Summary
Serotonin influences mood, sleep and appetite; SSRIs raise its levels at synapses.
In depth
Produced mainly in the raphe nuclei and gut. Roles in mood, sleep, appetite and pain. Antidepressants such as SSRIs increase synaptic serotonin, but their effect takes weeks, suggesting adaptations.
Serotonin has at least 14 receptor types. It also regulates gut motility. Low serotonin is not a simple cause of depression.
Common mistake: depression is not just a 'chemical imbalance'.
Serotonin (5-HT) is made from tryptophan, with about 90 percent in the gut where it regulates motility, and the rest in the brain from raphe nuclei projecting widely. There are at least 14 receptor subtypes; many are GPCRs and 5-HT3 is a channel. Psychedelics such as psilocybin and LSD act on 5-HT2A receptors and are being tested for depression. MDMA releases serotonin.
The monoamine hypothesis of depression, that low serotonin causes it, is now considered too simple: SSRIs raise serotonin quickly, but benefits take weeks, suggesting plasticity changes. Other drugs include SNRIs, MAO inhibitors and tricyclics. Serotonin syndrome is a dangerous overdose with fever and agitation. Platelets also use serotonin for clotting.
Frequently asked questions
What is Serotonin and Mood?
Serotonin influences mood, sleep and appetite; SSRIs raise its levels at synapses.
Which area of biology covers Serotonin and Mood, and how advanced is it?
Serotonin and Mood is one of the 54 topics in Neuroscience. It is rated Intermediate, so it suits learners who already know the core vocabulary. Related topics in this area include Neuropharmacology, Nervous System, NMDA Receptors.
Why does Serotonin and Mood matter?
Mood disorders affect around 1 in 5 people at some time, so understanding the biology is important.
Can you give an example of Serotonin and Mood?
MDMA releases serotonin massively.
What should I learn before Serotonin and Mood?
Work through the Beginner topics in Neuroscience first, such as Nervous System, Neuron, Central and Peripheral Nervous Systems, then return to Serotonin and Mood. Intermediate topics assume the Beginner vocabulary.
What topics are related to Serotonin and Mood?
The closest topics to Serotonin and Mood are Neuropharmacology, Nervous System, NMDA Receptors, Synaptic Plasticity. Comparing them side by side is a good way to see how the ideas connect.
How can I check that I understand Serotonin and Mood?
Read the summary and the in-depth section, then use the quick check on the interactive lesson for Serotonin and Mood. To practise the whole of Neuroscience, use the Neuroscience quiz.
How is Serotonin and Mood different from Neuropharmacology?
Serotonin and Mood: Serotonin influences mood, sleep and appetite; SSRIs raise its levels at synapses. Neuropharmacology: Drugs act on receptors, transporters or enzymes to alter synaptic transmission. Read both side by side and note what each one explains.
What is a common mistake about Serotonin and Mood?
Depression is not just a 'chemical imbalance'.
How should I study Serotonin and Mood step by step?
First, read the summary and write the definition in your own words. Second, read the in-depth section and note any example. Third, compare it with Neuropharmacology and explain the difference aloud. Finally, take the Neuroscience quiz and come back to this page for any question you miss.