Follicular atresia in the prepubertal spiny mouse (Acomys cahirinus) ovary

Paeoniflorin Promotes Ovarian Development in Mice by Activating Mitophagy and Preventing Oxidative Stress

During the development of animal organs, various adverse stimuli or toxic environments can induce oxidative stress and delay ovarian development. Paeoniflorin (PF), the main active ingredient of the traditional Chinese herb Paeonia lactiflora Pall., has protective effects on various diseases by preventing oxidative stress. However, the mechanism by which PF attenuates oxidative damage in mouse ovaries remains unclear. We evaluated the protective effects of PF on ovaries in an H2O2-induced mouse oxidative stress model. The H2O2-induced mouse ovarian oxidative stress model was used to explore the protective effect of PF on ovarian development. Histology and follicular development were observed. We then detected related indicators of cell apoptosis, oxidative stress, and autophagy in mouse ovaries. We found that PF inhibited H2O2-induced ovarian cell apoptosis and ferroptosis and promoted granulosa cell proliferation. PF prevented oxidative stress by increasing nuclear factor erythroid 2-related factor 2 (Nrf2) and heme oxygenase-1 (HO-1) expression levels. In addition, the autophagic flux of ovarian cells was activated and was accompanied by increased lysosomal biogenesis. Moreover, PF-mediated autophagy was involved in clearing mitochondria damaged by H2O2. Importantly, PF administration significantly increased the number of primordial follicles, primary follicles, secondary follicles, and antral follicles. PF administration improved ovarian sizes compared with the H2O2 group. The present study suggested that PF administration reversed H2O2-induced ovarian developmental delay and promoted follicle development. PF-activated mitophagy is crucial for preventing oxidative stress and improving mitochondrial quality.

Activation of interleukin 33-NFκB axis in granulosa cells during atresia and its role in disposal of atretic follicles†

It has been previously shown that the cytokine interleukin 33 is required for two processes, i.e., autophagic digestion of granulosa cells and recruitment of macrophages into atretic follicles, for full disposal of atretic follicles. Now, this study shows that activation of interleukin 33-suppression of tumorigenicity 2-Nuclear Factor ĸB (NFκB) axis in granulosa in early atretic follicles may regulate those two events. Injection of human chorionic gonadotropin has been shown to induce a transient peak of interleukin 33 expression with synchronized atresia. In this model, interleukin 33-independent expression of suppression of tumorigenicity 2 in granulosa cells was detected in early atretic follicles before macrophage invasion. The activation of NFκB pathway in ovaries was further demonstrated in vivo in Tg mice with luciferase-reporter for NFκB activation; the activation was microscopically localized to granulosa cells in early atretic follicles. Importantly, antibody blockage of interleukin 33 or interleukin 33 Knock-out (KO) (Il33-/-) not only inhibited NFκB activity in ovaries, but it also altered expression of two key genes, i.e., reduction in proinflammatory interleukin6 (IL6) expression, and a surge of potential autophagy-inhibitory mammalian target of rapamycin (mTOR) expression in atretic follicles. By contrast, apoptosis and other genes, such as interleukin1β (IL1β) were not affected. In conclusion, in parallel to apoptosis, atresia signals also trigger activation of the interleukin 33-suppression of tumorigenicity 2-NFκB pathway in granulosa, which leads to (1) down-regulated expression of mTOR that is a negative regulator of autophagy and (2) up-regulated expression of proinflammatory IL6.

Neurotrophin-4 promotes in vitro development and maturation of human secondary follicles yielding metaphase II oocytes and successful blastocyst formation

STUDY QUESTION

Does a matrix-free culture system supplemented with neurotrophic factor 4 (NT4) improve human in vitro follicular development and meiotic maturation, ultimately resulting in fertilizable oocytes?

SUMMARY ANSWER

NT4 supplementation of in vitro culture significantly enhances the growth, steroid hormone production, and maturity potential of human secondary follicles derived from fresh ovarian medulla (from post- and pre-pubertal patients), thereby yielding fertilizable oocytes.

WHAT IS KNOWN ALREADY

Reconstituting folliculogenesis in vitro is of paramount importance in the realms of fertility preservation, reproductive biology research, and reproductive toxicity assessments. However, the efficiency of in vitro culture systems remains suboptimal, as the attainment of fertilizable oocytes from in vitro growth (IVG) of human follicles remains unachieved, with the data being particularly scant regarding follicles from prepubertal girls. We have previously found that mouse oocytes from secondary follicles derived from IVG are deficient in neuroendocrine regulation. NT4 and its corresponding receptor have been identified in human follicles. Significantly, the addition of NT4 during the IVG process markedly enhances both follicle growth and oocyte maturation rates in mice.

STUDY DESIGN SIZE DURATION

Fresh medulla tissue obtained during tissue preparation for ovarian tissue cryopreservation (OTC) were collected from 10 patients aged from 6 to 21 years old, all of whom had undergone unilateral oophorectomy as a means of fertility preservation. Isolated secondary follicles were individually cultured in vitro with or without NT4 in a matrix-free system.

PARTICIPANTS/MATERIALS SETTING METHODS

Secondary follicles, extracted via enzymatic digestion and mechanical disruption from each patient, were randomly allocated to either a control group or an NT4-supplemented group (100 ng/ml), followed by individual culture on an ultra-low attachment plate. Follicle growth and viability were assessed by microscopy. Levels of anti-Müllerian hormone (AMH), estradiol, and progesterone in the medium were quantified. An oocyte-specific marker was identified using confocal fluorescence microscopy following DEAD box polypeptide 4 (DDX4) staining. The competence of individual oocytes for maturation and fertilization were assessed after IVM and ICSI with donated sperm samples.

MAIN RESULTS AND THE ROLE OF CHANCE

Overall, isolated follicles from both groups survived up to 6 weeks with increasing diameters over the duration (P < 0.05), reaching terminal diameters of almost 1 mm with confirmed steroidogenesis and expression of oocyte marker (DDX4), and producing morphologically normal MII oocytes. When compared with the control group, the NT4 group had a similar initial follicular diameter (206 ± 61.3 vs 184 ± 93.4 μm) but exhibited a significant increase in follicular diameter from the ninth day of culture onwards (P < 0.05). From Week 3, estradiol and progesterone production were significantly increased in the NT4 group, while no significant difference was observed in AMH production between groups. The proportion of 'fast-growth' follicles in the NT4 group was significantly higher than that in the control group (13/23 vs 6/24, P < 0.05). An increased efficiency of MII oocyte maturation per live follicle in the NT4 group was also observed (control group vs NT4 group, 4/24 vs 10/23, P < 0.05). It is noteworthy that an MII oocyte obtained from the control group exhibited abnormal fertilization after ICSI. In contrast, an MII oocyte acquired from the NT4 group progressed to the blastocyst stage and showed potential for transfer.

LARGE SCALE DATA

N/A.

