Objective: To observe the effect of electroacupuncture (EA) at "Tianshu" (ST 25) and "Shangjuxu" (ST 37) on mental state, visceral sensitivity and protein expression of nerve growth factor (NGF), tyrosine kinase receptor A (TrkA) and transient receptor potential vanilloid 1 (TRPV1) of colonic tissue in diarrhea-predominant irritable bowel syndrome (IBS-D) rats, and to explore its possible mechanism on treating IBS-D.
Methods: A total of 36 male SD rats of SPF grade were randomized into a blank group, a model group, an EA group and a western medication group, 9 rats in each group. In the model group, the EA group and the western medication group, IBS-D model was established by enema of dinitrobenzene sulfonic acid (DNBS) combined with chronic restraint stress method. In the EA group, EA was applied at "Tianshu" (ST 25) and "Shangjuxu" (ST 37), with disperse-dense wave, in frequency of 2 Hz/100 Hz, 20 min each time, once a day for 7 days. In the western medication group, pinaverium bromide suspension was given by gavage (15 mg•kg-1•d-1) for 7 days. Before and after model establishment, and after intervention, the body mass, 24 h food intake and fecal water content were observed, the visceral sensitivity was detected by abdominal withdrawal reflex (AWR); after intervention, the mental state was evaluated by elevated plus maze (EPM) test, the protein expression of NGF, TrkA and TRPV1 was detected by immunohistochemistry and Western blot in the 4 groups.
Results: After model establishment, compared with the blank group, the body mass and 24 h food intake were decreased (P<0.05), first systolic latency of AWR was shortened and number of contraction wave of AWR was increased (P<0.05), and fecal water content was increased (P<0.05) in the model group, the EA group and the western medication group. After intervention, compared with the blank group, open arm residence time ratio (OT%) of EPM was decreased (P<0.05) and protein expression of NGF, TrkA, TRPV1 in colonic tissue was increased in the model group (P<0.05); compared with the model group, the body mass and 24 h food intake were increased (P<0.05), first systolic latency of AWR was lengthened and number of contraction wave of AWR was decreased (P<0.05), the fecal water content was decreased (P<0.05), OT% of EPM was increased (P<0.05), and protein expression of NGF, TrkA, TRPV1 in colonic tissue was decreased (P<0.05) in the EA group and the western medication group.
Conclusion: Electroacupuncture at "Tianshu" (ST 25) and "Shangjuxu" (ST 37) can relieve the anxiety and depression-like behaviors in IBS-D rats, down-regulate the protein expression of NGF, TrkA, TRPV1 in colonic tissue, so as to reduce the visceral sensitivity and relieve symptoms.
目的：观察电针“天枢”“上巨虚”对腹泻型肠易激综合征（IBS-D）模型大鼠精神状态、内脏敏感性及结肠组织神经生长因子（NGF）、酪氨酸激酶受体A（TrkA）、瞬时受体电位香草酸亚型1（TRPV1）表达的影响，探讨电针干预IBS-D的可能机制。方法：将36只雄性SPF级SD大鼠随机分为空白组、模型组、电针组和西药组，每组9只。模型组、电针组、西药组采用二硝基苯磺酸（DNBS）灌肠结合慢性束缚应激法建立IBS-D模型。电针组予电针双侧“天枢”“上巨虚”，疏密波，频率2 Hz/100 Hz，每次20 min；西药组给予匹维溴铵混悬液（15 mg•kg-1•d-1）灌胃，均持续7 d。分别于造模前后及干预后观察各组大鼠体质量、24 h进食量和粪便含水量，采用腹壁回撤反射（AWR）法检测大鼠内脏敏感性；干预后，采用高架十字迷宫实验评估大鼠精神状态，免疫组化法、Western blot法检测结肠组织NGF、TrkA、TRPV1蛋白表达。结果：造模后，与空白组比较，模型组、电针组、西药组大鼠体质量及24 h进食量减少（P<0.05），AWR初次收缩潜伏期缩短、收缩波个数增多（P<0.05），粪便含水量增加（P<0.05）。干预后，与空白组比较，模型组高架十字迷宫实验开放臂停留时间比例（OT%）值降低（P<0.05），结肠组织NGF、TrkA、TRPV1蛋白表达升高（P<0.05）；与模型组比较，电针组和西药组大鼠体质量及24 h进食量增加（P<0.05），AWR初次收缩潜伏期延长、收缩波个数减少（P<0.05），粪便含水量减少（P<0.05），OT%值升高（P<0.05），结肠组织NGF、TrkA、TRPV1蛋白表达降低（P<0.05）。结论：电针“天枢”“上巨虚”可缓解IBS-D模型大鼠焦虑抑郁状态，下调结肠组织NGF、TrkA、TRPV1表达，从而减轻其内脏敏感性，缓解IBS-D症状。.
Keywords: diarrhea-predominant irritable bowel syndrome; electroacupuncture; nerve growth factor (NGF); transient receptor potential vanilloid 1 (TRPV1); tyrosine kinase receptor A (TrkA); visceral sensitivity.