Psychological stressors involved in the pathogenesis of premature ovarian insufficiency and potential intervention measures

Premature ovarian insufficiency (POI) is a common gynecological endocrine disease, which seriously affects women's physical and mental health and fertility, and its incidence is increasing year by year. With the development of social economy and technology, psychological stressors such as anxiety and depression caused by social, life and environmental factors may be one of the risk factors for POI. We used PubMed to search peer-reviewed original English manuscripts published over the last 10 years to identify established and experimental studies on the relationship between various types of stress and decreased ovarian function. Oxidative stress, follicular atresia, and excessive activation of oocytes, caused by Stress-associated factors may be the main causes of ovarian function damage. This article reviews the relationship between psychological stressors and hypoovarian function and the possible early intervention measures in order to provide new ideas for future clinical treatment and intervention.

Chronic stress decreases fertility parameters in female rats

Multiple effects of stress on health have been reported; however, reproductive alterations in oocytes and cumulus cells have not been fully described. In females, chronic stress has been shown to produce alterations in the estrous cycle, to decrease oocyte in vivo maturation, and to increase the percentage of abnormal oocytes. The aim of this study was to evaluate whether the oocytes from chronically stressed female rats could recover and mature in vitro by providing them with all the necessary culture conditions, as well as to evaluate the functionality of the GAP junctions, and the viability and DNA integrity of the cumulus cells, which are crucial for the complete maturation and development of the oocyte. For this, rats were stressed daily by cold water immersion (15 °C) during 15 min for 30 consecutive days. Corticosterone serum levels in rats increased as an indicator of stress. Chronic stress decreased the percentage of in vitro matured oocytes because the cumulus cells presented irreparable damage to their DNA that led to their death, being unable to establish bidirectional communication with the oocyte for its meiotic resumption through the GAP junctions, which were also damaged. These findings could partially explain an association between stress and infertility.

Restraint stress of female mice during oocyte development facilitates oocyte postovulatory aging

Studies suggest that psychological stress on women can impair their reproduction and that postovulatory oocyte aging (POA) might increase the risk of early pregnancy loss and affect offspring's reproductive fitness and longevity. However, whether psychological stress during oocyte development would facilitate POA is unknown but worth exploring to understand the mechanisms by which psychological stress and POA damage oocytes. This study observed effects of female restraint stress during oocyte development (FRSOD) on oocyte resistance to POA. Female mice were restrained for 48 h before superovulation, and they were sacrificed at different intervals after ovulation to recover aging oocytes for analyzing their early and late aged characteristics. The effects of FRSOD on aging oocytes included: (1) increasing their susceptibility to activation stimulus with elevated cytoplasmic calcium; (2) impairing their developmental potential with downregulated expression of development-beneficial genes; (3) facilitating degeneration, cytoplasmic fragmentation and apoptosis; (4) worsening the disorganization of cortical granules and spindle/chromosomes; and (5) impairing redox potential with increased oxidative stress. In conclusion, FRSOD impairs oocyte resistance to POA, so that stressed oocytes become aged significantly quicker than unstressed controls. Thus, couples wishing to achieve pregnancy should take steps to avoid not only fertilization of aged oocytes but also pregestational stressful life events.

Psycho-emotional stress, folliculogenesis, and reproductive technologies: clinical and experimental data

Modern life, especially in large cities, exposes people to a high level of noise, high density of population, disrupted sleeping, large amount of excessive and controversial information as well as to other negative factors; all this may cause chronic psycho-emotional stress. The latest publications often use the term “Syndrome of megalopolis”, which means disruption of sleeping, high anxiety, and altered reproductive function. Medical treatment of infertility may also be considered as a stress factor, especially when infertility lasts for years and is aggravated with emotional frustration. Long-lasting distress may worsen health in general and suppress reproductive function, in particular. The review presents the data on the effects of maternal stress on folliculogenesis, especially when assisted reproductive technologies (ARTs) are used. Clinical data are presented alongside data from laboratory animal experiments. Different maternal stress models are taken into account in respect of their inf luence on oocyte maturation and embryo development. The interfering of psycho-emotional stress and reproductive function is the focus of the review. In these situations, exogenous hormones compensate for the stress-related disruption of the hypothalamic-pituitary-gonadal axis. When ARTs are implemented, stress-induced disruption of oogenesis is realized not via a decrease in hypothalamic and pituitary hormones, but by other ways, which involve paracrine mechanisms described in this review. Based on the literature analysis, one may conclude that stress negatively affects oocyte maturation in the ovary and suppresses subsequent embryo development. The role of some ovarian paracrine factors, such as BDNF, GDF-9, HB-EGF, TNF-α, and some others has been elucidated

