Hyperandrogenemia Induced by Letrozole Treatment of Pubertal Female Mice Results in Hyperinsulinemia Prior to Weight Gain and Insulin Resistance

Targeted inhibition of kisspeptin neurons reverses hyperandrogenemia and abnormal hyperactive LH secretion in a preclinical mouse model of polycystic ovary syndrome

STUDY QUESTION

Do hyperactive kisspeptin neurons contribute to abnormally high LH secretion and downstream hyperandrogenemia in polycystic ovary syndrome (PCOS)-like conditions and can inhibition of kisspeptin neurons rescue such endocrine impairments?

SUMMARY ANSWER

Targeted inhibition of endogenous kisspeptin neuron activity in a mouse model of PCOS reduced the abnormally hyperactive LH pulse secretion and hyperandrogenemia to healthy control levels.

WHAT IS KNOWN ALREADY

PCOS is a reproductive disorder characterized by hyperandrogenemia, anovulation, and/or polycystic ovaries, along with a hallmark feature of abnormal LH hyper-pulsatility, but the mechanisms underlying the endocrine impairments remain unclear. A chronic letrozole (LET; aromatase inhibitor) mouse model recapitulates PCOS phenotypes, including polycystic ovaries, anovulation, high testosterone, and hyperactive LH pulses. LET PCOS-like females also have increased hypothalamic kisspeptin neuronal activation which may drive their hyperactive LH secretion and hyperandrogenemia, but this has not been tested.

STUDY DESIGN, SIZE, DURATION

Transgenic KissCRE+/hM4Di female mice or littermates Cre- controls were treated with placebo, or chronic LET (50 µg/day) to induce a PCOS-like phenotype, followed by acute (once) or chronic (2 weeks) clozapine-N-oxide (CNO) exposure to chemogenetically inhibit kisspeptin cells (n = 6 to 10 mice/group).

PARTICIPANTS/MATERIALS, SETTING, METHODS

Key endocrine measures, including in vivo LH pulse secretion patterns and circulating testosterone levels, were assessed before and after selective kisspeptin neuron inhibition and compared between PCOS groups and healthy controls. Alterations in body weights were measured and pituitary and ovarian gene expression was determined by qRT-PCR.

MAIN RESULTS AND THE ROLE OF CHANCE

Acute targeted inhibition of kisspeptin neurons in PCOS mice successfully lowered the abnormally hyperactive LH pulse secretion (P < 0.05). Likewise, chronic selective suppression of kisspeptin neuron activity reversed the previously high LH and testosterone levels (P < 0.05) down to healthy control levels and rescued reproductive gene expression (P < 0. 05).

LARGE SCALE DATA

N/A.

LIMITATIONS, REASONS FOR CAUTION

Ovarian morphology was not assessed in this study. Additionally, mouse models can offer mechanistic insights into neuroendocrine processes in PCOS-like conditions but may not perfectly mirror PCOS in women.

WIDER IMPLICATIONS OF THE FINDINGS

These data support the hypothesis that overactive kisspeptin neurons can drive neuroendocrine PCOS-like impairments, and this may occur in PCOS women. Our findings complement recent clinical investigations using NKB receptor antagonists to lower LH in PCOS women and suggest that pharmacological dose-dependent modulation of kisspeptin neuron activity may be a valuable future therapeutic target to clinically treat hyperandrogenism and lower elevated LH in PCOS women.

STUDY FUNDING/COMPETING INTEREST(S)

This research was supported by NIH grants R01 HD111650, R01 HD090161, R01 HD100580, P50 HD012303, R01 AG078185, and NIH R24 HD102061, and a pilot project award from the British Society for Neuroendocrinology. There are no competing interests.

Hyperandrogenemia elevates expression of apelin and apelin receptor protein in the mice pituitary

Hyperandrogenemia is associated with polycystic ovarian syndrome (PCOS) and imbalances in the pituitary hormones, luteinizing hormone (LH) and follicle-stimulating hormone (FSH) levels. Apelin and its receptor, APJ (class A, rhodopsin-like G- protein-coupled receptor), belongs to adipokines, and its expression has been shown in the pituitary. It is also well known that, hyperandrogenism and PCOS have deregulation of different adipokines. Whether hyperandrogenism also deregulates the apelin system in the pituitary has yet to be investigated. Thus, we have investigated the expression and localization of apelin and its receptor, APJ, in the letrozole-induced hyperandrogenised pituitary of female mice. Our results showed that the apelin, APJ and androgen receptor (AR) expression were upregulated in the anterior pituitary. Furthermore, the immunostaining of LH exhibited increased abundance than FSH. The circulating LH was also found to be elevated compared to FSH levels. The increased LH synthesis and secretion coincides with elevated apelin system in the pituitary of hyperandrogenised mice. Recently, a direct role of apelin has also been reported in the female pituitary, where apelin inhibits LH secretion. Thus, apelin could be one of the factors for deregulated gonadotropin secretion in hyperandrogenised conditions. However, more research is needed to fully understand the complex interactions between apelin and androgen regarding gonadotropin secretion in hyperandrogenised conditions.

Effects of the prenatal and postnatal nurturing environment on the phenotype and gut microbiota of mice with polycystic ovary syndrome induced by prenatal androgen exposure: a cross-fostering study

The gut microbiome is implicated in the pathogenesis of polycystic ovary syndrome (PCOS), and prenatal androgen exposure is involved in the development of PCOS in later life. Our previous study of a mouse model of PCOS induced by prenatal dihydrotestosterone (DHT) exposure showed that the reproductive phenotype of PCOS appears from puberty, followed by the appearance of the metabolic phenotype after young adulthood, while changes in the gut microbiota was already apparent before puberty. To determine whether the prenatal or postnatal nurturing environment primarily contributes to these changes that characterize prenatally androgenized (PNA) offspring, we used a cross-fostering model to evaluate the effects of changes in the postnatal early-life environment of PNA offspring on the development of PCOS-like phenotypes and alterations in the gut microbiota in later life. Female PNA offspring fostered by normal dams (exposed to an abnormal prenatal environment only, fostered PNA) exhibited less marked PCOS-like phenotypes than PNA offspring, especially with respect to the metabolic phenotype. The gut microbiota of the fostered PNA offspring was similar to that of controls before adolescence, but differences between the fostered PNA and control groups became apparent after young adulthood. In conclusion, both prenatal androgen exposure and the postnatal early-life environment created by the DHT injection of mothers contribute to the development of PCOS-like phenotypes and the alterations in the gut microbiota that characterize PNA offspring. Thus, both the pre- and postnatal environments represent targets for the prevention of PCOS and the associated alteration in the gut microbiota in later life.

Metabolic dysregulation and gut dysbiosis linked to hyperandrogenism in female mice

INTRODUCTION

Polycystic ovary syndrome (PCOS) is a common endocrine pathology in women. In addition to infertility, women with PCOS have metabolic dysregulation which predisposes them to Type 2 diabetes, cardiovascular disease and non-alcoholic fatty liver disease. Moreover, women with PCOS have changes in their gut microbial community that may be indicative of dysbiosis. While hyperandrogenism is associated with both the development of metabolic dysfunction and gut dysbiosis in females, the mechanisms involved are not well understood.

METHODS

We used dihydrotestosterone (DHT) and ovariectomy (OVX) mouse models coupled with metabolic assessments and 16S rRNA gene sequencing to explore the contributions of hyperandrogenism and oestrogen deficiency to the development of insulin resistance and gut microbial dysbiosis in pubertal female mice.

