Source:
"Neurotransmitters for Kids"; Eric H. Chudler, Ph.D.; University of Washington; Seattle, Washington 98195-6540
Descriptions
taken from the University of Washington Research Center
Inactivation
of Neurotransmitters
The
action of neurotransmitters can be stopped by four different
mechanisms
1.
Diffusion: the neurotransmitter
drifts away, out of the synaptic cleft where it can no longer
act on a receptor.
Diffusion
2.
Enzymatic degradation (deactivation):
a specific enzyme changes the structure of the neurotransmitter
so it is not recognized by the receptor. For example, acetylcholinesterase
is the enzyme that breaks acetylcholine into choline and acetate.
Enzymatic
degradation
3.
Glial cells: astrocytes remove
neurotransmitters from the synaptic cleft.
Astrocyte
Image courtesy of Biodidac
4.
Reuptake: the whole neurotransmitter
molecule is taken back into the axon terminal that released
it. This is a common way the action of norepinephrine, dopamine
and serotonin is stopped...these neurotransmitters are removed
from the synaptic cleft so they cannot bind to receptors.
