Postischemic Treatment Research Articles

Orally administrated pterostilbene attenuates acute cerebral ischemia–reperfusion injury in a dose- and time-dependent manner in mice

Pterostilbene (3,5-dimethoxy-4-hydroxystilbene) is a component of blueberry. It has been reported that long-term treatment with blueberry has a neuroprotective effect. However, it has not been reported whether pterostilbene is effective in attenuating cerebral ischemia/reperfusion (I/R) injury. In the present study, focal cerebral ischemia was induced by middle cerebral artery occlusion for 90min followed by reperfusion. To observe the dose-dependent effect, pterostilbene (2.5–80mg/kg, ig) was administered for 3days before ischemia. To determine the time-dependent effect, pterostilbene (10mg/kg, ig) was administered as a single dose at 0, 1, or 3h after reperfusion. Twenty-four hours after I/R, pterostilbene dose-dependently improved neurological function, reduced brain infarct volume, and alleviated brain edema. The most effective dose was 10mg/kg; the therapeutic time window was within 1h after I/R and treatment immediately after reperfusion showed the best protective effect. The protective effect is further confirmed by the results that post-ischemic treatment with pterostilbene (10mg/kg) significantly improved motor function, alleviated blood brain barrier disruption, increased neurons survival and reduced cell apoptosis in cortical penumbra after cerebral I/R. We also found that pterostilbene (10mg/kg) significantly reversed the increased content of malondialdehyde and the decreased activity of superoxide dismutase in the ipsilateral hemisphere. Furthermore, pterostilbene decreased the oxidative stress markers 4-hydroxynonenal and 8-hydroxyguanosine positive cells in the cortical penumbra. All these findings indicate that pterostilbene dose- and time-dependently exerts a neuroprotective effect against acute cerebral I/R injury. This neuroprotective effect of pterostilbene may be associated with its inhibition of oxidative stress and subsequent neuronal apoptosis in the cortical penumbra.

Improving reconstituted HDL composition for efficient post-ischemic reduction of ischemia reperfusion injury.

BackgroundNew evidence shows that high density lipoproteins (HDL) have protective effects beyond their role in reverse cholesterol transport. Reconstituted HDL (rHDL) offer an attractive means of clinically exploiting these novel effects including cardioprotection against ischemia reperfusion injury (IRI). However, basic rHDL composition is limited to apolipoprotein AI (apoAI) and phospholipids; addition of bioactive compound may enhance its beneficial effects.ObjectiveThe aim of this study was to investigate the role of rHDL in post-ischemic model, and to analyze the potential impact of sphingosine-1-phosphate (S1P) in rHDL formulations.Methods and ResultsThe impact of HDL on IRI was investigated using complementary in vivo, ex vivo and in vitro IRI models. Acute post-ischemic treatment with native HDL significantly reduced infarct size and cell death in the ex vivo, isolated heart (Langendorff) model and the in vivo model (-48%, p<0.01). Treatment with rHDL of basic formulation (apoAI + phospholipids) had a non-significant impact on cell death in vitro and on the infarct size ex vivo and in vivo. In contrast, rHDL containing S1P had a highly significant, protective influence ex vivo, and in vivo (-50%, p<0.01). This impact was comparable with the effects observed with native HDL. Pro-survival signaling proteins, Akt, STAT3 and ERK1/2 were similarly activated by HDL and rHDL containing S1P both in vitro (isolated cardiomyocytes) and in vivo.ConclusionHDL afford protection against IRI in a clinically relevant model (post-ischemia). rHDL is significantly protective if supplemented with S1P. The protective impact of HDL appears to target directly the cardiomyocyte.

