Polycystic ovary syndrome: effect and mechanisms of acupuncture for ovulation induction

Abstract

Polycystic ovary syndrome (PCOS), the most common endocrine disorder among women of reproductive age, is characterized by the coexistence of hyperandrogenism, ovulatory dysfunction, and polycystic ovaries (PCO). PCOS also represents the largest part of female oligoovulatory infertility, and the management of ovulatory and menstrual dysfunction, comprises a third of the high costs of PCOS treatment. Current pharmacological and surgical treatments for reproductive symptoms are effective, however, associated with negative side effects, such as cardiovascular complications and multiple pregnancies. For menstrual irregularities and ovulation induction in women with PCOS, acupuncture has indicated beneficial effects. This review will focus on the results from randomized controlled acupuncture trials for regulation of menstrual dysfunction and for inducing ovulation in women with PCOS although there are uncontrolled trials with nonetheless interesting results. Animal experimental studies will be further discussed when they can provide a more mechanistic explanatory view.

Figure 1

Summary of the PCOS pathophysiology. (1) Ovarian androgens are the main source of hyperandrogenemia in PCOS. Hyperandrogenemia has both a direct effect on the ovarian alterations and (2) an increasing effect on pituitary LH pulse frequency and amplitude with relative low FSH secretion. (3) Further, adrenal androgens contribute to PCOS androgen excess. (4) Insulin resistance with compensatory hyperinsulinemia enhances ovarian androgen production as well as (5) decreases production of SHBG in the liver, and both increase the pool of bioavailable androgens. (6) PCOS is also associated with increased muscle sympathetic nerve activity that is related to high testosterone, insulin resistance, and obesity. (7) Genetic defects probably contribute to the pathology of PCOS. LH: luteinizing hormone, FSH: follicle stimulating hormone, SHBG: sex hormone binding globulin, DHEA: dehydroepiandrosterone, and DHEAS: dehydroepiandrosterone sulphate.

Figure 2

Schematic illustration of steroid synthesis in the ovary.

Figure 3

Schematic illustration of a hypothetical mechanism explaining the effects of acupuncture in PCOS. (1) Stimulation of acupuncture needles in skeletal muscle excites ergoreceptors that activate afferent sensory nerve fibers. These signals are transmitted to the spinal cord where they (2) through spinal reflexes may modulate the sympathetic output to the target organs in the same area of innervation. (3) Signals also reach the central nervous system via supraspinal pathways where they can exert central effects. Hypothalamic β-endorphin is implicated in the effect of acupuncture. It modulates the autonomic system but may also alter the release of GnRH and CRH. (4) These can enable an effect on reproductive function (via LH and FSH), adrenal function (ACTH), and pancreatic function (circulating β-endorphins). (ACTH: adrenocorticotrophic hormone, CNS: central nervous system, CRH: corticotrophin releasing hormone, EA: electroacupuncture, FFA: free fatty acids, FSH: follicle stimulating hormone, GnRH: gonadotropin releasing hormone, and LH: luteinizing hormone).