[Effect of electroacupuncture intervention on relieving pain and inflammation by suppressing TLR4/NF-κB signaling in rats with primary dysmenorrhea].

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 11th 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(<0.01), while PGE2 contents in serum and uterine tissues were significantly decreased(<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(<0.01), while writhing incubation period, PGE2 contents in serum and uterine tissues were significantly increased(<0.05, <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.