Oxidative stress impairs oocyte quality and melatonin protects oocytes from free radical damage and improves fertilization rate

Improvement of oocyte quality through the SIRT signaling pathway

Background

Oocyte quality is one of the major deciding factors in female fertility competence.

Methods

PubMed database was searched for reviews by using the following keyword "oocyte quality" AND "Sirtuins". The methodological quality of each literature review was assessed using the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) 2020 statement.

Main Findings

Oxidative stress has been recognized as the mechanism attenuating oocyte quality. Increasing evidence from animal experiments and clinical studies has confirmed the protective roles of the sirtuin family in improving oocyte quality via an antioxidant effect.

Conclusion

The protective roles in the oocyte quality of the sirtuin family have been increasingly recognized.

Effects of selenium supplementation on Polycystic Ovarian Syndrome: a systematic review and meta-analysis on randomized clinical trials

BACKGROUND

This study provides a systematic review and meta-analysis of randomized controlled trials, which examined the effect of the selenium supplementation on polycystic ovary syndrome (PCOS).

METHODS

Confirmed studies related to selenium supplementation and PCOS were searched from the databases of EMBASE, PubMed and Web of Science. Data were reported as weighted mean difference (WMD) or standard mean difference (SMD) and associated 95% confidence intervals (CIs). Analysis was performed with Stata version 12.0.

RESULTS

A total of 389 cases (selenium group n = 195, control group n = 194) were included in this studies. This meta-analysis showed that selenium supplementation has a positive effect on TAC, and supplementation of selenium does not significantly improve the level of BMI, Weight, LDL, HDL, Triglycerides, Total Testosterone, HOMA-IR, NO, GSH, MDA and FPG.

CONCLUSION

Although selenium can improve TAC in PCOS patients, it has no significant effect on BMI, Total Testosterone, et al. In terms of the results of this meta-analysis, it is not recommended for patients with PCOS to use selenium as a regular trace element supplement. Based on the improving effect of selenium on TAC, supplementation of selenium may have a positive effect on improving follicle quality for some PCOS patients who have poor follicle quality caused by oxidative stress or who want to undergo IVF.

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.

Altered sperm fate in the reproductive tract milieu due to oxidative stress leads to sub-fertility in type 1 diabetes females: A Drosophila-based study

AIMS

Female sub-fertility, a prominent complication due to Type 1 diabetes (T1D), is generally attributed to disturbances in menstrual cycles and/or ovarian defects/disorders. T1D women, however, are high in oxidative stress, although the impact of the same on their reproduction and associated events remains unknown. Therefore, we assessed the repercussions of elevated oxidative stress on the sperm fate (storage/utilization) in the reproductive tract milieu of T1D females and their fertility using the Drosophila T1D model (Df[dilp1-5]), which lacks insulin-like peptides and displays reduced female fertility.

MAIN METHODS

We mated Df[dilp1-5] females to normal males and thereafter examined sperm storage and/or utilization in conjunction with oxidative stress parameters in mated Df[dilp1-5] females at different time points. Also, the impact of antioxidant (Amla or Vitamin C) supplementation on the above oxidative stress parameters in Df[dilp1-5] females and the consequences on their sperm and fertility levels were examined.

KEY FINDINGS

Df[dilp1-5] females showed elevated oxidative stress parameters and a few of their reproductive tract proteins are oxidatively modified. Also, these females stored significantly fewer sperm and also did not utilize sperm as efficiently as their controls. Surprisingly, amelioration of the oxidative stress in Df[dilp1-5] females' milieu through antioxidant (Amla or vitamin C) supplementation enhanced sperm storage and improved fertility.

SIGNIFICANCE

Hyperglycemia coupled with elevated oxidative stress within the female reproductive tract environment affects the sperm fate, thereby reducing female fertility in T1D. In addition, these findings suggest that antioxidant supplementation may substantially aid in the mitigation of sub-fertility in T1D females.

