losartan-potassium and Ischemic-Attack--Transient

Topics: Aged; Biomarkers; C-Reactive Protein; Erythropoietin; Female; Humans; Inflammation; Ischemic Attack, Transient; Male; Middle Aged; Peroxiredoxins; Recurrence; Sensitivity and Specificity; Stroke, Lacunar

In patients with acute symptomatic moyamoya (<2 weeks), the feasibility of a combination therapy of multiple burr hole procedure under local anesthesia and intravenous erythropoietin pretreatment was assessed. We also identified the factors associated with transdural revascularization.. In this prospective single-arm study, perfusion-impaired patients presenting with transient ischemic attack or acute cerebral infarction were assessed. Combination therapy was performed to patients lacking transdural collaterals. Primary outcomes were evaluated clinically with modified Rankin Scale scores and radiologically with revascularization success (transhemispheric, trans-burr hole, and sufficient revascularizations [filling ≥33% of ipsilateral supratentorium]) at 6 months. Treatment-related adverse events were analyzed in 3 phases: pre burr hole, post burr hole, and after-discharge as secondary outcome. Factors associated with sufficient revascularization were investigated.. Fifty hemispheres from 37 patients were included. Compared with discharge, modified Rankin Scale score at 6 months significantly improved (2.0 [0.0-5.0] versus 1.0 [0.0-4.0];. Combination therapy allows safe and effective revascularization in moyamoya patients with acute ischemic presentation.. URL: https://www.clinicaltrials.gov. Unique identifier: NCT03162588.

Topics: Acute Disease; Adult; Cerebral Infarction; Cerebral Revascularization; Combined Modality Therapy; Erythropoietin; Feasibility Studies; Female; Humans; Ischemic Attack, Transient; Male; Middle Aged; Moyamoya Disease; Odds Ratio; Prospective Studies; Trephining

Preconditioning (PC) using a preceding sublethal ischemic insult is an attractive strategy for protecting neurons by inducing ischemic tolerance in the brain. Although the underlying molecular mechanisms have been extensively studied, almost all studies have focused on neurons. Here, using a middle cerebral artery occlusion model in mice, we show that astrocytes play an essential role in the induction of brain ischemic tolerance. PC caused activation of glial cells without producing any noticeable brain damage. The spatiotemporal pattern of astrocytic, but not microglial, activation correlated well with that of ischemic tolerance. Interestingly, such activation in astrocytes lasted at least 8 weeks. Importantly, inhibiting astrocytes with fluorocitrate abolished the induction of ischemic tolerance. To investigate the underlying mechanisms, we focused on the P2X7 receptor as a key molecule in astrocyte-mediated ischemic tolerance. P2X7 receptors were dramatically upregulated in activated astrocytes. PC-induced ischemic tolerance was abolished in P2X7 receptor knock-out mice. Moreover, our results suggest that hypoxia-inducible factor-1α, a well known mediator of ischemic tolerance, is involved in P2X7 receptor-mediated ischemic tolerance. Unlike previous reports focusing on neuron-based mechanisms, our results show that astrocytes play indispensable roles in inducing ischemic tolerance, and that upregulation of P2X7 receptors in astrocytes is essential.

Topics: Animals; Astrocytes; Brain Ischemia; Erythropoietin; Hypoxia-Inducible Factor 1, alpha Subunit; Infarction, Middle Cerebral Artery; Ischemic Attack, Transient; Ischemic Preconditioning; Mice; Mice, Inbred C57BL; Mice, Knockout; Microglia; Receptors, Purinergic P2X7

