ISSN:
1471-4159
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Medicine
Notes:
Abstract: We have investigated the mechanisms of cell death induced by long-term exposure to the glutamate receptor agonist (S)-α-amino-3-hydroxy-5-methyl-4-isoxazolepropionate [(S)-AMPA]. Using primary cultures of pure neurons (95%) grown in serum-free conditions, we found that 24-h exposure to (S)-AMPA (0.01–1,000 µM) induced concentration-dependent neuronal cell death (EC50 = 3 ± 0.5 µM) with cellular changes including neurite blebbing, chromatin condensation, and DNA fragmentation, indicative of apoptosis. (S)-AMPA induced a delayed cell death with DNA fragmentation occurring in ∼50% of cells at concentrations between 100 and 300 µM detected using terminal transferase-mediated dUTP nick end-labeling (TUNEL) and agarose gel electrophoresis. Apoptotic chromatin condensation was detected using 4,6-diamidino-2-phenylindole, a fluorescent DNA binding dye. Cell death induced by (S)-AMPA was attenuated by the AMPA receptor-selective antagonist LY293558 (10 µM) and the non-NMDA receptor antagonist 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX; 50 µM), yielding EC50 values of 73 ± 5 and 265 ± 8 µM, respectively, and was unaffected by the NMDA receptor antagonist MK-801 (10 µM). The number of apoptotic nuclei induced by 300 µM (S)-AMPA (57%) was also reduced substantially by the antagonists LY293558 and CNQX, with only 20% and 18% of neurons, respectively, staining TUNEL-positive at 24 h. In addition, cycloheximide (0.5 µg/ml) also inhibited (S)-AMPA-induced DNA fragmentation and cell death. Our results show that long-term exposure to AMPA can induce substantial neuronal death involving apoptosis in cultured cortical neurons, suggesting a wide involvement of AMPA-sensitive glutamate receptors in excitotoxic injury and neurodegenerative pathologies.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1046/j.1471-4159.1997.69020617.x
Permalink
