Fig. 4

Improvement of mechanical allodynia after PSL by peripheral nicotinic acetylcholine receptor (nAChR) agonists. Mice were subject to PSL or sham surgery, and TC-2559 (20 nmol), sazetidine A (0.2–20 nmol), and DHβE (40 nmol) were p.n. administered four times according to the indicated schedules. The 50% paw withdrawal mechanical threshold was assessed by the up–down method using the von Frey test. a Attenuation of PSL-induced mechanical allodynia in the ipsilateral side by TC-2559 (days 0, 1, 2, and 3) are shown. Effects of TC-2559 were antagonized by the co-administration of DHβE. b There was no significant difference in the contralateral side in all groups. c Suppressive effects of TC-2559 and sazetidine A (days 0, 1, 2, and 3) on PSL-induced mechanical allodynia on day 7 in the ipsilateral side. d Improvement of PSL-induced mechanical allodynia on day 14 in the ipsilateral side by TC-2559 and sazetidine A (days 7, 8, 9, and 10) are shown. e Relief of PSL-induced mechanical allodynia on day 28 in the ipsilateral side by TC-2559 (days 21, 22, 23, and 24) are shown. Data are presented as the mean ± SEM; n = 5–11. ***P<0.001, **P<0.01 versus sham. ^##P < 0.01, **P<0.01^#P < 0.05 versus PSL/Veh, ^$$P<0.01 versus PSL/TC-2559