RESULTS

We demonstrated that, while DHT treatment or OVX alone were insufficient to induce insulin resistance during the pubertal-to-adult transition, combining OVX with DHT resulted in insulin resistance similar to that observed in letrozole-treated mice with elevated testosterone and decreased oestrogen levels. In addition, our results showed that OVX and DHT in combination resulted in a distinct shift in the gut microbiome compared to DHT or OVX alone, suggesting that the substantial metabolic dysregulation occurring in the OVX + DHT model was accompanied by unique changes in the abundances of gut bacteria including S24-7, Rikenellaceae and Mucispirillum schaedleri.

CONCLUSIONS

While hyperandrogenism plays an important role in the development of metabolic dysregulation in female mice, our results indicate that investigation into additional factors influencing insulin resistance and the gut microbiome during the pubertal-to-adult transition could provide additional insight into the pathophysiology of PCOS.

Current Advances in Cellular Approaches for Pathophysiology and Treatment of Polycystic Ovary Syndrome

Polycystic ovary syndrome (PCOS) is a prevalent gynecological and endocrine disorder that results in irregular menstruation, incomplete follicular development, disrupted ovulation, and reduced fertility rates among affected women of reproductive age. While these symptoms can be managed through appropriate medication and lifestyle interventions, both etiology and treatment options remain limited. Here we provide a comprehensive overview of the latest advancements in cellular approaches utilized for investigating the pathophysiology of PCOS through in vitro cell models, to avoid the confounding systemic effects such as in vitro fertilization (IVF) therapy. The primary objective is to enhance the understanding of abnormalities in PCOS-associated folliculogenesis, particularly focusing on the aberrant roles of granulosa cells and other relevant cell types. Furthermore, this article encompasses analyses of the mechanisms and signaling pathways, microRNA expression and target genes altered in PCOS, and explores the pharmacological approaches considered as potential treatments. By summarizing the aforementioned key findings, this article not only allows us to appreciate the value of using in vitro cell models, but also provides guidance for selecting suitable research models to facilitate the identification of potential treatments and understand the pathophysiology of PCOS at the cellular level.

Mitoguardin2 Is Associated With Hyperandrogenism and Regulates Steroidogenesis in Human Ovarian Granulosa Cells

Polycystic ovary syndrome (PCOS) is an endocrinopathy characterized by hyperandrogenism, anovulation, and polycystic ovaries, in which hyperandrogenism manifests by excess androgen and other steroid hormone abnormalities. Mitochondrial fusion is essential in steroidogenesis, while the role of mitochondrial fusion in granulosa cells of hyperandrogenic PCOS patients remains unclear. In this study, mRNA expression of mitochondrial fusion genes mitoguardin1, -2 (MIGA 1, -2) was significantly increased in granulosa cells of hyperandrogenic PCOS but not PCOS with normal androgen levels, their mRNA expression positively correlated with testosterone levels. Dihydrotestosterone (DHT) treatment in mice led to high expression of MIGA2 in granulosa cells of ovulating follicles. Testosterone or forskolin/ phorbol 12-myristate 13-acetate treatments increased expression of MIGA2 and the steroidogenic acute regulatory protein (StAR) in KGN cells. MIGA2 interacted with StAR and induced StAR localization on mitochondria. Furthermore, MIGA2 overexpression significantly increased cAMP-activated protein kinase A (PKA) and phosphorylation of AMP-activated protein kinase (pAMPK) at T172 but inhibited StAR protein expression. However, MIGA2 overexpression increased CYP11A1, HSD3B2, and CYP19A1 mRNA expression. As a result, MIGA2 overexpression decreased progesterone but increased estradiol synthesis. Besides the androgen receptor, testosterone or DHT might also regulate MIGA2 and pAMPK (T172) through LH/choriogonadotropin receptor-mediated PKA signaling. Taken together, these findings indicate that testosterone regulates MIGA2 via PKA/AMP-activated protein kinase signaling in ovarian granulosa cells. It is suggested mitochondrial fusion in ovarian granulosa cells is associated with hyperandrogenism and potentially leads to abnormal steroidogenesis in PCOS.

Ameliorative effect of sesame oil on experimentally induced polycystic ovary syndrome: A cross-link between XBP-1/PPAR-1, regulatory proteins for lipogenesis/steroids

Polycystic ovary syndrome (PCOS) is a mixed endocrine/metabolic/reproductive disorder in women of reproductive age. Sesame oil (SO) contains sesame lignans & vitamin E with broad-spectrum antioxidant and anti-inflammatory effects. This study investigates the ameliorative effect of SO on experimentally induced PCOS and elucidates the possible molecular mechanisms with a deeper focus on the different signaling pathways involved. The study was carried out on 28 nonpregnant female Wister albino rats that were divided into four equal groups; Group I (control group) received oral 0.5% wt/vol carboxymethyl cellulose daily. Group II (SO group): orally administered SO (2 mL/kg body wt./day) for 21 days. Group III (PCOS group) received letrozole daily, 1 mg/kg, for 21 days. Group IV (PCOS + SO group): concomitantly administered letrozole and SO for 21 days. The serum hormonal and metabolic panel and the homogenate ATF-1, StAR, MAPK, PKA, and PI3K levels of the ovarian tissue were calorimetrically evaluated. However, endoplasmic reticulum (ER) stress was evaluated by ovarian XBP1 and PPAR-γ messenger RNA expression level using the qRT-PCR technique. Ovarian COX-2 was detected immunohistochemically. The results suggest that SO-treated PCOS rats showed a significantly improved hormonal, metabolic panel, inflammatory, and ER stress status with concomitant decreases in ATF-1, StAR, MAPK, PKA, and PI3K in ovarian rats compared to the correspondent values in PCOS without treatment. CONCLUSIONS: The protective effects of SO against PCOS are triggered by ameliorating regulatory proteins of ER stress, lipogenesis, and steroidogenesis through the PI3K/PKA and MAPK/ERK2 signaling cascades. SIGNIFICANCE STATEMENT: Polycystic ovary syndrome (PCOS) is the most common mixed endocrine-metabolic dysfunction among women within the reproductive period, with an estimated prevalence of 5%-26% worldwide. Doctors traditionally recommend metformin for PCOS patients. However, metformin is known to be associated with significant adverse effects and contraindications. This work aimed at shedding light on the ameliorative effect of sesame oil (SO), natural polyunsaturated fatty acids-rich oil, on the induced PCOS model. SO proved to have a marvelous effect on the metabolic and endocrine derangements in the PCOS rat model. We hoped to provide a valuable alternative treatment for PCOS patients to avoid the side effects of metformin and to help PCOS patients for whom metformin is contraindicated.

Efficiency of Chinese medicine Bushen Huatan formula for treatment of polycystic ovary syndrome in mice via regulating gut microbiota and PPARγ pathway

OBJECTIVES

To explore the effect and mechanism of Chinese medicine Bushen Huatan formula in treatment of polycystic ovary syndrome (PCOS).

METHODS

Twenty-four SPF female C57BL/6J mice were randomly divided into 3 groups with 8 animals in each group. Control group was given drinking water ad libitum; PCOS was induced by giving letrozole gavage and high-fat diet in model group and treatment group; treatment group received Bushen Huatan formula suspension for 35 d. The sex hormone levels of mice were detected by enzyme-linked immunosorbent assay. Ovary morphology was observed under light microscope after hematoxylin and eosin staining. The feces in the colon of mice were collected, and the gut microbiota was detected by 16S rRNA sequencing. The short chain fatty acids were detected by gas chromatography-mas spectrometry. The expression of peroxisome proliferator activated receptor (PPARγ) was detected by immunohistochemistry. The mRNA expression of mucin-2, occludin-1, tight junction protein zonula occludens 1 (ZO-1) and PPARγ in intestinal epithelium were detected by realtime RT-PCR. The expression of inducible nitric oxide synthase (iNOS) and PPARγ was detected by Western blotting.