Abstract W MP85: Prostacyclin Receptor Activation With MRE-269 Reduces Infarct Size and Improves Long-term Neurological Recovery Following Ischemic Stroke in Both Young and Aged Rats

Activation of the prostacyclin (PGI2) IP receptor is protective in brain ischemia. However, there is very limited information of the molecular mechanisms of protection and the feasibility to target this pathway in stroke. MRE-269, a highly selective PGI2/IP receptor agonist, has been recently discovered. This IP agonist has a long half-life in vivo and is currently in phase III clinical trials for pulmonary hypertension. We hypothesized that post-ischemic treatment with MRE-269 provides neuroprotection in a rat ischemic stroke model. Young male rats (3-4-month old) were subjected to middle cerebral artery occlusion (MCAO) for 90 min and treated intravenously with either vehicle (n=14) or MRE-269 (0.1, 0.25, 0.5, and 1 mg/kg, n=10-14/group) at the start of reperfusion. At 48 h post-MCAO, rats were sacrificed to determine infarct size, blood-brain barrier (BBB) damage (IgG extravasation), hemorrhagic transformation (brain hemoglobin levels), and matrix metalloproteinase (MMP)-9 activity. In a separate experiment, aged male rats (18-20-month old) underwent 90 min of MCAO and randomly selected to receive intravenously either vehicle (n=11) or MRE-269 (0.25 mg/kg, n=11) starting at 4.5 h post-MCAO. Additional doses were given every 12 h for the first 48 h, and then one injection daily for 7 days post-MCAO. The accelerating rotarod and the adhesive removal tests were conducted before and at 3, 7, 14 and 21 days after MCAO by an investigator blinded to treatment groups. Infarct volume was quantified by MRI at 48 h and 21 days post-MCAO. In young rats, MRE-269 dose-dependently reduced cortical infarct size. MRE-269-treated rats (0.25 mg/kg) had significantly reduced BBB damage and less hemorrhagic transformation. Compared with the vehicle group, MRE-269-treated animals showed a significant reduction in brain MMP-9 activity. In aged rats, MRE-269 treatment resulted in a significant long-term recovery in both locomotor and somatosensory functions following MCAO. Quantitative MRI data showed that MRE-269 significantly reduced infarct volume compared with vehicle-treated rats. Our data suggest that targeting the PGI2/IP receptor with MRE-269 is a novel strategy to reduce neurovascular injury and promote long-term neurological recovery in ischemic stroke.

Abstract T P85: Mammalian Target of Rapamycin (mTOR) Signaling Pathway Mediates Cerebral Ischemic Brain Damage

BACKGROUND: Mammalian target of rapamycin (mTOR) signaling regulates cell energy metabolism and cell proliferation. Recent studies have demonstrated that mTOR activation is associated with increased cardiac infarct volume and necroptosis. The role of mTOR in cerebral ischemia has not been studied. The aim of this study is to explore how mTOR pathway behavior after cerebral ischemia and whether inhibition of mTOR reduces or increases ischemic brain damage. METHODS: Ten minutes of global ischemia was induced in Wistar rats (2-3 months old). Animals were either treatment with mTOR inhibitor rapamycin (6 mg/kg) or its vehicle. Animal brains were harvested after 3 hrs, 16 hrs and 7 days for histopathology and protein analyses. Sham-operated non-ischemic rats were used as control. Rapamycin was i.p. injected 1 hr after reperfusion in 7-day subgroups and injected 7 days prior to ischemia in 3 and 16 hrs subgroups. RESULTS: 10 minutes of global ischemia caused neuronal damage to the striatum, hippocampal CA1, and neocortical regions at 7 days of reperfusion. Levels of p-mTOR, p-S6K were increased significantly after 3 and 16 hrs in both the hippocampus and cortex. In addition, p-Akt and cytochrome c were elevated in the hippocampi after 3 hrs, peaked at 16 hrs and remained elevated after 7 days of reperfusion. Post-ischemic treatment with rapamycin 1 hrs after reperfusion significantly reduced brain damage in the CA1 and cortical areas at 7 days of reperfusion. Levels of p-mTOR, p-S6K, p-Akt and cytochrome c were significantly suppressed by rapamycin in non-ischemic and ischemic animals. CONCLUSION: Cerebral ischemia activates mTOR signaling pathway and inhibition of mTOR activativity reduces ischemic brain damage.

