Obesity induced by cafeteria diet disrupts fertility in the rat by affecting multiple ovarian targets

Shear wave elastography to assess stiffness of the human ovary and other reproductive tissues across the reproductive lifespan in health and disease†

The ovary is one of the first organs to show overt signs of aging in the human body, and ovarian aging is associated with a loss of gamete quality and quantity. The age-dependent decline in ovarian function contributes to infertility and an altered endocrine milieu, which has ramifications for overall health. The aging ovarian microenvironment becomes fibro-inflammatory and stiff with age, and this has implications for ovarian physiology and pathology, including follicle growth, gamete quality, ovulation dynamics, and ovarian cancer. Thus, developing a non-invasive tool to measure and monitor the stiffness of the human ovary would represent a major advance for female reproductive health and longevity. Shear wave elastography is a quantitative ultrasound imaging method for evaluation of soft tissue stiffness. Shear wave elastography has been used clinically in assessment of liver fibrosis and characterization of tendinopathies and various neoplasms in thyroid, breast, prostate, and lymph nodes as a non-invasive diagnostic and prognostic tool. In this study, we review the underlying principles of shear wave elastography and its current clinical uses outside the reproductive tract as well as its successful application of shear wave elastography to reproductive tissues, including the uterus and cervix. We also describe an emerging use of this technology in evaluation of human ovarian stiffness via transvaginal ultrasound. Establishing ovarian stiffness as a clinical biomarker of ovarian aging may have implications for predicting the ovarian reserve and outcomes of Assisted Reproductive Technologies as well as for the assessment of the efficacy of emerging therapeutics to extend reproductive longevity. This parameter may also have broad relevance in other conditions where ovarian stiffness and fibrosis may be implicated, such as polycystic ovarian syndrome, late off target effects of chemotherapy and radiation, premature ovarian insufficiency, conditions of differences of sexual development, and ovarian cancer. Summary sentence:  Shear Wave Elastography is a non-invasive technique to study human tissue stiffness, and here we review its clinical applications and implications for reproductive health and disease.

Diagnostic Performance of Ovarian Morphology on Ultrasonography across Anovulatory Conditions-Impact of Body Mass Index

The study objectives were to determine whether ovarian morphology can distinguish between women with regular menstrual cycles, normo-androgenic anovulation (NA-Anov), and PCOS and whether body mass index (BMI)-specific thresholds improved diagnostic potential. Women with PCOS (biochemical and/or clinical hyperandrogenism and irregular cycles; N = 66), NA-Anov (irregular cycles without clinical and/or biochemical hyperandrogenism; N = 64), or regular cycles (controls; cycles every 21-35 days in the absence of clinical or biochemical hyperandrogenism; N = 51) were evaluated. Participants underwent a reproductive history, physical exam, transvaginal ultrasound, and a fasting blood sample. Linear regression analyses were used to assess the impact of BMI on ovarian morphology across groups. The diagnostic performance of ovarian morphology for anovulatory conditions, and by BMI (lean: <25 kg/m²; overweight: ≥25 kg/m²), was tested using Receiver Operating Characteristic (ROC) curves. Follicle number per ovary (FNPO) and ovarian volume (OV), but not follicle number per cross-section (FNPS), increased across controls, NA-Anov, and PCOS. Overall, FNPO had the best diagnostic performance for PCOS versus controls (AUC_ROC = 0.815) and NA-Anov and controls (AUC_ROC = 0.704), and OV to differentiate between PCOS and NA-Anov (AUC_ROC = 0.698). In lean women, FNPO best differentiated between PCOS and controls (AUC_ROC = 0.843) and PCOS versus NA-Anov (AUC_ROC = 0.710). FNPS better distinguished between NA-Anov and controls (AUC_ROC = 0.687), although diagnostic performance was lower than when thresholds were generated using all participants. In women with overweight and obesity, OV persisted as the best diagnostic feature across all analyses (PCOS versus control, AUC_ROC = 0.885; PCOS versus NA-Anov, AUC_ROC = 0.673; NA-Anov versus controls, AUC_ROC = 0.754). Ovarian morphology holds diagnostic potential to distinguish between NA-Anov and PCOS, with marginal differences in diagnostic potential when participants were stratified by BMI suggesting that follicle number may provide better diagnostic performance in lean women and ovarian size in those with overweight.

