N-Acetylcysteine improves oocyte quality through modulating the Nrf2 signaling pathway to ameliorate oxidative stress caused by repeated controlled ovarian hyperstimulation

Impact of repeated ovarian hyperstimulation on the reproductive function

One of six couples (17.5 % of the adult population) worldwide is affected by infertility during their lifetime. This number represents a substantial increase in the prevalence of this gynecological condition over the last decade. Ovulatory dysfunction and anovulation are the main causes of female infertility. Timed intercourse, intrauterine insemination, and assisted reproductive technology (ART), such as in vitro fertilization (IVF) and intracytoplasmic sperm injection (ICSI), are the most common interventions for infertile couples. Ovulation induction protocols for IVF/ICSI routinely use supraphysiological doses of gonadotropins to stimulate many preovulatory follicles. Animal and human studies suggested that ovarian hyperstimulation, alone or repeatedly, for ART cycles can induce changes in the immune response and increase the oxidative stress (OS) in the ovarian microenvironment. The consequences of repeated ovarian hyperstimulation on the human ovary remain poorly understood, particularly in relation to the effects of ovarian stimulation on the immune system and the potential for ovarian stimulation to cause OS. Animal studies have observed that repeated cycles of ovarian hyperstimulation can accelerate ovarian aging. Changes in ovarian hormone levels, accelerated loss of ovarian reserve, disorders in ovarian ultrastructure, ovarian senescence, and decreased reproductive performance represent possible long-term effects of repeated ovarian hyperstimulation. The short and long-term impact of the combination of antioxidant agents in ovarian hyperstimulation protocols in women undergoing ART must urgently be better understood. The recent increase in the number of ART and fertility preservation cycles may accelerate ovarian aging in these women, promoting consequences beyond the reproductive function and including health deterioration.

Effect of N-acetylcysteine on hair follicle changes in mouse model of cyclophosphamide-induced alopecia: histological and biochemical study

Chemotherapy-induced alopecia (CIA) represents one of the most severe side effects of chemotherapy, which forces some patients to reject cancer treatment. The exact pathophysiological mechanisms of CIA are not clearly understood, which makes it difficult to discover efficient preventive or therapeutic procedures for this adverse effect. N-acetylcysteine (NAC) has a strong antioxidant activity as it stimulates glutathione synthesis and acts as an oxygen radical scavenger. The current study tried to investigate the efficacy of NAC in preserving biochemical parameters and hair follicle structure against cyclophosphamide (CYP) administration. In total, 40 adult female C57BL/6 mice were induced to enter anagen by depilation (day 0) and divided into four groups: group I (control), group II (CYP) received a single dose of CYP [150 mg/kg body weight (B.W.)/intraperitoneal injection (IP)] at day 9, group III (CYP & NAC) received a single dose of CYP at day 9 as well as NAC (500 mg/kg B.W./day/IP) from day 6-16, and group IV (NAC) received NAC from day 6-16. CYP administration in group II induced an increase in malondialdehyde (MDA), decrease in superoxide dismutase (SOD), histological hair follicle dystrophy, disruption of follicular melanogenesis, overexpression of p53, and loss of ki67 immunoreactivity. NAC coadministration in group III reversed CYP-induced alterations in the biochemical parameters and preserved hair follicle structure, typical follicular melanin distribution as well as normal pattern of p53 and ki67 expression. These findings indicated that NAC could be used as an efficient and safe therapeutic option for hair loss induced by chemotherapy.

Bioactive Compounds Protect Mammalian Reproductive Cells from Xenobiotics and Heat Stress-Induced Oxidative Distress via Nrf2 Signaling Activation: A Narrative Review

