Objective: To observe the effect of electroacupuncture (EA) at different acupoints on follicle development, expression of gonadotropins and their receptors and anti-Müllerian hormone(AMH), inhibin B(INHB) in polycystic ovarian syndrome (PCOS) rats, so as to explore its mechanisms underlying improvement of PCOS.
Methods: Sixty female SD rats were randomized into six groups: control, model, Zusanli(ST36), Sanyinjiao(SP6), Guanyuan(CV4) and combination (ST36+SP6+CV4, n=10 rats/group). The PCOS model was established by gavage of Letrozole solution (1.0 mg/kg) once daily for 21 consecutive days. Rats of the control group were given 1% Carboxymethyl Cellulose (CMC, 1 mg/kg). EA (2 Hz) was applied to ST36, SP6, or/and CV4 for 20 min, once daily for 14 consecutive days. The number of follicles was counted, and the ovarian structure and follicular development were observed under light microscope after H.E. stain, and the contents of serum luteinizing hormone (LH), follicle-stimulating hormone (FSH), AMH, and INHB were assayed by enzyme-linked immunosorbent assay, and the ratio of LH/FSH was calcula-ted. The immunoactivity of LH receptor (LHR) and FSH receptor (FSHR) proteins was detected by immunohistochemistry.
Results: After modeling, the number of follicles at the growth stage, contents of serum LH, AMH and INHB, and ratio of LH/FSH were significantly increased, and serum FSH level and FSHR, LHR immunoactivity were remarkably decreased in the model group relevant to the control group (P<0.05, P<0.01). Following EA intervention, the number of follicles at the growth stage in the SP6, CV4 and combination groups, LH/FSH ratio and serum AMH levels in the 4 EA groups, INHB contents in the ST36, CV4 and combination groups were significantly reduced (P<0.05, P<0.01), while serum FSH contents in the 4 EA groups, FSHR immunoactivity at the early stage in the ST36 group and LHR immunoactivity at both early and late stages in the ST36 and CV4 groups were considerably increased in comparison with those of the model group (P<0.01, P<0.05). The therapeutic effect of SP6 was significantly superior to that of CV4 in down-regulating serum LH level (P<0.01), but significantly inferior to that of CV4 in up-regulating serum FSH content and in down-regulating LH/FSH ratio and serum AMH and INHB levels (P<0.05, P<0.01). The effect of CV4 was comparable to that of ST36 in up-regulating serum FSH, and in down-regulating serum LH/FSH ratio, AMH and INHB levels (P>0.05).
Conclusion: EA of CV4, SP6, ST36 and ST36+CV4+SP6 can reduce the number of follicles at the growth stage and regulate the expression levels of gonadotropins in PCOS rats. The effects of EA of CV4 and ST36 are evidently better than those of EA of SP6 in up-regulating serum FSH content and in down-regulating LH/FSH ratio, and serum AMH and INHB levels, and EA of SP6 is evidently superior to EA of CV4 down-regulating LH level, but without synergistic effect among the 3 acupoints.
Keywords: Electroacupuncture; Follicle development; Gonadotropins; Polycystic ovarian syndrome; Receptor.