Complementary and Alternative Medicine for Premature Ovarian Insufficiency: A Review of Utilization and Mechanisms

Premature ovarian insufficiency (POI) is defined as a decline in ovarian function before the age of 40 and is one of the leading causes of infertility in women. The etiology is complex, and the pathogenesis is not clear. The main treatment is hormone replacement therapy, but a growing body of data confirms that such treatment can increase the risk of endometrial disease and cardiovascular disease. Complementary and alternative medicine (CAM) has been widely used in patients with POI due to its limited adverse reactions and high efficiency. According to literature reports, CAM therapy for POI mainly includes traditional Chinese medicine, acupuncture, psychotherapy, dietary supplements, and exercise therapy. This article reviews the application of CAM in the treatment of POI and attempts to determine the therapeutic effects and the mechanisms behind these effects based on existing clinical and experimental studies in order to provide theoretical support for the treatment of POI.

Topoisomerase II dysfunction causes metaphase I arrest by activating aurora B, SAC and MPF and prevents PB1 abscission in mouse oocytes†

Oocyte aneuploidy is caused mainly by chromosome nondisjunction and/or unbalanced sister chromatid pre-division. Although studies in somatic cells have shown that topoisomerase II (TOP2) plays important roles in chromosome condensation and timely separation of centromeres, little is known about its role during oocyte meiosis. Furthermore, because VP-16, which is a TOP2 inhibitor and induces DNA double strand breaks, is often used for ovarian cancer chemotherapy, its effects on oocytes must be studied for ovarian cancer patients to recover ovarian function following chemotherapy. This study showed that inhibiting TOP2 with either ICRF-193 or VP-16 during meiosis I impaired chromatin condensation, chromosome alignment, TOP2α localization and caused metaphase I (MI) arrest and first polar body (PB1) abscission failure. Inhibiting or neutralizing either spindle assembly checkpoint (SAC), Aurora B or maturation-promoting factor (MPF) significantly abolished the effect of ICRF-193 or VP-16 on MI arrest. Treatment with ICRF-193 or VP-16 significantly activated MPF and SAC but the effect disappeared when Aurora B was inhibited. Most of the oocytes matured in the presence of ICRF-193 or VP-16 were arrested at MI, and only 11% to 27% showed PB1 protrusion. Furthermore, most of the PB1 protrusions formed in the presence of ICRF-193 or VP-16 were retracted after further culture for 7 h. In conclusion, TOP2 dysfunction causes MI arrest by activating Aurora B, SAC and MPF and it prevents PB1 abscission by promoting chromatin bridges.

Transcriptomic study of the mechanism by which the Kai Yu Zhong Yu recipe improves oocyte quality in a stressed mouse model

ETHNOPHARMACOLOGICAL RELEVANCE

The Kai Yu Zhong Yu recipe (KYZY) is a classic herbal formula in traditional Chinese medicine (TCM) that has been used to treat infertility associated with psychological stress for more than three hundred years.

AIM OF THE STUDY

Psychological stress has major impacts on fertility, with variable outcomes depending on the nature, strength, and duration of the stress. Stress can directly disturb ovulation, oocyte quality, maturation, and embryo development. The aim of this study is to investigate the molecular mechanism by which KYZY improves oocyte developmental potential under psychological stress.

MATERIALS AND METHODS

ICR female mice aged 4-5 weeks were randomly divided into five groups: control, stressed in the chronic unpredictable stress model (CUSM), and stressed plus KYZY treatment at 38.2 g/kg (KYZYH), 19.1 g/kg (KYZYM), or 9.6 g/kg (KYZYL). Ovary function was assessed by measuring serum levels of estradiol (E2), luteinizing hormone (LH), follicle-stimulating hormone (FSH), and anti-Müllerian hormone (AMH). Oocyte quality was evaluated in terms of reactive oxygen species (ROS) levels, apoptotic DNA fragmentation, and mitochondria distribution. We used RNA sequencing (RNAseq) to identify differentially expressed genes (DEGs) between groups and then further analyzed the DEGs for gene ontology (GO) term enrichment and protein-protein interactions.

RESULTS

Mice in the stressed group had reduced serum E2, LH, and FSH as well as increased ROS levels, increased apoptosis, and disturbed mitochondria distribution in oocytes. Treatment with KYZY at all three doses reversed or ameliorated these negative effects of stress. DEG analysis identified 187 common genes between the two comparisons (stressed vs. control and KYZYM vs. stressed), 33 of which were annotated with six gene ontology (GO)'s biological process (BP) terms: cell differentiation, apoptosis, ATP synthesis, protein homo-oligomerization, neuron migration, and negative regulation of peptidase activity. Protein-protein interaction network analysis of DEGs identified key hub genes. Notably, the genes Atp5o and Cyc1 were both involved in the ATP synthesis and among the top three hub genes, suggesting that regulation of oocyte mitochondrial electron transport and ATP synthesis is important in the response to stress and also is a possible mechanism of action for KYZY.

