Multiple superovulations alter histone modifications in mouse early embryos

High-dose estrogen impairs demethylation of H3K27me3 by decreasing Kdm6b expression during ovarian hyperstimulation in mice

Given that ovarian stimulation is vital for assisted reproductive technology (ART) and results in elevated serum estrogen levels, exploring the impact of elevated estrogen exposure on oocytes and embryos is necessary. We investigated the effects of various ovarian stimulation treatments on oocyte and embryo morphology and gene expression using a mouse model and estrogen-treated mouse embryonic stem cells (mESCs). Female C57BL/6J mice were subjected to two types of conventional ovarian stimulation and ovarian hyperstimulation; mice treated with only normal saline served as controls. Hyperstimulation resulted in high serum estrogen levels, enlarged ovaries, an increased number of aberrant oocytes, and decreased embryo formation. The messenger RNA (mRNA)‍-sequencing of oocytes revealed the dysregulated expression of lysine-specific demethylase 6b (Kdm6b), which may be a key factor indicating hyperstimulation-induced aberrant oocytes and embryos. In vitro, Kdm6b expression was downregulated in mESCs treated with high-dose estrogen; treatment with an estrogen receptor antagonist could reverse this downregulated expression level. Furthermore, treatment with high-dose estrogen resulted in the upregulated expression of histone H3 lysine 27 trimethylation (H3K27me3) and phosphorylated H2A histone family member X (γ-H2AX). Notably, knockdown of Kdm6b and high estrogen levels hindered the formation of embryoid bodies, with a concomitant increase in the expression of H3K27me3 and γ-H2AX. Collectively, our findings revealed that hyperstimulation-induced high-dose estrogen could impair the demethylation of H3K27me3 by reducing Kdm6b expression. Accordingly, Kdm6b could be a promising marker for clinically predicting ART outcomes in patients with ovarian hyperstimulation syndrome.

Maternal exposure to nicotine causes oxidative stress and inflammatory changes in the ovaries of rats' adult offspring

Nicotine is one of the most toxic substances found in cigarettes, but also found in chewing tobacco gum, patches and vaping products (electronic cigarettes). In addition to being a highly addictive chemical, it is capable of reducing fertility in men and women. In the ovaries, it can induce morphological changes and impair the formation of follicles, being a possible cause of changes in the reproductive cycle and anticipation of menopause in women whose mothers smoked during pregnancy. By increasing the generation of free radicals, nicotine can induce oxidation in biological samples and change the expression of inflammatory cytokines. It damages the immune system and many other cells of newborns exposed prenatally. Despite its teratogenic potential, many women continue to use this drug during pregnancy and lactation. Thus, this work aims to analyze the effects of maternal exposure to nicotine on the ovaries of adult rats. To this end, 10 rats received nicotine throughout pregnancy and lactation. Their offspring were euthanized around 90 days-old, in the metestrus phase, for ovary collection and analysis of oxidative stress and inflammation. The results showed that exposure to nicotine increased MDA level, but did not cause damage to the DNA of ovarian cells (8-OHdG). It also increased IL-1β and anti-inflammatory protein AnxA1 and receptor Fpr1, and reduced the mast cell population in ovaries. We concluded that maternal exposure to nicotine is capable of inducing oxidative stress and leading to inflammatory changes in the ovaries of adult offspring exposed during the intrauterine and breastfeeding phases.

Effects of multisuperovulation on the transcription and genomic methylation of oocytes and offspring

BACKGROUND

Controlled ovarian stimulation is a common skill of assisted reproductive technologies (ARTs). In the clinic, some females would undergo more than one controlled ovarian stimulation cycle. However, few studies have focused on the influence of multi-superovulation on oocytes and offspring.

