Polycystic ovary syndrome (PCOS) : role of androgens and obesity on placental function and fetal development

Abstract

Polycystic ovary syndrome (PCOS) is a common endocrine and metabolic disorder affecting women in childbearing age with a prevalence of up to 17.8%. The syndrome is characterized by hyperandrogenism, irregular cycles and polycystic ovaries. The etiology of PCOS is unclear, but it is thought to be multifactorial. There is a strong association between hyperinsulinemia and hyperandrogenism in PCOS, but the mechanisms behind their relationship with PCOS are not fully understood. Obesity and an aberrant metabolic profile is common in women with PCOS, and 50-70% of them are insulin resistant, which increase the risk of developing type 2 diabetes (T2D), independently of body mass index (BMI) and age.

Women with PCOS have a reduced fertility rate, and when they become pregnant either by natural process or by assisted reproduction techniques, they are at higher risk of developing pregnancy complications including preeclampsia and gestational diabetes that worsen the prognosis of their own health and the health of the fetus. It is not well known if and how the intrauterine environment affects the fetus. In women with PCOS, a potential effect on the fetus can be hypothetically driven by direct exposure of high maternal androgens to the fetus or via dysregulation of placenta function. In both non-pregnant and pregnant women with PCOS, lifestyle modification including diet and physical exercise is the first line treatment. However, scarce information about treatment of pregnant women with PCOS to prevent the adverse outcomes is found in the literature. Acupuncture has been proposed as one treatment as has been shown to increase uterine artery blood flow in non-pregnant women. Importantly, acupuncture is usually reported to have less negative side-effects than pharmacological strategies.

The overall aim of this thesis was to determine the role of androgens and obesity in pregnancy and whether acupuncture could modulate placenta function and fetal growth. First, in a crosssectional study, maternal blood and placental tissue were collected at delivery from 38 women with PCOS without pregnancy complications and 40 control pregnant women to investigate signal transducer and activator of transcription 3 (STAT-3) and mechanistic target of rapamycin (mTOR) signaling pathways in placenta. Second, in rats with prenatal androgenization (PNA), we evaluated markers of steroidogenesis, angiogenesis and sympathetic activity, and we tested the hypothesis that acupuncture with low-frequency electrical stimulation prevents any alteration in the expression of those markers. Thirdly, as women with PCOS are often overweight or obese, we investigated maternal growth and metabolism, placenta weight, placenta steroid receptor expression, and liver fat content from mice exposed to maternal androgen excess with or without diet-induced maternal obesity. Moreover, we performed a global proteomic analysis in placenta and fetal liver to find novel molecules that could be involved in the observed alterations.

Pregnant women with PCOS display abnormal steroidogenic state, altered placenta gene expression of steroidogenic enzymes and molecules related to fetal growth as determined by the activation of STAT-3. Moreover, diet-induced maternal obesity and maternal androgen excess induced hepatic triglyceride accumulation and dysregulation of de novo lipogenesis in mothers. In proteomic analysis of placenta and fetal liver, we found a novel Catechol-OMethyltransferase (COMT) phosphorylation that was common in fetal liver and placenta. We also found altered gene expression of enzymes in the liver of female offspring suggesting that the sympathetic nervous system could play a role in the metabolic, reproductive or behavioral disturbances known in offspring of PCOS. These observations are supported by the finding that electroacupuncture given to pregnant dams exposed to testosterone increased systolic blood pressure, decreased fetal and placental growth and altered the expression of markers of angiogenesis, indicating an increased sympathetic nervous activity, contrary to our hypothesis.

Besides pregnancy complications, it seems that molecular signatures might make women with PCOS more sensitive and vulnerable to metabolic challenges, which potentially can explain long-term health consequences in their offspring. Moreover, it seems that the sympathetic nervous system plays an important role for fetal development in androgenized dams.