotective Effect ◽

Ischemia Reperfusion ◽

Artery Occlusion ◽

Neurological Deficits ◽

Sprague Dawley ◽

Cerebral Ischemia Reperfusion ◽

Neuroprotective Strategy

A20-binding inhibitor of NF-κB 1 (ABIN1) is an inhibitor of NF-κB and exerts anti-inflammatory effect. Electroacupuncture (EA) is considered as a neuroprotective strategy by inhibiting neuroinflammatory damage after cerebral ischemia. This study was performed to explore the role of ABIN1 and investigate whether the ABIN1 is involved in the mechanism of EA in cerebral ischemia/reperfusion (I/R) rats. Male Sprague-Dawley (SD) rats were subjected to middle cerebral artery occlusion/reperfusion (MCAO/R) and received EA after reperfusion once a day. Lentivirus-mediated ABIN1 gene knockdown was used to detect the role of ABIN1 in neuroinflammation after I/R. ABIN1 expression, proinflammatory cytokine levels, microglial activation, neurological function, infarct volumes, and NF-κB activation were assessed. ABIN1 expression was elevated in the peri-infarct cortex and was further upregulated by EA. ABIN1 knockdown increased the levels of proinflammatory cytokines and activation of microglia, worsened neurological deficits, and enlarged the infarct volume. Moreover, ABIN1 was blocked to partially reverse the neuroprotective effect of EA, and this treatment weakened the ability of EA to suppress NF-κB activity. Based on these findings, ABIN1 is a potential suppressor of neuroinflammation and ABIN1 mediates the antineuroinflammatory effect of EA in cerebral I/R rats.

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Protective Effect of Buyang Huanwu Decoction on Cerebral Ischemia Reperfusion Injury by Alleviating Autophagy in the Ischemic Penumbra

Evidence-based Complementary and Alternative Medicine ◽

10.1155/2021/9937264 ◽

2021 ◽

Vol 2021 ◽

pp. 1-13

Author(s):

Yanmeng Zhao ◽

Xiujuan Ma ◽

Wentao Yu ◽

Ziwei Zhang ◽

Wenliang Wang ◽

...

Keyword(s):

Cerebral Ischemia ◽

Protective Effect ◽

Neuronal Damage ◽

Infarct Volume ◽

Ischemia Reperfusion ◽

Beclin 1 ◽

Buyang Huanwu Decoction ◽

Apoptosis Rate ◽

The Core ◽

Cerebral Ischemia Reperfusion

Objectives. To evaluate the protective effect of Buyang Huanwu Decoction (BHD) against cerebral ischemia reperfusion and investigate whether autophagy is involved in its mechanism of action. Methods. Adult male Sprague Dawley rats were randomly divided into three groups: the sham, cerebral ischemia reperfusion (I/R), and I/R + BHD groups. A rat model of cerebral I/R injury was established via middle cerebral artery occlusion (MCAO) for 2 h, followed by 1, 3, and 7 d of reperfusion. Neurological scores and regional cerebral blood flow were assessed to determine whether the model was successfully established. Brain infarct volume was determined by 2,3,5-triphenyl tetrazolium chloride (TTC) staining. The apoptosis rate was detected using TdT-mediated dUTP Nick-End Labeling (TUNEL) staining, and neuronal damage was evaluated by Nissl staining. The Beclin-1 and LC3 protein levels in the ischemic core, penumbra, and contralateral area were analysed by Western blotting. The occurrence of autophagy in the penumbra was observed by transmission electron microscopy (TEM). Results. BHD treatment alleviated the cerebral infarct volume, neuronal apoptosis rate, and neuronal damage 3 and 7 d after cerebral I/R injury. Furthermore, 3 d after reperfusion, we observed that the Beclin-1 levels were significantly decreased in the core in the I/R group, whereas transformation of LC3 I to LC3 II exhibited no obvious differences between the sham and I/R groups. In the penumbra, the Beclin-1 levels and transformation of LC3 I to LC3 II in the I/R group were significantly increased compared with that in the sham group. However, no significant difference in the contralateral area was noted between the two groups. BHD significantly inhibited the expression of Beclin-1 and the transformation of LC3 I to LC3 II in the penumbra after cerebral I/R injury but yielded no significant changes in the core and contralateral area. Conclusions. BHD exerts a neuroprotective effect by inhibiting autophagy in neurons in the penumbra after cerebral I/R injury.

