Differential expression of TRPV1 and TRPM8 in the mouse trigeminal ganglion and spinal dorsal root ganglion.

Transient receptor potential (TRP) ion channels, including the thermoreceptor TRP vanilloid 1 (TRPV1) and innocuous warm detector TRP melastatin 8 (TRPM8), are widely expressed on the primary sensory neurons of the trigeminal ganglion (TG) and the dorsal root ganglion (DRG). By performing real-time quantitative PCR and immunostaining, we compared TRPV1 and TRPM8 gene expression and immunostaining in mouse DRG and TG neurons. Both TRPV1 and TRPM8 are widely expressed in the TG and DRG, but in different patterns: TRPV1 has relatively more abundant expression and immunostaining in the DRG, whereas TRPM8 has higher levels in the TG. Double-staining for TRPV1 and TRPM8 revealed very little coexpression in either the TG or the DRG. These results suggest that TRPV1 and TRPM8 are differentially expressed in TG and DRG, and this significant variation may underlie the different temperature sensory properties of the skin and oral cavity.