OBJECT.: There is an unmet clinical need to develop neuroprotective agents for neurosurgical and endovascular procedures that require transient cerebral artery occlusion. The aim in this study was to explore the effects of a single dose of recombinant human erythropoietin (rhEPO) before middle cerebral artery (MCA) occlusion in a focal cerebral ischemia/reperfusion model.. Twenty-eight adult male Wistar rats were subjected to right MCA occlusion via the intraluminal thread technique for 60 minutes under continuous cortical perfusion monitoring by laser Doppler flowmetry. Rats were divided into 2 groups: control and treatment. In the treated group, rhEPO (1000 IU/kg intravenously) was administered 10 minutes before the onset of the MCA ischemia. At 24-hour reperfusion, animals were examined for neurological deficits, blood samples were collected, and animals were killed. The following parameters were evaluated: brain infarct volume, ipsilateral hemispheric edema, neuron-specific enolase plasma levels, parenchyma histological features (H & E staining), Fluoro-Jade-positive neurons, p-Akt and total Akt expression by Western blot analysis, and p-Akt-positive nuclei by immunohistochemical investigation.. Infarct volume and Fluoro-Jade staining of degenerating neurons in the infarct area did not vary between groups. The severity of neurological deficit (p < 0.001), amount of brain edema (78% reduction in treatment group, p < 0.001), and neuron-specific enolase plasma levels (p < 0.001) were reduced in the treatment group. Perivascular edema was histologically less marked in the treatment group. No variations in the expression or localization of p-Akt were seen.. Administration of rhEPO before the onset of 60-minute transient MCA ischemia protected the brain from this insult. It is unlikely that rhEPO pretreatment leads to direct neuronal antiapoptotic effects, as supported by the lack of Akt activation, and its benefits are most probably related to an indirect effect on brain edema as a consequence of blood-brain barrier preservation. Although research on EPO derivatives is increasing, rhEPO acts through distinct neuroprotective pathways and its clinical safety profile is well known. Clinically available rhEPO is a potential therapy for prevention of neuronal injury induced by transitory artery occlusion during neurovascular procedures.

Topics: Animals; Apoptosis; Blood-Brain Barrier; Brain; Erythropoietin; Infarction, Middle Cerebral Artery; Ischemic Attack, Transient; Male; Neuroprotective Agents; Phosphopyruvate Hydratase; Phosphorylation; Proto-Oncogene Proteins c-akt; Rats; Rats, Wistar

Therapeutic agents that restore the inhibitory actions of γ-amino butyric acid (GABA) by modulating intracellular chloride concentrations will provide novel avenues to treat stroke, chronic pain, epilepsy, autism, and neurodegenerative and cognitive disorders. During development, upregulation of the potassium-chloride co-transporter KCC2, and the resultant switch from excitatory to inhibitory responses to GABA guide the formation of essential inhibitory circuits. Importantly, maturation of inhibitory mechanisms is also central to the development of excitatory circuits and proper balance between excitatory and inhibitory networks in the developing brain. Loss of KCC2 expression occurs in postmortem samples from human preterm infant brains with white matter lesions. Here we show that late gestation brain injury in a rat model of extreme prematurity impairs the developmental upregulation of potassium chloride co-transporters during a critical postnatal period of circuit maturation in CA3 hippocampus by inducing a sustained loss of oligomeric KCC2 via a calpain-dependent mechanism. Further, administration of erythropoietin (EPO) in a clinically relevant postnatal dosing regimen following the prenatal injury protects the developing brain by reducing calpain activity, restoring oligomeric KCC2 expression and attenuating KCC2 fragmentation, thus providing the first report of a safe therapy to address deficits in KCC2 expression. Together, these data indicate it is possible to reverse abnormalities in KCC2 expression during the postnatal period, and potentially reverse deficits in inhibitory circuit formation central to cognitive impairment and epileptogenesis.

Topics: Age Factors; Animals; Animals, Newborn; Brain-Derived Neurotrophic Factor; Carbazoles; Enzyme Inhibitors; Erythropoietin; Excitatory Amino Acid Agonists; Female; Gene Expression Regulation, Developmental; Hippocampus; In Vitro Techniques; Indole Alkaloids; Ischemic Attack, Transient; K Cl- Cotransporters; Male; N-Methylaspartate; Neuroprotective Agents; Pregnancy; Rats; Rats, Sprague-Dawley; Symporters

Many studies have demonstrated beneficial effects of either erythropoietin (EPO) or endothelial progenitor cell (EPC) treatment in cerebral ischemia. To improve post-ischemic tissue repair, we investigated the effect of systemic administration of endothelial colony-forming cells (ECFCs), considered as relevant endothelial progenitors due to their specific vasculogenic activity, in the presence or absence of EPO, on functional recovery, apoptosis, angiogenesis, and neurogenesis in a transient focal cerebral ischemia model in the adult rat.. Experimental study.. The rats were divided into four groups 24 hours after ischemia,, namely control, ECFCs, EPO, and ECFCs+EPO, and received a single intravenous injection of ECFCs (5 × 10(6) cells) and/or intraperitoneal administration of EPO (2500 UI/kg per day for 3 days).. Infarct volume, functional recovery, apoptosis, angiogenesis, and neurogenesis were assessed at different time points after ischemia.. The combination of EPO and ECFCs was the only treatment that completely restored neurological function. The ECFCs+EPO treatment was also the most effective to decrease apoptosis and to increase angiogenesis and neurogenesis in the ischemic hemisphere compared to controls and to groups receiving ECFCs or EPO alone.. These results suggest that EPO could act in a synergistic way with ECFCs to potentiate their therapeutic benefits.

