1355259

N-methyl-D-aspartate exposure blocks glutamate toxicity in cultured cerebellar granule cells.

Article date: 1992/8/1

PubMed ID: 1355259

Journal name: Molecular pharmacology (ISSN: 0026-895X)

ABSTRACT

Exposure of cultured cerebellar granule cells to glutamate results in a concentration-dependent (EC50 = 22.7 +/- 0.4 microM) and delayed (24-72 hr) neurotoxicity, which is blocked by the specific N-methyl-D-aspartate (NMDA) receptor antagonists 2-amino-5-phosphovalerate and MK-801 but is unaffected by the non-NMDA receptor antagonists 6-cyano-7-nitroquinoxaline-2,3-dione and 6,7-dinitroquinoxaline-2,3-dione. Although glutamate toxicity in these cells is mediated by the NMDA subtype of glutamate receptor, pretreatment of cerebellar granule cells with subtoxic concentrations of NMDA markedly antagonizes the neurotoxic actions of glutamate, with an IC50 of 55 +/- 4 microM. The neuroprotective effect of NMDA requires a preincubation time of approximately 120 min to be fully manifested and does not require the presence of NMDA during glutamate exposure. These data demonstrate that NMDA receptors mediate both neurotoxicity and neuroprotection in cerebellar granule cells. Among four glutamate receptor agonists tested (NMDA, quisqualate, ibotenate, and kainate), only NMDA was able to provide a robust neuroprotection against glutamate toxicity. Quisqualate was neither neurotoxic nor neuroprotective, whereas ibotenate, which was nontoxic by itself, induced a small degree of neuroprotection. In contrast, kainate, which was neurotoxic to cerebellar granule cells, also provided considerable neuroprotection against glutamate toxicity. Because preincubation of cerebellar granule cells with NMDA fails to alter NMDA receptor-mediated phosphoinositide hydrolysis or the specific binding of [3H]MK-801 to NMDA receptors, it appears that the neuroprotective effects of NMDA are not due to NMDA receptor desensitization.

Author List: Chuang D M, Gao X M, Paul S M

Publication Types: Comparative Study; Journal Article

Substances mentioned in the article: Culture Media; Excitatory Amino Acid Antagonists; Glutamates; Receptors, Glutamate; Receptors, N-Methyl-D-Aspartate; Receptors, Neurotransmitter; Tritium; Ibotenic Acid; Aspartic Acid; Glutamic Acid; Ouabain; N-Methylaspartate; Quisqualic Acid; Magnesium; Glucose; Kainic Acid;

Mesh terms: Animals; Aspartic Acid/pharmacokinetics; Cells, Cultured; Cerebellum/cytology; Culture Media; Cytoplasmic Granules/drug effects; Excitatory Amino Acid Antagonists; Glucose/pharmacology; Glutamates/metabolism; Glutamic Acid; Ibotenic Acid/pharmacology; Kainic Acid/pharmacology; Magnesium/pharmacology; N-Methylaspartate/pharmacology; Neurons/drug effects; Ouabain/metabolism; Quisqualic Acid/pharmacology; Rats; Rats, Inbred Strains; Receptors, Glutamate; Receptors, N-Methyl-D-Aspartate/drug effects; Receptors, Neurotransmitter/drug effects; Sensitivity and Specificity; Tritium;

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