Neurotransmitter must be broken down once it reaches the post-synaptic cell to prevent further excitatory or inhibitory signal transduction. For example, [[acetylcholine| acetylcholine, (ACH)]] (an excitatory neurotransmitter), is broken down by [[acetylcholinesterase]] (AchE). [[Choline]] is taken up and recycled by the pre-synaptic neuron to synthesize more ACH.
Other neurotransmitters such as [[dopamine]] are able to [[diffusion|diffuse]] away from their targeted synaptic junctions and are eliminated from the body via the kidneys, or destroyed in the liver. Each neurotransmitter has very specific degradation pathways at regulatory points, which may be the target of the body's own regulatory system or [[recreational drug]]s.
