Pramipexole prevents ischemic cell death via mitochondrial pathways in ischemic stroke

Dopamine receptor agonist pramipexole exerts neuroprotection on global cerebral ischemia/reperfusion injury by inhibiting ferroptosis

OBJECTIVE

To explore the mechanism of dopamine receptor agonist pramipexole in exerting neuroprotection on global cerebral ischemia/reperfusion injury (GCI/R).

MATERIAL AND METHOD

Male Sprague-Dawley rats were randomly divided into four groups (n = 36 in each group), and the Pulsinelli's four-vessel occlusion method was used to establish the rat model of GCI/R injury. Pramipexole administration group was intraperitoneally injected with pramipexole 0.5 mg kg-1 once a day for 14 days. Pramipexole combined with levodopa administration group was intraperitoneally injected with pramipexole 0.5 mg kg-1 and levodopa 50 mg kg-1 once a day for 14 days. The mNSS scores and Y maze test were used to evaluate neurological behaviors. Nissl staining and transmission electron microscopy were used to respectively observe hippocampal neurons and mitochondrial ultrastructure. Molecular biological tests including tissue iron concentration, GSH, MDA were used to detect the degree of ferroptosis. Western blotting was used to detect the expression levels of Nrf2, GPX4, X-CT and p53 proteins at 3 days, 7 days and 14 days after GCI/R injury.

RESULTS

Pramipexole alone or combined with levodopa for 14 days improved neurological behaviors, improved the morphology of neurons, increased the number of surviving neurons in the hippocampal CA1 region of GCI/R rats, which showed similar neuroprotective effects. Pramipexole alone or combined with levodopa for 14 days restored mitochondrial ultrastructure, decreased tissue iron concentration and MDA concentration, increased GSH concentration in the brain of GCI/R rats, which also induced the relative expressions of Nrf2, GPX4 and X-CT proteins and reduced p53 protein.

CONCLUSION

Pramipexole alone or combined with levodopa exert neuroprotection by inhibiting ferroptosis after GCI/R injury via Nrf2/GPX4/SLC7A11 pathway, and long-term intervention could be applied as an effective therapeutic strategy for neuroprotection against GCI/R injury.

Three paradoxes related to the mode of action of pramipexole: The path from D2/D3 dopamine receptor stimulation to modification of dopamine-modulated functions

Pramipexole, a D2/D3 dopamine receptor agonist, is used to treat the motor symptoms of Parkinson's disease, caused by degeneration of the dopaminergic nigrostriatal pathway. There are three paradoxes associated with its mode of action. Firstly, stimulation of D2/D3 receptors leads to neuronal inhibition, although pramipexole does not inhibit but promotes some dopamine-modulated functions, such as locomotion and reinforcement. Secondly, another dopamine-modulated function, arousal, is not promoted but inhibited by pramipexole, leading to sedation. Thirdly, pramipexole-evoked sedation is associated with an increase in pupil diameter, although sedation is expected to cause pupil constriction. To resolve these paradoxes, the path from stimulation of D2/D3 receptors to the modification of dopamine-modulated functions has been tracked. The functions considered are modulated by midbrain dopaminergic nuclei: locomotion - substantia nigra pars compacta (SNc), reinforcement/motivation - ventral tegmental area (VTA), sympathetic activity (as reflected in pupil function) - VTA; arousal - ventral periaqueductal grey (vPAG), with contributions from VTA and SNc. The application of genetics-based molecular techniques (optogenetics and chemogenetics) has enabled tracing the chains of neurones from the dopaminergic nuclei to their final targets executing the functions. The functional neuronal circuits linked to the D2/D3 receptors in the dorsal and ventral striata, stimulated by inputs from SNc and VTA, respectively, may explain how neuronal inhibition induced by pramipexole is translated into the promotion of locomotion, reinforcement/motivation and sympathetic activity. As the vPAG may increase arousal mainly by stimulating cortical D1 dopamine receptors, pramipexole would stimulate only presynaptic D2/D3 receptors on vPAG neurones, curtailing their activity and leading to sedation.

NL-1 Promotes PINK1-Parkin-Mediated Mitophagy Through MitoNEET Inhibition in Subarachnoid Hemorrhage

NL-1 is a mitoNEET ligand known for its antileukemic effects and has recently shown neuroprotective effects in an ischemic stroke model. However, its underlying process in subarachnoid hemorrhage (SAH) is still unclear. Thus, we aimed to investigate the possible mechanism of NL-1 after SAH in rats. 112 male adult Sprague-Dawley rats were used for experiments. SAH model was performed with endovascular perforation. Rats were dosed intraperitoneally (i.p.) with NL-1 (3 mg/kg, 10 mg/kg, 30 mg/kg) or a vehicle (10% DMSO aqueous solution) at 1 h after SAH. A novel mitophagy inhibitor liensinine (60 mg/kg) was injected i.p. 24 h before SAH. SAH grades, short-term and long-term neurological scores were measured for neurobehavior. TdTmediated dUTP nick end labeling (TUNEL) staining, dihydroethidium (DHE) staining and western blot measurements were used to detect the outcomes and mechanisms of NL-1 administration. NL-1 treatment significantly improved short-term neurological behavior in Modified Garcia and beam balance sores in comparison with SAH + vehicle group. NL-1 administration also increased mitoNEET which induced phosphatase and tensin-induced kinase 1 (PINK1), Parkin and LC3II related mitophagy compared with SAH + vehicle group. In addition, the expressions of apoptotic protein Cleaved Caspase-3 and oxidative stress related protein Romo1 in NL-1 treatment group were reversed from SAH + vehicle group. Meanwhile, NL-1 treatment notably reduced TUNEL-positive cells, DHE-positive cells compared with SAH + vehicle group. NL-1 treatment notably improved long-term neurological behavior in rotarod and water maze tests compared to SAH + vehicle group. However, the administration of liensinine may inhibit the treatment effect of NL-1, leading to reduced expression of mitophagy markers Pink1, Parkin, LC3I/II, and increased expressions of Romo1 and Cleaved Caspase-3. NL-1 induced PINK1/PARKIN related mitophagy via mitoNEET, which reduced oxidative stress and apoptosis in early brain injury after SAH in rats. NL-1 may serve as a prospective drug for the treatment of SAH.

Comprehensive analysis of lncRNA-miRNA-mRNA ceRNA network in ischemic stroke

Objective

Competitive endogenous RNA (ceRNA) networks have uncovered a novel mode of RNA interaction, and are implicated in various biological processes and the pathogenesis of IS. This study aimed to explore the potential mechanisms underlying the ceRNA network in IS.

Methods

Four public datasets containing lncRNA and mRNA (GSE22255 and GSE16561) and miRNA (GSE55937 and GSE43618) expression profiles from the GEO database were systematically analyzed to explore the role of RNAs in ischemic stroke (IS). Differentially expressed mRNAs (DEmRNAs), lncRNAs (DElncRNAs), and miRNAs (DEmiRNAs) between IS and normal control samples were identified. LncRNA-miRNA and miRNA-mRNA interactions were predicted, and the competing endogenous RNA (ceRNA) regulatory network was constructed using the Cytoscape software. The correlation between the RNAs in the ceRNA network and the clinical features of the samples was evaluated. Finally, principal component analysis was performed on the RNAs that constitute the ceRNA regulatory network, and their differential expression and principal component relationships among different types of samples were observed.