Maternal exposure to di(2-ethylhexyl) phthalate (DEHP) causes multigenerational adverse effects on the uterus of F1 and F2 offspring rats

Phthalates are one of the ubiquitous chemicals found in day-to-day products like food packaging, children's toys, and other consumer commodities. There is rising concern that repeated exposure to phthalates during pregnancy and lactation could have long-term effects on maternal and fetal health. We hypothesize that exposure to DEHP during the developmental windows might affect the expression of molecules that regulate uterine function and that this effect would be passed on to further generations. Rat dams were treated with olive oil (vehicle) or DEHP (100 mg/kg b.wt./day) orally from gestational day 9 (GD 9) to the end of lactation (PND 21). F₀ maternal DEHP exposure resulted in multigenerational (F₁ and F₂) reproductive toxicity, as evidenced by an extended estrous cycle, decreased mating, fertility, and fecundity indices. Serum progesterone and estradiol levels were decreased and their cognate receptors (PR and ERα) in the uterus were decreased in the DEHP-exposed offspring rats. Further analysis of the expression of estrogen and progesterone regulatory genes such as Hox a11, VEGF A, Ihh, LIFR, EP4, PTCH, NR2F2, BMP2, and Wnt4 were reduced in the uteri of adult F₁ and F₂ generation rats born from DEHP-exposed F₀ dams. Decreased expression of these crucial proteins due to DEHP exposure may lead to defects in epithelial proliferation and secretion, uterine receptivity, and decidualization in the uteri of successive generations. This study showed that maternal DEHP exposure impairs the expression of molecules that regulate uterine function and this multigenerational effect is transmitted via maternal lineage.

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.

Anti-obesity potential of Moringa olifera seed extract and lycopene on high fat diet induced obesity in male Sprauge Dawely rats

Present research explored the anti-obesity effect of Moringa olifera seed oil extract and lycopene (LYC). Forty eight male Sprauge Dawely rats were divided equally into 6 groups. Group Ι (C) served as control, group ΙΙ (MC) was given Moringa olifera seed oil extract (800 mg/kg b.wt) for 8 weeks, group ΙΙΙ (LC) was given (20 mg/kg b.wt) LYC for 8 weeks, group ΙV (O) received high fat diet (HFD) for 20 weeks, group Ѵ (MO), was given HFD for 20 weeks and received (800 mg/kg b.wt) Moringa olifera seed oil extract for last 8 weeks and group ѴΙ (LO), received HFD for 20 weeks and was given (20 mg/kg b.wt) LYC for last 8 weeks. Hematology, lipid peroxidation and antioxidants, non-esterified fatty acids (NEFA), glucose, lipid profile, serum liver and kidney biomarkers, inflammatory markers, leptin, resistin and heart fatty acid binding protein (HFABP) were determined. Also histopathology for liver, kidney and aorta were performed besides immunohistochemistry (IHC) for aortic inducible nitric oxide synthase (iNOS). Administration of Moringa olifera seed oil extract and LYC significantly ameliorated the HFD induced hematological and metabolic perturbations as well as reduced leptin and resistin. Both treatments exerted these effects through promotion of antioxidant enzymes and reducing lipid peroxidation as well as inflammatory cytokines along with reduced iNOS protein expression. Administration of Moringa olifera seed oil extract and LYC have anti-obesity potential in HFD induced obesity in male Sprauge Dawely rats.

Resveratrol attenuates metabolic, sperm, and testicular changes in adult Wistar rats fed a diet rich in lipids and simple carbohydrates

High-fat diets affect male reproduction and sexual function. Therefore, we evaluated the effects of prolonged resveratrol administration on the metabolic, sperm, and testicular parameters of rats fed a cafeteria diet. Male Wistar rats were divided at weaning into control (C, n = 20) and cafeteria (CAF, n = 16) groups. At 3 months, half of them were given daily supplementations of resveratrol (C-R, n = 10; CAF-R, n = 8) at a dosage of 30 mg kg^-1 body mass for 2 months. Animals were killed at 5 months of age, and blood, spermatozoa, and testes were collected for further analysis. Data were analyzed by one-way ANOVA, and P < 0.05 was considered statistically significant. The CAF diet promoted hyperglycemia (P < 0.0001), and treatment with resveratrol reversed this condition (P < 0.0001). The CAF diet reduced sperm viability and motility, while resveratrol improved these parameters (P < 0.05). Regarding testicular morphology, the height of the seminiferous epithelium was reduced in the CAF group compared with that of the C group (P = 0.0007). Spermatogenic cell proliferation was also reduced in the CAF group compared with that of the C group. However, the CAF-R showed an increase in cell proliferation rate compared with that of the untreated CAF group (P = 0.0024). Although it did not modify body mass, the consumption of a CAF diet promoted hyperglycemia, adverse testicular morphology remodeling, and abnormal sperm, which were attenuated by treatment with resveratrol, thus suggesting a protective effect of this antioxidant on spermatogenesis.

