Rescue of obesity-induced infertility in female mice due to a pituitary-specific knockout of the insulin receptor

Polycystic ovary syndrome as a metabolic disease

Polycystic ovary syndrome (PCOS) is a heterogeneous familial disorder affecting up to one in five women. The aetiology remains unclear, but available evidence suggests it is a polygenic disorder with epigenetic, developmental, and environmental components. The diagnostic criteria for PCOS are based on reproductive features, and the syndrome is categorized into several phenotypes that can vary by race and ethnicity. Insulin resistance and metabolic dysfunction have a crucial role in the pathogenesis of the syndrome and contribute to many adverse metabolic outcomes that place a substantial burden on the health of women with PCOS across their lifespan. Metabolic abnormalities like those identified in women with PCOS are also present in their female and male first-degree relatives. Overall, more emphasis is required on defining PCOS as a metabolic disorder in addition to a reproductive one. This approach could affect the management and future treatment options for the syndrome. The rationale of the current review is to identify and analyse existing evidence for PCOS as a metabolic, as well as a reproductive, disease.

Obesity-Related Hypogonadism in Women

Obesity-related hypogonadotropic hypogonadism is a well-characterized condition in men (termed male obesity-related secondary hypogonadism; MOSH); however, an equivalent condition has not been as clearly described in women. The prevalence of polycystic ovary syndrome (PCOS) is known to increase with obesity, but PCOS is more typically characterized by increased gonadotropin-releasing hormone (GnRH) (and by proxy luteinizing hormone; LH) pulsatility, rather than by the reduced gonadotropin levels observed in MOSH. Notably, LH levels and LH pulse amplitude are reduced with obesity, both in women with and without PCOS, suggesting that an obesity-related secondary hypogonadism may also exist in women akin to MOSH in men. Herein, we examine the evidence for the existence of a putative non-PCOS "female obesity-related secondary hypogonadism" (FOSH). We précis possible underlying mechanisms for the occurrence of hypogonadism in this context and consider how such mechanisms differ from MOSH in men, and from PCOS in women without obesity. In this review, we consider relevant etiological factors that are altered in obesity and that could impact on GnRH pulsatility to ascertain whether they could contribute to obesity-related secondary hypogonadism including: anti-Müllerian hormone, androgen, insulin, fatty acid, adiponectin, and leptin. More precise phenotyping of hypogonadism in women with obesity could provide further validation for non-PCOS FOSH and preface the ability to define/investigate such a condition.

Hyperinsulinemia impairs decidualization via AKT-NR4A1 signaling: new insight into polycystic ovary syndrome (PCOS)-related infertility

BACKGROUND

Investigating the underlying molecular mechanisms responsible for endometrial dysfunction in women with PCOS is essential, particularly focusing on the role of hyperinsulinemia.

METHODS

We explored the role of insulin in the decidualization process using a synthetic decidualization assay. To dissect the effects of PI3K/AKT-NR4A signaling, we employed small interfering RNAs (siRNAs) targeting the NR4A genes and inhibitors of the PI3K/AKT pathway. We also investigated the disruption of AKT-NR4A1 signaling in the endometrium of PCOS female rats induced with dehydroepiandrosterone (DHEA). Quantitative real-time PCR (qRT-PCR) and Western blot (WB) analyses were utilized to evaluate gene expression regulation.

RESULTS

Insulin was found to suppress the expression of decidualization markers in human endometrial stromal cells (hESC) in a dose-dependent manner, concurrently triggering an inappropriate activation of the PI3K/AKT pathway. Members of the NR4A family, as downstream effectors in the PI3K/AKT pathway, were implicated in the insulin-induced disruptions during the decidualization process. Moreover, the endometrium of PCOS models showed significantly elevated levels of phosphorylated (Ser473) AKT, with a corresponding reduction in Nr4a1 protein.

CONCLUSIONS

Our research demonstrates that insulin negatively regulates decidualization in hESC via the PI3K/AKT-NR4A pathway. In vivo analysis revealed a significant dysregulation of the AKT-NR4A1 pathway in the endometrium of PCOS rats. These findings offer novel insights into the pathogenesis of infertility and endometrial disorders associated with hyperinsulinemia in PCOS.

Metabolic hormones are integral regulators of female reproductive health and function

The female reproductive system is strongly influenced by nutrition and energy balance. It is well known that food restriction or energy depletion can induce suppression of reproductive processes, while overnutrition is associated with reproductive dysfunction. However, the intricate mechanisms through which nutritional inputs and metabolic health are integrated into the coordination of reproduction are still being defined. In this review, we describe evidence for essential contributions by hormones that are responsive to food intake or fuel stores. Key metabolic hormones-including insulin, the incretins (glucose-dependent insulinotropic polypeptide and glucagon-like peptide-1), growth hormone, ghrelin, leptin, and adiponectin-signal throughout the hypothalamic-pituitary-gonadal axis to support or suppress reproduction. We synthesize current knowledge on how these multifaceted hormones interact with the brain, pituitary, and ovaries to regulate functioning of the female reproductive system, incorporating in vitro and in vivo data from animal models and humans. Metabolic hormones are involved in orchestrating reproductive processes in healthy states, but some also play a significant role in the pathophysiology or treatment strategies of female reproductive disorders. Further understanding of the complex interrelationships between metabolic health and female reproductive function has important implications for improving women's health overall.

Exploring the role of irisin as a potential biomarker in adolescents and young adults with polycystic ovarian syndrome

BACKGROUND

Irisin is a myokine potentially linked to insulin sensitivity. Polycystic ovarian syndrome (PCOS) is a prevalent hormonal condition defined by insulin resistance. Previous studies have reported elevated circulating irisin levels in adult females with PCOS.

OBJECTIVE

To examine the differences in serum irisin levels between lean and obese adolescents and young adults with PCOS and their respective lean and obese controls and to explore the relationship between irisin levels and the metabolic and reproductive characteristics of the participants.

DESIGN

Cross-sectional study design.

METHODS

The study included 60 cases of PCOS and 60 controls. These participants were categorized based on their body mass index (BMI) into lean and obese. Fasting serum irisin levels, physical, metabolic, hormonal, and reproductive characteristics of the participants were measured.

RESULTS

Lean cases of PCOS had significantly elevated levels of fasting serum irisin (PCOS = 17.07 ± 5.61 ng/ml vs lean controls = 11.04 ± 7.51 ng/ml; p = 0.002), glucose, insulin, homeostasis model of assessment-insulin resistance index (HOMA-IR), luteinizing hormone (LH), estradiol, and testosterone and significantly lower levels of quantitative insulin sensitivity check index (QUICKI) compared to the lean controls. Obese cases of PCOS had significantly higher levels of fasting serum irisin (PCOS = 22.06 ± 3.83 ng/ml vs obese controls = 16.86 ± 6.74 ng/ml; p = 0.011), glucose, insulin, HOMA-IR, LH, estradiol, and testosterone and significantly lower levels of follicle-stimulating hormone (FSH) and QUICKI compared to obese controls. The findings revealed a significant positive correlation of serum irisin levels with BMI, glucose, insulin, HOMA-IR, LH, estradiol, and testosterone(all p-values < 0.001). There was also a significant positive correlation with triglycerides (TAGs) (p = 0.001), total cholesterol (p = 0.005), and low-density lipoprotein cholesterol (p = 0.024). Additionally, there was a significant negative correlation with high-density lipoprotein cholesterol (p = 0.001) and QUICKI (p < 0.001) in the entire study cohort. Fasting serum glucose (β = 0.337, p = 0.029), TAGs (β = 0.249, p = 0.006), and LH (β = 0.382, p = 0.004) were positive predictors of serum irisin concentrations in the overall sample.

CONCLUSION

Lean and obese adolescent and young adult cases of PCOS had significantly higher fasting serum irisin levels than their respective controls. Metabolic and reproductive traits of the participants also correlated with irisin.

Visfatin in the porcine pituitary gland: expression and regulation of secretion during the oestrous cycle and early pregnancy

Visfatin is a multifunctional protein which, besides the control of energy homeostasis, seems to be also involved in the regulation of female fertility through the influence on the endocrine hypothalamus-pituitary-gonadal axis, including the pituitary. The aim of this study was to investigate the expression of visfatin mRNA and protein in the anterior (AP) and posterior pituitary lobes of the pig during the oestrous cycle and early pregnancy. In AP, we also examined colocalisation of visfatin with pituitary tropic hormones. Moreover, we aimed to evaluate the in vitro effects of GnRH, FSH, LH, and insulin on visfatin protein concentration and secretion in AP cells during the cycle. The study showed that visfatin is present in all types of porcine pituitary endocrine cells and its expression is reliant on stage of the cycle or pregnancy. GnRH, FSH, LH and insulin stimulated visfatin secretion by AP cells on days 17 to 19 of the cycle, while on days 2 to 3 visfatin release was enhanced only by LH. Summarising, visfatin is locally produced in the pituitary in a way dependent on hormonal milieu typical for reproductive status of pigs. Further research is required to clarify the role of visfatin in the pituitary gland.