Unraveling female reproductive senescence to enhance healthy longevity

In a society where women often want successful careers and equal opportunities to men, the early nature of ovarian aging often forces women to make difficult life choices between career and family development. Fertility in women begins to decline after the age of 37 years and it is rare for pregnancies to occur after 45. This reproductive decline in women is inevitable and culminates in menopause, which is a major driver of age-related diseases. In a world where biomedical advances are leading to modifiable biological outcomes, it is time to focus on mitigating female reproductive senescence to maintain fertility and preserve age-related hormonal functions, with the goal of providing increased life choices and enhancing healthspan. To date, reproductive longevity research remains an understudied field. More needs to be done to unravel the biology of the ovarian follicles, which are the functional units of reproductive lifespan and are comprised of cell types including the oocyte (female gamete) and a group of specialized supporting somatic cells. Biological attempts to maintain the quality and quantity of follicles in animal models through manipulating pathways involved in aging can potentially prolong female reproductive lifespan and healthspan. Here, we summarize the molecular events driving ovarian aging and menopause and the interventional strategies to offset these events. Developing solutions to female reproductive senescence will open doors to discover ways to enhance true healthy longevity for both men and women.

The Antioxidant Auraptene Improves Aged Oocyte Quality and Embryo Development in Mice

Decrease in quality of postovulatory aged oocytes occurs due to oxidative stress and leads to low fertilization and development competence. It is one of the main causes that exerting detrimental effect on the success rate in assisted reproductive technology (ART). Auraptene (AUR), a citrus coumarin, has been reported to possess an antioxidant effects in other tissues. In this study, we aimed to confirm the potential of AUR to delay the oocyte aging process by alleviating oxidative stress. Superovulated mouse oocytes in metaphase of second meiosis (MII) were exposed to 0, 1 or 10 μM AUR for 12 h of in vitro aging. AUR addition to the culture medium recovered abnormal spindle and chromosome morphology and mitigated mitochondrial distribution and mitochondrial membrane potential (ΔΨ) in aged oocytes. AUR-treated aged oocytes also showed suppressed oxidative stress, with lower reactive oxygen species (ROS) levels, higher glutathione (GSH) levels and increased expression of several genes involved in antioxidation. Furthermore, AUR significantly elevated the fertilization and embryo developmental rates. Oocytes aged with 1 μM AUR exhibited morphokinetics that were very similar to those of the control group. Altogether, these data allowed us to conclude that AUR improved the quality of aged oocytes and suggest AUR as an effective clinical supplement candidate to prevent postovulatory aging.

Oxidative Stress-Induced Overactivation of Frog Eggs Triggers Calcium-Dependent Non-Apoptotic Cell Death

Excessive activation of frog eggs (overactivation) is a pathological process that renders eggs unfertilizable. Its physiological inducers are unknown. Previously, oxidative stress was shown to cause time- and dose-dependent overactivation of Xenopus laevis frog eggs. Here, we demonstrate that the oxidative stress-induced egg overactivation is a calcium-dependent phenomenon which can be attenuated in the presence of the selective calcium chelator BAPTA. Degradation of cyclin B2, which is known to be initiated by calcium transient in fertilized or parthenogenetically activated eggs, can also be observed in the overactivated eggs. Decline in mitochondrial membrane potential, ATP depletion and termination of protein synthesis manifest in the eggs within one hour of triggering overactivation. These intracellular events occur in the absence of caspase activation. Furthermore, plasma membrane integrity is compromised in the overactivated eggs, as evidenced by ATP leakage and egg swelling. In sum, our data demonstrate that oxidative stress-induced overactivation of frog eggs causes fast and dramatic disruption of cellular homeostasis, resulting in robust and expedited cell death by a calcium-dependent non-apoptotic mechanism.

Oxidative Stress-Related Signaling Pathways Predict Oocytes' Fertilization In Vitro and Embryo Quality

Oocyte development and fertilization are largely influenced by the microenvironment of the follicular fluid (FF), and the exploration of its molecular/metabolic composition may help in improving in vitro fertilization (IVF) outcomes. Here, the concentrations of molecules related to oxidative stress/inflammation were measured in FF from follicles at oocyte retrieval during IVF. Here, the FF antioxidant potential was correlated with the number of retrieved/mature oocytes and the number of fertilized ones. FF collected from the follicles of normal fertilized oocytes presented an elevated antioxidant capability, lower levels of pro-inflammatory molecules (i.e., IL-6, IL-8, IL-12, TGF-β, and HIF-1α), and a higher IL-10 concentration. FF samples from follicles at oocyte retrieval that resulted in top-quality embryos displayed a peculiar antioxidant capability and a further decrease in proinflammatory molecules when compared with FF, giving rise to poor-quality embryos. Finally, pro-inflammatory molecules were lower and accompanied by a high antioxidant capability in samples giving rise to successful embryo implantation. The antioxidant capability and IL-10 displayed a good predictive ability for fertilization and embryo quality. Overall, our data showed the great influence of oxidative stress on the oocytes' fertilization, and shed light on the importance of controlling the inflammatory and oxidative status of FF to obtain good-quality embryos with significant implantation potential.

