Journal Mobile Options
Table of Contents
Vol. 31, No. 5, 2009
Issue release date: September 2009
Free Access
Dev Neurosci 2009;31:403–411
(DOI:10.1159/000232558)

Erythropoietin Sustains Cognitive Function and Brain Volume after Neonatal Stroke

Gonzalez F.F.a · Abel R.d, e · Almli C.R.d–f · Mu D.b, g · Wendland M.c · Ferriero D.M.a, b
Departments of aPediatrics, bNeurology and cRadiology, University of California, San Francisco, Calif., dDepartmental Neuropsychobiology Laboratory, eProgram in Occupational Therapy, and fDepartment of Neurology, Washington University School of Medicine, St. Louis, Mo., USA; gDepartment of Pediatrics, West China Second Hospital, Sichuan University, Chengdu, China
email Corresponding Author

Abstract

Neonatal stroke leads to mortality and severe morbidity, but there currently is no effective treatment. Erythropoietin (EPO) promotes cytoprotection and neurogenesis in the short term following brain injury; however, long-term cognitive outcomes and optimal dosing regimens have not been clarified. We performed middle cerebral artery occlusion in postnatal day 10 rats, which were treated with either a single dose of EPO (5 U/g, i.p.) immediately upon reperfusion, or 3 doses of EPO (1 U/g, i.p. each) at 0 h, 24 h, and 7 days after injury. At 3 months after injury, rats treated with 3 doses of EPO did not differ from shams in the Morris water maze, and generally performed better than either rats treated with a single dose or vehicle-treated injured rats. These multiple-dose-treated rats also had increases in hemispheric volume and its subregions. These results suggest that additional, later doses of EPO may be required for cell repair, proliferation, and long-term incorporation into neural networks after neonatal brain injury.


 goto top of outline Key Words

  • Neonatal hypoxic-ischemic injury
  • Neonatal brain injury
  • Stroke
  • Cognitive function

 goto top of outline Abstract

Neonatal stroke leads to mortality and severe morbidity, but there currently is no effective treatment. Erythropoietin (EPO) promotes cytoprotection and neurogenesis in the short term following brain injury; however, long-term cognitive outcomes and optimal dosing regimens have not been clarified. We performed middle cerebral artery occlusion in postnatal day 10 rats, which were treated with either a single dose of EPO (5 U/g, i.p.) immediately upon reperfusion, or 3 doses of EPO (1 U/g, i.p. each) at 0 h, 24 h, and 7 days after injury. At 3 months after injury, rats treated with 3 doses of EPO did not differ from shams in the Morris water maze, and generally performed better than either rats treated with a single dose or vehicle-treated injured rats. These multiple-dose-treated rats also had increases in hemispheric volume and its subregions. These results suggest that additional, later doses of EPO may be required for cell repair, proliferation, and long-term incorporation into neural networks after neonatal brain injury.

