Cellular and molecular aspects of ovarian follicle ageing

The role of cellular senescence in female reproductive aging and the potential for senotherapeutic interventions

BACKGROUND

Advanced maternal age is associated with decreased oocyte quantity and quality as well as uterine and placental dysfunctions. These changes lead to infertility, pregnancy complications and birth defects in the offspring. As the mean age of giving birth is increasing worldwide, prevention of age-associated infertility and pregnancy complications, along with the more frequent use of ART, become extremely important. Currently, significant research is being conducted to unravel the mechanisms underlying female reproductive aging. Among the potential mechanisms involved, recent evidence has suggested a contributing role for cellular senescence, a cellular state of irreversible growth arrest characterized by a hypersecretory and pro-inflammatory phenotype. Elucidating the role of senescence in female reproductive aging holds the potential for developing novel and less invasive therapeutic measures to prevent or even reverse female reproductive aging and increase offspring wellbeing.

OBJECTIVE AND RATIONALE

The review will summarize the positive and negative implications of cellular senescence in the pathophysiology of the female reproductive organs during aging and critically explore the use of novel senotherapeutics aiming to reverse and/or eliminate their detrimental effects. The focus will be on major senescence mechanisms of the ovaries, the uterus, and the placenta, as well as the potential and risks of using senotherapies that have been discovered in recent years.

SEARCH METHODS

Data for this review were identified by searches of MEDLINE, PubMed and Google Scholar. References from relevant articles using the search terms ‘Cellular Senescence’, ‘Aging’, ‘Gestational age’, ‘Maternal Age’, ‘Anti-aging’, ‘Uterus’, ‘Pregnancy’, ‘Fertility’, ‘Infertility’, ‘Reproduction’, ‘Implant’, ‘Senolytic’, ‘Senostatic’, ‘Senotherapy’ and ‘Senotherapeutic’ where selected. A total of 182 articles published in English between 2005 and 2020 were included, 27 of which focus on potential senotherapies for reproductive aging. Exclusion criteria were inclusion of the terms ‘male’ and ‘plants’.

OUTCOMES

Aging is a major determinant of reproductive wellbeing. Cellular senescence is a basic aging mechanism, which can be exploited for therapeutic interventions. Within the last decade, several new strategies for the development and repurposing of drugs targeting senescent cells have emerged, such as modulators of the anti-inflammatory response, oxidative stress, DNA damage, and mitochondria and protein dysfunctions. Several studies of female reproductive aging and senotherapies have been discussed that show promising results for future interventions.

WIDER IMPLICATIONS

In most countries of the Organization for Economic Co-operation and Development, the average age at which women give birth is above 30 years. Currently, in countries such as the Netherlands, Australia, Spain, Finland, Germany and the UK, birth rates among 30- to 34-year-olds are now higher than in any other age groups. This review will provide new knowledge and scientific advancement on the senescence mechanisms during female reproductive aging, and benefit fundamental and clinical scientists and professionals in the areas of reproduction, cancer, immunobiology and fibrosis.

Racial disparities in frozen embryo transfer success

PURPOSE

To compare pregnancy and birth outcomes after frozen embryo transfers (FETs) among White, Black, and Asian women and evaluate the effect of patient, protocol, and cycle characteristics on success.

METHODS

A retrospective chart review identified women who underwent an autologous FET at an academic fertility center between January 2013 and March 2020.

RESULTS

White, Black, and Asian women completed 1,181 (71.7%), 230 (14.0%), and 235 (14.3%) cycles, respectively. Black women were significantly less likely to achieve a positive hCG level (AOR 0.66, 95% CI 0.49-0.90), clinical pregnancy (AOR 0.71, 95% CI 0.53-0.97), and live birth (AOR 0.65, 95% CI 0.47-0.89) compared to White women after adjusting for possible confounders. There were no differences in the aforementioned outcomes when looking at cycles completed by Asian versus White women. When comparing outcomes by endometrial preparation protocol, significant differences were seen amongst the three groups for live birth rates following natural cycle FETs (52.36%, 25.81%, and 44.19% for White, Black, and Asian women, respectively, p = 0.02), a difference not appreciated after programmed FETs.

CONCLUSION

Black race is associated with significantly worse pregnancy and live birth rates following FET when compared to White race. Additionally, significant differences in live birth rates among White, Black, and Asian women exist following natural cycle FET versus programmed FET. These disparities in success are not only important for patient counseling, but also when determining management strategies to improve fertility rates among minority women.

Quercetin effect on the efficiency of ovine oocyte vitrification at GV stage

The widely adopted method of vitrification is known to induce some negative effects on oocytes. In order to enhance the efficiency of this process performed on ovine oocytes at germinal vesicle stage, vitrification and warming (VW) solutions, and maturation media were supplemented with 5 μM Quercetin (Q). Four groups of vitrified and fresh immature oocytes were subjected to IVM, IVF and IVC, and their survival rate, apoptosis, nuclear status and developmental competence were assessed. Non-vitrified oocytes treated with Quercetin experienced higher cleavage rate relative to those matured without Quercetin (p < 0.05). Supplementation of VW and maturation media with Quercetin resulted in increased survival, cleavage and total blastocyst rates relative to the untreated oocytes. The post-IVM survival rate of non-vitrified oocytes showed no difference among those matured with and without Quercetin, but was higher for oocytes vitrified, warmed and matured with Quercetin relative to VW group lacking Quercetin. The proportion of early-apoptotic (AV+) oocytes was affected by Quercetin supplementation in both control and VW groups (p < 0.05). The number of AV positive oocytes was lower and the proportion of oocytes reaching MII stage was greater in non-vitrified and VW groups matured with Quercetin, in comparison with their untreated respective controls (p < 0.05). There was no difference in the number of late-stage apoptotic oocytes among different groups. It is concluded that supplementing vitrification and warming solutions with Quercetin endows vitrified ovine oocytes with protective potential against early apoptotic damage, and improves viability, maturation rate and developmental competence at GV stage.

Protective effects of dichloroacetic acid on endometrial injury and ovarian reserve in an experimental rat model of diabetes mellitus

AIM

To study (1) ovarian and endometrial damage caused by the hyperglycemia and (2) the effects of dichloroacetic acid (DCA) on follicular reserve and endometrial damage in streptozocin induced diabetic rats.

METHODS

This study consisted 24 rats randomly separated into three groups. A diabetes model was achieved in 16 rats experimentally, and normoglycemic eight rats were assigned as control group (Group 1). The rats with diabetes were randomly separated to two groups: 1 mL/kg/day intraperitoneal 0.9% NaCl was given to eight rats as diabetic vehicle (Group 2) and 10 mg/kg/day DCA was given to other eight rats as DCA treated group (Group 3). Hysterectomy with bilateral oophorectomy was performed for histopathological evaluation and blood samples were collected after 4 weeks.

RESULTS

Diabetes caused ovarian and endometrial damage (p < 0.0001). Pentraxin-3 (PTX-3), lactic acid, and transforming growth factor-beta (TGF-β) were higher (p < 0.05, p < 0.05, and p < 0.0001, respectively), whereas anti-Mullerian hormone (AMH) was lower in diabetic rats (p < 0.05). These findings reflected the diabetic damage in the genital tract and diminished ovarian reserve occurred via fibrosis, severe inflammation, and oxidative stress. DCA improved the histopathological fibrosis and degeneration in the ovaries and endometrium (p < 0.05). There was a concominant decrease of TGF-β and lactic acid levels with DCA treatment (p < 0.05). DCA also improved ovarian reserve with higher AMH levels (p < 0.05).

CONCLUSIONS

The several unfavored changes in the endometrium and ovaries due to diabetes have been determined in this present study. DCA might provide the continuity of the endometrial cycle, physiological endometrial structure, ovarian follicular growth, oocyte maturation, and physiological ovarian function by decreasing the lactate levels via inhibiting pyruvate dehydrogenase kinase enzyme.

Trapa bispinosa Roxb. extract lowers advanced glycation end-products and increases live births in older patients with assisted reproductive technology: a randomized controlled trial

BACKGROUND

Advanced glycation end-products (AGE), which accumulate with insulin resistance and aging, impair folliculogenesis and may decrease endometrial receptivity. Hishi (Trapa bispinosa Roxb.) extract, a safe herbal medicine, strongly inhibits AGE formation in vitro. We determined whether Hishi lowers AGE and increases live births in older assisted reproductive technology (ART) patients.

METHODS

This prospective randomized open-label controlled trial included 64 patients 38 to 42 years old undergoing ART with or without Hishi extract between June 11, 2015 and July 12, 2019. None had over 2 ART failures, diabetes, uterine anomalies, or exhausted ovarian reserve. After allocation, the Hishi group received Hishi extract (100 mg/day) until late pregnancy or failure. The control group received no extract. Both groups underwent 1 cycle of conventional infertility treatment; 1 long-protocol cycle of ovarian stimulation, oocyte retrieval, in vitro fertilization/intracytoplasmic sperm injection, and fresh embryo transfer (ET); and, if needed, cryopreserved ET until live birth or embryo depletion. Serum AGE were measured before and during ART, as were AGE in follicular fluid (FF).

RESULTS

Cumulative live birth rate among 32 Hishi patients was 47%, significantly higher than 16% among 31 controls (p<0.01; RR, 4.6; 95% CI, 1.4 - 15.0; 1 control dropped out). Live birth rate per ET, including fresh and cryopreserved, was significantly higher with Hishi (28% in 47 ET vs. 10% in 49 ET; p<0.05; RR, 3.4; 95% CI, 1.1-10.4). Among variables including age, day-3 FSH, anti-Müllerian hormone, and Hishi, logistic regression identified only Hishi as significantly associated with increased cumulative live birth (p<0.05; OR, 5.1; 95% CI, 1.4 - 18.3). Hishi significantly enhanced oocyte developmental potential, improved endometrial receptivity in natural cycles, and decreased AGE in serum and FF. Larger serum AGE decreases with Hishi were associated with more oocytes becoming day-2 embryos.