RESULTS

Here, we found that multi-superovulation disrupted the transcriptome of oocytes and that the differentially expressed genes (DEGs) were associated mainly with metabolism and fertilization. The disruption of mRNA degradation via poly (A) size and metabolism might be a reason for the reduced oocyte maturation rate induced by repeated superovulation. Multi-superovulation results in hypo-genomic methylation in oocytes. However, there was an increase in the methylation level of CGIs. The DMRs are not randomly distributed in genome elements. Genes with differentially methylated regions (DMRs) in promoters are enriched in metabolic pathways. With increasing of superovulation cycles, the glucose and insulin tolerance of offspring is also disturbed.

CONCLUSIONS

These results suggest that multi-superovulation has adverse effects on oocyte quality and offspring health.

Epigenetic modifications of gonadotropin receptors can regulate follicular development

The spatiotemporal transcription of follicle-stimulating hormone receptor (FSHR) and luteinizing hormone/human chorionic gonadotropin receptor (LHCGR) are crucial events for follicular development. However, their regulatory mechanisms are unclear. DNA methylation and histone acetylation are the main epigenetic modifications, and play important roles in transcriptional expression, which regulate cell responses including cell proliferation, senescence and apoptosis. This review will discuss the dynamic epigenetic modifications of FSHR and LHCGR that occur during the process of follicular development and their response to gonadotropins. In addition, some alteration patterns that occur during these epigenetic modifications, as well as their retrospect retrotransposons, which regulate the gene expression levels of FSHR and LHCGR will be discussed.

Participation of preovulatory follicles in the activation of primordial follicles in mouse ovaries

The mechanisms behind the selection and initial recruitment of primordial follicles (PmFs) from the non-growing PmF pool during each estrous cycle in females remain largely unknown. This study demonstrates that PmFs closest to the ovulatory follicle are preferentially activated in mouse ovaries under physiological conditions. PmFs located within 40 μm of the ovulatory follicles were more likely to be activated compared to those situated further away during the peri-ovulation period. Repeated superovulation treatments accelerated the depletion of the PmF reserve, whereas continuous suppression of ovulation delayed PmF reserve consumption. Spatial transcriptome sequencing of peri-ovulatory follicles revealed that ovulation primarily induces the degradation and remodeling of the extracellular matrix (ECM). This ECM degradation reduces mechanical stress around PmFs, thereby triggering their activation. Specifically, Cathepsin L (CTSL), a cysteine proteinase and lysosomal enzyme involved in ECM degradation, initiates the activation of PmFs adjacent to ovulatory follicles in a distance-dependent manner. These findings highlight the link between ovulation and selective PmF activation, and underscore the role of CTSL in this process under physiological conditions.

Glyphosate modifies the gene expression and migration of trophoblastic cells without altering the process of angiogenesis or the implantation of blastocysts in vitro

Adverse pregnancy outcomes have been associated with the presence of glyphosate (G) in umbilical cord, serum, and urine samples from pregnant women. Our aim was to study the effect of G on blastocyst implantation using an in vitro mouse model, and the migration and acquisition of endothelial phenotype of the human trophoblastic HTR8/SVneo (H8) cells. In mouse blastocysts, no differences in attachment time and implantation outgrowth area were observed after G exposure. H8 cell migration was stimulated by 0.625 μM G without cytotoxicity. After 6 h, the mRNA expression of vascular endothelial growth factor (VEGF) and C-C motif chemokine ligand 2 (CCL2) was upregulated in H8 cells exposed to 1.25 μM G when compared vehicle-treated cells (p ≤ 0.05). No differences were observed in interleukin 11, VEGF receptor 1, and coagulation factor II thrombin receptor in H8 cells exposed to different concentrations of G for 6 h compared to the vehicle. Interestingly, exposure to G did not alter angiogenesis as measured by a tube formation assay. Taken all together, these results suggest that G exposure may contribute as a risk factor during pregnancy, due to its ability to alter trophoblast migration and gene expression.