LIMITATIONS REASONS FOR CAUTION

The cohort examined in this study was all patients diagnosed with beta-thalassemia major. Whether this culture system is effective for patients with other diseases remains unknown. Since the chosen dose of NT4 was established based on dose finding in mice, the optimal dose for use in a human IVG system needs further confirmation. The oocytes and embryos procured from this study have not been quantified for ploidy status or epigenetic signatures.

WIDER IMPLICATIONS OF THE FINDINGS

Fresh medulla tissue obtained during tissue preparation for OTC may serve as a precious source of fertilizable oocytes for female fertility preservation, even for pre-pubertal girls, without the threat of tumour reintroduction. After further characterization and optimization of the system, this culture system holds the potential to provide a powerful future research tool, for the comprehensive exploration of human follicular development mechanisms and for conducting reproductive toxicity evaluations.

STUDY FUNDING/COMPETING INTERESTS

This work was supported by the National Key R&D Program of China (grant number 2022YFC2703000) and National Natural Science Foundation of China (grant numbers 82271651 and 81871214). The medium used in human follicle in vitro culture in this study has been applied for a national invention patent in China (No. 202211330660.7). The inventors of the patent, in order, are: Y.G., C.F., and X.L.

METTL3-mediated m6A methylation regulates granulosa cells autophagy during follicular atresia in pig ovaries

Follicular atresia is a normal physiological event in mammals, yet its mechanism remains to be studied. Granulosa cell (GC) autophagy is closely associated with follicular atresia. The N6-methyladenosine (m6A) modification is the most common post-transcriptional modification in eukaryotes, but its role in follicular atresia is still unknown. In this study, the possible relationship amongst follicular atresia, GC autophagy and m6A modification was studied. Our results showed that the level of autophagy in GCs increased with the degree of follicle atresia, whereas the overall m6A level decreased. Rapamycin treatment induced atresia in vitro cultured follicles, whereas 3-Methyladenine inhibited follicular atresia. Progressed atretic follicle (PAF) GCs had significantly lower METTL3 levels and significantly higher FTO levels than healthy follicle (HF) GCs. Differential gene expression analysis of GCs in PAF and HF by RNA sequencing was showed that the autophagy-related genes ULK1, ULK2, ATG2A, and ATG2B were significantly elevated in the PAF. In cultured GCs, overexpression of METTL3 significantly decreased the mRNA level of ULK1, as well as the autophagy level, whereas knockdown of METTL3 by RNAi significantly increased the mRNA level of ULK1, as well as the autophagy level. Our results indicate that m6A modification can regulate autophagy in GCs and play a role in the process of porcine follicular atresia.

PHB2 binds to ERβ to induce the autophagy of porcine ovarian granulosa cells through mTOR phosphorylation

Autophagy of ovarian granulosa cells is one of the reasons which results in follicular atresia. PHB2 regulates many fundamental biological processes and is pivotal in the mitophagy of cells; nevertheless, the autophagy in the porcine ovary and how PHB2 regulates the follicular cells are unknown. Here we report a protein complex that induces autophagy in porcine granulosa cells (PGCs) through the direct interaction of ERβ and PHB2. In this study, we aimed to elucidate the autophagy and the role of PHB2 in porcine ovaries using porcine primary ovarian granulosa cells (PGCs). The results showed that PHB2 induces PGCs autophagy because of the change in related genes and protein expression levels. In addition, the results of Co-IP and the distribution of the combination of PHB2 and ERβ showed that this complex is also indicated as an essential role of PHB2 in PGCs autophagy. Based on our results, it can be concluded that PHB2 combined with ERβ induces PGCs autophagy by targeting the mTOR pathway. This study pinpoints a novel regulatory mechanism of autophagy and demonstrates the existence of a protein complex that may underlie its roles in autophagy in PGCs.

1α,25(OH)2D3 Promotes the Autophagy of Porcine Ovarian Granulosa Cells as a Protective Mechanism against ROS through the BNIP3/PINK1 Pathway

Vitamin D (VD) is one of the important nutrients required by livestock; however, VD deficiency is reported to be widespread. Earlier studies have suggested a potential role for VD in reproduction. Studies on the correlation between VD and sow reproduction are limited. The aim of the current study was aimed to determine the role of 1,25-dihydroxy vitamin D₃ (1α,25(OH)₂D₃) on porcine ovarian granulosa cells (PGCs) in vitro to provide a theoretical basis for improving the reproductive efficiency of sows. We used chloroquine (autophagy inhibitor) and reactive oxygen species (ROS) scavenger N-acetylcysteine in conjunction with 1α,25(OH)₂D₃ to explore the effect on PGCs. The results showed that 10 nM of 1α,25(OH)₂D₃ increased PGC viability and ROS content. In addition, 1α,25(OH)₂D₃ induces PGC autophagy according to the gene transcription and protein expression levels of LC3, ATG7, BECN1, and SQSTM1 and promotes the generation of autophagosomes. 1α,25(OH)₂D₃-induced autophagy affects the synthesis of E₂ and P₄ in PGCs. We investigated the relationship between ROS and autophagy, and the results showed that 1α,25(OH)₂D₃-induced ROS promoted PGC autophagy. The ROS-BNIP3-PINK1 pathway was involved in PGC autophagy induced by 1α,25(OH)₂D₃. In conclusion, this study suggests that 1α,25(OH)₂D₃ promotes PGC autophagy as a protective mechanism against ROS via the BNIP3/PINK1 pathway.

Bone marrow mesenchymal stem cells in premature ovarian failure: Mechanisms and prospects

Premature ovarian failure (POF) is a common female reproductive disorder and characterized by menopause, increased gonadotropin levels and estrogen deficiency before the age of 40 years old. The etiologies and pathogenesis of POF are not fully clear. At present, hormone replacement therapy (HRT) is the main treatment options for POF. It helps to ameliorate perimenopausal symptoms and related health risks, but can't restore ovarian function and fertility fundamentally. With the development of regenerative medicine, bone marrow mesenchymal stem cells (BMSCs) have shown great potential for the recovery of ovarian function and fertility based on the advantages of abundant sources, high capacity for self-renewal and differentiation, low immunogenicity and less ethical considerations. This systematic review aims to summarize the possible therapeutic mechanisms of BMSCs for POF. A detailed search strategy of preclinical studies and clinical trials on BMSCs and POF was performed on PubMed, MEDLINE, Web of Science and Embase database. A total of 21 studies were included in this review. Although the standardization of BMSCs need more explorations, there is no doubt that BMSCs transplantation may represent a prospective therapy for POF. It is hope to provide a theoretical basis for further research and treatment for POF.

Identification and Validation of Autophagy-Related Genes in Primary Ovarian Insufficiency by Gene Expression Profile and Bioinformatic Analysis

Background

To investigate the relationship between primary ovarian insufficiency and autophagy, we detected and got the expression profile of human granulosa cell line SVOG, which was with or without LPS induced. The expression profile was analyzed with the focus on the autophagy genes, among which hub genes were identified.

