Abstract: Objective The study was designed to investigate the relation of phospho-p38 mitogen-activated protein kinase(p-p38MAPK) and purine 2X3(P2X3) receptors in the dorsal root ganglion of inflammatory pain induced by complete freund's adjuvant (CFA) in rats. Methods Seventy-two male SD rats weighing 200 g-250 g were randomly divided into six groups(n=12):Sham+dimethyl sulfoxide(DMSO) group, CFA+DMSO group, Sham+P2X3 inhibitor A-317491(Sham+A) group, CFA+A-317491(CFA+A) group, Sham+p38 mitogen-activated protein kinase(p38MAPK) inhibitor SB203580(Sham+SB) group and CFA+SB203580(CFA+SB) group, and each of them was further divided into two subgroups respectively: the pain behavior groups(n=6) and the Western blot groups(n=6). Pain behavior was assessed by paw thermal withdrawal latency(TWL) at 1 d before and 1, 2, 4 d after CFA. Rats in the Western blot groups were sacrificed 2 d after CFA. Results Compared with their preoperative values and corresponding values in Sham+DMSO group, the TWL values in CFA+DMSO group, CFA+A group, CFA+SB significantly decreased [the TWL values of postoperative 2 d were(16.3±1.1), (5.0±0.7), (12.6±1.5), (10.7±1.6) s]. The TWL of CFA+A group and CFA+SB group were significantly increased than CFA+DMSO group's(P<0.05). Two days after CFA, the expression of p-p38MAPK and P2X3 were significantly increased(P<0.05). After application of SB203580, the expression of p-p38MAPK and P2X3 decreased significantly(P<0.05). After application of A-317491, the expression of P2X3 decreased significantly, while no significant difference was showed in the expression of p-p38MAPK(P>0.05). Conclusions P2X3 receptor is upregulated through activation of the p38MAPK pathway after inflammation.
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