抄録
It is reported that thermosensitive-TRP channels (thermo-TRPs) are sensitive to a wide range of temperatures and involved in nociception in terminals of dorsal root ganglia (DRG) neurons. Especially, TRPV1, TRPV2, TRPA1 and TRPM8 are expressed in adult mouse DRG neurons to exert nociception and/or thermosensation. In general, it is well known that ion channels have distinct roles between embryonic and adult stages. For example, voltage-gated potassium channels regulate cell proliferations, cell migrations or axon extensions during neural development. Analogous with these observations, the thermo-TRPs also might have unexpected specific roles in embryonic neurons compared with those in adult stage. Interestingly, no investigation has been performed to identify when the thermo-TRPs were expressed in developing DRG by focusing on their specific roles in the embryonic stages. Identifications of expression timing of the channels are necessary to clarify the specific roles of the thermo-TRPs in embryo. Therefore, we examined the expression profiles of TRPV1, TRPV2, TRPA1 and TRPM8 in developing mouse DRG and spinal cord by RT-PCR, in situ hybridization, Western blotting, immunohistochemistry and calcium imaging. Surprisingly, the expressions of those thermo-TRPs in DRG were already observed in early embryonic stages, and some of them were observed in spinal cord as well, suggesting that those channels, might have specific roles in the embryonic stages. [J Physiol Sci. 2007;57 Suppl:S221]