Melatonin in Endometriosis: Mechanistic Understanding and Clinical Insight

Endometriosis is defined as the development of endometrial glands and stroma outside the uterine cavity. Pathophysiology of this disease includes abnormal hormone profiles, cell survival, migration, invasion, angiogenesis, oxidative stress, immunology, and inflammation. Melatonin is a neuroendocrine hormone that is synthesized and released primarily at night from the mammalian pineal gland. Increasing evidence has revealed that melatonin can be synthesized and secreted from multiple extra-pineal tissues where it regulates immune response, inflammation, and angiogenesis locally. Melatonin receptors are expressed in the uterus, and the therapeutic effects of melatonin on endometriosis and other reproductive disorders have been reported. In this review, key information related to the metabolism of melatonin and its biological effects is summarized. Furthermore, the latest in vitro and in vivo findings are highlighted to evaluate the pleiotropic functions of melatonin, as well as to summarize its physiological and pathological effects and treatment potential in endometriosis. Moreover, the pharmacological and therapeutic benefits derived from the administration of exogenous melatonin on reproductive system-related disease are discussed to support the potential of melatonin supplements toward the development of endometriosis. More clinical trials are needed to confirm its therapeutic effects and safety.

Molecular Clues to Understanding Causes of Human-Assisted Reproduction Treatment Failures and Possible Treatment Options

More than forty years after the first birth following in vitro fertilization (IVF), the success rates of IVF and of IVF-derived assisted reproduction techniques (ART) still remain relatively low. Interindividual differences between infertile couples and the nature of the problems underlying their infertility appear to be underestimated nowadays. Consequently, the molecular basis of each couple’s reproductive function and of its disturbances is needed to offer an individualized diagnostic and therapeutic approaches to each couple, instead of applying a standard or minimally adapted protocols to everybody. Interindividual differences include sperm and oocyte function and health status, early (preimplantation) embryonic development, the optimal window of uterine receptivity for the implanting embryo, the function of the corpus luteum as the main source of progesterone production during the first days of pregnancy, the timing of the subsequent luteoplacental shift in progesterone production, and aberrant reactions of the uterine immune cells to the implanting and recently implanted embryos. In this article, the molecular basis that underlies each of these abnormalities is reviewed and discussed, with the aim to design specific treatment options to be used for each of them.

The role of oxidative stress in ovarian aging: a review

Ovarian aging refers to the process by which ovarian function declines until eventual failure. The pathogenesis of ovarian aging is complex and diverse; oxidative stress (OS) is considered to be a key factor. This review focuses on the fact that OS status accelerates the ovarian aging process by promoting apoptosis, inflammation, mitochondrial damage, telomere shortening and biomacromolecular damage. Current evidence suggests that aging, smoking, high-sugar diets, pressure, superovulation, chemotherapeutic agents and industrial pollutants can be factors that accelerate ovarian aging by exacerbating OS status. In addition, we review the role of nuclear factor E2-related factor 2 (Nrf2), Sirtuin (Sirt), mitogen-activated protein kinase (MAPK), protein kinase B (AKT), Forkhead box O (FoxO) and Klotho signaling pathways during the process of ovarian aging. We also explore the role of antioxidant therapies such as melatonin, vitamins, stem cell therapies, antioxidant monomers and Traditional Chinese Medicine (TCM), and investigate the roles of these supplements with respect to the reduction of OS and the improvement of ovarian function. This review provides a rationale for antioxidant therapy to improve ovarian aging.