Results

A total of 224 DEmRNAs, 7 DEmiRNAs, and four DElncRNAs related to IS in four datasets were identified. Then, through target gene prediction, a lncRNA-miRNA-mRNA ceRNA network that contained 3 DElncRNAs, 2 DEmiRNAs, and 24 DEmRNAs was constructed. Correlations of the clinical characteristics showed that PART1 and SERPINH1 were related to clinical diseases, WNK1 was related to lifestyle, and seven RNAs were related to age. PCA results indicate that three principal components of PC1, PC2, and PC3 can clearly distinguish between control and IS samples.

Conclusion

Overall, we constructed a ceRNA network in IS, which could offer insights into the molecular mechanism and potential prognostic biomarkers for further research.

Platinum-Loaded Cerium Oxide Capable of Repairing Neuronal Homeostasis for Cerebral Ischemia-Reperfusion Injury Therapy

Effective neuroprotective agents are required to prevent neurological damage caused by reactive oxygen species (ROS) generated by cerebral ischemia-reperfusion injury (CIRI) following an acute ischemic stroke. Herein, it is aimed to develop the neuroprotective agents of cerium oxide loaded with platinum clusters engineered modifications (Ptn-CeO2). The density functional theory calculations show that Ptn-CeO2 could effectively scavenge ROS, including hydroxyl radicals (·OH) and superoxide anions (·O2 -). In addition, Ptn-CeO2 exhibits the superoxide dismutase- and catalase-like enzyme activities, which is capable of scavenging hydrogen peroxide (H2O2). The in vitro studies show that Ptn-CeO2 could adjust the restoration of the mitochondrial metabolism to ROS homeostasis, rebalance cytokines, and feature high biocompatibility. The studies in mice CIRI demonstrate that Ptn-CeO2 could also restore cytokine levels, reduce cysteine aspartate-specific protease (cleaved Caspase 3) levels, and induce the polarization of microglia to M2-type macrophages, thus inhibiting the inflammatory responses. As a result, Ptn-CeO2 inhibits the reperfusion-induced neuronal apoptosis, relieves the infarct volume, reduces the neurological severity score, and improves cognitive function. Overall, these findings suggest that the prominent neuroprotective effect of the engineered Ptn-CeO2 has a significant neuroprotective effect and provides a potential therapeutic alternative for CIRI.

A Thrombin-Activated Peptide-Templated Nanozyme for Remedying Ischemic Stroke via Thrombolytic and Neuroprotective Actions

Ischemic stroke (IS) is one of the most common causes of disability and death. Thrombolysis and neuroprotection are two current major therapeutic strategies to overcome ischemic and reperfusion damage. In this work, a novel peptide-templated manganese dioxide nanozyme (PNzyme/MnO2 ) is designed that integrates the thrombolytic activity of functional peptides with the reactive oxygen species scavenging ability of nanozymes. Through self-assembled polypeptides that contain multiple functional motifs, the novel peptide-templated nanozyme is able to bind fibrin in the thrombus, cross the blood-brain barrier, and finally accumulate in the ischemic neuronal tissues, where the thrombolytic motif is "switched-on" by the action of thrombin. In mice and rat IS models, the PNzyme/MnO2 prolongs the blood-circulation time and exhibits strong thrombolytic action, and reduces the ischemic damages in brain tissues. Moreover, this peptide-templated nanozyme also effectively inhibits the activation of astrocytes and the secretion of proinflammatory cytokines. These data indicate that the rationally designed PNzyme/MnO2 nanozyme exerts both thrombolytic and neuroprotective actions. Giving its long half-life in the blood and ability to target brain thrombi, the biocompatible nanozyme may serve as a novel therapeutic agent to improve the efficacy and prevent secondary thrombosis during the treatment of IS.

Recombinant human brain natriuretic peptide attenuates ischemic brain injury in mice by inhibiting oxidative stress and cell apoptosis via activation of PI3K/AKT/Nrf2/HO-1 pathway

Ischemic stroke followed by cerebral artery occlusion is a main cause of chronic disability worldwide. Recombinant human brain natriuretic peptide (rhBNP) has been reported to alleviate sepsis-induced cognitive dysfunction and brain I/R injury. However, the function and molecular mechanisms of rhBNP in ischemic brain injury have not been clarified. For establishment of an animal model of ischemic brain injury, C57BL/6 mice were treated with middle cerebral artery occlusion (MCAO) surgery for 1 h and reperfusion for 24 h. After subcutaneous injection of rhBNP into model mice, neurologic deficits were assessed by evaluating behavior of mice according to Longa scoring system, and TTC staining was utilized to determine the brain infarct size of mice. The levels of oxidative stress markers, superoxide dismutase (SOD), catalase (CAT), glutathione (GSH) and malondialdehyde (MDA), were detected in hippocampal tissues of mice by corresponding kits. Cell apoptosis in hippocampus tissues was examined by TUNEL staining. Protein levels of antioxidant enzymes (HO-1 and NQO1) in cerebral cortex, apoptotic markers (Bax, Bcl-2, and cleaved caspase), and PI3K/AKT pathway-associated factors in hippocampus were tested by western blot analysis. The results revealed that injection of rhBNP decreased neurologic deficit scores, the percent of brain water content, and infarct volume. Additionally, rhBNP downregulated MDA level, upregulated the levels of SOD, CAT, and GSH in hippocampus of mice, and increased protein levels of HO-1 and NQO1 in the cortex. Cell apoptosis in hippocampus tissues of model mice was inhibited by rhBNP which was shown as the reduced TUNEL-positive cells, the decreased Bax, cleaved caspase-3, and cleaved caspase-9 protein levels, and the enhanced Bcl-2 protein level. In addition, rhBNP treatment activated the PI3K/AKT signaling pathway and upregulated the protein levels of HO-1 and NRF2. Overall, rhBNP activates the PI3K/AKT/HO-1/NRF2 pathway to attenuate ischemic brain injury in mice after MCAO by suppression of cell apoptosis and oxidative stress.

Rutaecarpine Mitigates Cognitive Impairment by Balancing Mitochondrial Function Through Activation of the AMPK/PGC1α Pathway

Mitochondrial dysfunction plays a fundamental role in the pathogenesis of cognitive deficit. Rutaecarpine (Rut) is a natural alkaloid with anti-inflammatory and antioxidant properties. This study explored whether Rut treatment could enhance cognitive function by improving mitochondrial function and examined the potential mechanisms underlying this ameliorative effect. We used the Morris water maze and Y-maze tests to evaluate the behavioral effects of Rut in a mouse model of cognitive impairment induced by subcutaneous injection of D-galactose (D-gal). Furthermore, we assessed the effects of Rut on mitochondrial function using cell viability assays, flow cytometry, western blotting, biochemical analysis, and immunochemical techniques in vivo and in vitro. The results indicated Rut treatment attenuated cognitive deficits and mitochondrial dysfunction in the mouse model. Similarly, it maintained the balance of mitochondrial dynamics in neurocytes and reduced oxidative stress and mitochondrial apoptosis in the HT22 cell model. Moreover, we found that these protective effects were dependent on the activation of the AMP-activated protein kinase/proliferator-activated receptor gamma coactivator 1-alpha (AMPK/PGC1α) signaling pathway. Our data indicate that Rut treatment are sensitive to reversal cognitive deficits and mitochondrial dysfunction induced by D-gal; this suggests that Rut is a promising mitochondria-targeted therapeutic agent for treating cognitive impairment.

