Pruritogenic activity of prostaglandin E2.

The itch and erythematous responses induced by intradermal injection of histamine and PGE2 were studied in human skin. Both compounds produced a sensation of itch. The histamine-elicited flare reached a maximum in 3 min and had disappeared after 1 hours. PGE2 induced a similar flare reaction initially, but it was gradually replaced by a smaller, dusky and well delimited erythema. The itch and the flare-like erythema induced by either histamine or PGE2 were alleviated when the subjects were pretreated with the antihistaminic drug chlorcyclizine, thus indicating that at least part of the PGE2 response may be mediated via histamine release. However, when given combined in a mixture, histamine and PGE2 elicited itch of longer duration and flare of larger area than could be accounted for by simple additive histamine effects. Thus, PGE2 seems to potentiate the itch and flare responses induced by histamine in human skin.