Interleukin-1 beta induced-desArg9bradykinin-mediated thermal hyperalgesia in the rat

The induction of desArg9Bk-mediated thermal hyperalgesia has been studied in the rat. Intraplantar injections of interleukin-1 beta, (IL-1 beta, 1-100 Units, U) produced a 30-40% decrease in withdrawal latency to noxious heat which lasted for up to 24 hr in the treated paw. IL-1 beta-induced thermal hyperalgesia was also present in the contralateral paw for up to 1 hr following IL-1 beta injection. Intraplantar tumour necrosis factor-alpha (TNF alpha, 500 U) also reduced the withdrawal latency in the u.v.-treated paw with recovery by 18 hr but with no contralateral hyperalgesia. Forty-eight hr after IL-1 beta but not after TNF alpha administration, desArg9Bk (10 nmol/kg i.v.) reduced the withdrawal latency in both the ipsi- and contra-lateral paws by 30-49%. In naive animals, desArg9Bk was without effect. These data suggest that, in the rat, IL-1 beta but not TNF alpha can lead to the induction of bradykinin B1 receptors mediating thermal hyperalgesia.