Search Results (102)

This review aims to discuss how heat stress affects ovarian follicles and oocytes, steroidogenesis, and embryo development in ruminants. The literature shows that quiescent primordial follicles appear to be less susceptible to heat stress, but from the primary follicle stage onwards, they begin to suffer the consequences of heat stress. These adverse effects are exacerbated when the follicles are cultured in vitro. In antral follicles, heat stress reduces granulosa cell viability and proliferation in both in vivo and in vitro models. Oocyte maturation, both nuclear and cytoplasmic, is also compromised, and embryo quality declines under elevated thermal conditions. These effects are linked to intracellular disturbances, including oxidative imbalance, mitochondrial dysfunction, and altered hormonal signaling. The differences between in vivo and in vitro responses reflect the complexity of the biological impact of heat stress and emphasize the protective role of the physiological microenvironment. A better understanding of how heat stress alters the function of ovarian follicles, oocytes, and embryos is crucial. This knowledge is critical to devise effective strategies that mitigate damage, support fertility, and improve outcomes in assisted reproduction for livestock exposed to high environmental temperatures. Full article

Polygoni Multiflori Radix Praeparata (PMRP), a processed root of Polygonum multiflorum Thunb. (known as Zhiheshouwu in Chinese medicine), exhibits anti-aging properties and is used to improve ovarian aging. However, its therapeutic mechanism against premature ovarian insufficiency (POI) remains unclear. This study investigates whether PMRP alleviates POI by inhibiting PANoptosis—a cell death pathway characterized by the concurrent occurrence and interplay of pyroptosis, apoptosis, and necroptosis. POI was induced in rats using tripterygium glycosides. We evaluated the estrous cycle, serum hormone levels (follicle-stimulating hormone [FSH], estrogen [E₂], anti-Müllerian hormone [AMH]), follicular development, and the ultrastructure of granulosa cells. PANoptosome assembly (apoptosis-associated speck-like protein containing a CARD [ASC]/caspase-8/receptor-interacting protein kinase 3 [RIPK3] co-localization) and key effectors of PANoptosis (caspase 3, cleaved caspase 3, gasdermin D [GSDMD], cleaved GSDMD, GSDME, RIPK1, mixed-lineage kinase domain-like protein [MLKL], and p-MLKL) were analyzed. PMRP restored the estrous cycle, lowered FSH levels, and increased E₂ and AMH levels in POI rats. It reduced follicular atresia, preserved primordial follicles, and suppressed PANoptosis-like death in granulosa cells. Mechanistically, PMRP disrupted PANoptosome assembly and downregulated key effectors of PANoptosis. PMRP alleviates POI by inhibiting PANoptosis in granulosa cells, overcoming the previous limitations of targeting single death pathways and providing novel insights into the pathogenesis and treatment strategies for POI. Full article

Climate change poses an increasing threat to livestock reproduction, with heat stress (HS) known to significantly impair ovarian function. This study aimed to elucidate the impact of HS on ovarian function and circRNA expression profiles in Hu sheep. Twelve ewes were randomly assigned to a control (Con, n = 6) or HS group (n = 6) and exposed to different temperatures for 68 days. Compared with the Con group, HS significantly increased the respiratory rate (108.33 ± 3.72 vs. 63.58 ± 2.42 breaths/min), pulse rate (121.17 ± 3.98 vs. 78.08 ± 3.31 beats/min), and rectal temperature (40.17 ± 0.14 °C vs. 39.02 ± 0.21 °C; p < 0.05). Concurrently, serum antioxidant levels were markedly decreased, including total antioxidant capacity (T-AOC), total superoxide dismutase (T-SOD), and glutathione peroxidase (GSH-Px) (p < 0.05). Histological analysis revealed a significant reduction in the numbers of primordial, primary, secondary, and mature follicles, alongside an increase in antral follicles (p < 0.05). TUNEL staining demonstrated enhanced granulosa cell apoptosis (p < 0.05), accompanied by the upregulation of pro-apoptotic genes Bax and Caspase-3 and downregulation of the anti-apoptotic gene Bcl-2, as confirmed by qPCR (p < 0.05). CircRNA sequencing identified 152 differentially expressed circRNAs (120 upregulated, 32 downregulated), and enrichment analyses indicated their involvement in apoptosis, mitophagy, and the FoxO signaling pathway. Collectively, these findings demonstrate that HS impairs ovarian physiology and antioxidant defense, induces follicular damage and cell apoptosis, and alters circRNA expression profiles, providing new insights into the molecular mechanisms underlying HS-induced reproductive dysfunction in Hu sheep. Full article