Aromatase Inhibition Ameliorates Decreased LH Output Found in Obese Women

In obese ovulatory women, serum luteinizing Hormone (LH) and follicle stimulating hormone (FSH) are lowered compared with normal weight women. This relative hypogonadotropic hypogonadism represents a potential etiology for overall decreased fertility in obesity. The objective was to determine if administration of an aromatase inhibitor (AI) to ovulating obese women would normalize LH and FSH by interrupting estradiol negative feedback. Letrozole (2.5-5 mg) was given daily to 22 women, 12 obese and 10 normal weight, for 7 days. On the last day of administration, 8 h of blood sampling was done every 10 min before and after a bolus of GnRH at 4 h. We obtained data from 21 ovulatory women (10 normal weight and 11 obese) who had undergone a similar protocol of frequent blood sampling but no aromatase inhibitors (AI) treatment. Serum LH and FSH levels and pulse characteristics were measured. Treatment with AI only significantly affected obese women. Further, in women with obesity, LH secretion, prior to the GnRH bolus, was significantly higher in AI treated compared with non-treated (p = 0.011). AI treatment doubled LH pulse amplitude in obese women (p = 0.004). In response to aromatase inhibition, LH secretion in ovulatory women with obesity is increased and similar to levels found in untreated normal weight women. The increase in LH pulse amplitude indicates that the AI effect is mediated at the level of the pituitary. Our results suggest that the hypogonadotropic phenotype of simple obesity is subject to modulation by interruption of estradiol negative feedback.

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

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

Effect of troxerutin on apelin-13, apelin receptors (APJ), and ovarian histological changes in the offspring of high-fat diet fed rats

OBJECTIVES

Maternal high-fat diet (HFD) consumption has been linked to metabolic disorders and reproductive dysfunctions in offspring. Troxerutin (TRO) has anti-hyperlipidemic, anti-oxidant, and anti-inflammatory effects. This study examined the effects of TRO on apelin-13, its receptors mRNA and ovarian histological changes in the offspring of HFD fed rats.

MATERIALS AND METHODS

Female Wistar rats were randomly divided into control diet (CD) or HFD groups and received these diets for eight weeks. After mating, dams were assigned into four subgroups: CD, CD + TRO, HFD, and HFD + TRO, and received their respective diets until the end of lactation. Troxerutin (150 mg/kg/day) was gavaged in the CD + TRO and HFD + TRO groups during pregnancy. On the postnatal day (PND) 21 all female offspring were separated and fed CD until PND 90. On PND 90 animals were sacrificed and ovarian tissue samples were collected for further evaluation.

RESULTS

Results showed that HFD significantly decreased serum apelin-13 in the female offspring of the HFD dams, which was significantly reversed by TRO. Moreover, real-time polymerase chain reaction (PCR) analysis revealed that TRO treatment significantly decreased the ovarian mRNA expression of the apelin-13 receptor in the troxerutin-received offspring. Furthermore, histological examination revealed that TRO increased the number of atretic follicles in the ovaries of HFD+TRO offspring.

CONCLUSION

Maternal high fat feeding compromises ovarian health including follicular growth and development in the adult offspring and troxerutin treatment improved negative effects of maternal HFD on the apelin-13 level and ovarian development of offspring.

Preclinical Models of Altered Early Life Nutrition and Development of Reproductive Disorders in Female Offspring

Early epidemiology studies in humans have and continue to offer valuable insight into the Developmental Origins of Health and Disease (DOHaD) hypothesis, which emphasises the importance of early-life nutritional and environmental changes on the increased risk of metabolic and reproductive disease in later life. Human studies are limited and constrained by a range of factors which do not apply to preclinical research. Animal models therefore offer a unique opportunity to fully investigate the mechanisms associated with developmental programming, helping to elucidate the developmental processes which influence reproductive diseases, and highlight potential biomarkers which can be translated back to the human condition. This review covers the use and limitations of a number of animal models frequently utilised in developmental programming investigations, with an emphasis on dietary manipulations which can lead to reproductive dysfunction in offspring.

