Export file:


  • RIS(for EndNote,Reference Manager,ProCite)
  • BibTex
  • Text


  • Citation Only
  • Citation and Abstract

Dexamethasone enhances glutamine synthetase activity and reduces N-methyl-D-aspartate neurotoxicity in mixed cultures of neurons and astrocytes

INSERM U 919, UMR CNRS 6232, Centre Cyceron, BP 5229, 14074 Caen Cedex, France

Special Issues: Molecular Mechanisms of Neurodegenerative Diseases

Astrocytes are claimed to protect neurons against excitotoxicity by clearing glutamate from the extracellular space and rapidly converting it into glutamine. Glutamine, is then released into the extracellular medium, taken up by neurons and transformed back into glutamate which is then stored into synaptic vesicles. Glutamine synthetase (GS), the key enzyme that governs this glutamate/glutamine cycle, is known to be upregulated by glucocorticoids. In the present work we have thus studied in parallel the effects of dexamethasone on glutamine synthetase activity and NMDA-induced neuronal death in cultures derived from the brain cortex of murine embryos. We showed that dexamethasone was able to markedly enhance GS activity in cultures of astrocytes but not in near pure neuronal cultures. The pharmacological characteristics of the dexamethasone action strongly suggest that it corresponds to a typical receptor-mediated effect. We also observed that long lasting incubation (72 h) of mixed astrocyte-neuron cultures in the presence of 100 nM dexamethasone significantly reduced the toxicity of NMDA treatment. Furthermore we demonstrated that methionine sulfoximine, a selective inhibitor of GS, abolished the dexamethasone-induced increase in GS activity and also markedly potentiated NMDA toxicity. Altogether these results suggest that dexamethasone may promote neuroprotection through a stimulation of astrocyte glutamine synthetase.
  Article Metrics


1. Scully JL, Otten U (1995) Glucocorticoids, neurotrophins and neurodegeneration. J Steroid Mol Biol 52: 391-401.    

2. Reagan LP, Mc Ewen BS (1997) Controversies surrounding glucocorticoid-mediated cell death in the hippocampus. J Chem Neuroanat 13: 149-167.    

3. De Kloet ER, Oitzl MS, Joëls M (1999) Stress and cognition: are corticosteroids good or bad guys. Trends Neurosci 22: 422-426.    

4. Abraham IM, Harkany T, Horvath KM, et al. (2001) Action of glucocorticoids on survival of nerve cells: promoting neurodegeneration or neuroprotection? J Neuroendocrinol 13: 749-760.

5. Sapolsky RM, Pulsinelli WA (1985) Glucocorticoids potentiate ischemic injury to neurons: therapeutic implications. Science 229: 1397-1400.    

6. Adachi N, Cheng J, Liu K, et al. (1998) Dexamethasone aggravates ischemic-induced neuronal damage by facilitating the onset of anoxic depolarisation and the increase in the intracellular Ca++ concentration in gerbil hippocampus. J Cereb Blood Flow Metab 18: 274-280.

7. Semba J, Miyoshi R, Kito S (1996) Nicotine protects against the dexamethasone potentiation of kainic acid- induced neurotoxicity in cultured hippocampal neurons. Brain Res 753: 335-338.

8. Mc Intosh LJ, Sapolsky RM (1996) Glucocorticoids increase the accumulation of reactive oxygen species and enhance adriamycin-induced toxicity in neuronal culture. Exptl Neurol 141: 201-2016.    

9. Mutsaers HA, Tofighi R (2012) Dexamethasone enhances oxidative stress-induced cell death in murine neural stem cells. Neurotox Res 22: 127-137.    

10. Goodman Y, Bruce A, Cheng B, et al. (1996) Estrogens attenuate and corticosterone exacerbates excitotoxicity, oxidative injury and amyloid beta-peptide toxicity in hippocampal neurons. J Neurochem 66: 1836-1844.

11. Brooke S, Howard S, Sapolsky R (1998) Energy dependency of glucocorticoid exacerbation of gp120 neurotoxicity. J Neurochem 71: 1187-1193.

12. Noguchi KK, Walls KC, Wozniak DF, et al. (2008) Acute neonatal glucocorticoid exposure produces selective and rapid cerebellar neural progenitors cell apoptotic death. Cell Death Differ 15: 1582-1592.    

13. Sloviter RL, Valiquette G, Abrams GM, et al. (1989) Selective loss of hippocampal granule cells in the mature rat brain after adrenalectomy. Science 243: 535- 538.    

14. Gould E, Tanapat P, Cameron HA (1997) Adrenal steroids suppress granule cell death in the developping dentate gyrus through an NMDA receptor-dependent mechanism. Brain Res Dev 103: 91-93.    

15. Huang J, Strafaci JA, Azmitia EC (1997) 5HT1A receptor agonists reverse adrenalectomy-induced loss of granule neuronal morphology in the rat dentate gyrus. Neurochem Res 22: 1329-1337.    