2,3,5,4′-Tetrahydroxystilbene-2-O-β-D-Glucoside improves female ovarian aging

Reduced fertility associated with normal aging may reflect the over-maturity of oocytes. It is increasingly important to reduce aging-induced infertility since recent trends show people marrying at later ages. 2,3,5,4′-Tetrahydroxystilbene-2-O-β-D-glucoside (THSG), a polyphenol extracted from Polygonum multiflorum, has been reported to have anti-inflammatory and anti-aging properties. To evaluate whether THSG can reduce aging-related ovarian damage in a female mouse model of aging, THSG was administered by gavage at a dose of 10 mg/kg twice weekly, starting at 4 weeks of age in a group of young mice. In addition, the effect of THSG in a group of aged mice was also studied in mice starting at 24 weeks of age. The number of oocytes in the THSG-fed group was higher than in the untreated control group. Although the percentage of secondary polar bodies (PB2) decreased during aging in the THSG-fed group, it decreased much more slowly than in the age-matched control group. THSG administration increased the quality of ovaries in young mice becoming aged. Western blotting analyses also indicated that CYP19, PR-B, and ER-β expressions were significantly increased in 36-week-old mice. THSG also increased oocyte numbers in aged mice compared to mice without THSG fed. Studies of qPCR and immunohistochemistry (IHC) analyses of ovaries in the aged mice groups were conducted. THSG increased gene expression of anti-Müllerian hormone (AMH), a biomarker of oocyte number, and protein accumulation in 40-week-old mice. THSG increased the expression of pgc1α and atp6, mitochondrial biogenesis-related genes, and their protein expression. THSG also attenuated the fading rate of CYP11a and CYP19 associated with sex hormone synthesis. And THSG maintains a high level of ER-β expression, thereby enhancing the sensitivity of estrogen. Our findings indicated that THSG increased or extended gene expression involved in ovarian maintenance and rejuvenation in young and aged mice. On the other hand, THSG treatments significantly maintained oocyte quantity and quality in both groups of young and aged mice compared to each age-matched control group. In conclusion, THSG can delay aging-related menopause, and the antioxidant properties of THSG may make it suitable for preventing aging-induced infertility.

Ramelteon Reduces Oxidative Stress by Maintenance of Lipid Homeostasis in Porcine Oocytes

This study aimed to determine the underlying mechanism of ramelteon on the competence of oocyte and subsequent embryo development in pigs during in vitro maturation (IVM). Our results showed that the cumulus expansion index was significantly lower in the control group compared to the ramelteon groups (p < 0.05). Moreover, supplementation of 10−11 and 10−9 M ramelteon significantly increased the cumulus expansion and development-related genes expression, and reduced apoptosis in cumulus cells (p < 0.05). In oocytes, the nuclear maturation rate was significantly improved in 10−11, 10−9, and 10−7 M ramelteon groups compared to the control (p < 0.05). Additionally, the level of intracellular GSH was significantly increased and ROS was significantly decreased in ramelteon-supplemented groups, and the gene expression of oocyte development and apoptosis were significantly up- and down-regulated by 10−11 and 10−9 M ramelteon (p < 0.05), respectively. The immunofluorescence results showed that the protein levels of GDF9, BMP15, SOD1, CDK1, and PGC1α were significantly increased by 10−11 M ramelteon compared to the control (p < 0.05). Although there was no significant difference in cleavage rate, the blastocyst formation rate, total cell numbers, and hatching/-ed rate were significantly improved in 10−11 M ramelteon group compared to the control (p < 0.05). Furthermore, embryo development, hatching, and mitochondrial biogenesis-related genes were dramatically up-regulated by 10−11 M ramelteon (p < 0.05). In addition, the activities of lipogenesis and lipolysis in oocytes were dramatically increased by 10−11 M ramelteon compared to the control (p < 0.05). In conclusion, supplementation of 10−11 M ramelteon during IVM improved the oocyte maturation and subsequent embryo development by reducing oxidative stress and maintenance of lipid homeostasis.

Importance of Antioxidant Supplementation during In Vitro Maturation of Mammalian Oocytes

The in vitro embryo production (IVEP) technique is widely used in the field of reproductive biology. In vitro maturation (IVM) is the first and most critical step of IVEP, during which, the oocyte is matured in an artificial maturation medium under strict laboratory conditions. Despite all of the progress in the field of IVEP, the quality of in vitro matured oocytes remains inferior to that of those matured in vivo. The accumulation of substantial amounts of reactive oxygen species (ROS) within oocytes during IVM has been regarded as one of the main factors altering oocyte quality. One of the most promising approaches to overcome ROS accumulation within oocytes is the supplementation of oocyte IVM medium with antioxidants. In this article, we discuss recent advancements depicting the adverse effects of ROS on mammalian oocytes. We also discuss the potential use of antioxidants and their effect on both oocyte quality and IVM rate.

