High-Fat Diet Causes Subfertility and Compromised Ovarian Function Independent of Obesity in Mice

Ras/MAPK signaling mediates adipose tissue control of ovarian germline survival and ovulation in Drosophila melanogaster

From insects to humans, oogenesis is tightly linked to nutritional input, yet little is known about how whole organism physiology matches dietary changes with oocyte development. Considering that diet-induced adipose tissue dysfunction is associated with an increased risk for fertility problems, and other obesity-associated pathophysiologies, it is critical to decipher the cellular and molecular mechanisms linking adipose nutrient sensing to remote control of the ovary and other tissues. Our previous studies in Drosophila melanogaster have shown that amino acid sensing, via the amino acid response pathway and mTOR-mediated signaling function within adipocytes to control germline stem cell maintenance and ovulation, respectively. Additionally, we demonstrated that insulin/insulin-like growth factor signaling within adipocytes employs distinct effector axes, PI3K/Akt1-dependent and -independent, downstream of insulin receptor activity to mediate fat-to-ovary communication. Here, we report that the Ras/MAPK signaling axis functions in adipocytes to regulate early germline cyst survival and ovulation of mature oocytes but is not important for germline stem cell maintenance or the progression through vitellogenesis. Thus, these studies uncover the complexity of signaling pathway activity that mediates inter-organ communication.

Senolytic treatment fails to improve ovarian reserve or fertility in female mice

Senescent cell number increases with age in different tissues, leading to greater senescent cell load, proinflammatory stress, and tissue dysfunction. In the current study, we tested the efficacy of senolytic drugs to reduce ovarian senescence and improve fertility in reproductive age female mice. In the first experiment, 1-month-old C57BL/6 female mice were treated every other week with D + Q (n = 24) or placebo (n = 24). At 3 and 6 months of age, female mice were mated with untreated males to evaluate pregnancy rate and litter size. In the second experiment, 6-month-old C57BL/6 female mice were treated monthly with D + Q (n = 30), fisetin (n = 30), or placebo (n = 30). Females were treated once a month until 11 months of age, then they were mated with untreated males for 30 days to evaluate pregnancy rate and litter size. In the first experiment, D + Q treatment did not affect pregnancy rate (P = 0.68), litter size (P = 0.58), or ovarian reserve (P > 0.05). Lipofuscin staining was lower in females treated with D + Q (P = 0.04), but expression of senescence genes in ovaries was similar. In the second experiment, D + Q or fisetin treatment also did not affect pregnancy rate (P = 0.37), litter size (P = 0.20), or ovarian reserve (P > 0.05). Lipofuscin staining (P = 0.008) and macrophage infiltration (P = 0.002) was lower in fisetin treated females. Overall, treatment with D + Q or fisetin did not affect ovarian reserve or fertility but did decrease some senescence markers in the ovary.

Leptin signalling regulates transcriptional differences in granulosa cells from genetically obese mice but not the activation of NLRP3 inflammasome

Obesity is associated with increased ovarian inflammation and the establishment of leptin resistance. We presently investigated the role of impaired leptin signalling on transcriptional regulation in granulosa cells (GCs) collected from genetically obese mice. Furthermore, we characterised the association between ovarian leptin signalling, the activation of the NOD-like receptor protein 3 (NLRP3) inflammasome and macrophage infiltration in obese mice. After phenotype characterisation, ovaries were collected from distinct group of animals for protein and mRNA expression analysis: (i) mice subjected to a diet-induced obesity (DIO) protocol, where one group was fed a high-fat diet (HFD) and another a standard chow diet (CD) for durations of 4 or 16 weeks; (ii) mice genetically deficient in the long isoform of the leptin receptor (ObRb; db/db); (iii) mice genetically deficient in leptin (ob/ob); and (iv) mice rendered pharmacologically hyperleptinemic (LEPT). Next, GCs from antral follicles isolated from db/db and ob/ob mice were subjected to transcriptome analysis. Transcriptional analysis revealed opposing profiles in genes associated with steroidogenesis and prostaglandin action between the genetic models, despite the similarities in body weight. Furthermore, we observed no changes in the mRNA and protein levels of NLRP3 inflammasome components in the ovaries of db/db mice or in markers of M1 and M2 macrophage infiltration. This contrasted with the downregulation of NLRP3 inflammasome components and M1 markers in ob/ob and 16-wk HFD-fed mice. We concluded that leptin signalling regulates NLRP3 inflammasome activation and the expression of M1 markers in the ovaries of obese mice in an ObRb-dependent and ObRb-independent manner. Furthermore, we found no changes in the expression of leptin signalling and NLRP3 inflammasome genes in GCs from db/db and ob/ob mice, which was associated with no effects on macrophage infiltration genes, despite the dysregulation of genes associated with steroidogenesis in homozygous obese db/db. Our results suggest that: (i) the crosstalk between leptin signalling, NLRP3 inflammasome and macrophage infiltration takes place in ovarian components other than the GC compartment; and (ii) transcriptional changes in GCs from homozygous obese ob/ob mice suggest structural rearrangement and organisation, whereas in db/db mice the impairment in steroidogenesis and secretory activity.

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.

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.

Beneficial effects of metformin on mice female fertility after a high-fat diet intake

Female fertility is highly dependent on energy balance. High fat diet (HFD) intake entails a risk of infertility and ovulatory disorders. Considering the increase in the prevalence of overweight and obesity over the last decades, it is crucial to understand the mechanisms involved in overweight-associated infertility. In this study, we evaluated the reproductive performance of female mice fed with a HFD and the effects of metformin administration on ovarian function in these mice. We hypothesized that one of the mechanisms involved in subfertility due to a HFD intake is the alteration of ovarian blood vessel formation. We found that mice fed with HFD had altered estrous cycles and steroidogenesis, increased ovarian fibrosis, fewer pups per litter and require more time to achieve pregnancy. HFD-fed mice also presented dysregulated ovarian angiogenesis and an increase in nuclear DNA damage in ovarian cells. Ovulation rates were lower in these animals, as evidenced both in natural mating and after ovulation induction with gonadotropins. Metformin ameliorated ovarian angiogenesis, improved steroidogenesis, fibrosis, and ovulation, decreased the time to pregnancy and increased litter sizes in HFD-fed mice. We conclude that ovarian angiogenesis is one of the mechanisms detrimentally affected by HFD intake. Since metformin could improve ovarian microvasculature, it may be an interesting strategy to study in women to shed light on new targets for patients with metabolic disturbances.

Ovarian aging in humans: potential strategies for extending reproductive lifespan

Ovarian reserve is a term used to estimate the total number of immature follicles present in the ovaries. Between birth and menopause, there is a progressive decrease in the number of ovarian follicles. Ovarian aging is a continuous physiological phenomenon, with menopause being the clinical mark of the end of ovarian function. Genetics, measured as family history for age at the onset of menopause, is the main determinant. However, physical activity, diet, and lifestyle are important factors that can influence the age of menopause. The low estrogen levels after natural or premature menopause increased the risk for several diseases, resulting in increased mortality risk. Besides that, the decreasing ovarian reserve is associated to reduced fertility. In women with infertility undergoing in vitro fertilization, reduced markers of ovarian reserve, including antral follicular count and anti-Mullerian hormone, are the main indicators of reduced chances of becoming pregnant. Therefore, it becomes clear that the ovarian reserve has a central role in women's life, affecting fertility early in life and overall health later in life. Based on this, the ideal strategy for delaying ovarian aging should have the following characteristics: (1) be initiated in the presence of good ovarian reserve; (2) maintained for a long period; (3) have an action on the dynamics of primordial follicles, controlling the rate of activation and atresia; and (4) safe use in pre-conception, pregnancy, and lactation. In this review, we therefore discuss some of these strategies and its feasibility for preventing a decline in the ovarian reserve.

