Melatonin stimulates aromatase expression and estradiol production in human granulosa-lutein cells: relevance for high serum estradiol levels in patients with ovarian hyperstimulation syndrome

Effect of TSH on aromatase expression of ovarian granulosa cells in obese mice

PURPOSE

Aromatase plays an important role in ovarian development, the normal progress of the menstrual cycle, and fertility status. Elevated aromatase activity is linked to obesity. There is a bidirectional relationship between obesity and thyroid function. Few studies have investigated the relationship between TSH and ovarian aromatase in obesity. Our aim was to investigate the effect of TSH on aromatase expression of ovarian granulosa cells in obese mice.

METHODS

Female mice pups were divided into an obesity group and a control group. Obese parameters and the time of pubertal onset were recorded. At the age of 5 weeks, blood and tissues were obtained. Serum aromatase and hormone concentrations were measured using ELISA. The granulosa cells were isolated and exposed to variable concentrations (0 μM, 1 μM, 10 μM, 100 μM) of TSH. The expression of CYP19A1 mRNA and protein were assessed via RT-qPCR and western blot.

RESULTS

In female mice, body weight, Lee's obesity index, and serum levels of E2, aromatase, and TSH were significantly higher in the obesity group compared to the control group, whereas the time of pubertal onset and serum T3 and T4 concentrations were significantly lower (all P < 0.001). In granulosa cells, the expression of CYP19A1 mRNA in the obesity group was lower than that in the control group at 1 μM and 100 μM concentrations of TSH (both P < 0.001). The expression of CYP19A1 protein in the obesity group was higher than that in the control group after TSH stimulation (P = 0.014, P < 0.001, and P = 0.004, respectively). With the increase of TSH concentrations, the expression of CYP19A1 mRNA and protein in the two groups significantly increased (all P < 0.001).

CONCLUSION

Early puberty and elevated serum aromatase and TSH levels were found in obese female mice. In the granulosa cells of obese mice, TSH directly regulates aromatase expression in a dose-dependent manner.

Melatonin protects oogenesis from hypobaric hypoxia-induced fertility damage in mice

Environmental hypoxia adversely affects reproductive health in humans and animals at high altitudes. Therefore, how to alleviate the follicle development disorder caused by hypoxia exposure and to improve the competence of fertility in plateau non-habituated female animals are important problems to be solved urgently. In this study, a hypobaric hypoxic chamber was used for 4 weeks to simulate hypoxic conditions in female mice, and the effects of hypoxia on follicle development, proliferation and apoptosis of granulosa cells, reactive oxygen species (ROS) levels in MII oocyte and 2-cell rate were evaluated. At the same time, the alleviating effect of melatonin on hypoxic exposure-induced oogenesis damage was evaluated by feeding appropriate amounts of melatonin daily under hypoxia for 4 weeks. The results showed that hypoxia exposure significantly increased the proportion of antral follicles in the ovary, the number of proliferation and apoptosis granulosa cells in the follicle, and the level of ROS in MII oocytes, eventually led to the decline of oocyte quality. However, these defects were alleviated when melatonin was fed under hypoxia conditions. Together, these findings suggest that hypoxia exposure impaired follicular development and reduced oocyte quality, and that melatonin supplementation alleviated the fertility reduction induced by hypoxia exposure.

Vitamin D3 reduces the symptoms of ovarian hyperstimulation syndrome in mice and inhibits the release of granulosa cell angiogenic factor through pentraxin 3