Results

Totally, 6 genes were selected as candidate hub genes which might correlate with the process of primary ovarian insufficiency. The expression of hub genes was then validated by quantitative real-time PCR and two of them had significant expression change. Bioinformatics analysis was performed to observe the features of hub genes, including hub gene-RBP/TF/miRNA/drug network construction, functional analysis, and protein-protein interaction network. Pearson's correlation analysis was also performed to identify the correlation between hub genes and autophagy genes, among which there were four autophagy genes significantly correlated with hub genes, including ATG4B, ATG3, ATG13, and ULK1.

Conclusion

The results indicated that autophagy might play an essential role in the process and underlying molecular mechanism of primary ovarian insufficiency, which was revealed for the first time and may help to provide a molecular foundation for the development of diagnostic and therapeutic approaches for primary ovarian insufficiency.

Aging conundrum: A perspective for ovarian aging

Progressive loss of physiological integrity and accumulation of degenerative changes leading to functional impairment and increased susceptibility to diseases are the main features of aging. The ovary, the key organ that maintains female reproductive and endocrine function, enters aging earlier and faster than other organs and has attracted extensive attention from society. Ovarian aging is mainly characterized by the progressive decline in the number and quality of oocytes, the regulatory mechanisms of which have yet to be systematically elucidated. This review discusses the hallmarks of aging to further highlight the main characteristics of ovarian aging and attempt to explore its clinical symptoms and underlying mechanisms. Finally, the intervention strategies related to aging are elaborated, especially the potential role of stem cells and cryopreservation of embryos, oocytes, or ovarian tissue in the delay of ovarian aging.

Cumulus Cell DNA Damage as an Index of Human Oocyte Competence

The determination of oocyte quality is crucial for achieving effective syngamy post-sperm injection and embryonic development. Cumulus cells (CCs) have been proposed as biomarkers of oocyte quality because of their close bio-dynamic relationship with the oocyte. To determine the quality of the oocyte, CCs were sampled during oocyte preparation for ICSI to determine a CC DNA fragmentation index (CCDFI) of each individual oocyte using a variant of the chromatin dispersion test. One hundred and thirty oocytes were selected and studied from two Spanish fertility clinics, 90 of which were fertilized and developed to embryos. Significant differences were found between the CCDFI of unfertilized and fertilized oocytes (p < .001) and between the CCDFI of embryos that were discarded and those that developed suitable for transfer or cryopreservation (p < .001). Oocyte quality was negatively correlated with CCDFI (Spearman’s rho =  − 0.45; p < .001). Receiver operator characteristics curves (ROC) suggested that a cut-off value of 24% CCDFI was able to discriminate the capacity of the gametes to result in syngamy with a sensitivity and specificity of 75.6% and 65%, respectively. This cut-off supports the application of CCDFI as potential index for the evaluation of the reproductive potential of oocytes prior to fertilization.

Melatonin Represses Mitophagy to Protect Mouse Granulosa Cells from Oxidative Damage

Various environmental stimuli, including oxidative stress, could lead to granulosa cell (GC) death through mitophagy. Recently, it was reported that melatonin (MEL) has a significant effect on GC survival during oxidative damage. Here, we found that MEL inhibited oxidative stress-induced mitophagy to promote GC survival. The loss of cell viability upon H₂O₂ exposure was significantly restored after MEL treatment. Concomitantly, MEL inhibited the activation of mitophagy during oxidative stress. Notably, blocking mitophagy repressed GC death caused by oxidative stress. However, MEL cannot further restore viability of cells treated with mitophagy inhibitor. Moreover, PTEN-induced putative kinase 1 (PINK1), a mitochondrial serine/threonine-protein kinase, was inhibited by MEL during oxidative stress. As a result, the E3 ligase Parkin failed to translocate to mitochondria, leading to impaired mitochondria clearance. Using RNAi to knock down PINK1 expression, we further verified the role of the MEL-PINK1-Parkin (MPP) pathway in maintaining GC survival by suppressing mitophagy. Our findings not only clarify the protective mechanisms of MEL against oxidative damage in GCs, but also extend the understanding about how circadian rhythms might influence follicles development in the ovary. These findings reveal a new mechanism of melatonin in defense against oxidative damage to GCs by repressing mitophagy, which may be a potential therapeutic target for anovulatory disorders.

Guizhi Fuling Wan reduces autophagy of granulosa cell in rats with polycystic ovary syndrome via restoring the PI3K/AKT/mTOR signaling pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Guizhi Fuling Wan (GFW) is a traditional Chinese medicine used to remove blood stasis and dissipate phlegm for treating gynecological diseases that was invented by Zhang Zhongjing in the Eastern Han dynasty. In recent years, GFW has been widely used to treat patients with polycystic ovary syndrome (PCOS). Clinical and animal studies have shown that it is effective in the treatment of PCOS, but its mechanism is unknown. Generally, it works by regulating autophagy via the PI3K/AKT/mTOR signaling pathway.

AIM OF THE STUDY

This study investigated the effects and mechanism of GFW in PCOS rats with insulin resistance (IR) in order to provide better understanding of its observed clinical effects and a theoretical basis for the study of traditional Chinese medicine.

MATERIALS AND METHODS

Eighty-four female Sprague-Dawley rats were randomly divided into seven groups (n = 12 per group): 1) control, 2) PCOS model, 3) low-dose GFW, 4) medium-dose GFW, 5) high-dose GFW, 6) metformin, and 7) medium-dose GFW plus LY294002. In all non-control groups, we induced PCOS through daily letrozole combined with intragastric high-fat emulsion for 21 days. After treatment, rats were sacrificed and serum follicle-stimulating hormone (FSH), testosterone (T), progesterone, luteinizing hormone (LH), 17β-estradiol, fasting insulin (FINS), and fasting plasma glucose levels were measured by enzyme-linked immunosorbent assay (ELISA). The LH/FSH ratios and HOMA-IR values were calculated. Ovarian morphology was observed by hematoxylin and eosin staining, and all follicles were counted under a microscope. MDC-positive vesicles were used as markers to detect autophagy, and the expression levels of p62, Beclin1, and LC3-II were examined by immunostaining. Western blotting was used to measure PI3K/AKT/mTOR pathway activation, granulosa cell apoptosis, and autophagy.

RESULTS

Compared with the PCOS model group, GFW-treated rats had less atretic and cystic follicles, and more mature follicles and corpus lutea. The GFW-treated rats had lower serum T, LH, and FINS levels than the PCOS model group, as well as lower LH/FSH ratios and HOMA-IR values. GFW treatment resulted in significantly reduced levels of cleaved-Caspase-3, cleaved-Caspase-9, BAX, Beclin1, Atg5, and LC3-II. Phosphorylation of PI3K, AKT, and mTOR was significantly higher in GFW-treated rats compared with the PCOS model group. The phosphorylation of PI3K, AKT, and mTOR was decreased with the use of a PI3K antagonist.

CONCLUSIONS

Our results indicate that GFW inhibited granulosa cell autophagy and promoted follicular development to attenuate ovulation disorder in PCOS-IR rats. This was associated with activation of the PI3K/AKT/mTOR signaling pathway.