Protective effect of Salvia hispanica (chia seeds) against obesity induced ovarian disorders in rat model

The main goal of the current report is to assess the protective impacts of chia seeds against obesity-induced ovarian dysfunctions with a trial to elucidate the mechanism of action. Forty rats were divided into 4 groups including lean untreated, lean consuming chia seeds, obese untreated, and rats consumed high-fat diet (HFD) mixed with ground chia seeds for 10 weeks. Anthropometric measures including visceral fat, peri-ovarian fat, ovarian weights, and duration of the estrous cycle were computed. Serum luteinizing (LH), follicular stimulating (FSH), progesterone, estradiol hormones, and tumor necrosis-α (TNF-α) were estimated. Ovarian histopathology and immunohistochemistry (CD31) were performed. Results showed that chia seeds clearly reduced obesity and induced alteration in anthropometric measures with a clear increase in LH and progesterone. Such seeds notably reversed histopathological alteration and reduced TNF-α, and CD31 induced by HFD. Conclusively, chia seeds have a potential protective role against obesity-induced ovarian dysfunction owing to their anti-inflammatory properties.

The effect of dietary habits on oocyte/sperm quality

The effects of diet and nutritional habits on reproductive cells can be categorized in a variety of ways. In this review, the literature is divided, based on the dietary consumption effects on oocytes and sperm. Topics on dietary patterns and the intrauterine effect of maternal nutrition are covered. In general fruits, vegetables, whole greens, fish, legumes, and also dietary sources containing unsaturated fats can improve reproductive germ cell quality. In epidemiological studies, the food intake frequency questionnaire is one of the most common methods to assess diet. Due to methodological heterogeneity in dietary assessment and inadequacy in the measurement of dietary intake in the questionnaires used, several unreliable results may be reported. Thus, the quality of evidence needs to be improved, since nutritional diets may not be so simply objective and they are inadequate to explain obvious underlining mechanisms. In addition, various compounds that may be ingested can affect molecular mechanisms, influenced by other external factors (drugs, pesticides, smoking, alcohol) and changes in human nutritional parameters. Artificial Intelligence has recently gained widespread interest and may have a role in accurate analysis of dietary patterns for optimal nutritional benefit. Therefore, future prospective randomized studies and objective measurements, consisting of molecular level analysis of the impact on cells and clear-cut methods are needed for accurate assessment of the effect of dietary habits on reproductive treatment.

Multi-omics analysis reveals gut microbiota-ovary axis contributed to the follicular development difference between Meishan and Landrace × Yorkshire sows

BACKGROUND

The mechanism by which Meishan (MS) sows are superior to white crossbred sows in ovarian follicle development remains unclear. Given gut microbiota could regulate female ovarian function and reproductive capacity, this study aimed to determine the role of gut microbiota-ovary axis on follicular development in sows.

METHODS

We compared the ovarian follicular development, gut microbiota, plasma metabolome, and follicular fluid metabolome between MS and Landrace × Yorkshire (L × Y) sows. A H₂O₂-induced cell apoptosis model was used to evaluate the effects of multi-omics identified metabolites on the apoptosis of porcine ovarian granulosa cells in vitro.

RESULTS

Compared with L × Y sows, MS sows have greater ovary weight and improved follicular development, including the greater counts of large follicles of diameter ≥ 5 mm, secondary follicles, and antral follicles, but lesser atretic follicles. The ovarian granulosa cells in MS sows had alleviated apoptosis, which was indicated by the increased BCL-2, decreased caspases-3, and decreased cleaved caspases-3 than in L × Y sows. The ovarian follicular fluid of MS sows had higher concentrations of estradiol, progesterone, follicle-stimulating hormone, luteinizing hormone, and insulin like growth factor 1 than L × Y sows. Gut microbiota of MS sows formed a distinct cluster and had improved alpha diversity, including increased Shannon and decreased Simpson than those of L × Y sows. Corresponding to the enhanced function of carbohydrate metabolism and elevated short-chain fatty acids (SCFAs) in feces, the differential metabolites in plasma between MS and L × Y sows are also mainly enriched in pathways of fatty acid metabolism. There were significant correlations among SCFAs with follicular development, ovarian granulosa cells apoptosis, and follicular fluid hormones, respectively. Noteworthily, compared with L × Y sows, MS sows had higher follicular fluid SCFAs concentrations which could ameliorate H₂O₂-induced porcine granulosa cells apoptosis in vitro.

CONCLUSION

MS sows have more secondary and antral follicles, but fewer atretic follicles and apoptotic ovarian granulosa cells, as well as harbored a distinctive gut microbiota than L × Y sows. Gut microbiota may participate in regulating ovarian follicular development via SCFAs affecting granulosa cells apoptosis in sows.

Rerouting of follicle-stimulating hormone secretion and gonadal function

Follicle-stimulating hormone (FSH) and luteinizing hormone (LH) are synthesized in the same pituitary cell, i.e., gonadotrope. They both consist of a common α-subunit that is noncovalently assembled with a hormone-specific β-subunit in gonadotropes. The heterodimers exit gonadotropes through distinct modes of trafficking and secretion. The FSH is constitutively secreted, whereas LH is secreted in pulses through the regulated pathway that involves dense core granules. Based on several in vitro mutagenesis studies, the carboxy terminus heptapeptide of human LH-β subunit is identified as a gonadotrope sorting determinant. When heptapeptide is genetically fused to human FSH-β subunit and the mutant transgene expressed on a Fshb null genetic background, the rerouted FSH mutant dimer enters the LH secretory pathway, stored in dense core granules, coreleased with LH on gonadotropin releasing hormone stimulation and rescues Fshb null mice as efficiently as the constitutively secreted wild-type FSH. The rerouted FSH markedly suppresses follicle atresia and significantly enhances ovulations per cycle and prolongs the female reproductive life span. Gonadotropin rerouting is emerging as a novel paradigm to treat ovarian dysfunction in women, and may explain the origins of ovarian cyclicity as well as provide clues to understand gene and protein networks that maintain optimal ovarian function throughout the female reproductive life span.

A High-Fat and High-Carbohydrate Diet Promotes Reminiscent Hallmarks of an Aging Ovary in the Rabbit Model

The primary definition of ovarian aging refers to the loss of follicles. Moreover, the aging of the microenvironment in ovaries, specifically affecting the follicles, may reveal deterioration with advancing age. Besides aging, metabolic disorders associated with hypercaloric diets may affect ovarian health and manifest characteristics associated with premature aging. In this study, we used 10-week-old chinchilla rabbits fed with a high-fat and high-carbohydrate diet (HFCD) until 25 weeks of age to explore hallmarks of reminiscent ovarian aging. The HFCD diet appeared to affect the ovarian reserve, reflected in a significant decrease in primordial follicles. Likewise, Sudan black stain detection revealed substantial differences in the deposits of lipofuscin in the interstitial glands of HFCD-fed rabbits compared to controls, constituting a "hallmark" of aging. The HFCD showed no induced changes in the expression of SOD 2 in the interstitial gland; however, surface epithelium cells were greater expressed. Besides this, the HFCD induced nuclear translocation of NF-ΚΒ p65 factor transcription in surface epithelium cells. We conclude that an HFCD induces a greater accumulation of senescence cells in the interstitial gland, promoting characteristics reminiscent of ovarian aging. However, the activation mechanism of NF-KB caused by an HFCD, which may be stress-responsive and generated by the interstitial gland, requires further study.

