RESUMO
Acupuncture with combined manual and low-frequency electrical stimulation, or electroacupuncture (EA), reduces endocrine and reproductive dysfunction in women with polycystic ovary syndrome (PCOS), likely by modulating sympathetic nerve activity or sex steroid synthesis. To test this hypothesis, we induced PCOS in rats by prepubertal implantation of continuous-release letrozole pellets (200 µg/day) or vehicle. Six weeks later, rats were treated for 5-6 weeks with low-frequency EA 5 days/week, subcutaneous injection of 17ß-estradiol (2.0 µg) every fourth day, or a ß-adrenergic blocker (propranolol hydrochloride, 0.1 mg/kg) 5 days/week. Letrozole controls were handled without needle insertion or injected with sesame oil every fourth day. Estrous cyclicity, ovarian morphology, sex steroids, gonadotropins, insulin-like growth factor I, bone mineral density, and gene and protein expression in ovarian tissue were measured. Low-frequency EA induced estrous-cycle changes, decreased high levels of circulating luteinizing hormone (LH) and the LH/follicle-stimulating hormone (FSH) ratio, decreased high ovarian gene expression of adiponectin receptor 2, and increased expression of adiponectin receptor 2 protein and phosphorylation of ERK1/2. EA also increased cortical bone mineral density. Propranolol decreased ovarian expression of Foxo3, Srd5a1, and Hif1a. Estradiol decreased circulating LH, induced estrous cycle changes, and decreased ovarian expression of Adipor1, Foxo3, and Pik3r1. Further, total bone mineral density was higher in the letrozole-estradiol group. Thus, EA modulates the circulating gonadotropin levels independently of sex steroids or ß-adrenergic action and affects the expression of ovarian adiponectin system.