Stomatin-like protein-2 relieve myocardial ischemia/reperfusion injury by adenosine 5′-monophosphate-activated protein kinase signal pathway

Previous studies have shown that stomatin-like protein-2 (SLP-2) could regulate mitochondrial biogenesis and function. The study was designed to explore the contribution of SLP-2 to the myocardial ischemia and reperfusion (I/R) injury. Anesthetized rats were treated with SLP-2 and subjected to ischemia for 30 minutes before 3 hours of reperfusion. An oxygen-glucose deprivation/reoxygenation model of I/R was established in H9C2 cells. In vivo, SLP-2 significantly improved cardiac function recovery of myocardial I/R injury rats by increasing fractional shortening and ejection fraction. SLP-2 pretreatment alleviated infarct area and myocardial apoptosis, which was paralleled by decreasing the level of cleaved caspase-3 and the ratio of Bax/Bcl-2, increasing the content of superoxide dismutase and reducing oxidative stress damage in serum. In addition, SLP-2 increased the level of ATP and stabilized mitochondrial potential (Ψm). The present in vitro study revealed that overexpression with SLP-2 reduced H9C2 cells apoptosis, accompanied by an increased level of ATP, the ratio of mitochondrial DNA/nuclear DNA, activities of complex II and V, and decreased the production of mitochondrial reactive oxygen species. Simultaneously, SLP-2 activated the adenosine 5′-monophosphate-activated protein kinase (AMPK) signaling pathway in myocardial I/R injury rats and H9C2 cells. This study revealed that SLP-2 mediates the cardioprotective effect against I/R injury by regulating AMPK signaling pathway.     

Butylphthalide Suppresses Neuronal Cells Apoptosis and Inhibits JNK–Caspase3 Signaling Pathway After Brain Ischemia /Reperfusion in Rats

Although Butylphthalide (BP) has protective effects that reduce ischemia-induced brain damage and neuronal cell death, little is known about the precise mechanisms occurring during cerebral ischemia/reperfusion (I/R). Therefore, the aim of this study was to investigate the neuroprotective mechanisms of BP against ischemic brain injury induced by cerebral I/R through inhibition of the c-Jun N-terminal kinase (JNK)–Caspase3 signaling pathway. BP in distilled non-genetically modified Soybean oil was administered intragastrically three times a day at a dosage of 15 mg/(kg day) beginning at 20 min after I/R in Sprague–Dawley rats. Immunohistochemical staining and Western blotting were performed to examine the expression of related proteins, and TUNEL-staining was used to detect the percentage of neuronal apoptosis in the hippocampal CA1 region. The results showed that BP could significantly protect neurons against cerebral I/R-induced damage. Furthermore, the expression of p-JNK, p-Bcl2, p–c-Jun, FasL, and cleaved-caspase3 was also decreased in the rats treated with BP. In summary, our results imply that BP could remarkably improve the survival of CA1 pyramidal neurons in I/R-induced brain injury and inhibit the JNK–Caspase3 signaling pathway.     

Oxidative stress and neuronal death/survival signaling in cerebral ischemia

It has been demonstrated by numerous studies that apoptotic cell death pathways are implicated in ischemic cerebral injury in ischemia models in vivo. Experimental ischemia and reperfusion models, such as transient focal/global ischemia in rodents, have been thoroughly studied and the numerous reports suggest the involvement of cell survival/death signaling pathways in the pathogenesis of apoptotic cell death in ischemic lesions. In these models, reoxygenation during reperfusion provides oxygen as a substrate for numerous enzymatic oxidation reactions and for mitochondrial oxidative phosphorylation to produce adenosine triphosphate. Oxygen radicals, the products of these biochemical and physiological reactions, are known to damage cellular lipids, proteins, and nucleic acids and to initiate cell signaling pathways after cerebral ischemia. Genetic manipulation of intrinsic antioxidants and factors in the signaling pathways has provided substantial understanding of the mechanisms involved in cell death/survival signaling pathways and the role of oxygen radicals in ischemic cerebral injury. Future studies of these pathways could provide novel therapeutic strategies in clinical stroke.     