High-fat diet causes mechanical allodynia in the absence of injury or diabetic pathology

Understanding the interactions between diet, obesity, and diabetes is important to tease out mechanisms in painful pathology. Western diet is rich in fats, producing high amounts of circulating bioactive metabolites. However, no research has assessed how a high-fat diet (HFD) alone may sensitize an individual to non-painful stimuli in the absence of obesity or diabetic pathology. To investigate this, we tested the ability of a HFD to stimulate diet-induced hyperalgesic priming, or diet sensitization in male and female mice. Our results revealed that 8 weeks of HFD did not alter baseline pain sensitivity, but both male and female HFD-fed animals exhibited robust mechanical allodynia when exposed to a subthreshold dose of intraplantar Prostaglandin E₂ (PGE₂) compared to mice on chow diet. Furthermore, calcium imaging in isolated primary sensory neurons of both sexes revealed HFD induced an increased percentage of capsaicin-responsive neurons compared to their chow counterparts. Immunohistochemistry (IHC) showed a HFD-induced upregulation of ATF3, a neuronal marker of injury, in lumbar dorsal root ganglia (DRG). This suggests that a HFD induces allodynia in the absence of a pre-existing condition or injury via dietary components. With this new understanding of how a HFD can contribute to the onset of pain, we can understand the dissociation behind the comorbidities associated with obesity and diabetes to develop pharmacological interventions to treat them more efficiently.

A Systematic Review of the Effects of High-Fat Diet Exposure on Oocyte and Follicular Quality: A Molecular Point of View

Worldwide, infertility affects between 10 and 15% of reproductive-aged couples. Female infertility represents an increasing health issue, principally in developing countries, as the current inclinations of delaying pregnancy beyond 35 years of age significantly decrease fertility rates. Female infertility, commonly imputable to ovulation disorders, can be influenced by several factors, including congenital malformations, hormonal dysfunction, and individual lifestyle choices, such as smoking cigarettes, stress, drug use and physical activity. Moreover, diet-related elements play an important role in the regulation of ovulation. Modern types of diet that encourage a high fat intake exert a particularly negative effect on ovulation, affecting the safety of gametes and the implantation of a healthy embryo. Identifying and understanding the cellular and molecular mechanisms responsible for diet-associated infertility might help clarify the confounding multifaceted elements of infertility and uncover novel, potentially curative treatments. In this view, this systematic revision of literature will summarize the current body of knowledge of the potential effect of high-fat diet (HFD) exposure on oocyte and follicular quality and consequent female reproductive function, with particular reference to molecular mechanisms and pathways. Inflammation, oxidative stress, gene expression and epigenetics represent the main mechanisms associated with mammal folliculogenesis and oogenesis.

Acupuncture for Female Infertility: Discussion on Action Mechanism and Application

A higher incidence of female infertility has been reported with an unexpectedly early appearance in recent years. The female infertility treatment and application of assisted reproductive technology have recently gained immense interest from scientists. Many studies have discussed the beneficial effects of acupuncture on female infertility. With advancements in science and medical technology, acupuncture-related research has increased in investigating its effectiveness in treating female infertility. This review focuses on a compilation of research in recent years on acupuncture for female infertility treatment and the exploration of the underlying mechanism. For this purpose, literature was searched using various search engines like PubMed, Web of Science, and Google Scholar. The search was refined by only focusing on recent studies on acupuncture effectiveness and mechanism in female infertility and evaluating pregnancy outcomes.

Overweight and Fertility: What We Can Learn from an Intergenerational Mouse Obesity Model

The aim of this study was to evaluate the effects of being overweight on the ability to conceive, fertilization rate, and in vivo development of embryos in regularly cycling, spontaneously ovulating, and naturally mated female mice. The study was based on statistical analysis of data collected during 14 experiments with identical design, performed on 319 control and 327 obese mice, developed in an intergenerational model of obesity induction which eliminates the impact of aging and high-fat feeding. Six-week-old mice with a vaginal sperm plug were slaughtered on embryonic days 2, 3, or 4, and the flushed contents of the oviducts and uteri were assessed by stereomicroscopy. The results showed no association between being overweight and the proportion of ovulating or fertilized females. On the other hand, a strong association was found between being overweight and ovulation yield. On embryonic day 2, significantly higher numbers of eggs were recovered from the oviducts of fertilized obese mice. Maternal overweight status was also associated with higher developmental capacities of preimplantation embryos. In conclusion, contrary to studies based on the high-fat-diet model, in female mice fed regular chow, being overweight was associated with an increased ovulation quota and higher developmental rate of fertilized oocytes. Being overweight did not impact ability to conceive. On the other hand, as documented in our previous studies, the quality of oocytes and blastocysts recovered from overweight mice developed in an intergenerational model of obesity was low.

Oocyte Quiescence: From Formation to Awakening

Decades of work using various model organisms have resulted in an exciting and emerging field of oocyte maturation. High levels of insulin and active mammalian target of rapamycin signals, indicative of a good nutritional environment, and hormones such as gonadotrophin, indicative of the growth of the organism, work together to control oocyte maturation to ensure that reproduction happens at the right timing under the right conditions. In the wild, animals often face serious challenges to maintain oocyte quiescence under long-term unfavorable conditions in the absence of mates or food. Failure to maintain oocyte quiescence will result in activation of oocytes at the wrong time and thus lead to exhaustion of the oocyte pool and sterility of the organism. In this review, we discuss the shared mechanisms in oocyte quiescence and awakening and a conserved role of noradrenergic signals in maintenance of the quiescent oocyte pool under unfavorable conditions in simple model organisms.

Intestinal Flora Changes Induced by a High-Fat Diet Promote Activation of Primordial Follicles through Macrophage Infiltration and Inflammatory Factor Secretion in Mouse Ovaries

Obesity induced by a high-fat diet (HFD) leads to the excessive consumption of primordial follicles (PFs) in the ovaries. There is systemic chronic inflammation under HFD conditions, but no previous studies have explored whether there is a certain causal relationship between HFD-induced chronic inflammation and the overactivation of PFs. Here, we showed that HFD causes disorders of intestinal microflora in mice, with five Gram-negative bacteria showing the most profound increase at the genus level compared to the normal diet (ND) groups and contributes to the production of endotoxin. Endotoxin promotes M1 macrophage infiltration in the ovaries, where they exhibit proinflammatory actions by secreting cytokines IL-6, IL-8, and TNFα. These cytokines then boost the activation of PFs by activating Signal Transducer and Activator of Transcription 3 (STAT3) signaling in follicles. Interestingly, transplantation of the HFD intestinal microflora to the ND mice partly replicates ovarian macrophage infiltration, proinflammation, and the overactivation of PFs. Conversely, transplanting the ND fecal microbiota to the HFD mice can alleviate ovarian inflammation and rescue the excessive consumption of PFs. Our findings uncover a novel and critical function of gut microbes in the process of PF overactivation under HFD conditions, and may provide a new theoretical basis for the microbial treatment of patients with premature ovarian insufficiency caused by HFD.

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.

Obesity modulates cell-cell interactions during ovarian folliculogenesis

Obesity is known to affect female reproduction, as evidenced by obese patients suffering from subfertility and abnormal oogenesis. However, the underlying mechanisms by which obesity impairs folliculogenesis are poorly documented. Here, we performed comprehensive single-cell transcriptome analysis in both regular diet (RD) and obese mouse models to systematically uncover how obesity affects ovarian follicle cells and their interactions. We found an increased proportion of Inhbb highly expressed granulosa cells (GCs) among all the GC subpopulations in obese mice. Under obese conditions, excessive androgen secreted from endocrine theca cells (ETCs) may contribute to the imbalanced change of GC subtypes through ETCs-GCs interactions. This is alleviated by enzalutamide, an androgen receptor antagonist. We also identified and confirmed typical GC markers, such as Marcks and Prkar2b, for sensitive evaluation of female fertility in obesity. These data represent a resource for studying transcriptional networks and cell-cell interactions during folliculogenesis under physiological and pathological conditions.