Topics: Animals; Apoptosis; Brain; Brain-Derived Neurotrophic Factor; Combined Modality Therapy; Endothelial Cells; Erythropoietin; Infarction, Middle Cerebral Artery; Ischemic Attack, Transient; Male; Neovascularization, Physiologic; Neurogenesis; Neuroprotective Agents; Rats; Rats, Sprague-Dawley; Recovery of Function; Stem Cell Transplantation; Stem Cells; Vascular Endothelial Growth Factor A

Cerebral ischemia-reperfusion (I/R) injury induces secondary cerebral damage. As drugs for treating this type of injury have shown poor efficacy and adverse side effects in clinical trials, a novel therapeutic strategy has been long awaited. In this study, we focused on the disruption of the blood-brain barrier after stroke, and applied a liposomal drug delivery system (DDS) designed to enhance the pharmacological effect of the neuroprotectant and to avoid side effects. PEGylated liposomes were injected at varying time after the start of reperfusion in transient middle cerebral artery occlusion (t-MCAO) model rats. The results showed PEGylated liposomes accumulated in the ischemic hemisphere at an early stage after reperfusion and were retained in the lesion for at least 24h after injection. We also investigated the effectiveness of asialo-erythropoietin (AEPO)-modified PEGylated liposomes (AEPO-liposomes) in treating the cerebral I/R injury. AEPO-liposome treatment significantly reduced TTC-defined cerebral legion following cerebral I/R injury, and ameliorated motor function compared with vehicle and AEPO treatment. In conclusion, these results indicate that AEPO-liposomes are a promising liposomal formulation for protecting the brain from I/R injury, and that this liposomal DDS has potential as a novel strategy for the treatment of cerebral I/R injury.

Topics: Animals; Apoptosis; Asialoglycoproteins; Blood-Brain Barrier; Cell Culture Techniques; Cell Survival; Disease Models, Animal; Drug Delivery Systems; Erythropoietin; In Situ Nick-End Labeling; Ischemic Attack, Transient; Liposomes; Male; Neuroprotective Agents; PC12 Cells; Rats; Rats, Wistar; Reperfusion Injury; Tissue Distribution

Erythropoietin has been reported to improve the behavioral performance of healthy mice in tests thought to depend on synaptic plasticity in the CA1 region of the hippocampus. We show here for the first time that a single injection of the erythropoietin analog darbepoetin alfa reverses pre-existing cognitive deficits in adult rats that had been subjected to transient global ischemia produced by four-vessel occlusion (4-VO). Quantification of neuronal density demonstrated that 12 min of 4-VO selectively killed more than 90% of CA1 neurons in the dorsal hippocampus. Rats that had sustained a bilateral loss of hippocampal CA1 neurons in this range (4-VO rats) displayed more errors and longer escape latencies in the Barnes maze compared with sham-operated controls. A single injection of darbepoetin alfa (5000 U/kg i.p.) 4 h before behavioral testing decreased deficits in escape latency for 4-VO rats but not sham-operated controls. This improvement in spatial working memory performance was correlated with increased levels of nitric-oxide metabolites in the ventral hippocampus. Systemic administration of the nitric-oxide synthase inhibitor N(G)-nitro-L-nitro-arginine methyl ester reversed the increase in nitric-oxide metabolites and improvements in spatial working memory produced by darbepoetin alfa (5000 U/kg, i.p.) at a dose (10 mg/kg, i.p.) that did not impair the spatial working memory performance of intact rats. Taken together, these findings suggest that darbepoetin alfa reverses pre-existing spatial working memory deficits resulting from transient global ischemia by increasing the activity of nitric-oxide synthase, an enzyme implicated in synaptic plasticity.