CONCLUSIONS

KYZY was effective in ameliorating the adverse effects of stress on oocyte competence, possibly by targeting the mitochondrial respiratory chain and ATP synthase.

d-Leucine protects oocytes from chronic psychological stress in mice

PURPOSE

Psychological stress could negatively influence female reproductive ability. d-Leucine (d-Leu) is a d-type amino acid found in foods and mammalian tissues. We have examined the protective effects of d-Leu on oocyte abnormality induced by psychological stress.

METHODS

Female mice (6-week-old) were divided into three groups: control, restraint stress (RS), and RS/d-Leu. The RS and RS/d-Leu mice were holed for 3 hours daily during 14 days. RS/d-Leu mice were fed 0.3% d-Leu diet. The oocyte maturation failure was analyzed by shapes of spindles and chromosomes. In addition, levels of heme-oxygenase-1 (HO-1) and superoxide dismutase (SOD) expression in the ovaries were also examined. Whether d-Leu reduces the generation of reactive oxygen species (ROS) in cultured cells, K562 cells were treated with d-Leu, and then ROS in K562 were analyzed.

RESULTS

Oocyte maturation failure was increased in RS mice. d-Leu reduced abnormal oocytes to control level. The expression levels of HO-1 and SOD2 increased in RS/d-Leu mice compared to those of RS mice. ROS levels were decreased in K562 cells with d-Leu in a dose-dependent manner.

CONCLUSIONS

We concluded that d-Leu protects oocytes from psychological stress through the induction of HO-1 and SOD2 expression then by reducing oxidative stress.

Restraint stress and elevation of corticotrophin-releasing hormone in female mice impair oocyte competence through activation of the tumour necrosis factor α (TNF-α) system

Studies have observed that restraint stress (RS) and the associated elevation in corticotrophin-releasing hormone (CRH) impair oocyte competence by triggering apoptosis of ovarian cells but the underlying mechanisms are largely unclear. Although one study demonstrated that RS and CRH elevation triggered apoptosis in ovarian cells and oocytes via activating Fas/FasL signalling, other studies suggested that RS might damage cells by activating other pathways as well as Fas signalling. The objective of this study was to test whether RS and CRH elevation impairs oocytes by activating tumour necrosis factor α (TNF-α) signalling. Our invivo experiments showed that RS applied during oocyte prematuration significantly increased expression of TNF-α and its receptor (TNFR1) while inducing apoptosis in both oocytes and mural granulosa cells (MGCs). Invitro treatment of MGCs with CRH significantly increased their apoptotic percentages and levels of TNF-α and TNFR1 expression. Invitro knockdown by interfering RNA, invivo knockout of the TNF-α gene or injection of TNF-α antagonist etanercept significantly relieved the adverse effects of RS and CRH on apoptosis of MGCs and/or the developmental potential and apoptosis of oocytes. The results suggest that RS and CRH elevation in females impair oocyte competence through activating TNF-α signalling and that a TNF-α antagonist might be adopted to ameliorate the adverse effects of psychological stress on oocytes.

Review of psychological stress on oocyte and early embryonic development in female mice

Psychological stress can cause adverse health effects in animals and humans. Accumulating evidence suggests that psychological stress in female mice is associated with ovarian developmental abnormalities accompanied by follicle and oocyte defects. Oocyte and early embryonic development are impaired in mice facing psychological stress, likely resulting from hormone signalling disorders, reactive oxygen species (ROS) accumulation and alterations in epigenetic modifications, which are primarily mediated by the hypothalamic-pituitary-adrenal (HPA) and hypothalamic-pituitary-ovarian (HPO) axes. The present evidence suggests that psychological stress is increasingly becoming the most common causative factor for female subfertility. Here, we review recent progress on the impact of psychological stress on female reproduction, particularly for oocyte and early embryonic development in female mice. This review highlights the connection between psychological stress and reproductive health and provides novel insight on human subfertility.

Tandem mass tag-based proteomic analysis reveals the treatment mechanism of Bushen Huoxue Formula on psychological stress-induced premature ovarian insufficiency

ETHNOPHARMACOLOGICAL RELEVANCE

Bushen Huoxue formula (BSHXF) is a Chinese herbal prescription composed of eleven herbs widely used to treat psychological stress-induced premature ovarian insufficiency (POI) in clinical. However, the underlying mechanism is still unclear.

AIM OF THE STUDY

The purpose of this study was to clarify the underlying molecular mechanisms of BSHXF in the treatment of psychological stress-induced POI.