Copyright © 2009 S. Karger AG, Basel


 goto top of outline References
  1. Lynch JK, Nelson KB: Epidemiology of perinatal stroke. Curr Opin Pediatr 2001;13:499–505.
  2. Lee J, Croen LA, Lindan C, Nash KB, Yoshida CK, Ferriero DM, Barkovich AJ, Wu YW: Predictors of outcome in perinatal arterial stroke: a population-based study. Ann Neurol 2005;58:303–308.
  3. McKinstry RC, Miller JH, Snyder AZ, Mathur A, Schefft GL, Almli CR, Shimony JS, Shiran SI, Neil JJ: A prospective, longitudinal diffusion tensor imaging study of brain injury in newborns. Neurology 2002;59:824–833.
  4. Villa P, Bigini P, Mennini T, Agnello D, Laragione T, Cagnotto A, Viviani B, Marinovich M, Cerami A, Coleman TR, Brines M, Ghezzi P: Erythropoietin selectively attenuates cytokine production and inflammation in cerebral ischemia by targeting neuronal apoptosis. J Exp Med 2003;198:971–975.
  5. Agnello D, Bigini P, Villa P, Mennini T, Cerami A, Brines ML, Ghezzi P: Erythropoietin exerts an anti-inflammatory effect on the CNS in a model of experimental autoimmune encephalomyelitis. Brain Res 2002;952:128–134.
  6. Arvin B, Neville LF, Barone FC, Feuerstein GZ: The role of inflammation and cytokines in brain injury. Neurosci Biobehav Rev 1996;20:445–452.
  7. Wang L, Zhang Z, Wang Y, Zhang R, Chopp M: Treatment of stroke with erythropoietin enhances neurogenesis and angiogenesis and improves neurological function in rats. Stroke 2004;35:1732–1737.
  8. Chong ZZ, Kang JQ, Maiese K: Angiogenesis and plasticity: role of erythropoietin in vascular systems. J Hematother Stem Cell Res 2002;11:863–871.
  9. Bernaudin M, Marti HH, Roussel S, Divoux D, Nouvelot A, MacKenzie ET, Petit E: A potential role for erythropoietin in focal permanent cerebral ischemia in mice. J Cereb Blood Flow Metab 1999;19:643–651.
  10. Mu D, Chang YS, Vexler ZS, Ferriero DM: Hypoxia-inducible factor 1alpha and erythropoietin upregulation with deferoxamine salvage after neonatal stroke. Exp Neurol 2005;195:407–415.
  11. Juul SE, Anderson DK, Li Y, Christensen RD: Erythropoietin and erythropoietin receptor in the developing human central nervous system. Pediatr Res 1998;43:40–49.
  12. Sadamoto Y, Igase K, Sakanaka M, Sato K, Otsuka H, Sakaki S, Masuda S, Sasaki R: Erythropoietin prevents place navigation disability and cortical infarction in rats with permanent occlusion of the middle cerebral artery. Biochem Biophys Res Commun 1998;253:26–32.
  13. Aydin A, Genc K, Akhisaroglu M, Yorukoglu K, Gokmen N, Gonullu E: Erythropoietin exerts neuroprotective effect in neonatal rat model of hypoxic-ischemic brain injury. Brain Dev 2003;25:494–498.
  14. Sola A, Wen TC, Hamrick SE, Ferriero DM: Potential for protection and repair following injury to the developing brain: a role for erythropoietin? Pediatr Res 2005;57:110R–117R.
  15. Sakanaka M, Wen TC, Matsuda S, Masuda S, Morishita E, Nagao M, Sasaki R: In vivo evidence that erythropoietin protects neurons from ischemic damage. Proc Natl Acad Sci USA 1998;95:4635–4640.
  16. Brines ML, Ghezzi P, Keenan S, Agnello D, de Lanerolle NC, Cerami C, Itri LM, Cerami A: Erythropoietin crosses the blood-brain barrier to protect against experimental brain injury. Proc Natl Acad Sci USA 2000;97:10526–10531.
  17. Kumral A, Ozer E, Yilmaz O, Akhisaroglu M, Gokmen N, Duman N, Ulukus C, Genc S, Ozkan H: Neuroprotective effect of erythropoietin on hypoxic-ischemic brain injury in neonatal rats. Biol Neonate 2003;83:224–228.
  18. Matsushita H, Johnston MV, Lange MS, Wilson MA: Protective effect of erythropoietin in neonatal hypoxic ischemia in mice. Neuroreport 2003;14:1757–1761.
  19. Sun Y, Zhou C, Polk P, Nanda A, Zhang JH: Mechanisms of erythropoietin-induced brain protection in neonatal hypoxia-ischemia rat model. J Cereb Blood Flow Metab 2004;24:259–270.
  20. Spandou E, Papoutsopoulou S, Soubasi V, Karkavelas G, Simeonidou C, Kremenopoulos G, Guiba-Tziampiri O: Hypoxia-ischemia affects erythropoietin and erythropoietin receptor expression pattern in the neonatal rat brain. Brain Res 2004;1021:167–172.
