P2X4R在大鼠三叉神经痛维持中的作用:与p38 MAPK/BDNF信号通路的关系

Role of P2X4R in maintenance of trigeminal neuralgia in rats:relationship with p38 MAPK/BDNF signaling pathway

目的评价离子型嘌呤受体4(P2X4R)在大鼠三叉神经痛维持中的作用及与p38丝裂原活化蛋白激酶(p38 MAPK)/脑源性神经营养因子(BDNF)信号通路的关系。方法清洁级健康成年雄性SD大鼠48只,体质量190~230 g,2~3月龄,采用随机数字表法分为4组(n=12):假手术组(S组)、三叉神经痛组(TN组)、三叉神经痛+二甲基亚砜组(TN+DMSO组)和三叉神经痛+P2X4R特异性拮抗剂5-BDBD组(TN+5-BDBD组)。采用三叉神经眶下支慢性缩窄术制备三叉神经痛模型。于造模后3、7、10和14 d时,TN+5-BDBD组鞘内注射5μg/μl 5-BDBD 10μl,TN+DMSO组鞘内注射2%二甲基亚砜10μl。于造模前1 d、造模后1、3、7、10、14和28 d(T_(0~6))时测定面部机械痛阈(MWT)。末次行为学测定结束后,处死大鼠取三叉神经节,采用Western blot法检测P2X4R、p38 MAPK、磷酸化p38 MAPK(p-p38 MAPK)和BDNF的表达,采用ELISA法检测TNF-α、IL-1β和IL-6的含量。结果与S组比较,TN组T1~6时MWT降低,三叉神经节P2X4R、p-p38MAPK和BDNF表达上调,TNF-α、IL-1β和IL-6含量升高(P<0.05);与TN组比较,TN+5-BDBD组T_(3~6)时MWT升高,三叉神经节P2X4R、p-p38 MAPK和BDNF表达下调,TNF-α、IL-1β和IL-6含量降低(P<0.05),TN+DMSO组上述指标差异无统计学意义(P>0.05)。结论P2X4R参与了大鼠三叉神经痛的维持,可能与激活p38 MAPK/BDNF信号通路,增加炎性介质释放有关。

Objective To evaluate the role of P2X4 receptor(P2X4R)in the maintenance of trigeminal neuralgia and the relationship with p38 mitogen-activated protein kinase(p38 MAPK)/brain-derived neurotrophic factor(BDNF)signaling pathway in rats.Methods Forty-eight clean-grade healthy adult male Sprague-Dawley rats,weighing 190-230 g,aged 2-3 months,were divided into 4 groups(n=12 each)using a random number table method:sham operation group(S group),trigeminal neuralgia group(TN group),trigeminal neuralgia+dimethylsulfoxide(DMSO)group(TN+DMSO group),and trigeminal neuralgia+P2X4R specific antagonist 5-BDBD group(TN+5-BDBD group).The model was developed by chronic constriction of the infraorbital nerve.The infraorbital nerve was only exposed without ligation in group S.At 3,7,10 and 14 days after developing the model,5μg/μl 5-BDBD 10μl was intrathecally injected in TN+5-BDBD group,and 2%DMSO 10μl was intrathecally injected in TN+DMSO group.The facial mechanical pain withdrawal threshold(MWT)was measured at 1 day before developing the model and 1,3,7,10,14 and 28 days after developing the model(T0-6).The rats were sacrificed and the trigeminal ganglia were taken for determination of the expression of P2X4R,p38 MAPK,phosphorylated p38 MAPK(p-p38 MAPK)and BDNF(by Western blot)and contents of tumor necrosis factor(TNF)-αand interleukin(IL)-1βand IL-6(by enzyme-linked immunosorbent assay).Results Compared with group S,the MWT was significantly decreased at T1-6,the expression of P2X4R,p-p38 MAPK and BDNF in trigeminal ganglion was up-regulated,and the contents of TNF-α,IL-1βand IL-6 were increased in TN group(P<0.05).Compared with TN group,the MWT was significantly increased at T3-6,and the expression of P2X4R,p-p38 MAPK and BDNF in trigeminal ganglion was down-regulated,and the contents of TNF-α,IL-1βand IL-6 were decreased in TN+5-BDBD group(P<0.05),and no significant change was found in the indexes mentioned above in TN+DMSO group(P>0.05).Conclusions P2X4R is involved in the maintenance of trigeminal neuralgia in rats,which may be related to the activation of p38 MAPK/BDNF signaling pathway and the increase in inflammatory mediator release.