It has been reported that the effective inhibition of vascular endothelial growth factor (VEGF) can prevent the progression of ovarian hyperstimulation syndrome (OHSS). The present study aimed to investigate the mechanism underlying the effect of vitamin D3 (VD3) on OHSS in mouse models and granulosa cells. The effects of VD3 administration (16 and 24 IU) on ovarian permeability were determined using Evans blue. In addition, ovarian pathology, corpus luteum count, inflammatory responses, and hormone and VEGFA levels were assessed using pathological sections and ELISA. Molecular docking predicted that pentraxin 3 (PTX3) could be a potential target of VD3, and therefore, the effects of human chorionic gonadotropin (hCG) and VD3 as well as PTX3 overexpression on the production and secretion of VEGFA in granulosa cells were also investigated using western blotting and immunofluorescence. Twenty-four IU VD3 significantly reversed the increase in ovarian weight and permeability in mice with OHSS. Additionally, VD3 diminished congestion and the number of corpus luteum in the ovaries and reduced the secretion levels of inflammatory factors and those of estrogen and progesterone. Notably, VD3 downregulated VEGFA and CD31 in ovarian tissues, while the expression levels of PTX3 varied among different groups. Furthermore, VD3 restored the hCG-induced enhanced VEGFA and PTX3 expression levels in granulosa cells, whereas PTX3 overexpression abrogated the VD3-mediated inhibition of VEGFA production and secretion. The present study demonstrated that VD3 could inhibit the release of VEGFA through PTX3, thus supporting the beneficial effects of VD3 administration on ameliorating OHSS symptoms.

TGF-β1 and TGF-β3, but not TGF-β2, are upregulated in the ovaries of ovarian hyperstimulation syndrome†

Ovarian hyperstimulation syndrome (OHSS) is a life-threatening and potentially fatal complication during in vitro fertilization treatment. The levels of transforming growth factor-β1 (TGF-β1) are upregulated in human follicular fluid and granulosa-lutein cells (hGL) of OHSS patients and could contribute to the development of OHSS by downregulating steroidogenic acute regulatory protein (StAR) expression. However, whether the same is true for the other two members of the TGF-β family, TGF-β2 and -β3, remains unknown. We showed that all three TGF-β isoforms were expressed in human follicular fluid. In comparison, TGF-β1 was expressed at the highest level, followed by TGF-β2 and TGF-β3. Compared to non-OHSS patients, follicular fluid levels of TGF-β1 and TGF-β3 were significantly upregulated in OHSS patients. The same results were observed in mRNA levels of TGF-β isoforms in hGL cells and ovaries of OHSS rats. In addition, StAR mRNA levels were upregulated in hGL cells of OHSS patients and the ovaries of OHSS rats. Treatment cells with TGF-β isoforms downregulated the StAR expression with a comparable effect. Moreover, activations of SMAD3 signaling were required for TGF-β isoforms-induced downregulation of StAR expression. This study indicates that follicular fluid TGF-β1 and TGF-β3 levels could be used as biomarkers and therapeutic targets for the OHSS.

TGF-β1 upregulates secreted protein acidic and rich in cysteine expression in human granulosa-lutein cells: a potential mechanism for the pathogenesis of ovarian hyperstimulation syndrome

BACKGROUND

Ovarian hyperstimulation syndrome (OHSS) is a serious complication during in vitro fertilization (IVF) treatment. The upregulation of ovarian transforming growth factor-beta 1 (TGF-β1) is involved in the development of OHSS. The secreted protein acidic and rich in cysteine (SPARC) is a secreted multifunctional matricellular glycoprotein. Although the regulatory effects of TGF-β1 on SPARC expression have been reported, whether TGF-β1 regulates SPARC expression in the human ovary remains unknown. In addition, the role of SPARC in the pathogenesis of OHSS is unclear.

METHODS

A steroidogenic human ovarian granulosa-like tumor cell line, KGN, and primary culture of human granulosa-lutein (hGL) cells obtained from patients undergoing IVF treatment were used as experimental models. OHSS was induced in rats, and ovaries were collected. Follicular fluid samples were collected from 39 OHSS and 35 non-OHSS patients during oocyte retrieval. The underlying molecular mechanisms mediating the effect of TGF-β1 on SPARC expression were explored by a series of in vitro experiments.

RESULTS

TGF-β1 upregulated SPARC expression in both KGN and hGL cells. The stimulatory effect of TGF-β1 on SPARC expression was mediated by SMAD3 but not SMAD2. The transcription factors, Snail and Slug, were induced in response to the TGF-β1 treatment. However, only Slug was required for the TGF-β1-induced SPARC expression. Conversely, we found that the knockdown of SPARC decreased Slug expression. Our results also revealed that SPARC was upregulated in the OHSS rat ovaries and in the follicular fluid of OHSS patients. Knockdown of SPARC attenuated the TGF-β1-stimulated expression of vascular endothelial growth factor (VEGF) and aromatase, two markers of OHSS. Moreover, the knockdown of SPARC reduced TGF-β1 signaling by downregulating SMAD4 expression.

