The brain's chemical messengers at a glance — amino acids, monoamines, acetylcholine, peptides and gases — what makes something a neurotransmitter, and what the major ones do.
Neurotransmitters & Brain Chemistry
Beginner
Neurotransmitters: An Overview
The Editors
November 2, 2025
3 min read
In plain English
Neurotransmitters are chemicals that neurons release to send messages to other cells. There are dozens. A few — glutamate and GABA — handle most of the brain's fast 'go' and 'stop' signals. Others, like dopamine and serotonin, tune whole brain networks up or down.
Beginner level: No background needed. Everyday language, everyday examples — the place to start.
Concepts to know first
Go deeper next
A neurotransmitter is a chemical that a neuron releases at a synapse to influence another cell. More than a hundred substances act as transmitters or modulators. Classically, a substance counts as a neurotransmitter if it is made in the neuron, released when the neuron fires, acts on receptors on the target cell, and is removed by a specific mechanism.
The main families
Amino acids are the workhorses. Glutamate is the main excitatory transmitter in the brain; GABA is the main inhibitory one; glycine is a major inhibitory transmitter in the spinal cord and brainstem.
Monoamines are made by small clusters of neurons deep in the brain whose axons spread widely. Dopamine is involved in movement, motivation and learning from reward; noradrenaline (norepinephrine) in arousal and attention; serotonin in mood, sleep, appetite and much more; histamine in wakefulness.
Acetylcholine, the first transmitter discovered, controls muscles and plays roles in attention, memory and the autonomic nervous system.
Neuropeptides — short chains of amino acids such as endorphins, substance P, oxytocin and orexin — are released more slowly, often alongside a classical transmitter, and have longer-lasting effects.
Some unusual messengers break the rules: nitric oxide, a gas, diffuses freely from cell to cell, and the endocannabinoids travel backwards across synapses.
Fast messaging versus modulation
It helps to think of two jobs. Glutamate and GABA do point-to-point messaging — the brain's precise wiring. Monoamines, acetylcholine and peptides do much of the modulation, changing how whole networks respond, a bit like adjusting the volume, contrast and colour on a screen rather than drawing the picture.
A caution about simple labels
Popular culture calls dopamine "the pleasure chemical" and serotonin "the happiness chemical". These labels are misleading: each transmitter does many jobs depending on which receptors and circuits are involved.
Everyday examples & things to try
Analogy
Messages versus mood lighting
Glutamate and GABA are like the words in a conversation — precise, fast, specific. Dopamine, serotonin and noradrenaline are like the lighting and background music in the room — they change how every word lands.
Real world
Co-release
Many neurons release more than one transmitter. A single neuron might release GABA for fast inhibition and a neuropeptide that acts only when it fires rapidly — like sending a normal message, plus a special memo when things get busy.
Key takeaways
- Glutamate (excitatory) and GABA (inhibitory) carry most fast signals in the brain.
- Monoamines, acetylcholine and neuropeptides largely modulate networks.
- 'Pleasure chemical'-style labels oversimplify; effects depend on receptors and circuits.
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