The terpenes alpha-bisabolol and camphene modulate pruritus via an action on Cav3.2 T-type calcium channels.

Abstract

Alpha-bisabolol and camphene have demonstrated analgesic effects in inflammatory pain models by blocking Cav3.2 calcium channels. As the pain pathway overlaps with mechanisms for itch, and because Cav3.2 channels have been associated with itch in our previous work, we aimed to investigate the potential anti-itch effects of these two terpenes. Although both terpenes failed to show anti-pruritogenic properties when dissolved in aqueous PBS, when diluted in Hydroxypropyl-beta-cyclodextrin their bioactivity significantly increased. Both compounds significantly reduced scratching in the histaminergic itch model, whether administered subcutaneously or intraperitoneally. Camphene reduced itching in the non-histaminergic model regardless of the route of administration, whereas alpha-bisabolol did not alleviate chloroquine-induced itching. When tested in Cav3.2-/- mice, neither camphene nor alpha-bisabolol significantly reduced histamine-induced scratching behavior. This suggests that the anti-pruritic actions of these terpenes may involve Cav3.2 block to mitigate itch.