CONCLUSIONS

Hishi decreased AGE in serum and FF and improved oocyte developmental potential and endometrial receptivity, increasing live births in older patients. Treatment of infertility by AGE reduction represents a new addition to infertility treatment. Therapeutic trials of Hishi for other AGE-associated diseases might be considered.

TRIAL REGISTRATION

UMIN registration in Japan ( UMIN000017758 ) on June 1, 2015. https://www.umin.ac.jp/ctr/index.htm.

Do follicular fluid advanced glycation end products levels affect the ovarian response in unexplained infertility?

OBJECTIVE

To compare the advanced glycation end products (AGEs) levels in follicular fluid according to the different ovarian responses of women who underwent controlled ovarian stimulation due to unexplained infertility and to examine the relationship between these levels and pregnancy outcomes.

METHODS

Sixty-three women who underwent fresh IVF/ICSI cycles with GNRH antagonist protocol were divided into 3 groups according to the number of retrieved oocytes as suboptimal (4-9 oocytes), optimal (10-15 oocytes) and high (>15 oocytes) responders. AGEs levels in follicular fluid were measured by ELISA method.

RESULTS

AGEs levels were 6.81 ± 2.20 µg/ml, 5.30 ± 2.01 and 6.44 ± 1.43 µg/ml in suboptimal, optimal and high response group, respectively. AGEs level was significantly higher in suboptimal response group than in optimal response group. The cutoff level of 6.19 µg/ml had a sensitivity of 59.3% and a specificity of 66.7% in distinguishing the suboptimal response group from the optimal response group. However, there were no statistically significant difference between AGEs levels and clinical pregnancy and live birth rates.

CONCLUSION

Increased AGEs level in follicular fluid may be associated with decreased ovarian response during controlled ovarian stimulation in unexplained infertility case, however, it does not provide information about pregnancy outcomes.

The m6A mRNA demethylase FTO in granulosa cells retards FOS-dependent ovarian aging

Multifunctional N6-methyladenosine (m6A) has been revealed to be an important epigenetic component in various physiological and pathological processes, but its role in female ovarian aging remains unclear. Thus, we demonstrated m6A demethylase FTO downregulation and the ensuing increased m6A in granulosa cells (GCs) of human aged ovaries, while FTO-knockdown GCs showed faster aging-related phenotypes mediated. Using the m6A-RNA-sequence technique (m6A-seq), increased m6A was found in the FOS-mRNA-3'UTR, which is suggested to be an erasing target of FTO that slows the degradation of FOS-mRNA to upregulate FOS expression in GCs, eventually resulting in GC-mediated ovarian aging. FTO acts as a senescence-retarding protein via m6A, and FOS knockdown significantly alleviates the aging of FTO-knockdown GCs. Altogether, the abovementioned results indicate that FTO in GCs retards FOS-dependent ovarian aging, which is a potential diagnostic and therapeutic target against ovarian aging and age-related reproductive diseases.

Modulation of Intracellular ROS and Senescence-Associated Phenotypes of Xenopus Oocytes and Eggs by Selective Antioxidants

Aging of oocytes and eggs diminishes their reproductive and developmental potential. It has been demonstrated previously that reactive oxygen species (ROS) contribute to accelerated aging of various cells. In the present study, we measured intracellular levels of ROS and investigated effects of several selective antioxidants (AOXs) on the viability and functional activity of aging oocytes and eggs of the African clawed frog Xenopus laevis. The fluorescent cell-permeable dye DCFDA, which is widely employed for ROS detection in cultured mammalian cells, was used to monitor ROS levels in the fresh and bench-aged oocytes and eggs by an optimized protocol. It was found that intracellular ROS contents were increased in frog oocytes and eggs aged for 48 h. It was further demonstrated using selective cell-permeable AOXs targeting different ROS-generating mechanisms, that the major source of ROS in Xenopus oocytes and eggs is the plasma membrane NADPH oxidase, and that mitochondrial generation contributes to the intracellular ROS content to a lesser extent. Targeted inhibition of NADPH oxidase with a natural organic compound apocynin reduced ROS levels significantly in Xenopus oocytes and eggs, maintained their normal phenotype and supported their functional competence. To our knowledge this is the first report concerning beneficial effects of apocynin on the isolated gamete cells, such as oocytes and eggs.

Are the body shape index, the body roundness index and waist-to-hip ratio better than BMI to predict recurrent pregnancy loss?

PURPOSE

Etiology could not be determined in approximately 50% of recurrent pregnancy loss cases, and it was named unexpected recurrent pregnancy loss(URPL). A body shape index(ABSI), body roundness index(BRI), and waist-to-hip ratio(WtHR) are new indexes that are superior to BMI in showing body fat distribution. We aimed to investigate the potency of ABSI, BRI, and WtHR in URPL, their superiority to BMI, and their suitability for clinical use.

METHODS

One hundred and thirty-eight patients between the ages of 20-40 who applied to our hospital for URPL between January 2016 and December 31, 2020 were included in our study. Weight, height, waist circumference, and hip circumference were measured, and indexes were calculated. Differences between the URPL and control groups were calculated using the IBM SPSS program.

RESULTS

There was a significant difference between the two groups for BRI, ABSI, and WtHR values, while there was no significant difference in BMI. BRI(4.4 ± 1.7vs3.9 ± 1.5), ABSI(0.08 ± 0.005 vs 0.078 ± 0.004), and WtHR(0.84 ± 0.06vs0.82 ± 0.05) values were higher in the URPL group. ROC analysis showed us that BRI, ABSI, and WtHR have a diagnostic value for URPL(P < .05). When indexes were above the cutoff values, RPL risk increased 3.59 times in ABSI, 2.26 times in BRI, and 2.9 times in WtHR(P < .05).

CONCLUSIONS

The relationship between obesity and URPL can be explained more clearly by using effective indexes that show body fat distribution rather than BMI. Ethics committee approval was obtained from Erzincan Binali Yildirim University in 14.01.2021. Clinical Research Ethics Committee no: 01/01.

Subchronic and Low Dose of Tributyltin Exposure Leads to Reduced Ovarian Reserve, Reduced Uterine Gland Number, and Other Reproductive Irregularities in Female Mice

Tributyltin (TBT) chloride is an endocrine disrupting chemical associated with reproductive complications. Studies have shown that TBT targets the reproductive tract, impairing ovarian folliculogenesis, and uterine morphophysiology. In this investigation, we assessed whether subchronic and low dose of TBT exposure results in abnormal ovarian follicular reserve and other irregularities in female mice. TBT was administered to female mice (500 ng/kg/day for 12 days via gavage), and reproductive tract morphophysiology was assessed. We further assessed reproductive tract inflammation and oxidative stress. Improper functioning of the reproductive tract in TBT mice was observed. Specifically, irregular estrous cyclicity and abnormal ovarian morphology coupled with reduction in primordial and primary follicle numbers was observed, suggesting ovarian reserve depletion. In addition, improper follicular development and a reduction in antral follicles, corpora lutea, and total healthy ovarian follicles together with an increase in cystic follicles were apparent. Evidence of uterine atrophy, reduction in endometrial gland number, and inflammation and oxidative stress were seen in TBT mice. Further, strong negative correlations were observed between testosterone levels and primordial, primary, and total healthy ovarian follicles. Thus, these data suggest that the subchronic and low dose of TBT exposure impaired ovarian follicular reserve, uterine gland number, and other reproductive features in female mice.

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.

Female ageing affects the DNA repair capacity of oocytes in IVF using a controlled model of sperm DNA damage in mice

STUDY QUESTION

Does female ageing have a negative effect on the DNA repair capacity of oocytes fertilised by spermatozoa with controlled levels of DNA damage?

SUMMARY ANSWER

Compared to oocytes from younger females, oocytes from older females have a reduced capacity to repair damaged DNA introduced by spermatozoa.

WHAT IS KNOWN ALREADY

The reproductive lifespan in women declines with age predominantly due to poor oocyte quality. This leads to decreased reproductive outcomes for older women undergoing assisted reproductive technology (ART) treatments, compared to young women. Ageing and oocyte quality have been clearly associated with aneuploidy, but the range of factors that influence this change in oocyte quality with age remains unclear. The DNA repair activity prior to embryonic genomic activation is considered to be of maternal origin, with maternal transcripts and proteins controlling DNA integrity. With increasing maternal age, the number of mRNAs stored in oocytes decreases. This could result in diminished efficiency of DNA repair and/or negative effects on embryo development, especially in the presence of DNA damage.