Impact of high-fat diet and exposure to constant light on reproductive competence of female ICR mice

Obesity and exposure to light at night are prevalent in modern society and associated with changes in physiology and behavior that can affect a female's ability to support offspring growth during pregnancy and lactation. A 2X3 factor study of ICR mice was conducted to determine the effect of diet [control (CON; 10% fat) or high fat (HF; 60% fat)] and exposure to regular 12 h light:dark cycles (LD) or continuous low (L5) or high (L100) lux of light on gestation length, birth litter size, milk composition and litter growth to lactation day 12. HF diet reduced birth litter size, but increased postnatal d 12 litter weight (P<0.05), whereas constant light tended to increase litter weight (P=0.07). Continuous light increased gestation length, altered dam feed intake, increased serum prolactin and increased final dam and mammary gland weight (P<0.05), while decreasing mammary ATP content and milk lactose (P<0.05). Correlation analysis indicated a positive relationship between final litter weight and mammary size, metabolic stores (e.g. maternal fat pad weight), kcal of feed intake, and gestation length (P<0.05). Although CON mice spent more time eating than HF dams, the calorically dense HF diet was related to greater rates of litter growth to peak lactation. Constant light circadian disrupting effects appear to be confounded by a potential long day photoperiod response exemplified by higher circulating levels of prolactin and increased body and mammary weight of females exposed to these conditions. Other model systems may be better to study the interacting effects of obesity and circadian disruption on reproductive competence.

Musashi Exerts Control of Gonadotrope Target mRNA Translation During the Mouse Estrous Cycle

The anterior pituitary controls key biological processes, including growth, metabolism, reproduction, and stress responses through distinct cell types that each secrete specific hormones. The anterior pituitary cells show a remarkable level of cell type plasticity that mediates the shifts in hormone-producing cell populations that are required to meet organismal needs. The molecular mechanisms underlying pituitary cell plasticity are not well understood. Recent work has implicated the pituitary stem cell populations and specifically, the mRNA binding proteins of the Musashi family in control of pituitary cell type identity. In this study we have identified the target mRNAs that mediate Musashi function in the adult mouse pituitary and demonstrate the requirement for Musashi function in vivo. Using Musashi RNA immunoprecipitation, we identify a cohort of 1184 mRNAs that show specific Musashi binding. Identified Musashi targets include the Gnrhr mRNA, which encodes the gonadotropin-releasing hormone receptor (GnRHR), and the Fshb mRNA, encoding follicle-stimulating hormone (FSH). Reporter assays reveal that Musashi functions to exert repression of translation of the Fshb mRNA, in addition to the previously observed repression of the Gnrhr mRNA. Importantly, mice engineered to lack Musashi in gonadotropes demonstrate a failure to repress translation of the endogenous Gnrhr and Fshb mRNAs during the estrous cycle and display a significant heterogeneity in litter sizes. The range of identified target mRNAs suggests that, in addition to these key gonadotrope proteins, Musashi may exert broad regulatory control over the pituitary proteome in a cell type-specific manner.

Liraglutide ameliorates diabetic-induced testicular dysfunction in male rats: role of GLP-1/Kiss1/GnRH and TGF-β/Smad signaling pathways

Introduction: Glucagon-like peptide -1 (GLP-1) is released by intestinal cells to stimulate glucose-dependent insulin release from the pancreas. GLP-1 has been linked to ameliorating obesity and/or diabetic complications as well as controlling reproductive function. Liraglutide is a GLP-1 receptor agonist (GLP-1RA) with 97% homology with GLP-1. The main objective of this study was to investigate the ameliorative role of liraglutide in diabetic-induced reproductive dysfunction in male rats. Methods: Rats were randomly allocated into 3 groups; a control group, a diabetic group, and a liraglutide-treated diabetic group. Results: In the diabetic group, a significant increase in BMI, FBG, HbA1c, HOMA-IR, TC, TAG, LDL, IL6, TNFα, and MDA, as well as decreased serum insulin, HDL, GSH, total testosterone, LH, and FSH, were shown compared to the control group. Furthermore, A significant downregulation in relative hypothalamic gene expression of GLP-1R, PPAR-α, PGC-1α, kiss, kiss1R, leptin, leptin R, GnRH GLP-1R, testicular PGC-1α, PPARα, kiss1, kiss1R, STAR, CYP17A1, HSD17B3, CYP19A, CYP11A1, and Smad7, as well as upregulation in hypothalamic GnIH and testicular TGF- β and Smad2 expression, were noticed compared to the control group. Liraglutide treatment significantly improved such functional and structural reproductive disturbance in diabetic rats. Conclusion: GLP-1RAs ameliorated the deleterious effects of diabetes on reproductive function by targeting GLP-1/leptin/kiss1/GnRH, steroidogenesis, and TGF- β/Smad pathways.

Sex Differences in Adipose Tissue Distribution Determine Susceptibility to Neuroinflammation in Mice With Dietary Obesity

Preferential energy storage in subcutaneous adipose tissue (SAT) confers protection against obesity-induced pathophysiology in females. Females also exhibit distinct immunological responses, relative to males. These differences are often attributed to sex hormones, but reciprocal interactions between metabolism, immunity, and gonadal steroids remain poorly understood. We systematically characterized adipose tissue hypertrophy, sex steroids, and inflammation in male and female mice after increasing durations of high-fat diet (HFD)-induced obesity. After observing that sex differences in adipose tissue distribution before HFD were correlated with lasting protection against inflammation in females, we hypothesized that a priori differences in the ratio of subcutaneous to visceral fat might mediate this relationship. To test this, male and female mice underwent SAT lipectomy (LPX) or sham surgery before HFD challenge, followed by analysis of glial reactivity, adipose tissue inflammation, and reproductive steroids. Because LPX eliminated female resistance to the proinflammatory effects of HFD without changing circulating sex hormones, we conclude that sexually dimorphic organization of subcutaneous and visceral fat determines susceptibility to inflammation in obesity.

Insulin resistance in polycystic ovary syndrome across various tissues: an updated review of pathogenesis, evaluation, and treatment

Polycystic ovary syndrome (PCOS) is a common endocrine disorder characterized by chronic ovulation dysfunction and overabundance of androgens; it affects 6-20% of women of reproductive age. PCOS involves various pathophysiological factors, and affected women usually have significant insulin resistance (IR), which is a major cause of PCOS. IR and compensatory hyperinsulinaemia have differing pathogeneses in various tissues, and IR varies among different PCOS phenotypes. Genetic and epigenetic changes, hyperandrogenaemia, and obesity aggravate IR. Insulin sensitization drugs are a new treatment modality for PCOS. We searched PubMed, Google Scholar, Elsevier, and UpToDate databases in this review, and focused on the pathogenesis of IR in women with PCOS and the pathophysiology of IR in various tissues. In addition, the review provides a comprehensive overview of the current progress in the efficacy of insulin sensitization therapy in the management of PCOS, providing the latest evidence for the clinical treatment of women with PCOS and IR.

Obesity enhances antiviral immunity in the genital mucosa through a microbiota-mediated effect on γδ T cells

Obesity is detrimental to the immune system. It impairs lymphatics, T cell development, and lymphopoiesis; induces dysfunction of antitumor immunity; and also promotes tumor progression. However, direct evidence of the impact of obesity on viral infection is lacking. We report a protective role of obesity against herpes simplex virus 2 infection of the genital mucosa in mice. Although conventional antiviral immunity is comparable between obese mice and lean mice, obesity enhances the cytotoxic subset of γδ T cells. This effect is mediated by L-arginine produced by commensal microbiota in the genital mucosa, which induces "pseudonormoxia" of γδ T cells, resulting in increased natural killer (NK) group 2 D (NKG2D) expression of γδ T cells through the downregulation of hypoxia-inducible factor 1-alpha (HIF1A) by inducing nitric oxide (NO) production, thereby protecting mice from lethal genital herpes. Thus, our work illuminates one mechanism by which obesity-induced compositional changes in the vaginal microbiota can affect mucosal immune responses against viral infection.