Topics: Animals; CA1 Region, Hippocampal; Darbepoetin alfa; Erythropoietin; Hippocampus; Ischemic Attack, Transient; Male; Maze Learning; Memory Disorders; Memory, Short-Term; Neuroprotective Agents; NG-Nitroarginine Methyl Ester; Nitrates; Nitric Oxide Synthase; Nitrites; Rats; Rats, Sprague-Dawley

Systemic administration of high-dose recombinant human erythropoietin (rhEPO) is known to attenuate ischemic injury. However, high-dose rhEPO might aggravate ischemic lesions by increasing blood viscosity because of its erythropoietic effects. Asialoerythropoietin (asialoEPO), an EPO derivative with an extremely short plasma half-life, has considerably lesser erythropoietic effect than that of naive EPO. We attempted to determine whether asialoEPO exerts the same neuroprotective effect as naive EPO in a gerbil transient forebrain ischemia model.. Transient occlusion of both the common carotid arteries was performed in 23 adult gerbils. The drugs (asialoEPO or rhEPO, 10 U/g bodyweight) or phosphate-buffered saline (PBS) were injected intraperitoneally at three times (3 hours before, immediately after, and 24 hours after the ischemic insult). Learning and retention tests were performed on days 6 and 7, respectively, and histological analyses were performed on day 7.. Animals treated with asialoEPO and rhEPO showed significant neurological improvement compared to the PBS-treated animals. The number of viable neurons in the CA1 field of the rhEPO-treated (103.57 ± 27.90 cells/mm) and asialoEPO-treated (144.99 ± 34.87 cells/mm) animals was higher than that of the PBS-treated animals (19.53 ± 3.79 cells/mm). Terminal dinucleotidyltransferase-mediated UTP end labeling-positive cells were significantly lower in the rhEPO-treated (33.40 ± 8.13 cells/mm) and asialoEPO-treated (29.28 ± 14.91 cells/mm) animals than in the PBS-treated animals (76.67 ± 8.14 cells/mm). AsialoEPO treatment did not have any effect on erythropoiesis.. Multiple dosing of asialoEPO, like EPO, could protect the hippocampal CA1 neurons from ischemic damage without affecting erythropoiesis.

Topics: Animals; Asialoglycoproteins; Avoidance Learning; CA1 Region, Hippocampal; Carotid Artery Diseases; Cell Count; Cell Death; Chromatography, High Pressure Liquid; Disease Models, Animal; Dose-Response Relationship, Drug; Drug Administration Schedule; Erythropoietin; Gerbillinae; In Situ Nick-End Labeling; Ischemic Attack, Transient; Neurons; Neuroprotective Agents; Prosencephalon

The objectives of the present study were to: (1) noninvasively identify white matter reorganization and monitor its progress within 6 weeks after the onset of stroke; and (2) quantitatively investigate the effect of recombinant human erythropoietin treatment on this structural change using in vivo measurement of diffusion anisotropy.. Male Wistar rats were subjected to middle cerebral artery occlusion and treated with recombinant human erythropoietin intraperitoneally at a dose of 5000 U/kg of body weight (n=11) or the same volume of saline (n=7) daily for 7 days starting 24 hours after middle cerebral artery occlusion. MRI measurements of T2- and diffusion-weighted images and cerebral blood flow were performed and neurological severity score was assessed at 1 day and weekly for 6 weeks after middle cerebral artery occlusion. Luxol fast blue and Bielschowsky staining were used to demonstrate myelin and axons, respectively.. White matter reorganization occurred along the ischemic lesion boundary after stroke. The region of white matter reorganization seen on the tissue slice coincided with the elevated area on the fractional anisotropy map, which can be accurately identified. The increase in elevated fractional anisotropy pixels corresponded with progress of white matter reorganization and was associated with improvement of neurological function. Treatment with recombinant human erythropoietin after stroke significantly enhanced white matter reorganization, restored local cerebral blood flow, and expedited functional recovery.. White matter reorganization can be detected by fractional anisotropy. Elevated fractional anisotropy pixels may be a good MRI index to stage white matter remodeling and predict functional outcome.

