Fig. 4

The effect of NE and ZD 7288 on hyperalgesia in CM rats. A and B The mechanical pain thresholds of the periorbital region and hindpaw in the CM group were substantially lower than those in the Sham group, and there was no obvious difference between the CM and CM + Vehicle groups. Compared to the CM + Vehicle group, the mechanical pain thresholds of the periorbital region and hindpaw in the CM + NE (36 μg) and CM + ZD 7288 (5 μg) groups were both profoundly elevated. The mechanical pain thresholds of the periorbital region and hindpaw did not show substantial differences among the CM + Vehicle, CM + NE (3.6 μg), and CM + ZD 7288 (0.5 μg) groups. (n = 6/group, **p < 0.01, N, S, not significant). C and D. No substantial difference was found in the mechanical pain thresholds of the periorbital region and hindpaw among the Sham, Sham + Vehicle, Sham + NE (36 μg), and Sham + ZD 7288 (5 μg) groups. (n = 6/group, N, S, not significant)