Obesity and oocyte quality: Significant implications for ART and Emerging mechanistic insights

The prevalence of obesity in adults worldwide, and specifically in women of reproductive age, is concerning given the risks to fertility posed by the increased risk of type 2 diabetes, metabolic syndrome and other non-communicable diseases. Obesity has a multi-systemic impact in female physiology that is characterized by the presence of oxidative stress, lipotoxicity, and the activation of pro-inflammatory pathways, inducing tissue-specific insulin resistance and ultimately conducive to abnormal ovarian function. A higher body mass is linked to Polycystic Ovary Syndrome, dysregulated menstrual cycles, anovulation, and longer time to pregnancy, even in ovulatory women. In the context of ART, compared to women of normal BMI, obese women have worse outcomes in every step of their journey, resulting in reduced success measured as live birth rate. Even after pregnancy is achieved, obese women have a higher chance of miscarriage, gestational diabetes, pregnancy complications, birth defects, and most worryingly, a higher risk of stillbirth and neonatal death. The potential for compounding effects of ART on pregnancy complications and infant morbidities in obese women has not been studied. There is still much debate in the field on whether these poorer outcomes are mainly driven by defects in oocyte quality, abnormal embryo development or an unaccommodating uterine environment, however the clinical evidence to date suggests a combination of all three are responsible. Animal models of maternal obesity shed light on the mechanisms underlaying the effects of obesity on the peri-conception environment, with recent findings pointing to lipotoxicity in the ovarian environment as a key driver of defects in oocytes that have not only reduced developmental competence but long-lasting effects in offspring health.

Diet normalization or caloric restriction as a preconception care strategy to improve metabolic health and oocyte quality in obese outbred mice

BACKGROUND

Maternal metabolic disorders are linked to reduced metabolic health and oocyte quality. Obese women are advised to lose weight before conception to increase pregnancy chances. However, as human studies show no univocal guidelines, more research is necessary to provide fundamental insights in the consequences of dietary weight loss on oocyte quality. Therefore, we investigated the impact of diet normalization or calorie restricted diet for two, four or six weeks, as preconception care intervention (PCCI), in obese mice on metabolic health and oocyte quality.

METHODS

Outbred female mice were fed a control (CTRL) or high-fat (HF) diet for 7 weeks (7w). Afterwards, HF-mice were put on different PCCIs, resulting in four treatment groups: 1) control diet up to 13w, 2) HF diet up to 13w (HF_HF), switch from a HF (7w) to 3) an ad libitum control diet (HF_CTRL) or 4) 30% calorie restricted control diet (HF_CR) for two, four or six weeks. Body weight, metabolic health, oocyte quality and overall fertility results were assessed.

RESULTS

Negative effects of HF diet on metabolic health, oocyte quality and pregnancy rates were confirmed. HF_CTRL mice progressively improved insulin sensitivity, glucose tolerance, serum insulin and cholesterol from PCCI w2 to w4. No further improvements in metabolic health were present at PCCI w6. However, PCCI w6 showed best oocyte quality improvements. Mature oocytes still showed elevated lipid droplet volume and mitochondrial activity but a significant reduction in ROS levels and ROS: active mitochondria ratio compared with HF_HF mice. HF_CR mice restored overall insulin sensitivity and glucose tolerance by PCCI w4. However, serum insulin, cholesterol and ALT remained abnormal. At PCCI w6, glucose tolerance was again reduced. However, only at PCCI w6, oocytes displayed reduced ROS levels and restored mitochondrial activity compared with HF_HF mice. In addition, at PCCI w6, both PCCI groups showed decreased mitochondrial ultrastructural abnormalities compared with the HF_HF group and restored pregnancy rates.

CONCLUSIONS

Diet normalization for 4 weeks showed to be the shortest, most promising intervention to improve metabolic health. Most promising improvements in oocyte quality were seen after 6 weeks of intervention in both PCCI groups. This research provides fundamental insights to be considered in developing substantiated preconception guidelines for obese women planning for pregnancy.

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.

Dyslipidemia Is Negatively Associated With the Cumulative Live-Birth Rate in Patients Without PCOS Following IVF/ICSI

Objective: To evaluate the effect of dyslipidemia on the cumulative live-birth rate (cLBR) in patients without polycystic ovary syndrome (PCOS) undergoing in vitro fertilization/intracytoplasmic sperm injection-embryo transfer (IVF/ICSI-ET) cycles. Methods: A total of 1,132 patients from the Yantai Yuhuangding Hospital Affiliated to Qingdao University from January 2016 to December 2017 were retrospectively included. The subjects were distributed into two groups based on their lipid profiles, namely, dyslipidemia group (n = 195) and control group (n = 937). The clinical and laboratory parameters of the two groups were analyzed, and a multivariate logistic regression analysis of the cLBR was conducted. In addition, subgroup analysis was carried out to avoid deviation according to the body mass index (BMI). Results: Patients with dyslipidemia had significantly greater BMI and longer duration of infertility, as well as lower antral follicle count and basal follicle-stimulating hormone level compared with patients without dyslipidemia. Stratified analysis showed that dyslipidemia was associated with a significantly higher total gonadotrophin dosage required for ovarian stimulation as well as lower number of oocytes retrieved, independent of obesity. The live-birth rate in fresh cycle and cLBR were higher in the control group, although the difference between the groups was not significant (54.9% vs. 47.3%, p = 0.116; 67.6% vs. 62.1%, p = 0.138). However, multivariate logistic regression analysis adjusting for potential confounders showed that dyslipidemia was negatively associated with cLBR (OR, 0.702, 95% CI, 0.533-0.881, p = 0.044). Conclusion: Our findings demonstrate for the first time that dyslipidemia has a deleterious impact on cLBR, independent of obesity, in non-PCOS population considered to have good prognosis. Assessment of serum lipid profiles as well as the provision of nutritional counseling is essential for increasing successful outcomes in assisted reproductive techniques.

Intergenerational high-fat diet impairs ovarian follicular development in rodents: a systematic review and meta-analysis

CONTEXT

Excessive consumption of high-fat diets has increased in the population over time and is harmful to female fertility.

OBJECTIVE

To investigate and discuss the effects of a high-fat diet on ovarian follicles in rodents.

DATA SOURCE

A systematic literature search of PubMed, EMBASE, Web of Science, and SCOPUS was carried out.

DATA EXTRACTION

Study characteristics, including study design, population, intervention, outcome, and risk of bias were analyzed.

DATA ANALYSIS

Twenty-two articles were included in a systematic review. Given the availability of studies, a quantitative meta-analysis included 12 studies that were performed for outcomes. There was a decrease in primordial follicles in female rodents that received a high-fat diet compared with the standard diet group. The offspring of mothers exposed to a high-fat diet showed an increased number of cystic follicles and a decreased number of secondary follicles and antral follicles, compared with the control diet group. Therefore, these high-fat diet-induced follicular alterations might impair the fertility of dams and their female newborns.

CONCLUSION

The consumption of a high-fat diet causes damage to ovarian follicular development, and this commitment will persist in the next generation.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO registration no. CRD42019133865.

A review on the relationship between anti-mullerian hormone and fertility in treating young breast cancer patients

Despite the fact that the long-term survival rate of breast cancer patients had been significantly improved owing to the systemic breast cancer therapies, there are still some side effects such as amenorrhea and fertility retention to be resolved, leaving it an important thing to understand the possible side effects on fertility and fertility preservation strategies while undergoing breast cancer treatment, due to the fact that most young patients hope to become pregnant and have children after breast cancer treatment. With anti-müllerian hormone (AMH) being the most sensitive marker for predicting ovarian function in young premenopausal women with breast cancer, this review is aimed to provide the additional guidance for clinical application of AMH by exploring the impacts of AMH on the fertility of young breast cancer patients, the relationship between AMH and metabolism, and the relationship between BRAC gene mutation and fertility protection strategies.