STUDY DESIGN, SIZE, DURATION

Oocytes from two age groups of 30 super-ovulated female mice (young: 5-8 weeks old, n = 15; old: 42-45 weeks old, n = 15) were inseminated with sperm from five males with three different controlled DNA damage levels; control: ≤10%, 1 Gray (Gy): 11-30%, and 30 Gy: >30%. Inseminated oocytes (young: 125, old: 78) were assessed for the formation of zygotes (per oocyte) and blastocysts (per zygote). Five replicates of five germinal vesicles (GVs) and five MII oocytes from each age group were analysed for gene expression. The DNA damage response (DDR) was assessed in a minimum of three IVF replicates in control and 1 Gy zygotes and two-cell embryos using γH2AX labelling.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Swim-up sperm samples from the cauda epididymidis of C57BL6 mice were divided into control (no irradiation) and 1- and 30-Gy groups. Treated spermatozoa were irradiated at 1 and 30 Gy, respectively, using a linear accelerator Varian 21iX. Following irradiation, samples were used for DNA damage assessment (Halomax) and for insemination. Presumed zygotes were cultured in a time-lapse incubator (MIRI, ESCO). Gene expression of 91 DNA repair genes was assessed using the Fluidigm Biomark HD system. The DNA damage response in zygotes (6-8 h post-fertilisation) and two-cell embryos (22-24 h post-fertilisation) was assessed by immunocytochemical analysis of γH2AX using confocal microscopy (Olympus FV1200) and 3D volumetric analysis using IMARIS software.

MAIN RESULTS AND THE ROLE OF CHANCE

The average sperm DNA damage for the three groups was statistically different (control: 6.1%, 1 Gy: 16.1%, 30 Gy: 53.1%, P < 0.0001), but there were no significant differences in fertilisation rates after IVF within or between the two age groups [(young; control: 86.79%, 1 Gy: 82.75%, 30 Gy: 76.74%) (old; control: 93.1%, 1 Gy: 70.37%, 30 Gy: 68.18%) Fisher's exact]. However, blastocyst rates were significantly different (P < 0.0001) among the groups [(young; control: 86.95%, 1 Gy: 33.33%, 30 Gy: 0.0%) (old; control: 70.37%, 1 Gy: 0.0%, 30 Gy: 0.0%)]. Between the age groups, 1-Gy samples showed a significant decrease in the blastocyst rate in old females compared to young females (P = 0.0166). Gene expression analysis revealed a decrease in relative expression of 21 DNA repair genes in old GV oocytes compared to young GV oocytes (P < 0.05), and similarly, old MII oocytes showed 23 genes with reduced expression compared to young MII oocytes (P < 0.05). The number of genes with decreased expression in older GV and MII oocytes significantly affected pathways such as double strand break (GV: 5; MII: 6), nucleotide excision repair (GV: 8; MII: 5) and DNA damage response (GV: 4; MII: 8). There was a decreased DDR in zygotes and in two-cell embryos from old females compared to young regardless of sperm treatment (P < 0.05). The decrease in DNA repair gene expression of oocytes and decreased DDR in embryos derived from older females suggests that ageing results in a diminished DNA repair capacity.

LARGE-SCALE DATA

N/A.

LIMITATIONS, REASONS FOR CAUTION

Ionising radiation was used only for experimental purposes, aiming at controlled levels of sperm DNA damage; however, it can also damage spermatozoa proteins. The female age groups selected in mice were intended to model effects in young and old women, but clinical studies are required to demonstrate a similar effect.

WIDER IMPLICATIONS OF THE FINDINGS

Fertilisation can occur with sperm populations with medium and high DNA damage, but subsequent embryo growth is affected to a greater extent with aging females, supporting the theory that oocyte DNA repair capacity decreases with age. Assessment of the oocyte DNA repair capacity may be a useful diagnostic tool for infertile couples.

STUDY FUNDING/COMPETING INTEREST(S)

Funded by the Education Program in Reproduction and Development, Department of Obstetrics and Gynaecology, Monash University. None of the authors has any conflict of interest to report.

DNA repair in primordial follicle oocytes following cisplatin treatment

PURPOSE

Genotoxic chemotherapy and radiotherapy can cause DNA double stranded breaks (DSBs) in primordial follicle (PMF) oocytes, which then undergo apoptosis. The development of effective new fertility preservation agents has been hampered, in part, by a limited understanding of DNA repair in PMF oocytes. This study investigated the induction of classical DSB repair pathways in the follicles of wild type (WT) and apoptosis-deficient Puma^-/- mice in response to DSBs caused by the chemotherapy agent cisplatin.

METHODS

Adult C57BL/6 WT and Puma^-/- mice were injected i.p. with saline or cisplatin (5 mg/kg); ovaries were harvested at 8 or 24 h. Follicles were counted, and H2A histone family member (γH2AX) immunofluorescence used to demonstrate DSBs. DNA repair protein RAD51 homolog 1 (RAD51) and DNA-dependent protein kinase, catalytic subunit (DNA-PKcs) immunofluorescence were used to identify DNA repair pathways utilised.

RESULTS

Puma^-/- mice retained 100% of follicles 24 h after cisplatin treatment. Eight hours post-treatment, γH2AX immunofluorescence showed DSBs across follicular stages in Puma^-/- mice; staining returned to control levels in PMFs within 5 days, suggesting repair of PMF oocytes in this window. RAD51 immunofluorescence eight hours post-cisplatin was positive in damaged cell types in both WT and Puma^-/- mice, demonstrating induction of the homologous recombination pathway. In contrast, DNA-PKcs staining were rarely observed in PMFs, indicating non-homologous end joining plays an insignificant role.

CONCLUSION

PMF oocytes are able to conduct high-fidelity repair of DNA damage accumulated during chemotherapy. Therefore, apoptosis inhibition presents a viable strategy for fertility preservation in women undergoing treatment.

Morroniside suppresses hydrogen peroxide-stimulated autophagy and apoptosis in rat ovarian granulosa cells through the PI3K/AKT/mTOR pathway

Previous evidences have indicated that granulosa cells play a critical role in follicular growth. Hydrogen peroxide (H2O2)-induced oxidative stress has been associated with ovarian granulosa cell apoptosis and ovarian function. Recently, a study highlighted the protective role of morroniside against H2O2-induced damage. In this study, we aimed to investigate the effects of morroniside on H2O2-stimulated rat ovarian granulosa cells and its underlying molecular mechanisms. Our results showed that H2O2 treatment suppressed cell survival and increased apoptosis in rat granulosa cells, while treatment with morroniside markedly increased H2O2-induced granulosa cell survival in a dose-dependent manner (0, 10, 50 and 100 µM). Moreover, treatment with 50 µM morroniside impeded H2O2-induced cell apoptosis. An elevation in intracellular ROS, MDA, SOD, GSH-Px, and CAT level was observed in H2O2-induced granulosa cells; however, this effect was abrogated by morroniside treatment. Further studies suggested that administration of morroniside inhibited H2O2-induced granulosa cell apoptosis and caspase-3 activity. In addition, after morroniside treatment of H2O2-stimulated granulosa cells, autophagy-related protein (LC3-II/LC3-I ratio) and beclin-1 expression was decreased and p62 level was increased. Interestingly, we found that morroniside treatment activated the PI3K/AKT/mTOR pathway in H2O2-stimulated granulosa cells. Finally, we showed that treatment with PI3K and mTOR inhibitors reversed the protective effects of morroniside on H2O2-induced granulosa cells. Taken together, our data suggest that treatment with morroniside decreased apoptosis, autophagy, and oxidative stress in rat granulosa cells through the PI3K/AKT/mTOR pathway.

Tet1 Deficiency Leads to Premature Ovarian Failure

Tet enzymes participate in DNA demethylation and play critical roles in stem cell pluripotency and differentiation. DNA methylation alters with age. We find that Tet1 deficiency reduces fertility and leads to accelerated reproductive failure with age. Noticeably, Tet1-deficient mice at young age exhibit dramatically reduced follicle reserve and the follicle reserve further decreases with age, phenomenon consistent with premature ovarian failure (POF) syndrome. Consequently, Tet1-deficient mice become infertile by reproductive middle age, while age matched wild-type mice still robustly reproduce. Moreover, by single cell transcriptome analysis of oocytes, Tet1 deficiency elevates organelle fission, associated with defects in ubiquitination and declined autophagy, and also upregulates signaling pathways for Alzheimer's diseases, but down-regulates X-chromosome linked genes, such as Fmr1, which is known to be implicated in POF. Additionally, Line1 is aberrantly upregulated and endogenous retroviruses also are altered in Tet1-deficient oocytes. These molecular changes are consistent with oocyte senescence and follicle atresia and depletion found in premature ovarian failure or insufficiency. Our data suggest that Tet1 enzyme plays roles in maintaining oocyte quality as well as oocyte number and follicle reserve and its deficiency can lead to POF.

Causal Effects of Body Mass Index and Maternal Age on Oocyte Maturation in Assisted Reproductive Technology: Model-Average Causal Effect and Bayesian LASSO Method

Background:

Body Mass Index (BMI) and maternal age are related to various disorders of the female reproductive system. This study aimed to estimate the causal effects of BMI and maternal age on the rate of meta-phase II oocytes (MII) using a new statistical method based on Bayesian LASSO and model averaging.

Methods:

This investigation was a historical cohort study and data were collected from women who underwent assisted reproductive treatments in Tehran, Iran during 2015 to 2018. Exclusion criteria were gestational surrogacy and donor oocyte. We used a new method based on Bayesian LASSO and model average to capture important confounders.

Results:

Overall, 536 cycles of 398 women were evaluated. BMI and Age had inverse relationships with the number of MII based on univariate analysis, but after adjusting the effects of other variables, there was just a significant association between age and the number of MII (adjusted incidence rate ratio (aIRR) of age =0.989, 95% CI: [0.979, 0.998], P=0.02). The results of causal inference based on the new presented method showed that the overall effects of age and BMI of all patients were significantly and inversely associated with the number of MII (both P<0.001). Therefore the expected number of MII decreased by 0.99 for an increase of 1 year (95% CI: [−1.00, −0.97]) and decreased by 0.99 for each 1-unit increase in BMI (95% CI: [−1.01, −0.98]).