Urolithin A, which is a natural gut microbial metabolite, exerts multiple beneficial effects upon supplementation, including prolonging lifespan, mitigating diseases, restoring the quality of aged oocytes and alleviating drug toxicity. The study aims to investigate the ovarian protective role of Urolithin A using a neonatal mouse ovarian in vitro culture and chemotherapy model, with a particular focus on its mechanisms for inhibiting primordial follicle activation and mitigating cyclophosphamide (CY) or 4-hydroperoxy (4-HC)-induced follicle apoptosis. The results showed that Urolithin A significantly decreased the number of growing follicles and downregulated the expression of oocyte growth-related genes (Gdf9 and Zp3) and protein (DDX4), as well as Ki-67 and BrdU-positive signals. Further studies revealed that Urolithin A significantly downregulated the levels of phosphorylated Akt and FOXO3a and decreased the percentage of oocytes with FOXO3a nuclear export. Molecular docking showed a strong binding ability between Urolithin A and its downregulated gene Pik3cg. Moreover, Urolithin A significantly decreased CY- and 4-HC-induced increases in cleaved Caspase-3- and PARP1-positive signals. Meanwhile, RNA-seq analysis indicated that Urolithin A significantly downregulated CY-induced expression of DNA damage-related genes (Trp73 and Trim29). In short, Urolithin A inhibits primordial follicle activation by reducing PI3K/Akt signaling reactivity. Furthermore, Urolithin A prevents CY-induced follicle apoptosis. The study provides valuable insights into Urolithin A treatment for chemotherapy-induced infertility. Full article

Proteases play crucial roles in ovarian folliculogenesis, regulating several processes from primordial follicle activation to ovulation and corpus luteum formation. This review synthesizes the current knowledge on the diverse functions of proteases in ovarian physiology and pathology. We discuss the classification and regulation of proteases, highlighting their importance in extracellular matrix remodeling, cell signaling, and apoptosis during ovarian follicular development. We explore the roles of several proteases including matrix metalloproteinases, tissue inhibitors of metalloproteinases, the plasminogen activator system, and cathepsins, and their roles in the critical functions of ovarian biology including follicle dynamics and senescence. Furthermore, we address the involvement of proteases in ovarian pathologies, including cancer, polycystic ovary syndrome, and primary ovarian insufficiency. By integrating recent findings from clinical genomics and animal models, this review provides a comprehensive overview of protease functions in the ovary, emphasizing their potential use for therapeutic interventions in reproductive medicine. Full article

Ion channels play a crucial role in various physiological processes, yet their functions in the reproductive system remain underexplored. This study investigates the expression and the localization of ASIC2, ASIC4, and PIEZO2 ion channels in the reproductive tracts of prepubertal bitches. Western blotting on samples from eight prepubertal bitches confirmed the presence of these ion channels in ovarian, uterine, and uterine tubes tissues, and validated antibody specificity. Immunohistochemistry revealed that all primordial follicles expressed these ion channels, while only some developing follicles showed immunolabeling. These findings suggest ion channels’ potential involvement in oocyte differentiation and maturation. The localization of these channels in uterine tubes, uterine lining, and glandular epithelium suggests a role in tissue maintenance, oocyte transport, and embryo implantation. Additionally, their expression in the tunica media of reproductive vasculature points to a potential role in vascular regulation. Future studies are needed to elucidate the specific mechanisms underlying the role of these channels in reproductive physiology. Full article

