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

Impaired IL-27 signaling aggravates macrophage senescence and sensitizes premature ovarian insufficiency induction by high-fat diet

Premature ovarian insufficiency (POI) critically affects female reproductive health, with obesity being a significant and recognized risk factor. Interleukin-27 (IL-27), known for its role in immune modulation and inflammation, has garnered attention in metabolic syndrome research. Nonetheless, the role of these immunometabolic factors on the initiation of POI remains to be unraveled. Our investigation delves into the influence of impaired IL-27 signaling on POI induction, particularly under the challenge of a high-fat diet (HFD). We analyzed patients' serum profiles and established a correlation of increased serum triglycerides with decreased IL-27 levels in POI cases. Experiments on C57BL/6 mice lacking the IL-27 receptor alpha (Il27ra-/-) revealed that when subjected to HFD, these mice developed hallmark POI symptoms. This includes escalated lipid deposition in both liver and ovarian tissues, increased ovarian macrophages cellular aging, and diminished follicle count, all pointing to compromised ovarian function. These findings unveil a novel pathway wherein impaired IL-27 signaling potentiates the onset of POI in the presence of HFD. Understanding the intricate interplay between IL-27, metabolic alterations, and immune dysregulation sheds light on potential therapeutic avenues for managing POI, offering hope for improved reproductive health outcomes.

Effects of flaxseed oil supplementation on metaphase II oocyte rates in IVF cycles with decreased ovarian reserve: a randomized controlled trial

Background

This study was designed to explore the effects of flaxseed oil on the metaphase II (MII) oocyte rates in women with decreased ovarian reserve (DOR).

Methods

The women with DOR were divided into a study group (n = 108, flaxseed oil treatment) and a control group (n = 110, no treatment). All patients were treated with assisted reproductive technology (ART). Subsequently, the ART stimulation cycle parameters, embryo transfer (ET) results, and clinical reproductive outcomes were recorded. The influencing factors affecting the MII oocyte rate were analyzed using univariate analysis and multivariate analysis.

Results

Flaxseed oil reduced the recombinant human follicle-stimulating hormone (r-hFSH) dosage and stimulation time and increased the peak estradiol (E2) concentration in DOR women during ART treatment. The MII oocyte rate, fertilization rate, cleavage rate, high-quality embryo rate, and blastocyst formation rate were increased after flaxseed oil intervention. The embryo implantation rate of the study group was higher than that of the control group (p = 0.05). Additionally, the female age [odds ratio (OR): 0.609, 95% confidence interval (CI): 0.52-0.72, p < 0.01] was the hindering factor of MII oocyte rate, while anti-Müllerian hormone (AMH; OR: 100, 95% CI: 20.31-495, p < 0.01), peak E2 concentration (OR: 1.00, 95% CI: 1.00-1.00, p = 0.01), and the intake of flaxseed oil (OR: 2.51, 95% CI: 1.06-5.93, p = 0.04) were the promoting factors for MII oocyte rate.

Conclusion

Flaxseed oil improved ovarian response and the quality of oocytes and embryos, thereby increasing the fertilization rate and high-quality embryo rate in DOR patients. The use of flaxseed oil was positively correlated with MII oocyte rate in women with DOR.

Clinical trial number

https://www.chictr.org.cn/, identifier ChiCTR2300073785.

The transcriptome reveals the molecular regulatory network of primordial follicle depletion in obese mice

OBJECTIVE

To explore the dynamic transcriptional regulatory network of primordial follicle fate in obese mice to elucidate the potential mechanism of primordial follicle depletion.

DESIGN

Experimental study and transcriptomic analysis.

ANIMALS

Healthy (n=15) and obese (n=15) female mice.

INTERVENTIONS

Six-week-old CD-1 mice were divided into healthy and high-fat diet groups and fed continuously for 12 weeks. The diet of healthy mice contained 10% fat. The diet of high-fat mice contained 60% fat.

MAIN OUTCOME MEASURES

Primordial to primary follicle transition rate, gene expression changes, enriched Kyoto Encyclopedia of Genes and Genomes pathways, and ferroptosis.

RESULTS

Primordial follicle depletion was increased in the ovaries of obese mice. We found that deposited fat around primordial and primary follicles of obese mice was higher than that for healthy mice. The proliferation of granulosa cells around primary follicles was increased in obese mice. In addition, we uncovered specific gene signatures associated with the primordial to primary follicle transition (PPT) in obese mice using laser capture microdissection RNA sequencing analysis. Gene set enrichment analysis indicated that ferroptosis, cell oxidation, vascular endothelial growth factor, and mammalian target of rapamycin signaling were increased significantly in the primordial follicles of obese mice. Notably, the ferritin, acyl CoA synthetase long-chain family member 4, and solid carrier family 7 member 11 associated proteins of the ferroptosis signaling pathway were significantly increased in the PPT phase of obese mice.