Overexpression of HSPA12B protects against cerebral ischemia/reperfusion injury via a PI3K/Akt-dependent mechanism

Background and purpose: HSPA12B is a newly discovered member of the Hsp70 family proteins. This study investigated the effects of HSPA12B on focal cerebral ischemia/reperfusion (I/R) injury in mice. Methods: Transgenic mice overexpressing human HSPA12B (Tg) and wild-type littermates (WT) were subjected to 60 min of middle cerebral artery occlusion to induce ischemia and followed by reperfusion (I/R). Neurological deficits, infarct volumes and neuronal death were examined at 6 and 24 hrs after reperfusion. Blood–brain-barrier (BBB) integrity and activated cellular signaling were examined at 3 hrs after reperfusion. Results: After cerebral I/R, Tg mice exhibited improvement in neurological deficits and decrease in infarct volumes, when compared with WT I/R mice. BBB integrity was significantly preserved in Tg mice following cerebral I/R. Tg mice also showed significant decreases in cell injury and apoptosis in the ischemic hemispheres. We observed that overexpression of HSPA12B activated PI3K/Akt signaling and suppressed JNK and p38 activation following cerebral I/R. Importantly, pharmacological inhibition of PI3K/Akt signaling abrogated the protection against cerebral I/R injury in Tg mice. Conclusions: The results demonstrate that HSPA12B protects the brains from focal cerebral I/R injury. The protective effect of HSPA12B is mediated though a PI3K/Akt-dependent mechanism. Our results suggest that HSPA12B may have a therapeutic potential against ischemic stroke.     

Attenuation of mitochondrial injury by L-arginine preconditioning of the liver

The present study was aimed to evaluate the efficacy of L-arginine on mitochondrial function in ischemic and reperfusion (I/R) induced hepatic injury. Adult Wistar rat were subjected to 1 h of partial liver ischemia followed by 3 hour reperfusion. Eighteen wistar rats were divided into three groups viz. sham-operated control group (I) (n = 6), ischemia and reperfusion (I/R) group (II) (n = 6), L-arginine treated group (100 mg/kg body weight/daily by oral route for 7 days before induced ischemia reperfusion maneuver) (III) (n = 6). Mitochondrial injury was assessed in terms of decreased (P < 0.05) activities of mitochondrial antioxidant enzymes (GSH, SOD, CAT), respiratory marker enzymes (NADH dehydrogenase, cytochrome c oxidases) and hepatocytes nitric oxide production. Pre-treatment with L-arginine (10 mg/kg/p.o. for 7 days) significantly counteracted the alternations of hepatic enzymes and mitochondrial respiratory and antioxidant enzymes. In addition, electron microscopy and histopathology study showed the restoration of cellular normalcy and accredits the cytoprotective role of L-arginine against I/R induced hepatocellular injury. On the basis of these findings it may be concluded that L-arginine protects mitochondrial function in hepatic ischemic and reperfused liver.     

Ischemia-induced cleavage of OPA1 at S1 site aggravates mitochondrial fragmentation and reperfusion injury in neurons

Neuronal mitochondrial dynamics are disturbed after ischemic stroke. Optic atrophy 1 (OPA1) and its GTPase activity are involved in maintaining mitochondrial cristae and inner membrane fusion. This study aimed to explore the role of OMA1-mediated OPA1 cleavage (S1-OPA1) in neurons exposed to cerebral ischemia and reperfusion. After oxygen-glucose deprivation (OGD) for 60 min, we found that mitochondrial fragmentation occurred successively in the axon and soma of neurons, accompanied by an increase in S1-OPA1. In addition, S1-OPA1 overexpression significantly aggravated mitochondrial damage in neurons exposed to OGD for 60 min and 24 h after OGD/R, characterized by mitochondrial fragmentation, decreased mitochondrial membrane potential, mitochondrial cristae ultrastructural damage, increased superoxide production, decreased ATP production and increased mitochondrial apoptosis, which was inhibited by the lysine 301 to alanine mutation (K301A). Furthermore, we performed neuron-specific overexpression of S1-OPA1 in the cerebral cortex around ischemia of middle cerebral artery occlusion/reperfusion (MCAO/R) mice. The results further demonstrated in vivo that S1-OPA1 exacerbated neuronal mitochondrial ultrastructural destruction and injury induced by cerebral ischemia-reperfusion, while S1-OPA1-K301 overexpression had no effect. In conclusion, ischemia induced neuronal OMA1-mediated cleavage of OPA1 at the S1 site. S1-OPA1 aggravated neuronal mitochondrial fragmentation and damage in a GTPase-dependent manner, and participated in neuronal ischemia-reperfusion injury.Subject terms: Stroke, Cell death in the nervous system     

Autophagy in ALDH2-elicited cardioprotection against ischemic heart disease: Slayer or savior?

