T-type calcium channels, but not Cav3.2, in the peripheral sensory afferents are involved in acute itch in mice

Abstract

T-type calcium channels are prominently expressed in primary nociceptive fibers and well characterized in pain processes. Although itch and pain share many similarities including primary sensory fibers, the function of T-type calcium channels on acute itch has not been explored. We investigated whether T-type calcium channels expressed within primary sensory fibers of mouse skin, especially Ca_v3.2 subtype, involve in chloroquine-, endothelin-1- and histamine-evoked acute itch using pharmacological, neuronal imaging and behavioral analyses. We found that pre-locally blocking three subtypes of T-type calcium channels in the peripheral afferents of skins, yielded an inhibition in acute itch or pain behaviors, while selectively blocking the Ca_v3.2 channel in the skin peripheral afferents only inhibited acute pain but not acute itch. These results suggest that T-type Ca_v3.1 or Ca_v3.3, but not Ca_v3.2 channel, have an important role in acute itch processing, and their distinctive roles in modulating acute itch are worthy of further investigation.

Keywords: Ca(v)3.2; Chloroquine; Endothelin-1; Histamine; Itch; T-type calcium channels.