Abstract T P239: Therapeutic Efficacy and Pharmacological Mechanisms of SP-8203 for Treatment of Cerebral Ischemia

In cerebral ischemia, neurons and glia are deteriorated by various mechanisms including excitotoxicity, oxidative stress and inflammatory responses. Thus, pharmacological blockade of multiple cytotoxic pathways would be a therapeutic strategy for the treatment of ischemic injury. We recently identified a novel multi-potent neuroprotectant SP-8203. Pharmacological efficacy and action mechanism of SP-8203 were evaluated in rat transient middle cerebral artery occlusion (MCAO). Post-ischemic treatment (i.v.) of SP-8203 reduced cerebral ischemic injury in a dose-dependent manner (0.03 ~ 10 mg/kg) and at clinically relevant therapeutic time window (up to 12 h after ischemia onset). Similar efficacy was also obtained in beagle dogs subjected to permanent MCAO. Although it did not ameliorate the excitotoxicity, SP-8203 markedly reduced ischemia-evoked oxidative stress via up-regulation of anti-oxidant enzymes, specifically Mn-SOD and Cu/Zn-SOD, but not catalase and glutathione reductase. SP-8203 also reduced the infiltration of ED-1-immunopositive monocytes and MPO-positive neutrophils into ischemic brain lesions of rats. Moreover, SP-8203 significantly reduced the release of pro-inflammatory cytokines/chemokines (e.g. IL-1beta, TNF-alpha, MCP-1) and also the expression of iNOS and resultant formation of nitrotyrosine. Early (3 h) thrombolysis with tPA restored perfusion and reduced infarction in embolic rat models. However, late 6-h tPA did not decrease infarction, but instead increased intracerebral hemorrhage and mortality. Interestingly, SP-8203 treatment at 1.5 h before late (6 h) tPA infusion markedly reduced tPA-evoked cerebral hemorrhage and mortality. Blood levels of MMPs were significantly correlated with the changes of hemorrhage and mortality. Taken together, SP-8203 has multiple neuroprotective activities in cerebral ischemia: up-regulation of anti-oxidant enzymes, reduction of inflammatory cells recruitment, and suppression of anti-inflammatory cytokines/chemokines and MMP expression. Thanks to the multiple neuroprotective mechanisms, SP-8203 could be a promising drug candidate for stroke treatment, especially in combination of tPA by extending therapeutic time window.

Empowering sonic hedgehog to rescue brain cells after ischemic stroke.

Ischemic stroke occurs when blood supply to the brain is interrupted. This can cause irreversible injury to the central nervous system (CNS) tissue. Each year in the United States almost 800,000 people experience a new or recurrent stroke. 15% of stroke patients die shortly after insult and only 10% recover completely, leaving the majority of surviving stroke patients with disabilities. Tissue-type plasminogen activator (tPA) is the only available therapy for stroke but its clinical use is limited because of associated danger of intracranial hemorrhage. Therefore, there is an emergent need for stroke therapeutics that are safe and effective when administered at a later time point after insult.

Argon: a novel therapeutic option to treat neuronal ischemia and reperfusion injuries?

Neuronal injury and neuroprotection: Ischemia and reperfusion injuries in neuronal cells such as acute ischemic stroke - represent the third leading cause of death in the world. Current therapeutic concepts mainly aim to re-establish cerebral blood flow within a time window of less than 3 hours with the goal of limiting secondary brain injury. Secondary brain injury of the “penumbra” develops exponentially, causing severe mental and physical disabilities. The resulting morbidity and mortality in patients of all ages leads to an enormous economic burden. Neurons are well-known to possess a limited potential to recover and regenerate their basic function once damaged. Therefore the protection and especially the therapy of neuronal injuries in cells and organ systems has emerged as a major focus of research in recent years. The aim is to maximize neuronal function not only by restoring sufficient blood flow to the areas at risk, but also by protecting neuronal cells with various novel interventions. Many of these interventions, such as intravascular cooling, focus on the reduction of neuronal metabolism in an effort to induce protection.

