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Neurotransmitters

Explanations > Brain stuff > Neurotransmitters

Neurotransmitter function | Types of neurotransmitter | Neurotransmitter systems | See also

Neurotransmitters are critical components of the transmission system between neurons.

Production

Neurotransmitters are produced in neurons by the action of synthetic enzymes on precursor substances.

Neurotransmitter function

When a neuron 'fires', neurotransmitters are released from vesicules in the pre-synaptic terminal buttons (of the firing neuron) and travel across the synapse to the post-synaptic membrane (of the target neuron) where they dock with postsynaptic receptors where they act to open particular ion channels that allows in ions and so trigger or inhibit an action potential in the postsypnaptic neuron, thus propagating or preventing a chain of neural firing. In this way we think and feel, and the functions of our body are controlled.

After use, neurotransmitters are either re-absorbed and re-used, or destroyed, either by special chemical or after transport to the liver or kidneys.

Types of neurotransmitter

There is a wide range of neurotransmitters, although relatively few are of major interest in many cases.

Small-molecule neurotransmitters

These neurotransmitters are perhaps those which are most commonly discussed.

Family	Name	Abbrev.	Function
(none)	Acetylcholine	ACh	Motor
Monoamines	Norepinephrine	NA
	Dopamine	DA	Reward +
	Seratonin	5-HT	Mood, sleep, temperature
	Melatonin
	Histamine
	Epinephrine	Epi
	Tyramine
Amino acids	Glutamate		Brain excitation
	Gamma-aminobutyric acid	GABA	Brain inhibition
	Aspartate
	Glycine	Gly or G	Spinal cord inhibition
Purines	Adenosine
	ATP
	GTP

Other neurotransmitters

In addition to the small molecule neurotransmitters, there are a number of additional molecules that act as neurotransmitters.

Here are brief notes about a few:

In more detail, this would include:

Family	Name	Abbrev.	Function
Gastrins	Gastrin
	Cholecystokinin	CCK
Neuropeptide Y	Neuropeptide Y	NY
	Pancreatic polypeptide	PP
	Peptide YY	PYY
Opioids	Corticotropin	ACTH
	Dynorphin
	Endorphin
	Enkephaline
Secretins	Secretin
	Motilin
	Glucagon
	Vasoactive intestinal peptide
	Growth hormone-releasing factor	GRF
Somtostatins	Somtostatin
Tachykinins	Neurokinin A
	Neurokinin B
	Substance P

Other molecules that get released into the synapse and are sometimes considered as neurotransmitters include zinc ions and gases nitric oxide and carbon monoxide.

Neurotransmitter systems

There are a number of systems or 'circuits' which activate a large area of the brain at once in volume transmission. An effect of this is that drugs targeting the key neurotransmitter get to affect the whole system in one go.

System	Pathway	Function
Norepinephrine	Locus coeruleus	Arousal and reward
Dopamine system	Mesocortical pathway Mesolimbic pathway Nigrostriatal pathway Tuberoinfundibular pathway	Motor system, reward, thinking, nausea
Seratonin system	Dorsal raphe nucleus	Mood, satiation, sleep, pain reduction
Cholinergic system		Learning, short-term memory, arousal, reward