Fetal programming of polycystic ovary syndrome: Effects of androgen exposure on prenatal ovarian development

Role of the mitophagy-apoptosis axis in the pathogenesis of polycystic ovarian syndrome

AIM

Polycystic ovary syndrome (PCOS) is a common endocrine disorder characterized by menstrual irregularities, androgen excess, and polycystic ovarian morphology, but its pathogenesis remains largely unknown. This review focuses on how androgen excess influences the molecular basis of energy metabolism, mitochondrial function, and mitophagy in granulosa cells and oocytes, summarizes our current understanding of the pathogenesis of PCOS, and discuss perspectives on future research directions.

METHODS

A search of PubMed and Google Scholar databases were used to identify relevant studies for this narrative literature review.

RESULTS

Female offspring born of pregnant animals exposed to androgens recapitulates the PCOS phenotype. Abnormal mitochondrial morphology, altered expression of genes related to glycolysis, mitochondrial biogenesis, fission/fusion dynamics, and mitophagy have been identified in PCOS patients and androgenic animal models. Androgen excess causes uncoupling of the electron transport chain and depletion of the cellular adenosine 5'-triphosphate pool, indicating further impairment of mitochondrial function. A shift toward mitochondrial fission restores mitochondrial quality control mechanisms. However, prolonged mitochondrial fission disrupts autophagy/mitophagy induction due to loss of compensatory reserve for mitochondrial biogenesis. Disruption of compensatory mechanisms that mediate the quality control switch from mitophagy to apoptosis may cause a disease phenotype. Furthermore, genetic predisposition, altered expression of genes related to glycolysis and oxidative phosphorylation, or a combination of these factors may also contribute to the development of PCOS.

CONCLUSION

In conclusion, fetuses exposed to a hyperandrogenemic intrauterine environment may cause the PCOS phenotype possibly through disruption of the compensatory regulation of the mitophagy-apoptosis axis.

Preconceptional maternal hyperandrogenism and metabolic syndrome risk in male offspring: a long-term population-based study

PURPOSE

There is limited research on the effects of maternal hyperandrogenism (MHA) on cardiometabolic risk factors in male offspring. We aimed to compare the risk of metabolic syndrome (MetS) in sons of women with preconceptional hyperandrogenism (HA) to those of non-HA women in later life.

METHODS

Using data obtained from the Tehran Lipid and Glucose Cohort Study, with an average of 20 years follow-up, 1913 sons were divided into two groups based on their MHA status, sons with MHA (n = 523) and sons without MHA (controls n = 1390). The study groups were monitored from the baseline until either the incidence of events, censoring, or the end of the study period, depending on which occurred first. Age-scaled unadjusted and adjusted Cox regression models were utilized to evaluate the hazard ratios (HRs) and 95% confidence intervals (CIs) for the association between MHA and MetS in their sons.

RESULTS

There was no significant association between MHA and HR of MetS in sons with MHA compared to controls, even after adjustment (unadjusted HR (95% CI) 0.94 (0.80-1.11), P = 0.5) and (adjusted HR (95% CI) 0.98 (0.81-1.18), P = 0.8). Sons with MHA showed a HR of 1.35 for developing high fasting blood sugar compared to controls (unadjusted HR (95% CI) 1.35 (1.01-1.81), P = 0.04), however, after adjustment this association did not remain significant (adjusted HR (95% CI) 1.25 (0.90-1.74), P = 0.1).

CONCLUSION

The results suggest that preconceptional MHA doesn't increase the risk of developing MetS in sons in later life. According to this suggestion, preconceptional MHA may not have long-term metabolic consequences in male offspring.

Oocyte quality is impaired in a hyperandrogenic PCOS mouse model by increased Foxo1 expression

One of the most important characteristics of patients with polycystic ovary syndrome (PCOS) is excess androgen, which has adverse effects on pregnancy outcomes and increases the risk of offspring developing metabolic disorders. Foxo1 has been shown to play an important role in PCOS, but whether it has an affect on oocyte's quality in PCOS remains unclear. The current research investigated the effect of excess androgen exposure on mouse oocyte quality, as well as the possible molecular mechanism. Timelapse incubator was used to culture oocytes in vitro and evaluate the maturation process. The level of reactive oxygen species (ROS) and mitochondrial membrane potential were detected by laser confocal microscope. Immunofluorescence staining assays were performed to examine the expression of Foxo1 and γ-H2AX. Relative mRNA level of Foxo1 and Caspase3 were examined by RT-qPCR. Results showed Germinal vesicle breakdown and maturation rates of oocytes from hyperandrogenic PCOS mice were significantly decreased in vitro, while in vitro maturation showed a marked delay from the germinal vesicle breakdown to metaphase II stage in PCOS group. Expression levels of reactive oxygen species, Foxo1, Caspase3, and γ-H2AX were significantly increased, whereas mitochondrial membrane potential was significantly decreased in oocytes from PCOS mice. These results indicate that excess androgen exposure induced oxidative stress, which further induced high expression of Foxo1, resulting in more DNA damage and apoptosis in oocytes. The current findings provide new knowledge for exploring the mechanism of decreased oocyte quality in hyperandrogenic PCOS.

