Fig. 1

Perioperative SD prolongs postsurgical pain. a Design of behavior experiments. Baseline responses were measured before all interventions. SD (6 h per day) began 3 days before and ended 3 days after surgery. Paw withdrawal threshold (mechanical pain) and paw withdrawal latency (thermal pain) were measured 3 days before surgery and for 15 days after surgery. b, c Paw withdrawal threshold and paw withdrawal latency of rats in the sham, sham+SD, incision, and incision+SD groups (5 to 10 rats per group). Two-way ANOVA followed by a post hoc Tukey test: F (3, 242) = 82.12 for mechanical pain, F (3, 269) = 42.62 for thermal pain; *p < 0.05, **p < 0.01 for the incision group vs. the incision+SD group at each time point. d, e Paw withdrawal threshold and paw withdrawal latency of contralateral (control paws) in the same four groups (5 rats per group). Two-way ANOVA followed by a post hoc Tukey test: F (3, 144) = 0.9032 for mechanical pain, F (3, 144) = 4.895 for thermal pain