Environmentally relevant mixtures of phthalates and phthalate metabolites differentially alter the cell cycle and apoptosis in mouse neonatal ovaries†

Phthalates are a group of chemicals used as additives in various consumer products, medical equipment, and personal care products. Phthalates and their metabolites are consistently detected in humans, indicating widespread and continuous exposure to multiple phthalates. Thus, environmentally relevant mixtures of phthalates and phthalate metabolites were investigated to determine the effects of phthalates on the function of the ovary during the neonatal period of development. Neonatal ovaries from CD-1 mice were cultured with dimethyl sulphoxide (DMSO; vehicle control), phthalate mixture (0.1-100 μg/mL), or phthalate metabolite mixture (0.1-100 μg/mL). The phthalate mixture was composed of 35% diethyl phthalate, 21% di(2-ethylhexyl) phthalate, 15% dibutyl phthalate, 15% diisononyl phthalate, 8% diisobutyl phthalate, and 5% benzylbutyl phthalate. The phthalate metabolite mixture was composed of 37% monoethyl phthalate, 19% mono(2-ethylhexyl) phthalate, 15% monobutyl phthalate, 10% monoisononyl phthalate, 10% monoisobutyl phthalate, and 8% monobenzyl phthalate. After 96 h of culture, ovaries were harvested for histological analysis of folliculogenesis, gene expression analysis of cell cycle and apoptosis regulators, and immune staining for cell proliferation and apoptosis. The metabolite mixture significantly decreased the number and percentage of abnormal follicles (100 μg/mL) compared to controls. The metabolite mixture also significantly increased the expression of cell cycle inhibitors (100 μg/mL) and the antiapoptotic factor Bcl2l10 (10 μg/mL) compared to controls. The phthalate mixture did not significantly alter gene expression or follicle counts, but ovaries exposed to the phthalate mixture (0.1 μg/mL) exhibited marginally significantly increased apoptosis as revealed by DNA fragmentation staining. Overall, these data show that parent phthalates and phthalate metabolites differentially impact ovarian function.

miRNA-21-3p targeting of FGF2 suppresses autophagy of bovine ovarian granulosa cells through AKT/mTOR pathway

It is widely thought that the main reason for ovarian follicular atresia is apoptosis of granulosa cells, however, accumulating evidence suggests that autophagy plays a role in the fate of granulosa cells. Although epigenetic regulation including miR-21-3p associated with autophagy process has been reported in many cancer types, nevertheless, the mechanism of miR-21-3p in bovine ovary is poorly understood. In the present study, bovine ovarian granulosa cells (BGCs) were used as a model to elucidate the autophagy and role of miR-21-3p in a cattle ovary. The results from gene expression and tagged autophagosomes showed the autophagy in BGCs and miR-21-3p was identified as an important miRNA regulating autophagy of BGCs. The current results indicated that FGF2 was a validated target of miR-21-3p in autophagy regulation of BGCs according to the results from FGF2 luciferase reporter assays and FGF2 overexpression (oe-FGF2) or small interference (si-FGF2). Transfection of miR-21-3p mimic and si-FGF2 plasmids resulted in decreasing phosphorylated AKT and mTOR, while transfection of miR-21-3p inhibitor and oe-FGF2 increased the phosphorylated level of AKT and mTOR in BGCs. These data indicate that regulation of miR-21-3p on BGCs autophagy through AKT/mTOR pathway. In summary, this study suggests that miR-21-3p targets FGF2 to inhibit BGCs autophagy by repressing AKT/mTOR signaling.

Study on follicular fluid metabolomics components at different ages based on lipid metabolism

BACKGROUND

Follicular fluid is an important external environment for the growth and development of oocytes. A thorough identification of specific components in follicular fluid can better the existing understand of intracellular signal transduction and reveal potential biomarkers of oocyte health in women undergoing assisted reproductive therapy. To study on follicular fluid metabolomics components at different ages based on lipid metabolism, we have adopted a new method of SWATH to MRM(the sequential window acquisition of all theoretical fragment-ion spectra to multiple reaction monitor)metabolomics to provide extensive coverage and excellent quantitative data. This was done to investigate the differences in follicular fluid of patients undergoing in vitro fertilization (IVF) and embryo transfer in different age groups and to further explore the relationship between follicular fluid, age and reproductive function.

METHOD

A combination of Ultra-high-performance liquid chromatography and high resolution mass spectrometry techniques were used to analyze the follicular fluid of 230 patients enrolled for the IVF cycle. The patients were of different ages grouped into two groups:the younger and older patients.The obtained multidimensional chromatographic data were processed by principal component analysis (PCA) and partial least squares discriminant analysis (PLS-DA). The charge ratios and mass numbers enabled for the identification of different fragments in the samples. Matching information obtained through database search and the fragment information obtained by fragment ion scan structurally identified substances in the samples. This was used to determine the differential compounds.

RESULTS

The quality of oocytes decline with age,and the lipid composition in follicular fluid also changes,The lipid metabolism that changes with age may be related to the quality of oocytes.The main differences were in lipid metabolites. Some were up-regulated: Arachidonate, LysoPC(16:1), LysoPC(20:4) and LysoPC(20:3) while others were down-regulated: LysoPC(18:3) and LysoPC(18:1).

CONCLUSIONS

Metabolomic analysis of follicular fluid revealed that with the increase in age, several differential metabolites are at play. Among these metabolites, lipid metabolism undergoes significant changes that affect the development of oocytes thus causing reduced fertility in older women. These differential metabolites related to follicular development may provide possible detection and treatment targets for promoting oocyte health, and provide scientific basis for understanding the environment of oocyte development.

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.

Model systems for regeneration: the spiny mouse, Acomys cahirinus

The spiny mouse, Acomys spp., is a recently described model organism for regeneration studies. For a mammal, it displays surprising powers of regeneration because it does not fibrose (i.e. scar) in response to tissue injury as most other mammals, including humans, do. In this Primer article, we review these regenerative abilities, highlighting the phylogenetic position of the spiny mouse relative to other rodents. We also briefly describe the Acomys tissues that have been used for regeneration studies and the common features of their regeneration compared with the typical mammalian response. Finally, we discuss the contribution that Acomys has made in understanding the general principles of regeneration and elaborate hypotheses as to why this mammal is successful at regenerating.

Protective properties of heme oxygenase-1 expressed in umbilical cord mesenchymal stem cells help restore the ovarian function of premature ovarian failure mice through activating the JNK/Bcl-2 signal pathway-regulated autophagy and upregulating the circulating of CD8+CD28- T cells

Background

Umbilical cord-derived mesenchymal stem cell (UCMSCs) transplantation has been widely studied in premature ovarian failure (POF). However, the underlying mechanism remains elusive. This study aims to investigate the protective properties and mechanisms of heme oxygenase-1 (HO-1) expressed in UCMSCs in restoring the ovarian function of POF mice.