A new perspective on hippocampal synaptic plasticity and post-stroke depression

Post-stroke depression, a common complication after stroke, severely affects the recovery and quality of life of patients with stroke. Owing to its complex mechanisms, post-stroke depression treatment remains highly challenging. Hippocampal synaptic plasticity is one of the key factors leading to post-stroke depression; however, the precise molecular mechanisms remain unclear. Numerous studies have found that neurotrophic factors, protein kinases and neurotransmitters influence depressive behaviour by modulating hippocampal synaptic plasticity. This review further elaborates on the role of hippocampal synaptic plasticity in post-stroke depression by summarizing recent research and analysing possible molecular mechanisms. Evidence for the correlation between hippocampal mechanisms and post-stroke depression helps to better understand the pathological process of post-stroke depression and improve its treatment.

Melatonin Mitigates Rotenone-Induced Oxidative Stress and Mitochondrial Dysfunction in the Drosophila melanogaster Model of Parkinson's Disease-like Symptoms

Parkinson's disease (PD) is the second most common neurodegenerative disorder; however, its etiology remains elusive. Antioxidants are considered to be a promising approach for decelerating neurodegenerative disease progression owing to extensive examination of the relationship between oxidative stress and neurodegenerative diseases. In this study, we investigated the therapeutic effect of melatonin against rotenone-induced toxicity in the Drosophila model of PD. The 3-5 day old flies were divided into four groups: control, melatonin alone, melatonin and rotenone, and rotenone alone groups. According to their respective groups, flies were exposed to a diet containing rotenone and melatonin for 7 days. We found that melatonin significantly reduced the mortality and climbing ability of Drosophila because of its antioxidative potency. It alleviated the expression of Bcl 2, tyrosine hydroxylase (TH), NADH dehydrogenase, mitochondrial membrane potential, and mitochondrial bioenergetics and decreased caspase 3 expression in the Drosophila model of rotenone-induced PD-like symptoms. These results indicate the neuromodulatory effect of melatonin, and that it is likely modulated against rotenone-induced neurotoxicity by suppressing oxidative stress and mitochondrial dysfunctions.

Rapamycin ameliorates brain damage and maintains mitochondrial dynamic balance in diabetic rats subjected to middle cerebral artery occlusion

To investigate the effect of rapamycin on mitochondrial dynamic balance in diabetic rats subjected to cerebral ischemia-reperfusion injury. Male Sprague Dawley (SD) rats (n = 78) were treated with high fat diet combined with streptozotocin injection to construct diabetic model in rats. Transient middle cerebral artery occlusion (MCAO) of 2 hours was induced and the brains were harvested after 1 and 3 days of reperfusion. Rapamycin was injected intraperitoneally for 3 days prior to and immediately after operation, once a day. The neurological function was assessed, infarct volumes were measured and HE staining as well as immunohistochemistry were performed. The protein of hippocampus was extracted and Western blotting were performed to detect the levels of mTOR, mitochondrial dynamin related proteins (DRP1, p-DRP1, OPA1), SIRT3, and Nix/BNIP3L. Diabetic hyperglycemia worsened the neurological function performance (p < 0.01), enlarged infarct size (p < 0.01) and increased ischemic neuronal cell death (p < 0.01). The increased damage was associated with elevations of p-mTOR, p-S6, and p-DRP1; and suppressions of SIRT3 and Nix/BNIP3L. Rapamycin ameliorated diabetes-enhanced ischemic brain damage and reversed the biomarker alterations caused by diabetes. High glucose activated mTOR pathway and caused mitochondrial dynamics toward fission. The protective effect of rapamycin against diabetes-enhanced ischemic brain damage was associated with inhibiting mTOR pathway, redressing mitochondrial dynamic imbalance, and elevating SIRT3 and Nix/BNIP3L expression.

Research progress on the role of hormones in ischemic stroke

Ischemic stroke is a major cause of death and disability around the world. However, ischemic stroke treatment is currently limited, with a narrow therapeutic window and unsatisfactory post-treatment outcomes. Therefore, it is critical to investigate the pathophysiological mechanisms following ischemic stroke brain injury. Changes in the immunometabolism and endocrine system after ischemic stroke are important in understanding the pathophysiological mechanisms of cerebral ischemic injury. Hormones are biologically active substances produced by endocrine glands or endocrine cells that play an important role in the organism's growth, development, metabolism, reproduction, and aging. Hormone research in ischemic stroke has made very promising progress. Hormone levels fluctuate during an ischemic stroke. Hormones regulate neuronal plasticity, promote neurotrophic factor formation, reduce cell death, apoptosis, inflammation, excitotoxicity, oxidative and nitrative stress, and brain edema in ischemic stroke. In recent years, many studies have been done on the role of thyroid hormone, growth hormone, testosterone, prolactin, oxytocin, glucocorticoid, parathyroid hormone, and dopamine in ischemic stroke, but comprehensive reviews are scarce. This review focuses on the role of hormones in the pathophysiology of ischemic stroke and discusses the mechanisms involved, intending to provide a reference value for ischemic stroke treatment and prevention.

Nano-integrated cascade antioxidases opsonized by albumin bypass the blood-brain barrier for treatment of ischemia-reperfusion injury

Potent antioxidative drugs are urgently needed to treat ischemia-reperfusion (I/R) induced reactive oxygen species (ROS)-mediated cerebrovascular and neural injury during ischemia strokes. However, current antioxidative agents have limited application in such disease due to low blood-brain barrier (BBB) penetration. We herein designed a "neutrophil piggybacking" strategy based on albumin opsonized nanoparticles co-encapsulated with antioxidases catalase (CAT) and superoxide dismutase 1 (SOD1). The system utilized the natural potential of neutrophils to target inflamed tissues to deliver antioxidases to injured sites in the brain. In addition, the system was integrated with a selenium (Se)-containing crosslinker to inhibit ferroptosis. We showed that the nanoparticles opsonized in the hybrid form rather than with an albumin-shell structure exhibited enhanced neutrophil targeting and efficient BBB penetration in vitro and in vivo. We further showed that the neutrophil-mediated delivery of antioxidases effectively reduced oxidative damage and apoptosis of neurons in brain tissue in a transient middle cerebral artery occlusion (tMCAO) mouse model. Moreover, the successful delivery of Se with the nanoparticles increased the expression of glutathione peroxidase 4 (GPX4) and effectively inhibited neuronal ferroptosis, achieving a satisfactory neuroprotective effect in I/R injury mice. Our study demonstrated that the rationally designed nanomedicines using the "neutrophil piggybacking" strategy can efficiently penetrate the BBB, greatly expanding the application of nanomedicines in the treatment of central nervous system (CNS) diseases.