Oxidative stress occurs when there is an imbalance between the production of reactive oxygen species (ROS) and the body's antioxidant defenses. It poses a significant threat to the physiological function of reproductive cells. Factors such as xenobiotics and heat can worsen this stress, leading to cellular damage and apoptosis, ultimately decreasing reproductive efficiency. The nuclear factor erythroid 2-related factor 2 (Nrf2) signaling pathway plays a crucial role in defending against oxidative stress and protecting reproductive cells via enhancing antioxidant responses. Dysregulation of Nrf2 signaling has been associated with infertility and suboptimal reproductive performance in mammals. Recent advancements in therapeutic interventions have underscored the critical role of Nrf2 in mitigating oxidative damage and restoring the functional integrity of reproductive cells. In this narrative review, we delineate the harmful effects of heat and xenobiotic-induced oxidative stress on reproductive cells and explain how Nrf2 signaling provides protection against these challenges. Recent studies have shown that activating the Nrf2 signaling pathway using various bioactive compounds can ameliorate heat stress and xenobiotic-induced oxidative distress and apoptosis in mammalian reproductive cells. By comprehensively analyzing the existing literature, we propose Nrf2 as a key therapeutic target for mitigating oxidative damage and apoptosis in reproductive cells caused by exposure to xenobiotic exposure and heat stress. Additionally, based on the synthesis of these findings, we discuss the potential of therapies focused on the Nrf2 signaling pathway to improve mammalian reproductive efficiency.

Altered Energy Metabolism, Mitochondrial Dysfunction, and Redox Imbalance Influencing Reproductive Performance in Granulosa Cells and Oocyte During Aging

Female fertility decreases during aging. The development of effective therapeutic strategies to address the age-related decline in oocyte quality and quantity and its accurate diagnosis remain major challenges. In this review, we summarize our current understanding of the study of aging and infertility, focusing primarily on the molecular basis of energy metabolism, mitochondrial function, and redox homeostasis in granulosa cells and oocytes, and discuss perspectives on future research directions. Mitochondria serve as a central hub sensing a multitude of physiological processes, including energy production, cellular redox homeostasis, aging, and senescence. Young granulosa cells favor glycolysis and actively produce pyruvate, NADPH, and other metabolites. Oocytes rely on oxidative phosphorylation fueled by nutrients, metabolites, and antioxidants provided by the adjacent granulosa cells. A reduced cellular energy metabolism phenotype, including both aerobic glycolysis and mitochondrial respiration, is characteristic of older female granulosa cells compared with younger female granulosa cells. Aged oocytes become more susceptible to oxidative damage to cells and mitochondria because of further depletion of antioxidant-dependent ROS scavenging systems. Molecular perturbations of gene expression caused by a subtle change in the follicular fluid microenvironment adversely affect energy metabolism and mitochondrial dynamics in granulosa cells and oocytes, further causing redox imbalance and accelerating aging and senescence. Furthermore, recent advances in technology are beginning to identify biofluid molecular markers that may influence follicular development and oocyte quality. Accumulating evidence suggests that redox imbalance caused by abnormal energy metabolism and/or mitochondrial dysfunction is closely linked to the pathophysiology of age-related subfertility.

NRF2 attenuation aggravates detrimental consequences of metabolic stress on cultured porcine parthenote embryos

The nuclear factor erythroid 2-related factor 2 (NRF2) is a crucial transcription factor that plays a central role in regulating oxidative stress pathways by binding antioxidant response elements, but its involvement in early embryo development remains largely unexplored. In this study, we demonstrated that NRF2 mRNA is expressed in porcine embryos from day 2 to day 7 of development, showing a decrease in abundance from day 2 to day 3, followed by an increase on day 5 and day 7. Comparable levels of NRF2 mRNA were observed between early-cleaving and more developmental competent embryos and late-cleaving and less developmental competent embryos on day 4 and day 5 of culture. Attenuation of NRF2 mRNA significantly decreased development of parthenote embryos to the blastocyst stage. When NRF2-attenuated embryos were cultured in presence of 3.5 mM or 7 mM glucose, development to the blastocyst stage was dramatically decreased in comparison to the control group (15.9% vs. 27.8% for 3.5 mM glucose, and 5.4% vs. 25.3% for 7 mM glucose). Supplementation of melatonin moderately improved the development of NRF2-attenuated embryos cultured in presence of 0.6 mM glucose. These findings highlight the importance of NRF2 in early embryo development, particularly in embryos cultured under metabolically stressful conditions.

