过表达P2X4受体介导三叉神经痛的实验研究

Experimental Study on Overexpression of P2X4 Receptors Mediating Trigeminal Neuralgia

目的:本课题组前期发现,P2X4受体可能通过调控脑源性神经生长因子(brain-derived neurotrophic factor,BDNF)表达,进而介导三叉神经痛(trigeminal neural,TN)分子机制。为此,在TN大鼠模型中转染过表达P2X4受体,进行验证。方法:以结扎框下神经慢性损伤法建立TN大鼠模型,P2X4受体过表达质粒舌下静脉转染至TN大鼠中,以面部痛敏阈检测仪、荧光定量PCR、间接免疫荧光、Western blot和ELISA法检测大鼠三叉神经脊束核(spinal trigeminal nucleus,STN)和三叉神经节(trigeminal ganglia,TG)部位疼痛阈值,P2X4、BDNF和TrkB转录水平,P2X4和BDNF定位情况,P2X4、BDNF、TrkB蛋白表达和ERK磷酸化水平,炎性因子白细胞介素-1β(interleukin-1β,IL-1β)和肿瘤坏死因子-α(tumor necrosis factor-α,TNF-α)表达。结果:过表达P2X4受体组大鼠疼痛阈值降低,STN和TG部位P2X4、BDNF受体和TrkB转录水平升高(P<0.01),STN中BDNF受体与小胶质标志物OX42共定位、TG中P2X4与胶质纤维酸性蛋白(glial fibrillary acidic protein,GFAP)共定位,STN和TG部位ERK磷酸化水平升高(P<0.01),大鼠血清中IL-1β和TNF-α表达水平升高(P<0.05)。结论:过表达P2X4受体降低大鼠疼痛阈值,表明P2X4离子参与了TN疼痛通路,其机制为P2X4调控了BDNF/ERK通路,增强了ERK磷酸化和炎性因子IL-1β和TNF-α表达。

Objective:To validate whether P2X4 receptors mediate the molecular mechanism of trigeminal neuralgia(TN)by regulating the expression of brain-derived neurotrophic factor(BDNF)through transfecting overexpressed P2X4 receptors in a TN rat model.Methods:The P2X4 receptor overexpression plasmid was transfected into the sublingual vein of TN rats.The facial pain threshold assay,quantitative fluorescence PCR,indirect immunofluorescence,protein blotting,and ELISA were used to detect the pain thresholds in rat spinal trigeminal nucleus(STN)and trigeminal ganglia(TG),the transcript levels of P2X4,BDNF,and TrkB,the localization of P2X4 and BDNF,the protein expression of P2X4,BDNF,and TrkB,the phosphorylation levels of ERK,and the expressions of inflammatory factors interleukin-1β(IL-1β)and tumor necrosis factor-α(TNF-α).Results:In the P2X4 receptor overexpression group,pain thresholds were reduced,transcript levels of P2X4,BDNF receptor,and TrkB were increased in STN and TG sites(P<0.01),BDNF receptor was co-localized with microglial marker OX42 in STN,P2X4 was co-localized with glial fibrillary acidic protein(GFAP)in TG,ERK phosphorylation was increased in STN and TG sites(P<0.01),and IL-1βand TNF-αexpression levels were increased in serum(P<0.01).Conclusion:Overexpression of P2X4 receptors decreased pain thresholds in rats,suggesting that P2X4 ions are involved in the TN pain pathway by the mechanism that P2X4 regulates the BDNF/ERK pathway,and enhances ERK phosphorylation and expression of inflammatory factors IL-1βand TNF-α.