The aim of this study is to examine the influence of food restriction on rabbit ovarian functions. A total of eight females were fed ad libitum (NF), while eight females were subjected to 50% food restriction (RF). One month later, all females were euthanized. Weights and lengths of ovaries and uterine horns were measured. Representative parts of the ovaries were subjected to histomorphometry analysis of folliculogenesis. Granulosa cells were isolated and cell viability, proliferation (accumulation of PCNA, cyclin B1, and BrdU-positive cells), apoptosis (accumulation of bax, caspase 3, and DNA fragmentation) were evaluated. Granulosa cells were subjected to proteomic analysis by using the nano HPLC-Chip-MS/MS method. Estradiol and progesterone release by ovarian and granulosa cells was assessed by ELISA. Ovarian and uterine horn weights were lower in RF than NF. The diameter of follicles and oocytes and the thickness of the theca and granulosa cells were higher in RF than NF. RF showed a lower percentage of cells containing bax and caspase 3, occurrence of DNA fragmented cells, and estradiol and progesterone. RF had higher incorporation of BrdU, a higher proportion of cells containing PCNA and cyclin B1, and a lower percentage of viable cells. RF produced more specific proteins than NF, including peptides involved in cell differentiation, proliferation/division, mitotic cell cycle, and GTP-ase activity. In conclusion, food restriction can activate reproduction by (1) selection of the growing primordial follicles, (2) better transformation of secondary to preovulatory follicles, (3) increasing growth of oocytes, (4) increasing proliferation and decreasing apoptosis in granulosa cells, (5) changes in ovarian secretory activity, and (6) changes in the number of peptides. Full article

Follicle development is a critical process in mammalian reproduction, with significant implications for ovarian reserve and fertility. Stra8 is a known key factor regulating the initiation of meiosis; however, oocyte-like cells still appear in Stra8-deficient mice. Nevertheless, the underlying mechanism remains unclear and requires further investigation. Therefore, we used single-cell RNA sequencing to construct a comprehensive transcriptional atlas of ovarian cells from both wild-type and Stra8-deficient mice at embryonic stages E14.5 and E16.5. With stringent quality control, we obtained a total of 14,755 single cells of six major cell types. A further fine-scale analysis of the germ cell clusters revealed notable heterogeneity between wild-type and Stra8-deficient mice. Compared to the wild-type mice, the deficiency in Stra8 led to the downregulation of meiosis-related genes (e.g., Pigp, Tex12, and Sycp3), and the upregulation of apoptosis-related genes (e.g., Fos, Jun, and Actb), thereby hindering the meiotic process. Notably, we observed that, following Stra8 deficiency, the expression levels of Sub1 and Stk31 remained elevated at this stage. Furthermore, an RNA interference analysis confirmed the potential role of these genes as regulatory factors in the formation of primordial follicle-like cells. Additionally, Stra8 deficiency disrupted the signaling between germ cells and pregranulosa cells that is mediated by Mdk–Sdc1, leading to the abnormal expression of the PI3K/AKT signaling pathway. Together, these results shed light on the molecular processes governing germ cell differentiation and folliculogenesis, emphasizing the complex role of Stra8 in ovarian function. Full article

Ovarian endometriosis (OEM) is a chronic inflammatory condition that impairs ovarian function. While its effects on ovarian reserve are well established, the long-term consequences of OEM on ovarian dysfunction, premature ovarian failure (POF), and systemic health, particularly in the context of accelerated aging, remain insufficiently studied. In this study, we employed an OEM mouse model and bulk RNA sequencing to investigate the underlying mechanisms. Our results show that OEM accelerates primordial follicle depletion and upregulates mTOR signaling pathway gene expression, along with mechanical stress and paracrine signaling via the Hippo and Myc pathways. OEM also induces irregular estrus and ovarian fibrosis in aging mice, decreases serum AMH levels, and increases FSH levels. Systemically, elevated serum IgG levels contribute to osteoporosis and cognitive decline, both linked to ovarian dysfunction and POF in OEM. These findings elucidate the mechanisms driving premature ovarian reserve depletion in OEM and highlight its broader systemic effects. This study emphasizes the importance of monitoring ovarian health and ectopic tissue to safeguard ovarian reserves and mitigate long-term risks such as osteoporosis and cognitive decline. Full article

