Objective: To observe the effect of electroacupuncture (EA) at "Zhongliao" (BL33) and "Xialiao" (BL34) on the 5-hydroxytryptamine (5-HT) signaling system in colon tissue and short-chain fatty acids in feces of rats with slow transit constipation (STC), so as to explore the underlying mechanisms of EA in the treatment of STC.
Methods: A total of 32 SD rats were randomly divided into normal, model, drug control and EA groups, with 8 rats in each group. The STC model was established by intragastric administration of loperamide for 14 days. The EA stimulation (2 Hz/15 Hz) was performed at bilateral BL33 and BL34 for 30 min, once a day for 14 days. The first black stool de-fecation time and fecal water content were detected after treatment. The expressions of 5-hydroxytryptamine 4 receptor (5-HT4R), tryptophan hydroxylase 1 (TPH1) and 5-HT transporter (SERT) in colon tissues were detected by Western blot. The contents of substance P (SP) and vasoactive intestinal peptide (VIP) in serum were detected by ELISA. The contents of 5-HT in colon tissue and short chain fatty acid (SCFA) in feces were detected by mass spectrometry.
Results: Compared with the normal group, the fecal water content, the expressions of 5-HT, 5-HT4R, TPH1 and SERT in colon tissue, the content of serum SP were significantly decreased (P<0.05), the first black stool de-fecation time, and the content of serum VIP was significantly increased (P<0.05), the contents of SCFA in feces were significantly decreased except isobutyric acid (P<0.05) in the model group. Compared with the model group, the fecal water content, the expressions of 5-HT, 5-HT4R, TPH1 and SERT in colon tissues, the contents of acetic acid and butyrate in feces were significantly increased (P<0.05) in the EA and drug control groups, the first black stool defecation time was decreased (P<0.05) in the EA and drug control groups, and the content of serum SP was increased and the content of serum VIP was decreased (P<0.05) in the EA group. Compared with the drug control group, the content of serum VIP was significantly decreased (P<0.05), and the expressions of TPH1 and SERT in colon tissue were significantly increased (P<0.05) in the EA group.
Conclusion: EA at BL33 and BL34 can promote intestinal motility by intervening multiple links of 5-HT signaling system in treating STC.
目的：观察电针“中髎”“下髎”对慢传输型便秘(STC)大鼠结肠5-羟色胺(5-HT)信号系统及粪便中短链脂肪酸(SCFA)的影响，探讨电针治疗STC的作用机制。方法：SD大鼠随机分为正常组、模型组、阳性药组及电针组，每组8只。采用洛哌丁胺灌胃建立STC大鼠模型。阳性药组予6 g/kg乳果糖灌胃治疗，电针组电针“中髎”“下髎”，每次30 min，两组均每日治疗1次，连续干预14 d。观察各组大鼠首粒黑便排出时间及粪便含水率；Western blot法检测各组大鼠结肠组织中5-羟色胺4受体(5-HT4R)、色氨酸羟化酶1(TPH1)、5-HT转运体(SERT)相对表达量；ELISA法检测各组大鼠血清P物质(SP)、血管活性肠肽(VIP)含量；高效液相色谱-质谱联用法检测各组大鼠结肠组织中5-HT含量及粪便中SCFA含量。结果：与正常组比较，模型组大鼠首粒黑便排出时间延长(P<0.05)，粪便含水率降低(P<0.05)；结肠组织中5-HT含量及5-HT4R、TPH1、SERT蛋白表达量降低(P<0.05)；血清SP含量降低(P<0.05)，VIP含量升高(P<0.05)；粪便SCFA含量（除异丁酸外）均显著降低(P<0.05)。与模型组比较，电针组和阳性药组大鼠首粒黑便排出时间缩短(P<0.05)，粪便含水量升高(P<0.05)；结肠组织中5-HT含量及5-HT4R、TPH1、SERT蛋白表达量升高(P<0.05)；粪便中乙酸及丁酸含量均明显升高(P<0.05)；电针组血清SP含量升高(P<0.05)，VIP含量降低(P<0.05)。电针组大鼠血清VIP含量较阳性药组显著降低(P<0.05)；结肠组织TPH1、SERT蛋白表达量较阳性药组显著升高(P<0.05)。结论：电针“中髎”“下髎”可以通过干预5-HT信号系统的多个环节促进肠道动力，从而缓解STC。.
Keywords: Serotonin signaling system; Electroacupuncture; Slow transit constipation; Xialiao (BL34); Zhongliao (BL33).