  21. Solaroglu I, Solaroglu A, Kaptanoglu E, Dede S, Haberal A, Beskonakli E, Kilinc K: Erythropoietin prevents ischemia-reperfusion from inducing oxidative damage in fetal rat brain. Childs Nerv Syst 2003;19:19–22.
  22. Kumral A, Uysal N, Tugyan K, Sonmez A, Yilmaz O, Gokmen N, Kiray M, Genc S, Duman N, Koroglu TF, Ozkan H, Genc K: Erythropoietin improves long-term spatial memory deficits and brain injury following neonatal hypoxia-ischemia in rats. Behav Brain Res 2004;153:77–86.
  23. Sola A, Rogido M, Lee BH, Genetta T, Wen TC: Erythropoietin after focal cerebral ischemia activates the Janus kinase-signal transducer and activator of transcription signaling pathway and improves brain injury in postnatal day 7 rats. Pediatr Res 2005;57:481–487.
  24. Chang YS, Mu D, Wendland M, Sheldon RA, Vexler ZS, McQuillen PS, Ferriero DM: Erythropoietin improves functional and histological outcome in neonatal stroke. Pediatr Res 2005;58:106–111.
  25. Derugin N, Wendland M, Muramatsu K, Roberts TP, Gregory G, Ferriero DM, Vexler ZS: Evolution of brain injury after transient middle cerebral artery occlusion in neonatal rats. Stroke 2000;31:1752–1761.
  26. Mu D, Jiang X, Sheldon RA, Fox CK, Hamrick SE, Vexler ZS, Ferriero DM: Regulation of hypoxia-inducible factor 1alpha and induction of vascular endothelial growth factor in a rat neonatal stroke model. Neurobiol Dis 2003;14:524–534.
  27. Hagberg H, Bona E, Gilland E, Puka-Sundvall M: Hypoxia-ischaemia model in the 7-day-old rat: possibilities and shortcomings. Acta Paediatr Suppl 1997;422:85–88.
  28. Regeur L, Pakkenberg B: Optimizing sampling designs for volume measurements of components of human brain using a stereological method. J Microsc 1989;155:113–121.
  29. Paxinos G, Watson C: The Rat Brain in Stereotaxic Coordinates. San Diego, Elsevier Academic Press, 2005.
  30. Gonzalez FF, McQuillen P, Mu D, Chang Y, Wendland M, Vexler Z, Ferriero DM: Erythropoietin enhances long-term neuroprotection and neurogenesis in neonatal stroke. Dev Neurosci 2007;29:321–330.
  31. Digicaylioglu M, Lipton SA: Erythropoietin-mediated neuroprotection involves cross-talk between Jak2 and NF-kappaB signalling cascades. Nature 2001;412:641–647.
  32. Wen TC, Sadamoto Y, Tanaka J, Zhu PX, Nakata K, Ma YJ, Hata R, Sakanaka M: Erythropoietin protects neurons against chemical hypoxia and cerebral ischemic injury by up-regulating bcl-xl expression. J Neurosci Res 2002;67:795–803.
  33. Shingo T, Sorokan ST, Shimazaki T, Weiss S: Erythropoietin regulates the in vitro and in vivo production of neuronal progenitors by mammalian forebrain neural stem cells. J Neurosci 2001;21:9733–9743.
  34. Zhang F, Wang S, Cao G, Gao Y, Chen J: Signal transducers and activators of transcription 5 contributes to erythropoietin-mediated neuroprotection against hippocampal neuronal death after transient global cerebral ischemia. Neurobiol Dis 2007;25:45–53.
  35. Yin D, Kawabata H, Tcherniamtchouk O, Huynh T, Black KL, Koeffler HP: Glioblastoma multiforme cells: expression of erythropoietin receptor and response to erythropoietin. Int J Oncol 2007;31:1193–1198.
  36. Lee ST, Chu K, Sinn DI, Jung KH, Kim EH, Kim SJ, Kim JM, Ko SY, Kim M, Roh JK: Erythropoietin reduces perihematomal inflammation and cell death with eNOS and STAT3 activations in experimental intracerebral hemorrhage. J Neurochem 2006;96:1728–1739.
  37. Park MH, Lee SM, Lee JW, Son DJ, Moon DC, Yoon DY, Hong JT: Erk-mediated production of neurotrophic factors by astrocytes promotes neuronal stem cell differentiation by erythropoietin. Biochem Biophys Res Commun 2006;339:1021–1028.
  38. Kilic U, Kilic E, Soliz J, Bassetti CI, Gassmann M, Hermann DM: Erythropoietin protects from axotomy-induced degeneration of retinal ganglion cells by activating ERK-1/-2. FASEB J 2005;19:249–251.
  39. Zachary I: Neuroprotective role of vascular endothelial growth factor: signalling mechanisms, biological function, and therapeutic potential. Neurosignals 2005;14:207–221.