The Role of One-Carbon Metabolism and Methyl Donors in Medically Assisted Reproduction: A Narrative Review of the Literature

One-carbon (1-C) metabolic deficiency impairs homeostasis, driving disease development, including infertility. It is of importance to summarize the current evidence regarding the clinical utility of 1-C metabolism-related biomolecules and methyl donors, namely, folate, betaine, choline, vitamin B12, homocysteine (Hcy), and zinc, as potential biomarkers, dietary supplements, and culture media supplements in the context of medically assisted reproduction (MAR). A narrative review of the literature was conducted in the PubMed/Medline database. Diet, ageing, and the endocrine milieu of individuals affect both 1-C metabolism and fertility status. In vitro fertilization (IVF) techniques, and culture conditions in particular, have a direct impact on 1-C metabolic activity in gametes and embryos. Critical analysis indicated that zinc supplementation in cryopreservation media may be a promising approach to reducing oxidative damage, while female serum homocysteine levels may be employed as a possible biomarker for predicting IVF outcomes. Nonetheless, the level of evidence is low, and future studies are needed to verify these data. One-carbon metabolism-related processes, including redox defense and epigenetic regulation, may be compromised in IVF-derived embryos. The study of 1-C metabolism may lead the way towards improving MAR efficiency and safety and ensuring the lifelong health of MAR infants.

A mutual comparison of pregnancy outcomes between different conception modes: a propensity score matching based retrospective cohort study

Background

Assisted reproductive technology (ART) has been reported to have negative effects on maternal and neonatal health. Ovulation induction (OI) was reported to be associated with alteration of epigenetic modification of mice embryos, and extinguishing the influence of ovulation induction and in vitro operations on maternal and neonatal health will bring benefits for reducing side effects. The present study aimed to determine whether ovulation induction alone and ART are associated with adverse pregnancy outcomes and whether ART could induce a higher risk than ovulation induction alone.

Methods

A total of 51,172 cases with singleton live birth between Jan 2016 and May 2019 at the International Peace Maternal and Child Health Hospital were included in this study. Conception modes documented during registration were classified into natural conception (NC), OI, and ART. Pregnancy outcomes of the three groups with balanced baseline characteristics by propensity score matching were compared. The relative risks of maternal and neonatal outcomes were calculated by logistic regression analysis.

Results

Compared with natural conception, infertility treatments are associated with gestational diabetes (OI: OR 1.72, 95% CI 1.31-2.27; ART: OR 1.67, 95% CI 1.26-2.20), preeclampsia/eclampsia (OI: OR 1.86, 95% CI 1.03-3.36; ART: OR 2.23, 95% CI 1.26-3.92). Even if gestational diabetes, gestational hypertension, and placental problems were adjusted, infertility treatments are associated with birth before 37 weeks (OI: OR 1.99, 95% CI 1.28-3.12; ART: OR 1.70, 95% CI 1.08-2.69), low birth weight (OI: OR 2.19, 95% CI 1.23-3.91; ART: OR 1.90, 95% CI 1.05-3.45), and SGA (OI: OR 2.42, 95% CI 1.20-4.87; ART: OR 2.56, 95% CI 1.28-5.11). ART but not OI is associated with a higher risk of birth before 34 weeks (OR:3.12, 95% CI 1.21-8.05). By comparing the OI group with the ART group, we only found that ART could induce a higher ratio of placental problems (5.0%, 26/518 vs 2.1%, 11/519, p<0.05).

Conclusion

Both OI and ART are associated with adverse pregnancy outcomes. ART induced comparable negative effects with OI on gestational complications, birth weight, and premature birth (<37 weeks). However, ART resulted in a higher risk of placental problems than group NC and OI. The incidence of birth before 34 weeks of gestation in the ART group tends to be higher than in the OI group, but not statistically significant. The side effects of ART may originate from OI.