MATERIALS AND METHODS

The rat model was induced by corticosterone (CORT, 40mg/kg). Drugs were administered to rats once daily for 21 days. The serum E₂, FSH and AMH levels were examined by enzyme-linked immunosorbent assays. Tandem mass tag-based proteomic analysis was used to identify differentially expressed proteins. Western blot was used to verify the results of proteomic.

RESULTS

Our results indicate that BSHXF can improve ovarian disfunction. The levels of serum FSH were signally enhanced in model group compared to control group. As respected, BSHXF treatment for 3 weeks led to the decreased FSH levels than the model group. The concentrations of AMH showed an obvious decrease in the model group and were increased by BSHXF treatment. Moreover, the size and number of follicles in the BSHXF groups were similar to those in the control group. The proteomic screened out that Np4 and Angptl4 were simultaneously enriched by GO and KEGG, thus these two proteins were chosen for further study.

CONCLUSIONS

These findings revealed that BSHXF might regulate the expression of Np4 and Angptl4 to improve psychological stress-induced POI.

Melatonin protects against chronic stress-induced oxidative meiotic defects in mice MII oocytes by regulating SIRT1

Chronic stress which is common in the current society can be harmful to female reproduction and is associated with oocyte defects. However, the underlying mechanisms remain largely unknown. Herein, by using a mouse model of chronic restraint stress, we demonstrated that chronic stress could induce meiotic spindle abnormalities, chromatin misalignment, mitochondrial dysfunction and elevated ROS levels in oocytes in vivo, all of which were normalized by the administration of melatonin. Consistently, melatonin treatment during in vitro maturation also attenuated the meiotic defects induced by H₂O₂ by regulating autophagy and SIRT1, which could be abolished by SIRT1 inhibitor, Ex527 and autophagy inhibitor Bafilomycin A1 (Baf A1). These data indicate that melatonin can mitigate chronic stress-induced oxidative meiotic defects in mice MII oocytes by regulating SIRT1 and autophagy, providing new understanding for stress-related meiotic errors in MII oocytes and suggesting melatonin and SIRT1 could be new targets for optimizing culture system of oocytes as well as fertility management.

Restraint-induced corticotrophin-releasing hormone elevation triggers apoptosis of ovarian cells and impairs oocyte competence via activation of the Fas/FasL system

Mechanisms by which psychological stress damages oocytes are largely undetermined. Although a previous study showed that the stress-induced corticotrophin-releasing hormone (CRH) elevation impaired oocyte competence by triggering apoptosis of ovarian cells, how CRH causes apoptosis in ovarian cells and oocytes is unknown. In this study, we have examined the hypothesis that restraint stress (RS)-induced CRH elevation triggers apoptosis of ovarian cells and impairs oocyte competence through activating the Fas/FasL system. The results showed that RS of female mice impaired oocyte competence, enhanced expression of CRH and CRH receptor (CRH-R) in the ovary, and induced apoptosis while activating the Fas/FasL system in mural granulosa cells (MGCs) and oocytes. Injecting mice with CRH-R1 antagonist antalarmin significantly alleviated the adverse effect of RS on oocyte developmental potential. Treatment of cultured MGCs recapitulated the effects of CRH and antalarmin on apoptosis and Fas/FasL expression in MGCs. Silencing FasL gene by RNA interference in cultured MGCs further confirmed the involvement of the Fas/FasL system in the CRH triggered apoptosis of ovarian cells. It is concluded that the RS-induced CRH elevation triggers apoptosis of ovarian cells and impairs oocyte competence via activation of the Fas/FasL system.

Parental pre-conception stress status and risk for anxiety in rat offspring: specific and sex-dependent maternal and paternal effects

Prenatal stressful events have long-lasting consequences on behavioral responses of offspring. While the effects of gestational and maternal stress have been extensively studied on psychological alterations in the progeny, little is known about effects of each parent's pre-conception life events on emotional responses in offspring. Here, the effect of maternal and/or paternal pre-conception stress was investigated on anxiogenic responses of offspring. Male and female adult rats were subjected to predatory stress (contactless exposure to a cat for 1 + 1 h per day) for 50 (male, n: 12) and 15 (female, n: 24) consecutive days; controls were not exposed. After the stress procedure, the control and stressed rats were mated to create four types of breeding pairs: control female/control male, stressed female/control male, control female/stressed male, and stressed female/stressed male. On postnatal days 30-31, the offspring were tested on the elevated plus maze and plasma corticosterone concentration was measured. Half of the pups were exposed to acute predatory stress before the elevated plus maze test. In most subgroups, corticosterone and anxiety-like behaviors in the offspring with both or only one parent exposed to pre-gestational stress increased compared to their control counterparts. However, under acute stress conditions, a different sex-dependent pattern of anxiety responses emerged. The combined effects of maternal and paternal stress were not additive. Hence, individual offspring behaviors can be influenced by the former life stress experiences of either parent. Incorporation of genetic and epigenetic aspects in development of neurobehavioral abnormalities and reprograming of the hypothalamic-pituitary-adrenal axis may contribute to this phenomenon. Lay summary Early life stress (including during pregnancy) is known to have long-lasting effects on offspring, including emotional behaviors. Whether individual anxiety behaviors can be influenced by stress experiences of each parent even before a pregnancy is less well-understood. Our findings from this study on rats exposed to predator stress before mating suggest that maternal or paternal adult life events prior to pregnancy can lead to maladaptive behavior in their offspring later in life.