  40. Wang L, Zhang ZG, Zhang RL, Gregg SR, Hozeska-Solgot A, LeTourneau Y, Wang Y, Chopp M: Matrix metalloproteinase 2 (MMP2) and MMP9 secreted by erythropoietin-activated endothelial cells promote neural progenitor cell migration. J Neurosci 2006;26:5996–6003.
  41. Urao N, Okigaki M, Yamada H, Aadachi Y, Matsuno K, Matsui A, Matsunaga S, Tateishi K, Nomura T, Takahashi T, Tatsumi T, Matsubara H: Erythropoietin-mobilized endothelial progenitors enhance reendothelialization via Akt-endothelial nitric oxide synthase activation and prevent neointimal hyperplasia. Circ Res 2006;98:1405–1413.
  42. van Praag H, Kempermann G, Gage FH: Neural consequences of environmental enrichment. Nat Rev Neurosci 2000;1:191–198.
  43. Lambert TJ, Fernandez SM, Frick KM: Different types of environmental enrichment have discrepant effects on spatial memory and synaptophysin levels in female mice. Neurobiol Learn Mem 2005;83:206–216.
  44. Bennett JC, McRae PA, Levy LJ, Frick KM: Long-term continuous, but not daily, environmental enrichment reduces spatial memory decline in aged male mice. Neurobiol Learn Mem 2006;85:139–152.
  45. Fan Y, Liu Z, Weinstein PR, Fike JR, Liu J: Environmental enrichment enhances neurogenesis and improves functional outcome after cranial irradiation. Eur J Neurosci 2007;25:38–46.
  46. Segovia G, Del Arco A, de Blas M, Garrido P, Mora F: Effects of an enriched environment on the release of dopamine in the prefrontal cortex produced by stress and on working memory during aging in the awake rat. Behav Brain Res 2008;187:304–311.
  47. Gobbo OL, O’Mara SM: Impact of enriched-environment housing on brain-derived neurotrophic factor and on cognitive performance after a transient global ischemia. Behav Brain Res 2004;152:231–241.
  48. Chen X, Li Y, Kline AE, Dixon CE, Zafonte RD, Wagner AK: Gender and environmental effects on regional brain-derived neurotrophic factor expression after experimental traumatic brain injury. Neuroscience 2005;135:11–17.
  49. Pereira LO, Arteni NS, Petersen RC, da Rocha AP, Achaval M, Netto CA: Effects of daily environmental enrichment on memory deficits and brain injury following neonatal hypoxia-ischemia in the rat. Neurobiol Learn Mem 2007;87:101–108.
  50. Dahlqvist P, Ronnback A, Bergstrom SA, Soderstrom I, Olsson T: Environmental enrichment reverses learning impairment in the Morris water maze after focal cerebral ischemia in rats. Eur J Neurosci 2004;19:2288–2298.
  51. Pereira LO, Strapasson AC, Nabinger PM, Achaval M, Netto CA: Early enriched housing results in partial recovery of memory deficits in female, but not in male, rats after neonatal hypoxia-ischemia. Brain Res 2008;1218:257–266.
  52. Llorens-Martin MV, Rueda N, Martinez-Cue C, Torres-Aleman I, Florez J, Trejo JL: Both increases in immature dentate neuron number and decreases of immobility time in the forced swim test occurred in parallel after environmental enrichment of mice. Neuroscience 2007;147:631–638.
  53. Steiner B, Zurborg S, Horster H, Fabel K, Kempermann G: Differential 24 h responsiveness of Prox1-expressing precursor cells in adult hippocampal neurogenesis to physical activity, environmental enrichment, and kainic acid-induced seizures. Neuroscience 2008;154:521–529.
  54. Altemus KL, Almli CR: Neonatal hippocampal damage in rats: long-term spatial memory deficits and associations with magnitude of hippocampal damage. Hippocampus 1997;7:403–415.
  55. Almli CR, Levy TJ, Han BH, Shah AR, Gidday JM, Holtzman DM: BDNF protects against spatial memory deficits following neonatal hypoxia-ischemia. Exp Neurol 2000;166:99–114.
  56. Pistell PJ, Nelson CM, Miller MG, Spangler EL, Ingram DK, Devan BD: Striatal lesions interfere with acquisition of a complex maze task in rats. Behav Brain Res 2008.
  57. Kellert BA, McPherson RJ, Juul SE: A comparison of high-dose recombinant erythropoietin treatment regimens in brain-injured neonatal rats. Pediatr Res 2007;61:451–455.