Effect of diet-induced obesity on kisspeptin-neurokinin B-dynorphin A neurons in the arcuate nucleus and luteinizing hormone secretion in sex hormone-primed male and female rats

Metabolic stress resulting from either lack or excess of nutrients often causes infertility in both sexes. Kisspeptin-neurokinin B-dynorphin A (KNDy) neurons in the arcuate nucleus (ARC) has been suggested to be a key players in reproduction via direct stimulation of the pulsatile gonadotropin-releasing hormone (GnRH) and subsequent gonadotropin release in mammalian species. In this study, we investigated the effect of high-fat diet (HFD) on hypothalamic KNDy gene expression to examine the pathogenic mechanism underlying obesity-induced infertility in male and female rats. Male and female rats at 7 weeks of age were fed with either a standard or HFD for 4 months. In the male rats, the HFD caused a significant suppression of ARC Kiss1 and Pdyn gene expressions, but did not affect the plasma luteinizing hormone (LH) levels and sizes of the morphology of the testis and epididymis. In the female rats, 58% of the HFD-fed female rats exhibited irregular estrous cycles, whereas the remaining rats showed regular cycles. Two of the 10 rats that showed HFD-induced irregular estrous cycles showed profound suppression of LH pulse frequency and the number of ARC Kiss1-expressing cells, whereas the other females showed normal LH pulses and ARC Kiss1 expression. Our finding shows that suppression of ARC Kiss1 expression might be the initial pathological change of hypogonadotropic hypogonadism in HFD-fed male rats, while the obese-related infertility in the female rats may be mainly induced by KNDy-independent pathways. Taken together, ARC kisspeptin neurons in male rats may be susceptible to HFD-induced obesity compared with those in female rats.

Moxibustion Ameliorates Ovarian Reserve in Rats by Mediating Nrf2/HO-1/NLRP3 Anti-Inflammatory Pathway

Diminished ovarian reserve (DOR) is an increasingly emerging reproductive disorder that disturbs reproductive-aged women, which is closely linked with inflammation. In clinic, moxibustion has already been applied for reproductive problems. In the present study, we examined the involvement of inflammation in DOR and investigated the effect of moxibustion for its anti-inflammatory activities. Methods. DOR rat model was established using tripterygium glycosides A tablets (TGs) suspension by intragastric administration and was then treated with either moxibustion or hormone replacement therapy (HRT), respectively. Estrus cycles were observed through vaginal cytology. Ovarian morphological alterations were observed by HE staining. The serum levels of follicle-stimulating hormone (FSH), estradiol (E₂), anti-Müllerian hormone (AMH), tumor necrosis factor alpha (TNF-α), and interleukin-10 (IL-10) were measured through ELISA. The expression levels of Nrf2, HO-1, and NLRP3 were detected using immunohistochemistry. Nrf2, HO-1, and NLRP3 mRNA were examined by RT-PCR. Results. Moxibustion improved estrus cycles, FSH, E₂, and AMH levels relative to DOR rats as well as HRT, while also inhibiting ovarian tissue injury. Anti-inflammatory cytokine IL-10 in peripheral blood was upregulated, and proinflammatory factor TNF-α was decreased after treatment with moxibustion. Moxibustion enhanced the expression of mRNA and protein of nuclear factor erythroid 2-related factor (Nrf2) and heme oxygenase-1 (HO-1); in the mean time, nucleotide-binding oligomerization domain-like receptor protein 3 (NLRP3) was suppressed. Conclusions. We demonstrated that moxibustion could ameliorate the ovarian reserve in rats induced by TGs. Overall, the effect of moxibustion was comparable to that of HRT. The underlying mechanism could be attributed to the anti-inflammatory effects of moxibustion, which suppressed NLRP3 activation by upregulating Nrf2/HO-1 signaling pathway.

Growth hormone increases DNA damage in ovarian follicles and macrophage infiltration in the ovaries

Evidence points to an important role of the growth hormone (GH) in the aging process and longevity. GH-deficient mice are smaller, live longer than normal littermates, and females have an increased ovarian reserve. The aim of the study was to evaluate the role of GH in the ovarian reserve by evaluating DNA damage, macrophage infiltration, and granulosa cell number in primordial and primary follicles. Experiment 1 used GH-deficient Ames dwarf mice (df/df, n = 12) and their normal littermates (N/df, n = 12), receiving GH or saline injections. Experiment 2 included transgenic mice overexpressing bovine GH (bGH) (n = 6) and normal mice (N, n = 6). DNA damage (anti-γH2AX) and macrophage counting (anti-CD68) were evaluated by immunofluorescence. Female df/df mice had lower γH2AX foci intensity in both oocytes and granulosa cells of primordial and primary follicles (p < 0.05), indicating fewer DNA double-strand breaks (DSBs). GH treatment increased DSBs in both df/df and N/df mice. Inversely, bGH mice had a higher quantity of DSBs in both oocytes and granulosa cells of primordial and primary follicles (p < 0.05). Df/df mice showed ovarian tissue with less macrophage infiltration than N/df mice (p < 0.05) and GH treatment increased macrophage infiltration (p < 0.05). In contrast, bGH mice had ovarian tissue with more macrophage infiltration compared to normal mice (p < 0.05). The current study shows that GH increases DNA DSBs in oocytes and granulosa cells and raises macrophage infiltration in the ovaries, pointing to the role of the GH/IGF-I axis in maintenance of oocyte DNA integrity and ovarian macrophage infiltration in mice.

Revisiting the Impact of Local Leptin Signaling in Folliculogenesis and Oocyte Maturation in Obese Mothers

The complex nature of folliculogenesis regulation accounts for its susceptibility to maternal physiological fitness. In obese mothers, progressive expansion of adipose tissue culminates with severe hyperestrogenism and hyperleptinemia with detrimental effects for ovarian performance. Indeed, maternal obesity is associated with the establishment of ovarian leptin resistance. This review summarizes current knowledge on potential effects of impaired leptin signaling throughout folliculogenesis and oocyte developmental competence in mice and women.

Ovarian follicles are resistant to monocyte perturbations-implications for ovarian health with immune disruption†

Monocytes and macrophages are the most abundant immune cell populations in the adult ovary, with well-known roles in ovulation and corpus luteum formation and regression. They are activated and proliferate in response to immune challenge and are suppressed by anti-inflammatory treatments. It is also likely they have a functional role in the healthy ovary in supporting the maturing follicle from the primordial through to the later stages; however, this role has been unexplored until now. Here, we utilized a Cx3cr1-Dtr transgenic Wistar rat model that allows a conditional depletion of circulating monocytes, to investigate their role in ovarian follicle health. Our findings show that circulating monocyte depletion leads to a significant depletion of ovarian monocytes and monocyte-derived macrophages. Depletion of monocytes was associated with a transient reduction in circulating anti-Müllerian hormone (AMH) at 5 days postdepletion. However, the 50-60% ovarian monocyte/macrophage depletion had no effect on ovarian follicle numbers, follicle atresia, or apoptosis, within 5-21 days postdepletion. These data reveal that the healthy adult ovary is remarkably resistant to perturbations of circulating and ovarian monocytes despite acute changes in AMH. These data suggest that short-term anti-inflammatory therapies that transiently impact on circulating monocytes are unlikely to disrupt ovarian follicle health, findings that have significant implications for fertility planning relative to the experience of an immune challenge or immunosuppression.

Short-term Western-style diet negatively impacts reproductive outcomes in primates

A maternal Western-style diet (WSD) is associated with poor reproductive outcomes, but whether this is from the diet itself or underlying metabolic dysfunction is unknown. Here, we performed a longitudinal study using regularly cycling female rhesus macaques (n = 10) that underwent 2 consecutive in vitro fertilization (IVF) cycles, one while consuming a low-fat diet and another 6–8 months after consuming a high-fat WSD. Metabolic data were collected from the females prior to each IVF cycle. Follicular fluid (FF) and oocytes were assessed for cytokine/steroid levels and IVF potential, respectively. Although transition to a WSD led to weight gain and increased body fat, no difference in insulin levels was observed. A significant decrease in IL-1RA concentration and the ratio of cortisol/cortisone was detected in FF after WSD intake. Despite an increased probability of isolating mature oocytes, a 44% reduction in blastocyst number was observed with WSD consumption, and time-lapse imaging revealed delayed mitotic timing and multipolar divisions. RNA sequencing of blastocysts demonstrated dysregulation of genes involved in RNA binding, protein channel activity, mitochondrial function and pluripotency versus cell differentiation after WSD consumption. Thus, short-term WSD consumption promotes a proinflammatory intrafollicular microenvironment that is associated with impaired preimplantation development in the absence of large-scale metabolic changes.

