Mechanism of dorsal root ganglion SERT in electroacupuncture regulation of P2X3 receptor-mediated visceral hypersensitivity in IBS rats

背根神经节SERT参与电针调节P2X3受体介导的IBS大鼠内脏高敏感的机制研究

Objective:To investigate the role of serotonin reuptake transporter(SERT)and P2X3 receptor of dorsal root ganglion(DRG)in regulating visceral hypersensitivity of rats with irritable bowel syndrome(IBS)by electroacupuncture(EA).Methods:Male Sprague-Dawley and SERT^(-/-)rats were subjected to preparing IBS visceral hypersensitivity models with 2,4,6-trinitrobenzene sulfonic acid(TNBS)enema.Three weeks post-modeling,interventions including EA,intrathecal injection,and EA plus intrathecal injection were applied,respectively.Hematoxylin-eosin staining and abdominal withdrawal reflex(AWR)score were used to confirm the successful establishment of the IBS model.AWR score,whole-cell patch clamp technique,and Western blotting assay were used to evaluate the changes in visceral pain sensitivity,electrophysiological properties of DRG neurons,and the expression of DRG P2X3 receptor and SERT in IBS rats.Results:Compared to the model group,the AWR score in the EA group decreased significantly(P<0.05),the resting membrane potential(P<0.05)and the number of action potentials(P<0.05)of DRG neurons reduced,and the baseline intensity increased(P<0.05);additionally,the expression of P2X3 receptor in DRG decreased(P<0.01),and the SERT expression increased(P<0.05).Compared to the P2X3 receptor agonist group,the SERT protein expression in DRG was higher in the EA group.In SERT^(-/-)rats,the P2X3 receptor expression in DRG increased in the EA group compared to the model group(P<0.01).Conclusion:EA modulates the electrophysiological characteristics of intestinal primary sensory neurons by regulating the expression of SERT and P2X3 receptor in DRG of IBS rats.This modulation may contribute to the mechanism by which EA alleviates peripheral sensitization of visceral pain in IBS rats.

目的:探讨背根神经节(DRG)中5-羟色胺重摄取转运体(SERT)、P2X3受体在电针调节肠易激综合征(IBS)大鼠内脏高敏感中的作用。方法:雄性Sprague-Dawley和SERT^(-/-)大鼠,通过三硝基苯磺酸(TNBS)灌肠液灌肠制备IBS内脏高敏感模型。模型制备3周后分别用电针、髓鞘内注射、电针加髓鞘内注射干预。采用苏木素-伊红染色、腹部撤退反射(AWR)评分观察IBS内脏高敏感模型是否制备成功;运用AWR评分、全细胞膜片钳、免疫印迹法检测IBS大鼠内脏痛敏的变化、DRG神经元细胞的电生理特性变化及DRG中P2X3受体、SERT的表达变化。结果:与模型组比较,电针组AWR评分下降(P<0.05);DRG神经元细胞的静息膜电位下降(P<0.05)、动作电位个数减少(P<0.05)、基强度增加(P<0.05);DRG中P2X3受体的表达下降(P<0.01)、SERT的表达升高(P<0.05)。与P2X3受体激动剂组比较,电针组DRG中SERT的蛋白表达升高(P<0.05)。与模型组比较,电针组SERT^(-/-)大鼠DRG中P2X3受体的表达增加(P<0.01)。结论:电针可通过调节IBS内脏痛大鼠DRG中SERT、P2X3受体的表达改变肠道初级感觉神经元的电生理特性;这可能是电针缓解IBS大鼠内脏痛外周敏化的机制之一。