Acetylcholinesterase inhibitors attenuate angiogenesis

Donepezil {(RS)-2-[(1-benzyl-4-piperidyl)methyl]-5,6-dimethoxy-2,3-dihydroinden-1-one} is a reversible acetylcholinesterase inhibitor and used for treatment of patients with AD (Alzheimer's disease). Recent studies showed that treatment with donepezil reduced production of inflammatory cytokines in PBMCs (peripheral blood mononuclear cells). It was also reported that muscle-derived inflammatory cytokines play a critical role in neovascularization in a hindlimb ischaemia model. We sought to determine whether donepezil affects angiogenesis. A hindlimb ischaemia model was created by unilateral femoral artery ligation. Blood flow recovery examined by laser Doppler perfusion imaging and capillary density by immunohistochemical staining of CD31-positive cells in the ischaemic hindlimb were significantly decreased in donepezil- and physostigmine-treated mice compared with control mice after 2 weeks. Donepezil reduced expression of IL (interleukin)-1β and VEGF (vascular endothelial growth factor) in the ischaemic hindlimb. Intramuscular injections of IL-1β to the ischaemic hindlimb reversed the donepezil-induced VEGF down-regulation and the anti-angiogenic effect. Hypoxia induced IL-1β expression in C2C12 myoblast cells, which was inhibited by pre-incubation with ACh (acetylcholine) or LY294002, a PI3K (phosphoinositide 3-kinase) inhibitor. Donepezil inhibited phosphorylation of Akt [also known as PKB (protein kinase B)], a downstream kinase of PI3K, in the ischaemic hindlimb. These findings suggest that cholinergic stimulation by acetylcholinesterase inhibitors suppresses angiogenesis through inhibition of PI3K-mediated IL-1β induction, which is followed by reduction of VEGF expression. Acetylcholinesterase inhibitor may be a novel anti-angiogenic therapy.