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Rapamycin Pretreatment Alleviates Cerebral Ischemia/Reperfusion Injury in Dose-Response Manner Through Inhibition of the Autophagy and NFκB Pathways in Rats

Dose-Response ◽

10.1177/1559325820946194 ◽

2020 ◽

Vol 18 (3) ◽

pp. 155932582094619

Author(s):

Liru Li ◽

Jie Huang

Keyword(s):

Cerebral Ischemia ◽

Molecular Mechanisms ◽

Ischemia Reperfusion Injury ◽

Focal Cerebral Ischemia ◽

Ischemia Reperfusion ◽

Vehicle Group ◽

Sprague Dawley ◽

Triphenyltetrazolium Chloride ◽

Cerebral Ischemia Reperfusion ◽

Y Maze

Although rapamycin can attenuate cerebral ischemia/reperfusion (I/R) injury, the potential roles of rapamycin on cerebral I/R injury remain largely controversial. The present work aims to evaluate underlying molecular mechanisms of rapamycin pretreatment on I/R injury. In total, 34 Sprague-Dawley rats were randomly grouped to 3 groups: sham group (n = 2), vehicle group (n = 16), and rapamycin-pretreatment group (n = 16). Before the focal cerebral ischemia was induced, those rats in the pretreatment group were intraperitoneally injected rapamycin (1 mg/kg body) for 20 hours, while rats in the vehicle group received same-volume saline. Then, rats in these 2 groups received focal cerebral ischemia for 3 and 6 hours, respectively (n = 8 in each group), which was followed by the application of reperfusion for 4, 24, 72 hours, and 1 week (n = 2 in each group). The results showed that the rapamycin pretreatment improved the memory functions of rats after I/R injury, which was evaluated using a Y-maze test. Rapamycin pretreatment significantly reduced the size of triphenyltetrazolium chloride infarction and decreased the expression of I/R injury markers. Moreover, the expression of LC-3 and NFκB was also significantly reduced after rapamycin pretreatment. Taken together, rapamycin pretreatment may alleviate cerebral I/R injury partly through inhibiting autophagic activities and NFκB pathways in rats.

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Deficiency of Myeloperoxidase Increases Infarct Volume and Nitrotyrosine Formation in Mouse Brain

Journal of Cerebral Blood Flow & Metabolism ◽

10.1097/00004647-200201000-00006 ◽

2002 ◽

Vol 22 (1) ◽

pp. 50-54 ◽

Cited By ~ 40

Author(s):

Shunya Takizawa ◽

Yasuaki Aratani ◽

Naoto Fukuyama ◽

Nobuyo Maeda ◽

Hisayuki Hirabayashi ◽

...

Keyword(s):

Cerebral Ischemia ◽

Neuronal Damage ◽

Infarct Volume ◽

Ischemia Reperfusion ◽

Enzyme Inactivation ◽

Wild Type ◽

Cerebral Ischemia Reperfusion ◽

Deficient Mice

Peroxynitrite is responsible for nitration in vivo, whereas myeloperoxidase can also catalyze protein nitration in the presence of high NO2− levels. Recent reports of myeloperoxidase-mediated enzyme inactivation or lipid peroxidation have suggested a role of myeloperoxidase in various pathological conditions. To clarify the role of myeloperoxidase in ischemic brain injury, the authors measured nitrotyrosine formation and infarct volume in myeloperoxidase-deficient or wild-type mice subjected to 2-hour focal cerebral ischemia-reperfusion. Twenty-four hours after reperfusion, infarct volume was significantly larger in myeloperoxidase-deficient mice than in wild-type mice (81 ± 20 mm3 vs. 52 ± 13 mm3, P < 0.01), and nitrotyrosine levels in the infarct region were higher in myeloperoxidase-deficient mice than in wild-type mice (13.4 ± 6.1 μg/mg vs. 9.8 ± 4.4 μg/mg, P = 0.13). Fourteen hours after reperfusion, the nitrotyrosine level was significantly higher in myeloperoxidase-deficient mice than in wild-type mice (3.3 ± 2.9 μg/mg vs. 1.4 ± 0.4 μg/mg, P < 0.05). The authors conclude that the absence of myeloperoxidase increases ischemic neuronal damage in vivo, and that the myeloperoxidase-mediated pathway is not responsible for the nitration reaction in cerebral ischemia-reperfusion.

