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| Research article summary (published 3 Jul 2005): |
The excitoprotective effect of N-methyl-D-aspartate receptors is mediated by a brain-derived neurotrophic factor autocrine loop in cultured hippocampal neurons.
Full Abstract
The neuroprotective effect and molecular mechanisms underlying preconditioning with N-methyl-D-aspartate (NMDA) in cultured hippocampal neurons have not been described. Pre-incubation with subtoxic concentrations of the endogenous neurotransmitter glutamate protects vulnerable neurons against NMDA receptor-mediated excitotoxicity. As a result of physiological preconditioning, NMDA significantly antagonizes the neurotoxicity resulting from subsequent exposure to an excitotoxic concentration of glutamate. The protective effect of glutamate or NMDA is time- and concentration-dependent, suggesting that sufficient agonist and time are required to establish an intracellular neuroprotective state. In these cells, the TrkB ligand, brain-derived neurotrophic factor (BDNF) attenuates glutamate toxicity. Therefore, we tested the hypothesis that NMDA protects neurons via a BDNF-dependent mechanism. Exposure of hippocampal cultures to a neuroprotective concentration of NMDA (50 microM) evoked the release of BDNF within 2 min without attendant changes in BDNF protein or gene expression. The accumulated increase of BDNF in the medium is followed by an increase in the phosphorylation (activation) of TrkB receptors and a later increase in exon 4-specific BDNF mRNA. The neuroprotective effect of NMDA was attenuated by pre-incubation with a BDNF-blocking antibody and TrkB-IgG, a fusion protein known to inhibit the activity of extracellular BDNF, suggesting that BDNF plays a major role in NMDA-mediated survival. These results demonstrate that low level stimulation of NMDA receptors protect neurons against glutamate excitotoxicity via a BDNF autocrine loop in hippocampal neurons and suggest that activation of neurotrophin signaling pathways plays a key role in the neuroprotection of NMDA.
Author information
Author/s: Jiang, Xueying (X); Tian, Feng (F); Mearow, Karen (K); Okagaki, Peter (P); Lipsky, Robert H (RH); Marini, Ann M (AM);
Affiliation: Department of Neurology and Division of Neuroscience, Uniformed Services University of the Health Sciences, Bethesda, Maryland 20814, USA.
Journal and publication information
Publication Type: Comparative Study; Journal Article; Research Support, U.S. Gov't, Non-P.H.S.
Journal: Journal of neurochemistry (J Neurochem), published in England. (Language: eng)
Reference: 2005-Aug; vol 94 (issue 3) : pp 713-22
Dates: Created 2005/07/21; Completed 2005/09/19; Revised 2007/11/15;
PMID: 16000165, status: MEDLINE (last retrieved date: 2/18/2009)
Sourced from the National Library of Medicine. Abstract text and other information may be subject to copyright.
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Associated Chemicals: Antibodies (0) ; Brain-Derived Neurotrophic Factor (0) ; Excitatory Amino Acid Agonists (0) ; Excitatory Amino Acid Antagonists (0) ; Receptors, N-Methyl-D-Aspartate (0) ; 6-Cyano-7-nitroquinoxaline-2,3-dione (115066-14-3) ; Tyrosine (55520-40-6) ; Glutamic Acid (56-86-0) ; N-Methylaspartate (6384-92-5) ; Dizocilpine Maleate (77086-22-7) ; Receptor, trkB (EC 2.7.1.112)Related articles
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