 goto top of outline Author Contacts

Fernando F. Gonzalez, MD
Neonatal Brain Disorders Laboratory, University of California, San Francisco
521 Parnassus Avenue, C215
San Francisco, CA 94143-0663 (USA)
Tel. +1 415 502 5822, Fax +1 415 502 5821, E-Mail gonzalezf@peds.ucsf.edu


 goto top of outline Article Information

Received: October 2, 2008
Accepted: December 20, 2008
Published online: August 11, 2009
Number of Print Pages : 9
Number of Figures : 4, Number of Tables : 1, Number of References : 57


 goto top of outline Publication Details

Developmental Neuroscience

Vol. 31, No. 5, Year 2009 (Cover Date: September 2009)

Journal Editor: Levison S.W. (Newark, N.J.)
ISSN: 0378-5866 (Print), eISSN: 1421-9859 (Online)

For additional information: http://www.karger.com/DNE


Copyright / Drug Dosage / Disclaimer

Copyright: All rights reserved. No part of this publication may be translated into other languages, reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying, recording, microcopying, or by any information storage and retrieval system, without permission in writing from the publisher or, in the case of photocopying, direct payment of a specified fee to the Copyright Clearance Center.
Drug Dosage: The authors and the publisher have exerted every effort to ensure that drug selection and dosage set forth in this text are in accord with current recommendations and practice at the time of publication. However, in view of ongoing research, changes in goverment regulations, and the constant flow of information relating to drug therapy and drug reactions, the reader is urged to check the package insert for each drug for any changes in indications and dosage and for added warnings and precautions. This is particularly important when the recommended agent is a new and/or infrequently employed drug.
Disclaimer: The statements, opinions and data contained in this publication are solely those of the individual authors and contributors and not of the publishers and the editor(s). The appearance of advertisements or/and product references in the publication is not a warranty, endorsement, or approval of the products or services advertised or of their effectiveness, quality or safety. The publisher and the editor(s) disclaim responsibility for any injury to persons or property resulting from any ideas, methods, instructions or products referred to in the content or advertisements.

Abstract

Neonatal stroke leads to mortality and severe morbidity, but there currently is no effective treatment. Erythropoietin (EPO) promotes cytoprotection and neurogenesis in the short term following brain injury; however, long-term cognitive outcomes and optimal dosing regimens have not been clarified. We performed middle cerebral artery occlusion in postnatal day 10 rats, which were treated with either a single dose of EPO (5 U/g, i.p.) immediately upon reperfusion, or 3 doses of EPO (1 U/g, i.p. each) at 0 h, 24 h, and 7 days after injury. At 3 months after injury, rats treated with 3 doses of EPO did not differ from shams in the Morris water maze, and generally performed better than either rats treated with a single dose or vehicle-treated injured rats. These multiple-dose-treated rats also had increases in hemispheric volume and its subregions. These results suggest that additional, later doses of EPO may be required for cell repair, proliferation, and long-term incorporation into neural networks after neonatal brain injury.



 goto top of outline Author Contacts

Fernando F. Gonzalez, MD
Neonatal Brain Disorders Laboratory, University of California, San Francisco
521 Parnassus Avenue, C215
San Francisco, CA 94143-0663 (USA)
Tel. +1 415 502 5822, Fax +1 415 502 5821, E-Mail gonzalezf@peds.ucsf.edu


 goto top of outline Article Information

Received: October 2, 2008
Accepted: December 20, 2008
Published online: August 11, 2009
Number of Print Pages : 9
Number of Figures : 4, Number of Tables : 1, Number of References : 57


 goto top of outline Publication Details

Developmental Neuroscience

Vol. 31, No. 5, Year 2009 (Cover Date: September 2009)

Journal Editor: Levison S.W. (Newark, N.J.)
ISSN: 0378-5866 (Print), eISSN: 1421-9859 (Online)

For additional information: http://www.karger.com/DNE


Copyright / Drug Dosage

Copyright: All rights reserved. No part of this publication may be translated into other languages, reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying, recording, microcopying, or by any information storage and retrieval system, without permission in writing from the publisher or, in the case of photocopying, direct payment of a specified fee to the Copyright Clearance Center.
Drug Dosage: The authors and the publisher have exerted every effort to ensure that drug selection and dosage set forth in this text are in accord with current recommendations and practice at the time of publication. However, in view of ongoing research, changes in goverment regulations, and the constant flow of information relating to drug therapy and drug reactions, the reader is urged to check the package insert for each drug for any changes in indications and dosage and for added warnings and precautions. This is particularly important when the recommended agent is a new and/or infrequently employed drug.
Disclaimer: The statements, opinions and data contained in this publication are solely those of the individual authors and contributors and not of the publishers and the editor(s). The appearance of advertisements or/and product references in the publication is not a warranty, endorsement, or approval of the products or services advertised or of their effectiveness, quality or safety. The publisher and the editor(s) disclaim responsibility for any injury to persons or property resulting from any ideas, methods, instructions or products referred to in the content or advertisements.