RESULTS

Compared with the control group, the body weight, serum levels of follicle stimulating hormone, luteinizing hormone and testosterone in the model group were increased, and serum levels of estradiol were decreased (all P<0.01); the ovarian structure under light microscope was consistent with the characteristics of PCOS. Compared with the model group, the serum levels of sex hormone and ovarian structure in treatment group were improved. The overall structure of gut microbiota in PCOS model mice changed. Compared with control group, there were significantly reduced abundance of Firmicutes, and increased abundance of Verrucomicrobia, Proteobacteria and Actinobacteria inthe model group at phylum level (all P<0.05); there were significantly reduced abundance of Lactobacillus, and increased abundance of Akkermansia, Lachnoclostridium, Lactococcus and Eubacterium_coprostanoligenes at genus level (all P<0.05). The disordered condition of gut microbiota was significantly improved in treatment group. Compared with control group, the contents of acetic acid, propionic acid and butyric acid in feces of model group were significantly decreased (all P<0.05); while the contents of propionic acid and butyric acid in treatment group were significantly increased compared with model control group (both P<0.05). Compared with control group, the mRNA expression of ZO-1 and protein expression of iNOS in model group were significantly increased, and the protein expression of PPARγ and the mRNA expressions of mucin-2 and occludin-1 were significantly decreased (all P<0.05). Compared with model group, the mRNA expression of ZO-1 and protein expression of iNOS in treatment group were decreased, and the protein expression of PPARγ and the mRNA expressions of mucin-2 and occludin-1 were increased.

CONCLUSIONS

PCOS induced by letrozole high-fat diet induces microflora imbalance in mice. Chinese medicine Bushen Huatan formula may increase the level of short chain fatty acid by regulating gut microbiota, thereby activating the intestinal PPARγ pathway and improving intestinal barrier function to act as a cure for PCOS.

Development and evaluation of novel krill oil-based clomiphene microemulsion as a therapeutic strategy for PCOS treatment

Polycystic ovary syndrome (PCOS) is frequently diagnosed hormonal disorder with reproductive and metabolic complications. The most common symptoms include cyst in ovaries, anovulation, insulin resistance, and obesity. Clomiphene citrate, an ovulating agent, is the first-line drug used to treat PCOS. We hypothesized that clomiphene citrate, by stimulating ovarian function, with krill oil used as an oil phase to improve solubility, by addressing PCOS-associated symptoms might be effective in PCOS. Hence, our goal was to target hormonal imbalance along with PCOS-associated symptoms using a single formulation. The concentration of water (X1), oil (X2), and Smix (surfactant-cosurfactant mixture) (X3) were selected as independent variables, in a simplex lattice design, from microemulsion area derived from a pseuodoternary phase diagram while the globule size (Y1) was selected as a dependent parameter. The optimized microemulsion showed good sphericity having 41 nm globule size, 0.32 poly dispersibility index and + 31 mV zeta potential. The optimized microemulsion was further evaluated in-vivo using letrozole-induced PCOS rats. Formulation treated group reversed the effect of letrozole on body weight and estrus cycle in comparison to the disease control group (p < 0.001). The formulation was also effective in reducing insulin resistance, cholesterol and serum testosterone level (p < 0.001). The in vivo results were supported by histopathological studies where the formulation-treated group showed a marked decrease in the number of cystic follicles and a remarkable increase in the number of growing follicles at variable stages, similar to the normal control group. Thus, the results confirmed that novel krill oil-based clomiphene microemulsion may become a promising therapeutic choice for the treatment of PCOS.

NGF and Its Role in Immunoendocrine Communication during Metabolic Syndrome

Nerve growth factor (NGF) was the first neurotrophin described. This neurotrophin contributes to organogenesis by promoting sensory innervation and angiogenesis in the endocrine and immune systems. Neuronal and non-neuronal cells produce and secrete NGF, and several cell types throughout the body express the high-affinity neurotrophin receptor TrkA and the low-affinity receptor p75NTR. NGF is essential for glucose-stimulated insulin secretion and the complete development of pancreatic islets. Plus, this factor is involved in regulating lipolysis and thermogenesis in adipose tissue. Immune cells produce and respond to NGF, modulating their inflammatory phenotype and the secretion of cytokines, contributing to insulin resistance and metabolic homeostasis. This neurotrophin regulates the synthesis of gonadal steroid hormones, which ultimately participate in the metabolic homeostasis of other tissues. Therefore, we propose that this neurotrophin's imbalance in concentrations and signaling during metabolic syndrome contribute to its pathophysiology. In the present work, we describe the multiple roles of NGF in immunoendocrine organs that are important in metabolic homeostasis and related to the pathophysiology of metabolic syndrome.

The effects of melatonin and metformin on histological characteristics of the ovary and uterus in letrozole-induced polycystic ovarian syndrome mice: A stereological study

Background

Polycystic ovarian syndrome (PCOS) with anovulation, hyperandrogenism, ovarian and uterine histological changes, menstrual irregularities, etc. signs is an infertility type. It seems that melatonin and metformin can improve these abnormalities.

Objective

To evaluate the effects of melatonin and metformin on the ovary and uterus in PCOS-induced mice using stereological methods.

Materials and Methods

Seventy-two adult female BALB/c mice (8-wk-old, 20-30 gr) were randomly divided into control (distilled water, gavage), PCOS (90 µg/kg letrozole, gavage), PCOS+metformin (500 mg/kg, gavage), PCOS+melatonin (10 mg/kg, intraperitoneal injection), and PCOS+melatonin control (0.5% ethanol saline) groups (n = 12/each). Another PCOS group was kept for a month to ensure that PCOS features remained. Finally, a stereological evaluation of the uterus and ovary was carried out, and vaginal cytology and serum testosterone levels were assessed.

Results

PCOS mice treated with metformin and melatonin had lower testosterone levels, body weight, and more regular estrus cycles than the PCOS group (p ≤ 0.001). A significant decrease in conglomerate and daughter gland numbers, and primary, secondary, atretic, and cystic follicles numbers with a significant increase in primordial and Graafian follicles, and corpus luteum numbers (p ≤ 0.001) was seen in these treated mice. Also, endometrial vessels' volume and length significantly increased, but ovarian, endometrial, myometrial, stromal, and glands volume, and endometrial and myometrial thickness dramatically declined (p ≤ 0.001).

Conclusion

It appears that metformin and melatonin could restore the PCOS phenotype including estrus cycle irregularity, high testosterone level, and ovarian and uterine micromorphology to the control levels. However, the 2 treatments had similar effects on the examined parameters.

Dysregulation of intraovarian redox status and steroidogenesis pathway in letrozole-induced PCOS rat model: a possible modulatory role of l-Carnitine

Background

Polycystic ovarian syndrome (PCOS) is a reproductive disorder associated with several endocrine and metabolic alterations. The mechanism underlying this syndrome is controversial. On the other hand, drugs used for the treatment are associated with several side effects and poor in controlling PCOS phenotype. l-Carnitine (LC) has been reported to have a significant regulatory function on the redox and metabolic status of female reproductive system. Nevertheless, its regulatory pathways to regulate PCOS are still under investigation. Therefore, this study aimed to evaluate the effects of LC on the steroidogenic pathways, oxidative stress markers and metabolic profile in letrozole (LTZ)-induced PCOS rat model.

