Fig. 3.
Local application of nerve blockers during the initial stage of neuropathic pain blocks the subsequent development of neuropathic pain in spared nerve injury (SNI) model. Rats with SNI were tested for thermal pain (a, b, e, f) and mechanical pain (c, d, g, h). Both thermal hyperalgesia and mechanical allodynia lasted well over 60 days. Both difference scores and absolute pain thresholds are presented for each experiment, using the same format as in Fig. 2. Nerve blockade at the initial stage of neuropathic pain (shaded areas) by 200 mg bupivacaine (a–d) or by TTX (e–h) inhibited the development of neuropathic pain. For all data shown, the groups with nerve blockade (N = 12–13) differed significantly from the group with SNI only (N = 6; one-way ANOVA with Dunnett’s post-test, P<0.01). The SNI plus saline group (N = 6) did not differ significantly from SNI only.