Ras-related protein Rab-20 inhibition alleviates cerebral ischemia/reperfusion injury by inhibiting mitochondrial fission and dysfunction

Ras-related protein Rab-20 (Rab20) is induced in hypoxia and contributes to hypoxia-induced apoptosis. However, the role and mechanism of Rab20 in cerebral ischemia/reperfusion (I/R) injury need to be elucidated. We established a cerebral I/R injury model in the mice and an oxygen-glucose deprivation/reoxygenation (OGD/R) model in HT22 cells to determine the effects of Rab20 in cerebral I/R injury. Rab20 expression was upregulated in mice after I/R and in HT22 cells after OGD/R. Upregulated Rab20 was mainly located in neurons. Rab20 inhibition significantly alleviated brain infarct volume, neurological deficits, and neuronal apoptosis in mice after I/R. Moreover, Rab20 knockdown significantly ameliorated the OGD/R-induced inhibition of cell viability and apoptotic cell death in HT22 cells. Rab20 knockdown significantly alleviated OGD/R-induced mitochondrial fission by repressing mitochondrial dynamin-related protein 1 (Drp-1) recruitment and increasing Drp-1 (Ser637) phosphorylation and ameliorated mitochondrial dysfunction by reducing the mitochondrial reactive oxygen species (ROS) and cellular calcium accumulation and increasing the mitochondrial membrane potential. In addition, Rab20 knockdown significantly alleviated cytochrome c release from the mitochondria into the cytosol in HT22 cells after OGD/R. Rab20 contributes to cerebral I/R injury by regulating mitochondria-associated apoptosis pathways. Targeting Rab20 may be an attractive strategy for the treatment of cerebral I/R injury.

Venous stroke–a stroke subtype that should not be ignored

Based on the etiology, stroke can be classified into ischemic or hemorrhagic subtypes, which ranks second among the leading causes of death. Stroke is caused not only by arterial thrombosis but also by cerebral venous thrombosis. Arterial stroke is currently the main subtype of stroke, and research on this type has gradually improved. Venous thrombosis, the particular type, accounts for 0.5–1% of all strokes. Due to the lack of a full understanding of venous thrombosis, as well as its diverse clinical manifestations and neuroimaging features, there are often delays in admission for it, and it is easy to misdiagnose. The purpose of this study was to review the pathophysiology mechanisms and clinical features of arterial and venous thrombosis and to provide guidance for further research on the pathophysiological mechanism, clinical diagnosis, and treatment of venous thrombosis. This review summarizes the pathophysiological mechanisms, etiology, epidemiology, symptomatology, diagnosis, and treatment heterogeneity of venous thrombosis and compares it with arterial stroke. The aim is to provide a reference for a comprehensive understanding of venous thrombosis and a scientific understanding of various pathophysiological mechanisms and clinical features related to venous thrombosis, which will contribute to understanding the pathogenesis of intravenous stroke and provide insight into diagnosis, treatment, and prevention.

Effects of pramipexole on beta-amyloid1-42 memory deficits and evaluation of oxidative stress and mitochondrial function markers in the hippocampus of Wistar rat

Oxidative damage and mitochondrial dysfunction are two prominent pathological features and gradually understood as important pathogenic events for neurodegenerative diseases, including aging and Alzheimer's disease (AD). The present study was aimed to explore the prolonged treatment of pramipexole (PPX) following amyloid beta (Aβ_1-42)-induced cognitive deficits, oxidative stress, and mitochondrial dysfunction in Wistar rat model. We have found that PPX (1.0mg/kg, b.wt.) can rescue cognitive impairments of Aβ_1-42-infused rats in Morris water maze. At the same time, PPX attenuated Aβ_1-42-induced oxidative damage and increased reduced-glutathione content level, decreased lipid peroxidation rate and suppressed the activity of acetylcholinesterase and shows antioxidant effects. Additionally, PPX treatment has shown inhibition of mitochondrial reactive oxygen species production and restored mitochondrial membrane potential, oxidative phosphorylation, and enhanced ATP levels in Aβ_1-42 rats. Furthermore, PPX treatment reduced bioenergetics loss and dynamics alterations by regulating PGC-1α protein level and mitigating translocation of Bax and Drp-1 to mitochondria and cytochrome-c release into the cytoplasm. PPX also increased mitofusin-2 protein expression, a basic element of mitochondrial fusion process. We conclude that remedial role of PPX in mitigating oxidative damage and mitochondrial perturbation that are modulated in Aβ_1-42 rats may have the propensity in AD pathogenesis.

Calenduloside E alleviates cerebral ischemia/reperfusion injury by preserving mitochondrial function

Calenduloside E (CE) isolated from Aralia elata (Miq.) Seem. is a natural triterpenoid saponin that can reportedly ameliorate myocardial ischemia/reperfusion injury. However, its potential roles and mechanism in cerebral ischemia/reperfusion injury are barely understood. In this study, we established an oxygen-glucose deprivation/reoxygenation (OGD/R) model in HT22 cells. We found that CE significantly attenuated the OGD/R-induced inhibition of cell viability and apoptotic cell death in HT22 cells. Moreover, CE treatment significantly ameliorated OGD/R-induced mitochondrial fission by inhibiting mitochondrial dynamin-related protein 1 (Drp1) recruitment and increasing Drp1 phosphorylation at Ser637. CE treatment significantly ameliorated OGD/R-induced mitochondrial dysfunction by increasing the mitochondrial membrane potential and reducing the mitochondrial ROS and cellular calcium accumulation. Moreover, CE treatment significantly inhibited the OGD/R-induced release of mitochondrial Cytochrome C and increase in Bax, Cleaved-caspase3 and Cleaved-caspase9 protein levels, whereas CE treatment significantly reversed the OGD/R-induced decrease in Bcl-2 and full length of caspase3 and caspase9 protein levels. In vivo, we found that CE treatment significantly ameliorated ischemic/hypoxic-induced brain infarct volume, neurological deficits, and neuronal apoptosis in mice after middle cerebral artery occlusion and reperfusion. CE treatment also significantly ameliorated the mitochondrial transmembrane potential, decreased Cytochrome C release, and reversed the increase in Bax, Cleaved-caspase3 and Cleaved-caspase9 protein levels and the decrease in Bcl-2 and full length of caspase3 and caspase9 protein levels induced by cerebral ischemia/reperfusion (I/R). All these results indicated that CE treatment exerted a neuroprotective effect by ameliorating mitochondrial dysfunction during cerebral I/R injury.

