PCOS Forum

Research in Polycystic Ovary Syndrome Today and Tomorrow

Renato Pasquali; Elisabet Stener-Victorin; Bulent O. Yildiz; Antoni J. Duleba; Kathleen Hoeger; Helen Mason; Roy Homburg; Theresa Hickey; Steve Franks; Juha S. Tapanainen; Adam Balen; David H. Abbott; Evanthia Diamanti-Kandarakis; Richard S. Legro

Disclosures

Clin Endocrinol. 2011;74(4):424-433. 

In This Article

Sympathetic Nerve Activity and Hyperandrogenism

Many factors associated with PCOS are also associated with increased activity in the sympathetic nervous system.[20] The involvement of sympathetic nervous system in PCOS pathology is supported by the greater density of catecholaminergic nerve fibres in PCO.[21] Increased ovarian sympathetic nerve activity might contribute to PCOS by stimulating androgen secretion.[22] Nerve growth factor (NGF) is a strong marker for sympathetic nerve activity, and recently, it was demonstrated that women with PCOS has enhanced ovarian NGF production.[23] In a transgenic mouse model overexpressing NGF in the ovaries, they found that that a persistent elevation in plasma luteinising hormone (LH) levels is required for the typical morphological abnormalities to appear.[23] These results suggest that overproduction of ovarian NGF is a component of PCO morphology.

Studies using indirect markers of autonomic function – heart rate variability and heart rate recovery after exercise – have shown that women with PCOS have increased sympathetic and decreased parasympathetic components.[24–26] Recently, for the first time, it was demonstrated that women with PCOS have high general activity in the sympathetic nervous system, which may be relevant to the pathophysiology of the syndrome.[27] Interestingly, testosterone was the strongest independent factor explaining high sympathetic nerve activity in women with PCOS.[27] As the degree of androgen concentration can reflect the severity of PCOS, the relationship between sympathetic nerve activity and testosterone concentration indicates that the degree of sympatho-excitation is related to the degree of PCOS severity.

Recently, a randomized, controlled trial demonstrated that low-frequency electro-acupuncture (EA) and physical exercise (both known to modulate sympathetic nerve activity) decrease high levels of circulating sex steroid precursors, oestrogens, androgens and glucuronidate androgen metabolites and improve menstrual bleeding pattern in women with PCOS, and thus break the vicious circle of androgen excess.[28] In a subset of these women, low-frequency EA and physical exercise were shown to decrease high sympathetic nerve activity in women with PCOS,[29] which may at least in part explain the beneficial effects of these therapies. It may also be hypothesized that therapies such as ovarian wedge resection or laparoscopic laser cauterization[30] utilize its effect by temporary disruption of ovarian sympathetic innervation, and thus increase ovulatory function and decrease androgen synthesis in women with PCOS.

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