Maternal age and gonadotrophin elevation cooperatively decrease viable ovulated oocytes and increase ootoxicity, chromosome-, and spindle-misalignments: '2-Hit' and 'FSH-OoToxicity' mechanisms as new reproductive aging hypotheses

While there is consensus that advanced maternal age (AMA) reduces oocyte yield and quality, the notion that high FSH reduces oocyte quality and causes aneuploidy remains controversial, perhaps due to difficulties controlling the confounding variables of age and FSH levels. Here, contributions of age and gonadotrophin elevation were separately controlled using a mouse model of human female reproductive aging. Ovulated oocytes were collected from young and midlife mice after 0-, 2.6-, or 17-day treatment with the FSH analog equine chorionic gonadotrophin (eCG), to model both exogenous FSH elevation within a single treatment cycle (as in controlled ovarian stimulation (COS)), and chronic endogenous FSH elevation during multiple cycles (as in diminished ovarian reserve). After 17-day eCG, fewer total oocytes/mouse are ovulated in midlife than young mice, and a precipitous decline in viable oocytes/mouse is observed in midlife but not young mice throughout eCG treatment. eCG is potently ootoxic to ovulatory oocytes and strongly induces chromosome- and spindle-misalignments within 2.6 days of eCG in midlife, but only after 17 days in young mice. These data indicate that AMA increases susceptibility to multiple adverse effects of elevated FSH activity in ovulated oocytes, including declines in total and viable oocytes/mouse, and induction of ootoxicity and aneuploidy. Two hypotheses are proposed for underlying causes of infertility in women. The FSH OOToxicity Hypothesis ('FOOT Hypothesis') posits that high FSH is ootoxic to ovulatory oocytes and that FSH ootoxicity is a root cause of low pregnancy success rates in naturally cycling women with high FSH and IUI patients undergoing COS. The '2-Hit Hypothesis' posits that AMA increases susceptibility to FSH-induced ootoxicity and aneuploidy.

Repeated controlled ovarian stimulation-induced ovarian and uterine damage in mice through the PI3K/AKT signaling pathway

The effects of repeated controlled ovarian stimulation (COS) on the female reproductive system are still controversial. This study investigated the effects of repeated COS on the ovaries and uterus of mice and its possible mechanism. Female ICR (Institute of Cancer Research) mice were subjected to the COS using pregnant mare serum gonadotropin (PMSG) and human chorionic gonadotropin (hCG) for 1, 3, 5, and 7 cycles. Serum hormone levels, reactive oxidative stress (ROS), 8-hydroxy-2'-deoxyguanosine (8-OHdG), total antioxidant capacity (T-AOC), and superoxide dismutase (SOD) in the mouse ovary and uterus were analyzed by ELISA. The morphology of the ovary and endometrium, ovarian apoptosis, and expressions of the vascular endothelial growth factor (VEGF), leukemia inhibitory factor (LIF), PI3K, AKT, Bax, and Bcl-2 in the ovarian and uterine tissues were tested by hematoxylin-eosin (HE) staining, immunohistochemistry, and western blot. The results showed that repeated COS significantly decreased the hormone level (estradiol, progesterone and anti-Müllerian hormone), high-quality of the MII oocyte ratio, oocyte and embryo number, antioxidant capacity (T-AOC, SOD activity), and the protein level of Bcl-2, LIF, and VEGF, but increased the oxidative damage (ROS, 8-OHdG content), embryo fragment ratio, and expression of pro-apoptotic protein Bax. In addition, the expressions of p-PI3K and p-AKT also decreased with the increase of COS cycle. In conclusion, repeated COS causes ovarian and uterus damage possibly through the PI3K/AKT signaling pathway, and this finding may provide some experimental basis for guiding clinical treatment.