Cyclosporine A loaded brain targeting nanoparticle to treat cerebral ischemia/reperfusion injury in mice

BACKGROUND

Ischemic stroke is one of the main causes of death and disability in the world. The treatment for ischemic stroke is to restore blood perfusion as soon as possible. However, when ischemic brain tissue is re-perfused by blood, the mitochondrial permeability transition pore (mPTP) in neuron and microglia is excessively opened, resulting in the apoptosis of neuron and nerve inflammation. This aggravates nerve injury. Cyclosporine A (CsA) inhibits the over-opening of mPTP, subsequently reducing the release of ROS and the apoptosis of cerebral ischemia/reperfusion injured neuron and microglia. However, CsA is insoluble in water and present in high concentrations in lymphatic tissue. Herein, cerebral infarction tissue targeted nanoparticle (CsA@HFn) was developed to treat cerebral ischemia/reperfusion injury.

RESULTS

CsA@HFn efficiently penetrated the blood-brain barrier (BBB) and selectively accumulated in ischemic area, inhibiting the opening of mPTP and ROS production in neuron. This subsequently reduced the apoptosis of neuron and the damage of BBB. Consequently, CsA@HFn significantly reduced the infarct area. Moreover, CsA@HFn inhibited the recruitment of astrocytes and microglia in ischemic region and polarized microglia into M2 type microglia, which subsequently alleviated the nerve inflammation.

CONCLUSIONS

CsA@HFn showed a significant therapeutic effect on cerebral ischemia/reperfusion injury by alleviating the apoptosis of neuron, nerve inflammation and the damage of BBB in ischemic area. CsA@HFn has great potential in the treatment of ischemic stroke.

MicroRNA-27a-3p relieves inflammation and neurologic impairment after cerebral ischemia reperfusion via inhibiting LITAF and the TLR4/NF-κB pathway

Cerebral ischemia reperfusion (CIR) affects microRNA (miR) expression and causes substantial inflammation. Here, we investigated the influence and underlying mechanism of miR-27a-3p in rats with CIR. Firstly, Biliverdin treatment relieved cerebral infarction and decreased the levels of serum interleukin (IL)-1β, IL-6 and TNF-α. Through our previous study, we found key miR-27a-3p and its targeted gene LITAF might involve in the molecular mechanism of CIR. Then, the regulation between miR-27a-3p and LITAF was verified by the temporal miR-27a-3p and LITAF expression profiles and luciferase assay. Moreover, intracerebroventricular injection of the miR-27a-3p mimic significantly decreased the LITAF, TLR4, NF-κB and IL-6 levels at 24h post-surgery, whereas miR-27a-3p inhibitor reversed these effects. Furthermore, miR-27a-3p mimic could relieve cerebral infarct and neurologic deficit after CIR. In addition, injection of miR-27a-3p mimic decreased neuronal damage induced by CIR. Taken together, our results suggest that miR-27a-3p protect against CIR by relieving inflammation, neuronal damage and neurologic deficit via regulating LITAF and the TLR4/NF-κB pathway.

Intrathecal pramipexole and selegiline for sensory and motor block in rats

BACKGROUND

The purpose of the study was to investigate spinal sensory and motor block by antiparkinsonian drugs (pramipexole and selegiline), and the combination of pramipexole and the local anesthetic lidocaine.

METHODS

Using a technique of spinal blockade in rats, the effects of pramipexole, selegiline, and coadministration of pramipexole and lidocaine on spinal blockades of motor and sensory function were investigated.

RESULTS

Under a concentration of 100 mM, pramipexole displayed more potent and had a longer duration of nociceptive, proprioceptive, and motor block than selegiline, whereas pramipexole and selegiline were less potent in comparison to lidocaine. Pramipexole produced spinal nociceptive, proprioceptive, and motor blocks in a dose-related manner. On the ED₅₀ (50% effective dose) basis, the rank-order potency on nociceptive, proprioceptive, and motor block was pramipexole < lidocaine. The spinal block duration of pramipexole was greater than lidocaine at every equipotent dose tested (ED₂₅, ED₅₀, and ED₇₅). Coadministration of lidocaine (ED₅₀ or ED₉₅) with pramipexole (4.5 μmol/kg) improved the effect (efficacy) and duration of the spinal block.

CONCLUSIONS

Pramipexole and selegiline were less potent than lidocaine to block sensory and motor responses. The duration of the spinal anesthetic effect of pramipexole was longer than lidocaine. At a non-effective dose, pramipexole increased the duration of efficacy of lidocaine.

Bioactive Nanoenzyme Reverses Oxidative Damage and Endoplasmic Reticulum Stress in Neurons under Ischemic Stroke

Designing translational antioxidative agents that could scavenge free radicals produced during reperfusion in brain ischemia stroke and alleviate neurologic damage is the main objective for ischemic stroke treatment. Herein, we explored and simply synthesized a biomimic and translational Mn₃O₄ nanoenzyme (HSA-Mn₃O₄) to constrain ischemic stroke reperfusion-induced nervous system injury. This nanosystem exhibits reduced levels of inflammation and prolonged circulation time and potent ROS scavenging activities. As expected, HSA-Mn₃O₄ effectively inhibits oxygen and glucose deprivation-mediated cell apoptosis and endoplasmic reticulum stress and demonstrates neuroprotective capacity against ischemic stroke and reperfusion injury of brain tissue. Furthermore, HSA-Mn₃O₄ effectively releases Mn ions and promotes the increase of superoxide dismutase 2 activity. Therefore, HSA-Mn₃O₄ inhibits brain tissue damage by restraining cell apoptosis and endoplasmic reticulum stress in vivo. Taken together, this study not only sheds light on design of biomimic and translational nanomedicine but also reveals the neuroprotective action mechanisms against ischemic stroke and reperfusion injury.

Functional Recovery Caused by Human Adipose Tissue Mesenchymal Stem Cell-Derived Extracellular Vesicles Administered 24 h after Stroke in Rats

Ischemic stroke is a major cause of death and disability, intensely demanding innovative and accessible therapeutic strategies. Approaches presenting a prolonged period for therapeutic intervention and new treatment administration routes are promising tools for stroke treatment. Here, we evaluated the potential neuroprotective properties of nasally administered human adipose tissue mesenchymal stem cell (hAT-MSC)-derived extracellular vesicles (EVs) obtained from healthy individuals who underwent liposuction. After a single intranasal EV (200 µg/kg) administered 24 h after a focal permanent ischemic stroke in rats, a higher number of EVs, improvement of the blood-brain barrier, and re-stabilization of vascularization were observed in the recoverable peri-infarct zone, as well as a significant decrease in infarct volume. In addition, EV treatment recovered long-term motor (front paws symmetry) and behavioral impairment (short- and long-term memory and anxiety-like behavior) induced by ischemic stroke. In line with these findings, our work highlights hAT-MSC-derived EVs as a promising therapeutic strategy for stroke.