Pre-Treatment Physical Activity Could Positively Influence Pregnancy Rates in IVF despite the Induced Oxidative Stress: A Cohort Study on Salivary 8-Hydroxy-2'-deoxyguanosine

(1) Background: This study was designed to define whether pretreatment habitual physical activity (PA)-induced oxidative stress (OS) influences outcome measures by using 8-hydroxy-2′-deoxyguanosine (8-OHdG) in saliva samples of patients undergoing in vitro fertilization (IVF). (2) Method: In this cohort study, samples were obtained from 26 patients (age: 34.6 ± 5.5 years, BMI: 25.3 ± 5.1, infertility: 51.0 ± 28.7 months) before the treatment and a follow-up of outcome measures of IVF/ICSI. The 8-OHdG was evaluated by Abcam’s ELISA (ab201734), PA patterns by GPAQ-H and ActiGraph GT3X; (3) Results: The number of matured oocytes was positively influenced by the GPAQ-H recreation MET (R2 = 0.367, F = 10.994, p = 0.004; β = 0.005, p = 0.004, B Constant = 4.604) and a positive significant relationship (R2 = 0.757, F = 17.692, p < 0.001, B Constant = 1.342) was found with GPAQ-H recreational PA MET (β = 0.004, p < 0.001), and Grade 1 embryos and higher very vigorous activity (GT3X) were accompanied (R2 = 0.958, F = 408.479, p < 0.001) by higher ß-hCG levels (β = 63.703, p ≤ 0.001). Unanticipated positive correlation between 8-OHdG and ß-hCG level (R = 0.467, p = 0.028) was noticed, and there were significant differences in 8-OHdG in biochemical pregnancies (pregnant: 54.82 ± 35.56 ng/mL, non-pregnant: 30.06 ± 10.40 ng/mL, p = 0.022) as well. (4) Conclusions: Pretreatment PA could positively influence reproductive performance in IVF/ICSI despite the induced OS. However, a more sensitive biomarker and the recommended amount of activity should be further investigated.

Oxidative Stress and Human Ovarian Response—From Somatic Ovarian Cells to Oocytes Damage: A Clinical Comprehensive Narrative Review

Basic scientific research on human reproduction and oxidative damage has been extensively performed; however, a more clinical view is still lacking. As a result, exhaustive data on the influence of oxidative stress on human ovarian response and, consequently, on fertility are still lacking. This narrative review aims at summarizing the role of oxidative stress in different conditions associated to female infertility and to list some of the main antioxidant agents. A systematic literature search was performed in May 2022 to retrieve studies regarding the oxidative stress and the human ovarian response from somatic ovarian cells to oocytes damage. Only human studies were included and the authors focused their review, in particular, on clinical implications in order to define a new research perspective on the assessment of any eventual strategy to preserve women’s fertility. Thereby, the authors evaluated the contribution of DNA repair pathways in improving women’s fertility by reducing the DNA damage associated with aging or diseases, such as endometriosis or polycystic ovary syndrome, and eventually, in prolonging the reproductive lifespan after cancer treatment.

Exogenous Melatonin Directly and Indirectly Influences Sheep Oocytes

Understanding whether and how melatonin (MT) may impact sheep oocyte development competence is central to our ability to predict how sheep oocytes will respond to artificially regulated estrus. Implanting MT can make sheep enter estrus during the non-breeding season. One study found that the blastocyst rate increased under MT treatment, while another found that the blastocyst rate decreased. Therefore, we conducted a meta-analysis of MT directly and indirectly influencing sheep oocytes. A total of 433 articles were collected from which 20 articles and 34 treatments were finally selected. A method for estimating the default value was established for the litter size analysis. We found that exogenous MT add into in vitro maturation medium was positively related to the blastocyst rate in the lab. However, subcutaneous implanting MT did not affect the in vivo ovulation rate, fertilization rate, blastocyst rate, or pregnancy rate at farm. MT did not affect the in vitro cleavage rate. However, MT improved the in vivo cleavage rate. We hypothesized that implanted MT could increase the concentration of MT in oviduct fluid in vivo, and also that in vitro MT could increase the early cleavage rate of sheep zygotes without affecting the total cleavage rate. In the analysis of oocyte apoptosis caused by injury, the results suggested that pyroptosis would be more suitable for further research. MT produces responses in all body organs, and thus implanting of MT during non-breeding seasons should consider the effect on animal welfare.