Methods

In in vitro and in vivo experiments, mice were treated with the presence or absence of the HO-1/shHO-1-transfected UCMSCs, and the administration of SP600125 or anisomycin, the inhibitor or activator of JNK. The viability and apoptosis of granulosa cells (GCs) at different time points of co-cultivation were assessed in vitro. In in vivo experiments, mouse ovarian function was assessed by detecting the serum levels of hormone and observing the ovarian morphological changes. Multiple molecular indices of JNK/Bcl-2 signal pathway were performed. And the autophagy changes in GCs were assessed by detecting the associated cytokines and observing the intracellular autophagosome accumulation. Additionally, the spleen levels of CD8⁺CD28⁻ T cells and serum levels of interleukin 10 (IL-10) were tested to evaluate the immune mechanisms involved.

Results

UCMSCs transfected with shHO-1 or treated with SP600125 inhibited GCs’ viability and promoted its apoptosis in a time-dependent manner in vitro. In in vivo experiments, mice in both groups showed little therapeutic efficiency which presented as the increased extent of ovarian fibrosis with decreased number of functional follicles, and disordered hormone production. Additionally, the JNK/Bcl-2-associated cytokines were obviously declined. The inhibited autophagy-related cytokines, the chromatin condensation and abound vacuolar autophagosome in GCs, and weakened fluorescence intensity by MDC were observed. The downregulated levels of CD8⁺CD28⁻ T cells and serum levels of IL-10 were also detected. The damages above can be alleviated with HO-1-MSCs treatment or anisomycin administration.

Conclusions

HO-1 expressed in UCMSCs is critical in restoring the ovarian function in POF mice with UCMSC transplantation, which is mediated by the activation of JNK/Bcl-2 signal pathway-regulated autophagy and upregulating the circulating of CD8⁺CD28⁻ T cells.

Autophagy and Apoptosis of Porcine Ovarian Granulosa Cells During Follicular Development

Simple Summary

Granulosa cells (GCs) provide nutrients and information for oocytes in porcine follicles. Follicular atresia is closely related to both apoptosis and autophagy of granulosa cells in ovarian follicles; however, the follicular stages of granulosa cell apoptosis or autophagy during follicular development or atresia are poorly understood. We found that autophagy and apoptosis of GCs occurred in GCs from different size follicles during follicular development, and autophagy was mainly found in GCs of medium follicles, while apoptosis was mainly found in GCs of large follicles. These data provided some useful information to understand follicular atresia which is related to the fertility of sows.

Abstract

Follicular atresia is closely related to both apoptosis and autophagy of granulosa cells (GCs) in ovarian follicles. In the present study, GCs were isolated from pig ovaries in small, medium and large antral follicles, and the current results showed that the proliferation of GCs was higher in medium follicles, and lower in large follicles compared to small follicles. The Bax and Caspase 3 mRNA levels were significantly higher, but the ratio of Bcl-2/Bax was lower in GCs of large follicles. The marker genes of autophagy, Atg3, Atg7 and LC3 mRNA levels were higher in GCs from medium follicles. Apoptosis- and autophagy-related proteins had a similar expression pattern to the mRNA level. Our results showed that phosphorylated ERK (p-ERK) was activated in GCs of large follicles, while phosphorylated AKT (p-AKT) and phosphorylated mTOR (p-mTOR) were inhibited in GCs of medium follicles. Labeling of autophagic vesicles with 4’,6-diamidino-2-phenylindole (DAPI) and monodansylcadaverine (MDC) confirmed the results of gene transcription and protein expression in GCs of different size follicles. We conclude that autophagy and apoptosis of GCs occurred in different size follicles during follicular development, and autophagy was mainly found in GCs of medium follicles, while apoptosis was mainly found in GCs of large follicles.

Preantral follicular atresia occurs mainly through autophagy, while antral follicles degenerate mostly through apoptosis

There is a general agreement that granulosa cell apoptosis is the cause of antral follicle attrition. Less clear is whether this pathway is also activated in case of preantral follicle degeneration, as several reports mention that the incidence of granulosa cell apoptosis in preantral follicles is negligible. Our objective is therefore to determine which cell-death pathways are involved in preantral and antral follicular degeneration.Atretic preantal and antral follicles were investigated using immunohistochemistry and laser-capture microdissection followed by quantitative real-time reverse transcription polymerase chain reaction. Microtubule-associated light-chain protein 3 (LC3), sequestosome 1 (SQSTM1/P62), Beclin1, autophagy-related protein 7 (ATG7), and cleaved caspase 3 (cCASP3) were used as markers for autophagy and apoptosis, respectively. P62 immunostaining was far less intense in granulosa cells of atretic compared to healthy preantral follicles, while no difference in LC3 and BECLIN1 immunostaining intensity was observed. This difference in P62 immunostaining was not observed in atretic antral follicles. mRNA levels of LC3 and P62 were not different between healthy and atretic (pre)antral follicles. ATG7 immunostaining was observed in granulosa cells of preantral atretic follicles, not in granulosa cells of degenerating antral follicles. The number of cCASP3-positive cells was negligible in preantral atretic follicles, while numerous in atretic antral follicles. Taken together, we conclude that preantral and antral follicular atresia is the result of activation of different cell-death pathways as antral follicular degeneration is initiated by massive granulosa cell apoptosis, while preantral follicular atresia occurs mainly via enhanced granulosa cell autophagy.

ATG7 and ATG9A loss-of-function variants trigger autophagy impairment and ovarian failure

PURPOSE

Primary ovarian insufficiency (POI) is a frequent disorder that affects ~1% of women under 40 years of age. POI, which is characterized by the premature depletion of ovarian follicles and elevated plasma levels of follicle-stimulating hormone (FSH), leads to infertility. Although various etiological factors have been described, including chromosomal abnormalities and gene variants, most cases remain idiopathic. The aim of the present study was to identify and validate functionally new sequence variants in ATG (autophagy-related genes) leading to POI.

METHODS

We have reanalyzed, in silico, the exome sequencing data from a previously reported work performed in 69 unrelated POI women. Functional experiments using a classical hallmark of autophagy, the microtubule-associated protein 1 light chain 3β (LC3), were then used to link these genes to this lysosomal degradation pathway.

RESULTS

We venture a functional link between ATG7 and ATG9A variants and POI. We demonstrated that variant ATG7 and ATG9A led to a decrease in autophagosome biosynthesis and consequently to an impairment of autophagy, a key biological process implicated in the preservation of the primordial follicles forming the ovarian reserve.

CONCLUSION

Our results unveil that impaired autophagy is a novel pathophysiological mechanism involved in human POI.