Conclusion:

Maternal age and BMI have significant adverse casual effects on the rate of MII in patients undergoing ART when the effects of important confounders were adjusted.

Heterogeneity and Dynamics of Vasculature in the Endocrine System During Aging and Disease

The endocrine system consists of several highly vascularized glands that produce and secrete hormones to maintain body homeostasis and regulate a range of bodily functions and processes, including growth, metabolism and development. The dense and highly vascularized capillary network functions as the main transport system for hormones and regulatory factors to enable efficient endocrine function. The specialized capillary types provide the microenvironments to support stem and progenitor cells, by regulating their survival, maintenance and differentiation. Moreover, the vasculature interacts with endocrine cells supporting their endocrine function. However, the structure and niche function of vasculature in endocrine tissues remain poorly understood. Aging and endocrine disorders are associated with vascular perturbations. Understanding the cellular and molecular cues driving the disease, and age-related vascular perturbations hold potential to manage or even treat endocrine disorders and comorbidities associated with aging. This review aims to describe the structure and niche functions of the vasculature in various endocrine glands and define the vascular changes in aging and endocrine disorders.

Hypothalamic aging and hormones

It is the heterogeneous changes of hypothalamic functions that determine the chronological sequence of aging in mammals. Recently, it was hypothesized by Cai the decrease in slow-wave sleep (SWS) resulting from skin aging as responsible for the degeneration of hypothalamic suprachiasmatic nucleus (SCN). It was soon hypothesized by the European people in television that the increase in body fat as responsible for the degeneration of male preoptic sexually dimorphic nucleus (SDN-POA), via the aromatase converting testosterone to estradiol as proposed by Cohen. It is the hypothalamic paraventricular nucleus (PVN) that remains unchanged in neuron number during aging for psychological stress. In this chapter, it is briefly reviewed more manifestations of hypothalamic related mammalian aging processes, including (1) the aging of ovary by lipid, estradiol and hypothalamus; (2) the aging of muscle, stomach, intestine, thymus, and the later aging of brain, regulated by growth hormone/insulin-like growth factor 1(GH/IGF1); (3) the cardiovascular hypertension from PVN activation, the bone and other peripheral aging by psychological stress, and that of kidney by vasopressin. It is classified these aging processes by the primary regulation from one of the three hypothalamic nuclei, although still necessary to investigate and supplement their secondary regulation by the hypothalamic nuclei in future. It is the hypothalamic structural changes that shift the functional balance among these three hypothalamic systems toward aging.

The clinical outcomes of fresh versus frozen embryos transfer in women ≥40 years with poor ovarian response

Objective

To compare the clinical outcomes of fresh embryo transfers (ETs) and frozen-thawed embryo transfers (FETs) after a freeze-all cycle in women ≥40 years old with poor ovarian response (POR).

Methods

We performed a single-center, retrospective, case-control study of patients who underwent in vitro fertilization between January 2014 and June 2019. We included a total of 192 patients aged 40 years or older from whom 3 or fewer oocytes had been retrieved and who were receiving cleavage-stage ET in this study. Of these patients, 101 and 91 patients underwent fresh ET and FET, respectively. The primary outcome was the live birth rate (LBR) after the first ET. Logistic regression analysis was used to compare the IVF outcomes and neonatal characteristics between the fresh ET and FET groups, adjusting for maternal age, body mass index, luteinizing hormone, and the number of good quality embryos transferred.

Results

The mean maternal ages and number of oocytes retrieved (43.2 years and 2.3 in both groups, P=0.902 and P=0.927, respectively) were similar in the fresh ET and FET groups. No significant difference was observed between the LBRs of the fresh ET and FET groups (adjusted odds ratio, 1.28; 95% confidence interval, 0.29–5.70). The clinical pregnancy and miscarriage rates, and neonatal characteristics (birth weights and premature infant rates) were similar between the 2 groups.

Conclusions

FET after the freeze-all strategy had no beneficial impact on the clinical outcomes of women ≥40 years with POR.

MicroRNA-Mediated Gene Regulatory Mechanisms in Mammalian Female Reproductive Health

Mammalian reproductive health affects the entire reproductive cycle starting with the ovarian function through implantation and fetal growth. Various environmental and physiological factors contribute to disturbed reproductive health status leading to infertility problems in mammalian species. In the last couple of decades a significant number of studies have been conducted to investigate the transcriptome of reproductive tissues and organs in relation to the various reproductive health issues including endometritis, polycystic ovarian syndrome (PCOS), intrauterine growth restriction (IUGR), preeclampsia, and various age-associated reproductive disorders. Among others, the post-transcriptional regulation of genes by small noncoding miRNAs contributes to the observed transcriptome dysregulation associated with reproductive pathophysiological conditions. MicroRNAs as a class of non-coding RNAs are also known to be involved in various pathophysiological conditions either in cellular cytoplasm or they can be released to the extracellular fluid via membrane-bounded extracellular vesicles and proteins. The present review summarizes the cellular and extracellular miRNAs and their association with the etiology of major reproductive pathologies including PCOS, endometritis, IUGR and age-associated disorders in various mammalian species.

Subacute cadmium exposure disrupts the hypothalamic-pituitary-gonadal axis, leading to polycystic ovarian syndrome and premature ovarian failure features in female rats

Cadmium (Cd), a toxic heavy metal, is a known endocrine disruptor that is associated with reproductive complications. However, few studies have explored the effects of Cd exposure on features of polycystic ovary syndrome (PCOS) and premature ovary failure (POF). In this study, we assessed whether doses found in workers occupationally exposed to Cd and subacute exposure result in hypothalamic-pituitary-gonadal (HPG) axis and other irregularities. We administered CdCl₂ to female rats (100 ppm in drinking water for 30 days) and then assessed Cd levels in the blood, HPG axis and uterus. Metabolic features, HPG axis function, reproductive tract (RT) morphophysiology, inflammation, oxidative stress (OS), and fibrosis were evaluated. Cd exposure increased Cd levels in the serum, HPG axis, and uterus. Cd rats displayed metabolic impairments, such as a reduction in adiposity, dyslipidemia, and insulin resistance (IR). Cd exposure also caused improper functioning in the HPG. Specifically, Cd exposure caused irregular estrous cyclicity, abnormal hypothalamic gene expression (upregulated - Kiss1, AR and mTOR; downregulated - Kiss1R, LepR and TNF-α), high LH levels, low AMH levels and abnormal ovarian follicular development, coupled with a reduction in ovarian reserve and antral follicle number was observed, suggesting ovarian depletion. Further, Cd exposure caused a reduction in corpora lutea (CL) and granulosa layer thickness together with an increase in cystic/atretic follicles. In addition, Cd exposure caused RT inflammation, OS and fibrosis. Finally, strong positive correlations were observed between serum, RT Cd levels, IR, dyslipidemia and estrous cycle length, cystic, atretic follicles, LH levels, and RT inflammation. Thus, these data suggest that subacute Cd exposure using doses found in workers occupationally exposed to Cd disrupt the HPG axis function, leading to PCOS and POF features and other abnormalities in female rats.

The antioxidant curcumin postpones ovarian aging in young and middle-aged mice

Reproductive senescence is accompanied by a reduced number and quality of ovarian follicles in response to the accumulation of free radicals and the process of apoptosis. Having selected mice as models, we examined the hypothesis that curcumin as an antioxidant and anti-inflammatory agent might prevent or retard ovarian aging. Female NMRI 21-day-old mice were divided into control, vehicle and curcumin groups. In the treatment group the mice received curcumin at 100mgkg-1day-1 intraperitoneally. After 6, 12 and 33 weeks several parameters were examined including ovarian reserve, oocyte quality, oxidative status, invitro fertilisation and expression of ovulation-related (growth differentiation factor 9 (GDF-9) and bone morphogenetic protein 15 (BMP-15)) and anti-aging-related (sirtuin 1 (SIRT-1) and SIRT-3) genes. Curcumin treatment up to 12 and 33 weeks resulted in increased ovarian volume and number of follicles and was associated with elevated anti-Müllerian hormone and oestrogen and diminished FSH serum levels. Furthermore, enhanced oocyte maturation, fertilisation and embryo development plus reduced oxidative stress were seen in the curcumin group. Also, the expression of GDF-9, BMP-15, SIRT-1 and SIRT-3 genes was increased in the curcumin group. Concerning gestational age, the findings of the study suggested that administration of curcumin could delay the process of oocyte aging in a mouse model.

Multifactor Prediction of Embryo Transfer Outcomes Based on a Machine Learning Algorithm

In vitro fertilization-embryo transfer (IVF-ET) technology make it possible for infertile couples to conceive a baby successfully. Nevertheless, IVF-ET does not guarantee success. Frozen embryo transfer (FET) is an important supplement to IVF-ET. Many factors are correlated with the outcome of FET which is unpredictable. Machine learning is a field of study that predict various outcomes by defining data attributes and using relevant data and calculation algorithms. Machine learning algorithm has been widely used in clinical research. The present study focuses on making predictions of early pregnancy outcomes in FET through clinical characters, including age, body mass index (BMI), endometrial thickness (EMT) on the day of progesterone treatment, good-quality embryo rate (GQR), and type of infertility (primary or secondary), serum estradiol level (E2) on the day of embryo transfer, and serum progesterone level (P) on the day of embryo transfer. We applied four representative machine learning algorithms, including logistic regression (LR), conditional inference tree, random forest (RF) and support vector machine (SVM) to build prediction models and identify the predictive factors. We found no significant difference among the models in the sensitivity, specificity, positive predictive rate, negative predictive rate or accuracy in predicting the pregnancy outcome of FET. For example, the positive/negative predictive rate of the SVM (gamma = 1, cost = 100, 10-fold cross validation) is 0.56 and 0.55. This approach could provide a reference for couples considering FET. The prediction accuracy of the present study is limited, which suggests that there may be some other more effective predictors to be developed in future work.