Methods

For this aim, animals were divided into four groups (n = 6). Control group, untreated letrozole-induced PCOS group (1 mg/kg bwt) for 21 days, PCOS group treated with l-Carnitine (100 mg/kg bwt) for 14 days and PCOS group treated with clomiphene citrate (2 mg/kg bwt) for 14 days. Finally, body and ovarian weight, metabolic state(glucose and lipid profile), hormonal assays (testosterone, 17 β estradiol, LH and FSH levels), intraovarian relative gene expression (CYP17A1, StAR, CYP11A1 and CYP19A1 genes), ovarian redox state (malondialdehyde (MDA), reduced glutathione content (GSH) and catalase enzyme activity (CAT)) as well as serum total antioxidant capacity (TAC) were detected. Also, histomorphometric ovarian evaluation (number and diameter of cystic follicles, granulosa cell thickness and theca cell thickness) as well as immune expression of caspase-3 of granulosa cells of cystic follicles were determined.

Results

LC significantly improved ovarian redox state (GSH, MDA and CAT), steroidogenic pathways gene expression (CYP17A1, StAR, CYP11A1 and CYP19A1 genes), hormonal profile (Follicle stimulating hormone (FSH) and luteinizing hormone (LH), testosterone and estradiol), metabolic state (Glucose and lipid profile) histomorphometric alterations and decreased caspase 3 immune reaction of granulosa cells.

Conclusion

l-Carnitine supplementation can ameliorate the PCOS phenotype through its energetic, antioxidant and antiapoptotic functions as well as steroidogenesis regulatory role. This protocol could be modified to produce the best therapeutic benefits, and it could be regarded as a prospective therapeutic intervention for PCOS.

Distinctions in PCOS Induced by Letrozole Vs Dehydroepiandrosterone With High-fat Diet in Mouse Model

Polycystic ovarian syndrome (PCOS) is a complex health condition associated with metabolic disturbances and infertility. Recent data suggest that the prevalence of PCOS is increasing among women globally, although the etiology of these trends is undefined. Consequently, preclinical models that better reflect the biology of PCOS are urgently needed to facilitate research that can lead to the discovery of prevention strategies or improved management. The existing animal models have several limitations as they do not reflect all the PCOS features metabolically and/or phenotypically. Therefore, there is no clear consensus on the use of appropriate animal model and selection of the most appropriate PCOS-inducing agent. To that end, we have established a Swiss albino mouse model of PCOS based on 3 weeks of daily treatment with letrozole (50 μg/day; intraperitoneal) and dehydroepiandrosterone (DHEA, 6 mg/100 g body weight; subcutaneous) in 5-week-old female mice fed on normal or high-fat diet (HFD). Mice were regularly assessed for body weight, blood glucose, and estrous cycle. Three weeks after drug administration, mice were sacrificed and assessed for blood-based metabolic parameters as well as ovarian function. Our results indicate that DHEA combined with HFD produces changes mimicking those of clinical PCOS, including elevated serum testosterone and luteinizing hormone, dyslipidemia, poor ovarian microenvironment, and development of multiple ovarian cysts, recapitulating cardinal features of PCOS. In comparison, normal diet and/or letrozole produced fewer features of PCOS. The data from the experimental models presented here can improve our understanding of PCOS, a growing concern in women's health.

The Role of a High-Fat, High-Fructose Diet on Letrozole-Induced Polycystic Ovarian Syndrome in Prepubertal Mice

This study aims to investigate the effects of a high-fat, high-fructose (HF/HFr) diet on metabolic/endocrine dysregulations associated with letrozole (LET)-induced Polycystic Ovarian Syndrome (PCOS) in prepubertal female mice. Thirty-two prepubertal C57BL/6 mice were randomly divided into four groups of eight and implanted with LET or a placebo, with simultaneous administration of an HF/HFr/standard diet for five weeks. After sacrifice, the liver and blood were collected for selected biochemical analyses. The ovaries were taken for histopathological examination. The LET+HF/HFr group gained significantly more weight than the LET-treated mice. Both the LET+HF/HFr and the placebo-treated mice on the HF/HFr diet developed polycystic ovaries. Moreover the LET+HF/HFr group had significantly elevated testosterone levels, worsened lipid profile and indices of insulin sensitivity. In turn, the HF/HFr diet alone led to similar changes in the LET-treated group, except for the indices of insulin sensitivity. Hepatic steatosis also occurred in both HF/HFr groups. The LET-treated group did not develop endocrine or metabolic abnormalities, but polycystic ovaries were seen. Since the HF/HFr diet can cause substantial metabolic and reproductive dysregulation in both LET-treated and placebo mice, food items rich in simple sugar-particularly fructose-and saturated fat, which have the potential to lead to PCOS progression, should be eliminated from the diet of young females.

Maternal aromatase inhibition via letrozole altered RFamide-related peptide-3 and gonadotropin-releasing hormone expression in pubertal female rats

Objectives

Despite prevalence of polycystic ovary syndrome (PCOS) among childbearing women and development of many animal models for this syndrome, information on its etiology is still scarce. The intrauterine hyperandrogenic environment may underlie changes at the level of hypothalamus, pituitary, ovary organization in female offspring, and PCOS later in life. Letrozole has been shown to mimic reproductive and metabolic characteristics of PCOS in adult rodent models. Therefore, this research aimed to assess the condition in a prenatal letrozole-treated rat model.

Materials and Methods

Twenty-eight female rats dams receiving letrozole at certain doses during late pregnancy were used in the trial. Pregnant Sprague-Dawley rats (n=21) received letrozole treatment on gestation days 16-18 at doses of 1.25, 1.0, 0.75, 0.5, and 0.25 mg/kg body weight (BW).

Results

Prenatal letrozole treatment delayed parturition time and reduced the litter size in pregnant dams (P<0.0001). Late puberty onset, irregular ovarian cyclicity, increased anogenital distance (AGD), body weight gain, serum testosterone concentration, and reduced estradiol levels (P<0.0001) were observed in the female offspring of dams receiving 1.25 and 1 mg/kg BW letrozole. Furthermore, letrozole at 1.25 and 1 mg/kg BW showed increased RFRP and decreased GnRH mRNA expression (P<0.0001). Letrozole treatment at doses of 1 mg/kg BW and lower was not fetotoxic.

Conclusion

It was concluded that 1 mg/kg BW letrozole may be suggested for prenatal PCOS induction.

Temporal relationship between alterations in the gut microbiome and the development of polycystic ovary syndrome-like phenotypes in prenatally androgenized female mice

It has been recently recognized that prenatal androgen exposure is involved in the development of polycystic ovary syndrome (PCOS) in adulthood. In addition, the gut microbiome in adult patients and rodents with PCOS differs from that of healthy individuals. Moreover, recent studies have suggested that the gut microbiome may play a causative role in the pathogenesis of PCOS. We wondered whether prenatal androgen exposure induces gut microbial dysbiosis early in life and is associated with the development of PCOS in later life. To test this hypothesis, we studied the development of PCOS-like phenotypes in prenatally androgenized (PNA) female mice and compared the gut microbiome of PNA and control offspring from 4 to 16 weeks of age. PNA offspring showed a reproductive phenotype from 6 weeks and a metabolic phenotype from 12 weeks of age. The α-diversity of the gut microbiome of the PNA group was higher at 8 weeks and lower at 12 and 16 weeks of age, and the β-diversity differed from control at 8 weeks. However, a significant difference in the composition of gut microbiome between the PNA and control groups was already apparent at 4 weeks. Allobaculum and Roseburia were less abundant in PNA offspring, and may therefore be targets for future interventional studies. In conclusion, abnormalities in the gut microbiome appear as early as or even before PCOS-like phenotypes develop in PNA mice. Thus, the gut microbiome in early life is a potential target for the prevention of PCOS in later life.