CONCLUSIONS

By illustrating the potential physiological and pathological roles of TGF-β1 in the regulation of SPARC in hGL cells, our results may serve to improve current strategies used to treat clinical infertility and OHSS. Video Abstract.

Pathophysiological Effects of Contemporary Lifestyle on Evolutionary-Conserved Survival Mechanisms in Polycystic Ovary Syndrome

Polycystic ovary syndrome (PCOS) is increasingly being characterized as an evolutionary mismatch disorder that presents with a complex mixture of metabolic and endocrine symptoms. The Evolutionary Model proposes that PCOS arises from a collection of inherited polymorphisms that have been consistently demonstrated in a variety of ethnic groups and races. In utero developmental programming of susceptible genomic variants are thought to predispose the offspring to develop PCOS. Postnatal exposure to lifestyle and environmental risk factors results in epigenetic activation of developmentally programmed genes and disturbance of the hallmarks of health. The resulting pathophysiological changes represent the consequences of poor-quality diet, sedentary behaviour, endocrine disrupting chemicals, stress, circadian disruption, and other lifestyle factors. Emerging evidence suggests that lifestyle-induced gastrointestinal dysbiosis plays a central role in the pathogenesis of PCOS. Lifestyle and environmental exposures initiate changes that result in disturbance of the gastrointestinal microbiome (dysbiosis), immune dysregulation (chronic inflammation), altered metabolism (insulin resistance), endocrine and reproductive imbalance (hyperandrogenism), and central nervous system dysfunction (neuroendocrine and autonomic nervous system). PCOS can be a progressive metabolic condition that leads to obesity, gestational diabetes, type two diabetes, metabolic-associated fatty liver disease, metabolic syndrome, cardiovascular disease, and cancer. This review explores the mechanisms that underpin the evolutionary mismatch between ancient survival pathways and contemporary lifestyle factors involved in the pathogenesis and pathophysiology of PCOS.

High and low dose of luzindole or 4-phenyl-2-propionamidotetralin (4-P-PDOT) reverse bovine granulosa cell response to melatonin

Background

Communication between oocytes and granulosa cells ultimately dictate follicle development or atresia. Melatonin is also involved in follicle development. This study aimed to investigate the effects of melatonin and its receptor antagonists on hormone secretion, as well as gene expression related to hormone synthesis, TGF-β superfamily, and follicle development in bovine granulosa cells, and assess the effects of melatonin in the presence of 4-P-PDOT and luzindole.

Methods

Bovine ovaries were collected from a local abattoir and follicular fluid (follicle diameter 5-8 mm) was collected for granulosa cell isolation and culture. Granulosa cells and culture medium were collected 48 h after treatment with melatonin at high dose concentrations (10^-5 M) and low dose concentrations (10^-9 M) in the absence/presence of 4-P-PDOT and luzindole (10^-5 M or 10^-9 M). Furthermore, the expression level of genes related to hormonal synthesis (CYP11A1, CYP19A1, StAR, and RUNX2), TGF-β superfamily (BMP6, INHA, INHBA, INHBB, and TGFBR3), and development (EGFR, DNMT1A, and FSHR) were detected in each experimental group by real-time quantitative PCR. In addition, the level of hormones in culture medium were detected using ELISA.

Results

Both 10^-5 M and 10^-9 M melatonin doses promoted the secretion of inhibin A and progesterone without affecting the production of inhibin B and estradiol. In addition, both promoted the gene expression of INHA, StAR, RUNX2, TGFBR3, EGFR, and DNMT1A, and inhibited the expression of BMP6, INHBB, CYP11A1, CYP19A1, and FSHR. When combined with different doses of 4-P-PDOT and luzindole, they exhibited different effects on the secretion of inhibin B, estradiol, inhibin A, and progesterone, and the expression of CYP19A1, RUNX2, BMP6, INHBB, EGFR, and DNMT1A induced by melatonin.

Conclusion

High and low dose melatonin receptor antagonists exhibited different effects in regulating hormone secretion and the expression of various genes in response to melatonin. Therefore, concentration effects must be considered when using luzindole or 4-P-PDOT.

