Abstract
Transient receptor potential (TRP) non-selective cation channel is involved in various sensory systems. TRP channels that respond to low or high temperatures have been identified in cell bodies of sensory neurons in dorsal root ganlia. Some of these thermo TRP channels have been reported to induce autonomic thermoregulatory responses, and sensations such as cold and hot, leading to behavioral thermoregulation. In the present paper, we state TRP melastatin 8 (TRPM8) channel that is sensitive to low temperature less than 28 oC and menthol (ingredient of mint). In TRPM8 knockout (KO) mice, when cooling stimuli is applied to plantar skin, cold-escape behavior is inhibited, indicating that TRPM8 at plantar skin mediates cooling-induced cold-escape behavior. We showed previously that when menthol is applied to whole body skin of wild type (WT) mice, core temperature is increased by 1-2 oC through activation of heat-gains responses such as shivering and non-shivering thermorgenesis. This indicates that there are pathways from TRPM8-expressing sensory neurons to thermoregulatory effectors for autonomic and behavioral thermoregulation. However, the structure of TRPM8-exressing nerves in the skin is not known. In the present paper, we investigated nerve endings of TRPM8-expressing neurons of mice using anti-TRPM8 antibody, which was produced in out laboratory. We report that TRPM8 is positively stained at free nerve endings in various areas of skin. [J Physiol Sci. 2008;58 Suppl:S9]
