Objective To investigate the protective effect of electroacupuncture(EA) on rats with ulcerative colitis(UC) and its effect on the Toll-like receptor 4(TLR4)/myeloid differentiation factor 88(MyD88)/nuclear factor-kappa B(NF-κB) signaling pathway. Methods Sprague-Dawley rats were randomly divided into blank group

model group

salicylazosulfapyridine(SASP) group

low-intensity EA group

and high-intensity EA group

with 8 rats in each group. Enema with 2

4

6-trinitrobenzenesulfonic acid was performed to establish a model of UC. The rats in the two EA groups were given EA at"Tianshu"(ST25)

"Guanyuan"(CV4)

and "Zusanli"(ST36) for 15 min each time

once a day

with a current intensity of 1 mA for the low-intensity EA group and 5 mA for the high-intensity EA group(among them

"Tianshu" "Zusanli" bilateral alternate acupoints); the rats in the SASP group were given SASP suspension 3 mL every day by gavage. The course of treatment was 15 days for all groups. HE staining was used to observe the pathology of the colon and determine tissue damage index(TDI); ELISA was used to measure the serum levels of interleukin-4(IL-4)

interleukin-10(IL-10)

interleukin-17(IL-17)

and prostaglandin E_2(PGE_2); immunohistochemical staining and real-time PCR were used to measure the protein and mRNA expression of TLR4

MyD88

and NF-κB in colonic tissue. Results Compared with the blank group

the model group had significant reductions in body weight

serum IL-4

and IL-10(P<0.05) and significant increases in colonic mucosa TID

the serum levels of IL-17 and PGE_2 and the protein and mRNA expression of TLR4

MyD88

and NF-κB in colonic tissue(P<0.05). Compared with the model group

the SASP group and the EA groups had significantly higher body weight and serum levels of IL-4 and IL-10(P<0.05)

as well as significantly lower colonic TDI

serum levels of IL-17 and PGE_2

and integrated optical density and mRNA expression of TLR4

MyD88

and NF-κB in colonic tissue(P<0.05). Compared with the SASP group

the low-intensity EA group had significantly higher colonic TDI and protein and mRNA expression of TLR4

MyD88

and NF-κB in colonic tissue(P<0.05)

and compared with the SASP group

the high-intensity EA group had a significantly higher body weight(P<0.05) and lower colonic TDI and protein and mRNA expression of TLR4

MyD88

and NF-κB in colonic tissue(P<0.05). Compared with the low-intensity EA group

the high-intensity EA group had significantly higher body weight(P<0.05)

and lower colonic TDI and protein and mRNA expression of TLR4

MyD88

and NF-kB in colonic tissue(P<0.05). Conclusion Electroacupuncture exerts a protective effect on the colonic mucosa in rats with UC possibly by inhibiting the TLR4/MyD88/NF-κB signaling pathway and reducing the release of inflammatory cytokines

and high-intensity EA may have a better effect than low-intensity EA.