Chronic Inflammation in PCOS: The Potential Benefits of Specialized Pro-Resolving Lipid Mediators (SPMs) in the Improvement of the Resolutive Response

PCOS as the most common endocrine disorder of women in their reproductive age affects between 5–15% of the female population. Apart from its cardinal symptoms, like irregular and anovulatory cycles, hyperandrogenemia and a typical ultrasound feature of the ovary, obesity, and insulin resistance are often associated with the disease. Furthermore, PCOS represents a status of chronic inflammation with permanently elevated levels of inflammatory markers including IL-6 and IL-18, TNF-α, and CRP. Inflammation, as discovered only recently, consists of two processes occurring concomitantly: active initiation, involving “classical” mediators including prostaglandins and leukotrienes, and active resolution processes based on the action of so-called specialized pro-resolving mediators (SPMs). These novel lipid mediator molecules derive from the essential ω3-poly-unsaturated fatty acids (PUFAs) DHA and EPA and are synthesized via specific intermediates. The role and benefits of SPMs in chronic inflammatory diseases like obesity, atherosclerosis, and Diabetes mellitus has become a subject of intense research during the last years and since PCOS features several of these pathologies, this review aims at summarizing potential roles of SPMs in this disease and their putative use as novel therapeutics.

Calorie restriction during gestation affects ovarian reserve in offspring in the mouse

The aim of this study was to investigate the effect of calorie restriction (CR) during pregnancy in mice on metabolism and ovarian function in the offspring. Pregnant female mice were divided into two groups, a control group and a CR group (n=7 in each). Mice in the CR group were fed 50% of the amount consumed by control females from Day 10 of gestation until delivery. After weaning, the offspring received diet ad libitum until 3 months of age, when ovaries were collected. Ovaries were serially cut and every sixth section was used for follicle counting. Female offspring from CR dams tended to have increased bodyweight compared with offspring from control females (P=0.08). Interestingly, fewer primordial follicles (60% reduction; P=0.001), transitional follicles (P=0.0006) and total follicles (P=0.006) were observed in offspring from CR mothers. The number of primary, secondary and tertiary follicles did not differ between the groups (P>0.05). The CR offspring had fewer DNA double-strand breaks in primary follicle oocytes (P=0.03). In summary, CR during the second half of gestation decreased primordial ovarian follicle reserve in female offspring. These findings suggest that undernutrition during the second half of gestation may decrease the reproductive lifespan of female offspring.

Dietary Supplementation of Lauric Acid Alleviates the Irregular Estrous Cycle and the Impaired Metabolism and Thermogenesis in Female Mice Fed with High-Fat Diet (HFD)

Lauric acid (LA) has been implicated in the prevention/treatment of obesity. However, the role of LA in modulating an obesity-related female reproductive disorder remains largely unknown. Here, female mice were fed a control diet, high-fat diet (HFD), or HFD supplemented with 1% LA. The results demonstrated that the HFD-induced estrous cycle irregularity and the reduction of serum follicle-stimulating hormone (FSH) were alleviated by LA supplementation. In possible mechanisms, LA supplementation led to significant increase in serum lipid metabolites such as sphingomyelin and lysophosphatidylcholine containing LA (C12:0) and the improvement of glucose metabolism in mice fed HFD. Moreover, impaired body energy metabolism and weakened brown adipose tissue (BAT) thermogenesis of HFD-fed mice were improved by LA supplementation. Together, these findings showed that LA supplementation alleviated HFD-induced estrous cycle irregularity, possibly associated with altered serum lipid metabolites, improved glucose metabolism, body energy metabolism, and BAT thermogenesis. These findings suggested the potential application of LA in alleviating obesity and its related reproductive disorders.

The Interconnections Between Somatic and Ovarian Aging in Murine Models

The mammalian female is born with a limited ovarian reserve of primordial follicles. These primordial follicles are slowly activated throughout the reproductive lifecycle, thereby determining lifecycle length. Once primordial follicles are exhausted, women undergo menopause, which is associated with several metabolic perturbations and a higher mortality risk. Long before exhaustion of the reserve, females experience severe declines in fertility and health. As such, significant efforts have been made to unravel the mechanisms that promote ovarian aging and insufficiency. In this review, we explain how long-living murine models can provide insights in the regulation of ovarian aging. There is now overwhelming evidence that most life-span-extending strategies, and long-living mutant models simultaneously delay ovarian aging. Therefore, it appears that the same mechanisms that regulate somatic aging may also be modulating ovarian aging and germ cell exhaustion. We explore several potential contributing mechanisms including insulin resistance, inflammation, and DNA damage-all of which are hallmarks of cellular aging throughout the body including the ovary. These findings are in alignment with the disposable soma theory of aging, which dictates a trade-off between growth, reproduction, and DNA repair. Therefore, delaying ovarian aging will not only increase the fertility window of middle age females, but may also actively prevent menopausal-related decline in systemic health parameters, compressing the period of morbidity in mid-to-late life in females.

Time-restricted feeding improves the reproductive function of female mice via liver fibroblast growth factor 21

Background

There has been a significant increase, to epidemic levels, of obese and overweight women of reproductive age, causing impairments to reproductive health. Time‐restricted feeding (TRF) including isocaloric intake has shown to be preventive of obesity‐related disorders. However, its therapeutic ability to improve the reproductive function of female remains largely unknown.

Methods

Here, we investigated the ability of TRF to improve the reproductive function in wild‐type and liver‐specific FGF21 knockout female mice. To study fertility, a continuous and a short‐term fertility test, gonadotropin releasing‐hormone (GnRH), and Kisspeptin test were performed. Immortalized GnRH neuron was used to examine the direct role of liver fibroblast growth factor 21 (FGF21) on GnRH secretion.

Results

We found that TRF rescues female mice from bodyweight gain and glucose intolerance, as well as ovarian follicle loss and dysfunction of estrus cyclicity induced by high‐fat diet. Furthermore, the beneficial effects of the TRF regimen on the reproductive performance were also observed in mice fed both chow and high‐fat diet. However, those beneficial effects of TRF on metabolism and reproduction were absent in liver‐specific FGF21 knockout mice. In vitro, FGF21 directly acted on GnRH neurons to modulate GnRH secretion via extracellular regulated protein kinases (ERK_1/2) pathway.

Conclusions

Overall, time‐restricted feeding improves the reproductive function of female mice and liver FGF21 signaling plays a key role in GnRH neuron activity in female mice.

High-fat diet leads to elevated lipid accumulation and endoplasmic reticulum stress in oocytes, causing poor embryo development

The present study was designed to investigate the effect of diet-induced obesity on endoplasmic reticulum (ER) stress in oocytes. Swiss albino mice (3 weeks old) were fed with a high-fat diet (HFD) for 8 weeks. Oocytes were assessed for lipid droplet accumulation, oxidative stress, ER stress and their developmental potential invitro. High lipid accumulation (P<0.01) and elevated intracellular levels of reactive oxygen species were observed in both germinal vesicle and MII oocytes of HFD-fed mice (P<0.05 and P<0.01 respectively compared with control). Further, expression of the ER stress markers X-box binding protein 1 (XBP1), glucose-regulated protein 78 (GRP78), activating transcription factor 4 (ATF4) and activating transcription factor 6 (ATF6) was significantly (P<0.001) higher in oocytes of the HFD than control group. Oocytes from HFD-fed mice exhibited poor fertilisation and blastocyst rates, a decrease in total cell number and high levels of DNA damage (P<0.01) compared with controls. In conclusion, diet-induced obesity resulted in elevated lipid levels and higher oxidative and ER stress in oocytes, which contributed to the compromised developmental potential of embryos.

