Objective To investigate the mechanism of electroacupuncture(EA) intervention in rats with primary dysmenorrhea(PDM) based on the Toll-like receptor 4(TLR4)/nuclear factor(NF)-κB signaling pathway. Methods Forty female SD rats were randomly divided into blank control

model

EA and medication groups

with 10 rats in each group. PDM rat model was established by subcutaneous injection of estradiol benzoate combined with intraperitoneal injection of oxytocin. At the same time of model procedures

EA(50 Hz

dense wave) was applied to “Guanyuan”(CV4) and bilateral “Sanyinjiao”(SP6) of rats in the EA group

with needles retained for 20 min

for 10 consecutive days. Rats in the medication group received ibuprofen(125 mg/100 mL

0.8 mL) by gavage for 10 consecutive days. At the 11

(th)

day

writhing behavior of rats was assessed. Uterine morphology was observed by eyes and uterine pathological changes were observed after HE staining. Content of prostaglandin E2(PGE2) and prostaglandin F2α(PGF2α) in serum and uterine tissues was detected by ELISA; NF-κB p65 positive expression in nucleus was detected by immunofluorescence; protein expression levels of TLR4

NF-κB p65

p-NF-κB p65 and inflammatory factors interleukin(IL)-1β and IL-18 were detected by Western blot. Results After modeling

uterus tissues were congested and edematous

with necrosis of luminal epithelium

severe edema and extensive shedding of endometrium

nuclear pyknosis

fragmentation and disappearance

neutrophils infiltration

and slight expansion of glandular cavity

which was milder in the EA and the medication groups. Compared with the blank control group

writhing times

scores and incubation period

HE pathological scores

PGF2α contents in serum and uterine tissues

ratio of NF-κB p65 positive expression in nucleus

TLR4

NF-κB p65

p-NF-κB p65

IL-1β and IL-18 protein expression levels in uterine tissues of rats in the model group were all significantly increased(P

<

0.01)

while PGE2 contents in serum and uterine tissues were significantly decreased(P

<

0.01). Compared with the model group

writhing times and scores

HE pathological scores

PGF2α contents in serum and uterine tissues

ratio of NF-κB p65 positive expression in nucleus

TLR4

NF-κB p65

p-NF-κB p65

IL-1β and IL-18 protein expression levels in uterine tissues of rats in the EA and medication group were all significantly decreased(P

<

0.01)

while writhing incubation period

PGE2 contents in serum and uterine tissues were significantly increased(P

<

0.05

P

<

0.01). Conclusion EA intervention could relieve inflammatory response and pain in PDM rats

which may be related to its effect in reducing TLR4 expression

inhibiting NF-κB activation and down-regulating inflammatory factors levels of IL-1β and IL-18.