Biomarkers identification in follicular fluid of women with OHSS by using UPLC-MS method

To figure out the differentially changed metabolites and disturbed pathways in follicular fluid (FF) of patients with OHSS in comparison to the control group undergoing in vitro fertilization (IVF), we conducted this metabolomic analysis between two groups, the OHSS group included 30 patients treated with oocyte retrieval and developed OHSS in the next 7-14 days, while another 30 patients without OHSS tendency were selected as the control group. The FF samples were obtained during the process of oocyte retrieval. FF samples were analyzed using ultra-high liquid chromatography-tandem mass spectrometry (UPLC-MS). The results identified a total of 59 differentially changed metabolites, including 33 decreased metabolites (P < 0.01) and 26 increased metabolites (P < 0.01) in FF of OHSS compared with the control group. 12 metabolites could be the most valuable biomarkers for OHSS based on ROC results. Our correlation analyses showed that deoxyinosine levels were found positively correlated with serum estradiol (E2) levels in OHSS patients, while L-isoleucine, pyruvic acid, maleamate, and arachidonic acid were found to be positively correlated with the number of retrieved oocytes. Furthermore, 4-hydroxyphenylacetaldehyde, deoxycorticosterone, creatinine, and creatine were found to be negatively associated with serum E2 levels, while 4-hydroxyphenylacetaldehyde, L-carnitine, isovaleric acid and L-2-hydroxyglutaric acid were negatively related with the number of oocytes retrieved in OHSS patients. Taken together, our study provides better identification of OHSS FF metabolic dynamics, suggesting the metabolic compounds can be used as valuable predictors or treatment targets of OHSS.

Melatonin Mitigates Cisplatin-Induced Ovarian Dysfunction via Altering Steroidogenesis, Inflammation, Apoptosis, Oxidative Stress, and PTEN/PI3K/Akt/mTOR/AMPK Signaling Pathway in Female Rats

Ovarian damage and fertility impairment are major side effects of chemotherapy in pre-menopausal cancer patients. Cisplatin is a widely used chemotherapeutic drug. The present study was designed to assess the ameliorative effects of melatonin as an adjuvant for fertility preservation. Thirty-two adult female Wistar rats were divided randomly into four equal groups: Control, Melatonin, Cisplatin (CP) treated, and CP + Melatonin treated. The cisplatin-treated group showed decreased body and ovarian weights, decreased serum E2 and AMH, increased serum LH and FSH, reduced ovarian levels of SOD, CAT, GSH, and TAC, and increased ovarian MDA. The histopathological examination of the cisplatin-treated group showed deleterious changes within ovarian tissue in the form of damaged follicles and corpus luteum, hemorrhage, and inflammatory infiltrates with faint PAS reaction in zona pellucida, increased ovarian collagen deposition, and marked expression of caspase-3 immune reaction in granulosa and theca cells, stroma, and oocytes. Alongside, there was a significant downregulation in the mRNA expression of steroidogenic enzymes, IL10, AMPK, PI3K, AKT, mTOR, and PTEN, while TGF-β1, IL1β, IL6, TNF-α, NF-Kβ, P53, p38-MAPK, JNK, and FOXO3 mRNA expressions were upregulated in cisplatin-treated rats' ovarian tissue. Coadministration of cisplatin-treated rats with melatonin reversed these changes significantly. In conclusion, melatonin's antioxidant, anti-inflammatory, and anti-apoptotic activities could modulate ovarian disturbances induced by cisplatin and preserve fertility.

Melatonin in Endometriosis: Mechanistic Understanding and Clinical Insight

Endometriosis is defined as the development of endometrial glands and stroma outside the uterine cavity. Pathophysiology of this disease includes abnormal hormone profiles, cell survival, migration, invasion, angiogenesis, oxidative stress, immunology, and inflammation. Melatonin is a neuroendocrine hormone that is synthesized and released primarily at night from the mammalian pineal gland. Increasing evidence has revealed that melatonin can be synthesized and secreted from multiple extra-pineal tissues where it regulates immune response, inflammation, and angiogenesis locally. Melatonin receptors are expressed in the uterus, and the therapeutic effects of melatonin on endometriosis and other reproductive disorders have been reported. In this review, key information related to the metabolism of melatonin and its biological effects is summarized. Furthermore, the latest in vitro and in vivo findings are highlighted to evaluate the pleiotropic functions of melatonin, as well as to summarize its physiological and pathological effects and treatment potential in endometriosis. Moreover, the pharmacological and therapeutic benefits derived from the administration of exogenous melatonin on reproductive system-related disease are discussed to support the potential of melatonin supplements toward the development of endometriosis. More clinical trials are needed to confirm its therapeutic effects and safety.

