Activity of AM1241 at the tail flick test in naïve rats and in rats treated with nitroglycerin. Data are expressed as percent change (0%) from baseline ± SEM. In naïve rats, DMSO, used as vehicle, did not show significant effect on latency when compared with baseline levels, while AM1241 induced a significant increase of latency 60 minutes after its administration. Rats treated with nitroglycerin (NTG) showed hyperalgesia, demonstrated by the significant reduction in the latency of tail flicking 4 h after its administration when compared with baseline levels. The CT group did not show significant effect on latency when compared with baseline levels. Both doses of AM1241 failed to modify NTG-induced hyperalgesia. *p < 0.05 vs baseline.