Sodium-glucose cotransporter 2 inhibitor ameliorates high fat diet-induced hypothalamic-pituitary-ovarian axis disorders

High-fat diet (HFD) consumption is known to be associated with ovulatory disorders among women of reproductive age. Previous studies in animal models suggest that HFD-induced microglia activation contributes to hypothalamic inflammation. This causes the dysfunction of the hypothalamic-pituitary-ovarian (HPO) axis, leading to subfertility. Sodium-glucose cotransporter 2 (SGLT2) inhibitors are a novel class of lipid-soluble antidiabetic drugs that target primarily the early proximal tubules in kidney. Recent evidence revealed an additional expression site of SGLT2 in the central nervous system (CNS), indicating a promising role of SGLT2 inhibitors in the CNS. In type 2 diabetes patients and rodent models, SGLT2 inhibitors exhibit neuroprotective properties through reduction of oxidative stress, alleviation of cerebral atherosclerosis and suppression of microglia-induced neuroinflammation. Furthermore, clinical observations in patients with polycystic ovary syndrome (PCOS) demonstrated that SGLT2 inhibitors ameliorated patient anthropometric parameters, body composition and insulin resistance. Therefore, it is of importance to explore the central mechanism of SGLT2 inhibitors in the recovery of reproductive function in patients with PCOS and obesity. Here, we review the hypothalamic inflammatory mechanisms of HFD-induced microglial activation, with a focus on the clinical utility and possible mechanism of SGLT2 inhibitors in promoting reproductive fitness.

Obesity: A Doorway to a Molecular Path Leading to Infertility

The dramatic rise in obesity has recently made it a global health issue. About 1.9 billion were overweight, and 650 million global populations were obese in 2016. Obese women suffer longer conception time, lowered fertility rates, and greater rates of miscarriage. Obesity alters hormones such as adiponectin and leptin, affecting all levels within the hypothalamic-pituitary-gonadal axis. Advanced glycation end products (AGEs) and monocyte chemotactic protein-1 (MCP-1) are inflammatory cytokines that may play an important role in the pathophysiology of ovarian dysfunction in obesity. In obese males, there are altered sperm parameters, reduced testosterone, increased estradiol, hypogonadism, and epigenetic modifications transmitted to offspring. The focus of this article is on the possible adverse effects on reproductive health resulting from obesity and sheds light on different molecular pathways linking obesity with infertility in both female and male subjects. Electronic databases such as Google Scholar, Embase, Science Direct, PubMed, and Google Search Engine were utilized to find obesity and infertility-related papers. The search strategy is detailed in the method section. Even though multiple research work has shown that obesity impacts fertility in both male and female negatively, it is significant to perform extensive research on the molecular mechanisms that link obesity to infertility. This is to find therapeutics that may be developed aiming at these mechanisms to manage and prevent the negative effects of obesity on the reproductive system.

Hyperinsulinemia induces early and dyssynchronous puberty in lean female mice

Girls with obesity are at increased risk of early puberty. Obesity is associated with insulin resistance and hyperinsulinemia. We hypothesized that insulin plays a physiological role in pubertal transition, and super-imposed hyperinsulinemia due to childhood obesity promotes early initiation of puberty in girls. To isolate the effect of hyperinsulinemia from adiposity, we compared pre-pubertal and pubertal states in hyperinsulinemic, lean muscle (M)-insulin-like growth factor 1 receptor (IGF-1R)-lysine (K)-arginine (R) (MKR) mice to normoinsulinemic WT, with puberty onset defined by vaginal opening (VO). Our results show MKR had greater insulin resistance and higher insulin levels (P < 0.05) than WT despite lower body weight (P < 0.0001) and similar IGF-1 levels (P = NS). Serum luteinizing hormone (LH) levels were higher in hyperinsulinemic MKR (P = 0.005), and insulin stimulation induced an increase in LH levels in WT. VO was earlier in hyperinsulinemic MKR vs WT (P < 0.0001). When compared on the day of VO, kisspeptin expression was higher in hyperinsulinemic MKR vs WT (P < 0.05), and gonadotropin-releasing hormone and insulin receptor isoform expression was similar (P = NS). Despite accelerated VO, MKR had delayed, disordered ovarian follicle and mammary gland development. In conclusion, we found that hyperinsulinemia alone without adiposity triggers earlier puberty. In our study, hyperinsulinemia also promoted dyssynchrony between pubertal initiation and progression, urging future studies in girls with obesity to assess alterations in transition to adulthood.

Rescue of obesity-induced infertility in female mice by silencing AgRP neurons

Obesity impacts multiple sites of the hypothalamus-pituitary gland-ovary axis (HPO axis) and has become a leading cause of female infertility. However, the critical hypothalamic neurons that participate in the development of obesity-induced infertility have not been well defined yet. Previous studies suggested that metabolic-sensing agouti-related peptide-expressing (AgRP) neurons in the arcuate nucleus (ARC) are hyperactive in diet-induced obesity (DIO) mice. We hypothesize that these neurons may convey metabolic dysfunction onto the HPO axis and contribute to obesity-induced infertility's pathophysiological process. To determine if AgRP neurons in obesity play a necessary role in the development of reproductive impairment in obesity, we used the chemogenetic method to normalize the neuronal activity of AgRP neurons in DIO female mice and test if their fertility can be restored. Our results indicated that chemogenetic inhibition of AgRP neurons could fully rescue the reproductive performance of DIO female mice, as manifested by recovered sex hormonal levels, ovulation, and fecundity. Moreover, we assayed serum AgRP levels in normal-weight and obese women and found elevated AgRP levels in obese subjects, suggesting the correlation between obesity and AgRP neuronal hyperactivity. Our results indicated that AgRP neurons constitute a central node connecting metabolism and reproduction, and dysfunctions of these neurons play a crucial role in reproductive impairment induced by metabolic abnormalities.

Lower FSH With Normal Fertility in Male Mice Lacking Gonadotroph Kisspeptin Receptor

The kisspeptin receptor, crucial for hypothalamic control of puberty and reproduction, is also present in the pituitary gland. Its role in the pituitary gland is not defined. Kisspeptin signaling via the Kiss1r could potentially regulate reproductive function at the level of pituitary gonadotrope. Using Cre/Lox technology, we deleted the Kiss1r gene in pituitary gonadotropes (PKiRKO). PKiRKO males have normal genital development (anogenital distance WT: 19.1 ± 0.4 vs. PKiRKO: 18.5 ± 0.4 mm), puberty onset, testes cell structure on gross histology, normal testes size, and fertility. PKiRKO males showed significantly decreased serum FSH levels compared to WT males (5.6 ± 1.9 vs. 10.2 ± 1.8 ng/ml) with comparable LH (1.1 ± 0.2 vs. 1.8 ± 0.4 ng/ml) and testosterone levels (351.8 ± 213.0 vs. 342.2 ± 183.0 ng/dl). PKiRKO females have normal puberty onset, cyclicity, LH and FSH levels and fertility. Overall, these findings indicate that absence of pituitary Kiss1r reduces FSH levels in male mice without affecting testis function. PKiRKO mice have normal reproductive function in both males and females.

Diet-induced maternal obesity impacts feto-placental growth and induces sex-specific alterations in placental morphology, mitochondrial bioenergetics, dynamics, lipid metabolism and oxidative stress in mice

AIM

The current study investigated the impact of maternal obesity on placental phenotype in relation to fetal growth and sex.

METHODS

Female C57BL6/J mice were fed either a diet high in fat and sugar or a standard chow diet, for 6 weeks prior to, and during, pregnancy. At day 19 of gestation, placental morphology and mitochondrial respiration and dynamics were assessed using high-resolution respirometry, stereology, and molecular analyses.

RESULTS

Diet-induced maternal obesity increased the rate of small for gestational age fetuses in both sexes, and increased blood glucose concentrations in offspring. Placental weight, surface area, and maternal blood spaces were decreased in both sexes, with reductions in placental trophoblast volume, oxygen diffusing capacity, and an increased barrier to transfer in males only. Despite these morphological changes, placental mitochondrial respiration was unaffected by maternal obesity, although the influence of fetal sex on placental respiratory capacity varied between dietary groups. Moreover, in males, but not females, maternal obesity increased mitochondrial complexes (II and ATP synthase) and fission protein DRP1 abundance. It also reduced phosphorylated AMPK and capacity for lipid synthesis, while increasing indices of oxidative stress, specifically in males. In females only, placental mitochondrial biogenesis and capacity for lipid synthesis, were both enhanced. The abundance of uncoupling protein-2 was decreased by maternal obesity in both fetal sexes.

CONCLUSION

Maternal obesity exerts sex-dependent changes in placental phenotype in association with alterations in fetal growth and substrate supply. These findings may inform the design of personalized lifestyle interventions or therapies for obese pregnant women.