Topics: Animals; Anisotropy; Axons; Brain; Diffusion Magnetic Resonance Imaging; Erythropoietin; Histocytochemistry; Humans; Image Processing, Computer-Assisted; Infarction, Middle Cerebral Artery; Ischemic Attack, Transient; Male; Myelin Sheath; Rats; Rats, Wistar; Recombinant Proteins; Recovery of Function

This study examines the efficacy of puerarin, a drug used in traditional Chinese medicine, in attenuating ischemic brain injury after cerebral ischemia and reperfusion, and explores possible mechanisms underlying neuroprotective effects.. The animal model of ischemia/reperfusion injury was induced by middle cerebral artery occlusion for 2 hours followed by up to 72 hour reperfusion. The rats were randomly assigned into four groups (n=6/group): puerarin at 100, 200 and 400 mg/kg or saline, administered intraperitoneally. Neurological outcome and infarct volume by 2% triphenyl tetrazolium chloride staining were determined 72 hours after reperfusion. Terminal deoxynucleotidyl transferase biotin-dUTP nick end labeling staining was used to detect the cell damage of brains (n=5/group). Erythropoietin activation was detected by enzyme-linked immunosorbent assay (n=5/group).. Compared with the vehicle saline group, puerarin decreased infarction volume at doses of 200 mg/kg (p=0.045) and 400 mg/kg (p=0.0002), but not at 100 mg/kg (p=0.387). Functional neurological outcome was improved with puerarin at 400 mg/kg (p=0.015), but not at 100 mg/kg (p=0.68) or 200 mg/kg (p=0.056). Puerarin significantly decreased the terminal deoxynucleotidyl transferase biotin-dUTP nick end labeling staining cells compared with the vehicle group 4, 24 and 72 hours after reperfusion. The erythropoietin activity was higher in puerarin treated group compared with the vehicle group.. Puerarin has neuroprotection effects in rats at doses of 200 and 400 mg/kg, administered intraperitoneally after transient middle cerebral artery occlusion which may be partly due to activation of erythropoietin activity.

Topics: Analysis of Variance; Animals; Apoptosis; Behavior, Animal; Brain Injuries; Disease Models, Animal; Dose-Response Relationship, Drug; Enzyme-Linked Immunosorbent Assay; Erythropoietin; Gene Expression Regulation; In Situ Nick-End Labeling; Ischemic Attack, Transient; Isoflavones; Male; Neurologic Examination; Rats; Rats, Sprague-Dawley; Time Factors; Vasodilator Agents

This study was performed to test whether systemically administered erythropoietin (EPO) could attenuate the blood-brain barrier (BBB) disruption in focal ischemia. Rats were injected intraperitoneally with 2,500 IU/kg of recombinant human EPO or normal saline 24 h before middle cerebral artery (MCA) occlusion. The transfer coefficient (Ki) of 14C-alpha-aminoisobutyric acid was determined to measure the degree of BBB disruption 1 h after MCA occlusion. In the control animals, the Ki of the ischemic cortex (IC) was significantly higher than that of the contralateral cortex (CC; +128%, p = 0.0002). In the EPO-treated animals, the Ki of the IC was not significantly different from that of the CC and was significantly lower (-44%, p = 0.003) than that of the control animals. Our data suggest that MCA occlusion increased BBB disruption, and the disruption was attenuated with EPO pretreatment.

Topics: Aminoisobutyric Acids; Animals; Blood-Brain Barrier; Capillary Permeability; Cerebral Cortex; Erythropoietin; Infarction, Middle Cerebral Artery; Injections, Intraperitoneal; Ischemic Attack, Transient; Male; Rats; Rats, Wistar; Recombinant Proteins

Many studies showed beneficial effects of either erythropoietin (EPO) or mesenchymal stem cells (MSCs) treatment in cerebral ischemia. In addition to a neuroprotective role, not only EPO but also MSC favors neurogenesis and functional recovery. In an attempt to further improve postischemic tissue repair, we investigated the effect of a systemic administration of MSC, in the presence or not of EPO, on neurogenesis and functional recovery in a transient focal cerebral ischemia model in the adult rat. Twenty-four hours after ischemia, the rats were divided into four groups, namely vehicle, MSC, EPO, and MSC+EPO, and received a single intravenous injection of MSC (2 x 10(6) cells) and/or a repeated intraperitoneal administration of EPO (1,000 UI/kg) for 3 days. The lesion volume, the MSC outcome, neurogenesis, and functional recovery were assessed 51 days after ischemia. The results showed that cellular proliferation and neurogenesis were increased along the lateral ventricle wall in the MSC+EPO group, whereas no significant effect was observed in groups receiving MSC or EPO alone. This effect was accompanied by an improvement of mnesic performances. Mesenchymal stem cells expressing neuronal or glial markers were detected in the ischemic hemisphere. These results suggest that EPO could act in a synergistic way with MSC to potentiate the postischemic neurogenesis.

