Polycystic ovary syndrome (PCOS) is a disorder characterized by hyperandrogenism and chronic anovulation. Although the etiology of PCOS is unknown, perturbations of gonadotropin secretion are one of the hallmarks of this disorder. In normal menstrual physiology, the monotropic rise of plasma follicle-stimulating hormone (FSH) during the luteal-follicular transition is critical for follicular development and subsequent ovulation. One of the mechanisms by which FSH is differentially synthesized involves the luteal slowing of gonadotropin-releasing hormone (GnRH) pulse frequency by ovarian steroids. In PCOS, plasma leutinizing hormone (LH) is commonly increased, FSH is typically in the lower follicular range, and LH (and by inference GnRH) pulse frequency is persistently rapid at approximately one LH pulse per hour. The etiology of the neuroendocrine abnormalities in PCOS remain unclear; however, recent studies have revealed decreased sensitivity of the GnRH pulse generator to inhibition by ovarian steroids, particularly progesterone. This abnormality is reversed by the androgen receptor antagonist flutamide, suggesting that elevated androgen levels may alter the sensitivity of the hypothalamic GnRH pulse generator to steroid inhibition and lead to enhanced LH secretion. As such, women with PCOS require higher levels of progesterone to slow the frequency of GnRH pulse secretion, resulting in inadequate FSH synthesis and persistent LH stimulation of ovarian androgens. The decreased sensitivity of the GnRH pulse generator may help to explain the genesis of PCOS during puberty. In normal early puberty, sleep-entrained increases in LH stimulate ovarian steroids, which subsequently suppress LH frequency and amplitude during the subsequent day. In hyperandrogenemic girls destined to develop PCOS, this nocturnal increase in ovarian steroids may not be adequate to suppress the GnRH pulse generator, leading to a persistently rapid LH pulse frequency, impaired FSH production, and inadequate follicular development.
PMID 12536355 12536355 DOI 10.1055/s-2002-36706 10.1055/s-2002-36706 McCartney et al. 2003, McCartney 2003
Cite this article
McCartney, C. R., Eagleson, C. A., & Marshall, J. C. (2002). Regulation of gonadotropin secretion: implications for polycystic ovary syndrome. Seminars in reproductive medicine, 20(4), 317-326. https://doi.org/10.1055/s-2002-36706
McCartney CR, Eagleson CA, Marshall JC. Regulation of gonadotropin secretion: implications for polycystic ovary syndrome. Semin Reprod Med. 2002;20(4):317-326. doi:10.1055/s-2002-36706
McCartney, C. R., et al. "Regulation of gonadotropin secretion: implications for polycystic ovary syndrome." Seminars in reproductive medicine, vol. 20, no. 4, 2002, pp. 317-326.
Polycystic ovary syndrome (PCOS) is a highly prevalent endocrine disorder associated with hyperandrogenism and anovulation. Although a spectrum disorder, many women with PCOS exhibit elevated luteinizing hormone (LH) pulse frequency and an elevated LH to follicle stimulating hormone ratio. This aberrant pattern of gonadotrophin signalling drives many of the downstream ovarian features of PCOS, including increased androgen synthesis, and indicates neuroendocrine impairments upstream. Decreased responsiveness to gonadal steroid hormone negative feedback in PCOS patients points toward dysfunction within the gonadotropin-releasing hormone (GnRH) neuronal network in the brain. Excessive androgen exposure during development or over pubertal onset can recapitulate the neuroendocrine pathology of PCOS in pre-clinical models, and these models have been fundamental in beginning to pick apart the specific central mechanisms involved. This mini-review will briefly describe the pathology of PCOS associated with high frequency GnRH/LH pulses and then highlight what is currently known, and yet to be discovered, about the central mechanisms involved.
The present study investigated the role of melatonin (MT) in regulating mitochondrial function via sirtuin 3 (SIRT3) in granulosa cells (GCs) from patients with polycystic ovary syndrome (PCOS), with a focus on mitochondrial protection. Notably, GCs isolated from patients with PCOS exhibited mitochondrial dysfunction. Using an in vitro PCOS model established by treating KGN cells with dihydrotestosterone (DHT), decreased SIRT3 expression, dysregulated mitochondrial dynamics and hyperactivation of mitophagy were observed. Both SIRT3 overexpression and MT treatment restored the mitochondrial membrane potential, rebalanced mitochondrial dynamics and suppressed excessive autophagy in DHT-treated cells. Additionally, MT levels were shown to be reduced in the follicular fluid of patients with PCOS. Notably, the protective effects of MT on proteins associated with both mitochondrial dynamics and autophagy were abolished upon SIRT3 inhibition. In conclusion, mitochondrial dysfunction and aberrant mitophagy in GCs may serve a role in the pathogenesis of PCOS. MT appears to ameliorate these defects by modulating mitochondrial dynamics and function in a SIRT3-dependent manner. Moreover, the current study identified SIRT3 as a key molecular target of MT in PCOS.
Polycystic ovarian syndrome (PCOS) is a metabolic, reproductive, and psychological complex series of disorders that impacts a woman throughout her lifespan. PCOS is a disorder of hormonal imbalance occurring in women of reproductive age. This disorder is characterized by high levels of male androgens like testosterone. This can lead to symptoms like irregular periods, amenorrhea (absence of menstruation), anovulation (absence of ovulation), hirsutism, acne, and obesity. PCOS also causes metabolic impairment. Multiple peripherally arranged immature follicles of about 2-5mm in diameter are present in the ovary. These follicles do not mature due to hormonal imbalances leading to an irregular menstrual cycle. PCOS is a metabolic, reproductive, and psychological complex series of disorders that impacts a woman throughout her lifespan. Polycystic ovarian syndrome is not a fatal or life-threatening disorder as its main complication is infertility. PCOS can be a root cause of serious medical conditions like obesity, hypertension, type-2 diabetes mellitus due to insulin resistance, endometrial cancers, ovarian cancer, etc. Stress may cause the hormone levels in the pituitary to fluctuate. Since the menstrual cycle is hormone-based, there are apparent irregularities.
Polycystic ovary syndrome (PCOS) is the main cause of female infertility worldwide and corresponds with a high degree of comorbidities and economic burden. How PCOS is passed on from one generation to the next is not clear, but it may be a developmental condition. Most women with PCOS exhibit higher levels of circulating luteinizing hormone, suggestive of heightened gonadotropin-releasing hormone (GnRH) release, and anti-Müllerian hormone (AMH) as compared to healthy women. Excess AMH in utero may affect the development of the female fetus. However, as AMH levels drop during pregnancy in women with normal fertility, it was unclear whether their levels were also elevated in pregnant women with PCOS. Here we measured AMH in a cohort of pregnant women with PCOS and control pregnant women and found that AMH is significantly more elevated in the former group versus the latter. To determine whether the elevation of AMH during pregnancy in women with PCOS is a bystander effect or a driver of the condition in the offspring, we modeled our clinical findings by treating pregnant mice with AMH and followed the neuroendocrine phenotype of their female progeny postnatally. This treatment resulted in maternal neuroendocrine-driven testosterone excess and diminished placental metabolism of testosterone to estradiol, resulting in a masculinization of the exposed female fetus and a PCOS-like reproductive and neuroendocrine phenotype in adulthood. We found that the affected females had persistently hyperactivated GnRH neurons and that GnRH antagonist treatment in the adult female offspring restored their neuroendocrine phenotype to a normal state. These findings highlight a critical role for excess prenatal AMH exposure and subsequent aberrant GnRH receptor signaling in the neuroendocrine dysfunctions of PCOS, while offering a new potential therapeutic avenue to treat the condition during adulthood.