Neurotrophins [nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), neurotrophin-3 (NT-3), and neurotrophin-4 (NT-4)] and glial cell line-derived neurotrophic factor (GDNF) are soluble polypeptide growth factors that are widely recognized for their roles in promoting cell growth, survival and differentiation in several classes of neurons. Outside the nervous system, neurotrophin (NT) and GDNF signaling events have substantial roles in various non-neural tissues, including the ovary. The molecular mechanisms that promote and regulate follicular development and oocyte maturation have been extensively investigated. However, most information has been obtained from animal models. Even though the fundamental process is highly similar across species, the paracrine regulation of ovarian function in humans remains poorly characterized. Therefore, this review aims to summarize the expression and functional roles of NTs and GDNF in human ovarian biology and disorders, and to describe and propose the development of novel strategies for diagnosing, treating and preventing related abnormalities. Relevant literature in the English language from 1990 to 2018 describing the role of NTs and GDNF in mammalian ovarian biology and phenotypes was comprehensively selected using PubMed, MEDLINE and Google Scholar. Studies have shown that the neurotrophins NGF, BDNF, NT-3 and NT-4 as well as GDNF and their functional receptors are expressed in the human ovary. Recently, gathered experimental data suggest putative roles for NT and GDNF signaling in the direct control of ovarian function, including follicle assembly, activation of the primordial follicles, follicular growth and development, oocyte maturation, steroidogenesis, ovulation and corpus luteum formation. Additionally, crosstalk occurs between these ovarian regulators and the endocrine signaling system. Dysregulation of the NT system may negatively affect ovarian function, leading to reproductive pathology (decreased ovarian reserve, polycystic ovary syndrome and endometriosis), female infertility and even epithelial ovarian cancers. A comprehensive understanding of the expression, actions and underlying molecular mechanisms of the NT/GDNF system in the human ovary is essential for novel approaches to therapeutic and diagnostic interventions in ovarian diseases and to develop more safe, effective methods of inducing ovulation in ART in the treatment of female infertility.

Mitochondria plays an essential role in regulating cellular metabolic homeostasis, proliferation/differentiation, and cell death. Mitochondrial dysfunction is implicated in many age-related pathologies. Evidence supports that the dysfunction of mitochondria and the decline of mitochondrial DNA copy number negatively affect ovarian aging. However, the mechanism of ovarian aging is still unclear. Treatment methods, including antioxidant applications, mitochondrial transplantation, emerging biomaterials, and advanced technologies, are being used to improve mitochondrial function and restore oocyte quality. This article reviews key evidence and research updates on mitochondrial damage in the pathogenesis of ovarian aging, emphasizing that mitochondrial damage may accelerate and lead to cellular senescence and ovarian aging, as well as exploring potential methods for using mitochondrial mechanisms to slow down aging and improve oocyte quality.

Polycystic ovary syndrome (PCOS) is a complex disorder associated with multiple metabolic disturbance, including defective glucose metabolism and insulin resistance. The altered metabolites caused by the related metabolic disturbance may affect ovarian follicles, which can be reflected in follicular fluid composition. The aim of this study is to investigate follicular fluid metabolic profiles in women with PCOS using an advanced sequential window acquisition of all theoretical fragment-ion spectra (SWATH) mass spectrometry. Nineteen women with PCOS and twenty-one healthy controls undergoing IVF/ET were recruited, and their follicular fluid samples were collected for metabolomic study. Follicular fluid metabolic profiles, including steroid hormones, free fatty acids, bioactive lipids, and amino acids were analyzed using the principal component analysis (PCA) and partial least squares to latent structure-discriminant analysis (PLS-DA) model. Levels of free fatty acids, 3-hydroxynonanoyl carnitine and eicosapentaenoic acid were significantly increased (P < 0.05), whereas those of bioactive lipids, lysophosphatidylcholines (LysoPC) (16:0), phytosphingosine, LysoPC (14:0) and LysoPC (18:0) were significantly decreased in women with PCOS (P < 0.05). Additionally, levels of steroid hormone deoxycorticosterone and two amino acids, phenylalanine and leucine were higher in the PCOS patients (P < 0.05). Women with PCOS display unique metabolic profiles in their follicular fluid, and this data may provide us with important biochemical information and metabolic signatures that enable a better understanding of the pathogenesis of PCOS.