Recent Advances in Molecular Pathways and Therapeutic Implications Targeting Mitochondrial Dysfunction for Alzheimer's Disease

Alzheimer's disease (AD) is a neurodegenerative disorder which leads to mental deterioration due to aberrant accretion of misfolded proteins in the brain. According to mitochondrial cascade hypothesis, mitochondrial dysfunction is majorly involved in the pathogenesis of AD. Many drugs targeting mitochondria to treat and prevent AD are in different phases of clinical trials for the evaluation of safety and efficacy as mitochondria are involved in various cellular and neuronal functions. Mitochondrial dynamics is regulated by fission and fusion processes mediated by dynamin-related protein (Drp1). Inner membrane fusion takes place by OPA1 and outer membrane fusion is facilitated by mitofusin1 and mitofusin2 (Mfn1/2). Excessive calcium release also impairs mitochondrial functions; to overcome this, calcium channel blockers like nilvadipine are used. Another process acting as a regulator of mitochondrial function is mitophagy which is involved in the removal of damaged and non-functional mitochondria however this process is also altered in AD due to mutations in Presenilin1 (PS1) and Amyloid Precursor Protein (APP) gene. Mitochondrial dynamics is altered in AD which led to the discovery of various fission protein (like Drp1) inhibitors and drugs that promote fusion. Modulations in AMPK, SIRT1 and Akt pathways can also come out to be better therapeutic strategies as these pathways regulate functions of mitochondria. Oxidative phosphorylation is major generator of Reactive Oxygen Species (ROS) leading to mitochondrial damage; therefore reduction in production of ROS by using antioxidants like MitoQ, Curcumin and Vitamin Eis quiteeffective.

Nanozymes Regulate Redox Homeostasis in ROS-Related Inflammation

Reactive oxygen species (ROS), in moderate amounts, play an essential role in regulating different physiological functions in organisms. However, increased amounts of ROS may cause oxidative stress and damage to biomolecules, leading to a variety of diseases including inflammation and even cancer. Therefore, ROS scavenging reagents are needed to maintain healthy levels of ROS. With considerable advances in nanotechnology, nanozymes possess SOD or CAT-like activities with outstanding free radical scavenging activity, facile synthesis conditions, and excellent biocompatibility. Based on these extraordinary properties, nanozymes has been used to modulate the redox homeostasis and relieve the ROS-related injury. This has led to the emergence of nanozyme-based therapies. In the current review, we presented recently developed applications of nanozymes to treat ROS-dependent disorders with an emphasis on inflammatory and brain diseases.

The Mitochondrial mitoNEET Ligand NL-1 Is Protective in a Murine Model of Transient Cerebral Ischemic Stroke

PURPOSE

Therapeutic strategies to treat ischemic stroke are limited due to the heterogeneity of cerebral ischemic injury and the mechanisms that contribute to the cell death. Since oxidative stress is one of the primary mechanisms that cause brain injury post-stroke, we hypothesized that therapeutic targets that modulate mitochondrial function could protect against reperfusion-injury after cerebral ischemia, with the focus here on a mitochondrial protein, mitoNEET, that modulates cellular bioenergetics.

METHOD

In this study, we evaluated the pharmacology of the mitoNEET ligand NL-1 in an in vivo therapeutic role for NL-1 in a C57Bl/6 murine model of ischemic stroke.

RESULTS

NL-1 decreased hydrogen peroxide production with an IC50 of 5.95 μM in neuronal cells (N2A). The in vivo activity of NL-1 was evaluated in a murine 1 h transient middle cerebral artery occlusion (t-MCAO) model of ischemic stroke. We found that mice treated with NL-1 (10 mg/kg, i.p.) at time of reperfusion and allowed to recover for 24 h showed a 43% reduction in infarct volume and 68% reduction in edema compared to sham-injured mice. Additionally, we found that when NL-1 was administered 15 min post-t-MCAO, the ischemia volume was reduced by 41%, and stroke-associated edema by 63%.

CONCLUSION

As support of our hypothesis, as expected, NL-1 failed to reduce stroke infarct in a permanent photothrombotic occlusion model of stroke. This report demonstrates the potential therapeutic benefits of using mitoNEET ligands like NL-1 as novel mitoceuticals for treating reperfusion-injury with cerebral stroke.

9-Methylfascaplysin exerts anti-ischemic stroke neuroprotective effects via the inhibition of neuroinflammation and oxidative stress in rats

OBJECTIVES

This study was aimed to investigate the neuroprotective effects of 9-methylfascaplysin, a novel marine derivative derived from sponge, against middle cerebral artery occlusion/reperfusion (MCAO)-induced motor impairments, neuroinflammation and oxidative stress in rats.

METHODS

Neurological and behavioral tests were used to evaluate behavioral changes. The 2, 3, 5-triphenyltetrazolium chloride staining was used to determine infarct size and edema extent. Activated microglia/macrophage was analyzed by immunohistochemical staining of Iba-1. RT-PCR and ELISA were used to measure the expression of inducible nitric oxide synthase, tumor necrosis factor-α, interleukin-1β, CD16 and CD206. Western blotting analysis was performed to explore the activation of nuclear factor-κB (NF-κB) and NLRP3. The levels of oxidative stress were studied by evaluating the activities of superoxide dismutase, catalase and glutathione peroxidase.

RESULTS

Post-occlusion intracerebroventricular injection of 9-methylfascaplysin significantly attenuated motor impairments and infarct size in MCAO rats. Moreover, 9-methylfascaplysin reduced the activation of microglia/macrophage in ischemic penumbra as evidenced by the decreased Iba-1-positive area and the reduced expression of pro-inflammatory factors. Furthermore, 9-methylfascaplysin inhibited MCAO-induced oxidative stress and activation of NF-κB and NLRP3 inflammasome.

CONCLUSION

All the results suggested that 9-methylfascaplysin might produce neuroprotective effects against MCAO via the reduction of oxidative stress and neuroinflammation, simultaneously, possibly via the inhibition of NF-κB and NLRP3 inflammasome.

Nrf2/HO-1 mediates the neuroprotective effects of pramipexole by attenuating oxidative damage and mitochondrial perturbation after traumatic brain injury in rats

Pramipexole (PPX), a D2-like receptor agonist, is generally used in the treatment of Parkinson's disease and restless leg syndrome. Its neuroprotective effects have been shown against various neurological disorders. Recent research work has demonstrated that PPX exerts neuroprotection through mitochondria. However, the neuromodulator-related effects of PPX against traumatic brain injury (TBI) remain unexplored. The present study, therefore, investigated the mechanism of neuroprotection by PPX against oxidative stress, mitochondrial dysfunction and neuronal damage following TBI in rats. We hypothesized that the neuroprotection by PPX in TBI-subjected rats might involve activation of the Nrf2/HO-1 (also known as Nfe2l2/Hmox1) signaling pathway. PPX was injected intraperitoneally (0.25 mg/kg body weight and 1.0 mg/kg body weight) at different time intervals post-TBI. Several neurobehavioral parameters were assessed at 48 h post-TBI, and the brain was isolated for molecular and biochemical analysis. The results demonstrated that PPX treatment significantly improved the behavioral deficits, decreased the lipid peroxidation rate, increased glutathione levels and decreased 4-hydroxynonenal levels in TBI-subjected rats. PPX also increased the activities of glutathione peroxidase and superoxide dismutase enzymes. In addition, PPX treatment inhibited mitochondrial reactive oxygen species production, restored mitochondrial membrane potential and increased ATP levels after a TBI. Further, PPX treatment reduced the Bax/Bcl2 ratio and translocation of Bax to mitochondria and cytochrome-c to the cytosol. Finally, PPX treatment greatly accelerated the translocation of Nrf2 to the nucleus and upregulated HO-1 protein expression. We conclude that the neuroprotective effects of PPX are mediated by activation of the Nrf2/HO-1 signaling pathway following TBI.This article has an associated First Person interview with the first author of the paper.