PKCδ contributes to oxidative stress-induced apoptosis in porcine ovarian granulosa cells via activating JNK

Oxidative stress-induced apoptosis of granulosa cells (GCs) is believed to be an important cause of follicular atresia. Our previous work showed that the c-Jun N-terminal kinase (also known as JNK) might promote apoptosis in GCs during oxidative stress. The aim of this study was to investigate the upstream signaling required for JNK-mediated GCs apoptosis during oxidative stress. Since PKCδ and ASK1 have been suggested to regulate JNK activity in some types of cells, we hypothesized that PKCδ and ASK1 might contribute to JNK-dependent apoptosis in GCs suffering oxidative stimulation. To test this assumption, porcine GCs obtained from healthy follicles were treated with H₂O₂ alone, or together with inhibitors against PKCδ and JNK, and then collected for cell viability assay, TUNEL staining, immunoprecipitation, western blotting, or JNK activity detection in vitro. The current results showed that the cell viability loss, DNA fragmentation, morphological shrinkage, and nuclear condensation in H₂O₂-treated porcine GCs was correlated with enhanced activation of JNK. Although ASK1 was supposed to be a JNK activator, we found no definite role of ASK1 in JNK-induced GCs apoptosis during oxidative stress. Further investigations revealed that H₂O₂-mediated PKCδ activation was required for the apoptotic death of porcine GCs. Particularly, the pro-apoptotic effects of PKCδ on porcine GCs might be achieved by activating the mitochondrial pathway. Importantly, we found that p-PKCδ acts as an upstream activator of JNK in H₂O₂-treated porcine GCs. However, JNK has no regulatory effect on PKCδ activity. Taken together, our findings provided a novel model of GCs apoptosis involving the activation of PKCδ/JNK/mitochondrial apoptosis axis during oxidative stress.

Autophagy in Ovarian Follicular Development and Atresia

Autophagy is a mechanism that exists in all eukaryotes under a variety of physiological and pathological conditions. In the mammalian ovaries, less than 1% of follicles ovulate, whereas the remaining 99% undergo follicular atresia. Autophagy and apoptosis have been previously found to be involved in the regulation of both primordial follicular development as well as atresia. The relationship between autophagy, follicular development, and atresia have been summarized in this review with the aim to obtain a more comprehensive understanding of the role played by autophagy in follicular development and atresia.

Melatonin protects mouse granulosa cells against oxidative damage by inhibiting FOXO1-mediated autophagy: Implication of an antioxidation-independent mechanism

Oxidative stress has been described as a prime driver of granulosa cell (GCs) death during follicular atresia. Increasing evidence suggests potential roles of melatonin in protecting GCs from oxidative injury, though the underlying mechanisms remain largely undetermined. Here we first proposed that the inhibition of autophagy through some novel regulators contributes to melatonin-mediated GCs survival under conditions of oxidative stress. Oxidant-induced loss of GCs viability was significantly reduced after melatonin administration, which was correlated with attenuated autophagic signals upon oxidative stimulation both in vivo and in vitro. Compared with melatonin treatment, suppression of autophagy displayed similar preventive effect on GCs death during oxidative stress, but melatonin provided no additional protection in GCs pretreated with autophagy inhibitors. Notably, we found that melatonin-directed regulation of autophagic death was independent of its antioxidation/radical scavenging ability. Further investigations identified FOXO1 as a critical downstream effector of melatonin in promoting GCs survival from oxidative stress-induced autophagy. Specifically, suppression of FOXO1 via the melatonin-phosphatidylinositol 3-kinase (PI3K)-AKT axis not only improved GCs resistance to oxidative stress, but also abolished the autophagic response, from genes expression to the formation of autophagic vacuoles. Moreover, the activation of SIRT1 signaling was required for melatonin-mediated deacetylation of FOXO1 and its interaction with ATG proteins, as well as the inhibition of autophagic death in GCs suffering oxidative stress. These findings reveal a brand new mechanism of melatonin in defense against oxidative damage to GCs by repressing FOXO1, which may be a potential therapeutic target for anovulatory disorders.

•

Melatonin inhibits oxidative damage in GC without scavenging oxidative stress itself.

•

Melatonin protects GC from oxidative damage via inhibiting autophagic cell death.

•

Inhibition of FOXO1-dependent autophagy by melatonin reduces oxidative damage in GC.

•

Suppression of autophagy through melatonin-PI3K-AKT-FOXO1 axis improves GC survival.

•

Melatonin reduces oxidative injury by inhibiting SIRT1-FOXO1-ATG7-dependent autophagy.

Germ cell depletion from mammalian ovary: possible involvement of apoptosis and autophagy

Mammalian ovary contains millions of germ cells during embryonic life but only few of them are culminated into oocytes that achieve meiotic competency just prior to ovulation. The majority of germ cells are depleted from ovary through several pathways. Follicular atresia is one of the major events that eliminate germ cells from ovary by engaging apoptotic as well as non-apoptotic pathways of programmed cell death. Apoptosis is characterized by several morphological changes that include cell shrinkage, nuclear condensation, membrane blebbing and cytoplasmic fragmentation by both mitochondria- as well as death receptor-mediated pathways in encircling granulosa cells and oocyte. Although necroapoptosis have been implicated in germ cell depletion, autophagy seems to play an active role in the life and death decisions of ovarian follicles. Autophagy is morphologically characterized by intracellular reorganization of membranes and increased number of autophagic vesicles that engulf bulk cytoplasm as well as organelles. Autophagy begins with the encapsulation of cytoplasmic constituents in a membrane sac known as autophagosomes. The autophagic vesicles are then destroyed by the lysosomal enzymes such as hydrolases that results in follicular atresia. It seems that apoptosis as well as autophagy could play active roles in germ cells depletion from ovary. Hence, it is important to prevent these two pathways in order to retain the germ cells in ovary of several mammalian species that are either threatened or at the verge of extinction. The involvement of apoptosis and autophagy in germ cell depletion from mammalian ovary is reviewed and possible pathways have been proposed.

Non-suckling starvation of neonatal mice promotes primordial follicle formation with activation of ovarian autophagy

Around the time of oocyte meiotic arrest, germ cell nest breakdown occurs, and primordial follicle (PF) formation is initiated at the perinatal stage. Recently, autophagy was implicated in this process. Autophagy is induced by nutrient starvation. This study was conducted to understand how starvation affects PF formation and autophagy induction during neonatal life. Suckling of neonatal female mice was blocked immediately after birth for 12–36 h to induce starvation. The numbers of PFs at each stage were subsequently counted from serial sections of ovaries. The expression of autophagy-related proteins was also evaluated. The number of PFs peaked at 60 h after birth in the control group. The numbers for the starvation groups were significantly higher than those for the control groups at 12 and 36 h. LC3B was clearly present in the oocyte cytoplasm. At 36 h after birth, the starvation group showed a higher rate of LC3II/LC3-I expression as a marker for autophagy. Moreover, the expression of p62 as a selective substrate for autophagy decreased compared to the control group. The expression of caspase-9 as a marker for apoptosis tended to be lower at 36 h in the starvation groups. These results indicate that starvation promotes PF formation with a concomitant activation of autophagy in early neonatal ovaries, suggesting that autophagy induction during follicle assembly might increase the number of PFs.