The mitochondrial isoform of aldehyde dehydrogenase (ALDH2) plays a key role in the metabolism of acetaldehyde and other toxic aldehydes. A recent seminal finding has indicated a potential role of ALDH2 activation in the cardioprotection against ischemic injury. Data from our group unveiled a myocardial protective effect of ALDH2 against ischemia/reperfusion (I/R) injury possibly through detoxification of toxic aldehydes

and a differential regulation of autophagy mediated by AMPK-mTOR and Akt-mTOR signaling cascades during ischemia and reperfusion, respectively. These findings suggest not only the therapeutic potential of ALDH2 against I/R injury but also a pivotal role of the AMPK-Akt-mTOR signaling in the paradoxical autophagic regulation of cardiomyocyte survival.     

Atorvastatin Attenuates Ischemia/Reperfusion-Induced Hippocampal Neurons Injury Via Akt-nNOS-JNK Signaling Pathway

Ischemia-induced brain damage leads to apoptosis like delayed neuronal death in selectively vulnerable regions, which could further result in irreversible damages. Previous studies have demonstrated that neurons in the CA1 area of hippocampus are particularly sensitive to ischemic damage. Atorvastatin (ATV) has been reported to attenuate cognitive deficits after stroke, but precise mechanism for neuroprotection remains unknown. Therefore, the aims of this study were to investigate the neuroprotective mechanisms of ATV against ischemic brain injury induced by cerebral ischemia reperfusion. In this study, four-vessel occlusion model was established in rats with cerebral ischemia. Rats were divided into five groups: sham group, I/R group, I/R+ATV group, I/R+ATV+LY, and I/R+SP600125 group. Cresyl violet staining was carried out to examine the neuronal death of hippocampal CA1 region. Immunoblotting was used to detect the expression of the related proteins. Results showed that ATV significantly protected hippocampal CA1 pyramidal neurons against cerebral I/R. ATV could increase the phosphorylation of protein kinase B (Akt1) and nNOS, diminished the phosphorylation of JNK3 and c-Jun, and further inhibited the activation of caspase-3. Whereas, all of the aforementioned effects of ATV were reversed by LY294002 (an inhibitor of Akt1). Furthermore, pretreatment with SP600125 (an inhibitor of JNK) diminished the phosphorylation of JNK3 and c-Jun, and further inhibited the activation of caspase-3 after cerebral I/R. Taken together, our results implied that Akt-mediated phosphorylation of nNOS is involved in the neuroprotection of ATV against ischemic brain injury via suppressing JNK3 signaling pathway that provide a new experimental foundation for stroke therapy.     

Selenium Alleviates Cerebral Ischemia/Reperfusion Injury by Regulating Oxidative Stress,Mitochondrial Fusion and Ferroptosis

To clarify the potential role of selenium (Se) on cerebral ischemia/reperfusion (I/R) injury, we utilized mouse middle cerebral artery occlusion (MCAO) followed by reperfusion as an animal model and oxygen–glucose deprivation and reoxygenation (OGD/R) to treat N2a cells as a cell model, respectively. MCAO model was established in mice and then divided into different groups with or without Se treatment. TTC staining was used to observe whether the cerebral I/R modeling was successful, and the apoptosis level was determined by TUNEL staining. The expression of GPx-4 and p22phox was assessed by western blot. In vitro experiments, the OGD/R induced oxidative stress in N2a cells was assessed by levels of GSH/GSSG, malondialdehyde, superoxide dismutase and iron content, respectively. QRT-PCR was used to detect the mRNA levels of Cox-2, Fth1, Mfn1 and mtDNA in N2a cells. JC-1 staining and flow cytometry was performed to detect the mitochondrial membrane potential. Se treatment alleviated cerebral I/R injury and improved the survival rate of mice. Additionally, Se treatment apparently attenuated oxidative stress and inhibited iron accumulation in MCAO model mice and OGD/R model of N2a cells. In terms of its mechanism, Se could up-regulate Mfn1 expression to alleviate oxidative stress and ferroptosis by promoting mitochondrial fusion in vivo and vitro. These findings suggest that Se may have great potential in alleviating cerebral I/R injury.

