Application of Vapor Phase Stimulation Method for Screening of Human Odorant Receptors Responding to Cinnamaldehyde

Abstract

Flavors consist of a combination of various odor molecules. Animals sense flavor through the responses of multiple odorant receptors (ORs). Previously, we developed a vapor phase stimulation method for the functional analysis of ORs. In this method, odor molecules are supplied through the vapor phase to cells expressing ORs. In the mammalian odorant sensing system, odor components are transmitted through air, dissolve in nasal mucus covering olfactory sensory neuron (OSN) cells, and then stimulate ORs. Therefore, the vapor phase stimulation method mimics the authentic olfactory response. We tested this method to identify human ORs that respond to cinnamaldehyde, the main component of cinnamon flavor, as a practical model fragrance. Although there is a lag time required for the dissolution of odor in the buffer, the vapor phase activation method gave almost the same results as the liquid phase activation method. Interestingly, a human OR responded to cinnamaldehyde only in vapor phase activation. The method also worked well with the flavor from cinnamon powder.