Intestinal Flora is a Key Factor in Insulin Resistance and Contributes to the Development of Polycystic Ovary Syndrome

CONTEXT

The key gut microbial biomarkers for polycystic ovarian syndrome (PCOS) and how dysbiosis causes insulin resistance and PCOS remain unclear.

OBJECTIVE

To assess the characteristics of intestinal flora in PCOS and explore whether abnormal intestinal flora can affect insulin resistance and promote PCOS and whether chenodeoxycholic acid (CDCA) can activate intestinal farnesoid X receptor (FXR), improving glucose metabolism in PCOS.

SETTING AND DESIGN

The intestinal flora of treatment-naïve PCOS patients and hormonally healthy controls was analyzed. Phenotype analysis, intestinal flora analysis, and global metabolomic profiling of caecal contents were performed on a letrozole-induced PCOS mouse model; similar analyses were conducted after 35 days of antibiotic treatment on the PCOS mouse model, and glucose tolerance testing was performed on the PCOS mouse model after a 35-day CDCA treatment. Mice receiving fecal microbiota transplants from PCOS patients or healthy controls were evaluated after 10 weeks.

RESULTS

Bacteroides was significantly enriched in treatment-naïve PCOS patients. The enrichment in Bacteroides was reproduced in the PCOS mouse model. Gut microbiota removal ameliorated the PCOS phenotype and insulin resistance and increased relative FXR mRNA levels in the ileum and serum fibroblast growth factor 15 levels. PCOS stool-transplanted mice exhibited insulin resistance at 10 weeks but not PCOS. Treating the PCOS mouse model with CDCA improved glucose metabolism.

CONCLUSIONS

Bacteroides is a key microbial biomarker in PCOS and shows diagnostic value. Gut dysbiosis can cause insulin resistance. FXR activation might play a beneficial rather than detrimental role in glucose metabolism in PCOS.

Mesenchymal stem cell therapy ameliorates metabolic dysfunction and restores fertility in a PCOS mouse model through interleukin-10

BACKGROUND

Polycystic ovary syndrome (PCOS) is the most common endocrine and metabolic disorder in reproductive-age women. Excessive inflammation and elevated androgen production from ovarian theca cells are key features of PCOS. Human bone marrow mesenchymal stem cells (BM-hMSC) and their secreted factors (secretome) exhibit robust anti-inflammatory capabilities in various biological systems. We evaluated the therapeutic efficacy of BM-hMSC and its secretome in both in vitro and in vivo PCOS models.

METHODS

For in vitro experiment, we treated conditioned media from BM-hMSC to androgen-producing H293R cells and analyzed androgen-producing gene expression. For in vivo experiment, BM-hMSC were implanted into letrozole (LTZ)-induced PCOS mouse model. BM-hMSC effect in androgen-producing cells or PCOS model mice was assessed by monitoring cell proliferation (immunohistochemistry), steroidogenic gene expression (quantitative real-time polymerase chain reaction [qRT-PCR] and Western blot, animal tissue assay (H&E staining), and fertility by pup delivery.

RESULTS

BM-hMSC significantly downregulate steroidogenic gene expression, curb inflammation, and restore fertility in treated PCOS animals. The anti-inflammatory cytokine interleukin-10 (IL-10) played a key role in mediating the effects of BM-hMSC in our PCOS models. We demonstrated that BM-hMSC treatment was improved in metabolic and reproductive markers in our PCOS model and able to restore fertility.

CONCLUSION

Our study demonstrates for the first time the efficacy of intra-ovarian injection of BM-hMSC or its secretome to treat PCOS-related phenotypes, including both metabolic and reproductive dysfunction. This approach may represent a novel therapeutic option for women with PCOS. Our results suggest that BM-hMSC can reverse PCOS-induced inflammation through IL-10 secretion. BM-hMSC might be a novel and robust therapeutic approach for PCOS treatment.

Modulation of steroidogenesis by Actaea racemosa and vitamin C combination, in letrozole induced polycystic ovarian syndrome rat model: promising activity without the risk of hepatic adverse effect

Background

Complementary remedies such as the Chinese herb ‘Sheng Ma’ (Black cohosh; Actaea racemosa ‘AR’) are being sought to overcome the shortcomings of conventional hormonal and surgical therapies developed for the treatment of polycystic ovary syndrome (PCOS). However, AR-induced hepatotoxicity necessitates a cautionary warning to be labeled on its products as recommended by the United States Pharmacopeia, where four out of seven hepatotoxic cases in Sweden were possibly associated with black cohosh products.

Methods

We investigated the effects, safety, and molecular targets of black cohosh ethanolic extract and/or vitamin C on ovarian functionality and oxidative response in hyperandrogenism-induced PCOS rats. A well-established rat model using oral letrozole, daily, for 21 days was employed. The rats then received the AR extract with and without vitamin C for 28 days. The hormonal evaluation, antioxidant status, histopathological examination, immunohistochemical analysis, cell proliferation, and the expression ratio of the aromatase (Cyp19α1) gene were evaluated. Additionally, holistic profiling of the AR arsenal of secondary metabolites was performed using ultra-high-performance liquid chromatography (UHPLC) coupled with quadrupole high-resolution time of flight mass spectrometry (QTOF-MS).

Results

Beneficial effects were exerted by AR in PCOS rats as antioxidant status, hormonal profile, lipid profile, glucose level, liver functions, and the induced Ki-67 expression in the granulosa, theca cell layers and interstitial stromal cells were all improved. Notably, the combination of AR with vitamin C was not only more effective in reversing the dysregulated levels of testosterone, luteinizing hormone, and mRNA level of Cyp19α1 gene in the PCOS rat, but also safer. The combination regulated both ovarian and hepatic malondialdehyde (MDA) and glutathione (GSH) levels with histological improvement observed in the liver and ovaries. In addition, the untargeted metabolomic profiling enabled the identification of 61 metabolites allocated in five major chemical classes.

Conclusion

This study demonstrated the benefit of the combinatorial effects of AR and vitamin C in mitigating the reproductive and metabolic disorders associated with PCOS with the elimination of AR hepatotoxic risk.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13020-021-00444-z.

Intersection of Polycystic Ovary Syndrome and the Gut Microbiome

The etiology of polycystic ovary syndrome (PCOS) remains unclear, although studies indicate that both genetic and environmental factors contribute to the syndrome. In 2012, Tremellen and Pearce proposed the idea that dysbiosis of the intestinal (gut) microbiome is a causative factor of metabolic and reproductive manifestations of PCOS. In the past 5 years, studies in both humans and rodent models have demonstrated that changes in the taxonomic composition of gut bacteria are associated with PCOS. Studies have also clearly shown that these changes in gut microbiota are associated with PCOS as opposed to obesity, since these changes are observed in women with PCOS that are both of a normal weight or obese, as well as in adolescent girls with PCOS and obesity compared with body mass index- and age-matched females without the disorder. Additionally, studies in both women with PCOS and rodent models of PCOS demonstrated that hyperandrogenism is associated with gut microbial dysbiosis, indicating that androgens may modulate the gut microbial community in females. One study reported that the fecal microbiome transplantation of stool from women with PCOS or exposure to certain bacteria resulted in a PCOS-like phenotype in mice, while other studies showed that exposure to a healthy gut microbiome, pre/probiotics, or specific gut metabolites resulted in protection from developing PCOS-like traits in mice. Altogether, these results suggest that dysbiosis of the gut microbiome may be sufficient to develop PCOS-like symptoms and that modulation of the gut microbiome may be a potential therapeutic target for PCOS.

