Scientists found that enterochromaffin (EC) cells, which are present throughout the digestive system and are important in regulating gut motility, express nasal olfactory receptors (ORs), which trigger serotonin release.
Researchers from the Technical University of Munich and the Ludwig Maximillian University of Munich were investigating whether odorants present in spices, fragrances, cigarettes, detergents, and cosmetics may cause serotonin release, thereby provoking a GI response.
They studied human EC cells isolated from mucosal biopsies by laser microdissection and an EC-derived cell line. The experiments revealed expression of several ORs in the isolated EC cells as well as the cell line. Using digital fluorescence imaging, the team found that activation of the cells with odorants caused elevation of intracellular Ca2+ followed by serotonin release up to 10-fold that of the controls.
The findings suggest that these types of odorants may cause a serotonin-related GI reaction. The effects could be inhibited by known OR antagonists such as methyl isoeugenol or by blocking Ca2+ influx, for example, via Ca2+ channels with nifedipine, a drug used in the treatment of hypertension.