16. Unlap T, Jope RS (1995) Inhibition of NF-kB DNA binding activity by glucocorticoids in rat brain. Neurosci Lett 198: 41-44.    

17. Macaya A, Munell F, Ferrer I, et al. (1998) Cell death and associated c-jun induction in perinatal hypoxia-ischemia: effect of the neuroprotective drug dexamethasone. Mol Brain Res 56: 29-37.    

18. Bertorelli R, Adami M, di Santo E, et al. (1998) MK 801 and dexamethasone reduce both Tumor Necrosis Factor levels and infarct volume after focal ischemia in the rat brain. Neurosci Lett 246: 41-44.    

19. Funder JW (1994) Corticoid receptors and the central nervous system. J Steroid Biochem Mol Biol 49:381-384.    

20. Kawata M, Yuri K, Ozawa H, et al. (1998) Steroid hormones and their receptors in the brain. J Steroid Biochem Mol Biol 65: 273-280.    

21. de Kloet ER, Vreugdenhil E, Oitzl MS, et al. (1998) Brain corticosteroid balance in health and disease. Endocrine Rev 19: 269-301.

22. Mc Leod MR, Johansson IM, Söderström I, et al. (2003) Mineralocorticoid receptor expression and increased survival following neuronal injury. Europ J Neurosci 17: 1549-1555.    

23. Montaron M, Piazza P, Aurousseau C, et al. (2003) Implication of corticosteroid receptors in the regulation of hippocampal structural plasticity. Eur J Neurosci 18: 3105-3111.    

24. Virgin CE, Ha TP, Packen DR, et al. (1991) Glucocorticoids inhibit glucose transport and glutamate uptake in hippocampal astrocytes: implications for glucocorticoid neurotoxicity. J Neurochem 57:1422-1428.    

25. Wang S, Lim G, Zeng Q, et al. (2005) Central glucocorticoid receptors modulate the expression and function of spinal NMDA receptors after peripheral nerve injury. J Neurosci 25: 488-495.    

26. Mangat HS, Islam A, Heigensköld C, et al. (1998) Long-term adrenalectomy decreases NMDA receptors in rat hippocampus. Neuroreport 9: 2011-2014.    

27. Relton JK, Strijbos PJML, O'Shaughnessy CT, et al. (1991) Lipocortin-1 is an endogenous inhibitor of ischemic damage in the cat brain. J Exptl Med 174: 305-310.    

28. Yamagata K, Andreason K, Kaufmann WE, et al. (1993) Expression of a mitogen-inducible cyclo-oxygenase in brain neurons: regulation by synaptic activity and glucocorticoids. Neuron 11:371-86.    

29. Weber CM, Eke BC, Maines MD (1994) Corticosterone regulates heme oxygenase-2 and NO synthase transcription and protein expression in rat brain. J Neurochem 63: 953-962.

30. Gorovitz R, Avidan N, Avisar N, et al. (1997) Glutamine synthetase protects against neuronal degeneration in injured retinal tissue. Proc Natl Acad Sci U S A 94: 7024-7029.    

31. Almeida OFX, Condé GL, Crochemore C, et al. (2000) Subtle shifts in the ratio between pro and antiapoptotic molecules after the activation of corticosteroid receptors decide neuronal fate. FASEB J 14:779-790.

32. Golde S, Coles A, Lindquist J, et al. (2003) Decreased iNOS synthesis mediates dexamethasone-induced protection of neurons from inflammatory injury in vitro. Europ J Neurosci 18: 2527-2537.    

33. Bertorelli R, Adami M, Di Santo E, et al. (1998) MK801 and dexamethasone reduce both tumor necrosis factor levels and infarct volume after focal cerebral ischemai in the rat brain. Neurosci Lett 246: 41-44.    

34. Felszeghy K, Banisadr G, Rostène W, et al. (2004) Dexamethasone downregulates chemokine receptor CXCR4 and exerts neuroprotection against hypoxia/ischemia-induced brain injury in neonatal rats. Neuro Immunomodul 11: 404-413.

35. Chen YZ, Qiu J (1999) Pleiotropic signaling pathways in rapid, non genomic, actions of glucocorticoids. Mol Cell Biol Res Comm 2: 145-149.    

36. Hammes S (2003) The further redefining of steroid-mediated signaling. Proc Natl Acad Sci U S A 10:2168-2170.

37. Xiao L, Feng C, Chen Y (2010) Glucocorticoid rapidly enhances NMDA-evoked neurotoxicity by attenuating the NR2A-containing NMDA receptor-mediated ERK ½ activation. Mol Endocrinol 24:497-510.    

38. Heidinger V, Hicks D, Sahel J, et al. (1999) Ability of retinal Müller glial cells to protect neurons against excitotoxicity in vitro depends upon maturation and neuron-glia interactions. Glia 25: 229-239.    

39. Vardimon L (2000) Neuroprotection by glutamine synthetase. IMAJ 2: 46-51.

40. Labow BI, Souba WW, Abcouwer SF (2001) Mechanisms governing the expression of the enzymes of glutamine metabolism, glutaminase and glutamine synthetase. J Nutr 131: 2467-2474.