Influence of N-acetyl-L-cysteine against bisphenol a on the maturation of mouse oocytes and embryo development: in vitro study

BACKGROUND

Bisphenol A (BPA), an endocrine disruptor, is a widely used chemical that has adverse effects on animal development and reproduction. The current research aimed to evaluate the effect of BPA on the in vitro maturation (IVM) and subsequent embryo development of mouse oocytes following in vitro fertilization (IVF).

METHODS

IVM was performed in the presence of different concentrations (0, 20, 50, or 100 μg/mL) of BPA. Nuclear maturation, IVF efficiency and embryonic development were determined. The levels of reactive oxygen species (ROS) and glutathione (GSH) in the BPA (50 μg/mL) group were evaluated. We explored the ability of N-acetyl-L-cysteine (NAC) in the IVM medium to rescue the BPA-induced damage by examining changes in nuclear maturation, IVF rate, blastocyst formation, ROS levels and GSH content.

RESULTS

Compared with the control, BPA (50 μg/mL) supplementation during oocyte IVM significantly inhibited nuclear maturation and decreased fertilization and blastocyst formation rates. In addition, BPA exposure increased ROS levels and decreased GSH content in oocytes. The addition of NAC weakened the BPA-induced suppression of nuclear maturation, relieved the BPA-induced downregulation of the fertilization and blastocyst formation rates, and mitigated the increased ROS levels and decreased GSH content.

CONCLUSION

BPA affects mouse oocyte maturation and subsequent early embryonic developmental competence following IVF by increasing intracytoplasmic oxidative stress in mature oocytes. NAC can reduce these harmful effects to a certain extent.

Encircling granulosa cells protects against di-(2-ethylhexyl)phthalate-induced apoptosis in rat oocytes cultured in vitro

The present study investigated if the presence of encircling granulosa cells protected against di(2-ethylhexyl)phthalate (DEHP)-induced oxidative stress in rat oocytes cultured in vitro. Denuded oocytes and cumulus–oocyte complexes (COCs) were treated with or without various doses of DEHP (0.0, 25.0, 50.0, 100, 200, 400 and 800 μM) in vitro. Morphological apoptotic changes, levels of oxidative stress and reactive oxygen species (ROS), mitochondrial membrane potential, and expression levels of apoptotic markers (Bcl2, Bax, cytochrome c) were analyzed. Our results showed that DEHP induced morphological apoptotic changes in a dose-dependent manner in denuded oocytes cultured in vitro. The effective dose of DEHP (400 µg) significantly (P>0.05) increased oxidative stress by elevating ROS levels and the mitochondrial membrane potential with higher mRNA expression and protein levels of apoptotic markers (Bax, cytochrome c). Encircling granulosa cells protected oocytes from DEHP-induced morphological changes, increased oxidative stress and ROS levels, as well as increased expression of apoptotic markers. Taken together our data suggested that encircling granulosa cells protected oocytes against DEHP-induced apoptosis and that the presence of granulosa cells could act positively towards the survival of oocytes under in vitro culture conditions and may be helpful during assisted reproductive technique programmes.

Maternal Preconception Stress Alters Prefrontal Cortex Development in Long-Evans Rat Pups without Changing Maternal Care

Stress during development can shift the typical developmental trajectory. Maternal stress prior to conception has recently been shown to exert similar influences on the offspring. The present study questioned if a consistent maternal stressor prior to conception (elevated platform stress) would impact the pre-weaning development of offspring brain and behavior, and if maternal care was vulnerable to this experience. Adult female Long-Evans rats were subjected to elevated platform stress for 27 days prior to mating with non-stressed males. Maternal care was monitored, and pups were assessed in two tests of early behavioral development, negative geotaxis and open field. Pups were perfused at weaning and their brains were extracted and stained with Cresyl Violet, allowing gross measurements of cortical and subcortical structures and estimates of neuron density. Main findings indicate that a change in prefrontal cortical thickness is evident despite no change in maternal care. Female offspring show a decrease in medial-dorsal thalamus size. The current study failed to find an effect of maternal preconception stress on early behavioral development. These results suggest that the PFC, and likely behavior dependent on the PFC, is vulnerable to maternal preconception stress and that a strong sex effect is evident. Further studies should examine how such offspring fare using a lifespan model and investigate potential mechanisms responsible for these effects.

