摘要:
The reduction of acetylcholinesterase (AChE) activity in the brain has been measured in dementia disorders such as Alzheimer's disease and dementia with Lewy bodies using C-11-labeled acetylcholine analogues, N-[C-11]methylpiperidin-4-yl acetate and propionate, and positron emission tomography (PET). Our aim was to develop an F-18-labeled acetylcholine analogue useful for brain AChE mapping with PET, since F-18, with a longer half-life, has advantages over C-11. In a preliminary study, a series of N-[C-14]ethylpiperidin-3-yl or -4yl-methanol esters (acetyl and propionyl esters) were newly designed and evaluated in vitro regarding the reactivity with and specificity to AChE using purified human enzymes, leading to a novel F-18-labeled acetylcholine analogue, N-[F-18]fluoroethylpiperidin-4-ylmethyl acetate. In rat experiments, the F-18-labeled candidate showed desirable properties for PET AChE measurement: high brain uptake of the authentic ester, high AChE specificity, a moderate hydrolysis rate, and low membrane permeability (metabolic trapping) of the metabolite.