Ageing and ovarian stimulation modulate the relative levels of transcript abundance of oocyte DNA repair genes during the germinal vesicle-metaphase II transition in mice

PURPOSE

Oocyte quality and reproductive outcome are negatively affected by advanced maternal age, ovarian stimulation and method of oocyte maturation during assisted reproduction; however, the mechanisms responsible for these associations are not fully understood. The aim of this study was to compare the effects of ageing, ovarian stimulation and in-vitro maturation on the relative levels of transcript abundance of genes associated with DNA repair during the transition of germinal vesicle (GV) to metaphase II (MII) stages of oocyte development.

METHODS

The relative levels of transcript abundance of 90 DNA repair-associated genes was compared in GV-stage and MII-stage oocytes from unstimulated and hormone-stimulated ovaries from young (5-8-week-old) and old (42-45-week-old) C57BL6 mice. Ovarian stimulation was conducted using pregnant mare serum gonadotropin (PMSG) or anti-inhibin serum (AIS). DNA damage response was quantified by immunolabeling of the phosphorylated histone variant H2AX (γH2AX).

RESULTS

The relative transcript abundance in DNA repair genes was significantly lower in MII oocytes compared to GV oocytes in young unstimulated and PMSG stimulated but was higher in AIS-stimulated mice. Interestingly, an increase in the relative level of transcript abundance of DNA repair genes was observed in MII oocytes from older mice in unstimulated, PMSG-stimulated and AIS-stimulated mice. Decreased γH2AX levels were found in both GV oocytes (82.9%) and MII oocytes (37.5%) during ageing in both ovarian stimulation types used (PMSG/AIS; p < 0.05).

CONCLUSIONS

In conclusion, DNA repair relative levels of transcript abundance are altered by maternal age and the method of ovarian stimulation during the GV-MII transition in oocytes.

Prenatal exposure to an environmentally relevant phthalate mixture accelerates biomarkers of reproductive aging in a multiple and transgenerational manner in female mice

Phthalates are known endocrine-disrupting chemicals that are found in many consumer products. Our laboratory previously developed a relevant phthalate mixture consisting of six phthalates and found that it disrupted female fertility in mice. However, it is unknown if prenatal exposure to phthalate mixtures can accelerate reproductive aging and if this occurs in multiple generations. Thus, we tested the hypothesis that prenatal exposure to a mixture of phthalates accelerates biomarkers of reproductive aging in multiple generations of female mice. Pregnant CD-1 mice were orally dosed with vehicle control or a phthalate mixture (20 μg/kg/day-500 mg/kg/day) daily from gestational day 10 to birth. Adult F1 females born to these dams were used to create the F2 and F3 generations by mating them with unexposed males. At 13 months, estrous cyclicity was monitored and ovaries and sera were collected for analysis. In the F1 generation, the mixture decreased testosterone and inhibin B levels, but increased follicle-stimulating hormone and luteinizing hormone levels compared to control. In the F2 generation, the phthalate mixture decreased the percent of antral follicles and testosterone hormone levels compared to control. In the F3 generation, prenatal exposure to the phthalate mixture increased ovarian weight, increased the time in metestrus/diestrus, altered follicle numbers, and decreased the levels of luteinizing hormone compared to control. Collectively, these data suggest that prenatal exposure to a phthalate mixture may accelerate several biomarkers of reproductive aging in a multi- and transgenerational manner in female mice.

Association of exosomal microRNAs in human ovarian follicular fluid with oocyte quality

The postponement of childbearing by women has led to an increase in infertility. The reproductive aging process leads to a decrease in both the quantity and quality of oocytes. The aim of this study was to investigate exosomal microRNAs in human ovarian follicular fluid and explore their potential association with oocyte quality. We collected ovarian follicle fluid from 68 patients and assigned the patients to A (superior oocyte quality) or B (poor oocyte quality) group according to their oocyte quality. Exosomal miRNAs were extracted, library constructed and sequenced using the Illumina HiSeq platform. Subsequently, we analyzed exosomal miRNA expression, predicted the miRNA target genes, and enriched Gene Ontology terms using GOSeq. Kyoto Encyclopedia of Genes and Genomes pathway analysis was performed using miRanda. A total of 47 miRNAs were found to be significantly differentially expressed between group A and group B (p < 0.05). Among nine differentially expressed miRNAs that were previously known, seven were upregulated in group B. In silico analysis indicated that several of these exosomal miRNAs were involved in pathways implicated in oocyte quality. Analysis of the expression of exosomal miRNAs in human ovarian follicular fluid showed that they were critical for maintaining oocyte quality. Our findings provide the basis for further investigations of the functions of exosomal miRNAs in the ovarian microenvironment and suggest that these exosomal miRNAs may be potential biomarkers for evaluating oocyte quality. The findings are potentially important to maintain oocyte quality in clinical settings.

Extracellular Vesicles as Mediators of Environmental and Metabolic Stress Coping Mechanisms During Mammalian Follicular Development

Extracellular vesicles are evolutionarily conserved nano-sized phospholipid membraned structures and released from virtually all types of cells into the extracellular space. Their ability to carry various molecular cargos (mRNA, miRNA, proteins, and lipids) from one cell to the other to exert functional impact on the target cells enables them to play a significant role in cell to cell communication during follicular development. As the molecular signals carried by extracellular vesicles reflect the physiological status of the cells of origin, they are expected to mediate any effect of environmental or metabolic stress on the follicualr cells and the growing oocyte. Recent studies have evidenced that reproductive cells exposed to various environmental stressors (heat and oxidative stress) released extracellular vesicles enriched with mRNA and miRNA associated with stress response mechanisms. Moreover, the metabolic status of post-calving cows could be well-reflected in the follicular extracellular vesicle's miRNA profile, which signified the potential role of extracellular cellular vesicle molecular signals in mediating the effect of metabolic stress on follicular and oocyte development. In the present review, the potential role of extracellular vesicles in mediating the effect of environmental and metabolic stress in various reproductive cells and oocytes are thoroughly discussed Moreover, considering the importance of extracellular vesicles in shuttling protective or rescuing molecular signals during stress, their potential usage as means of targeted delivery of molecules to mitigate the effect of stress on oocytes are addressed as the focus of future research.

Quercetin promotes in vitro maturation of oocytes from humans and aged mice

Maternal fertility declines irreversibly with aging, and advanced maternal age is mostly related to impaired oocyte quality. The flavonol compound quercetin is considered to be an anti-aging agent due to its cytoprotective actions as an antioxidant. However, its role and mechanisms on aged oocytes are unclear. In this study, the quercetin promotes in vitro maturation (IVM) and early embryonic development of oocytes from aged mice. It is extended these findings in human oocytes, showing that quercetin promotes the IVM rate by 19.6% and increases the blastocyst formation rate by 15.5% compared to untreated controls. The overall oocyte quality of aged mice is improved by quercetin treatment, assessed as spindle/chromosome morphology and cortical granule distribution. Mitochondria is the primary endogenous source of age-related oxidative stress, and an RNA-seq analysis of quercetin-treated oocytes reveals molecular insights including scavenged mitochondrial-ROS, reduced apoptosis, and improved autophagy. Further, this study demonstrates that quercetin reduces ROS via SIRT3-mediated acetylation of SOD2's K68 residue. Thus, beyond demonstrating that quercetin confers beneficial mitochondria-related impacts in aged oocytes, this study illustrates a potential strategy to prevent or delay oocyte aging and to improve success rates of assisted human reproductive technologies (ART).

Human placenta-derived mesenchymal stem cells stimulate ovarian function via miR-145 and bone morphogenetic protein signaling in aged rats

Background

Aging has detrimental effects on the ovary, such as a progressive reduction in fertility and decreased hormone production, that greatly reduce the quality of life of women. Thus, the current study was undertaken to investigate whether human placenta-derived mesenchymal stem cell (hPD-MSC) treatment can restore the decreases in folliculogenesis and ovarian function that occur with aging.

Methods

Acclimatized 52-week-old female SD rats were randomly divided into four groups: single hPD-MSC (5 × 10⁵) therapy, multiple (three times, 10-day intervals) hPD-MSC therapy, control (PBS), and non-treated groups. hPD-MSC therapy was conducted by tail vein injection into aged rats. The rats were sacrificed 1, 2, 3, and 5 weeks after the last injection. hPD-MSC tracking and follicle numbers were histologically confirmed. The serum levels of sex hormones and circulating miRNAs were detected by ELISA and qRT-PCR, respectively. TGF-β superfamily proteins and SMAD proteins in the ovary were detected by Western blot analysis.

Results

We observed that multiple transplantations of hPD-MSCs more effectively promoted primordial follicle activation and ovarian hormone (E₂ and AMH) production than a single injection. After hPD-MSC therapy, the levels of miR-21-5p, miR-132-3p, and miR-212-3p, miRNAs associated with the ovarian reserve, were increased in the serum. Moreover, miRNAs (miR-16-5p, miR-34a-5p, and miR-191-5p) with known adverse effects on folliculogenesis were markedly suppressed. Importantly, the level of miR-145-5p was reduced after single- or multiple-injection hPD-MSC therapy, and we confirmed that miR-145-5p targets Bmpr2 but not Tgfbr2. Interestingly, downregulation of miR-145-5p led to an increase in BMPR2, and activation of SMAD signaling concurrently increased primordial follicle development and the number of primary and antral follicles.

