Study of neuroprotection of donepezil, a therapy for Alzheimer's disease.

Donepezil is a potent acetylcholinesterase inhibitor used for the treatment of Alzheimer's disease. Although acetylcholinesterase inhibitors are thought to be symptomatic treatment of Alzheimer's disease, it is not clear whether they are effective against progressive degeneration of neuronal cells. In this study, we investigated the neuroprotective effects of donepezil against ischemic damage, N-methyl-d-aspartate (NMDA) excitotoxicity, and amyloid-beta (Aβ) toxicity using rat brain primary cultured neurons. Lactate dehydrogenase (LDH) released into the culture medium was measured as a marker of neuronal cell damage. As an ischemic damage model, we used oxygen–glucose deprivation in rat cerebral cortex primary cultured neurons. Pretreatment with donepezil (0.1, 1 and 10μM) significantly decreased LDH release in a concentration-dependent manner. However, other acetylcholinesterase inhibitors (galantamine, tacrine and rivastigmine) did not significantly decrease LDH release. In a NMDA excitotoxicity model, pretreatment with donepezil (0.1, 1 and 10μM) decreased the LDH release in a concentration-dependent manner. In binding assay for glutamate receptors, donepezil at 100μM only slightly inhibited binding to the glycine and polyamine sites on NMDA receptor complex. We further examined the effect of donepezil on Aβ (1–40)- and Aβ (1–42)-induced toxicity in primary cultures of rat septal neurons. Pretreatment with donepezil (0.1, 1 and 10μM) significantly decreased LDH release induced by Aβs in a concentration-dependent manner. However, other acetylcholinesterase inhibitors (galantamine and tacrine) and NMDA receptor antagonists (memantine and dizocilpine (MK801)) did not significantly decrease LDH release.