Environmental disruption of reproductive rhythms

Reproduction is a key biological function requiring a precise synchronization with annual and daily cues to cope with environmental fluctuations. Therefore, humans and animals have developed well-conserved photoneuroendocrine pathways to integrate and process daily and seasonal light signals within the hypothalamic-pituitary-gonadal axis. However, in the past century, industrialization and the modern 24/7 human lifestyle have imposed detrimental changes in natural habitats and rhythms of life. Indeed, exposure to an excessive amount of artificial light at inappropriate timing because of shift work and nocturnal urban lighting, as well as the ubiquitous environmental contamination by endocrine-disrupting chemicals, threaten the integrity of the daily and seasonal timing of biological functions. Here, we review recent epidemiological, field and experimental studies to discuss how light and chemical pollution of the environment can disrupt reproductive rhythms by interfering with the photoneuroendocrine timing system.

Effects of Melatonin on the Transcriptome of Human Granulosa Cells, Fertilization and Blastocyst Formation

Melatonin is a promising reagent that can improve assisted reproductive technology (ART) outcomes in infertility patients. However, melatonin is not effective for all infertile patients, and it remains unclear for which patients melatonin would be effective. This study examined the effects of melatonin on ART outcomes and examined its mechanisms. Melatonin increased the fertilization rate in patients whose fertilization rates in the previous cycle were less than 50%, but not in patients whose fertilization rates were more than 50% in the previous cycle. Melatonin increased the blastocyst formation rate in patients whose embryo development rates in the previous cycle were less than 50%, but not in patients whose embryo development rates were more than 50% in the previous cycle. To clarify its mechanisms, transcriptome changes by melatonin treatment in granulosa cells (GCs) of the patients were examined by RNA-sequence. Melatonin treatment altered the transcriptomes of GCs of patients with poor ART outcomes so that they were similar to the transcriptomes of patients with good ART outcomes. The altered genes were associated with the inhibition of cell death and T-cell activity, and the activation of steroidogenesis and angiogenesis. Melatonin treatment was effective for patients with poor fertilization rates and poor embryo development rates in the previous ART cycle. Melatonin alters the GCs transcriptome and, thus, their functions, and this could improve the oocyte quality, leading to good ART outcomes.

Growth differentiation factor-11 downregulates steroidogenic acute regulatory protein expression through ALK5-mediated SMAD3 signaling pathway in human granulosa-lutein cells

BACKGROUND

Growth differentiation factor-11 (GDF-11) belongs to the transforming growth factor-β (TGF-β) superfamily. To date, the expression of GDF-11 in the ovary and its role in regulating ovarian function are completely unknown. Ovarian granulosa cell-mediated steroidogenesis plays a pivotal role in maintaining normal female reproductive function. GDF-11 and GDF-8 share high sequence similarity and exhibit many similar features and functions. Steroidogenic acute regulatory protein (StAR) regulates the rate-limiting step in steroidogenesis and its expression can be downregulated by GDF-8. Polycystic ovary syndrome (PCOS) is the most common cause of female infertility. The expression levels of GDF-8 are upregulated in the human follicular fluid and granulosa-lutein (hGL) cells of PCOS patients. However, whether similar results can be observed for the GDF-11 needs to be determined.

METHODS

The effect of GDF-11 on StAR expression and the underlying molecular mechanisms were explored by a series of in vitro experiments in a primary culture of hGL cells obtained from patients undergoing in vitro fertilization (IVF) treatment. Human follicular fluid samples were obtained from 36 non-PCOS patients and 36 PCOS patients. GDF-11 levels in follicular fluid were measured by ELISA.