Effects of Melatonin on the Transcriptome of Human Granulosa Cells, Fertilization and Blastocyst Formation

Melatonin is a promising reagent that can improve assisted reproductive technology (ART) outcomes in infertility patients. However, melatonin is not effective for all infertile patients, and it remains unclear for which patients melatonin would be effective. This study examined the effects of melatonin on ART outcomes and examined its mechanisms. Melatonin increased the fertilization rate in patients whose fertilization rates in the previous cycle were less than 50%, but not in patients whose fertilization rates were more than 50% in the previous cycle. Melatonin increased the blastocyst formation rate in patients whose embryo development rates in the previous cycle were less than 50%, but not in patients whose embryo development rates were more than 50% in the previous cycle. To clarify its mechanisms, transcriptome changes by melatonin treatment in granulosa cells (GCs) of the patients were examined by RNA-sequence. Melatonin treatment altered the transcriptomes of GCs of patients with poor ART outcomes so that they were similar to the transcriptomes of patients with good ART outcomes. The altered genes were associated with the inhibition of cell death and T-cell activity, and the activation of steroidogenesis and angiogenesis. Melatonin treatment was effective for patients with poor fertilization rates and poor embryo development rates in the previous ART cycle. Melatonin alters the GCs transcriptome and, thus, their functions, and this could improve the oocyte quality, leading to good ART outcomes.

Effects of Intramuscular Injections of Vitamins AD3E and C in Combination on Fertility, Immunity, and Proteomic and Transcriptomic Analyses of Dairy Cows during Early Gestation

This research aimed to investigate the effects of the intramuscular injection of vitamins AD3E and C in combination immediately before the estrus synchronization program (the Ovsynch program) on conception and pregnancy rates, blood parameters, serum biochemical properties, immune systems, antioxidant parameters, and proteomic and transcriptomic analyses during early gestation in dairy cows. Forty nonlactating multiparous cows were randomly assigned to one of four treatments: (1) C: control with normal saline injection; (2) VAD3E: a single intramuscular injection (I/M) of vitamin AD3E; (3) VAD3EC: injection of both vitamins AD3E and C; (4) VC: a single dose of vitamin C. Blood and serum samples were taken immediately at day 0 (before AI), day 7, and day 14 (after AI for 5 days) from the coccygeal vein. Generally, injections of AD3E and C in combination had no effect on the rate of conception or pregnancy. However, they improved hematological parameters and immune and antioxidant activities. Serum samples were analyzed using LC-MS/MS, and 8190 proteins were identified. Five proteins were successfully validated using the quantitative real-time reverse transcription PCR (qRT-PCR) method. This study found that lymphocyte-specific protein 1 (LSP1, A0A3Q1M894) could be used as a protein biomarker for cows administrated with vitamins AD3E and C.

Follicular fluid 8-Hydroxy-2-Deoxyguanosine (8-OHdG) as biomarker for oxidative stress in intracytoplasmic sperm injection

Oxidative stress (OS) is a situation that occurs as a result of un-equilibrium between reactive oxygen species (ROS) formation and the antioxidant defence system. 8-hydroxy-2-deoxyguanosine (8-OHdG), an oxidized form of deoxyguanosine, is found in higher levels in aging oocytes. In this cross-sectional study, we aimed to evaluate the effect of 8-OHdG on the intracytoplasmic sperm injection (ICSI). Follicular fluid (FF) samples were taken after removing the oocyte for later analysis of 8-OHdG. The couples participants were categorized according to the cause of subfertility into three groups (female factor, malefactor, and unexplained infertility). Further division according to pregnancy state was done to evaluate the precise role of 8-OHdG on pregnancy state and ICSI outcome. Result : This study showed that the 8-OHdG levels significantly higher in non-pregnant women (p<0.05). Correlation study showed that 8-OHdG level in follicular fluid is negatively correlating with the number of retrieved oocytes, metaphase two oocytes (MII), fertilized oocytes (2PN = two pronuclei), cleaved zygotes, good quality embryos, and the difference was statistically significant (p<0.05). Conclusion: The study revealed that the 8-OHdG level in follicular fluid negatively influences ICSI outcome and it is higher in non-pregnant women. J. Med. Invest. 69 : 112-116, February, 2022.

