# 5-HT3 receptor (HTR3A)

Source: https://onco.cc/targets/htr3a/  
OnCo record `htr3a` (Target). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

The serotonin receptor on the gut's vagus nerve endings and in the brainstem vomiting centre that chemotherapy triggers. Ondansetron and palonosetron block it, the foundation of modern anti-sickness treatment.

## Summary

Chemotherapy damages enterochromaffin cells in the gut lining, releasing serotonin that activates 5-HT3 receptors on vagal afferents and in the area postrema to provoke acute vomiting. 5-HT3 antagonists, first ondansetron in 1991 and later granisetron and the long-acting palonosetron, block this pathway and transformed the experience of cisplatin-based and anthracycline-based chemotherapy. They are combined with an NK1 antagonist and dexamethasone for highly emetogenic regimens; constipation, headache and QT prolongation are the main side effects.

## Fields

- Kind: Target
- Last checked: 2026-09-04
- Symbol: HTR3A
- Class: other
- Biology: Ligand-gated ion channel for serotonin on vagal afferents and in the brainstem chemoreceptor trigger zone; blocked by setron antiemetics.
- Where found: Supportive care: prevention of chemotherapy-induced nausea and vomiting

## Sources

- Wikipedia: https://en.wikipedia.org/wiki/5-HT3_receptor
- UniProt P46098: HTR3A: https://www.uniprot.org/uniprotkb/P46098/entry

## Connected records

- targets: [Cannabinoid receptor 1](https://onco.cc/targets/cnr1/), [NK1 receptor (TACR1)](https://onco.cc/targets/tacr1/)
- drugs: [Dolasetron](https://onco.cc/drugs/dolasetron/), [Granisetron](https://onco.cc/drugs/granisetron/), [Ondansetron](https://onco.cc/drugs/ondansetron/), [Palonosetron](https://onco.cc/drugs/palonosetron/)

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JSON: https://onco.cc/api/v1/entities/htr3a.json