Objective To observe the effect of electroacupuncture(EA) on mast cell activation-related substances and intestinal barrier function in diarrhea-predominant irritable bowel syndrome(IBS-D) model rats

so as to explore its underlying mechanisms. Methods Thirty female SD rats were randomly divided into control group

model group and EA group

with 10 rats in each group. IBS-D model was established by chronic unpredictable mild stress combined with senna solution gavage. Rats in the EA group received EA treatment(2 Hz/15 Hz

0.1-1.0 mA) at “Zusanli”(ST36)

“Taichong”(LR3) and “Tianshu”(ST25)

20 min per day

for a total of 14 days

with sides alternated daily. Visceral pain threshold was used to evaluate visceral hypersensitivity

diarrhea index was used to evaluate diarrhea degree. After all treatments

the pathological scores of colon were recorded after HE staining

the contents of cholecystokinin(CCK)

substance P(SP)

tryptase(TPS) and adenosine triphosphate(ATP) in colon were detected by ELISA

and the expressions of colonic tight junction protein ZO-1 and occludin were detected by Western blot. Results Compared with the control group

the visceral pain threshold

the expression levels of colonic ZO-1 and occludin proteins decreased(P<0.01)

while the diarrhea index

the contents of colonic CCK

SP

TPS and ATP were significantly increased(P<0.01) in the model group. After intervention

in comparison with the model group

the visceral pain thre-shold

the protein expression levels of colonic ZO-1 and occludin protein increased(P<0.01)

while the diarrhea index

the contents of colonic CCK

SP

TPS and ATP were significantly decreased(P<0.01) in the EA group. Conclusion EA can significantly alleviate the symptoms of visceral hypersensitivity and diarrhea in IBS-D rats. Its mechanism may be related to down-regulating colonic CCK

SP

TPS and ATP

inhibiting mast cell activation and degranulation

and up-regulating colonic barrier tight junction proteins.