Topics: Animals; Cell Differentiation; Cell Proliferation; Erythropoietin; Ischemic Attack, Transient; Mesenchymal Stem Cell Transplantation; Mesenchymal Stem Cells; Neuroglia; Neurons; Rats; Recombinant Proteins

The signal transducers and activators of transcription (STAT) proteins are a group of transcriptional factors. Among them, STAT5 initiates a pro-survival signaling cascade. So far, little has been known about the role of STAT5 in cerebral ischemia and reperfusion. This study examines the phosphorylation status of STAT5 in hippocampal CA1 in the early stage after transient global cerebral ischemia in rats. Our data show that the phosphorylation of STAT5 was increased in hippocampal CA1 at 1h and 3h ischemia. Taking advantage of the neuroprotective effect of erythropoietin (EPO) in CA1, we further demonstrated that the administration of EPO enhanced the phosphorylation of STAT5, with SATA5a being phosphorylated earlier. The enhanced phosphorylation of STAT5 in the EPO-treated group was accompanied by the upregulation of STAT5 downstream gene products, Bcl-xL and XIAP. Consequently, ischemic CA1 neuronal damage was attenuated by the administration of EPO. Both the enhancement of STAT5 phosphorylation and the neuroprotection rendered by EPO were blocked by Tyrphostin, a selective inhibitor for Janus kinase 2, which is an upstream kinase of STAT5. These findings suggest an association between the activation of STAT5 and CA1 neuronal survival after cerebral ischemia.

Topics: Animals; Apoptosis; bcl-X Protein; Blotting, Western; Cell Death; Erythropoietin; Hippocampus; Immunoprecipitation; In Situ Nick-End Labeling; Ischemic Attack, Transient; Janus Kinase 2; Male; Neurons; Neuroprotective Agents; Phosphorylation; Rats; Rats, Sprague-Dawley; Signal Transduction; STAT5 Transcription Factor; X-Linked Inhibitor of Apoptosis Protein

Recombinant human erythropoietin (rhEPO), a neurovascular protective agent, therapeutically supports angiogenesis after stroke by enhancing endogenous up-regulation of vascular endothelial growth factor (VEGF). Increased VEGF expression has been characterized to negatively impact the integrity of the blood brain barrier (BBB), causing brain edema and secondary injury. The present study investigated the rhEPO-induced BBB protection after stroke and how it might be achieved by affecting VEGF pathway. rhEPO treatment (5,000 U/kg, i.p., 30 min before stroke and once a day for three days after stroke) reduced Evans blue leakage and brain edema after ischemia. The expression of the BBB integrity markers, occludin, alpha-catenin and beta-catenin, in the brain was preserved in animals received rhEPO. rhEPO up-regulated VEGF expression; however, the expression of VEGF receptor-2 (fetal liver kinase receptor, Flk-1) was significantly reduced in rhEPO-treated animals three days after stroke. We propose that, disregarding increased VEGF levels, rhEPO protects against ischemia-induced BBB damage at least partly by down-regulating Flk-1 expression and the response to VEGF signaling in the acute phase after stroke.

Topics: Animals; Blood-Brain Barrier; Brain Edema; Cerebrovascular Circulation; Down-Regulation; Erythropoietin; Evans Blue; Fluorescent Antibody Technique; Infarction, Middle Cerebral Artery; Ischemic Attack, Transient; Male; Membrane Proteins; Mice; Microscopy, Confocal; Occludin; Recombinant Proteins; Stroke; Vascular Endothelial Growth Factor Receptor-2

Ischemic preconditioning (IP) protects the brain from subsequent, prolonged, and lethal ischemia in experimental studies. Erythropoietin (EPO) participates in the brain's intrinsic response to injury and may play a role in preconditioning. By using a middle cerebral artery occlusion (MCAo) model of transient ischemic attack (TIA), we sought to determine whether EPO is required for IP in the protective response against focal ischemic stroke. Rats underwent three 10-min MCA occlusions or sham surgery. Three days later, animals underwent 2 hr of MCAo and 22 hr of reperfusion. Experimental TIAs reduced infarct volumes by 55% (P < 0.05), inhibited DNA fragmentation, and improved neurological outcome by 50% (P < 0.05) after ischemic stroke. EPO and its receptor were up-regulated by IP in the ipsilateral hemisphere by 24 hr after IP, before ischemic stroke and soluble EPO receptor attenuated neuroprotection by IP (88% reduction, P < 0.05). Pretreatment with the PI-3 kinase inhibitor wortmannin abolished the protective effect of IP against ischemic injury (P < 0.05). IP may be mediated in part by EPO through a PI-3 kinase pathway.

