Donepezil attenuates excitotoxic damage induced by membrane depolarization of cortical neurons exposed to veratridine.
Long-lasting membrane depolarization in cerebral ischemia causes neurotoxicity via increases of intracellular sodium concentration ([Na+]i) and calcium concentration ([Ca2+]i). Donepezil has been shown to exert neuroprotective effects in an oxygen-glucose deprivation model. In the present study, we examined the effect of donepezil on depolarization-induced neuronal cell injury resulting from prolonged opening of Na+ channels with veratridine in rat primary-cultured cortical neurons. Veratridine (10 microM)-induced neuronal cell damage was completely prevented by 0.1 microM tetrodotoxin. Pretreatment with donepezil (0.1-10 microM) for 1 day significantly decreased cell death in a concentration-dependent manner, and a potent NMDA receptor antagonist, dizocilpine (MK801), showed a neuroprotective effect at the concentration of 10 microM. The neuroprotective effect of donepezil was not affected by nicotinic or muscarinic acetylcholine receptor antagonists. We further characterized the neuroprotective properties of donepezil by measuring the effect on [Na+]i and [Ca2+]i in cells stimulated with veratridine. At 0.1-10 microM, donepezil significantly and concentration-dependently reduced the veratridine-induced increase of [Ca2+]i, whereas MK801 had no effect. At 10 microM, donepezil significantly decreased the veratridine-induced increase of [Na+]i. We also measured the effect on veratridine-induced release of the excitatory amino acids, glutamate and glycine. While donepezil decreased the release of glutamate and glycine, MK801 did not. In conclusion, our results indicate that donepezil has neuroprotective activity against depolarization-induced toxicity in rat cortical neurons via inhibition of the rapid influx of sodium and calcium ions, and via decrease of glutamate and glycine release, and also that this depolarization-induced toxicity is mediated by glutamate receptor activation.
Tsukuba Research Laboratories, Eisai Co., Ltd., 5-1-3 Tokodai, Tsukuba-shi, Ibaraki 300-2635, Japan. s-akasofu@hhc.eisai.co.jp <s-akasofu@hhc.eisai.co.jp>
Shigeru
S
Akasofu
Kohei
K
Sawada
Takashi
T
Kosasa
Hiroe
H
Hihara
Hiroo
H
Ogura
Akinori
A
Akaike
D000818:Animals; D002118:Calcium / Q000378:metabolism; D061945:Caspase Inhibitors; D002478:Cells, Cultured; D002540:Cerebral Cortex / Q000187:drug effects* / Q000502:physiology; D002800:Cholinesterase Inhibitors / Q000494:pharmacology*; D000077265:Donepezil; D018698:Glutamic Acid / Q000378:metabolism; D005998:Glycine / Q000378:metabolism; D007189:Indans / Q000494:pharmacology*; D008564:Membrane Potentials / Q000187:drug effects; D018696:Neuroprotective Agents / Q000494:pharmacology*; D010880:Piperidines / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D016194:Receptors, N-Methyl-D-Aspartate / Q000037:antagonists & inhibitors; D012964:Sodium / Q000378:metabolism; D013779:Tetrodotoxin / Q000494:pharmacology; D014701:Veratridine / Q000633:toxicity*
D061945:Caspase Inhibitors; D002800:Cholinesterase Inhibitors; D007189:Indans; D018696:Neuroprotective Agents; D010880:Piperidines; D016194:Receptors, N-Methyl-D-Aspartate; D018698:Glutamic Acid; D013779:Tetrodotoxin; D014701:Veratridine; D000077265:Donepezil; D012964:Sodium; D002118:Calcium; D005998:Glycine