Effect of electroacupuncture on gut microbiota and serum IL-1β and IL-18 in rats with vascular dementia based on principle of "curing brain disorders by treating intestines"

Abstract

To observe the effect of electroacupuncture (EA) of "Baihui"(GV20), "Dazhui"(GV14), "Shenshu" (BL23)and "Zusanli"(ST36) on the intestinal flora and serum interleukin (IL)-1β and IL-18 contents in vascular dementia (VD) rats. SD rats were randomized into sham operation, VD model, GV20+GV14+BL23 (EA-basic acupoints), and EA-basic acupoints+ST36 and EA-basic acupoints+probiotics groups (n=10 in each group). EA (10 Hz/50 Hz) was conducted for 30 min, once daily for 4 consecutive weeks. Rats of the EA-basic acupoints+probiotics received gavage of probiotics (2 mL/d containing 2.0×109 CFU of live bifidobacterium), once a day for 4 weeks, and those of the EA-basic acupoints and EA-basic acupoints+ST36 groups received gavage of the same dose of normal saline. The Morris water maze test was used to evalua-te the rats' lear-ning and memory ability before and after the treatment. The serum IL-1β and IL-18 levels were determined by ELISA, and the histopathological changes of the intestinal mucosa were observed by H.E. staining. The ultrastructural changes of hippocampal neurons were observed by using transmission electron microscopy and 16S rDNA sequencing technique was used to analyze the composition of intestinal microbiome. Compared with the sham operation group, the escape latency, serum levels of IL-1β and IL-18, as well as the relative abundance of harmful bacteria (including Catabacter, obinsoniella and Desulfovibrio) in the intestine were significantly increased (P<0.01). In comparison with the model group, the escape latency, serum levels of IL-1β and IL-18 in the three treatment groups, and the relative abundance of harmful bacteria (such as the Catabacter, Robinsoniella and Desulfovibrio) in the EA-basic acupoints+ST36 group were down-regulated obviously(P<0.05,P<0.01), and the relative abundance of Clostridiales-unclassified in both EA-basic acupoints+probiotics and EA-basic acupoints+ST36 groups was significantly up-regulated (P<0.05). The effects of EA-basic acupoints+ST36 and EA-ba-sic acupoints+probiotics were significantly superior to that of EA-basic acupoints in down-regulating IL-18 content (P<0.05). H.E. staining showed atrophy of the whole mucosal layer, loss of goblet cells, destruction of glands, infiltration of a large number of inflammatory cells, and transmission microscope displayed fuzziness of the nucleus membrane boundary, cystic dilation of the rough endoplasmic reticulum with unclear structure swelling of the mitochondria, and disordered arrangement or dissolution of the inner cristae in the model group, which was relatively milder in the EA-basic acupoints+ST36 and EA-basic acupoints+probiotics groups. EA of GV20+GV14+BL23+ ST36 can improve the cognitive dysfunction of VD model rats, which may be related to its function in regulating the imbalance of intestinal microbiota, thereby inhibiting the peripheral inflammatory factor.