Mitochondrial Dysfunction in PCOS: Insights into Reproductive Organ Pathophysiology

Polycystic ovary syndrome (PCOS) is a complex, but relatively common endocrine disorder associated with chronic anovulation, hyperandrogenism, and micro-polycystic ovaries. In addition to reduced fertility, people with PCOS have a higher risk of obesity, insulin resistance, and metabolic disease, all comorbidities that are associated with mitochondrial dysfunction. This review summarizes human and animal data that report mitochondrial dysfunction and metabolic dysregulation in PCOS to better understand how mitochondria impact reproductive organ pathophysiology. This in-depth review considers all the elements regulating mitochondrial quantity and quality, from mitochondrial biogenesis under the transcriptional regulation of both the nuclear and mitochondrial genome to the ultrastructural and functional complexes that regulate cellular metabolism and reactive oxygen species production, as well as the dynamics that regulate subcellular interactions that are key to mitochondrial quality control. When any of these mitochondrial functions are disrupted, the energetic equilibrium within the cell changes, cell processes can fail, and cell death can occur. If this process is ongoing, it affects tissue and organ function, causing disease. The objective of this review is to consolidate and classify a broad number of PCOS studies to understand how various mitochondrial processes impact reproductive organs, including the ovary (oocytes and granulosa cells), uterus, placenta, and circulation, causing reproductive pathophysiology. A secondary objective is to uncover the potential role of mitochondria in the transgenerational transmission of PCOS and metabolic disorders.

Immune Dysfunction in Polycystic Ovary Syndrome

Polycystic ovary syndrome (PCOS) is the most common endocrine disorder in reproductive-aged individuals with ovaries. It is associated with anovulation and increased risk to fertility and metabolic, cardiovascular, and psychological health. The pathophysiology of PCOS is still inadequately understood, although there is evidence of persistent low-grade inflammation, which correlates with associated visceral obesity. Elevated proinflammatory cytokine markers and altered immune cells have been reported in PCOS and raise the possibility that immune factors contribute to ovulatory dysfunction. Because normal ovulation is modulated by immune cells and cytokines in the ovarian microenvironment, the endocrine and metabolic abnormalities associated with PCOS orchestrate the accompanying adverse effects on ovulation and implantation. This review evaluates the current literature on the relationship between PCOS and immune abnormalities, with a focus on emerging research in the field.

Maternal androgen excess increases the risk of pre-diabetes mellitus in male offspring in later life: a long-term population-based follow-up study

PURPOSE

Prenatal androgen exposure could be a source of early programming, leading to the development of cardiometabolic diseases in later life. In this study, we aimed to examine cardiometabolic disturbances in males exposed to maternal androgen excess during their prenatal life.

METHODS

In this prospective population-based study, 409 male offspring with maternal hyperandrogenism (MHA), and 954 male offspring without MHA, as controls, were included. Both groups of male offspring were followed from the baseline to the date of the incidence of events, censoring, or end of the study period, whichever came first. Age-scaled unadjusted and adjusted Cox regression models were applied to assess the hazard ratios (HR) and 95% confidence intervals (CIs) for the association between MHA with pre-diabetes mellitus (Pre-DM), type 2 diabetes mellitus (T2DM), pre-hypertension (Pre-HTN), hypertension (HTN), dyslipidemia, overweight, and obesity in the offspring of both groups. Statistical analysis was performed using the STATA software package; the significance level was set at P < 0.05.

RESULTS

A higher risk of Pre-DM (adjusted HR: 1.46 (1.20, 1.78)) was observed in male offspring with MHA after adjustment for potential confounders, including body mass index, education, and physical activity. However, no significant differences were observed in the risk of T2DM, Pre-HTN, HTN, dyslipidemia, overweight, and obesity in males with MHA compared to controls in both the unadjusted and adjusted models.

CONCLUSION

Maternal androgen excess increases the risk of Pre-DM in male offspring in later life. More longitudinal studies with long enough follow-up are needed to clarify the effects of MHA on the cardiometabolic risk factors of male offspring in later life.

Maternal nutritional status and offspring childlessness: Evidence from the late-nineteenth to early-twentieth centuries in a group of Italian populations

The role of maternal nutrition in affecting offspring fertility, through alteration of foetal programming, has been demonstrated in animal-based experiments. However, results from human populations appear inconsistent and sometimes contradictory, likely because they have been based on single famine events. In this paper, we adopt a different approach. We combine official annual time series of daily nutrient availability with a sample of women's reproductive histories from the 1961 Italian Census to investigate the role of maternal nutritional status in pregnancy on offspring childlessness. The analysis therefore covers cohorts of females born between 1861 and 1939. Our results show a negative association between calorie availability in pregnancy and the odds of offspring childlessness, whereas no association is found between protein availability and offspring childlessness. The consequences of poor calorie intake were aggravated during the summer, likely due to the participation of pregnant women in physically demanding work.

