Mechanisms of electroacupuncture relieves uterine smooth muscle spasm in dysmenorrhea rats based on Rho/ROCK signaling pathway.

Objectives: To investigate the effect of electroacupuncture (EA) on Rho/Rho-associated coiled-coil-forming kinases (ROCK) signaling pathway of uterus tissue in rats with dysmenorrhea, so as to explore the underlying mechanism of EA treating primary dysmenorrhea (PD) and uterine smooth muscle spasm, and to observe whether there is a difference in the effect of meridian acupoints in Conception Vessel (CV) and Governer Vessel (GV).

Methods: Sixty female SD rats were randomly divided into saline, model, CV, GV, and non-acupoint groups, with 12 rats in each group. The dysmenorrhea model was established by subcutaneous injection of estradiol diphenhydrate combined with intraperitoneal injection of oxytocin (OT). EA (2 Hz) was applied to "Qihai" (CV6) and "Zhongji" (CV3) for CV group, "Mingmen" (GV4) and "Yaoshu" (GV2) for GV group, "non-acupoint 1" and "non-acupoint 3" on the left side for non-acupoint group, and manual acupuncture was applied to "Guanyuan" (CV4) for CV group, "Yaoyangguan" (GV3) for GV group, "non-acupoint 2" on the left side for non-acupoint group. The treatment was conducted for 20 min each time, once daily for 10 days. The writhing score was evaluated. The smooth myoelectric signals of rats' uterus were recorded by multi-channel physiological recorder. The uterine histopathological changes were observed by HE staining. The contents of prostaglandin F2α (PGF), OT and calcium ion (Ca) in uterine tissue of rats were detected by ELISA. The protein and mRNA expression levels of smooth muscle 22-α (SM22-α), RhoA and ROCKⅡ in uterine tissue were detected by Western blot and fluorescence quantitative PCR, respectively.

Results: Compared with the saline group, the writhing score of rats in the model group was increased (<0.01), the amplitude voltage of uterine smooth muscle was elevated (<0.01), the contents of PGF, OT and Ca, the protein and mRNA expression of SM22-α, RhoA and ROCK Ⅱ in uterine tissue were all increased (<0.01). Compared with the model and the non-acupoint groups, the writhing scores of the CV and the GV groups were decreased (<0.01, <0.05), the amplitude voltage of uterine smooth muscle was decreased (<0.01), the contents of PGF, OT and Ca in uterine tissue were decreased (<0.01, <0.05), and the protein expression and mRNA expression of SM22-α, RhoA and ROCKⅡ in uterine tissue were decreased (<0.01, <0.05). HE staining showed extensive exfoliation of uterine intima with severe edema and increased glandular secretion in the model group, which was alleviated in the CV and GV groups.

Conclusions: EA at acupoints of CV and GV can significantly reduce the writhing score, uterine smooth muscle amplitude voltage, pathological injury degree of uterus, and relieve spasm of uterine smooth muscle in dysmenorrhea rats, which may be related to its effect in regulating PGF and OT contents, inhibiting the Rho/ROCK signaling pathway, and reducing the SM22-α, RhoA, ROCKⅡ protein and mRNA expression, and Ca content in uterine tissue.