Objectives: This study aimed to elucidate the effects of messenger RNA (mRNA) and inactivated coronavirus disease 2019 (COVID-19) vaccines on ovarian histology and reserve in rats. Methods: Thirty female Wistar albino rats, aged 16–24 weeks, were randomly divided into three groups (n = 10): control, mRNA vaccine, and inactivated vaccine groups. Each vaccine group received two doses (on day 0 and day 28) at human-equivalent doses. Four weeks post-second vaccination, ovarian tissues were harvested for analysis. Results: Immunohistochemical analysis was performed to evaluate the expression of transforming growth factor beta-1 (TGF-β1), vascular endothelial growth factor (VEGF), caspase-3, and anti-Müllerian hormone (AMH) in ovarian follicles. Both vaccines induced significant increases in TGF-β1, VEGF, and caspase-3 expression, with more pronounced effects in the mRNA vaccine group. Conversely, AMH expression in the granulosa cells of primary, secondary, and antral follicles showed marked reductions (p < 0.001). The counts of primordial, primary, and secondary follicles decreased significantly in the inactivated vaccine group relative to controls and further in the mRNA vaccine group compared to the inactivated group (p < 0.001). Additionally, the mRNA vaccine group exhibited a decrease in antral and preovulatory follicles and an increase in atretic follicles compared to the other groups (p < 0.05). The serum AMH level was diminished with the mRNA vaccination in comparison with the control and inactivated groups. Conclusions: Our findings suggest that both mRNA and inactivated COVID-19 vaccines may detrimentally impact ovarian reserve in rats, primarily through accelerated follicular loss and alterations in apoptotic pathways during folliculogenesis. Given these observations in a rat model, further investigations into the vaccines’ effects on human ovarian reserve are needed. Full article

Prenatal stress (PNS) impairs offspring ovarian development by exerting negative long-term effects on postnatal ovarian function and folliculogenesis. FKBP51 is a stress-responsive protein that inhibits glucocorticoid and progesterone receptors. We hypothesize that FKBP51 contributes to impaired ovarian development and folliculogenesis induced by PNS. Timed-pregnant Fkbp5^+/+ (wild-type) and Fkbp5^−/− (knockout) mice were randomly assigned to either the undisturbed (nonstress) or PNS group, with exposure to maternal restraint stress from embryonic days 8 to 18. Ovaries from the offspring were harvested and stained, and follicles were counted according to their stages. Ovarian expressions of FKBP51 were evaluated by immunohistochemistry and Fkbp5 and steroidogenic enzymes were evaluated by qPCR. Compared to controls, Fkbp5^+/+ PNS offspring had increased peripubertal primordial follicle atresia and fewer total follicles in the adult and middle-aged groups. In adult Fkbp5^+/+ offspring, PNS elevated FKBP51 levels in granulosa cells of primary to tertiary follicles. Our results suggest that PNS administration increased FKBP51 levels, depleted the ovarian reserve, and dysregulated ovarian steroid synthesis. However, these PNS effects were tolerated in Fkbp5^−/− mice, supporting the conclusion that FKBP51 contributes to reduced ovarian reserve induced by PNS. Full article

In vitro embryo production has accelerated in the cattle industry in recent years. Because women are similar to cows, this represents an opportunity to improve women’s reproductive protocols. This review focuses on crosstalk communication during folliculogenesis for an in-depth understanding of the events involved in developing the oocyte competence necessary to generate an embryo after fertilization. This knowledge can be used to improve oocytes in in vitro maturation cultures, which would allow us to obtain oocytes of high quality and competence, resulting in successful pregnancies in both women and cows. The first part of this review covers the concepts of cellular crosstalk before puberty in the primordial, primary, and secondary follicles. The next part involves cellular crosstalk after puberty, when gonadotropin hormones act on the ovary, promoting oocyte maturation. The final part comprises a perspective on using cow models to study human ovary physiology. Full article