Repeated Superovulation Accelerates Primordial Follicle Activation and Atresia

For humans, ARTs (assisted reproductive technologies) have become the most effective method to treat subfertility/infertility in clinic. To obtain enough oocytes during ART, ovarian stimulation is performed by exogenous hormones, and some patients undergo several ovarian stimulation cycles. Although some adverse effects of ARTs on women and offspring are reported, few studies are focused on the effects of multiple superovulation on ovarian reserve. In the present study, we found that repeated superovulation significantly reduced primordial follicle number and the serum AMH. Compared to the decreased antral follicle number, the expression of genes related to primordial follicle activation, such as Foxo3, Akt, and Rptor, and the atretic follicle number in ovaries were increased by superovulation times. We further found that repeated superovulation reduced the plasma level of FSH, LH, and estradiol, and increased the expression of genes related to apoptosis (Bax, Casp3 (caspase-3), Casp8, and Casp9) in granulosa cells, providing evidence that repeated superovulation disrupted the balance between survival and death in granulosa cells. In summary, our results suggest that repeated superovulation has adverse effects on folliculogenesis.

He's Yangchao Recipe Ameliorates Ovarian Oxidative Stress of Aging Mice under Consecutive Superovulation Involving JNK- And P53-Related Mechanism

Objective

To evaluate the effects of He's Yangchao Recipe (HSYC) on ameliorating ovarian oxidative stress of aging mice under consecutive superovulation.

Methods

An 8-month-old C57BL/6 female mouse was chosen to establish an aging model under ovarian hyperstimulation. Mice were randomly separated into four groups: R1 as the control group, R4 as the model group, NR4 with N-acetyl-L-cysteine (NAC) administration, and TR4 with HSYC administration. Oocyte collection, in vitro fertilization, and embryo culture were performed. The serum hormone levels were measured by enzyme-linked immunosorbent assays (ELISA); the reactive oxygen species (ROS) level of oocytes, the number of growing follicles, corpus luteum, ovulated oocytes, and developing embryos at each stage, along with the proportions of fragmented oocytes and abnormal mitochondria in granulosa cells (GCs) and the apoptosis rate of GCs were calculated; the mRNA and protein levels of JNK, P53, BAX were detected by real-time PCR and the Simple Western System.

Results

HSYC enhanced estradiol, progesterone, and inhibin-B levels and increased growing follicle and corpus luteum and ovulated egg counts compared to the R4 group (P < 0.05), whereas it decreased the proportions of fragmented oocytes (P < 0.01); Meanwhile, embryos from mice subjected to four superovulation cycles with HSYC treated had a higher hatching potential. The ROS level of oocytes is downregulated by HSYC (P < 0.01) and the percentage of abnormal mitochondrial in ovaries of the TR4 group was also significantly declined compared to the R4 group (P < 0.05); the most TUNEL-positive cells proportion was detected in the R4 group; nevertheless, HSYC effectively attenuated this detrimental effect (P < 0.05). The mRNA and protein expressions of JNK and P53 in ovary tissues were reduced in the TR4 group while these genes were upregulated by repeated superovulation (P < 0.05).

Conclusions

HSYC exerted promising effects on promoting the diminished ovarian reserve and decreased oocyte quality induced by both aging and consecutive ovarian superovulation, potentially via the ROS/JNK/p53 pathway.

Epigenetic Risks of Medically Assisted Reproduction

Since the birth of Louise Joy Brown, the first baby conceived via in vitro fertilization, more than 9 million children have been born worldwide using assisted reproductive technologies (ART). In vivo fertilization takes place in the maternal oviduct, where the unique physiological conditions guarantee the healthy development of the embryo. During early embryogenesis, a major wave of epigenetic reprogramming takes place that is crucial for the correct development of the embryo. Epigenetic reprogramming is susceptible to environmental changes and non-physiological conditions such as those applied during in vitro culture, including shift in pH and temperature, oxygen tension, controlled ovarian stimulation, intracytoplasmic sperm injection, as well as preimplantation embryo manipulations for genetic testing. In the last decade, concerns were raised of a possible link between ART and increased incidence of imprinting disorders, as well as epigenetic alterations in the germ cells of infertile parents that are transmitted to the offspring following ART. The aim of this review was to present evidence from the literature regarding epigenetic errors linked to assisted reproduction treatments and their consequences on the conceived children. Furthermore, we provide an overview of disease risk associated with epigenetic or imprinting alterations in children born via ART.

