acetylcholinesterase

n. (AChE) The enzyme present at neuromuscular synaptic junctions, in the parasympathetic system and in the brain, which inactivates excess acetylcholine (ACh). AChE thus reduces or halts the activity of ACh by breaking it down into choline and acetate, which are not neurotransmitters. Because of the presence of AChE at the synapse, cholinergic-initiated activity is brief in duration, easily interrupted, rather than prolonged, as with adrenergic (epinephrinergic) transmission. When AChE is pharmacologically blocked, cholinergic activity is more robust and prolonged.    - VS