The Reproductive Functions of the Human Brain Regions: A Systematic Review

Reproduction remains a vital characteristic of living things necessary for survival and continuity. Specific brain regions and structures are responsible for regulating the different aspects of human reproduction. This study systematically reviewed the brain regions that play structural, hormonal and physiological roles in controlling the various aspects of human reproduction from puberty, sexual function, gametogenesis, childbirth and fertility to infertility to inform advancement in research and therapeutic interventions in human reproductive disorders. A systematic literature search of online databases (MEDLINE, Europe PMC and Google Scholar) was made using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines for observational and cross-sectional studies providing evidence for the role(s) of the brain region in human reproduction from the year 2011-2021. Out of 141 articles found, 15 studies met the inclusion criteria, including six cross-sectional and nine randomised controlled trials. The study acknowledged the roles of the pituitary gland, hypothalamus and pineal gland, widely known for regulating the human reproductive system in a gender-based approach while highlighting essential gaps and opportunities for future research. This review provides a 10-year update and overview of the role of different brain regions in human reproduction and will stimulate future research in human reproduction.

Melatonin Regulates Lipid Metabolism in Porcine Cumulus–Oocyte Complexes via the Melatonin Receptor 2

Previous studies suggest that the inclusion of melatonin (MTn) in in vitro maturation protocols improves the developmental competence of oocytes by scavenging reactive oxygen species (ROS). However, the molecular mechanisms integrating melatonin receptor (MT)-mediated lipid metabolism and redox signaling during in vitro cumulus–oocyte complex (COC) development still remain unclear. Here, we aimed to elucidate the potential role of MTn receptors in lipid metabolic adjustments during in vitro porcine COC development. We observed that MTn-mediated Gsα–cAMP/PKA signaling facilitated lipolysis primarily through the MT2 receptor and subsequently increased fatty acid (FA) release by hydrolyzing intracellular triglycerides (TGs) in cumulus cells. Furthermore, CD36 was a critical FA transporter that transported available FAs from cumulus cells to oocytes and promoted de novo TG synthesis in the latter. In addition, MTn regulated lipogenesis and intracellular lipolysis to maintain lipid homeostasis and limit ROS production, thereby supporting oocyte cytoplasmic maturation and the subsequent embryo development. Taken together, these findings provide insight into the possible mechanism integrating MT2-mediated lipid homeostasis and redox signaling, which limits ROS production during in vitro COC development. Therefore, understanding the dynamics of the interactions between lipid homeostasis and redox signaling driven by MT2 is necessary in order to predict drug targets and the effects of therapeutics used to improve female reproductive health.

Chrysin reduces inflammation and oxidative stress and improves ovarian function in D-gal-induced premature ovarian failure

Premature ovarian failure (POF), a frequently occurring pathology. Chrysin has antioxidant, anti-inflammatory, anti-apoptotic and other pharmacological activities. This study was designed to detect the effect of Chrysin on POF. The establishment of POF was depended on the subcutaneous injection of D-gal (200 mg/kg/d). With the adoption of ELISA, the levels of hormones and release of inflammatory cytokines were assayed. The expression of MDA, GSH-px, SOD and ROS was evaluated with corresponding kits. In addition, the pathological changes of ovary and apoptosis of ovarian granulosa cells in D-gal-induced mice were detected using H&E staining and TUNEL, respectively. Moreover, the levels of FSH receptor and apoptosis-related proteins were measured with western blot. Finally, ERβ expression was measured with RT-qPCR and western blot. In this study, we found that chrysin regulated the expression of hormones and weight of D-gal-induced mice. It was also found that chrysin inhibited the inflammation and oxidative stress in mice with D-gal induction. In addition, the number and advancement of follicle in D-gal-induced mice treated with chrysin revealed that chrysin could improve the ovarian function of mice with POF. Furthermore, chrysin exhibited inhibitory effects on the apoptosis of ovarian granulosa cells in D-gal-induced mice. More importantly, chrysin molecule targeted ERβ and activated ERβ expression in POF. Overall, Chrysin reduces inflammation and oxidative stress and improves ovarian function in D-gal-induced premature ovarian failure, suggesting that chrysin is valuable for the treatment of POF.