References

  1. Lynch JK, Nelson KB: Epidemiology of perinatal stroke. Curr Opin Pediatr 2001;13:499–505.
  2. Lee J, Croen LA, Lindan C, Nash KB, Yoshida CK, Ferriero DM, Barkovich AJ, Wu YW: Predictors of outcome in perinatal arterial stroke: a population-based study. Ann Neurol 2005;58:303–308.
  3. McKinstry RC, Miller JH, Snyder AZ, Mathur A, Schefft GL, Almli CR, Shimony JS, Shiran SI, Neil JJ: A prospective, longitudinal diffusion tensor imaging study of brain injury in newborns. Neurology 2002;59:824–833.
  4. Villa P, Bigini P, Mennini T, Agnello D, Laragione T, Cagnotto A, Viviani B, Marinovich M, Cerami A, Coleman TR, Brines M, Ghezzi P: Erythropoietin selectively attenuates cytokine production and inflammation in cerebral ischemia by targeting neuronal apoptosis. J Exp Med 2003;198:971–975.
  5. Agnello D, Bigini P, Villa P, Mennini T, Cerami A, Brines ML, Ghezzi P: Erythropoietin exerts an anti-inflammatory effect on the CNS in a model of experimental autoimmune encephalomyelitis. Brain Res 2002;952:128–134.
  6. Arvin B, Neville LF, Barone FC, Feuerstein GZ: The role of inflammation and cytokines in brain injury. Neurosci Biobehav Rev 1996;20:445–452.
  7. Wang L, Zhang Z, Wang Y, Zhang R, Chopp M: Treatment of stroke with erythropoietin enhances neurogenesis and angiogenesis and improves neurological function in rats. Stroke 2004;35:1732–1737.
  8. Chong ZZ, Kang JQ, Maiese K: Angiogenesis and plasticity: role of erythropoietin in vascular systems. J Hematother Stem Cell Res 2002;11:863–871.
  9. Bernaudin M, Marti HH, Roussel S, Divoux D, Nouvelot A, MacKenzie ET, Petit E: A potential role for erythropoietin in focal permanent cerebral ischemia in mice. J Cereb Blood Flow Metab 1999;19:643–651.
  10. Mu D, Chang YS, Vexler ZS, Ferriero DM: Hypoxia-inducible factor 1alpha and erythropoietin upregulation with deferoxamine salvage after neonatal stroke. Exp Neurol 2005;195:407–415.
  11. Juul SE, Anderson DK, Li Y, Christensen RD: Erythropoietin and erythropoietin receptor in the developing human central nervous system. Pediatr Res 1998;43:40–49.
  12. Sadamoto Y, Igase K, Sakanaka M, Sato K, Otsuka H, Sakaki S, Masuda S, Sasaki R: Erythropoietin prevents place navigation disability and cortical infarction in rats with permanent occlusion of the middle cerebral artery. Biochem Biophys Res Commun 1998;253:26–32.
  13. Aydin A, Genc K, Akhisaroglu M, Yorukoglu K, Gokmen N, Gonullu E: Erythropoietin exerts neuroprotective effect in neonatal rat model of hypoxic-ischemic brain injury. Brain Dev 2003;25:494–498.
  14. Sola A, Wen TC, Hamrick SE, Ferriero DM: Potential for protection and repair following injury to the developing brain: a role for erythropoietin? Pediatr Res 2005;57:110R–117R.
  15. Sakanaka M, Wen TC, Matsuda S, Masuda S, Morishita E, Nagao M, Sasaki R: In vivo evidence that erythropoietin protects neurons from ischemic damage. Proc Natl Acad Sci USA 1998;95:4635–4640.
  16. Brines ML, Ghezzi P, Keenan S, Agnello D, de Lanerolle NC, Cerami C, Itri LM, Cerami A: Erythropoietin crosses the blood-brain barrier to protect against experimental brain injury. Proc Natl Acad Sci USA 2000;97:10526–10531.
  17. Kumral A, Ozer E, Yilmaz O, Akhisaroglu M, Gokmen N, Duman N, Ulukus C, Genc S, Ozkan H: Neuroprotective effect of erythropoietin on hypoxic-ischemic brain injury in neonatal rats. Biol Neonate 2003;83:224–228.
  18. Matsushita H, Johnston MV, Lange MS, Wilson MA: Protective effect of erythropoietin in neonatal hypoxic ischemia in mice. Neuroreport 2003;14:1757–1761.
  19. Sun Y, Zhou C, Polk P, Nanda A, Zhang JH: Mechanisms of erythropoietin-induced brain protection in neonatal hypoxia-ischemia rat model. J Cereb Blood Flow Metab 2004;24:259–270.
  20. Spandou E, Papoutsopoulou S, Soubasi V, Karkavelas G, Simeonidou C, Kremenopoulos G, Guiba-Tziampiri O: Hypoxia-ischemia affects erythropoietin and erythropoietin receptor expression pattern in the neonatal rat brain. Brain Res 2004;1021:167–172.
