Fig. 1

Repeated EA treatment reduced CCI-induced mechanical and thermal hyperalgesia and mirror-image pain in neuropathic pain rats (mean ± SD, n = 12/group). Both mechanical (response time: a, force threshold: b) and thermal paw withdrawal latencies (PWLs) at the ipsilateral (Ipsi., a, c, e) and contralateral (Cont., b, d, f) paws were observed before and every 3 days after chronic constrictive injury (CCI) of the sciatic nerve. Compared with the CCI rats, CCI-decreased mechanical PWLs were significantly increased by EA treatment from the 12th day on (time response: a) and 9th day on (force response: c) after surgery on the Ipsi. side (a, c), and from the 6th day on the Cont. side (b, d); and CCI-decreased thermal PWLs were significantly up-regulated by EA from the 6th day on after surgery on the Ipsi. side (e) and turned to the normal level from the 6th day on after surgery on the Cont. side (f), suggesting a positive effect of EA on chronic neuropathic pain and mirror-image pain. (*P < 0.05, vs the sham group; # P < 0.05, vs the CCI group)