Administration of follicle-stimulating hormone induces autophagy via upregulation of HIF-1α in mouse granulosa cells

Recent studies reported the important role of autophagy in follicular development. However, the underlying molecular mechanisms remain elusive. In this study, we investigated the effect of follicle-stimulating hormone (FSH) on mouse granulosa cells (MGCs). Results indicated that autophagy was induced by FSH, which is known to be the dominant hormone regulating follicular development and granulosa cell (GC) proliferation. The activation of mammalian target of rapamycin (mTOR), a master regulator of autophagy, was inhibited during the process of MGC autophagy. Moreover, MHY1485 (an agonist of mTOR) significantly suppressed autophagy signaling by activating mTOR. The expression of hypoxia-inducible factor 1-alpha (HIF-1α) was increased after FSH treatment. Blocking hypoxia-inducible factor 1-alpha attenuated autophagy signaling. In vitro, CoCl₂-induced hypoxia enhanced cell autophagy and affected the expression of beclin1 and BCL2/adenovirus E1B interacting protein 3 (Bnip3) in the presence of FSH. Knockdown of beclin1 and Bnip3 suppressed autophagy signaling in MGCs. Furthermore, our in vivo study demonstrated that the FSH-induced increase in weight was significantly reduced after effectively inhibiting autophagy with chloroquine, which was correlated with incomplete mitophagy process through the PINK1-Parkin pathway, delayed cell cycle, and reduced cell proliferation rate. In addition, chloroquine treatment decreased inhibin alpha subunit, but enhanced the expression of 3 beta-hydroxysteroid dehydrogenase. Blocking autophagy resulted in a significantly lower percentage of antral and preovulatory follicles after FSH stimulation. In conclusion, our results indicate that FSH induces autophagy signaling in MGCs via HIF-1α. In addition, our results provide evidence that autophagy induced by FSH is related to follicle development and atresia.

Mechanisms controlling germline cyst breakdown and primordial follicle formation

In fetal females, oogonia proliferate immediately after sex determination. The progress of mitosis in oogonia proceeds so rapidly that the incompletely divided cytoplasm of the sister cells forms cysts. The oogonia will then initiate meiosis and arrest at the diplotene stage of meiosis I, becoming oocytes. Within each germline cyst, oocytes with Balbiani bodies will survive after cyst breakdown (CBD). After CBD, each oocyte is enclosed by pre-granulosa cells to form a primordial follicle (PF). Notably, the PF pool formed perinatally will be the sole lifelong oocyte source of a female. Thus, elucidating the mechanisms of CBD and PF formation is not only meaningful for solving mysteries related to ovarian development but also contributes to the preservation of reproduction. However, the mechanisms that regulate these phenomena are largely unknown. This review summarizes the progress of cellular and molecular research on these processes in mice and humans.

The role of germ cell loss during primordial follicle assembly: a review of current advances

In most female mammals, early germline development begins with the appearance of primordial germ cells (PGCs), and develops to form mature oocytes following several vital processes. It remains well accepted that significant germ cell apoptosis and oocyte loss takes place around the time of birth. The transition of the ovarian environment from fetal to neonatal, coincides with the loss of germ cells and the timing of follicle formation. All told it is common to lose approximately two thirds of germ cells during this transition period. The current consensus is that germ cell loss can be attributed, at least in part, to programmed cell death (PCD). Recently, autophagy has been implicated as playing a part in germ cell loss during the time of parturition. In this review, we discuss the major opinions and mechanisms of mammalian ovarian PCD during the process of germ cell loss. We also pay close attention to the function of autophagy in germ cell loss, and speculate that autophagy may also serve as a critical and necessary process during the establishment of primordial follicle pool.

FSH protects mouse granulosa cells from oxidative damage by repressing mitophagy

Oxidative stress has been implicated in triggering granulosa cell (GC) death during follicular atresia. Recent studies suggested that follicle-stimulating hormone (FSH) has a pivotal role in protecting GCs from oxidative injury, although the exact mechanism remains largely unknown. Here, we report that FSH promotes GC survival by inhibiting oxidative stress-induced mitophagy. The loss of GC viability caused by oxidative stress was significantly reduced after FSH treatment, which was correlated with impaired activation of mitophagy upon oxidative stress. Compared with FSH treatment, blocking mitophagy displayed approximate preventive effect on oxidative stress-induced GC death, but FSH did not further restore viability of cells pretreated with mitophagy inhibitor. Importantly, FSH suppressed the induction of serine/threonine kinase PINK1 during oxidative stress. This inhibited the mitochondrial translocation of the E3 ligase Parkin, which is required for the subsequent clearance of mitochondria, and ultimately cell death via mitophagy. In addition, knocking down PINK1 using RNAi confirmed the role of the FSH-PINK1-Parkin-mitophagy pathway in regulating GC survival under oxidative conditions. These findings introduce a novel physiological function of FSH in protecting GCs against oxidative damage by targeting PINK1-Parkin-mediated mitophagy.

Paraptosis-like cell death in Wistar rat granulosa cells

Follicular atresia, a common process present in all mammals, involves apoptotic and autophagic cell death. However, the participation of paraptosis, a type of caspase-independent cell death, during follicular atresia is unknown. This study found swollen endoplasmic reticulum in the granulosa cells of adult Wistar rats. Calnexin was used as a marker of the endoplasmic reticulum at the ultrastructural and optical levels. The cells with swelling of the endoplasmic reticulum were negative to the TUNEL assay and active caspase-3 immunodetection, indicating that this swelling is not part of any apoptotic or autophagic process. Additionally, immunodetection of the CHOP protein was used as a marker of endoplasmic reticulum stress, and this confirmed the presence of the paraptosis process. These data suggest that paraptosis-like cell death is associated with the death of granulosa cells during follicular atresia in adult Wistar rats.

Prenatally administered dexamethasone impairs folliculogenesis in spiny mouse offspring

This study was designed to determine whether prenatal dexamethasone treatment has an effect on follicular development and atresia in the ovary of spiny mouse (Acomys cahirinus) offspring. Dexamethasone (125µg kg-1 bodyweight per day) was administered to pregnant spiny mice from Day 20 of gestation to parturition. The processes of follicle loss were analysed using classical markers of apoptosis (terminal deoxynucleotidyl transferase-mediated dUTP nick end-labelling reaction, active caspase-3) and autophagy (Lamp1). The present study indicated that dexamethasone reduced the pool of healthy primordial follicles. Moreover, the oocytes from these follicles showed intensive caspase-3 and Lamp1 staining. Surprisingly, dexamethasone caused an increase in the number of secondary follicles; however, most of these follicles were characterised by extensive degeneration of the oocyte and caspase-3 and Lamp1 labelling. Western-blot analysis indicated that the glucocorticoid receptor as well as apoptosis and autophagy markers were more strongly expressed in the DEX-treated group than in the control. On the basis of these findings, we have concluded that dexamethasone impairs spiny mouse folliculogenesis and enhances follicular atresia through induction of autophagy or combined autophagy and apoptosis.

