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. 2023 Apr 7;164(9):1965–1975. doi: 10.1097/j.pain.0000000000002892

Figure 1.

Figure 1.

EA treatment increased the content of β-END in inflammatory tissues and relieved pain. (A) Experimental procedure timeline of observation of pain and local inflammatory reaction after intramuscular injection of CFA. N = 6 male and 6 female Wistar rats per group, total of 9 groups: control, day 1, day 3, day5, day 7, day 9, day 11, day 13, and day15. Injections were given intramuscularly. (B) A schematic illustration of behavioral testing. Changes in weight-bearing difference (C) and Interleukin- 6 (IL-6) levels in inflammatory tissues (D) measured at 15 days after CFA injection, *P < 0.05 vs control group, #P < 0.05 vs day 1. (E) Experimental procedure timeline of EA treatment. N = 6 male and 6 female Wistar rats per group, total of 4 groups: control, CFA, EA, and Anti-End + EA (antibody concentration: 8 mg/mL, 110 µL). (F) Weight-bearing difference was tested on day 6 after CFA injection in the indicated groups, *P < 0.05 vs control group, #P < 0.05 vs CFA group, &P < 0.05 vs EA group. β-END levels in the tissues (G) and plasma (H) were measured on day 6 after CFA injection and EA treatment, *P < 0.05 vs control group, #P < 0.05 vs CFA group. All data are shown as mean ± SEM; statistical analyses were performed using one-way ANOVA followed by the Tukey honestly significant difference (Tukey HSD) test. ANOVA, analysis of variance; β-END, β-endorphins; CFA, complete Frester adjuvant; EA, electroacupuncture.