电针“天枢”穴对感染后肠易激综合征内脏高敏感模型大鼠结肠肥大细胞活化和P物质的影响

Electroacupuncture of “Tianshu”(ST 25) Suppresses Visceral Pain Possibly by Down-regulating Mast Cell Activation,and Tryptase and SP Expression in Rats with Post-infectious Irritable Bowel Syndrome

目的:探讨电针"天枢"穴治疗感染后肠易激综合征(PI-IBS)内脏高敏感大鼠的效应机制。方法:Wistar雌性大鼠随机分为对照组、模型组和电针组,每组各15只。利用三硝基苯磺酸(TNBS)灌肠诱导PI-IBS内脏高敏感模型。电针组电针双侧"天枢"穴,每次30 min,每日1次,连续14d。腹部回缩反射(AWR)检测内脏疼痛感觉阈值,HE染色法观察结肠组织病理形态,甲苯胺蓝染色法观察结肠组织肥大细胞(MC)形态和数目,免疫组化法测定结肠组织类胰蛋白酶、P物质(SP)表达情况。结果:与对照组比较,模型组大鼠腹部抬起时球囊容量阈值明显降低(P<0.05);黏膜下层和肠固有腺间有少量淋巴细胞和浆细胞浸润,结肠组织MC数目增多(P<0.05),呈活化脱颗粒状态;结肠组织类胰蛋白酶、SP表达均升高(P<0.05)。与模型组比较,电针治疗后大鼠腹部抬起时球囊容量阈值升高(P<0.05);结肠MC数目降低(P<0.05),脱颗粒程度不明显;结肠组织类胰蛋白酶、SP表达均降低(P<0.05)。结论:电针"天枢"穴可能通过改善结肠MC活化状态、降低SP表达,改善大鼠内脏高敏感状态。

Objective To observe the effect of electroacupuncture（EA）at＂Tianshu＂（ST 25）on visceral pain and colonic mast cell（MCs）number and tryptase and SP expression in post-infectious irritable bowel syndrome（PI-IBS）rats,so as to reveal its mechanisms underlying improvement of PI-IBS.Methods Forty-five female Wistar rats were randomly divided into control,model and EA groups（15 rats/group,3 rats/group used for H.E.staining,and 12 rats/group for immunohistochemistry）.The PI-IBS model was established by intra-anal injection of mixed liquor of 50% ethyl alcohol and trinitro-benzene-sulfonic acid（TNBS）.EA（2 Hz/15 Hz,0.5-1.0 mA）was applied to bilateral＂Tianshu＂（ST 25）for 30 min,once every day for 14 days.The visceral pain was measured by abdominal withdrawal reflex（AWR）,for which the rectal implanted air balloon was dilated by infusion of normal saline.The histopathological changes of the colon tissue were observed after H.E.staining,and the colonic MCs were displayed by Toluidine blue staining.The expression of tryptase and SP proteins in the colon specimens were detected by immunohistochemistry.Results The AWR threshold was significantly lowered in the model group relevant to the control group（P〈0.05）and considerably increased after EA intervention in comparison with the model group（P〈0.05）.The number of MCs and the expression levels of colonic tryptase and SP proteins in the colon tissues were significantly higher in the model group than in the control group（P〈0.05）,and obviously lower after EA intervention in the EA group than in the model group（P〈0.05）.Conclusion EA of＂Tianshu＂（ST 25）can inhibit visceral pain in PI-IBS rats,which may be associated with its effects in activating MCs and down-regulating the expression of tryptase and SP proteins in the colonic tissues.