Induction of uterine hyperplasia after cafeteria diet exposure

Our aim was to evaluate whether chronic administration of CAF affects the uterus and induces the morphological and molecular changes associated with endometrial hyperplasia. Female Wistar rats exposed to CAF from weaning for 20 weeks displayed increased energy intake, body weight and fat depots, but did not develop metabolic syndrome. The adult uteri showed an increase in glandular volume fraction and stromal area. The epithelial proliferation rate and protein expression of oestrogen receptor alpha (ERα) were also increased. The CAF diet enhanced leptin serum levels and the long form of leptin receptor (Ob-Rb) mRNA expression in the uterus. No changes were detected in either insulin serum levels or those of insulin growth factor I (IGF-I) mRNA expression. However the levels of IGF-I receptor (IGF-IR) mRNA were lower in CAF-fed animals. Overall, the results indicate that our rat model of the CAF diet produces morphological and molecular changes associated with uterine hyperplasia and could predispose to endometrial carcinogenesis.

Obesity alters the uterine environment before pregnancy

Obesity is a metabolic disorder that predisposes to numerous diseases and has become a major global public health concern. Cafeteria diet (CAF) is the animal model used for the study of obesity that more closely reflects Western diet habits. Previously, we described that CAF administration for 60 days induces obesity in female rats and their fetuses develop macrosomia. Given that, in our model, rats are not genetically modified and that obese mothers were fed standard chow during pregnancy, the aim of the current study was to test the hypothesis that obesity alters the intrauterine environment prior to pregnancy, and this may explain the exacerbated fetal weight gain. We found that uteri from obese rats during the estrous phase developed insulin resistance through mechanisms that involve the induction of uterine hypoxia and the down-regulation of the insulin receptor gene. Moreover, uterine cell proliferation was induced by obesity concomitantly with the reduction in the uterine contractile response to a β2 AR agonist, salbutamol, and this may be consequence of the down-regulation in the uterine β2 AR expression. We conclude that CAF-induced obesity alters the uterine environment in rats during the estrous phase and may cause the fetal macrosomia previously described by us in obese animals. The lower sensitivity of the uterus to a relaxation stimulus (salbutamol) is not a minor fact given that for implantation to occur the uterus must be relaxed for embryo nidation. Thus, the alteration in the uterine quiescence may impair implantation and, consequently, the foregoing pregnancy.

High-fat diet exposure, regardless of induction of obesity, is associated with altered expression of genes critical to normal ovulatory function

We evaluated the impact of high-fat diet (HFD) on ovarian gene expression. Female 5-week-old C57BL/6J mice were fed a 60% HFD or standard chow for 10 weeks. HFD-fed mice were then separated into obese (HF-Ob) and lean (HF-Ln) based on body weight. HFD exposure led to impairment of the estrous cycle, changes in hormones affecting reproduction, and decreased primordial follicles regardless of the development of obesity. RNA-sequencing of whole ovaries identified multiple genes with altered expression after HFD, with 25 genes displaying decreased expression in both HF-Ln and HF-Ob mice compared to the chow-fed controls (q < 0.05). Several of these 25 genes are involved in normal ovarian functions, including ovulation (Edn2, Tnfaip6, Errfi1, Prkg2, and Nfil3), luteinization (Edn2), and luteolysis (Nr4a1). Taken together, elevated dietary fat intake, regardless of obesity, is associated with impaired estrous cycle, depletion of the ovarian reserve, and altered expression of genes critical to normal ovulatory function.

