[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

Objective: 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.

Methods: 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.

Results: 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).

Conclusion: 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.

Keywords: 5-hydroxytryptamine; Siguan points; acupuncture; electroacupuncture; post-stroke depression; short chain fatty acids.