Chronic restraint stress disturbs meiotic resumption through APC/C-mediated cyclin B1 excessive degradation in mouse oocytes

Psychological stress, which exerts detrimental effects on human reproduction, may compromise the meiotic competence of oocytes. Meiotic resumption, germinal vesicle breakdown (GVBD), is the first milestone to confer meiotic competence to oocytes. In the practice of assisted reproductive technology (ART), the timing for GVBD is associated with the rates of cleavage and blastocyst formation. However, whether chronic stress compromises oocyte competence by influencing GVBD and the underlying mechanisms are unclear. In the present study, a chronic restraint stress (CRS) mouse model was used to investigate the effects of stress on oocyte meiotic resumption, as well as the mechanisms. Following a 4-week chronic restraint stress in female mice, the percentage of abnormal bipolar spindles increased and indicated compromised oocyte competence in the CRS group. Furthermore, we identified a decreased percentage of GVBD and prolonged time of GVBD in the CRS mouse oocytes compared with the control group. CRS simultaneously reduced the expression of cyclin B1 (CCNB1), which represents a regulatory subunit of M-phase/mature promoting factor (MPF). However, MG132, an inhibitor of anaphase-promoting complex/cyclosome (APC/C), could rescue the prolonged time of GVBD and increase the expression level of CCNB1 of oocytes from the CRS mice. Collectively, our results demonstrated that stress disturbed meiotic resumption through APC/C-mediated CCNB1 degradation, thus providing a novel understanding for stress-related oocyte quality decline; moreover, it may provide a non-invasive approach to select high-quality gametes and novel targets for molecular therapy to treat stress-related female infertility.

Intergenerational Transmission of Maternal Childhood Maltreatment Exposure: Implications for Fetal Brain Development

OBJECTIVE

Growing evidence suggests the deleterious consequences of exposure to childhood maltreatment (CM) not only might endure over the exposed individual's lifespan but also might be transmitted across generations. The time windows, mechanisms, and targets of such intergenerational transmission are poorly understood. The prevailing paradigm posits that mother-to-child transmission of the effects of maternal CM likely occurs after her child's birth. The authors seek to extend this paradigm and advance a transdisciplinary framework that integrates the concepts of biological embedding of life experiences and fetal origins of health and disease risk.

METHOD

The authors posit that the period of embryonic and fetal life represents a particularly sensitive time for intergenerational transmission; that the developing brain represents a target of particular interest; and that stress-sensitive maternal-placental-fetal biological (endocrine, immune) pathways represent leading candidate mechanisms of interest.

RESULTS

The plausibility of this model is supported by theoretical considerations and empirical findings in humans and animals. The authors synthesize several research areas and identify important knowledge gaps that might warrant further study.

CONCLUSION

The scientific and public health relevance of this effort relates to achieving a better understanding of the "when," "what," and "how" of intergenerational transmission of CM, with implications for early identification of risk, prevention, and intervention.

MALDI mass spectrometry reveals that cumulus cells modulate the lipid profile of in vitro-matured bovine oocytes

The influence of cumulus cells (CC) on the lipid profile of bovine oocytes matured in two different lipid sources was investigated. Cumulus-oocyte complexes (COC) or denuded oocytes (DO) were matured in tissue culture medium (TCM) supplemented with fetal bovine serum (FBS) or serum substitute supplement (SSS). Lipid profiles of TCM, serum supplements, immature CC and oocyte (IO), and in vitro-matured oocytes from COC and DO were then analyzed by matrix assisted laser desorption ionization mass spectrometry (MALDI-MS) and submitted to partial least squares-discriminant analysis (PLS-DA). The developmental competence of such oocytes was also assessed. Differences in lipid composition were observed between two types of sera and distinctly influenced the lipid profile of CC. As revealed by PLS-DA, the abundance of specific ions corresponding to triacylglycerols (TAG) or phospholipids (PL) were higher in COC compared to DO both supplemented with FBS or SSS and to some extent affected the subsequent DO in vitro embryo development. DO exposed to SSS had however a marked diminished ability to develop to the blastocyst stage. These results indicate a modulation by CC of the oocyte TAG and PL profiles associated with a specific cell response to the serum supplement used for in vitro maturation.