RESULTS

GDF-11 downregulates StAR expression, whereas the expression levels of the P450 side-chain cleavage enzyme (P450scc) and 3β-hydroxysteroid dehydrogenase (3β-HSD) are not affected by GDF-11 in hGL cells. Using pharmacological inhibitors and a siRNA-mediated approach, we reveal that ALK5 but not ALK4 mediates the suppressive effect of GDF-11 on StAR expression. Although GDF-11 activates both SMAD2 and SMAD3 signaling pathways, only SMAD3 is involved in the GDF-11-induced downregulation of StAR expression. In addition, we show that SMAD1/5/8, ERK1/2, and PI3K/AKT signaling pathways are not activated by GDF-11 in hGL cells. RT-qPCR and ELISA detect GDF-11 mRNA expression in hGL cells and GDF-11 protein expression in human follicular fluid, respectively. Interestingly, unlike GDF-8, the expression levels of GDF-11 are not varied in hGL cells and follicular fluid between non-PCOS and PCOS patients.

CONCLUSIONS

This study increases the understanding of the biological function of GDF-11 and provides important insights into the regulation of ovarian steroidogenesis.

High ovarian GDF-8 levels contribute to elevated estradiol production in ovarian hyperstimulation syndrome by stimulating aromatase expression

Rationale: Growth differentiation factor-8 (GDF-8), also known as myostatin, belongs to the transforming growth factor-beta (TGF-β) superfamily. GDF-8 is expressed in the ovary and regulates various ovarian functions. Ovarian hyperstimulation syndrome (OHSS) is one of the most serious disorders during in vitro fertilization treatment. Aromatase, encoded by the CYP19A1 gene, is the enzyme that catalyzes the final step in estradiol (E2) biosynthesis. It has been demonstrated that high serum E2 levels are associated with the development of OHSS. However, the effects of GDF-8 on aromatase expression and its roles in the pathogenesis of OHSS remain unclear. Methods: The effect of GDF-8 on aromatase expression and the underlying mechanisms were explored by a series of in vitro experiments in primary human granulosa-lutein (hGL) and KGN cells. Rat OHSS model and human follicular fluid samples were used to examine the roles of the GDF-8 system in the pathogenesis of OHSS. Results: We demonstrate that GDF-8 stimulates aromatase expression and E2 production in hGL and KGN cells. In addition, TGF-β type I receptor ALK5-mediated SMAD2/3 signaling is required for GDF-8-induced aromatase expression and E2 production. Using a rat OHSS model, we show that the aromatase and GDF-8 levels are upregulated in the ovaries of OHSS rats. Blocking the function of ALK5 by the administration of its inhibitor, SB431542, alleviates OHSS symptoms and the upregulation of aromatase. Clinical results reveal that the protein levels of GDF-8 are upregulated in the follicular fluid of OHSS patients. Moreover, the expression of GDF-8 is increased in hGL cells of OHSS patients. Conclusions: This study helps to elucidate the mechanisms mediating the expression of aromatase in human granulosa cells, which may lead to the development of alternative therapeutic approaches for OHSS.

TGF-β1 stimulates aromatase expression and estradiol production through SMAD2 and ERK1/2 signaling pathways in human granulosa-lutein cells

Estradiol (E2), one of the main steroid hormones secreted by the ovaries, plays an important role in maintaining normal female reproductive function. Ovarian granulosa cells are the main source of E2 production because these cells express aromatase, which is encoded by the CYP19A1 gene and catalyzes the final step in E2 biosynthesis from androgens. Transforming growth factor-beta 1 (TGF-β1) and its receptors are expressed in human granulosa cells, and TGF-β1 expression can be detected in human follicular fluid. To date, TGF-β1 has been shown to regulate various ovarian functions. However, whether aromatase can be regulated by TGF-β1 in human granulosa cells has not been determined. In the present study, we demonstrate that TGF-β1 stimulates aromatase expression in primary human granulosa-lutein cells and in the human ovarian granulose-like tumor cell line, KGN. We used pharmacological inhibitors and small interfering RNA-mediated knockdown approaches to reveal that the SMAD2 and ERK1/2 signaling pathways are involved in TGF-β1-induced aromatase expression and E2 production. These results not only provide important insights into the molecular mechanisms that mediate TGF-β1-induced aromatase expression and E2 production in human granulosa cells but also increase the understanding of the normal physiological roles of TGF-β1 in the ovary.