Neurotransmitters
Neurotransmitters are chemical signals that neurons use to communicate with other neurons and different cells. Most have other uses in the body as well.
Unlike the neuromuscular junction, neuron synapses have more subtle and complex characteristics. Neurotransmitters can stimulate, inhibit, or modulate the postsynaptic neuron.
- acetylcholine - excitatory
- dopamine - excitatory
- GABA - inhibitory
- glutamate - excitatory
- norepinephrine - the primary sympathetic neurotransmitter
- serotonin - excitatory
- histamine
- opiod peptides
- tachykinins
- endocannabinoids
The four main criteria used to define neurotransmitters are:
- synthesized endogenously
- available in presynaptic neuron in sufficient quantities to exert effect on post-synaptic neuron
- if externally administered, mimics endogenous substance
- mechanism for inactivation exists
Trafficking Neurotransmitters
There are two main fashions of transporting neurotransmitters down the axon.
Slow axonal transport occurs via synthesis in the cell body, are packaged in the golgi, and are then transported down the axon.
Fast transport...
Neurotransmitter Production
In general, decarboxylation activates compunds, while deamination inactivates them.
- Tyrosine is used to synthesize dopamine, norephephrine, and epinephrine, sequentially.
- Histidine is used to synthesize histamine.
- Tryptophan is used to synthesize 5-hydroxy-tryptophan and serotonin.
Ionotropic and Met