     

Hydroxysafflor Yellow A Protects Against Cerebral Ischemia–Reperfusion Injury by Anti-apoptotic Effect Through PI3K/Akt/GSK3β Pathway in Rat

Hydroxysafflor yellow A (HSYA) is the major active chemical component of the flower of the safflower plant, Carthamus tinctorius L. Previously, its neuroprotection against cerebral ischemia–reperfusion (I/R) injury was reported by anti-oxidant action and suppression of thrombin generation. Here, we investigate the role of HSYA in cerebral I/R-mediated apoptosis and possible signaling pathways. Male Wistar rats were subjected to transient middle cerebral artery occlusion for 2 h, followed by 24 h reperfusion. HSYA was administered via tail-vein injection just 15 min after occlusion. The number of apoptotic cells was measured by TUNEL assay, apoptosis-related proteins Bcl-2, Bax and the phosphorylation levels of Akt and GSK3β in ischemic penumbra were assayed by western blot. The results showed that administration of HSYA at the doses of 4 and 8 mg/kg significantly inhibited the apoptosis by decreasing the number of apoptotic cells and increasing the Bcl-2/Bax ratio in rats subjected to I/R injury. Simultaneously, HSYA treatment markedly increased the phosphorylations of Akt and GSK3β. Blockade of PI3K activity by wortmannin dramatically abolished its anti-apoptotic effect and lowered both Akt and GSK3β phosphorylation levels. Taken together, these results suggest that HSYA protects against cerebral I/R injury partly by reducing apoptosis via PI3K/Akt/GSK3β signaling pathway.     

Intrinsic Effects of Gold Nanoparticles on Oxygen–Glucose Deprivation/Reperfusion Injury in Rat Cortical Neurons

This study aimed to investigate the potential effects of gold nanoparticles (Au-NPs) on rat cortical neurons exposed to oxygen–glucose deprivation/reperfusion (OGD/R) and to elucidate the corresponding mechanisms. Primary rat cortical neurons were exposed to OGD/R, which is commonly used in vitro to mimic ischemic injury, and then treated with 5- or 20-nm Au-NPs. We then evaluated cell viability, apoptosis, oxidative stress, and mitochondrial respiration in these neurons. We found that 20-nm Au-NPs increased cell viability, alleviated neuronal apoptosis and oxidative stress, and improved mitochondrial respiration after OGD/R injury, while opposite effects were observed for 5-nm Au-NPs. In terms of the underlying mechanisms, we found that Au-NPs could regulate Akt signaling. Taken together, these results show that 20-nm Au-NPs can protect primary cortical neurons against OGD/R injury, possibly by decreasing apoptosis and oxidative stress, while activating Akt signaling and mitochondrial pathways. Our results suggest that Au-NPs may be potential therapeutic agents for ischemic stroke.

     

Donepezil provides neuroprotective effects against brain injury and Alzheimer's pathology under conditions of cardiac ischemia/reperfusion injury