Effects of hypercaloric diet-induced hyperinsulinemia and hyperlipidemia on the ovarian follicular development in mice

Long-term hypercaloric diets may adversely affect the development of ovarian follicles. We investigated the effects of high sugar (HS), high fat low sugar (HFLS), and high fat normal sugar (HFNS) diets on the ovarian follicle development in mice fed with these diets as compared to those fed with normal diet (control) for 180 days. Body weight, gonadal fat, glucose, lipid, insulin, estrous cycle, sex hormones and ovarian tissues were examined, and metabolism-related protein expression in the ovaries was evaluated by immunoblotting. The mice fed with hypercaloric diets showed hyperinsulinemia and hyperlipidemia, and exhibited heavier body and gonadal fat weights, longer estrous cycles, and fewer preantral and antral follicles than mice fed with normal diet. The sex hormone levels in the blood were similar to those in controls, except for significantly elevated estradiol levels in the HS diet group. The AMPKα phosphorylation was reduced, while AKT phosphorylation and caspase-3 levels were increased in the ovarian tissues of mice in all three hypercaloric diet groups than those in control. Taken together, the results suggest hyperinsulinemia and hyperlipidemia as possible mechanisms that impair the development of ovarian follicles in response to long-term exposure to unhealthy hypercaloric diets.

Hypothalamic mechanisms of obesity-associated disturbance of hypothalamic-pituitary-ovarian axis

Ovulatory disorders are the most common clinical feature exhibited among obese women. Initiation of ovulation physiologically requires a surge of gonadotropin-releasing hormone (GnRH) released from GnRH neurons located in the hypothalamus. These GnRH neurons receive metabolic signals from circulation and vicinal neurons to regulate GnRH release. Leptin acts indirectly on GnRH via adjacent leptin receptor (LEPR)-expressing neurons such as proopiomelanocortin (POMC), neuropeptide Y (NPY)/agouti-related peptide (AgRP), and neuronal nitric oxide (NO) synthase (nNOS) neurons to affect GnRH neuronal activities. Additionally, hypothalamic inflammation also affects ovulation independent of obesity. Therefore, this review focuses on hypothalamic mechanisms that underlie the disturbance of hypothalamic-pituitary-ovarian (HPO) axis during obesity with an attempt to promote future studies and/or novel therapeutic strategies for ovulatory disorders in obesity.

Disruption of Pituitary Gonadotrope Activity in Male Rats After Short- or Long-Term High-Fat Diets Is Not Associated With Pituitary Inflammation

Overnutrition is associated with the activation of inflammatory pathways in metabolically linked organs and an early hypothalamic inflammation is now known to disrupt the central control of metabolic function. Because we demonstrated that fatty acids (FA) target the pituitary and affect gonadotropin synthesis, we asked whether overnutrition induces pituitary inflammation that may contribute to obesity-associated disorders in the control of reproduction. We analyzed pituitary inflammation and hypothalamic-pituitary-testicular axis in male rats fed a short- (4 weeks) or long-term (20 weeks) high-fat diet. The effect of diet enrichment with the ω3 polyunsaturated FA, DHA, was also analyzed. After only 4 weeks and before weight gain of rats, high-fat diet caused a significant decrease in pituitary gonadotropin and hypothalamic GnRH transcript levels despite unchanged testosterone and inhibin B levels. Contrasting with the hypothalamus, there was no concomitant increases in gene expression of pituitary inflammatory mediators and even a reduction of prototypical cytokines such as interleukin-1β and TNF-α. No inflammation was still detected in the pituitary after 20 weeks although gonadotropin transcripts and circulating levels were still altered. Gonadotropins were the only pituitary hormones remaining affected at this stage of the regimen, underlying a differential susceptibility of pituitary lineages to metabolic disorders. DHA enrichment of the diet did not prevent alterations of gonadotrope activity due to either a long- or a short-term high-fat diet although it blocked early hypothalamic inflammation and attenuated several metabolic effects. Taken together, our findings suggest that high-fat diet-induced defects in gonadotrope activity in male rats occurred despite a lack of pituitary inflammation.

Impact of body mass index (BMI) on the success rate of fresh embryo transfer in women undergoing first in vitro fertilization/intracytoplasmic sperm injection (IVF/ICSI) treatment

OBJECTIVE

To investigate the impact of body mass index (BMI) on the success rate and prenatal outcomes of fresh embryo transfer in women undergoing their first in vitro fertilization/intracytoplasmic sperm injection (IVF/ICSI) treatment.

METHODS

It is a post-hoc analysis of a prospective observational cohort study. 2569 Chinese women were grouped in quintiles of BMI and according to the official Chinese classification of body weight. IVF/ICSI and pregnancy outcomes were compared between groups.

RESULTS

BMI was not associated with IVF/ICSI pregnancy outcomes including hCG positive rate, clinical pregnancy rate, implantation rate, ectopic pregnancy rate, ongoing pregnancy rate, early miscarriage rate, and live birth rate. However, it was negatively related to some pregnancy complications such as gestational diabetes mellitus (GDM) and hypertension. Additionally, the proportion of Cesarean-section was increased with BMI. As for prenatal outcomes, the current results showed no statistical difference in the number of male and female newborn, the proportion of low live birth weight (<2500 g), macrosomia (≥4000 g) (both in all live birth and full-term live birth), and premature delivery (<37 weeks).

CONCLUSIONS

The current study showed that BMI was not associated with embryo transfer outcomes after fresh embryo transfer in women undergoing their first IVF/ICSI treatment, whereas BMI was associated with GDM and gestational hypertension.

Obesity induces morphological and functional changes in female reproductive system through increases in NF-κB and MAPK signaling in mice

BACKGROUND

Recently, human infertility incidence is increasing in obese women causing it to become an emerging global health challenge requiring improved treatment. There is extensive evidence that obesity caused female reproductive dysfunction is accompanied by an endocrinological influence. Besides, systemic and tissue-specific chronic inflammatory status are common characteristics of obesity. However, the underlying molecular mechanism is unclear linking obesity to infertility or subfertility.

METHODS

To deal with this question, we created an obese mouse model through providing a high fat diet (HFD) and determined the fertility of the obese mice. The morphological alterations were evaluated in both the reproductive glands and tracts, such as uterus, ovary and oviduct. Furthermore, to explore the underlying mechanism of these functional changes, the expressions of pro-inflammatory cytokines as well as the activations of MAPK signaling and NF-κB signaling were detected in these reproductive tissues.

RESULTS

The obese females were successful construction and displayed subfertility. They accumulated lipid droplets and developed morphological alterations in each of their reproductive organs including uterus, ovary and oviduct. These pathological changes accompanied increases in pro-inflammatory cytokine expression levels of interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) in all of these sites. Such effects also accompanied increases in nuclear factor kappa B (NF-kB) expression and mitogen-activated protein kinase (MAPK) signaling pathway stimulation based on uniform time dependent increases in the NF-κB (p-NF-κB), JNK (p-JNK), ERK1/2 (p-ERK) and p38 (p-p38) phosphorylation status.

CONCLUSIONS

These HFD-induced increases in pro-inflammatory cytokine expression levels and NF-κB and MAPKs signaling pathway activation in reproductive organs support the notion that increases of adipocytes resident and inflammatory status are symptomatic of female fertility impairment in obese mice.

Pituitary P62 deficiency leads to female infertility by impairing luteinizing hormone production

P62 is a protein adaptor for various metabolic processes. Mice that lack p62 develop adult-onset obesity. However, investigations on p62 in reproductive dysfunction are rare. In the present study, we explored the effect of p62 on the reproductive system. P62 deficiency-induced reproductive dysfunction occurred at a young age (8 week old). Young systemic p62 knockout (p62-/-) and pituitary-specific p62 knockout (p62flox/flox αGSUcre) mice both presented a normal metabolic state, whereas they displayed infertility phenotypes (attenuated breeding success rates, impaired folliculogenesis and ovulation, etc.) with decreased luteinizing hormone (LH) expression and production. Consistently, in an infertility model of polycystic ovary syndrome (PCOS), pituitary p62 mRNA was positively correlated with LH levels. Mechanistically, p62-/- pituitary RNA sequencing showed a significant downregulation of the mitochondrial oxidative phosphorylation (OXPHOS) pathway. In vitro experiments using the pituitary gonadotroph cell line LβT2 and siRNA/shRNA/plasmid confirmed that p62 modulated LH synthesis and secretion via mitochondrial OXPHOS function, especially Ndufa2, a component molecule of mitochondrial complex I, as verified by Seahorse and rescue tests. After screening OXPHOS markers, Ndufa2 was found to positively regulate LH production in LβT2 cells. Furthermore, the gonadotropin-releasing hormone (GnRH)-stimulating test in p62flox/flox αGSUcre mice and LβT2 cells illustrated that p62 is a modulator of the GnRH-LH axis, which is dependent on intracellular calcium and ATP. These findings demonstrated that p62 deficiency in the pituitary impaired LH production via mitochondrial OXPHOS signaling and led to female infertility, thus providing the GnRH-p62-OXPHOS(Ndufa2)-Ca2+/ATP-LH pathway in gonadotropic cells as a new theoretical basis for investigating female reproductive dysfunction.

