切口疼痛大鼠背根神经节细胞内P2X_3受体及nNOS表达水平的变化

目的观察趾部切口疼痛大鼠背根神经节细胞内P2X3受体及一氧化氮合酶(nNOS)表达水平的变化。方法健康雄性SD大鼠24只,体质量200～220 g,随机分C组、S组及A组各8只。根据Brennan法建立大鼠左后趾部切口疼痛模型,A组大鼠切口疼痛模型建立后30 min,左后足底皮下注射P2X3受体特异性拮抗剂TNP-ATP 200 nmol,C组及S组注射等容量生理盐水。采用累积疼痛评分法,评定注药后1 h内大鼠疼痛行为变化。注药2h后,采用免疫组化法检测背根神经节P2X3受体及nNOS表达水平的变化。结果 S组和A组累积疼痛评分均高于C组(P均<0.05),A组累积疼痛评分低于S组(P<0.05);S组和A组P2X3受体及nNOS表达水平均高于C组(P均<0.05),A组P2X3受体及nNOS表达水平低于S组(P均<0.05)。结论背根神经节P2X3受体在急性疼痛信号传导中起重要作用,其机制可能与增加背根神经节nNOS的表达有关。

Change of P2X3 receptor and nNOS expression in dorsal root ganglion of rats with incisional pain

Objective It is to observe changes of P2X3 receptor and nNOS expression in dorsal root ganglion of rats with incisional pain.Methods Twenty-four healthy male SD rats which weight was 200~220 g were randomly divided into group C,group S and group A,8 rats in each group.An incision of 1cm long was made in plantar region of the left hind paw according to the methods of Brennan.P2X3 antagonis trinitrophenol ATP(TNP-ATP) 200 nmol was injected into the plantar surface of the left hind paw 30 min after plantar incision was made in group A,equal volume of normal saline was applied in group C and group S.Pain behaviors were assessed using cumulative pain score for 1 h after injection.The expression of P2X3 receptor and nNOS in dorsal root ganglion was measured by immunohistochemistry.Results The cumulative pain scores in group S and group A were significantly higher than that in group C(P<0.05),the cumulative pain scores in group A were significantly lower than that in group S(P<0.05).The expression of P2X3 receptor and nNOS in dorsal root ganglion in group S and group A were significantly higher than that in group C(P<0.05),the expression of P2X3 receptor and nNOS in dorsal root ganglion in group A were significantly lower than that in group S(P<0.05).Conclusion The pain signal transmission is mediated by P2X3 receptor in model of rat plantar incision probably through regulating nNOS expression in dorsal root ganglion.