CONCLUSION

Our work suggests that ferroptosis is a key pathway activated within immature ovarian follicles in the context of obesity and that the process may be involved in the physiological regulation of the PPT as well.

The Role of Lifestyle and Dietary Factors in the Development of Premature Ovarian Insufficiency

Premature ovarian insufficiency (POI) is a condition that arises from dysfunction or early depletion of the ovarian follicle pool accompanied by an earlier-than-normal loss of fertility in young women. Oxidative stress has been suggested as an important factor in the decline of fertility in women and POI. In this review, we discuss the mechanisms of oxidative stress implicated in ovarian ageing and dysfunction in relation to POI, in particular mitochondrial dysfunction, apoptosis and inflammation. Genetic defects, autoimmunity and chemotherapy, are some of the reviewed hallmarks of POI that can lead to increased oxidative stress. Additionally, we highlight lifestyle factors, including diet, low energy availability and BMI, that can increase the risk of POI. The final section of this review discusses dietary factors associated with POI, including consumption of oily fish, mitochondria nutrient therapy, melatonin, dairy and vitamins that can be targeted as potential interventions, especially for at-risk women and in combination with personalised nutrition. Understanding the impact of lifestyle and its implications for POI and oxidative stress holds great promise in reducing the burden of this condition.

Mitochondrial dysfunction in the offspring of obese mothers and it's transmission through damaged oocyte mitochondria: Integration of mechanisms

In vivo and in vitro studies demonstrate that mitochondria in the oocyte, are susceptible to damage by suboptimal pre/pregnancy conditions, such as obesity. These suboptimal conditions have been shown to induce mitochondrial dysfunction (MD) in multiple tissues of the offspring, suggesting that mitochondria of oocytes that pass from mother to offspring, can carry information that can programme mitochondrial and metabolic dysfunction of the next generation. They also suggest that transmission of MD could increase the risk of obesity and other metabolic diseases in the population inter- and trans-generationally. In this review, we examined whether MD observed in offspring tissues of high energetic demand, is the result of the transmission of damaged mitochondria from obese mothers' oocytes to the offspring. The contribution of genome-independent mechanisms (namely mitophagy) in this transmission were also explored. Finally, potential interventions aimed at improving oocyte/embryo health were investigated, to see if they may provide an opportunity to halter the generational effects of MD.

Maternal circadian disruption before pregnancy impairs the ovarian function of female offspring in mice

Circadian disturbance brought on by shift employment, nighttime light pollution, and other factors is quite prevalent in contemporary culture. However, the effect of maternal circadian disruption before pregnancy on the reproduction of offspring in mice requires further research. Herein, we exposed female ICR mice to constant light to establish a model of preconceptional circadian disruption and then checked the ovarian function of female offspring (named the CLE group below). Our results revealed obesity, abnormal lipid metabolism and earlier puberty onset in the CLE group. Additionally, impaired ovarian follicle development, oocyte quality and preimplantation embryo development were shown in the CLE group. Moreover, the expression levels of Gnrh1 in the hypothalamus and Cyp17a1, Bmper, Bdnf and Lyve1 in ovaries, as well as circadian clock genes, including Clock, Cry1, Nr1d2 and Per2, were significantly downregulated in the CLE group. Mechanistically, immune responses, including the interleukin-17 (IL-17) signalling pathway, cytokine-cytokine receptor interaction and the chemokine signalling pathway, were altered in the CLE group, which may be responsible for the damaged ovarian function.

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.

High-Fat Diet and Female Fertility across Lifespan: A Comparative Lesson from Mammal Models

Female reproduction focuses mainly on achieving fully grown follicles and competent oocytes to be successfully fertilized, as well as on nourishing the developing offspring once pregnancy occurs. Current evidence demonstrates that obesity and/or high-fat diet regimes can perturbate these processes, leading to female infertility and transgenerational disorders. Since the mechanisms and reproductive processes involved are not yet fully clarified, the present review is designed as a systematic and comparative survey of the available literature. The available data demonstrate the adverse influences of obesity on diverse reproductive processes, such as folliculogenesis, oogenesis, and embryo development/implant. The negative reproductive impact may be attributed to a direct action on reproductive somatic and germinal compartments and/or to an indirect influence mediated by the endocrine, metabolic, and immune axis control systems. Overall, the present review highlights the fragmentation of the current information limiting the comprehension of the reproductive impact of a high-fat diet. Based on the incidence and prevalence of obesity in the Western countries, this topic becomes a research challenge to increase self-awareness of dietary reproductive risk to propose solid and rigorous preventive dietary regimes, as well as to develop targeted pharmacological interventions.

