Electroacupuncture Inhibits Neuronal Autophagy and Apoptosis via the PI3K/AKT Pathway Following Ischemic Stroke

Electroacupuncture Pretreatment Alleviates Cerebral Ischemia-Reperfusion Injury by Regulating Mitophagy via mTOR-ULK1/FUNDC1 Axis in Rats

OBJECTIVE

Electroacupuncture (EA) pretreatment has been shown to alleviate cerebral ischemia-reperfusion (I/R) injury; however, the underlying mechanism remains unclear. To investigate the involvement of mTOR signaling in the protective role of EA in I/R-induced brain damage and mitochondrial injury.

METHODS

Sprague-Dawley male rats were pretreated with vehicle, EA (at Baihui and Shuigou acupoints), or rapamycin + EA for 30 min daily for 5 consecutive days, followed by the middle cerebral artery occlusion to induce I/R injury. The neurological functions of the rats were assessed using the Longa neurological deficit scores. The rats were sacrificed immediately after neurological function assessment. The brains were obtained for the measurements of cerebral infarct area. The mitochondrial structural alterations were observed under transmission electron microscopy. The mitochondrial membrane potential changes were detected by JC-1 staining. The alterations in autophagy-related protein expression were examined using Western blot analysis.

RESULTS

Compared with untreated I/R rats, EA-pretreated rats exhibited significantly decreased neurological deficit scores and cerebral infarct volumes. EA pretreatment also reversed I/R-induced mitochondrial structural abnormalities and loss of mitochondrial membrane potential. Furthermore, EA pretreatment downregulated the protein expression of LC3-II, p-ULK1, and FUNDC1 while upregulating the protein expression of p-mTORC1 and LC3-I. Rapamycin effectively blocked the above-mentioned effects of EA.

CONCLUSION

EA pretreatment at Baihui and Shuigou alleviates cerebral I/R injury and mitochondrial impairment in rats through activating the mTORC1 signaling. The suppression of autophagy-related p-ULK1/FUNDC1 pathway is involved in the neuroprotective effects of EA.

Hypoxia Tolerant Species: The Wisdom of Nature Translated into Targets for Stroke Therapy

Human neurons rapidly die after ischemia and current therapies for stroke management are limited to restoration of blood flow to prevent further brain damage. Thrombolytics and mechanical thrombectomy are the available reperfusion treatments, but most of the patients remain untreated. Neuroprotective therapies focused on treating the pathogenic cascade of the disease have widely failed. However, many animal species demonstrate that neurons can survive the lack of oxygen for extended periods of time. Here, we reviewed the physiological and molecular pathways inherent to tolerant species that have been described to contribute to hypoxia tolerance. Among them, Foxo3 and Eif5A were reported to mediate anoxic survival in Drosophila and Caenorhabditis elegans, respectively, and those results were confirmed in experimental models of stroke. In humans however, the multiple mechanisms involved in brain cell death after a stroke causes translation difficulties to arise making necessary a timely and coordinated control of the pathological changes. We propose here that, if we were able to plagiarize such natural hypoxia tolerance through drugs combined in a pharmacological cocktail it would open new therapeutic opportunities for stroke and likely, for other hypoxic conditions.

Ibrutinib ameliorates cerebral ischemia/reperfusion injury through autophagy activation and PI3K/Akt/mTOR signaling pathway in diabetic mice