Cardiac ischemia/reperfusion (I/R) injury induces brain pathology. Donepezil, a well-known acetylcholine esterase (AChE) inhibitor, has been proven to exert neuroprotective effects against several neurodegenerative diseases. However, the comprehensive mechanism regarding the therapeutic potential of donepezil on the brain under cardiac I/R injury remains obscure. Here, we hypothesized that treatment with donepezil ameliorates brain pathology following cardiac I/R injury by decreasing blood brain barrier (BBB) breakdown, oxidative stress, neuroinflammation, mitochondrial dysfunction, mitochondrial dynamics imbalance, microglial activation, amyloid-beta (Aβ) accumulation, neuronal apoptosis, and dendritic spine loss. Forty-eight adult male Wistar rats were subjected to surgery for cardiac I/R injury. Then, rats were randomly divided into four groups to receive either (1) saline (vehicle group), donepezil 3 mg/kg via intravenously administered (2) before ischemia (pretreatment group), (3) during ischemia (ischemia group), or (4) at the onset of reperfusion (reperfusion group). At the end of cardiac I/R paradigm, the brains were evaluated for BBB breakdown, brain inflammation, oxidative stress, mitochondrial function, mitochondrial dynamics, microglial morphology, Aβ production, neuronal apoptosis, and dendritic spine density. Administration of donepezil at all time points equally showed an attenuation of brain damage in response to cardiac I/R injury, as indicated by increased expression of BBB junction protein, reduced brain inflammation and oxidative stress, improved mitochondrial function and mitochondrial dynamics, and alleviated Aβ accumulation and microglial activation, resulting in protection of neuronal apoptosis and preservation of dendritic spine number. These findings suggest that donepezil potentially protects brain pathology caused by cardiac I/R injury regardless the timing of treatment.     

Suppression of REDD1 attenuates oxygen glucose deprivation/reoxygenation-evoked ischemic injury in neuron by suppressing mTOR-mediated excessive autophagy

Cerebral ischemia/reperfusion (I/R) typically occurs after mechanical thrombectomy to treat ischemic stroke, generation of reactive oxygen species (ROS) after reperfusion may result in neuronal insult, ultimately leading to disability and death. Regulated in development and DNA damage responses 1 (REDD1) is a conserved stress response protein under various pathogenic conditions. Recent research confirms the controversial role of REDD1 in injury processes. Nevertheless, the role of REDD1 in cerebral I/R remains poorly defined. In the current study, increased expression of REDD1 was observed in neurons exposed to simulated I/R via oxygen glucose deprivation/reoxygenation (OGD/R) treatment. Knockdown of REDD1 enhanced OGD/R-inhibited cell viability, but suppressed lactate dehydrogenase (LDH) release in neurons upon OGD/R. Simultaneously, suppression of REDD1 also antagonized OGD/R-evoked cell apoptosis, Bax expression, and caspase-3 activity. Intriguingly, REDD1 depression abrogated neuronal oxidative stress under OGD/R condition by suppressing ROS, MDA generation, and increasing antioxidant SOD levels. Further mechanism analysis corroborated the excessive activation of autophagy in neurons upon OGD/R with increased expression of autophagy-related LC3 and Beclin-1, but decreased autophagy substrate p62 expression. Notably, REDD1 inhibition reversed OGD/R-triggered excessive neuronal autophagy. More importantly, depression of REDD1 also elevated the expression of p-mTOR. Preconditioning with mTOR inhibitor rapamycin engendered not only a reduction in mTOR activation, but also a reactivation of autophagy in REDD1 knockdown-neurons upon OGD/R. In addition, blocking the mTOR pathway muted the protective roles of REDD1 inhibition against OGD/R-induced neuron injury and oxidative stress. Together these data suggested that REDD1 may regulate I/R-induced oxidative stress injury in neurons by mediating mTOR-autophagy signaling, supporting a promising therapeutic strategy against brain ischemic diseases.     

Keap-NRF2 signaling contributes to the Notch1 protected heart against ischemic reperfusion injury via regulating mitochondrial ROS generation and bioenergetics

Myocardial ischemia/reperfusion (I/R) injury is recognized as the leading cause of death worldwide. However, the molecular mechanisms involved in this process are still not fully understood. We previously reported that the combined action of Notch1 and Keap1-NRF2 signaling pathway can significantly increase the activity of cardiomyocytes, inhibit the apoptosis of cardiomyocytes, reduce the formation of reactive oxygen species, and improve the antioxidant activity in neonate rat myocardial cells. However, the regulatory mechanism of Notch1 signaling pathway on the NRF2 signaling pathway and its actual role on I/R injury are still unclear. Herein, we found that Keap-NRF2 signaling is activated by Notch1 in RBP-Jκ dependent manner, thus protects the heart against I/R injury via inhibiting the mitochondrial ROS generation and improves the mitochondrial bioenergetics in vitro and in vivo. These results suggest that Keap-NRF2 signaling might become a promising therapeutic strategy for treating myocardial I/R injury.     