41. Hertz L, Zielke HR (2004) Astrocytic control of glutamatergic activity: astrocytes as stars of the show. Trends Neurosci 27: 737-743.

42. Gras G, Porcheray F, Samah B, et al. (2006) The glutamate-glutamine cycle as an inducible, protective face of macrophage activation. J Leukoc Biol 80: 1067-1075.    

43. Markowitz AJB, White MG, Kolson DL, et al. (2007) Cellular interplay between neurons and glia: toward a comprehensive mechanism for excitotoxic neuronal loss in neurodegeneration. Cellscience 4: 111-146.

44. Kruchkova Y, Ben-Dror I, Herschkovitz A, et al. (2001) Basic fibroblast growth factor: a potential inhibitor of glutamine synthetase expression in injured neural tissue. J Neurochem 77: 1641-1649.    

45. Shaked I, Ben-Dror I, Vardimon L (2002) Glutamine synthetase enhances the clearance of extracellular glutamate by the neural retina. J Neurochem 83: 574-580.    

46. Zou J, Wang YX, Dou FF, et al. (2010) Glutamine synthetase down regulation reduces astrocyte protection against glutamate excitotoxicity to neurons. Neurochem Int 56: 577-584.    

47. Juurlink BHJ, Schousboe A, Jorgensen OS, et al. (1981) Induction by hydrocortisone of glutamine synthetase in mouse primary astrocyte cultures. J Neurochem 36: 136-142.    

48. Rose K, Goldberg M, Choi D (1993) Cytotoxicity in murine neocortical cell cultures. In Tyson CA, Frazier JM. In vitro biological methods.. San Diego Academics, USA. pp 46-60

49. Koh J, Choi D (1987) Quantitative determination of glutamate-mediated cortical neuronal injury in cell culture by lactate deshydrogenase efflux assay. J Neurosci Methods 20: 83-90.    

50. Harmon J, Thompson B (1982) Glutamine synthetase induction by glucocorticoid in the glucocorticoidsensitive human leukemic cell line CEM-C7. J Cell Sci 110: 155-160.

51. Tanigami H, Rebel A, Martin LJ, et al. (2005) Effect of glutamine synthetase inhibition on astrocytes swelling and altered astroglial protein expression during hyperammonemia in rats. Neurosci 131:437-449.    

52. Zhou Y, Danbolt NC (2014) Glutamate as a neurotransmitter in the healthy brain. J Neural Transm 121:799-817.    

53. Rothman SM, Olney JW (1986) Glutamate and the pathophysiology of hypoxic-ischemic brain damage. Ann Neurol 19: 105-111.    

54. Le Verche V, Ikiz B, Jacquier A, et al. (2011) Glutamate pathway implication in amyotrophic lateral sclerosis: what is the signal in the noise? J Rec Lig Channel Res 4: 1-22.

55. Rothstein JD, Dykes-Hosberg M, Pardo CA, et al. (1996) Knockout of glutamate transporters reveals a major role for astroglial transport in exitotoxicity and clearance of glutamate. Neuron 16: 675-686.    

56. Buisson A, Nicole O, Docagne F, et al. (1998) Up-regulation of a serine protease inhibitor in astrocytes mediates the neuroprotective activity of Transforming Growth Factor β1. FASEB J 12: 1683-1691.

57. Eid T, Ghosh A, Wang Y, et al. (2008) Recurrent seizures and brain pathology after inhibition of glutamine synthetase in the hippocampus in rats. Brain 131: 2061-2070.    

58. Zschocke J, Bayatti N, Clement AM, et al. (2005) Differential promotion of glutamate transporter expression and function by glucocorticoids in astrocytes from various brain regions. J Biol Chem 280:34924-34932.    

59. Fan Z, Sehm T, Rauh M, et al. (2014) dexamethasone alleviates tumor-associated brain damage and angiogenesis. PloS ONE 9: e93264

60. Nichols NR, Agolley D, Zieba M, et al. (2005) Glucocorticoid regulation of glial responses during hippocampal neurodegeneration and regeneration. Brain Res Rev 48: 287-301.    

61. Abraham I, Veenema AH, Nyakas C, et al. (1997) Effect of corticosterone and adrenalectomy on NMDA-induced cholinergic cell death in rat magnocellular nucleus basalis. J Neuroendocrinol 9:713-720.

62. Kurkowska-Jastrzebska I, Litwin T, Joniec I, et al. (2004) Dexamethasone protects against dopaminergic neurons damage in a mouse model of Parkinson's disease. Internat Immunopharmacol 4: 1307-1318.    

Copyright Info: © 2015, Dominique Duval, et al., licensee AIMS Press. This is an open access article distributed under the terms of the Creative Commons Attribution Licese (http://creativecommons.org/licenses/by/4.0)

Download full text in PDF

Export Citation

Article outline

Show full outline
Copyright © AIMS Press All Rights Reserved