Bruton’s tyrosine kinase (BTK) is involved in the diabetogenic process and cerebral ischemic injury. However, it remained unclear whether BTK inhibition has remedial effects on ischemia/reperfusion (I/R) injury complicated with diabetes. We aim to investigate the regulatory role and potential mechanism of ibrutinib, a selective inhibitor of BTK, in cerebral I/R injured diabetic mice. The cytotoxicity and cell vitality tests were performed to evaluate the toxic and protective effects of ibrutinib at different incubating concentrations on normal PC12 cells or which were exposed to high glucose for 24 h, followed by hypoxia and reoxygenation (H/R), respectively. Streptozotocin (STZ) stimulation-induced diabetic mice were subjected to 1 h ischemia and then reperfusion. Then the diabetic mice received different dosages of ibrutinib or vehicle immediately and 24 h after the middle cerebral artery occlusion (MCAO). The behavioral, histopathological, and molecular biological tests were then performed to demonstrate the neuroprotective effects and mechanism in I/R injured diabetic mice. Consequently, Ibrutinib improved the decreased cell viability and attenuated oxidative stress in the high glucose incubated PC12 cells which subjected to H/R injury. In the I/R injured diabetic mice, ibrutinib reduced the cerebral infarct volume, improved neurological deficits, ameliorated pathological changes, and improved autophagy in a slightly dose-dependent manner. Furthermore, the expression of PI3K/AKT/mTOR pathway-related proteins were significantly upregulated by ibrutinib treatment. In summary, our finding collectively demonstrated that Ibrutinib could effectively ameliorate cerebral ischemia/reperfusion injury via ameliorating inflammatory response, oxidative stress, and improving autophagy through PI3K/Akt/mTOR signaling pathway in diabetic mice.

Electroacupuncture Inhibits Myelin Sheath Injury in the Internal Capsule After Focal Cerebral Infarction in Rats Through the Nogo-A/NgR Signaling Pathway

BACKGROUND Ischemic stroke is usually accompanied by white matter damage. The effect of electroacupuncture (EA) on ameliorating white matter damage is still unclear. The purpose of this study was to explore the precise mechanism of EA in treating ischemic white matter. MATERIAL AND METHODS In this study, 40 Sprague-Dawley rats were randomly divided into 4 groups: normal group, the sham-operated group, model group, and EA group. The stroke model was established by right middle cerebral artery occlusion, and EA was performed 24 h after the operation for 30 min per day. After 14 days of treatment, brain tissue samples were collected. Hematoxylin and eosin and Luxol fast blue staining were used to observe the changes of white matter damage in the internal capsule (IC). The expression levels of myelin basic protein (MBP), Nogo-A, and Nogo-A receptor (NgR) were detected by immunohistochemistry and western blot. RESULTS Compared with the sham-operated group, the model group had decreased expression of MBP and significantly increased expression of Nogo-A and NgR (P<0.05). Compared with the model group, the IC damage was alleviated in the EA group. Immunohistochemistry and western blot analysis showed that EA significantly increased the expression of MBP in white matter (P<0.05) and downregulated the expression levels of Nogo-A and NgR (P<0.05). CONCLUSIONS The results of this study indicate that EA can inhibit the expression of Nogo-A/NgR and promote myelin sheath regeneration.

Neferine Protects Against Brain Damage in Permanent Cerebral Ischemic Rat Associated with Autophagy Suppression and AMPK/mTOR Regulation

Neferine is the major alkaloid compound isolated from the seed embryos of lotus. Neferine has many pharmacological effects, such as anti-inflammatory, antioxidative stress, and antiapoptotic effects, and it maintains autophagic balance. The purpose of this study was to explore the mechanism by which neferine attenuates autophagy after permanent cerebral ischemia in rats. We performed permanent cerebral ischemia in rats by middle cerebral artery occlusion (pMCAO) for 12 h with or without administration of neferine or nimodipine, a calcium (Ca²⁺) channel blocker. Neuroprotective effects were determined by evaluating the infarct volume and neurological deficits. Autophagy and its signaling pathway were determined by evaluating the expression of phosphorylated AMP-activated protein kinase alpha (AMPKα), phosphorylated mammalian target of rapamycin (mTOR), beclin-1, microtubule-associated protein 1A/1B-light chain 3 class II (LC3-II), and p62 by western blotting. Autophagosomes were evaluated by transmission electron microscopy. Neferine treatment significantly reduced infarct volumes and improved neurological deficits. Neferine significantly attenuated the upregulation of autophagy-associated proteins such as LC3-II, beclin-1, and p62 as well as autophagosome formation, all of which were induced by pMCAO. Neferine exerted remarkable protection against cerebral ischemia, possibly via the regulation of autophagy mediated by the Ca²⁺-dependent AMPK/mTOR pathway.

