Effects of electroacupuncture at "Siguan" points on the expression of colonic 5-hydroxytryptamine and fecal short-chain fatty acids in rats with post-stroke depression

Abstract

To observe the effects of electroacupuncture at "Siguan" points on behavior, colonic 5-hydroxytryptamine (5-HT) and fecal short-chain fatty acids (SCFAs) in rats with post-stroke depression (PSD), and explore the effect mechanism of electroacupuncture at Siguan points on PSD.Fifty SD rats were randomly divided into a sham-operation group, a stroke group, a PSD group, a drug group and an electroacupuncture group, with 10 rats in each one. The stroke model was established by middle cerebral artery occlusion (MCAO) method in the stroke group; except for the sham-operation group, the rats in the other groups were intervened with MCAO combined with solitary and chronic unpredictable mild stress (CUMS) to establish PSD model. In the electroacupuncture group, electroacupuncture was delivered at "Hegu" (LI 4) and "Taichong" (LR 3), with disperse-dense wave, 2 Hz/10 Hz in frequency, for 30 min in each intervention, once daily, for consecutive 21 days. Simultaneously, distilled water (0.01 L•kg-1•d-1) was administrated intragastrically. Fluoxetine solution (2.33 mg•kg-1•d-1) was given by gavage , once a day and for 21 days in the drug group. The same procedure of fixation and gavage with distilled water were adopted in the sham-operation group, the stroke group and the PSD group. Separately, before stroke modeling, after PSD modeling and after 21-day intervention, the consumption of sugar water and the scores of horizontal movement and vertical movement in open-field test were observed. After 21-day intervention, the content of colonic 5-HT was detected by immunohistochemical method, and that of fecal SCFAs was determined by gas chromatography mass spectrometry.After PSD modeling, compared with the stroke group, the sugar water consumption, the horizontal movement scores and vertical movement scores of the open-field test were all reduced in the PSD group, the drug group and the electroacupuncture group (P<0.05). After 21-day intervention, the sugar water consumption and the scores of horizontal movement and vertical movement of the open-field test were increased in the drug group and the electroacupuncture group (P<0.05) when compared with the PSD group; and the horizontal movement score in the electroacupuncture group was lower than that of the drug group (P<0.05). Compared with the sham-operation group, the contents of total fecal SCFAs and acetic acid were lower in the stroke group (P<0.05), and the contents of colonic 5-HT and total fecal SCFAs, acetic acid, propionic acid and butyric acid were reduced in the PSD group (P<0.05). In comparison with the PSD group, the contents of colonic 5-HT and total fecal SCFAs, acetic acid and propionic acid were increased in the drug group and the electroacupuncture group (P<0.05); and the content of colonic 5-HT in the electroacupuncture group was lower than that of the drug group (P<0.05). The level of colonic 5-HT was positively correlated with the contents of total fecal SCFAs and propionic acid (r=0.424, P=0.005; r=0.427, P=0.004).Electroacupuncture at "Siguan" points can relieve the depression-like behavior of PSD rats, and its underlying mechanism may be related to the regulation of fecal SCFAs, which affects the release of colonic 5-HT.目的：观察电针“四关”穴对卒中后抑郁（PSD）大鼠行为学、结肠5-羟色胺（5-HT）、粪便短链脂肪酸（SCFAs）的影响，探讨电针四关穴治疗PSD的作用机制。方法：将50只SD大鼠随机分为假手术组、卒中组、PSD组、药物组和电针组，每组10只。除假手术组外，其余各组采用大脑中动脉栓塞（MCAO）法制备卒中模型；除假手术组和卒中组外，其余组大鼠采用MCAO结合孤养和慢性不可预知性温和应激（CUMS）法制备PSD模型。电针组予电针“合谷”“太冲”干预，疏密波，频率2 Hz/10 Hz，每次30 min，每日1次，持续21 d，同时予蒸馏水（0.01 L•kg-1•d-1）灌胃；药物组予氟西汀溶液（2.33 mg•kg-1•d-1）灌胃，每日1次，持续21 d；假手术组、卒中组、PSD组予同等固定束缚、蒸馏水灌胃。分别于卒中造模前、PSD造模后、干预21 d后观察大鼠糖水消耗量及敞箱实验水平运动得分、垂直运动得分；干预21 d后，采用免疫组化法检测结肠5-HT水平，气相质谱法测定粪便短链脂肪酸含量。结果：PSD造模后，与卒中组比较，PSD组、药物组、电针组大鼠糖水消耗量及敞箱实验水平运动得分、垂直运动得分均降低（P<0.05）。干预21 d后，与PSD组比较，药物组、电针组糖水消耗量及敞箱实验水平运动得分、垂直运动得分均升高（P<0.05）；电针组水平运动得分低于药物组（P<0.05）。与假手术组比较，卒中组粪便总短链脂肪酸及乙酸含量均降低（P<0.05），PSD组结肠5-HT水平及粪便总短链脂肪酸、乙酸、丙酸、丁酸含量均降低（P<0.05）；与PSD组比较，药物组和电针组结肠5-HT水平及粪便总短链脂肪酸、乙酸、丙酸含量均升高（P<0.05）；电针组结肠5-HT水平低于药物组（P<0.05）。结肠5-HT水平与粪便总短链脂肪酸、丙酸含量存在正相关关系（r=0.424，P=0.005；r=0.427，P=0.004）。结论：电针“四关”穴可改善PSD大鼠抑郁样行为，可能与调控粪便短链脂肪酸含量，从而影响结肠5-HT释放有关。.