Potential effect of adrenomedullin on metabolic and endocrinal dysfunctions in the experimentally induced polycystic ovary: Targeting implication of endoplasmic reticulum stress

This study investigated the potential effect of adrenomedullin (ADM) on metabolic and endocrinal dysfunctions in experimentally induced polycystic ovary. Twenty-four female Wistar rats were allocated into three groups: control; polycystic ovary syndrome (PCOS) in which PCOS was induced by letrozole, orally in a dose of 1 mg/kg once daily for 3 weeks; and ADM group in which ADM was injected intraperitonally in a dose of 3.5/μg/twice daily for 4 weeks. At the end of the experimental period, the serum sex hormone profile, ADM, fasting glucose, insulin, homeostatic model assessment of insulin resistance, and lipid parameters were determined. Ovarian tissue homogenates were used to determine malondialdehyde, total antioxidant capacity, glutathione peroxidase activity, tumor necrosis factor α, interleukin 6, B cell lymphoma-2 (Bcl-2), and Bcl-2 associated X protein. The profibrotic growth factors, including transforming growth factor β1 and connective tissue growth factor, were determined; and also, the relative gene expression of endoplasmic reticulum (ER) stress, including (Xbox-binding protein-1 [XBP-1], activating transcription factor 6 [ATF6], and homologous protein [CHOP]), serine/threonine kinase 1 (Akt1), phosphatidylinositol 3-kinase (PI3K), and peroxisome proliferator-activated receptor γ (PPAR-γ) were determined. Finally, histopathological analysis of the ovaries was evaluated. PCOS group exhibited increased ER stress, suppressing of PI3K/Akt1 and PPAR-γ pathways, imbalance of sex hormonal profile, hyperglycemia, insulin resistance, dyslipidemia, increased profibrotic factors, and abnormal ovarian histopathological picture, while ADM treatment alleviated these disturbances occurring in the PCOS model. We concluded that ADM mitigated PCOS via attenuating the ER stress, in addition to activation of PI3K/Akt1 and PPAR-γ pathways, its antioxidant, anti-inflammatory, antiapoptotic, and antifibrotic properties.

Involvement of endogenous testosterone in hepatic steatosis in women with polycystic ovarian syndrome

AIMS

The prevalence of nonalcoholic fatty liver disease (NAFLD) is higher in women with polycystic ovarian syndrome (PCOS) than that in healthy women. This association can be explained in part by the resistance to insulin and the prevalence of obesity, which are fueled by high androgen levels. However, there is little evidence of the involvement of endogenous testosterone in hepatic steatosis in women with PCOS. Here, we treated Sprague Dawley rats with the aromatase inhibitor, letrozole, to increase the endogenous testosterone level and to decrease the estradiol levels. We also quantified the testosterone levels in human serum specimens and HepG2 cells to investigate the effects of androgens on hepatic steatosis and liver dysfunction.

RESULTS

Twenty-nine PCOS patients and twenty healthy women were enrolled. Alanine transaminase and aspartate transaminase (AST) levels were increased in women with PCOS, and a strong correlation between testosterone and AST levels was observed. After letrozole treatment for 90 days, rats were significantly more obese, with animals developing hepatic steatosis and moderate insulin resistance. Additional experiments revealed that excess androgen inhibited the AMP-activated protein kinase alpha pathway in letrozole-treated livers and dihydrotestosterone (DHT)-treated HepG2 cells, thereby causing steatosis.

INNOVATION AND CONCLUSION

Our results show that an elevated endogenous testosterone level can induce hepatic steatosis. Decreasing the endogenous testosterone level in hepatocytes may represent a new approach in the treatment of NAFLD in PCOS patients.

Increased Skeletal Muscle Fiber Cross-Sectional Area, Muscle Phenotype Shift, and Altered Insulin Signaling in Rat Hindlimb Muscles in a Prenatally Androgenized Rat Model for Polycystic Ovary Syndrome

Women with polycystic ovary syndrome (PCOS) are reported to have greater lean mass and insulin resistance. To examine muscular changes in a prenatally androgenized (PNA) rat model for PCOS, Sprague-Dawley rats were exposed to 5 mg testosterone or vehicle daily on gestational days 16-19. At 15 weeks of age, endurance on a rota-rod treadmill was measured. At 16 weeks of age, fasting blood glucose and insulin, hindlimb skeletal muscle mass, muscle fiber cross-sectional area (CSA) and composition, and intra- and peri-muscular lipid droplets were examined. Expression of mitochondrial marker ATP synthase and insulin signaling proteins were also investigated. Compared with controls, PNA female rats demonstrated greater total body and hindlimb muscle weights, greater muscle fiber CSA, and trending reduced time on the rota-rod. An increase in fibers co-expressing the slow and fast isoforms of myosin (90 vs. 86%, p < 0.05) and greater expression of ATP synthase (6-fold, p < 0.005) were observed in the gastrocnemius (GN) muscle. More lipid content was observed in GN and tibialis anterior (TA) muscles. PNA rats had elevated fasting serum insulin (1.9 vs. 1.2 ng/mL, p < 0.005) but comparable fasting glucose. Expression of total and Ser^636/9-phosphorylated IRS1 were altered in PNA rat hindlimb muscles. Together, skeletal muscle alterations in hindlimb muscles of a PNA rat model for PCOS may represent consequences of, or adaptations to, insulin resistance in this model.

Animal Models to Understand the Etiology and Pathophysiology of Polycystic Ovary Syndrome

More than 1 out of 10 women worldwide are diagnosed with polycystic ovary syndrome (PCOS), the leading cause of female reproductive and metabolic dysfunction. Despite its high prevalence, PCOS and its accompanying morbidities are likely underdiagnosed, averaging > 2 years and 3 physicians before women are diagnosed. Although it has been intensively researched, the underlying cause(s) of PCOS have yet to be defined. In order to understand PCOS pathophysiology, its developmental origins, and how to predict and prevent PCOS onset, there is an urgent need for safe and effective markers and treatments. In this review, we detail which animal models are more suitable for contributing to our understanding of the etiology and pathophysiology of PCOS. We summarize and highlight advantages and limitations of hormonal or genetic manipulation of animal models, as well as of naturally occurring PCOS-like females.

Hyperactive LH Pulses and Elevated Kisspeptin and NKB Gene Expression in the Arcuate Nucleus of a PCOS Mouse Model

Polycystic ovary syndrome (PCOS), a common reproductive disorder in women, is characterized by hyperandrogenemia, chronic anovulation, cystic ovarian follicles, and luteinizing hormone (LH) hyper-pulsatility, but the pathophysiology isn't completely understood. We recently reported a novel mouse model of PCOS using chronic letrozole (LET; aromatase inhibitor). Letrozole-treated females demonstrate multiple PCOS-like phenotypes, including polycystic ovaries, anovulation, and elevated circulating testosterone and LH, assayed in "one-off" measures. However, due to technical limitations, in vivo LH pulsatile secretion, which is elevated in PCOS women, was not previously studied, nor were the possible changes in reproductive neurons. Here, we used recent technical advances to examine in vivo LH pulse dynamics of freely moving LET female mice versus control and ovariectomized (OVX) mice. We also determined whether neural gene expression of important reproductive regulators such as kisspeptin, neurokinin B (NKB), and dynorphin, is altered in LET females. Compared to controls, LET females exhibited very rapid, elevated in vivo LH pulsatility, with increased pulse frequency, amplitude, and basal levels, similar to PCOS women. Letrozole-treated mice also had markedly elevated Kiss1, Tac2, and Pdyn expression and increased Kiss1 neuronal activation in the hypothalamic arcuate nucleus. Notably, the hyperactive LH pulses and increased kisspeptin neuron measures of LET mice were not as elevated as OVX females. Our findings indicate that LET mice, like PCOS women, have markedly elevated LH pulsatility, which likely drives increased androgen secretion. Increased hypothalamic kisspeptin and NKB levels may be fundamental contributors to the hyperactive LH pulse secretion in the LET PCOS-like condition and, perhaps, in PCOS women.