Sirt1-ROS-TRAF6 Signaling-Induced Pyroptosis Contributes to Early Injury in Ischemic Mice

Stroke is an acute cerebro-vascular disease with high incidence and poor prognosis, most commonly ischemic in nature. In recent years, increasing attention has been paid to inflammatory reactions as symptoms of a stroke. However, the role of inflammation in stroke and its underlying mechanisms require exploration. In this study, we evaluated the inflammatory reactions induced by acute ischemia and found that pyroptosis occurred after acute ischemia both in vivo and in vitro, as determined by interleukin-1β, apoptosis-associated speck-like protein, and caspase-1. The early inflammation resulted in irreversible ischemic injury, indicating that it deserves thorough investigation. Meanwhile, acute ischemia decreased the Sirtuin 1 (Sirt1) protein levels, and increased the TRAF6 (TNF receptor associated factor 6) protein and reactive oxygen species (ROS) levels. In further exploration, both Sirt1 suppression and TRAF6 activation were found to contribute to this pyroptosis. Reduced Sirt1 levels were responsible for the production of ROS and increased TRAF6 protein levels after ischemic exposure. Moreover, N-acetyl-L-cysteine, an ROS scavenger, suppressed the TRAF6 accumulation induced by oxygen-glucose deprivation via suppression of ROS bursts. These phenomena indicate that Sirt1 is upstream of ROS, and ROS bursts result in increased TRAF6 levels. Further, the activation of Sirt1 during the period of ischemia reduced ischemia-induced injury after 72 h of reperfusion in mice with middle cerebral artery occlusion. In sum, these results indicate that pyroptosis-dependent machinery contributes to the neural injury during acute ischemia via the Sirt1-ROS-TRAF6 signaling pathway. We propose that inflammatory reactions occur soon after oxidative stress and are detrimental to neuronal survival; this provides a promising therapeutic target against ischemic injuries such as a stroke.

Neuroprotective effect of cajaninstilbene acid against cerebral ischemia and reperfusion damages by activating AMPK/Nrf2 pathway

Introduction

Ischemic stroke is one of the leading causes of death worldwide. Recently, neuroprotection is regarded as an important preventative and therapeutic strategy for ischemic stroke. Cajaninstilbene acid (CSA), a unique stilbenoid with a styryl group, is a potential neuroprotective agent.

Objectives

Hence, this study aimed to evaluate the neuroprotective effect and molecular mechanism of CSA against cerebral ischemia/reperfusion (I/R) damages.

Methods

Cerebral ischemia was modeled by oxygen and glucose deprivation (OGD) in SH-SY5Y cells or transient intraluminal suture middle cerebral artery occlusion (MCAO) in rats, and tert-butyl hydroperoxide (t-BHP) was used to induce oxidative stress in SH-SY5Y cells. CSA (2.5, 5 mg/kg) was intraperitoneally given upon reperfusion after 2 h of MCAO. The signaling pathways were analyzed by Western blotting and inhibitor blocking.

Results

CSA possessed significant neuroprotective activity, as evidenced by the reduced cell death in OGD/R or t-BHP injured SH-SY5Y cells, and decreased infarct volume and neurological deficits in MCAO/R rats. Further studies indicated that the protective effect was achieved via the antioxidant activity of CSA, which decreased the oxidative stress and its related mitochondrial dysfunction in SH-SY5Y cells. Notably, Nrf2 was activated in SH-SY5Y cells and MCAO/R rats by CSA, and the inhibition of Nrf2 by brusatol weakened CSA-mediated neuroprotection. Furthermore, after applying a series of kinase inhibitors, CSA-induced Nrf2 activation was markedly inhibited by BML-275 (an AMPK inhibitor), implying that AMPK was the dominant kinase to regulate the Nrf2 pathway for CSA’s neuroprotective effects with enhanced AMPK phosphorylation observed both in vivo and in vitro.

Conclusion

CSA exerted neuroprotection via activating the AMPK/Nrf2 pathway to reduce I/R-induced cellular oxidative stress and mitochondrial disfunction. CSA could be a potential neuroprotective drug candidate for the treatment of ischemic stroke.

Stem Cells as Drug-like Biologics for Mitochondrial Repair in Stroke

Stroke is a devastating condition characterized by widespread cell death after disruption of blood flow to the brain. The poor regenerative capacity of neural cells limits substantial recovery and prolongs disruptive sequelae. Current therapeutic options are limited and do not adequately address the underlying mitochondrial dysfunction caused by the stroke. These same mitochondrial impairments that result from acute cerebral ischemia are also present in retinal ischemia. In both cases, sufficient mitochondrial activity is necessary for cell survival, and while astrocytes are able to transfer mitochondria to damaged tissues to rescue them, they do not have the capacity to completely repair damaged tissues. Therefore, it is essential to investigate this mitochondrial transfer pathway as a target of future therapeutic strategies. In this review, we examine the current literature pertinent to mitochondrial repair in stroke, with an emphasis on stem cells as a source of healthy mitochondria. Stem cells are a compelling cell type to study in this context, as their ability to mitigate stroke-induced damage through non-mitochondrial mechanisms is well established. Thus, we will focus on the latest preclinical research relevant to mitochondria-based mechanisms in the treatment of cerebral and retinal ischemia and consider which stem cells are ideally suited for this purpose.

Pramipexole Reduces zif-268 mRNA Expression in Brain Structures involved in the Generation of Harmaline-Induced Tremor

Essential tremor is one of the most common neurological disorders, however, it is not sufficiently controlled with currently available pharmacotherapy. Our recent study has shown that pramipexole, a drug efficient in inhibiting parkinsonian tremor, reduced the harmaline-induced tremor in rats, generally accepted to be a model of essential tremor. The aim of the present study was to investigate brain targets for the tremorolytic effect of pramipexole by determination of the early activity-dependent gene zif-268 mRNA expression. Tremor in rats was induced by harmaline administered at a dose of 15 mg/kg ip. Pramipexole was administered at a low dose of 0.1 mg/kg sc. Tremor was measured by Force Plate Actimeters where four force transducers located below the corners of the plate tracked the animal's position on a Cartesian plane. The zif-268 mRNA expression was analyzed by in situ hybridization in brain slices. Harmaline induced tremor and increased zif-268 mRNA levels in the inferior olive, cerebellar cortex, ventroanterior/ventrolateral thalamic nuclei and motor cortex. Pramipexole reversed both the harmaline-induced tremor and the increase in zif-268 mRNA expression in the inferior olive, cerebellar cortex and motor cortex. Moreover, the tremor intensity correlated positively with zif-268 mRNA expression in the above structures. The present results seem to suggest that the tremorolytic effect of pramipexole is related to the modulation of the harmaline-increased neuronal activity in the tremor network which includes the inferior olive, cerebellar cortex and motor cortex. Potential mechanisms underlying the above pramipexole action are discussed.

