Effects of acid sensing ion channels inhibitor amiloride on pain behavior in a rat model of post-incision pain

Abstract

Objective To explore the effects and underlying mechanisms of acid sensing ion channels(ASICs) on pain behavior in a rat model of post-incision pain. Methods Fifty-eight adult male Sprague Dawley rats were used in this study, four rats were used for immunofluorescence test, thirty rats were employed for pain behavior test, and twenty-four rats were used for Western blot. Rats used for pain behavior test and Western blot were randomly divided into 3 groups: control group (C group), incision pain model group (I group) and amiloride group (A group). Plantar skin of rats in A group were infiltrated with 20 μl(200 μg)amiloride solution. Paw withdrawal mechanical threshold(PWMT) and paw withdrawal thermal latency(PWTL) of all rats in pain behavior test was tested at 24 h preoperative, 2 h, 4 h, 8 h, 12 h, 24 h postoperative. Western blot was tested at 4 h postoperative. Results Immunofluorescence test displayed ASIC3 was expressed in plantar skin of all rats. The basal level of PWMT and PWTL of all rats in three groups was C group((23.15±5.10)g, (11.32±1.21)s), I group((23.26±5.69)g, (11.75±2.01)s), A group((23.63±4.96)g, (11.47±1.96)s) respectively, which was no significantly difference (P>0.05). PWMT and PWTL of I group and A group was significantly lower than that of C group at all time points postoperative (P < 0.05); PWMT and PWTL of A group was at 2 h((13.75±3.25)g, (9.96±1.32)s), 4 h((14.05±3.75)g, (9.17±2.11)s), 8 h((9.75±2.74)g, (8.11±1.22)s) postoperative, which was significantly higher than that of I group(P<0.05). Compared with that of C group, the level of pERK1/2 expression was significantly increased in I group at 4 h postoperative (P<0.05), which could be inhibited by amiloride local infiltration (P<0.05). Conclusion ASIC3 can mediate incision pain in a rat model of post-incision pain, through pERK1/2 signaling pathway, which can be inhibited by amiloride. Key words: Pain; Post-incision pain; Acid sensing ion channels; Amiloride