Aging mitigates the severity of obesity-associated metabolic sequelae in a gender independent manner

BACKGROUND

Understanding gender-associated bias in aging and obesity-driven metabolic derangements has been hindered by the inability to model severe obesity in female mice.

METHODS

Here, using chow- or high fat diet (HFD)-feeding regimens at standard (TS) and thermoneutral (TN) housing temperatures, the latter to model obesity in female mice, we examined the impact of gender and aging on obesity-associated metabolic derangements and immune responsiveness. Analysis included quantification of: (i) weight gain and adiposity; (ii) the development and severity of glucose dysmetabolism and non-alcoholic fatty liver disease (NAFLD); and (iii) induction of inflammatory pathways related to metabolic dysfunction.

RESULTS

We show that under chow diet feeding regimen, aging was accompanied by increased body weight and white adipose tissue (WAT) expansion in a gender independent manner. HFD feeding regimen in aged, compared to young, male mice at TS, resulted in attenuated glucose dysmetabolism and hepatic steatosis. However, under TS housing conditions only aged, but not young, HFD fed female mice developed obesity. At TN however, both young and aged HFD fed female mice developed severe obesity. Independent of gender or housing conditions, aging attenuated the severity of metabolic derangements in HFD-fed obese mice. Tempered severity of metabolic derangements in aged mice was associated with increased splenic frequency of regulatory T (Treg) cells, Type I regulatory (Tr1)-like cells and circulating IL-10 levels and decreased vigor of HFD-driven induction of inflammatory pathways in adipose and liver tissues.

CONCLUSION

Our findings suggest that aging-associated altered immunological profile and inflammatory vigor may play a dominant role in the attenuation of obesogenic diet-driven metabolic dysfunction.

Post-Transcriptional Regulation of Gnrhr: A Checkpoint for Metabolic Control of Female Reproduction

The proper expression of gonadotropin-releasing hormone receptors (GnRHRs) by pituitary gonadotropes is critical for maintaining maximum reproductive capacity. GnRH receptor expression must be tightly regulated in order to maintain the normal pattern of expression through the estrous cycle in rodents, which is believed to be important for interpreting the finely tuned pulses of GnRH from the hypothalamus. Much work has shown that Gnrhr expression is heavily regulated at the level of transcription. However, researchers have also discovered that Gnrhr is regulated post-transcriptionally. This review will discuss how RNA-binding proteins and microRNAs may play critical roles in the regulation of GnRHR expression. We will also discuss how these post-transcriptional regulators may themselves be affected by metabolic cues, specifically with regards to the adipokine leptin. All together, we present evidence that Gnrhr is regulated post-transcriptionally, and that this concept must be further explored in order to fully understand the complex nature of this receptor.

Obesity alters ovarian folliculogenesis through disrupted angiogenesis from increased IL-10 production

Objective

Obesity has been reported to have a modulatory effect on the ovulatory functions of patients with polycystic ovary syndrome. The role of adipokines in this obesity-associated ovulatory disturbance has not been extensively explored. In this study, the relationships between obesity, adipokine production from visceral fat, and ovarian folliculogenesis were explored in a mice model of induced obesity.

Methods

Obesity was induced in female C57BL/6 mice fed ad libitum with high-fat feed and fructose water for 4 weeks. Follicular developments in the ovaries were assessed by histopathology in these diet-induced obese mice. Changes in adipokine expression in the peri-ovarian adipose tissues were screened with an adipokine array. The adipokine with the most significant increase over time was identified. The functions of the adipokine in angiogenic processes were evaluated in a cell model of endothelial proliferation. The in vivo effects of neutralizing this adipokine using specific antibodies were assessed in the same obesity model.

Results

A high-fat and fructose diet induced an accumulation of early ovarian follicles and a reduction in mature follicles and corpus lutea. The number of microvessels in the early follicles also decreased. The adipokine protein array of the peri-ovarian adipose tissues identified a progressive increase in IL-10 expression with the duration of the obesogenic diet. In vitro experiments in the endothelial cell model confirmed IL-10 as a disrupter of VEGF-induced angiogenesis. Administration of anti-IL-10 antibodies prevented the histopathological changes induced by the obesogenic diet and further highlighted the role of IL-10 in disrupting folliculogenesis.

Conclusions

Obesity may disrupt normal folliculogenesis through increased production of IL-10 in visceral fats. This relationship may help clarify the reported association between obesity and ovulatory dysfunction, which has been found in patients with polycystic ovary syndrome. However, the duration of this study was short, which limited conclusions on the long-term reproductive outcomes.

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Obesity increases IL-10 expression in visceral adipose.

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IL-10 disrupts VEGF-induced angiogenesis in an endothelial cell model.

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Disrupted angiogenesis is associated with disturbed folliculogenesis.

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Anti-IL-10 antibody prevents the altered folliculogenesis induced by obesity.

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Abnormal production of IL-10 may be a cause of dysovulation in obese individuals.

Role of insulin in the neuroendocrine control of reproduction

Infertility associated with insulin resistance is characterised by abnormal hormone secretion by the hypothalamus, pituitary gland and gonads. These endocrine tissues can maintain insulin sensitivity even when tissues such as the muscle and liver become insulin-resistant, resulting in excessive insulin stimulation as hyperinsulinaemia develops. Experiments conducted to determine the role of neuronal insulin signalling in fertility were unable to recapitulate early findings of hypogonadotrophic hypogonadism in mice lacking insulin receptors throughout the brain. Rather, it was eventually shown that astrocytes critically mediate the effects of insulin on puberty timing and adult reproductive function. However, specific roles for neurones and gonadotrophs have been revealed under conditions of hyperinsulinaemia and by ablation of insulin and leptin receptors. The collective picture is one of multiple insulin-responsive inputs to gonadotrophin releasing hormone neurones, with astrocytes being the most important player.

Effects of metformin on body weight in polycystic ovary syndrome patients: model-based meta-analysis

OBJECTIVES

The present study aimed to investigate the effects of metformin on body weight in polycystic ovary syndrome (PCOS) patients by model-based meta-analysis (MBMA).

METHODS

Randomized controlled trial (RCT) studies of metformin in treatment of PCOS patients were collected and efficacy indicators were the body mass index (BMI) change rates from baseline.

RESULTS

28 RCT studies, 1631 PCOS patients were included for analysis. Model of metformin monotherapy, and model of metformin combination therapy were established, respectively. After deducting control group effects, the E_max of metformin on BMI were -5.88% and -11.8% in metformin monotherapy and metformin combination therapy, respectively. In order to play better curative effects, for metformin monotherapy, 1000 mg/day metformin needs for at least 25.5 weeks; For metformin combination therapy, 1000 mg/day metformin needs for at least 58.6 weeks.

CONCLUSION

It was the first time to quantify the effects of metformin on body weight and recommend dose and duration for metformin monotherapy and metformin combination therapy in PCOS patients.

Vitamin D and Polycystic Ovary Syndrome: a Narrative Review

Polycystic ovary syndrome (PCOS) is one of the most common endocrine disorders of reproductive age women and contributes to metabolic dysfunctions including insulin resistance (IR) and dyslipidemia. Vitamin D is a steroid hormone, which is involved in calcium metabolism and bone structure and has a potential role in the prevention of many illnesses, including cancers, autoimmune disorders, hypertension, diabetes, and obesity. Recently, it has been reported that vitamin D deficiency was a common complication of PCOS and vitamin D status was associated with reproductive ability, metabolic alterations, and mental health of PCOS patients. This review summarizes the advances between vitamin D status and the pathophysiological process of PCOS. Vitamin D level was negatively associated with serum androgen level. Vitamin D treatment could reduce serum androgen and anti-MüllerianHormone (AMH) levels, and decrease endometrial thickness, which resulted in improvement of menstrual cycle and folliculogenesis of PCOS patients. Moreover, vitamin D concentrations were negatively correlated with parameters of IR and body fat mass. Vitamin D supplementation has beneficial effects on IR and lipid metabolism. In addition, a positive of vitamin D on mental health of PCOS patients was proposed. Understanding the relationship between vitamin D status and the symptoms of PCOS patients is of great clinical significance to treat and prevent the progression of PCOS.