Somatic cell fate maintenance in mouse fetal testes via autocrine/paracrine action of AMH and activin B

Fate determination and maintenance of fetal testes in most mammals occur cell autonomously as a result of the action of key transcription factors in Sertoli cells. However, the cases of freemartin, where an XX twin develops testis structures under the influence of an XY twin, imply that hormonal factor(s) from the XY embryo contribute to sex reversal of the XX twin. Here we show that in mouse XY embryos, Sertoli cell-derived anti-Mullerian hormone (AMH) and activin B together maintain Sertoli cell identity. Sertoli cells in the gonadal poles of XY embryos lacking both AMH and activin B transdifferentiate into their female counterpart granulosa cells, leading to ovotestis formation. The ovotestes remain to adulthood and produce both sperm and oocytes, although there are few of the former and the latter fail to mature. Finally, the ability of XY mice to masculinize ovaries is lost in the absence of these two factors. These results provide insight into fate maintenance of fetal testes through the action of putative freemartin factors.

Ovarian expression of follicle stimulating hormone and activin receptors genes in a prenatally-androgenized rat model of polycystic ovary syndrome in adulthood

BACKGROUND

The expression of genes involved in basic pathways, such as folliculogenesis and steroidogenesis may be affected following prenatal androgen exposure. Besides, exposure to androgens during prenatal life plays a central role in developing polycystic ovary syndrome (PCOS) in females in later life. In the present study, we aimed to examine the expression of the follicle stimulating hormone receptor (FSHR) and activin receptor (actR) genes in ovarian granulosa cells (GCs) of a prenatally-androgenized rat model of PCOS in adulthood.

METHODS AND RESULTS

In the adult rat model of PCOS and their controls (n = 8 in each group), different phases of the estrous cycle were determined by vaginal smear. Total RNA was extracted from the ovarian GCs using the TRIzol protocol, a reverse transcription kit was used for complementary DNA (cDNA) synthesis, and the expression of FSHR and actR genes was measured by SYBR-Green Real-Time PCR. GraphPad Prism was used for statistical analysis of data, and the t-Student's test was used to compare the results between the two groups. PCOS rats had longer and irregular estrous cycles compared to controls. The expression of FSHR and actR genes were significantly decreased in the rat model of PCOS compared to control rats. In PCOS rats, genes expression ratios for FSHR and actR were 0.91 ± 0.11 times (P = 0.008) and 0.42 ± 0.13 times (P = 0.048) less than controls, respectively.

CONCLUSION

Reduced expression of the FSHR and actR genes in ovarian GCs may be one of the mechanisms mediating PCOS-related disorders, especially abnormal ovarian folliculogenesis and ovulation dysfunction, following exposure to androgens during fetal life.

Pathology of hyperandrogenemia in the oocyte of polycystic ovary syndrome

Polycystic ovary syndrome (PCOS) is the most common ovulatory disorder in the world and is associated with multiple adverse outcomes. The phenotype is widely varied, with several pathologies contributing to the spectrum of the disease including insulin resistance, obesity and hyperandrogenemia. Of these, the role of hyperandrogenemia and the mechanism by which it causes dysfunction remains poorly understood. Early studies have shown that androgens may affect the metabolic pathways of a cell, and this may pose hazards at the level of the mitochondria. As mitochondria are strictly maternally inherited, this would provide an exciting explanation not only to the pathophysiology of PCOS as a disease, but also to the inheritance pattern. This review seeks to summarize what is known about PCOS and associated adverse outcomes with focus on the role of hyperandrogenemia and specific emphasis on the oocyte.

Maternal low protein diet and fetal programming of lean type 2 diabetes

Maternal nutrition is found to be the key factor that determines fetal health in utero and metabolic health during adulthood. Metabolic diseases have been primarily attributed to impaired maternal nutrition during pregnancy, and impaired nutrition has been an immense issue across the globe. In recent years, type 2 diabetes (T2D) has reached epidemic proportion and is a severe public health problem in many countries. Although plenty of research has already been conducted to tackle T2D which is associated with obesity, little is known regarding the etiology and pathophysiology of lean T2D, a variant of T2D. Recent studies have focused on the effects of epigenetic variation on the contribution of in utero origins of lean T2D, although other mechanisms might also contribute to the pathology. Observational studies in humans and experiments in animals strongly suggest an association between maternal low protein diet and lean T2D phenotype. In addition, clear sex-specific disease prevalence was observed in different studies. Consequently, more research is essential for the understanding of the etiology and pathophysiology of lean T2D, which might help to develop better disease prevention and treatment strategies. This review examines the role of protein insufficiency in the maternal diet as the central driver of the developmental programming of lean T2D.