Female infertility and diet, is there a role for a personalized nutritional approach in assisted reproductive technologies? A Narrative Review

Female infertility is a major public health concern and a global challenge. It is a disorder of the reproductive system, defined as the inability to achieve a clinical pregnancy. Nutrition and other environmental factors are found to impact reproductive health in women as well as the outcome of assisted reproductive technologies (ART). Dietary factors, such as polyunsaturated fatty acids (PUFA), fiber as well as the intake of Mediterranean diet appear to exert beneficial effects on female reproductive outcomes. The exact mechanisms associating diet to female fertility are yet to be identified, although genomic, epigenomic, and microbial pathways may be implicated. This review aims to summarize the current knowledge on the impact of dietary components on female reproduction and ART outcomes, and to discuss the relevant interplay of diet with genome, epigenome and microbial composition.

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.

Short-Term Adaptations in Skeletal Muscle Mitochondrial Oxidative Capacity and Metabolic Pathways to Breaking up Sedentary Behaviors in Overweight or Obese Adults

Breaking up sedentary behavior with short-frequent bouts of physical activity (PA) differentially influences metabolic health compared with the performance of a single-continuous bout of PA matched for total active time. However, the underlying mechanisms are unknown. We compared skeletal muscle mitochondrial respiration (high-resolution respirometry) and molecular adaptations (RNA sequencing) following 4-day exposure to breaks vs. energy-matched single-continuous PA bout in inactive adults with overweight/obesity. Participants (9M/10F, 32.2 ± 6.4 years, 30.3 ± 3.0 kg/m2) completed three 4-day interventions of a randomized cross-over study: SED, sedentary control; MICRO, 5 min brisk walking each hour for 9 h; ONE: 45 min/d continuous brisk walking bout. Fasted muscle biopsies were collected on day 5. Mitochondrial coupling in the presence of lipid-associated substrates was higher after ONE (4.8 ± 2.5) compared to MICRO (3.1 ± 1.1, p = 0.02) and SED (2.3 ± 1.0, p = 0.001). Respiratory rates did not differ across groups with carbohydrate-associated substrates. In pathways associated with muscle contraction transcription signaling, ONE and MICRO similarly enhanced Oxidative Phosphorylation and Sirtuin Signaling expression (p < 0.0001, for both). However, ONE (p < 0.001, for all), but not MICRO, had greater pathway enrichment, including Ca++, mTOR, AMPK, and HIF1α signaling, than SED. Although breaking up sedentary behavior triggered skeletal muscle molecular adaptations favoring oxidative capacity, it did not improve mitochondrial function over the short term.

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.

Tributyltin and high-refined carbohydrate diet lead to metabolic and reproductive abnormalities, exacerbating premature ovary failure features in the female rats

Exposure to the obesogen tributyltin (TBT) alone or high carbohydrate diet (HCD) alone leads to obesity and reproductive complications, such as premature ovary failure (POF) features. However, little is known about interactions between TBT and nutrition and their combined impact on reproduction. In this study, we assessed whether acute TBT and HCD exposure results in reproductive and metabolic irregularities. Female rats were treated with TBT (100 ng/kg/day) and fed with HCD for 15 days and metabolic and reproductive outcomes were assessed. TBT and HCD rats displayed metabolic impairments, such as increased adiposity, abnormal lipid profile and triglyceride and glucose (TYG) index, worsening adipocyte hypertrophy in HCD-TBT rats. These metabolic consequences were linked with reproductive disorders. Specifically, HCD-TBT rats displayed irregular estrous cyclicity, high follicle-stimulating hormone (FSH) levels, low anti-Müllerian hormone (AMH) levels, reduction in ovarian reserve, and corpora lutea (CL) number, with increases in atretic follicles, suggesting that HCD-TBT exposure exacerbated POF features. Further, strong negative correlations were observed between adipocyte hypertrophy and ovarian reserve, CL number and AMH levels. HCD-TBT exposure resulted in reproductive tract inflammation and fibrosis. Collectively, these data suggest that TBT plus HCD exposure leads to metabolic and reproductive abnormalities, exacerbating POF features in female rats.

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.