Conclusions

Our study verified that multiple intravenous injections of hPD-MSCs led to improved ovarian function via miR-145-5p and BMP-SMAD signaling and proposed the future therapeutic potential of hPD-MSCs to promote ovarian function in women at advanced age to improve their quality of life during climacterium.

Association between women's age and stage, morphology, and implantation of the competent blastocyst: a multicenter cohort study

OBJECTIVE

To study if the age of women undergoing assisted reproductive technology treatment associates with stage, morphology, and implantation of the competent blastocyst.

DESIGN

Multicenter historical cohort study based on exposure (age) and outcome data (blastocyst stage and morphology and initial human chorionic gonadotrophin [hCG] rise) from women undergoing single blastocyst transfer resulting in singleton pregnancy/birth.

SETTING

Sixteen private and university-based facilities.

PATIENT(S)

In this study, 7,246 women who, between 2014 and 2018, underwent controlled ovarian stimulation (COS) or frozen-thawed embryo transfer (FET) with a single blastocyst transfer resulting in singleton pregnancy were identified. Linking data to the Danish Medical Birth Registry resulted in a total of 4,842 women with a live birth being included.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

The competent blastocyst development stage (1-6), inner cell mass (A, B, C), trophectoderm (A, B, C), and initial serum hCG value.

RESULT(S)

Adjusted analysis of age and stage in COS treatments showed that for every 1-year increase in age there was a 5% reduced probability of the competent blastocyst assessed as being in a high stage at transfer. Comparison between hCG values in women 18-24 years and 25-29 years in both COS and FET showed significantly lower levels in the youngest women.

CONCLUSION(S)

The initial hCG rise was influenced by the age of the woman, with an identical pattern for hCG values in COS and FET treatments. In COS, the competent blastocyst had a reduced stage with increasing women's age.

Improvement of early developmental competence of postovulatory-aged oocytes using metaphase II spindle injection in mice

Purpose

Assisted reproductive technology (ART) is a widely applied fertility treatment. However, the developmental competence of aged oocytes from women of a late reproductive age is seriously reduced and the aged oocytes often fail in fertilization even when ART is used. To resolve this problem, we examined usefulness of a new method “the metaphase II spindle transfer (MESI)” as ART using mouse oocytes.

Methods

This work was composed of two experiments. First, 24 hours after collection, embryos from oocytes (1‐day‐old oocytes, called postovulatory‐aged oocytes), were observed, after intracytoplasmic sperm injection (ICSI), and it was found that they were not able to reach the blastocyst stage. Next, the metaphase II chromosome‐spindle complexes from 1‐day‐old oocytes were injected into cytoplasts from oocytes just collected, using piezo pulses to generate reconstructed oocytes. This procedure was named metaphase II spindle injection (MESI).

Results

After ICSI, embryos from the reconstructed oocytes (32/105), which contained the genes of 1‐day‐old oocytes, were able to develop into the blastocyst stage. The fragmentation rate after ICSI was 28.6%. Thus, the developmental competence of 1‐day‐old oocytes was improved by MESI.

Conclusions

The MESI method has the potential to improve the success rate of infertility treatments for women of a late reproductive age.

MicroRNA-181a promotes follicular granulosa cell apoptosis via sphingosine-1-phosphate receptor 1 expression downregulation†

Oxidative stress induces granulosa cell (GC) apoptosis and subsequent follicular atresia. Since our previous studies indicate that microRNA-181a (miR-181a) expression is increased in GCs undergoing apoptosis, the present study was designed to define the relationship between exposure to oxidative stressors in GCs and changes in miR-181a expression and function. To achieve this, we employed an H2O2-induced in vitro model and a 3-nitropropionic acid-induced in vivo model of ovarian oxidative stress. We demonstrated that in vitro miR-181a overexpression promoted GC apoptosis in a dose-dependent manner; sphingosine-1-phosphate (S1P) significantly reversed both H2O2-induced and miR-181a-induced apoptosis in GCs. Moreover, we identified sphingosine-1-phosphate receptor 1 (S1PR1), a critical receptor of S1P, as a novel target of miR-181a in GCs. MicroRNA-181a induced GC apoptosis by repressing S1PR1 expression in vitro. Importantly, increased miR-181a expression and decreased S1PR1 expression were detected in the in vivo ovarian oxidative stress model by Western blot analysis and immunohistochemistry. Furthermore, we found similar expression patterns of miR-181a and S1PR1 in GCs from patients with premature ovarian insufficiency. In conclusion, our results suggest that miR-181a directly suppresses expression of S1PR1, which has critical roles in mediating oxidative stress-induced GC apoptosis both in vitro and in vivo.

Characterization of the Age-Dependent Changes in Antioxidant Defenses and Protein's Sulfhydryl/Carbonyl Stress in Human Follicular Fluid

The oxidative stress, characterized by the imbalance between pro-oxidants and antioxidants molecules, seems to be involved in the pathogenesis of female subfertility. In particular, the presence of different markers of oxidative stress has been reported in human follicular fluid (FF) surrounding oocytes. Based on its distinctive composition and on the close proximity to the oocyte, FF creates a unique microenvironment having a direct impact on oocyte quality, implantation, and early embryo development. An imbalance in reactive oxygen species (ROS) production in ovarian follicular fluid may have a negative effect on these processes and, as a consequence, on female fertility. Therefore, the aim of this study was to evaluate the redox state of the FF through various methodological approaches. By means of 2D-electrophoresis we demonstrated that the main structural changes occurring in the proteins of the follicular fluid of normovulatory women were correlated to the age of the patients and to the antioxidant defenses present in the FF. Measurement of these parameters could have clinical relevance, since the assessment of the oxidative stress rate may be helpful in evaluating in vitro fertilization potential.

Growth hormone alleviates oxidative stress and improves the IVF outcomes of poor ovarian responders: a randomized controlled trial

BACKGROUND

Oxidative stress (OS), defined as an imbalance between excessive reactive oxygen species (ROS) and/or reactive nitrogen species (RNS) production and antioxidant insufficiency, has been suggested to be involved in the pathogenesis of poor ovarian response (POR). Growth hormone (GH) can reduce OS in some cell types. This study investigated whether GH can improve OS and the in vitro fertilization and embryo transfer (IVF-ET) outcomes of poor ovarian responders.

METHODS

This study enrolled 105 patients with POR and 58 patients without POR (controls) who were diagnosed according to the Bologna criteria and underwent conventional IVF-ET. Poor ovarian responders were randomly assigned to two groups: the POR-GH group, which received pretreatment with GH 4 IU/d on day 2 of the previous menstrual cycle before IVF until the trigger day, and the POR-C group, which received no pretreatment. OS markers in follicular fluid (FF), ROS levels in granulosa cells (GCs), and the IVF outcomes of the groups were compared.

RESULTS

Endometrial thickness on trigger day, the number of cleaved embryos, the number of higher-quality embryos, and the rates of embryo formation, higher-quality embryo formation, implantation and clinical pregnancy were significantly increased in the POR-GH group compared with the POR-C group (P < 0.05). Moreover, compared to those in the non-POR group, FF malondialdehyde (MDA), total oxidant status (TOS), oxidative stress index (OSI) and ROS levels in GCs were significantly higher, whereas superoxide dismutase (SOD) and the total antioxidant capacity (TAC) were significantly lower in the POR-C group (P < 0.05). Furthermore, compared with those in the POR-C group, the FF TAC was significantly increased in the POR-GH group, and TOS, OSI and intracellular ROS levels were significantly reduced (P < 0.05).

CONCLUSIONS

Pretreatment with GH alleviates OS and improves oocyte quality and IVF outcomes of poor ovarian responders.

TRIAL REGISTRATION

Chinese Clinical Trial Registry. ChiCTR1900021269 . Registered 8 February 2019, http://www.chictr.org.cn/edit.aspx?pid=35837&htm=4 .

N1-Methylnicotinamide: An Anti-Ovarian Aging Hormetin?

Ovarian aging occurs due to the reduction of the quality and quantity of the oocytes, and is regulated by mitochondrial survival and apoptotic signals. Reactive Oxygen Species (ROS) are one of those signals considered detrimental to cellular homeostasis. Nowadays, ROS are regarded as a regulatory factor at low levels as it induces the stress resistance which in turn increases the longevity. It is believed that the main mechanism for the life-promoting role of the ROS mediated by the 5' Adenosine Monophosphate-activated Protein Kinase (AMPK). N1-Methylnicotinamide (MNAM) is well known for its anti-diabetic, anti-thrombotic, and anti-inflammatory activity. Aldehyde oxidase 1 (AOX1) is a detoxifying enzyme, which metabolizes the MNAM and produces two metabolites including N1-methyl-2-pyridone-5- carboxamide (2py) and N1-methyl-4-pyridone-3-carboxamide (4py). The activity of AOX1 enhances the production of ROS and improves the longevity. It has been reported that the MNAM could postpone the aging through the induction of low-level stress. It has been documented that the production of MNAM is significantly higher in the cumulus cells of the patients with Polycystic Ovary Syndrome (PCOS) and its administration on the rat model of PCOS has been shown to alleviate the hyperandrogenism and successfully activate the ovarian AMPK. Therefore, it can be hypothesized that the anti-ovarian aging effects of the MNAM are possibly based on the activation of AMPK through transient elevation of the ROS.