Recovery of menses after functional hypothalamic amenorrhoea: if, when and why

BACKGROUND

Prolonged amenorrhoea occurs as a consequence of functional hypothalamic amenorrhoea (FHA) which is most often induced by weight loss, vigorous exercise or emotional stress. Unfortunately, removal of these triggers does not always result in the return of menses. The prevalence and conditions underlying the timing of return of menses vary strongly and some women report amenorrhoea several years after having achieved and maintained normal weight and/or energy balance. A better understanding of these factors would also allow improved counselling in the context of infertility. Although BMI, percentage body fat and hormonal parameters are known to be involved in the initiation of the menstrual cycle, their role in the physiology of return of menses is currently poorly understood. We summarise here the current knowledge on the epidemiology and physiology of return of menses.

OBJECTIVE AND RATIONALE

The aim of this review was to provide an overview of (i) factors determining the recovery of menses and its timing, (ii) how such factors may exert their physiological effects and (iii) whether there are useful therapeutic options to induce recovery.

SEARCH METHODS

We searched articles published in English, French or German language containing keywords related to return of menses after FHA published in PubMed between 1966 and February 2020. Manuscripts reporting data on either the epidemiology or the physiology of recovery of menses were included and bibliographies were reviewed for further relevant literature. The Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) criteria served to assess quality of observational studies.

OUTCOMES

Few studies investigate return of menses and most of them have serious qualitative and methodological limitations. These include (i) the lack of precise definitions for FHA or resumption of menses, (ii) the use of short observation periods with unsatisfactory descriptions and (iii) the inclusion of poorly characterised small study groups. The comparison of studies is further hampered by very inhomogeneous study designs. Consequently, the exact prevalence of resumption of menses after FHA is unknown. Also, the timepoint of return of menses varies strongly and reliable prediction models are lacking. While weight, body fat and energy availability are associated with the return of menses, psychological factors also have a strong impact on the menstrual cycle and on behaviour known to increase the risk of FHA. Drug therapies with metreleptin or naltrexone might represent further opportunities to increase the chances of return of menses, but these require further evaluation.

WIDER IMPLICATIONS

Although knowledge on the physiology of return of menses is presently rudimentary, the available data indicate the importance of BMI/weight (gain), energy balance and mental health. The physiological processes and genetics underlying the impact of these factors on the return of menses require further research. Larger prospective studies are necessary to identify clinical parameters for accurate prediction of return of menses as well as reliable therapeutic options.

High-Fat Diet Alters LH Secretion and Pulse Frequency in Female Mice in an Estrous Cycle-Dependent Manner

Reproductive fitness in females is susceptible to obesogenic diets. Energy balance and reproduction are tightly regulated, in part, by hypothalamic neurons in the arcuate nucleus (ARC), and high-fat diet (HFD) can steadily increase estradiol levels in rodents. Estradiol regulates the reproductive axis via negative feedback mechanisms in ARC neurons by modulating pulsatile release of the gonadotropin luteinizing hormone (LH). However, it is unclear how the circulating estradiol milieu of adult females interacts with a state of high-caloric fat intake to alter LH pulse dynamics. Here, we used serial tail-tip blood sampling to measure pulsatile LH release at different estrous cycle stages in mice fed a HFD. Starting at 21 days of age, female C57BL/6J mice were freely fed with either regular chow diet (RD) or 60% kcal HFD for 12 weeks. Blood samples were collected once at diestrus, and then again at estrus. LH was measured in 10-minute intervals for 3 hours and analyzed for pulse frequency, amplitude, and mean and basal LH levels. Compared with RD-fed controls, mice fed HFD displayed significantly increased pulse frequency at diestrus, but not at estrus. HFD-fed mice also had lower mean and basal LH levels compared with RD-fed controls, but only during estrus. These data suggest that circulating estradiol can variably contribute to the impact that HFD has on LH pulsatile release and also provide insight into how obesity impacts women's reproductive health when ovarian estradiol levels drastically change, such as during menopause or with hormone replacement therapy.

Removal of DHT can relieve polycystic ovarian but not metabolic abnormalities in DHT-induced hyperandrogenism in mice

Polycystic ovary syndrome (PCOS) is an endocrine disorder with a high prevalence in women of childbearing age. To date, there is no method of efficiently diagnosing PCOS and curing it completely because its pathomechanism remains unclear. Here, we investigated whether metabolic abnormalities maintain the hyperandrogenism and PCOS-like ovaries and whether the symptoms induced by excess androgen are treatable. We ceased the abnormal dihydrotestosterone (DHT) stimulation to determine changes in PCOS-like mice. After ceasing DHT stimulation, the ovarian morphology and gene expression recovered from the DHT-stimulated status. However, after cessation of DHT stimulation, the hypertrophy of adipose tissues and hepatic steatosis were not significantly restored, and fat accumulation-related gene expression and serum metabolic markers in the mice were altered. These findings showed that the reproductive dysfunction was obviously relieved, but because the metabolic abnormalities were not relieved after the cessation of excess androgen for 30 days, it appears that the latter may not maintain the former.

Systems Pharmacology-Based Research on the Mechanism of Tusizi-Sangjisheng Herb Pair in the Treatment of Threatened Abortion

Threatened abortion (TA) is a common complication with high incidence in the first trimester of pregnancy, which will end in miscarriage if not treated properly. The Chinese herbs Cuscutae Semen (Tusizi in Chinese) and Herba Taxilli (Sangjisheng in Chinese) first recorded in the ancient classic medical book Shennong Bencao Jing are effective and widely used as an herb pair for the treatment of TA, while the active ingredients and the functional mechanism of Tusizi-Sangjisheng herb pair treating TA are still unknown. In order to exploit the relationship between those two herbs and TA, systems pharmacology analysis was carried out in this study. A total of 75 ingredients of Tusizi-Sangjisheng were collected from Traditional Chinese Medicine System Pharmacology Database and Analysis Platform (TCMSP). 12 bioactive compounds were screened, and 153 directly related targets were predicted by systematic models. Besides, Gene Ontology (GO) enrichment analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis were used to systematically explore the potential mechanisms of Tusizi-Sangjisheng treating TA. Meanwhile, Compound-Target (C-T), Target-Disease (T-D), and Target-Pathway (T-P) networks were constructed to further quest the underlying functional mechanisms of Tusizi-Sangjisheng. As a result, 31 targets and 3 key pathways were found to be directly related to TA that includes mitogen-activated protein kinases (MAPKs), phosphatidylinositol-3-kinase/protein kinase B (PI3K-Akt), and transforming growth factor-β (TGF-β) signaling pathways. The results in this study may provide some valuable clues about the molecular mechanisms of the efficient Chinese herb pair Tusizi-Sangjisheng in the treatment of TA.

Short-term but not long-term high-fat diet induces an increase in gene expression of gonadotropic hormones and GPR120 in the male mouse pituitary gland

High-fat diet (HFD) is associated with the regulation of reproductive functions. This study aimed to investigate the effects of short-term HFD on the mRNA expression levels of follicle-stimulating hormone β subunit (FSHβ), luteinizing hormone β subunit (LHβ), gonadotropin-releasing hormone receptor, and long-chain fatty acid receptor, GPR120, in the matured male mouse pituitary gland. Adult male mice were fed either control chow or HFD for 1, 2, 5, 10, 30 and 150 days. Fshb and Gpr120 mRNA expression levels in the pituitary glands were significantly increased during 2 to 30 days of HFD feeding. Gnrh-r mRNA in the 30 days HFD fed group and body weight in the 30 and 150 days HFD fed groups were higher than control. However, there were no significant differences in plasma non-esterified fatty acids or glucose levels during the 150 days of HFD feeding. These results suggest that male mice feeding a short-term HFD induces FSHβ synthesis and GPR120 expression in their pituitary gonadotropes.

The Effect of Berberine on Reproduction and Metabolism in Women with Polycystic Ovary Syndrome: A Systematic Review and Meta-Analysis of Randomized Control Trials

Purpose

To assess the efficacy and safety of berberine on reproductive endocrine and metabolic outcomes in women with polycystic ovary syndrome (PCOS).

Methods

PubMed (from 1950), the Cochrane Library, the CNKI (from 1979), the VIP (from 1989), and the Wanfang Data (from 1990) and the reference lists of the retrieved articles were searched for randomized controlled trials in human beings with the search terms including "polycystic ovary syndrome/PCOS" and "berberine/BBR/Huangliansu (in Chinese)/Xiao bojian (in Chinese)" till 30 May 2019. Relevant indicators were collected and the data were analyzed by using RevMan 5.3 software.

