Donepezil ameliorates Aβ pathology but not tau pathology in 5xFAD mice.

The cholinesterase inhibitor donepezil is used to improve Aβ pathology and cognitive function in patients with Alzheimer's disease (AD). However, the impact of donepezil on tau pathology is unclear. Thus, we examined the effects of donepezil on Aβ and tau pathology in 5xFAD mice (a model of AD) in this study. We found that intraperitoneal injection of donepezil (1 mg/kg, i.p.) exhibited significant reductions in Aβ plaque number in the cortex and hippocampal DG region. In addition, donepezil treatment (1 mg/kg, i.p.) reduced Aβ-mediated microglial and, to a lesser extent, astrocytic activation in 5xFAD mice. However, neither intraperitoneal/oral injection of donepezil nor oral injection of rivastigmine altered tau phosphorylation at Thr212/Ser214 (AT100), Thr396, and Thr231 in 5xFAD mice. Surprisingly, we observed that intraperitoneal/oral injection of donepezil treatment significantly increased tau phosphorylation at Thr212 in 5xFAD mice. Taken together, these data suggest that intraperitoneal injection of donepezil suppresses Aβ pathology but not tau pathology in 5xFAD mice.