Targeting autophagy in ischemic stroke: From molecular mechanisms to clinical therapeutics

Stroke constitutes the second leading cause of death and a major cause of disability worldwide. Stroke is normally classified as either ischemic or hemorrhagic stroke (HS) although 87% of cases belong to ischemic nature. Approximately 700,000 individuals suffer an ischemic stroke (IS) in the US each year. Recent evidence has denoted a rather pivotal role for defective macroautophagy/autophagy in the pathogenesis of IS. Cellular response to stroke includes autophagy as an adaptive mechanism that alleviates cellular stresses by removing long-lived or damaged organelles, protein aggregates, and surplus cellular components via the autophagosome-lysosomal degradation process. In this context, autophagy functions as an essential cellular process to maintain cellular homeostasis and organismal survival. However, unchecked or excessive induction of autophagy has been perceived to be detrimental and its contribution to neuronal cell death remains largely unknown. In this review, we will summarize the role of autophagy in IS, and discuss potential strategies, particularly, employment of natural compounds for IS treatment through manipulation of autophagy.

A Network Pharmacology Approach for Exploring the Mechanisms of Panax notoginseng Saponins in Ischaemic Stroke

BACKGROUND

Panax notoginseng saponins (PNS) have been deemed effective herb compounds for treating ischaemic stroke (IS) and improving the quality of life of IS patients. This study aimed to investigate the underlying mechanisms of PNS in the treatment of IS based on network pharmacology.

METHODS

PNS were identified from the Traditional Chinese Medicine System Pharmacology (TCMSP) database, and their possible targets were predicted using the PharmMapper database. IS-related targets were identified from the GeneCards database, OMIM database, and DisGeNET database. A herb-compound-target-disease network was constructed using Cytoscape, and protein-protein interaction (PPI) networks were established with STRING. GO enrichment and KEGG pathway analysis were performed using DAVID. The binding of the compounds and key targets was validated by molecular docking studies using AutoDock Vina. The neuroprotective effect of TFCJ was substantiated in terms of oxidative stress (superoxide dismutase, glutathione peroxidase, catalase, and malondialdehyde) and the levels of IGF1/PI3K/Akt pathway proteins.

RESULTS

A total of 375 PNS targets and 5111 IS-related targets were identified. Among these targets, 241 were common to PNS, and IS network analysis showed that MAPK1, AKT1, PIK3R1, SRC, MAPK8, EGFR, IGF1, HRAS, RHOA, and HSP90AA1 are key targets of PNS against IS. Furthermore, GO and KEGG enrichment analysis indicated that PNS probably exert therapeutic effects against IS by regulating many pathways, such as the Ras, oestrogen, FoxO, prolactin, Rap1, PI3K-Akt, insulin, PPAR, and thyroid hormone signalling pathways. Molecular docking studies further corroborated the experimental results.The network pharmacology results were further verified by molecular docking and in vivo experiments.

CONCLUSIONS

The ameliorative effects of PNS against IS were predicted to be associated with the regulation of the IGF1-PI3K-Akt signalling pathway. Ginsenoside Re and ginsenoside Rb1 may play an important role in the treatment of IS.