Spironolactone reversed hepato-ovarian triglyceride accumulation caused by letrozole-induced polycystic ovarian syndrome: tissue uric acid-a familiar foe

Polycystic ovarian syndrome (PCOS) is a complex endocrine disease among women of reproductive age and is one of the main causes of infertility. Non-alcoholic fatty liver disease (NAFLD), the most prominent chronic liver disease in adults, is characterized by excess hepatic triglyceride (TG) accumulation. PCOS women have increased risk of NAFLD and uric acid has been documented to have a positive correlation with subclinical tissue damage and might be the link in the cystic. Spironolactone (SPL) is a mineralocorticoid receptor (MR) blocker that has been in wide clinical use for some decades. In this research, we investigated the effects of SPL on ovarian and hepatic tissue damage in experimental PCOS rats induced by letrozole (LET). A total of eighteen adult female Wistar rats were used for this study and the animals divided into 3 groups are treated with vehicle, LET (1 mg/kg), and LET+SPL (SPL; 0.25 mg/kg), p.o. once daily respectively for 21 uninterrupted days. Results showed that LET treatment induced features of PCOS characterized by increased plasma testosterone (T) and luteinizing hormone (LH) together with increased body weight. Abnormal ovarian and hepatic histomorphological changes were also observed with elevated uric acid (UA) and TG accumulation in both tissues respectively. Treatment with SPL however attenuated the elevated testosterone in the LET-induced PCOS model accompanied with a reversal in the observed ovarian and hepatic UA, TG accumulation, and altered histomorphological changes. Taken together, spironolactone reversed the PCOS-induced ovarian and hepatic tissue damage by suppressing tissue UA and TG accumulation.

Letrozole treatment of pubertal female mice results in activational effects on reproduction, metabolism and the gut microbiome

Polycystic ovary syndrome (PCOS) is a common endocrine disorder in reproductive-aged women that is comprised of two out of the following three features: hyperandrogenism, oligo- or amenorrhea, or polycystic ovaries. In addition to infertility, many women with PCOS have metabolic dysregulation that increases the risk of developing type 2 diabetes, hypertension, and non-alcoholic fatty liver disease. Changes in the gut microbiome are associated with PCOS and gut microbes may be involved in the pathology of this disorder. Since PCOS often manifests in the early reproductive years, puberty is considered to be a critical time period for the development of PCOS. Exposure to sex steroid hormones during development results in permanent, organizational effects, while activational effects are transient and require the continued presence of the hormone. Androgens exert organizational effects during prenatal or early post-natal development, but it is unclear whether androgen excess results in organizational or activational effects during puberty. We recently developed a letrozole-induced PCOS mouse model that recapitulates both reproductive and metabolic phenotypes of PCOS. In this study, we investigated whether letrozole treatment of pubertal female mice exerts organizational or activational effects on host physiology and the gut microbiome. Two months after letrozole removal, we observed recovery of reproductive and metabolic parameters, as well as diversity and composition of the gut microbiome, indicating that letrozole treatment of female mice during puberty resulted in predominantly activational effects. These results suggest that if exposure to excess androgens during puberty leads to the development of PCOS, reduction of androgen levels during this time may improve reproductive and metabolic phenotypes in women with PCOS. These results also imply that continuous letrozole exposure is required to model PCOS in pubertal female mice since letrozole exerts activational rather than organizational effects during puberty.

Exposure to a Healthy Gut Microbiome Protects Against Reproductive and Metabolic Dysregulation in a PCOS Mouse Model

Polycystic ovary syndrome (PCOS) is a common endocrine disorder affecting ∼10% to 15% of reproductive-aged women worldwide. Diagnosis requires two of the following: hyperandrogenism, oligo-ovulation or anovulation, and polycystic ovaries. In addition to reproductive dysfunction, many women with PCOS display metabolic abnormalities associated with hyperandrogenism. Recent studies have reported that the gut microbiome is altered in women with PCOS and rodent models of the disorder. However, it is unknown whether the gut microbiome plays a causal role in the development and pathology of PCOS. Given its potential role, we hypothesized that exposure to a healthy gut microbiome would protect against development of PCOS. A cohousing study was performed using a letrozole-induced PCOS mouse model that recapitulates many reproductive and metabolic characteristics of PCOS. Because mice are coprophagic, cohousing results in repeated, noninvasive inoculation of gut microbes in cohoused mice via the fecal-oral route. In contrast to letrozole-treated mice housed together, letrozole mice cohoused with placebo mice showed significant improvement in both reproductive and metabolic PCOS phenotypes. Using 16S rRNA gene sequencing, we also observed that the overall composition of the gut microbiome and the relative abundance of Coprobacillus and Lactobacillus differed in letrozole-treated mice cohoused with placebo mice compared with letrozole mice housed together. These results suggest that dysbiosis of the gut microbiome may play a causal role in PCOS and that modulation of the gut microbiome may be a potential treatment option for PCOS.

Letrozole treatment of adult female mice results in a similar reproductive phenotype but distinct changes in metabolism and the gut microbiome compared to pubertal mice

BACKGROUND

A majority of women with polycystic ovary syndrome (PCOS) have metabolic dysfunction that results in an increased risk of type 2 diabetes. We previously developed a pubertal mouse model using the aromatase inhibitor, letrozole, which recapitulates many of the reproductive and metabolic features of PCOS. To further our understanding of the effects of androgen excess, we compared the effects of letrozole treatment initiated in puberty versus adulthood on reproductive and metabolic phenotypes as well as on the gut microbiome.

RESULTS

Letrozole treatment of both pubertal and adult female mice resulted in reproductive hallmarks of PCOS, including hyperandrogenemia, anovulation and polycystic ovaries. However, unlike pubertal mice, treatment of adult female mice resulted in modest weight gain and abdominal adiposity, minimal elevation in fasting blood glucose and insulin levels, and no detectable insulin resistance. In addition, letrozole treatment of adult mice was associated with a distinct shift in gut microbial diversity compared to letrozole treatment of pubertal mice.

CONCLUSIONS

Our results indicate that dysregulation of metabolism and the gut microbiome in PCOS may be influenced by the timing of androgen exposure. In addition, the minimal weight gain and lack of insulin resistance in adult female mice after letrozole treatment indicates that this model may be useful for investigating the effects of hyperandrogenemia on the hypothalamic-pituitary-gonadal axis and the periphery without the influence of substantial metabolic dysregulation.

Sex, Microbes, and Polycystic Ovary Syndrome

Recent studies have shown that sex and sex steroids influence the composition of the gut microbiome. These studies also indicate that steroid regulation of the gut microbiome may play a role in pathological situations of hormonal excess, such as PCOS. Indeed, studies demonstrated that PCOS is associated with decreased alpha diversity and changes in specific Bacteroidetes and Firmicutes, previously associated with metabolic dysregulation. These studies suggest that androgens may regulate the gut microbiome in females and that hyperandrogenism may be linked with a gut 'dysbiosis' in PCOS. Future mechanistic studies will be required to elucidate how sex steroids regulate the composition and function of the gut microbial community and what the consequences of this regulation are for the host.