Mitochondrial Src tyrosine kinase plays a role in the cardioprotective effect of ischemic preconditioning by modulating complex I activity and mitochondrial ROS generation

Abstract

While ischemic preconditioning (IPC) and other cardioprotective interventions have been proposed to protect the heart from ischemia/reperfusion (I/R) injury by inhibiting mitochondrial complex I activity upon reperfusion, the exact mechanism underlying the modulation of complex I activity remains elusive. This study was aimed to test the hypothesis that IPC modulates complex I activity at reperfusion by activating mitochondrial Src tyrosine kinase, and induces cardioprotection against I/R injury. Isolated rat hearts were preconditioned by three cycles of 5-min ischemia and 5-min reperfusion prior to 30-min index ischemia followed by 2 h of reperfusion. Mitochondrial Src phosphorylation (Tyr⁴¹⁶) was dramatically decreased during I/R, implying inactivation of Src tyrosine kinase by I/R. IPC increased mitochondrial Src phosphorylation upon reperfusion and this was inhibited by the selective Src tyrosine kinase inhibitor PP2. IPC's anti-infarct effect was inhibited by the selective Src tyrosine kinase inhibitor PP2. Complex I activity was significantly increased upon reperfusion, an effect that was prevented by IPC in a Src tyrosine kinase-dependent manner. In support, Src and phospho-Src were found in complex I. Furthermore, IPC prevented hypoxia/reoxygenation-induced mitochondrial reactive oxygen species (ROS) generation and cellular injury in rat cardiomyocytes, which was revoked by PP2. Finally, IPC reduced LDH release induced by both hypoxia/reoxygenation and simulated ischemia/reperfusion, an effect that was reversed by PP2 and Src siRNA. These data suggest that mitochondrial Src tyrosine kinase accounts for the inhibitory action of IPC on complex I and mitochondrial ROS generation, and thereby plays a role in the cardioprotective effect of IPC.     

Phosphorylation of JNK Increases in the Cortex of Rat Subjected to Diabetic Cerebral Ischemia

Previous studies have demonstrated that the c-Jun N-terminal kinase (JNK) pathway plays an important role in inducing neuronal apoptosis following cerebral ischemic injury. JNK signaling pathway in activated during cerebral ischemic injury. It participates in ischemia-induced neuronal apoptosis. However, whether JNK signaling is involved in the process of neuronal apoptosis of diabetes-induced cerebral ischemia is largely unknown. This study was undertaken to evaluate the influence of cerebral ischemia–reperfusion injury on phosphorylation of JNK in diabetic rats. Twenty-four adult streptozotocin induced diabetic and 24 adult non-diabetic rats were randomly subjected to 15 min of forebrain ischemia followed by reperfusion for 0, 1, 3, and 6 h. Sixteen sham-operated diabetic and non-diabetic rats were used as controls. Apoptosis was assessed by terminal deoxynucleotidyl transferase-mediated dUTP nick-end labelling (TUNEL). Protein expression of phospho-JNK was examined by immunohistochemistry and Western blot. The numbers of TUNEL-positive cells and phospho-JNK protein expression in the cerebral cortices after 1, 3 and 6 h reperfusion was significantly higher in diabetic rats compared to non-diabetic animals subjected to ischemia and reperfusion (p < 0.05). Western blot analysis showed significantly higher phospho-JNK protein expression in the cerebral cortices of the diabetic rats after 1 and 3 h reperfusion than that was presented in non-diabetic animals subjected to ischemia and reperfusion (p < 0.05). These findings suggest that increased phosphorylation of JNK may be associated with diabetes-enhanced ischemic brain damage.     