  21. Solaroglu I, Solaroglu A, Kaptanoglu E, Dede S, Haberal A, Beskonakli E, Kilinc K: Erythropoietin prevents ischemia-reperfusion from inducing oxidative damage in fetal rat brain. Childs Nerv Syst 2003;19:19–22.
  22. Kumral A, Uysal N, Tugyan K, Sonmez A, Yilmaz O, Gokmen N, Kiray M, Genc S, Duman N, Koroglu TF, Ozkan H, Genc K: Erythropoietin improves long-term spatial memory deficits and brain injury following neonatal hypoxia-ischemia in rats. Behav Brain Res 2004;153:77–86.
  23. Sola A, Rogido M, Lee BH, Genetta T, Wen TC: Erythropoietin after focal cerebral ischemia activates the Janus kinase-signal transducer and activator of transcription signaling pathway and improves brain injury in postnatal day 7 rats. Pediatr Res 2005;57:481–487.
  24. Chang YS, Mu D, Wendland M, Sheldon RA, Vexler ZS, McQuillen PS, Ferriero DM: Erythropoietin improves functional and histological outcome in neonatal stroke. Pediatr Res 2005;58:106–111.
  25. Derugin N, Wendland M, Muramatsu K, Roberts TP, Gregory G, Ferriero DM, Vexler ZS: Evolution of brain injury after transient middle cerebral artery occlusion in neonatal rats. Stroke 2000;31:1752–1761.
  26. Mu D, Jiang X, Sheldon RA, Fox CK, Hamrick SE, Vexler ZS, Ferriero DM: Regulation of hypoxia-inducible factor 1alpha and induction of vascular endothelial growth factor in a rat neonatal stroke model. Neurobiol Dis 2003;14:524–534.
  27. Hagberg H, Bona E, Gilland E, Puka-Sundvall M: Hypoxia-ischaemia model in the 7-day-old rat: possibilities and shortcomings. Acta Paediatr Suppl 1997;422:85–88.
  28. Regeur L, Pakkenberg B: Optimizing sampling designs for volume measurements of components of human brain using a stereological method. J Microsc 1989;155:113–121.
  29. Paxinos G, Watson C: The Rat Brain in Stereotaxic Coordinates. San Diego, Elsevier Academic Press, 2005.
  30. Gonzalez FF, McQuillen P, Mu D, Chang Y, Wendland M, Vexler Z, Ferriero DM: Erythropoietin enhances long-term neuroprotection and neurogenesis in neonatal stroke. Dev Neurosci 2007;29:321–330.
  31. Digicaylioglu M, Lipton SA: Erythropoietin-mediated neuroprotection involves cross-talk between Jak2 and NF-kappaB signalling cascades. Nature 2001;412:641–647.
  32. Wen TC, Sadamoto Y, Tanaka J, Zhu PX, Nakata K, Ma YJ, Hata R, Sakanaka M: Erythropoietin protects neurons against chemical hypoxia and cerebral ischemic injury by up-regulating bcl-xl expression. J Neurosci Res 2002;67:795–803.
  33. Shingo T, Sorokan ST, Shimazaki T, Weiss S: Erythropoietin regulates the in vitro and in vivo production of neuronal progenitors by mammalian forebrain neural stem cells. J Neurosci 2001;21:9733–9743.
  34. Zhang F, Wang S, Cao G, Gao Y, Chen J: Signal transducers and activators of transcription 5 contributes to erythropoietin-mediated neuroprotection against hippocampal neuronal death after transient global cerebral ischemia. Neurobiol Dis 2007;25:45–53.
  35. Yin D, Kawabata H, Tcherniamtchouk O, Huynh T, Black KL, Koeffler HP: Glioblastoma multiforme cells: expression of erythropoietin receptor and response to erythropoietin. Int J Oncol 2007;31:1193–1198.
  36. Lee ST, Chu K, Sinn DI, Jung KH, Kim EH, Kim SJ, Kim JM, Ko SY, Kim M, Roh JK: Erythropoietin reduces perihematomal inflammation and cell death with eNOS and STAT3 activations in experimental intracerebral hemorrhage. J Neurochem 2006;96:1728–1739.
  37. Park MH, Lee SM, Lee JW, Son DJ, Moon DC, Yoon DY, Hong JT: Erk-mediated production of neurotrophic factors by astrocytes promotes neuronal stem cell differentiation by erythropoietin. Biochem Biophys Res Commun 2006;339:1021–1028.
  38. Kilic U, Kilic E, Soliz J, Bassetti CI, Gassmann M, Hermann DM: Erythropoietin protects from axotomy-induced degeneration of retinal ganglion cells by activating ERK-1/-2. FASEB J 2005;19:249–251.
  39. Zachary I: Neuroprotective role of vascular endothelial growth factor: signalling mechanisms, biological function, and therapeutic potential. Neurosignals 2005;14:207–221.
