*2.1. Both Short-Term and Long-Term EA Stimulation Attenuated CFA Induced Mechanical Allodynia*

Rats were injected with CFA into the surface of the right hindpaw to induce persistent inflammatory pain. The paw withdrawal threshold (PWT) of the rats was significantly decreased after CFA injection, indicative of mechanical allodynia establishment. The pain hypersensitivity was sustained throughout the experiment (*P* < 0.05, Figure 1). With daily EA stimulation for 3 days, 100 Hz EA significantly increased the PWT on days 1 and 3 when compared with the CFA group and sham EA group at the same time points (*P* < 0.05, Figure 1C). With daily EA stimulation for 14 days, 100 Hz EA significantly increased the PWT on days 1, 3, 7, and 14 when compared with the CFA group and sham EA group at the same time point (*P* < 0.05, Figure 1D). Compared with the no acupuncture group (i.e., the CFA only group), sham EA had no significant effect on the PWT.

**Figure 1.** *Cont.*

**Figure 1.** The analgesic effect of 3 days and 14 days 100 Hz electroacupuncture (EA) stimulation on the paw withdrawal threshold (PWT). (**A**) The procedure of short-term (3 days) high frequency EA stimulation experiment. (**B**) The procedure of long-term (14 days) high frequency EA stimulation experiment. (**C**) The analgesic effect of 3 days 100 Hz EA stimulation on the PWT. (**D**) The analgesic effect of 14 days 100 Hz EA stimulation on the PWT. Data are presented as the mean ± SEM, *n* = 9. \* *P* < 0.05, compared with the control group; # *P* < 0.05, compared with the Freund's complete adjuvant (CFA) group; -*P* < 0.05, compared with the CFA + sham EA group.