Post-stroke treatment with miR-181 antagomir reduces injury and improves long-term behavioral recovery in mice after focal cerebral ischemia

miR-181 has deleterious effects on stroke outcome, and reducing miR-181a levels prior to middle cerebral artery occlusion (MCAO) was shown previously to be protective. Here we tested the effect of post-ischemic treatment with miR-181a antagomir by intracerebroventricular and intravenous routes of administration on infarct size, neurological outcome, inflammatory response and long term behavioral outcome. Post-treatment with miR-181a antagomir significantly reduced infarction size, improved neurological deficits and reduced NF-κB activation, numbers of infiltrating leukocytes and levels of Iba1. Targets affected by miR-181a antagomir administered after stroke onset include BCL2 and X-linked inhibitor of apoptosis protein (XIAP). Post-treatment with miR-181a antagomir significantly improved behavioral outcome assessed by rotarod at one month. These findings indicate that post-treatment with miR-181a antagomir has neuroprotective effects against ischemic neuronal damage and neurological impairment in mice, and the protection is long lasting including recovery of motor function and coordination over one month. The ability to protect the brain with post-treatment with miR-181a antagomir with long lasting effect makes this a promising therapeutic target and may be an innovative and effective new approach for stroke therapy.

A Smoothened receptor agonist is neuroprotective and promotes regeneration after ischemic brain injury.

Ischemic stroke occurs as a result of blood supply interruption to the brain causing tissue degeneration, patient disabilities or death. Currently, treatment of ischemic stroke is limited to thrombolytic therapy with a narrow time window of administration. The sonic hedgehog (Shh) signaling pathway has a fundamental role in the central nervous system development, but its impact on neural cell survival and tissue regeneration/repair after ischemic stroke has not been well investigated. Here we report the neuroprotective properties of a small-molecule agonist of the Shh co-receptor Smoothened, purmorphamine (PUR), in the middle cerebral artery occlusion model of ischemic stroke. We found that intravenous administration of PUR at 6 h after injury was neuroprotective and restored neurological deficit after stroke. PUR promoted a transient upregulation of tissue-type plasminogen activator in injured neurons, which was associated with a reduction of apoptotic cell death in the ischemic cortex. We also observed a decrease in blood–brain barrier permeability after PUR treatment. At 14 d postinjury, attenuation of inflammation and reactive astrogliosis was found in PUR-treated animals. PUR increased the number of newly generated neurons in the peri-infarct and infarct area and promoted neovascularization in the ischemic zone. Notably, PUR treatment did not significantly alter the ischemia-induced level of Gli1, a Shh target gene of tumorigenic potential. Thus our study reports a novel pharmacological approach for postischemic treatment using a small-molecule Shh agonist, providing new insights into hedgehog signaling-mediated mechanisms of neuroprotection and regeneration after stroke.

HIF-1α signaling activation by post-ischemia treatment with astragaloside IV attenuates myocardial ischemia-reperfusion injury.

In this study, we evaluated the effect of astragaloside IV (Ast IV) post-ischemia treatment on myocardial ischemia-reperfusion (IR) injury (IRI). We also examined whether hypoxia inducible factor-1α (HIF-1α) and its downstream gene-inducible nitric oxide (NO) synthase (iNOS) play roles in the cardioprotective effect of Ast IV. Cultured cardiomyocytes and perfused isolated rat hearts were exposed to Ast IV during reperfusion in the presence or absence of the HIF-1α inhibitor 2-methoxyestradiol (2-MeOE2). The post-ischemia treatment with Ast IV protected cardiomyocytes from the apoptosis and death induced by simulated IRI (SIRI). Additionally, in cardiomyocytes, 2-MeOE2 and HIF-1α siRNA treatment each not only abolished the anti-apoptotic effect of post-ischemia treatment with Ast IV but also reversed the upregulation of HIF-1α and iNOS expression. Furthermore, after treatment with Ast IV, post-ischemic cardiac functional recovery and lactate dehydrogenase (LDH) release in the coronary flow (CF) were improved, and the myocardial infarct size was decreased. Moreover, the number of apoptotic cells was reduced, and the upregulation of the anti-apoptotic protein Bcl2 and downregulation of the pro-apoptotic protein Caspase3 were reversed. 2-MeOE2 reversed these effects of Ast IV on IR-injured hearts. These results suggest that post-ischemia treatment with Ast IV can attenuate IRI by upregulating HIF-1α expression, which transmits a survival signal to the myocardium.