Investigating the Pharmacological Mechanisms of SheXiang XinTongNing Against Coronary Heart Disease Based on Network Pharmacology and Experimental Evaluation

SheXiang XinTongNing (XTN), which is composed of six traditional Chinese herbs, is a commercially available Chinese patent medicine that has been widely used as the treatment of coronary heart disease (CHD). Its mechanisms against coronary heart disease, however, remain largely unknown. This study aimed to investigate the pharmacological mechanisms of XTN against CHD via network pharmacology and experimental evaluation. In this study, GO enrichment and KEGG pathway enrichment were firstly performed for acquiring the potentially active constituents of XTN, the candidate targets related to coronary heart disease, the drug-components-targets network as well as the protein-protein interaction network and further predicting the mechanisms of XTN against coronary heart disease. Subsequently, a series of in vitro experiments, specifically MTT assay, flow cytometry and Real-time quantitative polymerase chain reaction analysis, and a succession of in vivo experiments, including Tunel staining and immunohistochemical staining were conducted for further verification. Results showed that Bcl-2, IGF1, CASP3 were the key candidate targets which significantly associated with multiple pathways, namely PI3K-Akt signaling pathway and MAPK signaling pathway. It indicated that the potential mechanism of XTN against CHD may be predominantly associated with cell apoptosis. The in vitro experimental results showed that XTN treatment remarkably decreased the apoptotic rate and Bax/Bcl-2 ratio of H9c2 cells. Histological results confirmed that XTN not only effectively alleviated oxidative damage caused by myocardial ischemia but inhibited cell apoptosis. Given the above, through the combined utilization of virtual screening and experimental verification, the findings suggest that XTN makes a significant contribution in protecting the heart from oxidative stress via regulating apoptosis pathways, which lays the foundations and offers an innovative idea for future research.

Melatonin Protects Against Ischemic Brain Injury by Modulating PI3K/AKT Signaling Pathway via Suppression of PTEN Activity

Stroke is one of the leading causes of death and disability worldwide with limited therapeutic options. Melatonin can attenuate ischemic brain damage with improved functional outcomes. However, the cellular mechanisms of melatonin-driven neuroprotection against post-stroke neuronal death remain unknown. Here, distal middle cerebral artery occlusion (dMCAO) was performed in C57BL/6j mice to develop an ischemic stroke in vivo model. Melatonin was injected intraperitoneally immediately after ischemia, and 24 and 48 hours later. Melatonin treatment, with 5 to 20 mg/kg, elicited a dose-dependent decrease in infarct volume and concomitant increase in sensorimotor function. At the molecular level, phosphorylation of PTEN and Akt were increased, whereas PTEN activity was decreased in melatonin treated animals 72 hours after dMCAO. At the cellular level, oxygenglucose deprivation (OGD) challenge of neuronal cell line Neuro-2a (N2a) and primary neurons supported melatonin’s direct protection against neuronal cell death. Melatonin treatment reduced LDH release and neuronal apoptosis at various time points, markedly increased Akt phosphorylation in neuronal membrane, but significantly suppressed it in the cytoplasm of post-OGD neurons. Mechanistically, melatonin-induced Akt phosphorylation and neuronal survival was blocked by Wortmannin, a potent PIP3 inhibitor, exposing increased PI3K/Akt activation as a central player in melatonin-driven neuroprotection. Finally, PTEN knock-down through siRNA significantly inhibited PI3K/Akt activation and cell survival following melatonin treatment, suggesting that melatonin protection against ischemic brain damage, is at least partially, dependent on modulation of the PTEN/PI3K/Akt signaling axis.

Combination of Electroacupuncture and Constraint-Induced Movement Therapy Enhances Functional Recovery After Ischemic Stroke in Rats

Both electroacupuncture and constraint-induced movement therapy have been reported to produce therapeutic effects on the recovery of ischemic stroke. The combined use of these two therapies is not rare clinically, although its effectiveness is not yet clear. We aimed to evaluate the efficacy of the combination of electroacupuncture and constraint-induced movement therapy in ischemic stroke rats, and to explore the potential molecular mechanisms. Ischemic stroke rat models were established by middle cerebral artery occlusion. Then, the rats were assigned to receive one of the following interventions: sole electroacupuncture, sole constraint-induced movement therapy, the combination of both therapies, and no treatment. Functional recovery was assessed with the beam balance test and rotarod test. The infarct volume of the brain and the expression of the molecules Nogo-A, P75^NTR, NGF, BDNF, and VEGF in the brain tissue were investigated. The results demonstrated that the combination of the two therapies significantly improved neurological functional recovery in ischemic stroke rats compared to each therapy alone (P < 0.01). We also observed a significant decrease in infarct volume in rats receiving the combined treatment. Nogo-A and P75^NTR were downregulated and NGF, BDNF, and VEGF were upregulated in the combined treatment rats compared to the control rats. In conclusion, the combination of electroacupuncture and constraint-induced movement therapy enhanced functional recovery after ischemic stroke in rats, and it is a promising treatment strategy in the rehabilitation of stroke. The anti-Nogo-A effect of electroacupuncture may explain its good compatibility with CIMT in ischemic stroke rats.