Ovarian aging in humans: potential strategies for extending reproductive lifespan

Ovarian reserve is a term used to estimate the total number of immature follicles present in the ovaries. Between birth and menopause, there is a progressive decrease in the number of ovarian follicles. Ovarian aging is a continuous physiological phenomenon, with menopause being the clinical mark of the end of ovarian function. Genetics, measured as family history for age at the onset of menopause, is the main determinant. However, physical activity, diet, and lifestyle are important factors that can influence the age of menopause. The low estrogen levels after natural or premature menopause increased the risk for several diseases, resulting in increased mortality risk. Besides that, the decreasing ovarian reserve is associated to reduced fertility. In women with infertility undergoing in vitro fertilization, reduced markers of ovarian reserve, including antral follicular count and anti-Mullerian hormone, are the main indicators of reduced chances of becoming pregnant. Therefore, it becomes clear that the ovarian reserve has a central role in women's life, affecting fertility early in life and overall health later in life. Based on this, the ideal strategy for delaying ovarian aging should have the following characteristics: (1) be initiated in the presence of good ovarian reserve; (2) maintained for a long period; (3) have an action on the dynamics of primordial follicles, controlling the rate of activation and atresia; and (4) safe use in pre-conception, pregnancy, and lactation. In this review, we therefore discuss some of these strategies and its feasibility for preventing a decline in the ovarian reserve.

Mechanisms of and Potential Medications for Oxidative Stress in Ovarian Granulosa Cells: A Review

Granulosa cells are essential for follicle initiation and development, and their abnormal function or apoptosis is a crucial factor leading to follicular atresia. A state of oxidative stress occurs when the balance between the production of reactive oxygen species and the regulation of the antioxidant system is disturbed. Oxidative stress is one of the most important causes of the abnormal function and apoptosis of granulosa cells. Oxidative stress in granulosa cells causes female reproductive system diseases, such as polycystic ovary syndrome and premature ovarian failure. In recent years, studies have confirmed that the mechanism of oxidative stress in granulosa cells is closely linked to the PI3K-AKT signaling pathway, MAPK signaling pathway, FOXO axis, Nrf2 pathway, NF-κB signaling pathway, and mitophagy. It has been found that drugs such as sulforaphane, Periplaneta americana peptide, and resveratrol can mitigate the functional damage caused by oxidative stress on granulosa cells. This paper reviews some of the mechanisms involved in oxidative stress in granulosa cells and describes the mechanisms underlying the pharmacological treatment of oxidative stress in granulosa cells.

Efficacy of N-Acetylcysteine on Endometriosis-Related Pain, Size Reduction of Ovarian Endometriomas, and Fertility Outcomes

BACKGROUND

Endometriosis is a chronic, estrogen-dependent, inflammatory disease, whose pivotal symptoms are dysmenorrhea, dyspareunia, and chronic pelvic pain (CPP). Besides the usual medical treatments, recent evidence suggests there are potential benefits of oral N-acetylcysteine (NAC) on endometriotic lesions and pain. The primary objective of this prospective single-cohort study was to confirm the effectiveness of NAC in reducing endometriosis-related pain and the size of ovarian endometriomas. The secondary objective was to assess if NAC may play a role in improving fertility and reducing the Ca125 serum levels.

METHODS

Patients aged between 18-45 years old with a clinical/histological diagnosis of endometriosis and no current hormonal treatment or pregnancy were included in the study. All patients received quarterly oral NAC 600 mg, 3 tablets/day for 3 consecutive days of the week for 3 months. At baseline and after 3 months, dysmenorrhea, dyspareunia and CPP were assessed using the Visual Analog Scale score (VAS), while the size of the endometriomas was estimated through a transvaginal ultrasound. Analgesics (NSAIDs) intake, the serum levels of Ca125 and the desire for pregnancy were also investigated. Finally, the pregnancy rate of patients with reproductive desire was evaluated.

RESULTS

One hundred and twenty patients were recruited. The intensity of dysmenorrhea, dyspareunia and CPP significantly improved (p < 0.0001). The use of NSAIDs (p = 0.001), the size of the endometriomas (p < 0.0001) and the serum levels of Ca125 (p < 0.0001) significantly decreased. Among the 52 patients with reproductive desire, 39 successfully achieved pregnancy within 6 months of starting therapy (p = 0.001).

