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Query: UMLS:C0022116 (ischemia)
 91,303 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Erythropoietin (EPO), the principal hematopoietic cytokine produced by the kidney and the liver in fetuses, regulates mammalian erythropoiesis and exhibits diverse cellular effects in non-hematopoietic tissues. The introduction of recombinant human EPO (rhEPO) has marked a significant advance in the management of anemia associated with chronic renal failure. At the same time, experimental studies have unveiled its potential cardioprotective actions. As with other preconditioning agents, administration of exogenous rhEPO can confer myocardial protection against ischemia-reperfusion injury, in terms of reduction in cellular apoptosis and necrosis as well as improvement in myocardial functional recovery. The purpose of this study is to review current information regarding the various protocols used to investigate the effects of rhEPO administration as well as its cardioprotective properties. We also address the potential mechanisms underlying the protective effects of EPO. A better understanding of these mechanisms is essential for the development of clinical applications and the design of novel therapeutical strategies.
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PMID:Erythropoietin and myocardial protection: what's new? 1601 30

Erythropoietin (epo), initially recognized and used clinically to increase erythropoiesis, has been shown to have beneficial effects on various other tissues in the setting of hypoxia and ischemia. Epo has been shown to reduce apoptosis after myocardial infarction, but few studies have evaluated the long-term effects of epo treatment on left ventricular (LV) remodeling, cardiac function, and blood flow after healing of a permanent coronary artery occlusion. The aim of this study was to assess the effects of epo treatment on the healed heart 6 weeks after myocardial infarction. Anesthetized rats underwent coronary artery occlusion and were treated with erythropoietin (5000 units/kg/day, n=21) or saline (n=20) the day before surgery, the day of, then for 5 days. At 6 weeks LV ventriculography to assess LV volumes and ejection fractions and histologic assessment of infarct size and LV cavity and wall dimensions were performed. Overall epo had no effect on LV remodeling or cardiac function. There were no significant differences in infarct morphology, infarct size (44+/-3% of the LV circumference versus 39+/-3%), LV cavity area, scar thickness, LV systolic volume, or ejection fraction (44+/-3% versus 39+/-3%) between the epo and saline groups, respectively. However, for any given size of myocardial infarct, LV ejection fraction was significantly higher in erythropoietin hearts and LV systolic volumes lower. Thus, in our model, treatment with epo had no long-term beneficial effect on LV remodeling after myocardial infarction but may have exerted some positive effect on LV function.
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PMID:Administration of erythropoietin fails to improve long-term healing or cardiac function after myocardial infarction in the rat. 1604 33

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.
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PMID:Ischemic preconditioning is mediated by erythropoietin through PI-3 kinase signaling in an animal model of transient ischemic attack. 1630 46

Cell death induced by the combined insult of hypoxia-ischemia in neonatal rodents has been extensively investigated. Ischemia-only-induced cell death, however, has been much less characterized. Based on the notion that 1) ischemic stroke is a relatively common disorder in human neonates, and 2) developing cells are more susceptible to apoptosis, the present study examined whether typical apoptosis was induced by cerebral ischemia in a new neonatal rat model. Erythropoietin (EPO; Epoetin) was tested for its protective effect against ischemia-induced cell death. Postnatal day 7 rats were subjected to permanent occlusion of the middle cerebral artery branch supplying the right whisker-barrel cortex. Terminal deoxynucleotidyl transferase biotin-dUTP nick end-labeled-positive cells in the ischemic region were detectable 4 h after ischemia and reached a peak level 16 h later. The cell death was preceded by caspase activation and cytochrome c release. Cell body shrinkage was evident among damaged cells. Agarose gel electrophoresis showed DNA damage with a smear pattern as well as DNA laddering. Electron microscopy demonstrated apoptotic features such as cell shrinkage, chromatin condensation, and fragmentation; meanwhile, necrotic alterations coexisted in the cytoplasm. EPO treatment increased signal transducers and activators of transcription-5 and Bcl-2 levels, markedly attenuated apoptotic cell death, and reduced ischemic infarct in the cortex. It is suggested that focal ischemia in the developing brain causes cell death with prominent apoptotic features coexisting with some characteristics of necrosis. This is consistent with the concept of hybrid death described previously in cultures and adult or developing brain. EPO may be explored as a potential therapy for neonatal ischemic stroke.
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PMID:Cell death mechanism and protective effect of erythropoietin after focal ischemia in the whisker-barrel cortex of neonatal rats. 1635 10

Erythropoietin (EPO) is a hormone that is neuroprotective in models of neurodegenerative diseases. This study examined whether EPO can protect against neuronal death in the CA1 region of the rat hippocampus following global cerebral ischemia. Recombinant human EPO was infused into the intracerebral ventricle either before or after the induction of ischemia produced by using the four-vessel-occlusion model in rat. Hippocampal CA1 neuron damage was ameliorated by infusion of 50 U EPO. Administration of EPO was neuroprotective if given 20 hr before or 20 min after ischemia, but not 1 hr following ischemia. Coinjection of the phosphoinositide 3 kinase inhibitor LY294002 with EPO inhibited the protective effects of EPO. Treatment with EPO induced phosphorylation of both AKT and its substrate, glycogen synthase kinase-3beta, in the CA1 region. EPO also enhanced the CA1 level of brain-derived neurotrophic factor. Finally, we determined that ERK activation played minor roles in EPO-mediated neuroprotection. These studies demonstrate that a single injection of EPO ICV up to 20 min after global ischemia is an effective neuroprotective agent and suggest that EPO is a viable candidate for treating global ischemic brain injury.
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PMID:Erythropoietin protects CA1 neurons against global cerebral ischemia in rat: potential signaling mechanisms. 1651 66