Temporary Increased LDL-C in Offspring with Extreme Elevation of Maternal Preconception Estradiol: A Retrospective Cohort Study

Objective

To investigate the effect of maternal estradiol (E₂) elevation on long-term metabolic manifestations in the offspring.

Study Design and Setting

This was a retrospective cohort study. Overall, 3690 children conceived by in vitro fertilization (IVF)/intracytoplasmic sperm injection (ICSI) between July 2014 and December 2017 were recruited and divided into four groups categorized by maternal E₂ quartiles (Q1, <2420; Q2, 2420–3839; Q3, 3839–5599; and Q4, ≥5599 pg/mL). The metabolic profiles were measured during childhood. Linear mixed models were used to evaluate the association between maternal E₂ elevation and metabolic phenotypes of the offspring.

Results

Lipoprotein cholesterol (LDL-C) was significantly higher in the highest quartile group than in the lowest quartile group during infancy (adjusted mean difference [95% confidence interval, CI]): 0.11 [0.02, 0.20], P = 0.005), but the difference disappeared in the later childhood phase. In children born after fresh embryo transfer, LDL-C showed an increasing trend with the increase in maternal E₂ level (adjusted mean difference [95% CI]: Q2 vs Q1, −0.01 [−0.11, 0.08], Q3 vs Q1, 0.06 [−0.04, 0.15], Q4 vs Q1, 0.10 [0, 0.20]). Other metabolic variables were comparable across increasing quartiles of maternal E₂ levels.

Conclusion

This study demonstrates a temporary increase in LDL-C levels in infants with higher levels of maternal preconception E₂ levels. However, the long-term safety of hyperestrogens after ovarian stimulation in the next generation is favorable. The mechanism underlying the transiently increased metabolic dysfunction risk in infants conceived by IVF/ICSI requires investigation in future studies.

Dynamics of Known Long Non-Coding RNAs during the Maternal-to-Zygotic Transition in Rabbit

The control of pre-implantation development in mammals undergoes a maternal-to-zygotic transition (MZT) after fertilization. The transition involves maternal clearance and zygotic genome activation remodeling the terminal differentiated gamete to confer totipotency. In the study, we first determined the profile of long non-coding RNAs (lncRNAs) of mature rabbit oocyte, 2-cell, 4-cell, 8-cell, and morula embryos using RNA-seq. A total of 2673 known rabbit lncRNAs were identified. The lncRNAs exhibited dynamic expression patterns during pre-implantation development. Moreover, 107 differentially expressed lncRNAs (DE lncRNAs) were detected between mature oocyte and 2-cell embryo, while 419 DE lncRNAs were detected between 8-cell embryo and morula, consistent with the occurrence of minor and major zygotic genome activation (ZGA) wave of rabbit pre-implanted embryo. This study then predicted the potential target genes of DE lncRNAs based on the trans-regulation mechanism of lncRNAs. The GO and KEGG analyses showed that lncRNAs with stage-specific expression patterns promoted embryo cleavage and synchronic development by regulating gene transcription and translation, intracellular metabolism and organelle organization, and intercellular signaling transduction. The correlation analysis between mRNAs and lncRNAs identified that lncRNAs ENSOCUG00000034943 and ENSOCUG00000036338 may play a vital role in the late-period pre-implantation development by regulating ILF2 gene. This study also found that the sequential degradation of maternal lncRNAs occurred through maternal and zygotic pathways. Furthermore, the function analysis of the late-degraded lncRNAs suggested that these lncRNAs may play a role in the mRNA degradation in embryos via mRNA surveillance pathway. Therefore, this work provides a global view of known lncRNAs in rabbit pre-implantation development and highlights the role of lncRNAs in embryogenesis regulation.