  40. Wang L, Zhang ZG, Zhang RL, Gregg SR, Hozeska-Solgot A, LeTourneau Y, Wang Y, Chopp M: Matrix metalloproteinase 2 (MMP2) and MMP9 secreted by erythropoietin-activated endothelial cells promote neural progenitor cell migration. J Neurosci 2006;26:5996–6003.
  41. Urao N, Okigaki M, Yamada H, Aadachi Y, Matsuno K, Matsui A, Matsunaga S, Tateishi K, Nomura T, Takahashi T, Tatsumi T, Matsubara H: Erythropoietin-mobilized endothelial progenitors enhance reendothelialization via Akt-endothelial nitric oxide synthase activation and prevent neointimal hyperplasia. Circ Res 2006;98:1405–1413.
  42. van Praag H, Kempermann G, Gage FH: Neural consequences of environmental enrichment. Nat Rev Neurosci 2000;1:191–198.
  43. Lambert TJ, Fernandez SM, Frick KM: Different types of environmental enrichment have discrepant effects on spatial memory and synaptophysin levels in female mice. Neurobiol Learn Mem 2005;83:206–216.
  44. Bennett JC, McRae PA, Levy LJ, Frick KM: Long-term continuous, but not daily, environmental enrichment reduces spatial memory decline in aged male mice. Neurobiol Learn Mem 2006;85:139–152.
  45. Fan Y, Liu Z, Weinstein PR, Fike JR, Liu J: Environmental enrichment enhances neurogenesis and improves functional outcome after cranial irradiation. Eur J Neurosci 2007;25:38–46.
  46. Segovia G, Del Arco A, de Blas M, Garrido P, Mora F: Effects of an enriched environment on the release of dopamine in the prefrontal cortex produced by stress and on working memory during aging in the awake rat. Behav Brain Res 2008;187:304–311.
  47. Gobbo OL, O’Mara SM: Impact of enriched-environment housing on brain-derived neurotrophic factor and on cognitive performance after a transient global ischemia. Behav Brain Res 2004;152:231–241.
  48. Chen X, Li Y, Kline AE, Dixon CE, Zafonte RD, Wagner AK: Gender and environmental effects on regional brain-derived neurotrophic factor expression after experimental traumatic brain injury. Neuroscience 2005;135:11–17.
  49. Pereira LO, Arteni NS, Petersen RC, da Rocha AP, Achaval M, Netto CA: Effects of daily environmental enrichment on memory deficits and brain injury following neonatal hypoxia-ischemia in the rat. Neurobiol Learn Mem 2007;87:101–108.
  50. Dahlqvist P, Ronnback A, Bergstrom SA, Soderstrom I, Olsson T: Environmental enrichment reverses learning impairment in the Morris water maze after focal cerebral ischemia in rats. Eur J Neurosci 2004;19:2288–2298.
  51. Pereira LO, Strapasson AC, Nabinger PM, Achaval M, Netto CA: Early enriched housing results in partial recovery of memory deficits in female, but not in male, rats after neonatal hypoxia-ischemia. Brain Res 2008;1218:257–266.
  52. Llorens-Martin MV, Rueda N, Martinez-Cue C, Torres-Aleman I, Florez J, Trejo JL: Both increases in immature dentate neuron number and decreases of immobility time in the forced swim test occurred in parallel after environmental enrichment of mice. Neuroscience 2007;147:631–638.
  53. Steiner B, Zurborg S, Horster H, Fabel K, Kempermann G: Differential 24 h responsiveness of Prox1-expressing precursor cells in adult hippocampal neurogenesis to physical activity, environmental enrichment, and kainic acid-induced seizures. Neuroscience 2008;154:521–529.
  54. Altemus KL, Almli CR: Neonatal hippocampal damage in rats: long-term spatial memory deficits and associations with magnitude of hippocampal damage. Hippocampus 1997;7:403–415.
  55. Almli CR, Levy TJ, Han BH, Shah AR, Gidday JM, Holtzman DM: BDNF protects against spatial memory deficits following neonatal hypoxia-ischemia. Exp Neurol 2000;166:99–114.
  56. Pistell PJ, Nelson CM, Miller MG, Spangler EL, Ingram DK, Devan BD: Striatal lesions interfere with acquisition of a complex maze task in rats. Behav Brain Res 2008.
  57. Kellert BA, McPherson RJ, Juul SE: A comparison of high-dose recombinant erythropoietin treatment regimens in brain-injured neonatal rats. Pediatr Res 2007;61:451–455.