Inflammation in Obesity-Related Complications in Children: The Protective Effect of Diet and Its Potential Role as a Therapeutic Agent

Obesity is a growing health problem in both children and adults, impairing physical and mental state and impacting health care system costs in both developed and developing countries. It is well-known that individuals with excessive weight gain frequently develop obesity-related complications, which are mainly known as Non-Communicable Diseases (NCDs), including cardiovascular disease, type 2 diabetes mellitus, metabolic syndrome, non-alcoholic fatty liver disease, hypertension, hyperlipidemia and many other risk factors proven to be associated with chronic inflammation, causing disability and reduced life expectancy. This review aims to present and discuss complications related to inflammation in pediatric obesity, the critical role of nutrition and diet in obesity-comorbidity prevention and treatment, and the impact of lifestyle. Appropriate early dietary intervention for the management of pediatric overweight and obesity is recommended for overall healthy growth and prevention of comorbidities in adulthood.

High-refined carbohydrate diet leads to polycystic ovary syndrome-like features and reduced ovarian reserve in female rats

Obesity is associated with several female reproductive complications, such as polycystic ovary syndrome (PCOS). The exact mechanism of this relationship remains unclear. Few previous studies using diet containing refined carbohydrate (HCD) leading to obesity have been performed and it is unclear if HCD is linked with reproductive dysfunctions. In this investigation, we assessed whether subchronic HCD exposure results in reproductive and other irregularities. Female rats were fed with HCD for 15 days and metabolic outcomes and reproductive tract morphophysiology were assessed. We further assessed reproductive tract inflammation, oxidative stress (OS) and fibrosis. HCD rats displayed metabolic impairments, such as an increase in body weight/adiposity, adipocyte hypertrophic, abnormal lipid profile, glucose tolerance and insulin resistance (IR) and hyperleptinemia. Improper functioning of the HCD reproductive tract was observed. Specifically, irregular estrous cyclicity, high LH levels and abnormal ovarian morphology coupled with reduction in primordial and primary follicle numbers was observed, suggesting ovarian reserve depletion. Improper follicular development and a reduction in antral follicles, corpora lutea and granulosa layer area together with an increase in cystic follicles were apparent. Uterine atrophy and reduction in endometrial gland (GE) number was observed in HCD rats. Reproductive tract inflammation, OS and fibrosis were seen in HCD rats. Further, strong positive correlations were observed between body weight/adiposity and IR with estrous cycle length, cystic follicles, ovarian reserve, GE and other abnormalities. Thus, these data suggest that the subchronic HCD exposure led to PCOS-like features, impaired ovarian reserve, GE number, and other reproductive abnormalities in female rats.

Effect of high-fat diet on the various morphological parameters of the ovary

Increased food consumption rich in fat and carbohydrate and sedentary lifestyle have seriously increased the rates of obesity and obesity-associated diseases in developed countries. Female mice with diet-induced obesity exhibit infertility and thus can serve as a model for human polycystic ovary syndrome. The aim of the present study was to examine how ovary is affected by diet-induced obesity. The effects of high-fat diet (HFD) on ovary morphology in mice fed with HFD were investigated using unbiased stereological methods. The ovary of mice fed with HFD (n=8, C1090-60, Altromine) for 9 weeks, were compared with that of mice fed with standard chow diet (n=8, C1090-10, Altromine). Stereological parameters were obtained in diestrus cycle. The samples were processed through routine and standard paraffin embedding and were serially sectioned in 5-µm thickness then, every 10th section was saved, stained with Crossman's triple stain for counting and measuring. In all sampled sections mean follicle numbers, diameters, total ovarian volume cortex to medulla ratio (Vv), ovum to cell ratio in secondary follicle were examined in all sampled sections. The present results showed that weight of ovarian and amount of intraperitoneal adipose tissue and the body weight markedly increased in obese mice when compared with control groups. Moreover, follicle numbers (except primordial follicles) and diameters were significantly increased in obese mice. Cortex to medulla ratio (Vv) and ovum to cell ratio in secondary follicle were also considerably different between experimental and the control groups. The present findings indicate that obesity adversely affects overall ovarian morphology.

Inflammaging is associated with shifted macrophage ontogeny and polarization in the aging mouse ovary

The fertility of women declines sharply after age 35 and is essentially lost upon menopause at age 51. The ovary plays an important part in aging-associated changes in women's physiology since it is an essential component of both the reproductive and endocrine systems. Several previous studies in mice have shown that the ovarian tissue goes through drastic changes over the course of aging and exhibits signs of aging-associated chronic inflammation (inflammaging), which may contribute to the marked decline of oocyte quality in aged individuals. To further examine aging-associated gene expression changes in the ovary and to characterize the development of inflammaging, we performed detailed transcriptomic analysis of whole ovaries from mice of six different age groups over the mouse reproductive lifespan and identified more than 5000 genes with significant expression change over the course of aging. Intriguingly, we found aging-associated changes in the expression of several markers that indicate alterations in the composition of ovarian macrophages, which are known to be central players of inflammaging. Using flow cytometry, we analyzed and compared macrophage populations and polarization in young and old ovaries and found a significant increase in monocyte recruitment and macrophage alternative activation (M2) in the old ovaries compared to those in young. Our results are consistent with previous findings of aging-associated increase of fibrosis in the ovarian stromal extracellular matrix, and they provide new clues about the development of inflammaging in the mammalian ovary.

Primordial follicle reserve, DNA damage and macrophage infiltration in the ovaries of the long-living Ames dwarf mice

The aim of this study was to evaluate the effect of growth hormone (GH) deficiency in primordial follicle reserve, DNA damage and macrophage infiltration in the ovaries of young mice. Ovaries from six-month-old GH-deficient Ames Dwarf (df/df) and Normal (N/df) mice were used. The number of primordial follicles was higher in df/df mice (p = 0.0026). Also, df/df mice had a lower number of primary (p = 0.023), secondary (p = 0.0052) and tertiary (p = 0.019) follicles. These findings indicate a slower rate of primordial follicle activation in df/df mice. Female df/df mice had decreased γH2AX foci intensity in oocytes of primordial (p = 0.015) and primary (p = 0.0004) follicles compared to N/df mice. Also, df/df mice had reduced γH2AX intensity in granulosa cells of primordial (p = 0.0002) and primary (p < 0.0001) follicles. Overall, this indicate to us that df/df mice accumulate less DNA damage in the ovarian reserve compared to N/df mice. Additionally, macrophage infiltration was also reduced in ovaries of df/df mice compared to N/df mice (p = 0.033). Interestingly, df/df mice had a reduced number of granulosa cells around primordial (p = 0.0024) and primary (p = 0.007) follicles compared to N/df mice. Also, df/df mice had a small diameter of primordial follicle nuclei (p = 0.0093), secondary follicle oocyte (p = 0.046) and tertiary follicle (p = 0.012). This points to the role of granulosa cell proliferation and oocyte growth for primordial follicle activation. The current study points to the role of the GH/IGF-I axis in extending lifespan of reproductive health, along with maintenance of oocyte DNA integrity and reduced ovarian inflammation.

Lipid droplets in granulosa cells are correlated with reduced pregnancy rates

BACKGROUND

Lipids are an important source for energy production during oocyte maturation. The accumulation of intracellular lipids binds to proteins to form lipid droplets. This may lead to cellular lipotoxicity. The impact of lipotoxicity on cumulus and granulosa cells has been reported. This pilot study evaluated their correlation to oocyte and embryo quality.

DESIGN

Prospective case-control study.

SETTING

Referral IVF unit.

PATIENTS

Women younger than age 40, undergoing IVF with intracytoplasmic sperm injection.

INTERVENTIONS

15 women with BMI > 30 (high BMI) and 26 women with BMI < 25 (low BMI) were enrolled. IVF outcomes were compared between groups based on BMI. Lipid content in cumulus and granulosa cells was evaluated using quantitative and descriptive methods. Lipid profile, hormonal profile and C-reactive protein were evaluated in blood and follicular fluid samples. Demographic and treatment data, as well as pregnancy rates were collected from electronic medical records.

