Capsaicin Is a Negative Allosteric Modulator of the 5-HT3 Receptor

Eslam El Nebrisi, Tatiana Prytkova, Dietrich Ernst Lorke, Luke Howarth, Asma Hassan Alzaabi, Keun Hang Susan Yang, Frank C. Howarth, Murat Oz

Research output: Contribution to journalArticlepeer-review

8 Citations (Scopus)


In this study, effects of capsaicin, an active ingredient of the capsicum plant, were investigated on human 5-hydroxytryptamine type 3 (5-HT3) receptors. Capsaicin reversibly inhibited serotonin (5-HT)-induced currents recorded by two-electrode voltage clamp method in Xenopus oocytes. The inhibition was time- and concentration-dependent with an IC50 = 62 μM. The effect of capsaicin was not altered in the presence of capsazepine, and by intracellular BAPTA injections or trans-membrane potential changes. In radio-ligand binding studies, capsaicin did not change the specific binding of the 5-HT3 antagonist [3H]GR65630, indicating that it is a noncompetitive inhibitor of 5-HT3 receptor. In HEK-293 cells, capsaicin inhibited 5-HT3 receptor induced aequorin luminescence with an IC50 of 54 µM and inhibition was not reversed by increasing concentrations of 5-HT. In conclusion, the results indicate that capsaicin acts as a negative allosteric modulator of human 5-HT3 receptors.

Original languageEnglish
Article number1274
JournalFrontiers in Pharmacology
Publication statusPublished - Aug 31 2020


  • 5-HT receptor
  • HEK-293 cells
  • Xenopus oocytes
  • allosteric modulator
  • capsaicin
  • docking
  • serotonin

ASJC Scopus subject areas

  • Pharmacology
  • Pharmacology (medical)


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