Background/Objectives: Endometriosis has a marked impact on fertility, although the mechanisms behind this relationship remain poorly understood, particularly in cases without significant anatomical distortions or in the context of ovarian endometriomas. This study aimed to investigate the effect of peritoneal endometriosis on ovarian function by assessing ovarian reserve and apoptosis. Methods: Peritoneal endometriosis was surgically induced in Sprague Dawley rats through the autotransplantation of uterine fragments onto the bowel mesothelium. One month post-surgery, ovarian structures were counted, follicle and corpora lutea apoptosis was evaluated by TUNEL, and apoptotic-related protein expression in ovaries was assessed by Western blot. Additionally, a co-culture system using 12Z endometriotic and KGN granulosa cell lines was utilized to evaluate gene expression by RT-qPCR. Results: Rats with peritoneal endometriosis exhibited a significant reduction in ovarian structures characterized by a low number of total follicles, particularly primordial, primary, preantral, and late-antral follicles. Consistently, AMH protein expression was decreased in ovaries in the presence of endometriosis. In addition, this disease led to a significant increase in late-antral follicles that were TUNEL-positive and in the number of apoptotic cells in corpora lutea, indicating higher apoptosis in endometriosis ovaries. Concomitantly, the altered expression of apoptosis-related proteins was observed, with increased procaspase 3 and decreased BCL-2 expression. In addition, KGN granulosa cells co-cultured with 12Z endometriotic cells displayed reduced KITLG mRNA expression and increased AMHR2 mRNA expression. Conclusions: Peritoneal endometriosis significantly impairs ovarian health by disrupting folliculogenesis, reducing ovarian reserve, and increasing apoptosis, potentially accelerating ovarian aging and contributing to infertility. These results underscore the need for further research to identify the molecular pathways involved and to develop targeted therapeutic strategies. Full article

We analyzed the transcriptome data of wildtype and estrogen receptor β knockout (Erβ^KO) rat ovaries during the early postnatal period and detected remarkable changes in epigenetic regulators and transcription factors. Compared with postnatal day (PD) 4.5 ovaries, PD 6.5 wildtype ovaries possessed 581 differentially expressed downstream transcripts (DEDTs), including 17 differentially expressed epigenetic regulators (DEERs) and 23 differentially expressed transcription factors (DETFs). Subsequently, compared with PD 6.5 ovaries, PD 8.5 wildtype ovaries showed 920 DEDTs, including 24 DEERs and 68 DETFs. The DEDTs, DEERs, and DETFs in wildtype ovaries represented the gene expression during primordial follicle activation and the gradual development of primary follicles of first-wave origin because the second-wave follicles remained dormant during this developmental period. When we compared the transcriptome data of age-matched Erβ^KO ovaries, we observed that PD 6.5 Erβ^KO ovaries had 744 DEDTs compared with PD 4.5 ovaries, including 46 DEERs and 55 DETFs. The loss of ERβ rapidly activated the primordial follicles of both first- and second-wave origin on PD 6.5 and showed a remarkable increase in DEDTs (744 vs. 581). However, compared with PD 6.5 ovaries, PD 8.5 Erβ^KO ovaries showed only 191 DEDTs, including 8 DEERs and 10 DETFs. This finding suggests that the PD 8.5 Erβ^KO ovaries did not undergo remarkable ovarian follicle activation greater than that had already occurred in PD 6.5 Erβ^KO ovaries. The results also showed that the numbers of DEERs and DETFs were associated with increased changes in DEDTs; the greater the number of DEERs or DETFs, the larger the number of DEDTs. In addition to the quantitative differences in DEERs and DETFs between the wildtype and Erβ^KO ovaries, the differentially expressed regulators showed distinct patterns. We identified that 17 transcripts were tied to follicle assembly, 6 to follicle activation, and 12 to steroidogenesis. Our observations indicate that a loss of ERβ dysregulates the epigenetic regulators and transcription factors in Erβ^KO ovaries, which disrupts the downstream genes in ovarian follicles and increases follicle activation. Further studies are required to clarify if ERβ directly or indirectly regulates DEDTs, including DEERs and DETFs, during the neonatal development of rat ovarian follicles. Full article

The objective of this study was to characterize and estimate the population of ovarian preantral follicles in juvenile six-banded armadillos. Pairs of ovaries from five armadillos were collected during a routine epidemiological survey of leprosis (three healthy and two infected females). Ovaries weighed approximately 0.06 kg, representing a gonadosomatic index of 6.9 ± 0.8%. The mean ovarian follicular population was 15,567.2 preantral follicles per ovarian pair. For most females, follicular population was mainly composed of primordial follicles. No major histological ovarian parameter was affected by M. leprae infection. All females presented high rates of follicular degeneration, regardless of M. leprae infection. In conclusion, we present original particularities regarding the qualitative and quantitative characteristics of the ovarian population of juvenile six-banded armadillos. Full article