Fig. 2.
Blockade of the dorsal reticular nucleus with lidocaine fully reversed mechanical and thermal hypersensitivity induced by chronic morphine. The dorsal reticular nucleus was injected with lidocaine or saline 7 days after the implantation of saline- or morphine-minipumps. The von Frey (A and C) and hot-plate (B and D) tests, which evaluate mechanical and thermal sensitivity, respectively, were performed before and 30 min after the injection of lidocaine (+Lidocaine) or saline (+Saline). The interactions between groups and time are presented at the bottom of the x axis. The injection of saline produced no effects in the von Frey (F1,10 = 0.002, P = 0.965; C) and hot plate (F1,10 =1.2, P = 0.303; D) tests. Data are presented as mean ± SD (Saline-infused animals: lidocaine n = 5, saline n = 6; Morphine-infused animals: lidocaine n = 6, saline n = 6). ***P < 0.001.