Metabolic Effects of Testosterone Hormone Therapy in Normal and Orchiectomized Male Rats: From Indirect Calorimetry to Lipolytic Enzymes

BACKGROUND AND AIM

Changes in total energy expenditure (TEE) and substrate metabolism may help explain the metabolic actions of testosterone (T). This study measured respiratory quotient (RQ), TEE, ghrelin, insulin, and key lipolysis enzyme concentrations in relation to body weight (wt) and food intake (FI) in both normal and bilaterally orchiectomized rats with/without T treatment.

METHODS

In total, thirty-two male Wistar rats (300-400 g) were divided into four groups (n = 8/group), including (a) sham-operated and vehicle-injected group (Sham), (b) T-treated sham group (T-Sham) for which sham-operated rats were injected with IM testosterone undecanoate (100 mg/kg, for one week), (c) orchiectomy and vehicle-injected group (Orch), and (d) T-replaced orchiectomy group (T-Orch). After one week, FI and wt were automatically recorded, indirect calorimetry parameters were measured, and blood samples were collected to measure T, ghrelin, insulin, growth hormone (GH), glucose, hormone-sensitive lipase (HSL), adipocyte triglyceride lipase (ATGL), free fatty acids (FFA), and lipid profiles.

RESULTS

Orchiectomy decreased ghrelin, GH, and insulin levels, increased TEE and RQ, and lowered FI and wt. The T-Orch group exhibited increased levels of ghrelin (3-fold), insulin, GH, blood levels of lipolysis products, TEE, and FI in addition to reduced glucose levels (P < 0.05). This group demonstrated no significant changes in wt. In the T-Sham group, T increased ghrelin and insulin levels (P < 0.05) with strong positive correlations (r = 0.663 and 0.644, respectively, P < 0.05), increased ATGL levels, RQ toward carbohydrate utilization ranges, and TEE, and reduced HSL levels (P < 0.05) with insignificant changes in FI or wt.

CONCLUSIONS

T administration in orchiectomized rats significantly increased orexigenic mediators such as ghrelin and insulin without inducing any significant changes in wt. The mechanism for this finding might be the increased TEE and the stimulation of lipolysis through the ATGL enzyme. The associated rise of GH might help in interference with accumulation of lipid in adipose tissue. Apart from the effect on GH, T-Sham showed similar effects of T supplementation.

LncRNAs and miRs as epigenetic signatures in diabetic cardiac fibrosis: new advances and perspectives

PURPOSE

Diabetic cardiomyopathy (DCM) is a serious cardiac complication of diabetes, which further lead to heartfailure. It is known that diabetes-induced cardiac fibrosis is a key pathogenic factor contributing topathological changes in DCM. However, pathogenetic mechanisms underlying diabetes cardiac fibrosis arestill elusive. Recent studies have indicated that noncoding RNAs (ncRNAs) play a key role in diabetescardiac fibrosis. The increasing complexity of epigenetic regulator poses great challenges to ourconventional conceptions regarding how ncRNAs regulate diabetes cardiac fibrosis.

METHODS

We searched PubMed, Web of Science, and Scopus for manuscripts published prior to April 2018 using keywords "Diabetic cardiomyopathy" AND " diabetes cardiac fibrosis " OR " noncoding RNAs " OR " longnoncoding RNAs " OR " microRNAs " OR "epigenetic". Manuscripts were collated, studied and carriedforward for discussion where appropriate.

RESULTS

Based on the view that during diabetic cardiac fibrosis, ncRNAs are able to regulate diabetic cardiac fibrosisby targeting genes involved in epigenetic pathways. Many studies have focused on ncRNAs, an epigeneticregulator deregulating protein-coding genes in diabetic cardiac fibrosis, to identify potential therapeutictargets. Recent advances and new perspectives have found that long noncoding RNAs and microRNAs,exert their own effects on the progression of diabetic cardiac fibrosis.

CONCLUSION

We firstly examine the growing role of ncRNAs characteristics and ncRNAs-regulated genes involved indiabetic cardiac fibrosis. Then, we provide several possible therapeutic strategies and highlight the potentialof molecular mechanisms in which targeting epigenetic regulators are considered as an effective means of treating diabetic cardiac fibrosis.

Comparison of Androgen Levels, Endocrine and Metabolic Indices, and Clinical Findings in Women with Polycystic Ovary Syndrome in Uygur and Han Ethnic Groups from Xinjiang Province in China

BACKGROUND The aim of this study was to compare androgen levels, endocrine and metabolic indices, and clinical findings in women with polycystic ovary syndrome (PCOS) in Uygur and Han ethnic groups from Xinjiang Province, China. MATERIAL AND METHODS Between January 2016 to May 2017 clinical data were collected from Uygur (N=82) and Han (N=100) women diagnosed with PCOS, including age, body mass index (BMI), the Ferriman-Gallwey (mFG) hirsutism score, and waist-to-hip ratio (WHR). Blood samples obtained from all study participants were used to measure androgenic steroid levels, including androgen, androstenedione, dehydroepiandrosterone (DHEA), dihydrotestosterone (DHT), and the free androgen index (FAI). Endocrine indices measured included sex-hormone binding globulin (SHBG), luteinizing hormone (LH), follicle-stimulating hormone (FSH), estradiol (E2), and prolactin (PL). Metabolic indices measured included insulin, glucose, total cholesterol (TC), triglyceride (TG), high-density lipoprotein (HDL), triglyceride (TG), and low-density lipoprotein (LDL). RESULTS The FAI in Uygur women with PCOS (4.89) was significantly increased compared with Han women with PCOS (2.78) (p<0.05); androgen levels were significantly correlated with the FAI, glucose, insulin, TC, HDL, and LDL (p<0.05); androstenedione levels were positively correlated with glucose and insulin levels (p<0.05). In Han women with PCOS, androgen levels were negatively correlated with TG levels and positively correlated with TC levels (p<0.05); the FAI was positively correlated with glucose and insulin levels (p<0.05). CONCLUSIONS There were significant differences in androgen levels, endocrine, and metabolic indices in women with PCOS between the Uygur and Han ethnic groups from Xinjiang Province in China.

Antiandrogen Treatment Ameliorates Reproductive and Metabolic Phenotypes in the Letrozole-Induced Mouse Model of PCOS

Polycystic ovary syndrome (PCOS), the most common endocrinopathy in women of reproductive age, is characterized by hyperandrogenism, anovulation, and polycystic ovaries. Although its etiology is unknown, excess androgens are thought to be a critical factor driving the pathology of PCOS. We previously demonstrated that continuous exposure to the aromatase inhibitor letrozole (LET) in mice produces many hallmarks of PCOS, including elevated testosterone (T) and luteinizing hormone, anovulation, and obesity. In the current study, we sought to determine whether androgen receptor (AR) actions are responsible for any of the phenotypes observed in LET mice. C57BL/6 female mice were subcutaneously implanted with LET or placebo control and subsequently treated with the nonsteroidal AR antagonist flutamide or vehicle control. Flutamide treatment in LET females reversed elevated T levels and restored ovarian expression of Cyp17a1 (critical for androgen synthesis) to normal levels. Pituitary expression of Lhb was decreased in LET females that received flutamide treatment, with no changes in expression of Fshb or Gnrhr. Flutamide treatment also restored estrous cycling and reduced the number of ovarian cyst-like follicles in LET females. Furthermore, body weight and adipocyte size were decreased in flutamide-treated LET females. Altogether, our findings provide strong evidence that AR signaling is responsible for many key reproductive and metabolic PCOS phenotypes and further establish the LET mouse model as an important tool for the study of androgen excess.