Effect of the induction of transgenerational obesity on maternal-fetal parameters

Maternal obesity can cause complications for both women and their offspring for generations. Therefore, we intended to verify the repercussions of induction of transgenerational obesity on biochemical parameters, reproductive performance, and congenital anomaly frequency in Wistar rats. Female rats were used from successive generations. The female rats of parental generation (F₀, n=10) were mated to obtain their offspring (F₁ generation). F₁ female rats received a monosodium glutamate (MSG) solution to induce obesity (n=07) or vehicle (control, n=06) during the neonatal period. These adult female rats were classified as normal or obese using the Lee Index, mated, and delivered offspring (F₂ generation), which were also evaluated for obesity using the Lee Index in adult life (F₂MSG, n=13, born from obese dams) or non-obesity status (F₂Control, n=12, born from control dams), and were mated in adulthood. During pregnancy, glycemia and an oral glucose tolerance test (OGTT) were analyzed. At term pregnancy, the females were sacrificed for serum biochemical profile, maternal reproductive outcomes, and fetal development. In F₂MSG rats, body weight gain at early pregnancy, glycemia by OGTT, total cholesterol, high-density-lipoprotein, and alanine transaminase activity were higher compared with those of F₂Control rats. F₂MSG rats also presented a lower implantation number and gravid uterus weight, increased pre-implantation loss and anomaly frequency in their fetuses (F₃ generation) compared with those of F₂Control rats. Therefore, even without significant changes in body weight gain, obesity was established at the end of pregnancy of Wistar rats using other biomarkers. Additionally, these rats showed multiple adverse reproductive outcomes, confirming the deleterious effects that lead to obesity.

Detrimental effect of maternal and post-weaning high-fat diet on the reproductive function in the adult female offspring rat: roles of insulin-like growth factor 2 and the ovarian circadian clock

PURPOSE

We evaluate the impact of maternal and post-weaning high-fat (HF) diet on ovarian follicular population, steroidogenesis, and gene expression with a focus on the circadian clock system and insulin-like growth factor 2 (Igf2) in adult offspring ovaries, and to elucidate whether a maternal and post-weaning diet confers similar risks.

METHODS

Virgin Sprague-Dawley rats were fed with normal chow (C) diet or HF diet for 5 weeks before mating, during gestation, and lactation. Female offspring were fed with the C or HF diet from weaning to 6 months of age, resulting in four study groups (n = 6 per group): C/C, C/HF, HF/C, and HF/HF.

RESULTS

Ovaries from offspring exposed to post-weaning HF diet (i.e., the C/HF and HF/HF groups) had a decrease in small follicle numbers, but with similar numbers of antral follicles and corpora lutea. Offspring from HF-fed dams (i.e., the HF/C and HF/HF groups) had increased plasma estradiol concentrations and decreased luteinizing hormone levels at 6 months of age. In addition, Igf2 and each of the circadian rhythm core genes Clock, Per1, Per2, and Per3 were increased in the ovaries of offspring exposed to maternal HF diet (both HF/C and HF/HF groups).

CONCLUSIONS

Maternal and post-weaning HF diet programs the reproductive profile of the female offspring in adult life through different manners. Post-weaning HF intake resulted in the reduction of small follicles in adulthood, whereas maternal HF diet had long-term deleterious consequences on female offspring steroidogenesis and coincided with alteration of the upregulation of the imprinted gene Igf2 and changes in ovarian circadian rhythms.

Hypothyroidism Reduces the Size of Ovarian Follicles and Promotes Hypertrophy of Periovarian Fat with Infiltration of Macrophages in Adult Rabbits

Ovarian failure is related to dyslipidemias and inflammation, as well as to hypertrophy and dysfunction of the visceral adipose tissue (VAT). Although hypothyroidism has been associated with obesity, dyslipidemias, and inflammation in humans and animals, its influence on the characteristics of ovarian follicles in adulthood is scarcely known. Control and hypothyroid rabbits were used to analyze the ovarian follicles, expression of aromatase in the ovary, serum concentration of lipids, leptin, and uric acid, size of adipocytes, and infiltration of macrophages in the periovarian VAT. Hypothyroidism did not affect the percentage of functional or atretic follicles. However, it reduced the size of primary, secondary, and tertiary follicles considered as large and the expression of aromatase in the ovary. This effect was associated with high serum concentrations of total cholesterol and low-density lipoprotein cholesterol (LDL-C). In addition, hypothyroidism induced hypertrophy of adipocytes and a major infiltration of CD68+ macrophages into the periovarian VAT. Our results suggest that the reduced size of ovarian follicles promoted by hypothyroidism could be associated with dyslipidemias, hypertrophy, and inflammation of the periovarian VAT. Present findings may be useful to understand the influence of hypothyroidism in the ovary function in adulthood.