Sub-second pharmacokinetics of acetylcholine release and recycling in the cerebral cortex

PROJECT SUMMARY This project will investigate the potential of sub-pallidal basal forebrain activation to increase acetylcholine levels in the cerebral cortex. Electrical stimulation of the basal forebrain is a human translatable therapy being currently evaluated in clinical trials. Stimulating this brain region results in increases in acetylcholine levels throughout the cerebral cortex and increases in blood flow. The release of acetylcholine in response to continuous pulse train stimulation adapts to baseline within a few minutes, whereas intermittent stimulation results in increases in acetylcholine levels. We plan to study intermittent stimulation in three aims which seek to optimize it for acetylcholine release and study the cellular mechanisms by which it is released, cleaved to acetate and choline, transported back into the axon terminal, and readied for release again. In the first aim, new imaging technology enables the direct visualization of changing acetylcholine levels in the cerebral cortex, and this new technology, a fluorescent acetylcholine receptor, will be used to evaluate and optimize the stimulation. Second, studies will apply pharmacological agents to alter cholinergic processing by inhibiting acetylcholinesterase or the feedback autoreceptor. Third, a viral vector approach will be used to manipulate key molecules in the circuit surrounding the cholinergic axon that are relevant for recycling the molecules of acetylcholine from release, to hydrolysis, to choline transport, to re-conjugation, and to re-packaging in a vesicle. Overall, this proposal leverages the expertise of three different PIs through the multi-PI mechanism using a broad interdisciplinary approach to investigate an experimental therapy for clinical application in humans.