INTERLEUKIN-1-BETA ENHANCES CAPSAICIN-INDUCED NEUROGENIC VASODILATATION IN THE RAT SKIN

1 This study examined the effect of interleukin-1 beta (IL-1 beta) on the capsaicin-induced increase in cutaneous blood flow of anaesthetize d rats as measured by laser Doppler flowmetry. 2 The substances were a dministered by intraplantar subcutaneous injection of 10 mu l-volumes, saline being injected into one hindpaw and IL-I beta into the other. 3 IL-1 beta (0.5-500 pg) was without effect on blood how on its own bu t dose-dependently enhanced the hyperaemic response to intraplantar ca psaicin (0.3 mu g) up to 180% (P<0.05) of the response seen in saline- treated paws. 4 Il-1 beta-(163-171), a fragment devoid of proinflammat ory activity, failed to enhance capsaicin-induced hyperaemia when give n at a dose of 50 pg. 5 Indomethacin (10 mg kg(-1), i.p.) did not alte r the capsaicin-induced vasodilatation but prevented IL-1 beta (50 pg) from augmenting the hyperaemic response to capsaicin. 6 The hyperaemi a evoked by intraplantar calcitonin gene-related peptide (0.038-3.8 ng ) was not altered by IL-1 beta (50 pg). 7 These data indicate that IL- I beta enhances the cutaneous hyperaemic response to afferent nerve st imulation with capsaicin in a prostaglandin-dependent manner. This pro inflammatory action of the cytokine appears to arise from sensitizatio n of afferent nerve endings.