Odontoblast TRP Channels and Thermo/Mechanical Transmission

Abstract

Odontoblasts function as mechanosensory receptors because of the expression of mechanosensitive channels in these cells. However, it is unclear if odontoblasts direct the signal transmission evoked by heat/cold or osmotic changes. This study investigated the effects of heat/cold or osmotic changes on calcium signaling and the functional expression of the thermo/mechanosensitive transient receptor potential (TRP) channels in primary cultured mouse odontoblastic cells, with the use of RT-PCR, fluorometric calcium imaging, and electrophysiology. TRPV1, TRPV2, TRPV3, TRPV4, and TRPM3 mRNA was expressed, but TRPM8 and TRPA1 mRNA was not. The receptor-specific stimulation of TRPV1-3 (heat-sensing receptors) and TRPV4/ TRPM3 (mechanic receptors) caused increases in the intracellular calcium concentration. Moreover, the channel activities of TRPV1-4 and TRPM3 were confirmed by a whole-cell patch-clamp technique. These results suggest that primary cultured mouse odontoblasts express heat/mechanosensitive TRP channels and play a role in the underlying mechanisms of thermo/mechanosensitive sensory transmission.