Results

Eventually, a total of 12 randomized controlled trials were included in this systematic review. Our study suggested that berberine had similar live birth rates compared with placebo or metformin and lower live birth rates (RR: 0.61, 95% CI: 0.44 to 0.82) compared with letrozole. There was a significant difference between berberine and placebo and between berberine and no treatment in terms of decreasing total testosterone and luteinizing hormone to follicle-stimulating hormone (LH/FSH) ratio (8 RCTs, 577 participants, MD: -0.34, 95% CI: -0.47 to -0.20; 3 RCTs, 179 participants, MD: -0.44, 95% CI: -0.68 to -0.21, respectively). Berberine was associated with decreasing total cholesterol (3 RCTs, 201 participants; MD: -0.44, 95% CI: -0.60 to -0.29), waist circumference (3 RCTs, 197 participants, MD: -2.74, 95% CI: -4.55 to -0.93), and waist-to-hip ratio (4 RCTs, 258 participants, MD: -0.04, 95% CI: -0.05 to -0.03) compared with metformin, but not with improved BMI (4 RCTs, 262 participants, MD: -0.03, 95% CI: -0.46 to 0.39). Berberine did not increase the incidence of gastrointestinal adverse events (3 RCTs, 567 participants, RR: 1.01, 95% CI: 0.76 to 1.35) or serious events during pregnancy (RR: 0.98, 95% CI: 0.70 to 1.37) compared with placebo.

Conclusion

This review found no solid evidence that berberine could improve live birth or other clinical outcomes in women with PCOS. However, berberine appeared to be more efficacious for improving insulin resistance and dyslipidemia and decreasing androgen levels and LH/FSH ratio in women with PCOS when compared with metformin.

Obesity, Neuroinflammation, and Reproductive Function

The increasing occurrence of obesity has become a significant public health concern. Individuals with obesity have higher prevalence of heart disease, stroke, osteoarthritis, diabetes, and reproductive disorders. Reproductive problems include menstrual irregularities, pregnancy complications, and infertility due to anovulation, in women, and lower testosterone and diminished sperm count, in men. In particular, women with obesity have reduced levels of both gonadotropin hormones, and, in obese men, lower testosterone is accompanied by diminished LH. Taken together, these findings indicate central dysregulation of the hypothalamic-pituitary-gonadal axis, specifically at the level of the GnRH neuron function, which is the final brain output for the regulation of reproduction. Obesity is a state of hyperinsulinemia, hyperlipidemia, hyperleptinemia, and chronic inflammation. Herein, we review recent advances in our understanding of how these metabolic and immune changes affect hypothalamic function and regulation of GnRH neurons. In the latter part, we focus on neuroinflammation as a major consequence of obesity and discuss findings that reveal that GnRH neurons are uniquely positioned to respond to inflammatory changes.

Gonadotrope androgen receptor mediates pituitary responsiveness to hormones and androgen-induced subfertility

Many women with hyperandrogenemia suffer from irregular menses and infertility. However, it is unknown whether androgens directly affect reproduction. Since animal models of hyperandrogenemia-induced infertility are associated with obesity, which may impact reproductive function, we have created a lean mouse model of elevated androgen using implantation of low dose dihydrotestosterone (DHT) pellets to separate the effects of elevated androgen from obesity. The hypothalamic-pituitary-gonadal axis controls reproduction. While we have demonstrated that androgen impairs ovarian function, androgen could also disrupt neuroendocrine function at the level of brain and/or pituitary to cause infertility. To understand how elevated androgens might act on pituitary gonadotropes to influence reproductive function, female mice with disruption of the androgen receptor (Ar) gene specifically in pituitary gonadotropes (PitARKO) were produced. DHT treated control mice with intact pituitary Ar (Con-DHT) exhibit disrupted estrous cyclicity and fertility with reduced pituitary responsiveness to GnRH at the level of both calcium signaling and LH secretion. These effects were ameliorated in DHT treated PitARKO mice. Calcium signaling controls GnRH regulation of LH vesicle exotocysis. Our data implicated upregulation of GEM (a voltage-dependent calcium channel inhibitor) in the pituitary as a potential mechanism for androgen's pathological effects. These results demonstrate that gonadotrope AR, as an extra-ovarian regulator, plays an important role in reproductive pathophysiology.

Association between duration of obesity and severity of ovarian dysfunction in rat-cafeteria diet approach

Consumption of unhealthy, energy-dense palatable food during early age leads to obesity in children and the onset of obesity during childhood has a profound effect on the reproductive health of women. In this study, the mechanism underlying diet-induced obesity on ovarian dysfunction was studied by exposing rats to cafeteria diet (CAFD) for two different durations. For that purpose, 21-day-old female Sprague Dawley rats were fed ad libitum with a standard diet (control group) and a cafeteria diet (CAFD group) for a period of 20 weeks (20 W) and 32 weeks (32 W). We observed obesity, hyperglycemia, hyperlipidemia, hyperleptinemia and hypoadiponectinemia in CAFD fed groups. Hyperinsulinemia, hypergonadotrophism, hypertestosteronemia and hyperprogesteronemia were observed in the 20 W-CAFD group. Conversely, in the 32 W-CAFD group hypersecretion declined to hyposecretion. The levels of estradiol remained low during both time periods. The duration of estrous cycle was extended in the CAFD fed rats. The ovary weight was higher in the 20 W-CAFD fed rats but it was drastically reduced over a longer duration cafeteria diet feeding. In the 20 W-CAFD fed rats, the protein levels of LHR, StAR, CYP11A1, 3β-HSD and 17β-HSD were increased but FSHR and CYP19A1 levels were decreased in the ovary. On the other hand, gonadotropin receptor and the protein levels of steroidogenic enzymes were decreased in the ovary of 32 W-CAFD fed rats. We conclude that the duration of energy-dense diet consumption has differential regulatory mechanism in altering the ovarian steroid production. In 20 W-CAFD fed rats, hypergonadotropic condition was observed whereas, 32 W-CAFD consumption induced hypogonadotropic hypogonadism.

PI3K signalling in leptin receptor cells: Role in growth and reproduction

Nutrition and growth are important signals for pubertal development, although how they are perceived and integrated in brain circuits has not been well defined. Growth hormones and metabolic cues both recruit phosphatidylinositol 3-kinase (PI3K) signalling in hypothalamic sites, although whether they converge into the same neuronal population(s) is also not known. In this review, we discuss recent findings from our laboratory showing the role of PI3K subunits in cells directly responsive to the adipocyte-derived hormone leptin in the coordination of growth, pubertal development and fertility. Mice with deletion of PI3K p110α and p110β catalytic subunits in leptin receptor cells (LR^Δα+β ) have a lean phenotype associated with increased energy expenditure, locomotor activity and thermogenesis. The LR^Δα+β mice also show deficient growth and delayed puberty. Deletion of a single subunit (ie, p110α) in LR cells (LR^Δα ) causes a similar phenotype of increased energy expenditure, deficient growth and delayed pubertal development, indicating that these functions are preferably controlled by p110α. The LR^Δα mice show enhanced leptin sensitivity in metabolic regulation but, remarkably, these mice are unresponsive to the effects of leptin on growth and puberty. PI3K is also recruited by insulin and a subpopulation of LR neurones is responsive to i.c.v. insulin administration. Deletion of insulin receptor in LR cells causes no changes in body weight or linear growth and induces only a mild delay in pubertal completion. Our findings demonstrate that PI3K in LR cells plays an essential role in growth and reproduction. We will also discuss the potential neural pathways underlying these effects.

Bitter Taste Receptor Ligand Improves Metabolic and Reproductive Functions in a Murine Model of PCOS

Polycystic ovary syndrome (PCOS) results from functional ovarian hyperandrogenism due to dysregulation of androgen secretion. Cultured theca cells from polycystic ovaries of women with the most common form of PCOS overexpress most androgen producing enzymes, particularly CYP450c17. In this study, a murine model was used of PCOS induced by chronic feeding with a high-fat diet that exhibits the reproductive, hyperandrogenic, and metabolic constellation of PCOS symptoms seen in women. Oral administration of KDT501, a hops-derived bitter taste receptor (Tas2R 108) isohumulone ligand resulted in resolution of PCOS-associated endocrine and metabolic disturbances and restored reproductive function. Pioglitazone, a PPARγ agonist, also improved metabolic and reproductive function, though not to the same degree as KDT501. Specifically, treatment of the murine PCOS model with KDT501 resulted in reduced testosterone and androstenedione levels in the absence of significant changes in LH or FSH, improved glucose tolerance and lipid metabolism, and reduced hepatic lipid infiltration and adiposity. There was significant improvement in estrous cyclicity and an increase in the number of ovarian corpora lutea, indicative of improved reproductive function after exposure to KDT501. Finally, ex vivo exposure of murine ovaries to KDT501 attenuated androgen production and ovarian expression of CYP450c17. Interestingly, the ovaries expressed Tas2R 108, suggesting a potential regulation of ovarian steroidogenesis through this chemosensory receptor family. In summary, a therapeutic strategy for PCOS possibly could include direct influences on ovarian steroidogenesis that are independent of gonadotrophic hormone regulation.