Follicle-stimulating hormone-induced rescue of cumulus cell apoptosis and enhanced development ability of buffalo oocytes

The effect of follicle-stimulating hormone (FSH) on apoptotic status of cumulus cells, expression of proapoptotic and antiapoptotic genes, and development rate of in vitro fertilization-produced buffalo embryos were investigated. FSH supplementation in in vitro maturation-medium resulted in a dose-dependent reduction in the expression of proapoptotic genes namely, BCL2-associated X protein (BAX), cytochrome c, and caspase-3 and increase in the expression of antiapoptotic genes such as B-cell lymphoma 2 (BCL2) and X-linked inhibitor of apoptosis protein (XIAP) in cumulus cells of mature oocyte. Cumulus expansion, oocyte maturation, cleavage, and blastocyst development rates were significantly higher (P < 0.05) in 5 and 10-μg/mL FSH-supplemented groups as compared with control. Significant increase in the expression of FSH receptor messenger RNA was also found with 5 and 10-μg/mL FSH (P < 0.05). Terminal deoxynucleotidyl transferase dUTP nick end labeling assay confirmed that the population of apoptotic cumulus cells of matured oocytes was reduced in the FSH-treated groups as compared with control (P < 0.05). In conclusion, our data suggest that FSH may attenuate apoptosis in cumulus cells via mitochondria-dependent apoptotic pathway by increasing XIAP expression, resulting in a more favorable ratio of BCL2/BAX expression and decreasing the cytochrome c and caspase-3 expression, eventually contributing to developmental competence of oocytes. The information generated will help in improving the in vitro embryo production program in buffalo.

New Insights into the Role of Autophagy in Ovarian Cryopreservation by Vitrification

Ovarian cryopreservation by vitrification is a highly useful method for preserving female fertility during radiotherapy and chemotherapy. However, cryoinjury, osmotic stress during vitrification, and ischemia/reperfusion during transplantation lead to loss of ovarian follicles. Ovarian follicle loss may be partially reduced by several methods; however, studies regarding the mechanism of ovarian follicle loss have only investigated cell apoptosis, which consists of type I programmed cell death. Autophagy is type II programmed cell death, and cell homeostasis is maintained by autophagy during conditions of stress. The role of autophagy during cryopreservation by vitrification has rarely been reported. The potential role of autophagy during ovarian cryopreservation by vitrification is reviewed in this article.

Germ cell-specific Atg7 knockout results in primary ovarian insufficiency in female mice

Primary ovarian insufficiency (POI) is a common cause of infertility in around 1–2% of women aged <40 years. However, the mechanisms that cause POI are still poorly understood. Here we showed that germ cell-specific knockout of an essential autophagy induction gene Atg7 led to subfertility in female mice. The subfertility of Atg7 deletion females was caused by severe ovarian follicle loss, which is very similar to human POI patients. Further investigation revealed that germ cell-specific Atg7 knockout resulted in germ cell over-loss at the neonatal transition period. In addition, our in vitro studies also demonstrated that autophagy could protect oocytes from over-loss by apoptosis in neonatal ovaries under the starvation condition. Taken together, our results uncover a new role for autophagy in the regulation of ovarian primordial follicle reservation and hint that autophagy-related genes might be potential pathogenic genes to POI of women.

Tumor necrosis factor alpha inhibits ovulation and induces granulosa cell death in rat ovaries

Purpose

We evaluated the role of tumor necrosis factor alpha (TNFα) in rat ovulation and granulosa cell death of ovarian follicles during the periovulatory stage.

Methods

Immature rats primed with pregnant mare serum gonadotropin were injected intraperitoneally with human chorionic gonadotropin (hCG), and TNFα was injected into the bursa 48 h later. The total number of released oocytes was counted. Apoptosis was measured with terminal deoxynucleotidyl transferase‐mediated dUTP nick end labeling (TUNEL) and the expression of cleaved caspase 3 and Bax/Bcl‐2. Autophagy was assessed by the expression of light chain protein 3 (LC3) and autophagosomes under transmission electron microscopy.

Results

TNFα significantly decreased the number of released oocytes, and many unruptured follicles were observed. TUNEL analysis revealed a larger number of apoptotic cells, and the cleaved caspase 3 and Bax/Bcl‐2 increased more than that of the control 12 h after hCG administration. Furthermore, the expression of LC3 wwas significantly higher than that of the control, and autophagosomes were observed in the cytoplasm.

Conclusions

Our data indicated that TNFα is an important mediator of ovulation in terms of decreasing the number of released oocytes and inducing granulosa cell death of unruptured follicles via apoptosis and autophagy for remodeling ovarian tissues.

The effect of calorie restriction on the presence of apoptotic ovarian cells in normal wild type mice and low-plasma-IGF-1 Laron dwarf mice

Background

It is known that caloric restriction extends lifespan and can minimize age-related dysfunction of the reproductive system. We became interested in how caloric restriction influences apoptosis, which is a crucial process that maintains ovarian cell homeostasis.

Methods

We examined ovarian cells in: 2.5-year-old wild type mice on caloric restriction (CR) or fed ad libitum (AL) and Laron dwarf mice (GHR-KO) at the same ages on CR or fed AL. Apoptosis was assessed by histochemical analysis on paraffin sections of ovarian tissue.

Results

Morphological and histochemical analysis revealed that CR improved reproductive potential in 2.5-year-old WT littermates and GHR-KO female mice, as indicated by the increased number of ovarian follicles. The level of apoptosis in ovarian tissue was higher in WT mice on a CR diet compared with WT mice on the AL diet. In GHR-KO mice, the level of apoptosis in ovaries was similar for mice on CR and on AL diets and bigger than in WT mice on CR.

Conclusions

Morphological and histochemical analysis revealed a younger biological age of the ovaries in 2-year-old WT littermates and GHR-KO female mice on CR compared with animals fed AL.

Apoptosis of human ovarian tissue is not increased by either vitrification or rapid cooling

This study evaluated the incidence of morphological changes, as assessed by light microscopy, and apoptosis in vitrified and rapidly cooled human ovarian tissue. Apoptosis was assessed 30 min and 24h after warming using transmission electron microscopy, terminal deoxynucleotidyl transferase-mediated dUDP nick-end labelling (TUNEL) assay and DNA fragmentation, as determined by gel electrophoresis. The results showed no significant changes in morphology, chromatin condensation, DNA fragmentation or TUNEL-positive cells in follicles attributable to cryopreservation or exposure to the cryoprotectant solutions alone. In conclusion, the cryopreservation protocols did not affect the incidence of apoptosis and either protocol could be an alternative to slow cooling of ovarian tissue. This study evaluated the incidence of morphological changes, as assessed by light microscopy, and apoptosis in human ovarian tissue cryopreserved using two different methods, i.e. vitrification and rapid cooling. Apoptosis was assessed in tissue 30 min and 24h after warming using transmission electron microscopy and terminal deoxynucleotidyl transferase-mediated dUDP nick-end labelling (TUNEL) assay and DNA fragmentation as determined by gel electrophoresis. The results showed no significant changes in morphology, chromatin condensation, DNA fragmentation or TUNEL-positive cells in follicles attributable to cryopreservation or exposure to the cryopreservation solutions alone. In conclusion, the cryopreservation protocols did not affect the incidence of apoptosis in human ovarian tissue and either protocol could be an alternative to slow cooling for the preservation of ovarian tissue.