Rat cerebellar granule cells are protected from glutamate-induced excitotoxicity by S-nitrosoglutathione but not glutathione.
In cultured rat cerebellar granule cells, glutamate or N-methyl-d-aspartate (NMDA) activation of the NMDA receptor caused a sustained increase in cytosolic Ca(2+) levels ([Ca(2+)](i)), reactive oxygen species (ROS) generation, and cell death (respective EC(50) values for glutamate were 12, 30, and 38 microM) but no increase in caspase-3 activity. Removal of extracellular Ca(2+) blocked all three glutamate-induced effects, whereas pretreatment with an ROS scavenger inhibited glutamate-induced cell death but had no effect on the [Ca(2+)](i) increase. This indicates that glutamate-induced cell death is attributable to [Ca(2+)](i) increase and ROS generation, and the [Ca(2+)](i) increase precedes ROS generation. Apoptotic cell death was not seen until 24 h after exposure of cells to glutamate. S-nitrosoglutathione abolished glutamate-induced ROS generation and cell death, and only a transient [Ca(2+)](i) increase was seen; similar results were observed with another nitric oxide (NO) donor, S-nitroso-N-acetylpenicillamine, but not with glutathione, which suggests that the effects were caused by NO. The transient [Ca(2+)](i) increase and the abolishment of ROS generation induced by glutamate and S-nitrosoglutathione were still seen in the presence of an ROS scavenger. Glial cells, which were present in the cultures used, showed no [Ca(2+)](i) increase in the presence of glutamate, and glutamate-induced granule cell death was independent of the percentage of glial cells. In conclusion, NO donors protect cultured cerebellar granule cells from glutamate-induced cell death, which is mediated by ROS generated by a sustained [Ca(2+)](i) increase, and glial cells provide negligible protection against glutamate-induced excitotoxicity.
Li
Chung-Yu
CY
Department of Biochemistry, National Defense Medical Center, Taipei 114, Taiwan, Republic of China.
Chin
Ting-Yu
TY
Chueh
Sheau-Huei
SH
D000818:Animals; D002258:Carbonyl Cyanide m-Chlorophenyl Hydrazone / Q000494:pharmacology; D002478:Cells, Cultured; D002531:Cerebellum / Q000166:cytology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D018698:Glutamic Acid / Q000633:toxicity*; D005978:Glutathione / Q000494:pharmacology*; D005998:Glycine / Q000494:pharmacology; D007476:Ionophores / Q000494:pharmacology; D008274:Magnesium / Q000494:pharmacology; D009474:Neurons / Q000166:cytology / Q000187:drug effects* / Q000502:physiology*; D018696:Neuroprotective Agents / Q000494:pharmacology*; D009498:Neurotoxins / Q000494:pharmacology; D009569:Nitric Oxide / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D017382:Reactive Oxygen Species / Q000378:metabolism; D016194:Receptors, N-Methyl-D-Aspartate / Q000378:metabolism; D026422:S-Nitrosoglutathione / Q000494:pharmacology*; D019284:Thapsigargin / Q000494:pharmacology
D004791:Enzyme Inhibitors; D018691:Excitatory Amino Acid Antagonists; D007476:Ionophores; D018696:Neuroprotective Agents; D009498:Neurotoxins; D017382:Reactive Oxygen Species; D016194:Receptors, N-Methyl-D-Aspartate; D009569:Nitric Oxide; D018698:Glutamic Acid; D002258:Carbonyl Cyanide m-Chlorophenyl Hydrazone; D026422:S-Nitrosoglutathione; D019284:Thapsigargin; D005978:Glutathione; D008274:Magnesium; D005998:Glycine