Ca(2+)- and Cl(-)-dependent, NMDA receptor-mediated neuronal death induced by depolarization in rat hippocampal organotypic cultures.
The neurotoxicity induced by depolarization with high-K+ was investigated in rat hippocampal organotypic slice cultures. The exposure of cultures to 90 mM K+ solution for 30 min caused a severe neuronal injury in CA1 region while less damage was observed in CA3 and dentate gyrus over the following day. This neurotoxicity was prevented in a concentration dependent manner by NMDA antagonist MK-801 or CPP. Non-NMDA antagonist, DNQX, had no protective effect. Omission of Ca2+ from the exposure solution prevented the neurotoxicity. Voltage-dependent Ca2+ channel blockers, nifedipine and flunarizine, failed to prevent the neurotoxicity. These results suggest that the Ca2+ influx through the NMDA receptor is predominantly involved in this neurotoxicity. Apparent tissue swelling was observed immediately after the depolarization. This swelling was completely inhibited by omission of Cl- from the exposure solution, accompanied with complete protection against neurotoxicity. This suggests that Cl(-)-dependent tissue swelling also largely contributes to the neurotoxicity. Depolarization with application of MK-801 (10 microM) or omission of Ca2+ from the solution still caused apparent swelling, despite these treatment protected neuronal death. We hypothesize that Cl(-)-dependent tissue swelling may be involved in the release of the excitatory amino acid, which activates the NMDA receptor.
Takahashi
M
M
Tsukuba Research Laboratories, Upjohn Pharmaceuticals Ltd., Ibaraki-ken, Japan.
Liou
S Y
SY
Kunihara
M
M
D000818:Animals; D000831:Animals, Newborn / Q000502:physiology; D002118:Calcium / Q000502:physiology*; D002121:Calcium Channel Blockers / Q000494:pharmacology; D016923:Cell Death / Q000187:drug effects / Q000502:physiology; D002712:Chlorides / Q000502:physiology*; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D006624:Hippocampus / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D009467:Neuromuscular Depolarizing Agents / Q000633:toxicity*; D009474:Neurons / Q000187:drug effects / Q000502:physiology*; D009924:Organ Culture Techniques; D011188:Potassium / Q000633:toxicity*; D051381:Rats; D016194:Receptors, N-Methyl-D-Aspartate / Q000187:drug effects / Q000502:physiology*; D015222:Sodium Channels / Q000187:drug effects / Q000378:metabolism
D002121:Calcium Channel Blockers; D002712:Chlorides; D018691:Excitatory Amino Acid Antagonists; D009467:Neuromuscular Depolarizing Agents; D016194:Receptors, N-Methyl-D-Aspartate; D015222:Sodium Channels; D011188:Potassium; D002118:Calcium