The PAR-1-activating peptide attenuates carrageenan-induced hyperalgesia in rats.

We examined if thrombin or a receptor-activating peptide for protease-activated receptor-1 (PAR-1), a thrombin receptor, could modulate nociception at peripheral levels. Intraplantar administration of PAR-1 activators, thrombin or TFLLR-NH(2), but not its inactive control FTLLR-NH(2) or a PAR-2 activator SLIGRL-NH(2), significantly attenuated the hyperalgesia in rats treated with carrageenan, although they had no effect on nociception in naïve rats. The thrombin-PAR-1 system might thus act to attenuate nociception during inflammatory hyperalgesia.