Primordial germ cell differentiation of nuclear transfer embryonic stem cells using surface modified electroconductive scaffolds

A combination of nanotopographical cues and surface modification of collagen and fibronectin is a potential platform in primordial germ cells (PGCs) differentiation. In the present study, the synergistic effect of nanotopography and surface modification on differentiation of nuclear transfer embryonic stem cells (nt-ESCs) toward PGC lineage was investigated. In order to achieve this goal, poly-anyline (PANi) was mix within poly-L-lactic acid (PLLA). Afterward, the random composite mats were fabricated using PLLA and PANi mix solution. The nanofiber topography notably upregulated the expressions of prdm14, mvh and c-kit compared with tissue culture polystyrene (TCP). Moreover, the combination of nanofiber topography and surface modification resulted in more enhancement of PGCs differentiation compared with non-modified nanofibrous scaffold. Additionally, gene expression results showed that mvh and c-kit were expressed at higher intensity in cells exposed to collagen and fibronectin rather than collagen or fibronectin solitary. These results demonstrated the importance of combined effect of collagen and fibronectin in order to develop a functional extracellular matrix (ECM) mimic in directing stem cell fate and the potential of such biofunctional scaffolds for treatment of infertility.

Melatonin implantation improved the egg-laying rate and quality in hens past their peak egg-laying age

The egg-laying rates of hens approximately 470 days of age exhibited a positive correlation to blood melatonin levels. The hens with an egg-laying rate <30%, 30~90% and ≥90% had blood melatonin levels of 5.8 ± 2.6, 74.0 ± 32.9 and 445.9 ± 115.3 ng/ml, respectively. When 10 mg of melatonin was implanted into the hens at 300, 360, 470 and 550 days of age, the egg-laying rates increased 4.63 ± 0.46%, 8.38 ± 1.45%, 4.93 ± 0.85% and 7.93 ± 0.91%, respectively, compared to that of the controls. Melatonin implantation in hens at 300–470 days of age was observed to enhance egg production and reduce the rate of appearance of sharpei eggs. Melatonin (10 mg) implanted in hens 360 days of age did not influence the blood levels of progesterone (P4) or the gene expression levels of ovarian follicle stimulating hormone receptor (FSHR), luteinizing hormone receptor (LHR), oestradiol receptor alpha (ERα), superoxide dismutase 2 (SOD2) or melatonin receptor 1 (MT1). In contrast, melatonin significantly elevated the serum oestradiol-17β (E2) content, down-regulated the gene expression of gonadotropin-inhibitory hormone receptor (GnIHR), and enhanced the expression of melatonin receptor 2 (MT2). This result indicates that the improved egg-laying rate by melatonin was the result of increased serum oestradiol and decreased ovarian GnIHR. These alterations may be mediated by MT2 activation.

Parental life events cause behavioral difference among offspring: Adult pre-gestational restraint stress reduces anxiety across generations

While effects of gestational, neonatal or adolescent stress on psychological alterations in progeny have been extensively studied, much less is known regarding the effects of adult pre-gestational life events on offspring behavior. Although full siblings often display behavioral differences, whether the different parental life events prior to different pregnancies contribute to these behavioral differences among siblings is worth studying. In this study, male and female adult mice were restrained for 60 days before mating with unstressed or stressed partners. F1 offspring were examined for anxiety or mated to generate F2. Both F1 females and males from restrained mothers and/or fathers showed significantly reduced anxiety and serum cortisol and increased mRNA levels of glucocorticoid receptor and brain-derived neurotrophic factor compared to control offspring from unstressed parents. Similar behavioral and molecular changes were also observed in F2 females and males. Although restraint of adolescent mice reduced anxiety in F1 of both sexes, social instability of them increased anxiety predominantly in F1 females. Thus, adult pre-gestational restraint reduced offspring’s anxiety across generations; different stressors on parents may cause different phenotypes in offspring; individual behaviors can depend on adult life experiences of parents.

Oxidative Stress Induces Mouse Follicular Granulosa Cells Apoptosis via JNK/FoxO1 Pathway

The c-Jun N-terminal protein kinase (JNK) plays an important role in the regulation of cell apoptosis. Forkhead box O (FoxO) transcription factors are involved in diverse biological processes, including cellular metabolism, cell apoptosis, and cell cycle. However, the JNK/FoxO1 pathway involved in the process of apoptosis induced by oxidative stress remains to be elucidated. Here, we demonstrated that the JNK activity significantly increased in response to oxidative stress in mouse follicular granulosa cells (MGCs). SP600125, a selective JNK inhibitor, attenuated the oxidative stress-induced MGCs apoptosis. Oxidative stress enhanced the FoxO1 nuclear translocation by activating the JNK activity. Moreover, JNK mediated the dissociation of FoxO1 from 14-3-3 proteins in MGCs after the treatment with H₂O₂. Finally, oxidative stress up-regulated the expression of FoxO1 via JNK mediation of FoxO1 self-regulation in MGCs. Taken together, our findings suggest that JNK/FoxO1 is involved in the regulation of oxidative stress-induced cell apoptosis in MGCs.