Antidepressant fluvoxamine reduces cerebral infarct volume and ameliorates sensorimotor dysfunction in experimental stroke

The sigma-1 receptor has been reported to be associated with diverse biological activities including cellular differentiation, neuroplasticity, neuroprotection, and cognitive functioning of the brain. Fluvoxamine, one of the currently known antidepressants, is a sigma-1 receptor agonist; its effectiveness in treating acute cerebral ischemia has not been reported. We studied the in-vivo effects of this compound using an animal model of focal cerebral ischemia. Forty male Sprague-Dawley rats were subjected to right middle cerebral artery occlusion and assigned to five treatment groups (n=8 each). Postischemic neurological deficits and infarct volume were determined 24 h after stroke-inducing surgery. Significant reductions in infarct volume (total and cortical) were found in group 2 (fluvoxamine 20 mg/kg given 6 h before and immediately after ischemic onset) and group 3 (fluvoxamine given immediately after ischemic onset and 2 h later) compared with controls. Fluvoxamine induced significant amelioration of sensorimotor dysfunction, as indicated by the scores of forelimb and hindlimb placing tests. Moreover, NE-100, a selective sigma-1 receptor antagonist, completely blocked the neuroprotective effect of fluvoxamine. The present findings suggest that the sigma-1 receptor agonist fluvoxamine reduces infarct volume and ameliorates neurological impairment even on postischemic treatment. From the clinical viewpoint, fluvoxamine may be a promising new therapeutic approach for cerebral infarction.

Re: Yamashita J, Itoh M, Kuro T, Kobayashi Y, Ogata M, Takaoka M, and Matsumura Y (2001) Pre- or Post-Ischemic Treatment with a Novel Na+/Ca2+ Exchange Inhibitor, KB-R7943, Shows Renal Protective Effects in Rats with Ischemic Acute Renal Failure. J Pharmacol Exp Ther 296:412–419

Re: Yamashita J, Itoh M, Kuro T, Kobayashi Y, Ogata M, Takaoka M, and Matsumura Y (2001) Pre- or Post-Ischemic Treatment with a Novel Na⁺/Ca²⁺ Exchange Inhibitor, KB-R7943, Shows Renal Protective Effects in Rats with Ischemic Acute Renal Failure. <i>J Pharmacol Exp Ther</i> 296:412–419

Neuroprotective Effect of TAT-14-3-3ε Fusion Protein against Cerebral Ischemia/Reperfusion Injury in Rats

Stroke is the major cause of death and disability worldwide, and the thrombolytic therapy currently available was unsatisfactory. 14-3-3ε is a well characterized member of 14-3-3 family, and has been reported to protect neurons against apoptosis in cerebral ischemia. However, it cannot transverse blood brain barrier (BBB) due to its large size. A protein transduction domain (PTD) of HIV TAT protein, is capable of delivering a large variety of proteins into the brain. In this study, we generated a fusion protein TAT-14-3-3ε, and evaluated its potential neuroprotective effect in rat focal ischemia/reperfusion (I/R) model. Western blot analysis validated the efficient transduction of TAT-14-3-3ε fusion protein into brain via a route of intravenous injection. TAT-14-3-3ε pre-treatment 2 h before ischemia significantly reduced cerebral infarction volume and improved neurologic score, while post-treatment 2 h after ischemia was less effective. Importantly, pre- or post-ischemic treatment with TAT-14-3-3ε significantly increased the number of surviving neurons as determined by Nissl staining, and attenuated I/R-induced neuronal apoptosis as showed by the decrease in apoptotic cell numbers and the inhibition of caspase-3 activity. Moreover, the introduction of 14-3-3ε into brain by TAT-mediated delivering reduced the formation of autophagosome, attenuated LC3B-II upregulation and reversed p62 downregulation induced by ischemic injury. Such inhibition of autophagy was reversed by treatment with an autophagy inducer rapamycin (RAP), which also attenuated the neuroprotective effect of TAT-14-3-3ε. Conversely, autophagy inhibitor 3-methyladenine (3-MA) inhibited I/R-induced the increase in autophagic activity, and attenuated I/R-induced brain infarct. These results suggest that TAT-14-3-3ε can be efficiently transduced into brain and exert significantly protective effect against brain ischemic injury through inhibiting neuronal apoptosis and autophagic activation.