RESULTS

Higher levels of LDL and CRP, slower cell division rate and lower embryo quality were found in the group with high BMI. There was no difference in pregnancy rates between groups. In light of these findings, treatment outcomes were reanalyzed according to patients who became pregnant and those who did not. We found that patients who conceived had significantly lower fat content in the granulosa cells, reflected by mean fluorescence intensity recorded by flow cytometry analysis (23,404 vs. 9370, P = 0.03).

CONCLUSIONS

BMI has no effect on lipid content in cumulus and granulosa cells, and does not affect likelihood of pregnancy. However, women who achieved pregnancy, regardless of their BMI, had lower lipid levels in their granulosa cells. This finding is important and further study is needed to evaluate lipid content in granulosa cells as a potential predictor of IVF treatment success.

High-fat diet-induced dysregulation of ovarian gene expression is restored with chronic omega-3 fatty acid supplementation

Chronic high-fat diet (HFD) consumption causes ovarian dysfunction in rodents. Acute dietary treatment with docosahexaenoic acid (DHA) increases oocyte quality and ovarian reserve at advanced reproductive age. We hypothesized that DHA supplementation after HFD exposure reverses HFD-induced ovarian defects. We conducted a dietary intervention with reversal to chow, DHA-supplemented chow, or DHA-supplemented HFD after HFD consumption. After 10 weeks, HFD-fed mice had impaired estrous cyclicity, decreased primordial follicles, and altered ovarian expression of 24 genes compared to chow controls. Diet reversal to either chow or chow + DHA restored estrous cyclicity, however only chow + DHA appeared to mitigated the impact of HFD on ovarian reserve. All dietary interventions restored HFD-dysregulated gene expression to chow levels. We found no association between follicular fluid DHA levels and ovarian reserve. In conclusion our data suggest some benefit of DHA supplementation after HFD, particularly in regards to ovarian gene expression, however complete restoration of ovarian function was not achieved.

Advancing metabolism research to overcome low litter survival in metabolically stressed mice

Elucidating the mechanism underlying the transmission of metabolic disease to subsequent generations requires robust preclinical mouse breeding strategies. Western diets rich in fat and carbohydrates are contributing factors in the rise of diabetes and obesity rates worldwide. Therefore, determining the impact of Western diets consumed by parents on offspring and future generations is critical for understanding the perpetuation of these diseases. Specifically, epigenetic regulation and transgenerational inheritance of metabolic disease is an emerging field of study requiring robust murine models. However, a major challenge to transgenerational studies is offspring mortality, exacerbated by maternal stress during pregnancy. Here, we describe a challenge experienced in our metabolic research in Western diet-fed female mice leading to the loss of litters via pup mortality and cannibalism by the mother. Furthermore, our study evaluates various breeding schemes with pregnancy efficiency and refined husbandry techniques to overcome pup mortality and infanticide, to characterize dams' and pups' metabolic characteristics, and to determine the impact on physiology of dams under detailed breeding schemes.

Thymoquinone ameliorates obesity-induced metabolic dysfunction, improves reproductive efficiency exhibiting a dose-organ relationship

Women with obesity are more likely to have a complicated reproductive life. Insulin resistance and metabolic dysfunction are associated with obesity. Thymoquinone (TQ) is a well-known antioxidant, considered to be an AMPK-activator. The goal of this work was to investigate the ability of TQ to improve fertility and lactation and clarify the possible mechanism. Female C57BL/6 mice were subjected to High Fat Diet (HFD) supplemented with TQ (10% pmm) and TQ (20% pmm). Histopathological examination was conducted on mammary and ovarian samples. Metabolic and oxidant status was evaluated, and qRT-PCR analysis was performed to verify AMPK/PGC1α/SIRT1 metabolic pathway activity. The present study reports positive effects of TQ on ovarian metabolic function in a dose-dependent manner. TQ showed its positive effects on mammary gland metabolic function at lower dose. This is the first study that indicates these dose related impacts of TQ. Abbreviations: AKT1: serine-threonine protein kinase 1; AMPK: 5' AMP-activated protein kinase; CAT: catalase; CON: control; FBS: fasting blood sugar; GLUT1: glucose transporter 1; GSH: reduced glutathione; GSSG: Glutathione disulfide; HE: hematoxylin and eosin stains; HDL: high-density lipoprotein; HFD: high fat diet; IL-6: interleukin-6; K18: keratin 18; LD: lactation day; LDL: low-density lipoprotein; LKB1: serine-threonine liver kinase B1; MDA: malondialdehyde; mTOR: the mammalian target of rapamycin; NAD: nicotinamide adenine dinucleotide; NADH: nicotinamide adenine dinucleotide phosphate; NS: nigella sativa; PBS: phosphate-buffered saline; PGC1α: peroxisome proliferator-activated receptor gamma coactivator 1-alpha; SIRT1: sirtuin 1; SOD: superoxide dismutase; T-AOC: total antioxidants; TFAM: transcription factor A mitochondrial; TG: triglycerides; TNF-α: tumor necrosis factor-α; TQ: thymoquinone; TQ10: high fat diet + thymoquinone 10% ppm; TQ20: high fat diet + thymoquinone 20% ppm; UCP2: uncoupling Protein 2.

Calcium Supplementation Alleviates High-Fat Diet-Induced Estrous Cycle Irregularity and Subfertility Associated with Concomitantly Enhanced Thermogenesis of Brown Adipose Tissue and Browning of White Adipose Tissue

Obesity has been demonstrated as a disruptor of female fertility. Our previous study showed the antiobesity effects of calcium on HFD-fed male mice. However, the role of calcium in alleviating reproductive dysfunction of HFD-fed female mice remains unclear. Here, we found that HFD led to estrus cycle irregularity (longer cycle duration and shorter estrus period) and subfertility (longer conception time, lower fertility index, and less implantations) in mice. However, the HFD-induced reproductive abnormality was alleviated by calcium supplementation. Additionally, calcium supplementation enhanced activation/thermogenesis of BAT and browning of WAT in HFD-fed mice. Consequently, the abnormality of energy metabolism and glucose homeostasis induced by HFD were improved by calcium supplementation, with elevated metabolic rates and core temperature. In conclusion, these data showed that calcium supplementation alleviated HFD-induced estrous cycle irregularity and subfertility associated with concomitantly enhanced BAT thermogenesis and WAT browning, suggesting the potential application of calcium in improving obesity-related reproductive disorders.

Low-Dose Tacrolimus Prevents Dysregulated Peri-Conceptional Ovarian and Systemic Immune Cellular Homeostasis in Subjects with PCOS

Polycystic ovary syndrome (PCOS) is characterized by failure of ovulation and is associated with obesity and chronic inflammation. Recent evidence suggests that anomalous activation of ovarian macrophages and numerical and functional deficits in the Th17 (CD4+IL17A+) and the CD4+CD25+CD127^low Tregs plays crucial role in PCOS. We have shown that the pre-pregnancy use of tacrolimus prevents adverse reproductive outcomes in a mouse model of PCOS. Here we used the HFD-NONcNZO mice to test a hypothesized beneficial use of tacrolimus relative to metformin in favorably influencing the ovarian and systemic immune milieux conducive to gestational success in subjects with PCOS. Compared to normative controls, our data revealed an aberrant peri-conceptional suppression of the CD4⁺CD25⁺CD127^low Tregs together with an overexpression of the Th17 T cells and lack of coordinated activation of ovarian macrophages in untreated HFD-dNONcNZO mice. Significant variances in treatment outcomes favoured the use of tacrolimus over metformin in treated mice. Consistent with the human fertility studies, this investigation reveals a beneficial systemic use of tacrolimus (0.1 mg/kg) in promoting early pregnancy in individuals with PCOS and suggests the need for further research into the selective inhibition of IL17A as a plausibly alternative immunotherapeutic approach in the clinical management of infertile individuals with PCOS.

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.