Mitochondrial MPTP: A Novel Target of Ethnomedicine for Stroke Treatment by Apoptosis Inhibition

Mammalian mitochondrial permeability transition pore (MPTP), across the inner and outer membranes of mitochondria, is a nonspecific channel for signal transduction or material transfer between mitochondrial matrix and cytoplasm such as maintenance of Ca²⁺ homeostasis, regulation of oxidative stress signals, and protein translocation evoked by some of stimuli. Continuous MPTP opening has been proved to stimulate neuronal apoptosis in ischemic stroke. Meanwhile, inhibition of MPTP overopening-induced apoptosis has shown excellent efficacy in the treatment of ischemic stroke. Among of which, the potential molecular mechanisms of drug therapy for stroke has also been gradually revealed by researchers. The characteristics of multi-components or multi-targets for ethnic drugs also provide the possibility to treat stroke from the perspective of mitochondrial MPTP. The advantages mentioned above make it necessary for us to explore and clarify the new perspective of ethnic medicine in treating stroke and to determine the specific molecular mechanisms through advanced technologies as much as possible. In this review, we attempt to uncover the relationship between abnormal MPTP opening and neuronal apoptosis in ischemic stroke. We further summarized currently authorized drugs, ethnic medicine prescriptions, herbs, and identified monomer compounds for inhibition of MPTP overopening-induced ischemic neuron apoptosis. Finally, we strive to provide a new perspective and enlightenment for ethnic medicine in the prevention and treatment of stroke by inhibition of MPTP overopening-induced neuronal apoptosis.

Ischemic stroke and mitochondria: mechanisms and targets

Stroke is one of the main causes of mortality and disability in most countries of the world. The only way of managing patients with ischemic stroke is the use of intravenous tissue plasminogen activator and endovascular thrombectomy. However, very few patients receive these treatments as the therapeutic time window is narrow after an ischemic stroke. The paucity of stroke management approaches can only be addressed by identifying new possible therapeutic targets. Mitochondria have been a rare target in the clinical management of stroke. Previous studies have only investigated the bioenergetics and apoptotic roles of this organelle; however, the mitochondrion is now considered as a key organelle that participates in many cellular and molecular functions. This review discusses the mitochondrial mechanisms in cerebral ischemia such as its role in reactive oxygen species (ROS) generation, apoptosis, and electron transport chain dysfunction. Understanding the mechanisms of mitochondria in neural cell death during ischemic stroke might help to design new therapeutic targets for ischemic stroke as well as other neurological diseases.

Highly bioactive zeolitic imidazolate framework-8-capped nanotherapeutics for efficient reversal of reperfusion-induced injury in ischemic stroke

Rational design of potent antioxidative agent with high biocompatibility is urgently needed to treat ischemic reperfusion-induced ROS-mediated cerebrovascular and neural injury during ischemia strokes. Here, we demonstrate an in situ synthetic strategy of bioactive zeolitic imidazolate framework-8-capped ceria nanoparticles (CeO₂@ZIF-8 NPs) to achieve enhanced catalytic and antioxidative activities and improved stroke therapeutic efficacy. This nanosystem exhibits prolonged blood circulation time, reduced clearance rate, improved BBB penetration ability, and enhanced brain accumulation, where it effectively inhibits the lipid peroxidation in brain tissues in middle cerebral artery occlusion mice and reduces the oxidative damage and apoptosis of neurons in brain tissue. CeO₂@ZIF-8 also suppresses inflammation- and immune response-induced injury by suppressing the activation of astrocytes and secretion of proinflammatory cytokines, thus achieving satisfactory prevention and treatment in neuroprotective therapy. This study also sheds light on the neuroprotective action mechanisms of ZIF-8-capped nanomedicine against reperfusion-induced injury in ischemic stroke.

Transporter-Mediated Delivery of Small Molecule Drugs to the Brain: A Critical Mechanism That Can Advance Therapeutic Development for Ischemic Stroke

Ischemic stroke is the 5th leading cause of death in the United States. Despite significant improvements in reperfusion therapies, stroke patients still suffer from debilitating neurocognitive deficits. This indicates an essential need to develop novel stroke treatment paradigms. Endogenous uptake transporters expressed at the blood-brain barrier (BBB) provide an excellent opportunity to advance stroke therapy via optimization of small molecule neuroprotective drug delivery to the brain. Examples of such uptake transporters include organic anion transporting polypeptides (OATPs in humans; Oatps in rodents) and organic cation transporters (OCTs in humans; Octs in rodents). Of particular note, small molecule drugs that have neuroprotective properties are known substrates for these transporters and include 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors (i.e., statins) for OATPs/Oatps and 1-amino-3,5-dimethyladamantane (i.e., memantine) for OCTs/Octs. Here, we review current knowledge on specific BBB transporters that can be targeted for improvement of ischemic stroke treatment and provide state-of-the-art perspectives on the rationale for considering BBB transport properties during discovery/development of stroke therapeutics.

Ropinirole induces neuroprotection following reperfusion-promoted mitochondrial dysfunction after focal cerebral ischemia in Wistar rats

Stroke is characterized by an initial ischemia followed by a reperfusion that promotes cascade of damage referred to as primary injury. The loss of mitochondrial function after ischemia, which is characterized by oxidative stress and activation of apoptotic factors is considered to play a crucial role in the proliferation of secondary injury and subsequent brain neuronal cell death. Dopamine D2 receptor agonist, Ropinirole, has been found to promote neuroprotection in Parkinson´s disease and restless leg syndrome. The current study was designed to test its efficacy in preclinical model of stroke. Previously it has been demonstrated that Ropinirole mediates its neuroprotection via mitochondrial pathways. Assuming this, we investigated the effect of Ropinirole on mitochondrial dysfunction, we have shown the positive effect of Ropinirole administration on behavioral deficits and mitochondrial health in an ischemic stroke injury model of transient middle cerebral artery occlusion (tMCAO). Male Wistar rats underwent transient middle cerebral artery occlusion and then received the Ropinirole (10 mg and 20 mg/kg b.w.) at 6 h, 12 and 18 h post occlusion. Behavioral assessment for functional deficits included grip strength, motor coordination and gait analysis. Our findings revealed a significant improvement with Ropinirole treatment in tMCAO animals. Staining of isolated brain slices from Ropinirole-treated rats with 2, 3,5-triphenyltetrazolium chloride (TTC) showed a reduction in the infarct area in comparison to the vehicle group, indicating the presence of an increased number of viable mitochondria. Ropinirole treatment was also able to attenuate mitochondrial reactive oxygen species (ROS) production, as well as block the mitochondrial permeability transition pore (mPTP), in the tMCAO injury model. In addition, it was also able to ameliorate the altered mitochondrial membrane potential and respiration ratio in the ischemic animals, thereby suggesting that Ropinirole has a positive effect on mitochondrial bioenergetics. Ropinirole inhibited the translocation of cytochrome c from mitochondria to cytosol reduces the downstream apoptotic processes. In conclusion, these results demonstrate that Ropinirole treatment is beneficial in preserving the mitochondrial functions that are altered in cerebral ischemic injury and thus can help in defining better therapies.