Energy restriction induced SIRT6 inhibits microglia activation and promotes angiogenesis in cerebral ischemia via transcriptional inhibition of TXNIP

Energy restriction (ER) protects against cerebral ischemic injury, but the underlying mechanism remains largely unclear. Here, rats were fed ad libitum (AL) or on an alternate-day food deprivation intermittent fasting (IF) diet for 3 months, followed by middle cerebral artery occlusion (MCAO) surgery. The body weight, infarct volume, and neurological deficit score were accessed at the designated time points. ELISA, qRT-PCR, and Western blotting were used to determine cytokine secretion and the expression of SIRT6, TXNIP, and signaling molecules, respectively. Immunofluorescence evaluated microglial activation and angiogenesis in vivo. For in vitro study, oxygen-glucose deprivation/reoxygenation (OGD/R)-treated cell model was generated. MTT and tube formation assays were employed to determine cell viability and tube formation capability. ChIP assay detected chromatin occupancy of SIRT6 and SIRT6-mediated H3 deacetylation. We found that IF or ER mimetics ameliorated cerebral ischemic brain damage and microglial activation, and potentiated angiogenesis in vivo. ER mimetics or SIRT6 overexpression alleviated cerebral ischemia and reperfusion (I/R)-induced injury in vitro. SIRT6 suppressed TXNIP via deacetylation of H3K9ac and H3K56ac in HAPI cells and BMVECs. Downregulation of SIRT6 reversed ER mimetics-mediated protection during cerebral I/R in vitro. Our study demonstrated that ER-mediated upregulation of SIRT6 inhibited microglia activation and potentiated angiogenesis in cerebral ischemia via suppressing TXNIP.Subject terms: Diseases, Cardiovascular diseases     

Rotenone,a mitochondrial electron transport inhibitor,ameliorates ischemia–reperfusion-induced intestinal mucosal damage in rats

Abstract

In ischemia–reperfusion (I/R)-induced tissue injury, oxygen radicals can be generated by several mechanisms. One of the important sources of oxygen radicals is thought to be mitochondrial respiration. The aim of this study was to investigate the antioxidative defense effect of the mitochondrial electron transport inhibitor, rotenone using the I/R-induced rat intestinal mucosal injury model in vivo. Intestinal ischemia was induced for 30 min by applying a small clamp to the superior mesenteric artery in rats. Rotenone at a dose of 100 mg/kg was given to rats orally 2 h before the ischemia. Intraluminal hemoglobin and protein levels, the mucosal content of thiobarbituric acid-reactive substances (TBARS), the mucosal myeloperoxidase activity, and the content of inflammatory cytokines (CINC-1, TNF-α) were all significantly increased from mean basal levels after 60 min of reperfusion. These increases after I/R were inhibited by treatment with rotenone at a dose of 100 mg/kg. Co-administration with succinate (100 mg/kg), a substrate of the mitochondrial electron transport system, cancelled significant reduction of intraluminal hemoglobin and mucosal TBARS treated with rotenone alone. The results of the present study indicate that rotenone inhibited lipid peroxidation and reduced development of the intestinal mucosal inflammation induced by I/R in rats. This investigation suggests that rotenone has potential as a new therapeutic agent for reperfusion injury.     

Glycogen synthase kinase-3 inhibition reduces ischemic cerebral damage, restores impaired mitochondrial biogenesis and prevents ROS production

This study was designed to test the hypothesis that improved mitochondrial biogenesis could help reducing ischemic cerebral injury. We found that levels of proliferator-activated receptor γ coactivator 1α and nuclear respiratory factor-1, mitochondrial DNA content and other markers of mitochondrial biogenesis and function were reduced in primary mouse cortical neurons under oxygen-glucose deprivation (OGD). The glycogen synthase kinase-3 (GSK-3) inhibitor SB216763 activated an efficient mitochondrial biogenesis program in control cortical neurons and counteracted the OGD-mediated mitochondrial biogenesis impairment. This was accompanied by the activation of an antioxidant response that reduced mitochondrial reactive oxygen species generation and ischemic neuronal damage. The in vitro effects of SB216763 were mimicked by two other structurally unrelated GSK-3 inhibitors. The protective effects of SB216763 on OGD-mediated neuronal damage were abolished in the presence of diverse mitochondrial inhibitors. Finally, when systemically administered in vivo, SB216763 reduced the infarct size and recovered the loss of mitochondrial DNA in mice subjected to permanent middle cerebral artery occlusion. We conclude that GSK-3 inhibition by SB216763 might pave the way of novel promising therapies aimed at stimulating the renewal of functional mitochondria and reducing reactive oxygen species-mediated damage in ischemic stroke.