Effect of cyclooxygenase and nitric oxide synthase inhibitors on streptozotocin-induced hyperalgesia in rats

We examined a possible involvement of cyclooxygenase (COX) and nitric oxide synthase (NOS) products in hyperalgesia occurring during streptozotocin (STZ)-induced diabetes. Indomethacin and celecoxib were used as relatively selective inhibitors of COX-1 and COX-2, respectively. NOS inhibitors included: non-specific inhibitor N(G)-nitro-L-arginine and L-N(6)-(1-iminoethyl)lysine preferentially acting on inducible NOS (iNOS) as well as 7-nitroindazole relatively specific inhibitor neuronal NOS (nNOS). The above-mentioned agents, except 7-nitroindazole, suppressed hyperalgesia occurring after administration of STZ. The results of the study suggest participation of COX-1, COX-2 and iNOS, but not nNOS, in transmission of pain stimuli in STZ-induced diabetic hyperalgesia.