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Neuroprotective Effect of Daidzein Extracted From Pueraria lobate Radix in a Stroke Model Via the Akt/mTOR/BDNF Channel

Frontiers in Pharmacology ◽

10.3389/fphar.2021.772485 ◽

2022 ◽

Vol 12 ◽

Author(s):

Meizhu Zheng ◽

Mi Zhou ◽

Minghui Chen ◽

Yao Lu ◽

Dongfang Shi ◽

...

Keyword(s):

Caspase 3 ◽

Neuronal Damage ◽

Infarct Volume ◽

Neuroprotective Effect ◽

Ischemia Reperfusion ◽

Neurological Deficits ◽

Experimental Stroke ◽

Stroke Model ◽

Mtor Signaling Pathway ◽

Therapeutic Research

Daidzein is a plant isoflavonoid primarily isolated from Pueraria lobate Radix as the dry root of P. lobata (Wild.) Ohwi, have long been used as nutraceutical and medicinal herb in China. Despite the report that daidzein can prevent neuronal damage and improve outcome in experimental stroke, the mechanisms of this neuroprotective action have been not fully elucidated. The aim of this study was to determine whether the daidzein elicits beneficial actions in a stroke model, namely, cerebral ischemia/reperfusion (I/R) injury, and to reveal the underlying neuroprotective mechanisms associated with the regulation of Akt/mTOR/BDNF signal pathway. The results showed that I/R, daidzein treatment significantly improved neurological deficits, infarct volume, and brain edema at 20 and 30 mg/kg, respectively. Meanwhile, it was found out that the pretreatment with daidzein at 20 and 30 mg/kg evidently improved striatal dopamine and its metabolite levels. In addition, daidzein treatment reduced the cleaved Caspase-3 level but enhanced the phosphorylation of Akt, BAD and mTOR. Moreover, daidzein at 30 mg/kg treatment enhanced the expression of BDNF and CREB significantly. This protective effect of daidzein was ameliorated by inhibiting the PI3K/Akt/mTOR signaling pathway using LY294002. To sum up, our results demonstrated that daidzein could protect animals against ischemic damage through the regulation of the Akt/mTOR/BDNF channel, and the present study may facilitate the therapeutic research of stroke.

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Surface-modified engineered exosomes attenuated cerebral ischemia/reperfusion injury by targeting the delivery of quercetin towards impaired neurons

Journal of Nanobiotechnology ◽

10.1186/s12951-021-00879-4 ◽

2021 ◽

Vol 19 (1) ◽

Author(s):

Lin Guo ◽

Zhixuan Huang ◽

Lijuan Huang ◽

Jia Liang ◽

Peng Wang ◽

...

Keyword(s):

Cerebral Ischemia ◽

Reperfusion Injury ◽

Targeted Delivery ◽

Ischemia Reperfusion Injury ◽

Infarct Volume ◽

Ischemia Reperfusion ◽

Artery Occlusion ◽

Therapeutic Drug ◽

Cerebral Ischemia Reperfusion ◽

Cerebral Ischemia Reperfusion Injury

Abstract Background The incidence of ischemic stroke in the context of vascular disease is high, and the expression of growth-associated protein-43 (GAP43) increases when neurons are damaged or stimulated, especially in a rat model of middle cerebral artery occlusion/reperfusion (MCAO/R). Experimental design We bioengineered neuron-targeting exosomes (Exo) conjugated to a monoclonal antibody against GAP43 (mAb GAP43) to promote the targeted delivery of quercetin (Que) to ischemic neurons with high GAP43 expression and investigated the ability of Exo to treat cerebral ischemia by scavenging reactive oxygen species (ROS). Results Our results suggested that Que loaded mAb GAP43 conjugated exosomes (Que/mAb GAP43-Exo) can specifically target damaged neurons through the interaction between Exo-delivered mAb GAP43 and GAP43 expressed in damaged neurons and improve survival of neurons by inhibiting ROS production through the activation of the Nrf2/HO-1 pathway. The brain infarct volume is smaller, and neurological recovery is more markedly improved following Que/mAb GAP43-Exo treatment than following free Que or Que-carrying exosome (Que-Exo) treatment in a rat induced by MCAO/R. Conclusions Que/mAb GAP43-Exo may serve a promising dual targeting and therapeutic drug delivery system for alleviating cerebral ischemia/reperfusion injury.

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