Neonatal hypoxia-ischemia (HI) is a common cause of brain damage and subsequent behavioral deficits in premature/term infants. Rapid auditory processing deficits have been suggested to play a role in later language impairments in this population. We have previously shown auditory deficits in rats with neonatal HI injury and now report novel effects of behavioral sparing and neuroprotection following treatment with a low dose of Erythropoietin using this HI injury model.
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PMID:The effects of erythropoietin on auditory processing following neonatal hypoxic-ischemic injury. 1664 62

Erythropoietin (EPO) has been suggested to have a cardioprotective effect against ischemia. The purpose of this study was to examine the effects of EPO on cardiac remodeling after myocardial infarction (MI). MI was induced by ligation of the coronary artery in Wistar rats. The rats with MI were randomly divided into untreated MI and two EPO-treated MI groups. EPO was administered subcutaneously by injection once a day for 4 days after MI at 5000 U/kg or 3 times a week for 4 weeks at 1000 U/kg. Five days after MI, EPO prevented the increase in activated caspase 3, matrix metalloproteinase-2, and transcriptional activation of activator protein-1 in non-infarcted myocardium. Four weeks after MI, left ventricular weight, left ventricular end-diastolic pressure, and left ventricular dimension were increased, and ejection fraction and E wave deceleration time were decreased. EPO significantly attenuated this ventricular remodeling and systolic and diastolic dysfunction. In addition, EPO significantly attenuated the interstitial fibrosis and remodeling-related gene expression in non-infarcted myocardium. Furthermore, EPO significantly enhanced angiogenesis and reduced apoptotic cell death in peri-infarcted myocardium. In conclusion, when administered after MI, EPO prevents cardiac remodeling and improves ventricular function with enhanced angiogenesis and reduced apoptosis.
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PMID:Effects of erythropoietin on cardiac remodeling after myocardial infarction. 1671 99

Erythropoietin and its receptor, a cytokine hormone long-known for its pro-erythropoietic effect, has been found to be expressed on a variety of tissues, including the cardiovascular system. Recent experimental studies in the ischemia-reperfusion model have demonstrated that erythropoietin has a significant cardioprotective and pro-angiogenic effect. This effect is quantified by a reduction in the relative infarct and apoptosis area and improved recovery of mechanical function. Despite potentially detrimental effects, erythropoietin has been used extensively in the last decade for treatment of anemia associated with chronic renal failure, and it has been found to be a safe drug in humans. The potential role of erythropoietin in the treatment of ischemic heart disease in humans has yet to be demonstrated in preliminary clinical trials.
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PMID:[Erythropoietin as a protective agent in myocardial ischemia]. 1680 23

Erythropoietin (EPO) is a hypoxia-inducible hormone required for erythroid differentiation. Expression of the EPO receptor is not restricted to hematopoietic cells and exhibits a multi-tissue distribution that includes neural cells, vascular endothelium and muscle progenitor cells. The ability for EPO to stimulate progenitor cell proliferation and prevent apoptosis is critical for maintenance of the erythroid lineage, but is also observed in neural and muscle progenitor cells. Mice lacking the EPO receptor die in utero due to severe anemia. However, even prior to lack of erythroid cell production in the embryo proper, these mice exhibit increased apoptosis in the brain as early as E10.5 and a reduction in the number of neural progenitor cells. Corresponding cultures of primary neural cells exhibit decreased neuron generation and increased sensitivity to reduced oxygen tension, and neurons do not survive after 24 h at low oxygen tension. In contrast, hypoxia induces EPO and EPO receptor in wild-type neuronal cells, and EPO enhances neuron survival at low oxygen tension. In vivo EPO is neuroprotective in adult animal models for brain ischemia. Induction of EPO and its receptor by hypoxia likely contributes to its neuroprotective activity and selective cell survival in the brain during hypoxic stress.
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PMID:Erythropoietin and normal brain development: receptor expression determines multi-tissue response. 1690 40

Recently, erythropoietin was shown to have both hematopoietic as well as tissue-protective properties. Erythropoietin (EPO) had a protective effect in animal models of cerebral ischemia, mechanical trauma of the nervous system, myocardial infarction, and ischemia-reperfusion (I/R) injury of the kidney. It is not known whether EPO protects the liver against I/R injury. Using a rat model of liver I/R injury, we aimed to determine the effect of the administration of human recombinant erythropoietin (rhEPO) on liver injury. Rats were subjected to 30 min of liver ischemia followed by 2 h of reperfusion. When compared with the sham-operated rats, I/R resulted in significant rises in the serum levels of aspartate aminotransferase, alanine aminotransferase, lactate dehydrogenase, gamma-glutamyl transferase, tissue lipid peroxidation, caspase-3 activity and altered histology. Administration of rhEPO 5 min before ischemia was able to reduce the biochemical evidence of liver injury; however, this protection was not evident when rhEPO was administered 5 min before reperfusion. Mechanistically, early administration of rhEPO was able to reduce the oxidative stress and caspase-3 activation, suggesting the subsequent reduction of apoptosis. This study provides the first evidence that rhEPO causes a substantial reduction of the liver injury induced by I/R in the rat.
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PMID:Recombinant human erythropoietin protects the liver from hepatic ischemia-reperfusion injury in the rat. 1701 28


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