A comparison study of superovulation strategies for C57BL/6J and B6D2F1 mice in CRISPR-Cas9 mediated genome editing

Reproductive techniques such as superovulation and in vitro fertilisation (IVF) have been widely used in generating genetically modified animals. The current gold standard for superovulation in mice is using coherent treatments of equine chorionic gonadotropin (eCG) and human chorionic gonadotropin (hCG). An alternative method using inhibin antiserum (IAS) instead of eCG has been recently reported. Here, we evaluate different superovulation strategies in C57BL/6J and B6D2F1 mice. Firstly, we found that using 5-week-old C57BL/6J and 4-week-old B6D2F1 donors could achieve better superovulation outcomes. Then, we compared eCG-hCG, IAS-hCG and eCG-IAS-hCG with different dosages in both mouse strains. Significantly increased numbers of oocytes were obtained by using IAS-hCG and eCG-IAS-hCG methods. However, low fertilisation rates (36.3-38.8%) were observed when natural mating was applied. We then confirmed that IVF could dramatically ameliorate the fertilisation rates up to 89.1%. Finally, we performed CRISPR-Cas9 mediated genome editing targeting Scn11a and Kcnh1 loci, and successfully obtained mutant pups using eCG-hCG and IAS-hCG induced zygotes, which were fertilised by either natural mating or IVF. Our results showed that IAS is a promising superovulation reagent, and the efficiency of genome editing is unlikely to be affected by using IAS-induced zygotes.

Ovulation induction is associated with altered growth but with preservation of normal metabolic function in murine offspring

OBJECTIVE

To study the effects of ovulation induction on mouse postnatal health, with a focus on growth pattern and glucose tolerance. To study the effect of ovulation induction on DNA methylation, we took advantage of the agouti viable yellow (Avy) mouse.

DESIGN

Animal study.

SETTING

University Setting.

ANIMALS

Agouti viable yellow (Avy) mice on a C57BL/6 background.

INTERVENTION(S)

Avy female mice were either allowed to mate spontaneously (control group, C) or after superovulation with 5 IU of PMSG and hCG (ovulation induction group, OI).

MAIN OUTCOME MEASURE(S)

Birth parameters and postnatal growth of the offspring were followed up to 29 weeks of age. Body composition analysis was performed by EchoMRI; fasting insulin, intraperitoneal glucose tolerance tests, and glucose-stimulated insulin secretion by beta cells were assessed to study glucose metabolism.

RESULT(S)

Mice born to superovulated dams had lower survival rates, shorter anogenital distances, and shorter crown-rump lengths. Female mice generated by OI weighed less at birth, whereas male mice generated by OI had lower weight gain and had reduced lean mass. Glucose parameters, including islet functions, did not differ between the groups. No difference in agouti coat color was noted between the groups.

CONCLUSION(S)

Ovulation induction resulted in mice having increased morphometric differences at birth and male mice showing reduced weight gain but no difference in glucose tolerance or agouti coat color.

Vitamin C protects early mouse embryos against juglone toxicity

Juglone, a naphthoquinone isolated from many species of the Juglandaceae (walnut) family, has been used in traditional Chinese medicine for centuries for its various pharmacological effects. Our previous research found its toxic effects on oocytes maturation. But we still know a little about its toxic effects on embryo development. Here, we used mouse embryo as a model to explore the effects of juglone on early mammalian embryo development. Exposure to juglone significantly decreased the development rate in early mouse embryos in vitro. Moreover, juglone exposure led to developmental arrest by disturbing mitochondrial function, producing abnormal epigenetic modifications, inducing high levels of oxidative stress and DNA damage, and increasing the rate of embryonic cell apoptosis. However, vitamin C (VC) ameliorated the toxic effects of juglone to a certain extent. Overall, juglone has a toxic effect on early embryo development through the generation of ROS and apoptosis. But VC was able to protect against these juglone-induced defects. These results not only give a new perspective on juglone's pharmacological effects on early mammalian embryo development, but also provide ideas for the better application of this agent in traditional Chinese medicine.