Chinese herbal decoction of Wenshen Yangxue formula improved fertility and pregnancy rate in mice through PI3K/Akt signaling

OBJECTIVE

Traditional Chinese medicine (TCM) is an effective management to infertility. The association between TCM-mediated fertility and inhibition of phosphatidylinositol-3-kinase (PI3K) would be investigated.

METHODS

Institute of Cancer Research mice were treated with three herbal decoctions, named Wenshen Yangxue formula, Wenshen formula, and Yangxue formula, plus with human gonadotropins. PI3K inhibitor wortmannin was administrated to half of mice. Some index such as body weight, fertility ability would be investigated. The expression of P13K/Akt signaling was detected by using Western blot analysis.

RESULTS

No difference was observed in body weight among groups. Mice receiving the administration of human gonadotropins and herbal decoctions showed increased follicle numbers, percentage of fertilization, and promoted embryonic development. The treatment of Wenshen Yangxue formula decoction showed the highest efficiency, significant higher than Wenshen and Yangxue formulas. And increased the expression of p-PI3K and p-Akt proteins.

CONCLUSION

These results suggested the herbal decoctions promoted the fertilization of mice, which was related to the charge of PI3K/Akt activation.

Dietary factors and serum antimüllerian hormone concentrations in late premenopausal women

OBJECTIVE

To study the associations between dietary factors and circulating antimüllerian hormone (AMH) concentrations among late premenopausal women.

DESIGN

AMH concentrations were measured in serum samples collected at enrollment from 296 women (aged 35-45 years) in the Sister Study cohort. Usual dietary intakes in the past 12 months were assessed using a validated food frequency questionnaire. Dietary exposures of interest included macronutrients, dietary fat subtypes, fiber, and glycemic index. Multivariable linear regression was used to evaluate associations between dietary variables and serum AMH concentrations. We also used nutrient density models to examine isocaloric replacement of macronutrients.

SETTING

Not applicable.

PATIENTS

Women aged 35-45 years.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Serum AMH concentrations in nanograms per milliliter (ng/mL).

RESULTS

AMH concentrations were positively associated with percentage of energy from carbohydrates (β per 5% calories = 0.141 [95% CI 0.023, 0.259]; P trend = .019), and inversely associated with percentage of energy from fat (β per 5% calories = -0.152 [95% CI -0.299, -0.004]; P trend = .044). In analyses of dietary fat subtypes, AMH decreased with increasing monounsaturated fatty acids (P trend = .082) and polyunsaturated fatty acids (P trend = .043), particularly ω-6 fatty acids (P trend = .044), whereas no strong trend was observed for saturated fatty acids. Protein and alcohol intake were not strongly associated with AMH.

CONCLUSIONS

Our cross-sectional analyses in a sample of late premenopausal women suggest that dietary fat intake may be inversely associated with circulating AMH concentrations. Further research in prospective studies is warranted to evaluate dietary factors as potential modifiers of ovarian reserve.

Impairments in the reproductive axis of female mice lacking estrogen receptor β in GnRH neurons

The effect of estrogen on the differentiation and maintenance of reproductive tissues is mediated by two nuclear estrogen receptors (ERs), ERα, and ERβ. Lack of functional ERα and ERβ genes in vivo significantly affects reproductive function; however, the target tissues and signaling pathways in the hypothalamus are not clearly defined. Here, we describe the generation and reproductive characterization of a complete-ERβ KO (CERβKO) and a GnRH neuron-specific ERβKO (GERβKO) mouse models. Both ERβKO mouse models displayed a delay in vaginal opening and first estrus. Hypothalamic gonadotropin-releasing hormone (GnRH) mRNA expression levels in both ERβKO mice were similar to control mice; however female CERβKO and GERβKO mice had lower basal and surge serum gonadotropin levels. Although a GnRH stimulation test in both female ERβKO models showed preserved gonadotropic function in the same animals, a kisspeptin stimulation test revealed an attenuated response by GnRH neurons, suggesting a role for ERβ in normal GnRH neuron function. No alteration in estrogen-negative feedback was observed in either ERβKO mouse models after ovariectomy and estrogen replacement. Further, abnormal development of ovarian follicles with low serum estradiol levels and impairment of fertility were observed in both ERβKO mouse models. In male ERβKO mice, no differences in the timing of pubertal onset or serum luteinizing hormone and follicle-stimulating hormone levels were observed as compared with controls. Taken together, these data provide in vivo evidence for a role of ERβ in GnRH neurons in modulating puberty and reproduction, specifically through kisspeptin responsiveness in the female hypothalamic-pituitary-gonadal axis.

Integration of Circadian and Metabolic Control of Reproductive Function

Optimal fertility in humans and animals relies on the availability of sufficient metabolic fuels, information about which is communicated to the brain via levels of the hormones leptin and insulin. The circadian clock system is also critical; this input is especially evident in the precise timing of the female-specific surge of GnRH and LH secretion that triggers ovulation the next day. Chronodisruption and metabolic imbalance can both impair reproductive activity, and these two disruptions exacerbate each other, such that they often occur simultaneously. Kisspeptin neurons located in the anteroventral periventricular nucleus of the hypothalamus are able to integrate both circadian and metabolic afferent inputs and use this information to modulate the timing and magnitude of the preovulatory GnRH/LH surge. In an environment in which exposure to high caloric diets and chronodisruptors such as artificial night lighting, shift work, and transmeridian travel have become the norm, the implications of these factors for couples struggling to conceive deserve closer attention and more public education.

The Processes of Anterior Pituitary Hormone Pulse Generation

More than 60 years ago, Geoffrey Harris described his "neurohumoral theory," in which the regulation of pituitary hormone secretion was a "simple" hierarchal relationship, with the hypothalamus as the controller. In models based on this theory, the electrical activity of hypothalamic neurons determines the release of hypophysiotropic hormones into the portal circulation, and the pituitary simply responds with secretion of a pulse of hormone into the bloodstream. The development of methodologies allowing the monitoring of the activities of members of the hypothalamic-vascular-pituitary unit is increasingly allowing dissection of the mechanisms generating hypothalamic and pituitary pulses. These have revealed that whereas hypothalamic input is required, its role as a driver of pulsatile pituitary hormone secretion varies between pituitary axes. The organization of pituitary cells has a key role in the modification of their response to hypophysiotropic factors that can lead to a memory of previous demand and enhanced function. Feedback can lead to oscillatory hormone output that is independent of pulses of hypophysiotropic factors and instead, results from the temporal relationship between pituitary output and target organ response. Thus, the mechanisms underlying the generation of pulses cannot be generalized, and the circularity of feedforward and feedback interactions must be considered to understand both normal physiological function and pathology. We describe some examples of the clinical implications of recognizing the importance of the pituitary and target organs in pulse generation and suggest avenues for future research in both the short and long term.

Diet-Induced Obesity Elicits Macrophage Infiltration and Reduction in Spine Density in the Hypothalami of Male but Not Female Mice

Increasing prevalence in obesity has become a significant public concern. C57BL/6J mice are prone to diet-induced obesity (DIO) when fed high-fat diet (HFD), and develop chronic inflammation and metabolic syndrome, making them a good model to analyze mechanisms whereby obesity elicits pathologies. DIO mice demonstrated profound sex differences in response to HFD with respect to inflammation and hypothalamic function. First, we determined that males are prone to DIO, while females are resistant. Ovariectomized females, on the other hand, are susceptible to DIO, implying protection by ovarian hormones. Males, but not females, exhibit changes in hypothalamic neuropeptide expression. Surprisingly, ovariectomized females remain resistant to neuroendocrine changes, showing that ovarian hormones are not necessary for protection. Second, obese mice exhibit sex differences in DIO-induced inflammation. Microglial activation and peripheral macrophage infiltration is seen in the hypothalami of males, while females are protected from the increase in inflammatory cytokines and do not exhibit microglia morphology changes nor monocyte-derived macrophage infiltration, regardless of the presence of ovarian hormones. Strikingly, the anti-inflammatory cytokine IL-10 is increased in the hypothalami of females but not males. Third, this study posits a potential mechanism of obesity-induced impairment of hypothalamic function whereby obese males exhibit reduced levels of synaptic proteins in the hypothalamus and fewer spines in GnRH neurons, located in the areas exhibiting macrophage infiltration. Our studies suggest that inflammation-induced synaptic remodeling is potentially responsible for hypothalamic impairment that may contribute to diminished levels of gonadotropin hormones, testosterone, and sperm numbers, which we observe and corresponds to the observations in obese humans. Taken together, our data implicate neuro-immune mechanisms underlying sex-specific differences in obesity-induced impairment of the hypothalamic function with potential consequences for reproduction and fertility.