Objective To evaluate the effect of electro-acupuncture (EA) in infertile patients with phlegm-dampness polycystic ovary syndrome-insulin resistance (PCOS-IR). Methods Seventy-six PCOS-IR patients who underwnet in vitro fertilization and embryo transfer (IVF-ET) were equally assigned to two groups according to a random digital table: the EA group and the control group, with 38 cases in each group. Before undergoing IVF, the two groups were treated with EA or pseudo-acupuncture, respectively, for 3 menstrual cycles. The intervention was 25 min twice a week until the day of oocyte collection. The selected acupoints were Zhongwan (RN 12), Tianshu (ST 25), Daheng (SP 15), Daimai (GB 26), Qihai (CV 6), Guanyuan (CV 4), and bilateral points including Xuehai (SP 10), Fenglong (ST 40), Zusanli (ST 36), and Yinlingquan (SP 9). Evaluation of phlegm-dampness syndrome score and IR score were carried out before and after treatment. Additionally, the number of oocytes retrieved, transplantable embryo rate, high-quality embryo rate, clinical pregnancy rate and live birth rate were compared between the two groups. Real-time polymerase chain reaction analysis was used to monitor the mRNA expression of the insulin receptor substrate (IRS-1), phosphatidylinositiol 3-kinase (PI3K) and glucose transport factor 4 (GLUT4) in ovarian granulosa cells. Results EA treatment reduced the phlegm-dampness syndrome score as well as the IR scores compared with the control group (P0.05). Moreover, the transplantable embryo rate [49.0% (284/580) vs. 41.9% (273/652)], high-quality embryo rate [36.6% (104/284) vs. 27.8% (76/273)], and live birth rate [50% (19/38) vs. 26.3% (10/38)] in the EA group were significantly higher than in the control group (P<0.05). Gene expression analyses revealed significantly elevated IRS-1, PI3K and GLUT4 mRNA in ovarian granulosa cells of the EA group compared with the control group (P<0.05). Conclusions EA may ameliorate the effects of phlegm-dampness syndrome and ovarian IR in PCOS-IR patients. Mechanistically, this effect might be through an upregulation of the IRS-1/PI3K/GLUT4 signaling pathway, which may result in improved oocyte quality and embryonic development potential. (Registration No. ChiCTR1800015453).

Ovarian ageing is a key factor in the decline of female fertility. It is primarily characterised by diminished oocyte quality, follicular depletion, and dysregulated hormone levels. In recent years, mitochondria-driven inflammation has emerged as a potential mechanism in ovarian ageing. Mitochondrial dysfunction results in the accumulation of reactive oxygen species (ROS) and the release of mitochondrial DNA (mtDNA), as well as the leakage of mitochondrial components and metabolites into the cytosol or extracellular space. These elements act as damage-associated molecular patterns (DAMPs), activating inflammasomes like NLRP3, thereby initiating and amplifying innate immune responses and contributing to sustained inflammation. Furthermore, an imbalance in mitochondrial quality control mechanisms can worsen the spread and persistence of inflammatory responses. In this study, we present a comprehensive overview of the signalling origins, molecular mechanisms of amplification, and key regulatory nodes involved in mitochondria-driven inflammation during ovarian ageing. Finally, we summarise potential therapeutic strategies targeting mitochondria-driven inflammation, offering novel perspectives and targets for delaying ovarian ageing and enhancing female reproductive health.

In our earlier study, we showed that the expression of microRNA‐221‐3p (miR‐221‐3p) was significantly lower in women of advanced age with diminished ovarian reserve (DOR) compared with young women with normal ovarian reserve (NOR). Therefore, in this study, we aimed to explore how miR‐221‐3p regulates apoptosis of granulosa cells and the pathogenesis of DOR. Bioinformatics prediction and dual‐luciferase reporter assay were conducted to identify the target gene of miR‐221‐3p. miR‐221‐3p expression was manipulated by transfecting KGN cells with miR‐221‐3p mimics, inhibitor, and negative control. Following transfection, apoptosis of granulosa cells was determined by flow cytometry, and the expression of the target gene was measured by quantitative real‐time polymerase chain reaction (qRT‐PCR) and western blot analysis (WB). In addition, the expression of the target gene in granulosa cells of DOR patients and NOR patients was measured. miR‐221‐3p were found to directly bind the 3ʹ untranslated region of Forkhead box O1 (FOXO1). Transfection with miR‐221‐3p mimics significantly decreased the apoptosis rate of KGN cells compared with transfection with miR‐221‐3p inhibitors. The expression level of miR‐221‐3p was negatively correlated with the messenger RNA and protein levels of the FOXO1 gene. Besides, FOXO1 expression was upregulated in DOR patients. In conclusion, these results provide evidence that downregulation of miR‐221‐3p expression promotes apoptosis of granulosa cells by upregulating FOXO1 expression, thus serving an important role in DOR pathogenesis.