Electroacupuncture improves senescence of ovarian granulosa cells by regulating P53/P21 signaling pathway in rats with premature ovarian insufficiency

OBJECTIVES: To observe the effect of electroacupuncture (EA) at "Gongsun" (SP4) on tumor suppressor protein 53 (P53)/cyclin-dependent inhibitor 21 (P21) pathway in rats with premature ovarian insufficiency (POI), so as to investigate its underlying mechanism in alleviating ovarian granulosa cell senescence. METHODS: Forty female SD rats were randomly divided into control, model, EA and medication groups, with 10 rats in each group. The POI model was established by intraperitoneal injection of cyclophosphamide (50 mg·kg⁻¹·d⁻¹ on the 1st day and 8 mg·kg⁻¹·d⁻¹ from the 2nd to 15th day, for a total of 15 days). After successful modeling, EA (0.1-1 mA, 2 Hz) was applied at bilateral SP4 for 20 min, once a day for 14 d. Rats of the medication group were treated by gavage of solution of estradiol valerate tablets (0.01 mg/mL, 1 mL/0.1 kg) once a day for 14 d. The changes in the estrous cycle, pregnancy rate and embryo number were observed. The senescence status of ovarian granulosa cells was observed by β-galactosidase staining. The contents of follicle-stimulating hormone (FSH), estradiol (E2), luteinizing hormone (LH), anti-Müllerian hormone (AMH), transforming growth factor β1 (TGF-β1), interleukin (IL)-6, and IL-1β in serum were detected by ELISA. The protein and mRNA expression levels of P53, P21, cyclin-dependent kinase inhibitor 2A (P16), and phosphorylated H2AX (γH2AX) in ovarian tissues were detected by Western blot and qPCR, respectively. RESULTS: After modeling, the rats' estrus cycles were disordered, mostly stagnated in proestrus and diestrus. Compared with the control group, the pregnancy rate, the number of embryos, and the contents of E2 and AMH were decreased (P<0.01) in the model group, while the contents of serum FSH, LH, IL-6, IL-1β and TGF-β1, the expression of P16, P21, P53 and γH2AX protein and mRNA in ovarian tissue were increased (P<0.01), with wild SAβ-gal blue staining in ovary. Compared with the model group, the pregnancy rate, the number of embryos, the contents of E2 and AMH were increased (P<0.01) in both EA and medication groups, while the contents of FSH, LH, IL-6, IL-1β and TGF-β1, the protein and mRNA expressions of P53, P21, P16 and γH2AX were significantly decreased (P<0.01, P<0.05), with reduced SAβ-gal blue staining in ovary. CONCLUSIONS: EA of SP4 can regulate the level of serum sex hormones, slow down the aging process of ovarian granulosa cells, improve the ovarian reserve function and fertility of POI rats, which may be related to its function in regulating P53/P21 signaling pathway.