Topics: Animals; Enzyme Inhibitors; Erythropoietin; Glial Fibrillary Acidic Protein; Immunohistochemistry; In Situ Nick-End Labeling; Ischemic Attack, Transient; Ischemic Preconditioning; Male; Phosphatidylinositol 3-Kinases; Phosphoinositide-3 Kinase Inhibitors; Rats; Rats, Wistar; Receptors, Erythropoietin; Signal Transduction

The widely prescribed drug desferrioxamine is a known activator of the hypoxia-inducible transcription factor 1 (HIF-1) and the subsequent transcription of erythropoietin. In the brain, HIF-1 is a master switch of the transcriptional response to hypoxia, whereas erythropoietin is a potent neuroprotectant. The authors show that desferrioxamine dose-dependently and time-dependently induces tolerance against focal cerebral ischemia in rats and mice, and against oxygen-glucose deprivation in purified cortical neurons. Desferrioxamine induced HIF-1 DNA binding and transcription of erythropoietin in vivo, the temporal kinetics of which were congruent with tolerance induction. Desferrioxamine is a promising drug for the induction of tolerance in humans when ischemia can be anticipated.

Topics: Animals; Cell Survival; Cells, Cultured; Cerebral Cortex; Constriction; Cycloheximide; Deferoxamine; DNA-Binding Proteins; Dose-Response Relationship, Drug; Embryo, Mammalian; Erythropoietin; Gene Expression; Glucose; Hypoxia-Inducible Factor 1; Hypoxia-Inducible Factor 1, alpha Subunit; Iron Chelating Agents; Ischemic Attack, Transient; Male; Middle Cerebral Artery; Neurons; Nuclear Proteins; Oxygen; Protein Synthesis Inhibitors; Rats; Rats, Wistar; Reperfusion; Thiazoles; Thiazolidinediones; Time Factors; Transcription Factors

Erythropoietin (EPO) produced by the kidney and the liver (in fetuses) stimulates erythropoiesis. In the central nervous system, neurons express EPO receptor (EPOR) and astrocytes produce EPO. EPO has been shown to protect primary cultured neurons from N-methyl-D-aspartate (NMDA) receptor-mediated glutamate toxicity. Here we report in vivo evidence that EPO protects neurons against ischemia-induced cell death. Infusion of EPO into the lateral ventricles of gerbils prevented ischemia-induced learning disability and rescued hippocampal CA1 neurons from lethal ischemic damage. The neuroprotective action of exogenous EPO was also confirmed by counting synapses in the hippocampal CA1 region. Infusion of soluble EPOR (an extracellular domain capable of binding with the ligand) into animals given a mild ischemic treatment that did not produce neuronal damage, caused neuronal degeneration and impaired learning ability, whereas infusion of the heat-denatured soluble EPOR was not detrimental, demonstrating that the endogenous brain EPO is crucial for neuronal survival. The presence of EPO in neuron cultures did not repress a NMDA receptor-mediated increase in intracellular Ca2+, but rescued the neurons from NO-induced death. Taken together EPO may exert its neuroprotective effect by reducing the NO-mediated formation of free radicals or antagonizing their toxicity.

Topics: Animals; Avoidance Learning; Cell Death; Cell Survival; Cells, Cultured; Cerebral Ventricles; Erythropoietin; Gerbillinae; Hippocampus; Humans; Infusions, Parenteral; Ischemic Attack, Transient; Male; Neurons; Nitric Oxide; Nitroprusside; Rats; Rats, Wistar; Receptors, Erythropoietin; Recombinant Proteins

Topics: Anemia; Animals; Erythropoiesis; Erythropoietin; Hemorrhage; Hypothalamus; Hypoxia, Brain; Ischemic Attack, Transient; Rats