Progesterone influences cytoplasmic maturation in porcine oocytes developing in vitro

Progesterone (P4), an ovarian steroid hormone, is an important regulator of female reproduction. In this study, we explored the influence of progesterone on porcine oocyte nuclear maturation and cytoplasmic maturation and development in vitro. We found that the presence of P4 during oocyte maturation did not inhibit polar body extrusions but significantly increased glutathione and decreased reactive oxygen species (ROS) levels relative to that in control groups. The incidence of parthenogenetically activated oocytes that could develop to the blastocyst stage was higher (p < 0.05) when oocytes were exposed to P4 as compared to that in the controls. Cell numbers were increased in the P4-treated groups. Further, the P4-specific inhibitor mifepristone (RU486) prevented porcine oocyte maturation, as represented by the reduced incidence (p < 0.05) of oocyte first polar body extrusions. RU486 affected maturation promoting factor (MPF) activity and maternal mRNA polyadenylation status. In general, these data show that P4 influences the cytoplasmic maturation of porcine oocytes, at least partially, by decreasing their polyadenylation, thereby altering maternal gene expression.

Blood plasma collected after adrenocorticotropic hormone administration during the preovulatory period in the sow negatively affects in vitro fertilization by disturbing spermatozoa function

Successful fertilization is essential for reproduction and might be negatively affected by stressful events, which could alter the environment where fertilization occurs. The aim of the study was to determine whether an altered hormonal profile in blood plasma caused by adrenocorticotropic hormone (ACTH) administration could affect in vitro fertilization in the pig model. In experiment 1, gametes were exposed for 24 hours to plasma from ACTH-treated, non-ACTH-treated sows, or medium with BSA. Fertilization, cleavage, and blastocyst rates were lower in the ACTH group compared with the no ACTH or BSA control groups (P < 0.01). In experiment 2, the exposure of matured oocytes for 1 hour before fertilization to the same treatments did not have an impact on their ability to undergo fertilization or on embryo development. In experiment 3, spermatozoa were incubated for 0, 1, 4, and 24 hours under the same conditions. There was no effect of treatment on sperm viability. The percentage of acrosome-reacted spermatozoa remained higher in the ACTH group compared with the non-ACTH-treated group through the incubation period (P < 0.001). Protein tyrosine phosphorylation (PTP) patterns were also affected by treatment (P < 0.001). The presence of an atypical PTP pattern was higher in the ACTH group at all the analyzed time points compared with the BSA and no ACTH groups (P < 0.001). In conclusion, this altered environment may not affect oocyte competence but might affect the sperm fertilizing ability through alterations in the acrosome reaction and correct sequence of PTP patterns.

Antioxidant supplementation overcomes the deleterious effects of maternal restraint stress-induced oxidative stress on mouse oocytes

In this study, using a mouse model, we tested the hypothesis that restraint stress would impair the developmental potential of oocytes by causing oxidative stress and that antioxidant supplementation could overcome the adverse effect of stress-induced oxidative stress. Female mice were subjected to restraint stress for 24 h starting 24 h after equine chorionic gonadotropin injection. At the end of stress exposure, mice were either killed to recover oocytes forin vitromaturation (IVM) or injected with human chorionic gonadotropin and caged with male mice to observein vivodevelopment. The effect of antioxidants was testedin vitroby adding them to IVM medium orin vivoby maternal injection immediately before restraint stress exposure. Assays carried out to determine total oxidant and antioxidant status, oxidative stress index, and reactive oxygen species (ROS) and glutathione levels indicated that restraint stress increased oxidative stress in mouse serum, ovaries, and oocytes. Whereas the percentage of blastocysts and number of cells per blastocyst decreased significantly in oocytes from restraint-stressed mice, addition of antioxidants to IVM medium significantly improved their blastocyst development. Supplementation of cystine and cysteamine to IVM medium reduced ROS levels and aneuploidy while increasing glutathione synthesis and improving pre- and postimplantation development of oocytes from restraint-stressed mice. Furthermore, injection of the antioxidant epigallocatechin gallate into restraint-stressed mice significantly improved the blastocyst formation and postimplantation development of their oocytes. In conclusion, restraint stress at the oocyte prematuration stage impaired the developmental potential of oocytes by increasing oxidative stress and addition of antioxidants to IVM medium or maternal antioxidant injection overcame the detrimental effect of stress-induced oxidative stress. The data reported herein are helpful when making attempts to increase the chances of a successful outcome in human IVF, because restraint was applied at a stage similar to the FSH stimulation period in a human IVF program.