La atorvastatina protege las neuronas GABAérgicas y dopaminérgicas del sistema nigroestriatal en un modelo experimental de isquemia cerebral focal transitoria en ratas

Introduction: Cerebral ischemia is the third leading cause of death and the primary cause of permanent disability worldwide. Atorvastatin is a promising drug with neuroprotective effects that may be useful for the treatment of stroke. However, the effects of atorvastatin on specific neuronal populations within the nigrostriatal system following cerebral ischemia are unknown. Objective: To evaluate the effects of atorvastatin on dopaminergic and GABAergic neuronal populations in exofocal brain regions in a model of transient occlusion of the middle cerebral artery. Materials and methods: Twenty-eight male eight-week-old Wistar rats were used in this study. Both sham and ischemic rats were treated with atorvastatin (10 mg/kg) or carboxymethylcellulose (placebo) by gavage at 6, 24, 48 and 72 hours post-reperfusion. We analyzed the immunoreactivity of glutamic acid decarboxylase and tyrosine hydroxylase in the globus pallidus, caudate putamen and substantia nigra. Results: We observed neurological damage and cell loss in the caudate putamen following ischemia. We also found an increase in tyrosine hydroxylase immunoreactivity in the medial globus pallidus and substantia nigra reticulata, as well as a decrease in glutamic acid decarboxylase immunoreactivity in the lateral globus pallidus in ischemic animals treated with a placebo. However, atorvastatin treatment was able to reverse these effects, significantly decreasing tyrosine hydroxylase levels in the medial globus pallidus and substantia nigra reticulata and significantly increasing glutamic acid decarboxylase levels in the lateral globus pallidus. Conclusion: Our data suggest that post-ischemia treatment with atorvastatin can have neuro-protective effects in exofocal regions far from the ischemic core by modulating the GABAergic and dopaminergic neuronal populations in the nigrostriatal system, which could be useful for preventing neurological disorders.

Atorvastatin protects GABAergic and dopaminergic neurons in the nigrostriatal system in an experimental rat model of transient focal cerebral ischemia.

Cerebral ischemia is the third leading cause of death and the primary cause of permanent disability worldwide. Atorvastatin is a promising drug with neuroprotective effects that may be useful for the treatment of stroke. However, the effects of atorvastatin on specific neuronal populations within the nigrostriatal system following cerebral ischemia are unknown. To evaluate the effects of atorvastatin on dopaminergic and GABAergic neuronal populations in exofocal brain regions in a model of transient occlusion of the middle cerebral artery. Twenty-eight male eight-week-old Wistar rats were used in this study. Both sham and ischemic rats were treated with atorvastatin (10 mg/kg) or carboxymethylcellulose (placebo) by gavage at 6, 24, 48 and 72 hours post-reperfusion. We analyzed the immunoreactivity of glutamic acid decarboxylase and tyrosine hydroxylase in the globus pallidus, caudate putamen and substantia nigra. We observed neurological damage and cell loss in the caudate putamen following ischemia. We also found an increase in tyrosine hydroxylase immunoreactivity in the medial globus pallidus and substantia nigra reticulata, as well as a decrease in glutamic acid decarboxylase immunoreactivity in the lateral globus pallidus in ischemic animals treated with a placebo. However, atorvastatin treatment was able to reverse these effects, significantly decreasing tyrosine hydroxylase levels in the medial globus pallidus and substantia nigra reticulata and significantly increasing glutamic acid decarboxylase levels in the lateral globus pallidus. Our data suggest that post-ischemia treatment with atorvastatin can have neuro-protective effects in exofocal regions far from the ischemic core by modulating the GABAergic and dopaminergic neuronal populations in the nigrostriatal system, which could be useful for preventing neurological disorders.

