电针足三里对功能性消化不良模型大鼠内脏高敏感性的影响

Effects of electroacupuncture at Zusanli acupoint on visceral hypersensitivity in rats with functional dyspepsia

背景:功能性消化不良发病机制复杂,内脏高敏感性是其最主要的病理机制之一,但从内脏高敏感性机制层面论证电针治疗功能性消化不良的研究报道较少。目的:探讨电针足三里调节功能性消化不良大鼠内脏高敏感性的效应及其可能机制。方法:将24只雄性7 d龄SD乳鼠随机分为空白组、模型组、电针组,每组8只,后2组采用多因素应激干预法(碘乙酰胺灌胃+不规则喂养+改良郭氏夹尾刺激法)复制功能性消化不良内脏高敏感性大鼠模型,大鼠8周龄即进行电针干预。电针组给予针刺大鼠双侧后肢足三里穴7-10 mm,连接韩式穴位神经刺激仪,参数设置为疏密波,频率2/100 Hz,强度1 mA,每次电针干预20 min,1次/d,每周连续5 d后休息2 d,共2周。计算各组大鼠不同阶段平均体质量,采用足底机械痛阈值反映各组大鼠内脏敏感性,ELISA法检测各组大鼠血清和胃底黏膜组织5-羟色胺表达水平,实时荧光定量PCR法检测各组大鼠胃底黏膜组织环核苷酸直接激活的交换蛋白1、机械敏感性离子通道蛋白PIEZO2mRNA表达水平。结果与结论:(1)与空白组相比,模型组大鼠平均体质量、足底机械痛阈值均显著降低,血清和胃底黏膜组织5-羟色胺水平升高,差异有非常显著性意义(P均<0.01);胃底黏膜组织环核苷酸直接激活的交换蛋白1、PIEZO2 mRNA表达水平升高(P均<0.01);(2)与模型组相比,电针组大鼠干预7,14 d后的平均体质量、足底机械痛阈值均升高,差异有显著性意义(P <0.05,<0.01),血清和胃底黏膜组织5-羟色胺水平及胃底黏膜组织环核苷酸直接激活的交换蛋白1、PIEZO2 mRNA水平均降低(P均<0.01);(3)提示电针足三里可以显著改善功能性消化不良大鼠内脏高敏感性,其作用机制可能与调节肠嗜铬细胞5-羟色胺释放及环核苷酸直接激活的交换蛋白1、PIEZO2表达有关。

BACKGROUND: The pathogenesis of functional dyspepsia is complex, and visceral hypersensitivity is one of the most important pathological mechanisms. However, there are few reports on electroacupuncture treatment of functional dyspepsia from the perspective of visceral hypersensitivity mechanism.OBJECTIVE: To observe the effects and its possible mechanism of electroacupuncture at Zusanli(ST36) on visceral hypersensitivity in rats with functional dyspepsia. METHODS: Twenty-four 7-day-old male Sprague-Dawley rats were randomly divided into three groups: a control group, a model group, and an electroacupuncture group(n=8). The visceral hypersensitivity model of functional dyspepsia rats was prepared with multi-factor stress methods(intragastric administration of iodoacetamide+irregular feeding+Guo’s moderate clipping tail). In the electroacupuncture group, rats aged 8 weeks were treated with electroacupuncture intervention. A disposable sterile acupuncture needle was pierced into 7-10 mm at Zusanli acupoints of bilateral hind limbs of rats, which was connected with Hans-acupoint nerve stimulator(dilatational wave, 2/100 Hz, 1 mA). Electroacupuncture was performed 20 minutes per day, 5 consecutive days as one session with 2 days off, for 2 sessions in total. The average body mass of rats in different stages was computed. Mechanical pain threshold of the plantar was tested to detect visceral sensitivity of rats. Enzyme-linked immune sorbent assay(ELISA) was applied to detect the level of 5-hydroxytryptamine in serum and gastric fundus mucosa tissue. Real-time fluorescence quantitative PCR was used to assess the expression of exchange protein 1 directly activated by cAMP(EPAC1) and PIEZO2 mRNA in gastric fundus mucosa tissue. RESULTS AND CONCLUSION: Compared with the control group, the average body mass and plantar mechanical pain threshold were significantly decreased in the model group, and the level of 5-hydroxytryptamine in serum and gastric fundus mucosa was significantly increased(all P < 0.01). The mRNA expression levels of EPAC1 and PIEZO2 in gastric fundus mucosa were significantly increased in the model group compared with the control group(P < 0.01). Compared with the model group, in the electroacupuncture group, the average body mass and plantar mechanical pain threshold were significantly increased after 7 and 14 days of treatment(P < 0.05, P < 0.01), while the mRNA expression levels of EPAC1 and PIEZO2 in gastric fundus mucosa were significantly decreased(P < 0.01). These findings indicate that electroacupuncture at Zusanli can significantly improve the visceral hypersensitivity of functional dyspepsia rats, which is possibly mediated by regulating the release of 5-hydroxytryptamine from enterochromaffin cells and the mRNA expression of EPAC1 and PIEZO2.