Serotonin
Start with the big picture
Serotonin is synthesized from tryptophan and stored in enterochromaffin cells, platelets, and CNS raphe nuclei; platelets take it up rather than synthesize it. MAO-A inactivates serotonin to 5-HIAA, whose urinary measurement is used in carcinoid tumor diagnosis. Most 5-HT receptors are GPCRs, while 5-HT3 is a ligand-gated cation channel. Receptor activity helps explain effects on vascular tone, gastrointestinal motility and secretion, mood, migraine, and emesis. The lesson also introduces medicines that act on serotonin receptors or alter serotonin levels, linking these actions to therapeutic uses and risks. In particular, combinations or agents that increase serotonin can contribute to serotonin syndrome, while selected treatments are used for its symptoms and for carcinoid-related effects.
What you'll learn
- Outline serotonin synthesis, storage sites, and MAO-A metabolism.
- Distinguish 5-HT3 signaling from the other serotonin receptor families.
- Relate serotonin receptor activity to vascular, gastrointestinal, and CNS effects.
- Connect selected serotonin agonists and antagonists with their clinical uses.
- Recognize serotonin syndrome features and the role of urinary 5-HIAA in carcinoid diagnosis.
Continue your study
Work through the complete notes and reinforce the topic with the study tools available in the full lesson.