Application of ultrasound technology in the study of ischemic postconditioning to protect testes from ischemia-reperfusion injury.

This study was designed to investigate the application of ultrasound technology in the study of ischemic postconditioning to protect testes from ischemia-reperfusion injury. Seventy-two big white rabbits were divided into mild ischemic groups (Group A: A0, A1, A2, A3), moderate ischemic groups (Group B: B0, B1, B2, B3) under ultrasound monitor, and control group (N = 8). Groups A0 and B0 received direct perfusion, while the other groups received a different short time filling/stopped filling treatment (15 s/15 s, 30 s/30 s, or 45 s/45 s) three times before complete perfusion. Each group received contrast-enhanced ultrasound before complete filling. At 3 days after perfusion, the testicular tissue was removed for biopsy. The parameters of testicular contrast in pre-reperfusion groups A and B differed significantly from those of their corresponding control groups (P < 0.05). The changes in testis-related pathological indicators in groups A1 and A2 were more significant than those of group A0 (P < 0.05), and changes in group B2 were more obvious than those of group B0 (P < 0.05). There were no statistically significant differences in the comparison of other indicators between the corresponding groups (P > 0.05). Ultrasound technology can help build different degree models of ischemic testes and predict the protective effect of post-ischemic treatment.

Continuous oral administration of atorvastatin ameliorates brain damage after transient focal ischemia in rats

AimsPre-treatment with statins is known to ameliorate ischemic brain damage after experimental stroke, and is independent of cholesterol levels. We undertook pre- vs post-ischemic treatment with atorvastatin after focal cerebral ischemia in rats. Main methodsMale Sprague–Dawley rats underwent transient 90-min middle cerebral artery occlusion (MCAO). Atorvastatin (20mg/kg/day) or vehicle was administered orally. Rats were divided into vehicle-treated, atorvastatin pre-treatment, atorvastatin post-treatment, and atorvastatin continuous-treatment groups. In the pre-treatment, rats were given atorvastatin or vehicle for 7days before MCAO. In the post-treatment, rats received atorvastatin or vehicle for 7days after MCAO. Measurement of infarct volume, as well as neurological and immunohistochemical assessments, were done 24h and 7days after reperfusion. Key findingsEach atorvastatin-treated group demonstrated significant reductions in infarct and edema volumes compared with the vehicle-treated group 24h after reperfusion. Seven days after reperfusion, infarct volumes in the post-treatment group and continuous-treatment group (but not the pre-treatment group) were significantly smaller than in the vehicle-treated group. Only the continuous-treatment group had significantly improved neurological scores 7days after reperfusion compared with the vehicle group. Post-treatment and continuous-treatment groups had significantly decreased lipid peroxidation, oxidative DNA damage, microglial activation, expression of tumor necrosis factor-alpha, and neuronal damage in the cortical ischemic boundary area after 7days of reperfusion. SignificanceThese results suggest that continuous oral administration (avoiding withdrawal) with statins after stroke may reduce the extent of post-ischemic brain damage and improve neurological outcome by inhibiting oxidative stress and inflammatory responses.

Neurovascular protection by post‐ischemic intravenous injections of the lipoxin A4 receptor agonist, BML‐111, in a rat model of ischemic stroke