Effects of bone marrow mesenchymal stem cells on ovarian and testicular function in aging Sprague-Dawley rats induced by D-galactose

To investigate the effect of bone marrow mesenchymal stem cells (MSCs) on ovarian and testicular function of aging Sprague-Dawley (SD) rats induced by D-galactose (D-gal) and try to clarify the underlying functional mechanism. Adherent culture was used to isolate and purify rat MSCs. The status, proliferation and differentiation of MSCs were detected by hematoxylin-eosin staining, MTT, colony formation, flow cytometry and directional differentiation. The aging rat model was established by subcutaneous injection of D-gal, and the homing of MSCs was detected by fluorescence microscope after infusion of GFP-labeled MSCs through caudal vein. ELISA was used to detect the content of sex hormone in serum, and HE staining was used to observe the structure and morphology of testis and ovary. The isolated and purified MSCs were in good condition, and most of the cells were in G1 phase, which had strong abilities of cell proliferation, colony formation and differentiation. After GFP-labeled MSCs were infused, MSCs could be homed into the testis and ovary of rats. MSCs infusion could significantly improve the morphology of testis and ovary, increase the contents of P and E2 while decrease the contents of LH and FSH in female rats, and increase the content of testosterone in male rats (P < 0.01). It also increased the activity of superoxide dismutase (SOD) in serum of ovary and testis and significantly decreased the content of malondialdehyde (MDA). MSCs affected the content of MDA and the activity of SOD by reducing the expression of cyclin-dependent kinase inhibitor 2A (p16) and increasing proliferating cell nuclear antigen (PCNA), consequently improving the aging and injury of reproductive organs.

Coenzyme Q10 improves the in vitro maturation of oocytes exposed to the intrafollicular environment of patients on fertility treatment

OBJECTIVE

To evaluate the impact of patient follicular environment with oxidative stress on oocyte quality.

METHODS

Patients on fertility treatment with either advanced maternal age or endometriosis were asked to donate follicular fluid collected during ovum pick-up. Follicular fluid (FF) was added (20%, 10% and 5%; %V/V) to in vitro maturation (IVM) medium with mouse oocytes. Following maturation culture, the oocytes were assessed for meiosis reinitiation. In a second setup, coenzyme Q10 was added to culture medium with FF. In addition to assessing meiotic maturation, a subset of oocytes was assessed for spindle structure and chromosome alignment.

RESULTS

Supplementation of IVM medium with FF of patients of advanced maternal age (with or without antioxidants) did not have an effect on the maturation capacity of mouse oocytes. However, the addition of FF of individuals with endometriosis (without antioxidants) in the two highest concentrations affected oocyte maturation (61.5% & 57.0% maturation) compared with the lowest concentration (89.2% maturation) (p<0.05). Supplementation of medium with coenzyme Q10 did not improve the maturation rate of oocytes exposed to the FF of individuals with endometriosis (28.5±13.7%) (p<0.05). Nevertheless, preliminary analysis of spindle abnormality and chromosome alignment revealed that oocytes resuming meiosis in the presence of FF of patients with endometriosis displayed aberrant spindle morphology and chromosomal misalignment.

CONCLUSION

The follicular environment of patients with endometriosis severely affected oocyte (nuclear) maturation. In vitro maturation in the presence of coenzyme Q10 appears to be a tool for rescuing oocytes exposed to such follicular environment.

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.

Paeonia lactiflora improves ovarian function and oocyte quality in aged female mice

Although ovarian aging is a key cause of decreased ovarian function and oocyte quality, it remains a problem in infertility treatment. Therefore, this study is aimed to investigate whether Paeonia lactiflora (PL), a herb improves ovarian function and oocyte quality using aged female mice. C57BL/6 female mice aged 8 months were treated orally every day with PL of 26.5 mg/kg (n=7) and 53 mg/kg (n=7) of body weight for 4 weeks using an oral zoned needle. The control group (n=7) was treated with normal saline. Ovaries and serum were collected for the H&E stain and the evaluation of reactive oxygen species (ROS) levels, respectively. In the second experiment, female mice were orally administered with PL (26.5 mg/kg: n=12, 53 mg/kg: n=12, control: n=12) and then superovulated with PMSG and hCG, and mated with male mice. Zygotes were retrieved and cultured for 4 days. Ovaries were provided for examination of expressions of genes associated with angiogenesis (VEGF and visfatin), anti-aging (Sirt1 and Sirt2), and follicular development (c-Kit, BMP-15, and GDF-9). PL significantly increased numbers of surviving follicles (primordial, primary, secondary, and antral), numbers of zygotes retrieved, embryo development rate, and ovarian expression of VEGF, visfatin, c-Kit, BMP-15, and GDF-9 at both doses. However, ovarian expression of Sirt1 and Sirt2 was increased at 53.0 mg/kg of PL. ROS levels were not affected by PL. These results suggest that PL may possess beneficial effects regarding ovarian function and oocyte quality, possibly by activation of ovarian angiogenesis and follicular development.

A limited set of transcriptional programs define major cell types

We have produced RNA sequencing data for 53 primary cells from different locations in the human body. The clustering of these primary cells reveals that most cells in the human body share a few broad transcriptional programs, which define five major cell types: epithelial, endothelial, mesenchymal, neural, and blood cells. These act as basic components of many tissues and organs. Based on gene expression, these cell types redefine the basic histological types by which tissues have been traditionally classified. We identified genes whose expression is specific to these cell types, and from these genes, we estimated the contribution of the major cell types to the composition of human tissues. We found this cellular composition to be a characteristic signature of tissues and to reflect tissue morphological heterogeneity and histology. We identified changes in cellular composition in different tissues associated with age and sex, and found that departures from the normal cellular composition correlate with histological phenotypes associated with disease.

Ovarian aging increases small extracellular vesicle CD81+ release in human follicular fluid and influences miRNA profiles

Ovarian aging affects female reproductive potential and is characterized by alterations in proteins, mRNAs and non-coding RNAs inside the ovarian follicle. Ovarian somatic cells and the oocyte communicate with each other secreting different molecules into the follicular fluid, by extracellular vesicles. The cargo of follicular fluid vesicles may influence female reproductive ability; accordingly, analysis of extracellular vesicle content could provide information about the quality of the female germ cell.In order to identify the most significant deregulated microRNAs in reproductive aging, we quantified the small extracellular vesicles in human follicular fluid from older and younger women and analyzed the expression of microRNAs enclosed inside the vesicles. We found twice as many small extracellular vesicles in the follicular fluid from older women and several differentially expressed microRNAs. Correlating microRNA expression profiles with vesicle number, we selected 46 deregulated microRNAs associated with aging. Bioinformatic analyses allowed us to identify six miRNAs involved in TP53 signaling pathways. Specifically, miR-16-5p, miR214-3p and miR-449a were downregulated and miR-125b, miR-155-5p and miR-372 were upregulated, influencing vesicle release, oocyte maturation and stress response. We believe that this approach allowed us to identify a battery of microRNAs strictly related to female reproductive aging.

Extracellular vesicles derived from endometrial human mesenchymal stem cells enhance embryo yield and quality in an aged murine model†

Advanced age is a risk factor undermining women's fertility. Hence, the optimization of assisted reproduction techniques is an interdisciplinary challenge that requires the improvement of in vitro culture systems. Here, we hypothesize that supplementation of embryo culture medium with extracellular vesicles from endometrial-derived mesenchymal stem cells (EV-endMSCs) may have a positive impact on the embryo competence of aged oocytes. In this work, 24 weeks old B6D2 female mice were used as egg donors and in vitro fertilization assays were performed using males from the same strain (8-12 weeks); the presumptive zygotes were incubated in the presence of 0, 10, 20, 40, or 80 μg/ml of EV-endMSCs. The results from the proteomic analysis of EV-endMSCs and the classification by Reactome pathways allowed us to identify proteins closely related with the fertilization process. Moreover, in our aged murine model, the supplementation of the embryo culture medium with EV-endMSCs improved the developmental competence of the embryos as well as the total blastomere count. Finally, gene expression analysis of murine blastocysts showed significant changes on core genes related to cellular response to oxidative stress, metabolism, placentation, and trophectoderm/inner cell mass formation. In summary, we demonstrate that EV-endMSCs increase the quality of the embryos, and according to proteomic and genomic analysis, presumably by modulating the expression of antioxidant enzymes and promoting pluripotent activity. Therefore, EV-endMSCs could be a valuable tool in human assisted reproduction improving the developmental competence of aged oocytes and increasing the odds of implantation and subsequent delivery.

DNA damage and repair in the female germline: contributions to ART

BACKGROUND

DNA integrity and stability are critical determinants of cell viability. This is especially true in the female germline, wherein DNA integrity underpins successful conception, embryonic development, pregnancy and the production of healthy offspring. However, DNA is not inert; rather, it is subject to assault from various environment factors resulting in chemical modification and/or strand breakage. If structural alterations result and are left unrepaired, they have the potential to cause mutations and propagate disease. In this regard, reduced genetic integrity of the female germline ranks among the leading causes of subfertility in humans. With an estimated 10% of couples in developed countries taking recourse to ART to achieve pregnancy, the need for ongoing research into the capacity of the oocyte to detect DNA damage and thereafter initiate cell cycle arrest, apoptosis or DNA repair is increasingly more pressing.

OBJECTIVE AND RATIONALE

This review documents our current knowledge of the quality control mechanisms utilised by the female germline to prevent and remediate DNA damage during their development from primordial follicles through to the formation of preimplantation embryos.

SEARCH METHODS

The PubMed database was searched using the keywords: primordial follicle, primary follicle, secondary follicle, tertiary follicle, germinal vesical, MI, MII oocyte, zygote, preimplantation embryo, DNA repair, double-strand break and DNA damage. These keywords were combined with other phrases relevant to the topic. Literature was restricted to peer-reviewed original articles in the English language (published 1979-2018) and references within these articles were also searched.

