Fig. 4.

Male Sprague Dawley rats received bilateral surgical lesions of the DLF or sham DLF surgery at T₈. After 7 d, the rats were subjected to either L₅/L₆ SNL or sham surgery. Paw-withdrawal thresholds to light tactile stimuli (A) and to noxious radiant heat (B) were determined before spinal surgery before SNL (BNL) and daily for 14 d after SNL or sham surgery. Tactile hypersensitivity (A) and thermal hyperalgesia (B) were evident in all groups with SNL during the initial 4 d of testing, as indicated by the significant decreases in behavioral responses. However, the rats that received both L₅/L₆ SNL and lesions of the DLF demonstrated a clear reversal of SNL-induced threshold changes commencing at postsurgery days 4–5. *p ≤ 0.05 compared with premicroinjection values. N, Naive.