Electroacupuncture Ameliorates Cerebral Ischemic Injury by Inhibiting Ferroptosis

Background: Our previous study found that electroacupuncture (EA) can promote the recovery of neurological functions, reduce the volume of cerebral infarction, and protect the neurovascular unit in middle cerebral artery occlusion (MCAO) rats. Some studies have shown that ferroptosis is closely related to ischemic stroke; however, whether EA plays a protective role by regulating ferroptosis is unknown. Objective: We aimed to investigate the inhibitory effects of EA on ferroptosis in MCAO rats. Methods: We used 36 adult male Sprague-Dawley rats in this study. MCAO rats were established according to the Zea method and treated with EA at a continuous wave of 2/100 Hz and ~2-4 V for 30 min for 7 consecutive days. We analyzed the coordinated motor deficit and volume of cerebral infarction in vivo through 9.4-tesla magnetic resonance imaging. Then, the ischemic brain tissue was isolated and the levels of malondialdehyde (MDA), superoxide dismutase (SOD), glutathione (GSH), and iron were determined. Western blotting and real-time quantitative PCR were performed to evaluate the expression of glutathione peroxidase 4 (GPX4), transferrin (Tf), transferrin receptor 1 (TfR1), and ferritin heavy chain 1 (FTH1). To confirm the results, we used a transmission electron microscope to observe the mitochondrial morphology. Results: EA intervention significantly decreased the oxidative stress level and inhibited ferroptosis. EA significantly improved coordinated motor deficit (P < 0.01) and decreased cerebral infarct volume (P < 0.01) in the EA + MCAO group, compared with the MCAO group. EA downregulated the level of MDA (P < 0.01) and total iron (P < 0.01) and upregulated the level of SOD (P < 0.01) and GSH (P < 0.01) in the EA + MCAO group, compared with the MCAO group. EA increased the levels of GPX4 and GPX4 mRNA (P < 0.01) and FTH1 and FTH1 mRNA (P < 0.05, P < 0.01), whereas it decreased the levels of Tf and Tf mRNA (P < 0.05, P < 0.01) and TfR1 and TfR1 mRNA (P < 0.01) in the EA + MCAO group, compared with the MCAO group. EA also promoted the recovery of mitochondrial morphology according to the mitochondrial classification system for the ischemic cerebral tissue. Conclusion: Our results indicate that EA can inhibit ferroptosis by regulating oxidative stress and iron-related proteins, thus conferring protection against MCAO in a rat model.

The Therapeutic Effect of Electroacupuncture Therapy for Ischemic Stroke

Electroacupuncture (EA) stimulation is a supplementary therapy and commonly applied in treatment of ischemic stroke in clinic. Stroke is an important cause of long-term disability in individuals in both developing and developed countries. In our review, we show the application of EA stimulation for apoplectic pain, limbs spasticity, blood flow interruption, depression, swallowing dysfunction, aphasia, urinary incontinence, cognition and memory impairment, and constipation following stroke in patients and the related mechanisms in animals. The effectiveness of EA involves with acupoints, intensity, intervals, and duration of intervention for treatment of stroke. The combination of EA and common rehabilitation treatment may exert better effect compared with EA alone. In summary, EA might provide a potential treatment strategy for treating apoplectic patients in clinic.