[Effects of acupuncture on fecal short-chain fatty acids and TLR4/MyD88/NF-κB signaling pathway in spontaneously hypertensive rats].

Objective: To observe the effects of acupuncture on blood pressure, fecal short-chain fatty acids (SCFAs) and toll-like receptor 4 (TLR4)/myeloid differentiation factor 88 (MyD88)/nuclear factor-κB (NF-κB) signaling pathway in spontaneously hypertensive rats (SHR), and to explore the mechanism of acupuncture for anti-hypertension.

Methods: Twenty-four male SHR of SPF grade were randomly divided into a model group, a western medication group, an acupuncture group and a sham acupuncture group, with 6 rats in each group, and 6 male Wistar-Kyoto rats were selected as the blank group additionally. Hydrochlorothiazide solution was given by gavage in the western medication group; acupuncture was applied at bilateral "Renying" (ST 9) and "Zusanli" (ST 36) in the acupuncture group, 20 min a time; acupuncture was applied at the non-meridian and non-acupoint points close to bilateral "Renying" (ST 9) and "Zusanli" (ST 36) in the sham acupuncture group, 20 min a time. The intervention was adopted once a day for 4 weeks continuously in each group. The systolic blood pressure (SBP) of the caudal artery was measured before intervention and after 1, 2, 3 and 4 weeks of intervention. After intervention, the morphology of colonic tissue was observed by HE staining; the fecal level of SCFAs was detected by gas chromatography; the serum levels of interleukin (IL)-6, IL-1βand tumor necrosis factor-α (TNF-α) were detected by ELISA; the protein expression of TLR4, MyD88 and NF-κB p65 in the mesenteric artery was detected by Western blot.

Results: Compared with the blank group, in the model group, the SBP was increased (<0.05), significant pathological changes could be found in the colonic tissue, the fecal SCFAs level was decreased (<0.05), the serum levels of IL-6, IL-1β and TNF-α were increased (<0.05), the protein expression of TLR4, MyD88 and NF-κB p65 in the mesenteric artery was increased (<0.05). Compared with the model group, the SBP after 2, 3 and 4 weeks of intervention was decreased (<0.05), the serum levels of IL-6, IL-1β and TNF-α were decreased (<0.05) in the acupuncture group and the western medication group; the mucosal epithelium of colonic tissue was intact, the number of intestinal glands was abundant, the fecal SCFAs level was increased (<0.05), and the protein expression of TLR4, MyD88 and NF-κB p65 in the mesenteric artery was decreased (<0.05) in the acupuncture group. Compared with the sham acupuncture group, the SBP after 2, 3 and 4 weeks of intervention was decreased (<0.05), the fecal SCFAs level was increased (<0.05), the serum levels of IL-6, IL-1β and TNF-α were decreased (<0.05), the protein expression of TLR4, MyD88 and NF-κB p65 in the mesenteric artery was decreased (<0.05) in the acupuncture group.

Conclusion: Acupuncture at bilateral "Renying" (ST 9) and "Zusanli" (ST 36) can effectively play an anti-hypertensive role in SHR. Its mechanism may be related to regulating fecal SCFAs level and inhibiting the TLR4/MyD88/NF-κB signaling pathway.