Immunohistochemical detection of capsaicin receptors in taste cells of human circumvallate papillae

We examined co-localization of the vanilloid receptor subtype 1 (VR1) with sweet (T1R2, T1R3) or bitter (T2R6) receptors in human circumvallate taste cells using double-fluorescence immunohistochemistry. All the T1R2-, T1R3-, or T2R6-immunoreactive cells observed in the circumvallate co-exhibited VR1-immunoreactivity. Many of VR1-immunoreactive cells exhibited α-gustducin immunoreactivity as well. Results support the idea that capsaicin may interact with the transduction pathways of sweet and bitter taste stimuli in human, possibly, in mediation of its receptor VR1 located in taste cells. Additionally, it is suggested that α-gustducin may play a role in the tentative modulatory function of capsaicin in sweet and bitter transductions.