CONCLUSIONS

Oral NAC improves endometriosis-related pain and the size of endometriomas. Furthermore, it decreases Ca125 serum levels and may improve fertility in patients with endometriosis.

Kunling Wan improves oocyte quality by regulating the PKC/Keap1/Nrf2 pathway to inhibit oxidative damage caused by repeated controlled ovarian hyperstimulation

ETHNOPHARMACOLOGICAL RELEVANCE

Kunling Wan (KW) is a traditional Chinese medicine that is principally used for kidney deficiency, qi stagnation, and blood stasis, which are basic syndromes of infertility in China. KW can improve ovarian follicular development, ovarian function, and endometrial receptivity, which lead to improving pregnancy outcomes. Repeated controlled ovarian hyperstimulation (COH) reduces oocyte quality and results in a lower pregnancy rate. Whether KW has the potential to improve oocyte quality reduced by repeated COH has yet to be determined.

AIMS OF THE STUDY

The aim of this study wwas to evaluate the effect of KW on oocyte quality after damage due to repeated COH, and to investigate the mechanism(s) underlying the antioxidative protection of oocytes by mitochondria.

MATERIALS AND METHODS

Female Kunming mice were randomly divided into four groups: normal group, model (repeated COH) group, KW group, and N-acetylcysteine (NAC) group. We observed the morphology and quality of mitochondria, level of reactive oxygen species (ROS), and antioxidant enzymes activity of each group. Oocytes were treated with H2O2 and KW-containing serum, and we determined the antioxidant effects of KW on H2O2-treated oocytes and the mechanism involved in the regulation of Nrf2 in reducing oxidative damage.

RESULTS

Our results revealed that repeated COH caused oxidative damage and impaired oocyte mitochondrial function and structure, resulting in poor oocyte quality. KW pretreatment reduced oxidative damage by inhibiting ROS production and improving mitochondrial structure and function, thereby enhancing overall oocyte quality. In response to H2O2, KW activated the PKC/Keap1/Nrf2-signaling pathway and promoted the translocation of Nrf2 from the cytoplasm to the nucleus, which activated the expression of SOD and GSH-Px, and removed the excess ROS that caused the initial mitochondrial damage.

CONCLUSIONS

KW improved oocyte quality perturbed by repeated COH via reducing oxidative effects and improving mitochondrial function. The mechanism may be related to regulation of the PKC/Keap1/Nrf2 pathway in removing excess ROS.

NRF2 in dermo-cosmetic: From scientific knowledge to skin care products

The skin is the organ that is most susceptible to the impact of the exposome. Located at the interface with the external environment, it protects internal organs through the barrier function of the epidermis. It must adapt to the consequences of the harmful effects of solar radiation, the various chemical constituents of atmospheric pollution, and wounds associated with mechanical damage: oxidation, cytotoxicity, inflammation, and so forth. In this biological context, a capacity to adapt to the various stresses caused by the exposome is essential; otherwise, more or less serious conditions may develop accelerated aging, pigmentation disorders, atopy, psoriasis, and skin cancers. Nrf2-controlled pathways play a key role at this level. Nrf2 is a transcription factor that controls genes involved in oxidative stress protection and detoxification of chemicals. Its involvement in UV protection, reduction of inflammation in processes associated with healing, epidermal differentiation for barrier function, and hair regrowth, has been demonstrated. The modulation of Nrf2 in the skin may therefore constitute a skin protection or care strategy for certain dermatological stresses and disorders initiated or aggravated by the exposome. Nrf2 inducers can act through different modes of action. Keap1-dependent mechanisms include modification of the cysteine residues of Keap1 by (pro)electrophiles or prooxidants, and disruption of the Keap1-Nrf2 complex. Indirect mechanisms are suggested for numerous phytochemicals, acting on upstream pathways, or via hormesis. While developing novel and safe Nrf2 modulators for skin care may be challenging, new avenues can arise from natural compounds-based molecular modeling and emerging concepts such as epigenetic regulation.