OUTCOMES

In this review, we explore the quality control mechanisms utilised by the female germline to prevent, detect and remediate DNA damage. We follow the trajectory of development from the primordial follicle stage through to the preimplantation embryo, highlighting findings likely to have important implications for fertility management, age-related subfertility and premature ovarian failure. In addition, we survey the latest discoveries regarding DNA repair within the metaphase II (MII) oocyte and implicate maternal stores of endogenous DNA repair proteins and mRNA transcripts as a primary means by which they defend their genomic integrity. The collective evidence reviewed herein demonstrates that the MII oocyte can engage in the activation of major DNA damage repair pathway(s), therefore encouraging a reappraisal of the long-held paradigm that oocytes are largely refractory to DNA repair upon reaching this late stage of their development. It is also demonstrated that the zygote can exploit a number of protective strategies to mitigate the risk and/or effect the repair, of DNA damage sustained to either parental germline; affirming that DNA protection is largely a maternally driven trait but that some aspects of repair may rely on a collaborative effort between the male and female germlines.

WIDER IMPLICATIONS

The present review highlights the vulnerability of the oocyte to DNA damage and presents a number of opportunities for research to bolster the stringency of the oocyte's endogenous defences, with implications extending to improved diagnostics and novel therapeutic applications to alleviate the burden of infertility.

Reduced ovarian response to controlled ovarian stimulation is associated with increased oxidative stress in the follicular environment

Serum estradiol (E2) level is routinely used to monitor the ovarian response during controlled ovarian hyperstimulation (COH) and the concentration of serum E2 may influence the oocyte quality and pregnancy outcome. However, the knowledge on the association between COH induced serum E2 level, oocyte quality and embryo development is limited. Therefore we investigated the association between serum E2 level, oxidative stress in the follicular fluid and granulosa cells (GCs) response to elucidate the association between E2 level and embryological outcome. In this study, patients (n = 30) undergoing ART were categorized as 'normal responders' (NR, n = 10), 'poor responders' (PR, n = 10) and hyper responders (HR, n = 10). The follicular fluid malondialdehyde (MDA) level was determined. The total RNA extracted from GCs was subjected to analyse the relative abundance of transcripts of stress response genes (P53, caspase 3,8-oxoguanine DNA glycosylase, OGG1 and heat shock protein 70; HSP70) and embryological outcome was noted. Follicular fluid MDA level was significantly higher in PR (p < 0.01) compared NR and HR whereas number of top-quality embryos were significantly lower in PR and HR compared to NR (p < 0.01). The relative expression of P53, HSP70, and OGG1 in GCs was significantly elevated in PR (p < 0.05-0.01). An inverse relationship was established between serum E2 level vs follicular MDA level (r = -0.45; p < 0.01) and follicular MDA level vs. number of top-quality embryos (r = -0.45; p < 0.01). Hence, patients with low serum E2 had elevated oxidative stress in their follicular environment and poor quality embryos implicating the risk of oxidative stress in patients with poor ovarian response.

Evaluation of relationship between HbA1c levels and ovarian reserve in patients with type 1 diabetes mellitus

In organ or non-organ-specific autoimmune disorders, human ovary is usually the target of the autoimmune attack. We aimed to demonstrate the correlation between ovarian reserve and DM1, based on the view that women with type-1 diabetes mellitus (DM1) will have lower AMH levels secondary to poor glycemic control and autoimmune attacks. Ovarian functions of 42 patients diagnosed with DM1 who use insulin and 65 healthy volunteers were analyzed. Basal hormone and AMH levels were measured during the follicular phase. Fasting and postprandial blood glucose concentrations, HbA1c and C-peptide levels were evaluated. The mean antral follicle count (AFC) was significantly lower in DM1 patients than in healthy controls (p = .001). The AMH levels were lower in women with DM1 than in the controls (p = .001). The HbA1c values of DM1 patients, who formed the study group, was significantly higher than the control group. Ovarian reserve that is evaluated with serum AMH level is affected by poor glycemic control in type 1 diabetes. Due to the time of the autoimmune damage in the ovaries and the observable effects of this damage, more comprehensive and longer-term studies are needed to be conducted for the follow-up of reproductive abnormalities.

Roles of insulin-like growth factor II in regulating female reproductive physiology

The number of growth factors involved in female fertility has been extensively studied, but reluctance to add essential growth factors in culture media has limited progress in optimizing embryonic growth and implantation outcomes, a situation that has ultimately led to reduced pregnancy outcomes. Insulin-like growth factor II (IGF-II) is the most intricately regulated of all known reproduction-related growth factors characterized to date, and is perhaps the predominant growth factor in human ovarian follicles. This review aims to concisely summarize what is known about the role of IGF-II in follicular development, oocyte maturation, embryonic development, implantation success, placentation, fetal growth, and in reducing placental cell apoptosis, as well as present strategies that use growth factors in culture systems to improve the developmental potential of oocytes and embryos in different species. Synthesizing the present knowledge about the physiological roles of IGF-II in follicular development, oocyte maturation, and early embryonic development should, on the one hand, deepen our overall understanding of the potential beneficial effects of growth factors in female reproduction and on the other hand support development (optimization) of improved outcomes for assisted reproductive technologies.

Environmental toxin exposure in polycystic ovary syndrome women and possible ovarian neoplastic repercussion

Purpose: Over the last two decades, increasing attention has been paid to environmental toxins and their effects on the female reproductive system. Endocrine disrupting chemicals (EDCs) are exogenous substances or mixtures that can mimic the action of steroid hormones and interfere with their metabolism. Advanced glycation end products (AGEs) are proinflammatory molecules that can interact with cell surface receptors and mediate the triggering of proinflammatory pathways and oxidative stress. The purpose of this review is to explore the effects of environmental toxin exposure in the pathogenesis of both polycystic ovary syndrome (PCOS) and OC (ovarian cancer), considered separately, and also to evaluate possible neoplastic ovarian repercussion after exposure in patients diagnosed with PCOS.Materials and methods: We searched PubMed for articles published in the English language with the use of the following MeSH search terms: "polycystic ovary syndrome" and "ovarian cancer" combined with "endocrine disruptors". Titles and abstracts were examined and full articles that met the selection criteria were retrieved. A manual search of review articles and cross-references completed the search.Results: Extensive data from different studies collected in recent years concerning the effects of EDC/AGE exposure have confirmed their role in the pathophysiology of both PCOS and OC. They favor PCOS/OC development through different mechanisms that finally lead to hormonal and metabolic disruption and epigenetic modifications.Conclusions: Environmental toxin exposure in PCOS women could favor neoplastic transformation by exacerbating and potentiating some PCOS features. Further research, although difficult, is needed in order to prevent further diffusion of these substances in the environment, or at least to provide adequate information to the population considered at risk.

High Salt Diet Affects the Reproductive Health in Animals: An Overview

Simple summary

Halophytic plants are a promising animal feed source. However, the extreme NaCl₂ salt content constraints their use. Excess diet salt adversely affects growth performance and animal’s reproduction worldwide. This review focuses on the impact of high salt intake on growth performance and reproduction ability in animals.

Abstract

Salinity is a reliable issue of crop productivity loss in the world and in certain tropical and subtropical zones. However, tremendous progress in the genetic improvement of plants for salinity tolerance has been made over several decades. In light of this, halophytic plants can be used as animal feeds and have promising features because they are a good feed resource. However, the main constraint of saline pasture systems is the extreme concentration of NaCl salt in drinking water and forage plants for grazing animals. Ecological reports revealed that excess diet salt causes mortality and morbidity worldwide. Animal fed halophytic forages may have adverse effects on growth performance and reproductive function in males and females due to inducing reductions in hormone regulation, such as testosterone, FSH, LH, and leptin. It was indicated that high salt intake promotes circulating inflammatory factors in the placenta and is associated with adversative effects on pregnancy. This review focuses on the scientific evidence related to the effect of high salt intake on growth performance, spermatogenesis, sperm function, and testicular morphology changes in male animals. In addition, the review will also focus on its effect on some female reproductive features (e.g., ovarian follicle developments, placental indices, and granulosa cell function).

Autophagy in Female Fertility: A Role in Oxidative Stress and Aging

Significance: The precipitous age-related decline in female fertility is intimately associated with a reduction in both the quantity and quality of the germline (oocytes). Although complex etiologies undoubtedly contribute to the deterioration of oocyte quality, increasing attention has focused on the pervasive impact of oxidative stress. Indeed, the prolonged lifespan of the meiotically arrested oocyte places this cell at heightened risk of oxidative lesions, which commonly manifest in dysregulation of protein homeostasis (proteostasis). Although oocytes are able to mitigate this threat via the mobilization of a sophisticated network of surveillance, repair, and proteolytic pathways, these defenses are themselves prone to age-related defects, reducing their capacity to eliminate oxidatively damaged proteins. Recent Advances: Here, we give consideration to the quality control mechanisms identified within the ovary that afford protection to the female germline. Our primary focus is to review recent advances in our understanding of the autophagy pathway and its contribution to promoting oocyte longevity and modulating pathophysiological responses to oxidative stress. In addition, we explore the therapeutic potential of emerging strategies to fortify autophagic activity. Critical Issues: The complex interplay of oxidative stress and autophagy has yet to be fully elucidated within the context of the aging oocyte and surrounding ovarian environment. Future Directions: Emerging evidence provides a strong impetus to resolve the causal link between autophagy and oxidative stress-driven pathologies in the aging oocyte. Such research may ultimately inform novel therapeutic strategies to combat the age-related loss of female fertility via fortification of intrinsic autophagic activity.