Resolution of inflammation is an emerging new strategy to reduce damage following ischemic stroke. Lipoxin A4 (LXA4 ) is an anti-inflammatory, pro-resolution lipid mediator with high affinity binding to ALX, the lipoxin A4 receptor. Since LXA4 is rapidly inactivated, potent analogs have been created, including the ALX agonist BML-111. We hypothesized that post-ischemic intravenous administration of BML-111 would provide protection to the neurovascular unit and reduce neuroinflammation in a rat stroke model. Animals were subjected to 90 min of middle cerebral artery occlusion (MCAO) and BML-111 was injected 100 min and 24 h after stroke onset and animals euthanized at 48 h. Post-ischemic treatment with BML-111 significantly reduced infarct size, decreased vasogenic edema, protected against blood-brain barrier disruption, and reduced hemorrhagic transformation. Matrix metalloproteinase-9 and matrix metalloproteinase-3 were significantly reduced following BML-111 treatment. Administration of BML-111 dramatically decreased microglial activation, as seen with CD68, and neutrophil infiltration and recruitment, as assessed by levels of myeloperoxidase and intracellular adhesion molecule-1. The tight junction protein zona occludens-1 was protected from degradation following treatment with BML-111. These results indicate that post-ischemic activation of ALX has pro-resolution effects that limit the inflammatory damage in the cerebral cortex and helps maintain blood-brain barrier integrity after ischemic stroke.

Capacity of HSYA to inhibit nitrotyrosine formation induced by focal ischemic brain injury

Peroxynitrite-mediated protein tyrosine nitration represents a crucial pathogenic mechanism of stroke. Hydroxysafflor yellow A (HSYA) is the most important active component of the safflower plant. Here we assess the neuroprotective efficacy of HSYA and investigate the mechanism through anti-nitrative pathway.Rats were subjected to 60-min ischemia followed by reperfusion. HSYA (2.5–10mg/kg) was injected at 1h after ischemia onset. Other groups received HSYA (10mg/kg) treatment at 3–9h after onset. Infarct volume, brain edema, and neurological score were evaluated at 24h after ischemia. Nitrotyrosine and inducible NO synthase (iNOS) expression, as well as NO level (nitrate/nitrite) in ischemic cortex was examined within 24h after ischemia. The ability of HSYA to scavenge peroxynitrite was evaluated in vitro.Infarct volume was significantly decreased by HSYA (P<0.05), with a therapeutic window of 3h after ischemia at dose of 10mg/kg. HSYA treatment also reduced brain edema and improved neurological score (P<0.05). Nitrotyrosine formation was dose- and time-dependently inhibited by HSYA. The time window of HSYA in decreasing protein tyrosine nitration paralleled its action in infarct volume. HSYA also greatly reduced iNOS expression and NO content at 24h after ischemia, suggesting prevention of peroxynitrite generation from iNOS. In vitro, HSYA blocked authentic peroxynitrite-induced tyrosine nitration in bovine serum albumin and primary cortical neurons.Collectively, our results indicated that post-ischemic HSYA treatment attenuates brain ischemic injury which is at least partially due to reducing nitrotyrosine formation, possibly by the combined mechanism of its peroxynitrite scavenging ability and its reduction in iNOS production.

Progressive endothelin-1 gene activation initiates chronic/end-stage renal disease following experimental ischemic/reperfusion injury

This study assessed whether endothelin-1 (ET1) helps mediate post-ischemic acute kidney injury (AKI) progression to chronic kidney disease (CKD). The impact(s) of potent ETA or ETB receptor-specific antagonists (Atrasentan and BQ-788, respectively) on disease progression were assessed 24 hours or 2 weeks following 30 minutes of unilateral ischemia in CD-1 mice. Unilateral ischemia caused progressive renal ET-1 protein/mRNA increases with concomitant ETA, but not ETB, mRNA elevations. Extensive histone remodeling consistent with gene activation and increased RNA polymerase II binding occurred at the ET-1 gene. Unilateral ischemia produced progressive renal injury as indicated by severe histologic injury and a 40% loss of renal mass. Pre- and post-ischemia or just post-ischemic treatment with Atrasentan conferred dramatic protective effects such as decreased tubule/microvascular injury, normalized tissue lactate, and total preservation of renal mass. Nuclear KI-67 staining was not increased by Atrasentan, implying that increased tubule proliferation was not involved. Conversely, ETB blockade had no protective effect. Thus, our findings provide the first evidence that ET-1 operating through ETA can play a critical role in ischemic AKI progression to CKD. Blockade of ETA provided dramatic protection, indicating the functional significance of these results.