Melatonin prevents oocyte deterioration due to cotinine exposure in mice

Levels of cotinine, a major metabolite of nicotine, have been positively correlated with risks of cigarette smoking-related diseases. Melatonin is synthesized by the pineal gland and has been demonstrated to be beneficial to oocyte maturation due to its antioxidative activity. In this study, we investigated the effects of cotinine on mouse oocyte meiosis and the protective roles of melatonin in vitro and in vivo. The results showed that cotinine exposure caused defects in the first polar body extrusion and reduced parthenogenetic activation in in vitro-matured oocytes. Additionally, cotinine exposure increased the level of oxidative stress, which resulted in aberrant actin distribution, abnormal spindle morphology, chromosome misalignment, and even oocyte aneuploidy. Simultaneously, cotinine exposure decreased the mitochondrial membrane potential and antioxidant gene expression and increased apoptosis-related gene expression. However, all these toxic effects of cotinine could be reversed after the addition of melatonin, and the mechanism may be a decrease in reactive oxygen species production. In conclusion, cotinine causes poor oocyte quality, which could be rescued by melatonin supplementation during meiotic maturation in mouse oocytes.

Oxidative stress and DNA damage status in couples undergoing in vitro fertilization treatment

This study examined the status of oxidative stress in 599 couples undertaking in vitro fertilization (IVF) treatment and its association with reproductive hormones, smoking, and outcomes. Oxidative stress biomarkers such as malondialdehyde, 8-hydroxy-2-deoxyguanosine, hydrogen peroxide (H₂O₂), catalase (CAT), and total antioxidant capacity (TAC) were determined in follicular fluid and seminal plasma. Tail moment (TM) was used to evaluate DNA damage in the sperm and granulosa cells. Reproductive hormones in serum and cotinine (COT) in urine, follicular fluid, and seminal plasma samples were determined. Separate multivariate linear regression was used to assess associations between levels of each oxidative stress biomarker and each hormone and smoking parameter (modeled as natural log-transformed). The findings indicate that some oxidative stress and DNA damage biomarkers played a role in disrupting certain reproductive hormones in women and their male partners either by overproducing reactive oxygen species or reducing antioxidant defense capacity. Although women were nonsmokers, COT levels > 50 and 10 µg/L in urine and follicular were observed in 5.7 and 1.7%, respectively. Levels of follicular fluid COT were positively associated with H₂O₂ and TM. We used log-binomial multivariate regression to estimate relative risks for the association between oxidative stress/DNA damage and IVF binary outcomes (fertilization rate > 50%, biochemical pregnancy, clinical pregnancy, and live birth). An increase in the CAT levels of follicular fluid was associated with a 48 and 41% decrease in the risk of poor fertilization rate (≤50%) and unsuccessful live birth, respectively. After the models were adjusted for hormonal factors, the associations remained the same, except that the elevated TAC in follicular fluid became significantly associated with a decrease of 42% in the risk of poor fertilization rate (≤50%). The higher antioxidant activity (CAT and TAC) in follicular fluid might positively impact specific IVF outcomes.

Melatonin as the Cornerstone of Neuroimmunoendocrinology

Much attention has been recently drawn to studying melatonin – a hormone whose synthesis was first found in the epiphysis (pineal gland). This interest can be due to discovering the role of melatonin in numerous physiological processes. It was the discovery of melatonin synthesis in endocrine organs (pineal gland), neural structures (Purkinje cells in the cerebellum, retinal photoreceptors), and immunocompetent cells (T lymphocytes, NK cells, mast cells) that triggered the evolution of new approaches to the unifield signal regulation of homeostasis, which, at the turn of the 21st century, lead to the creation of a new integral biomedical discipline — neuroimmunoendocrinology. While numerous hormones have been verified over the last decade outside the “classical” locations of their formation, melatonin occupies an exclusive position with regard to the diversity of locations where it is synthesized and secreted. This review provides an overview and discussion of the major data regarding the role of melatonin in various physiological and pathological processes, which affords grounds for considering melatonin as the “cornerstone” on which neuroimmunoendocrinology has been built as an integral concept of homeostasis regulation.

The Key Role of Peroxisomes in Follicular Growth, Oocyte Maturation, Ovulation, and Steroid Biosynthesis

The absence of peroxisomes can cause disease in the human reproductive system, including the ovaries. The available peroxisomal gene-knockout female mouse models, which exhibit pathological changes in the ovary and reduced fertility, are listed in this review. Our review article provides the first systematic presentation of peroxisomal regulation and its possible functions in the ovary. Our immunofluorescence results reveal that peroxisomes are present in all cell types in the ovary; however, peroxisomes exhibit different numerical abundances and strong heterogeneity in their protein composition among distinct ovarian cell types. The peroxisomal compartment is strongly altered during follicular development and during oocyte maturation, which suggests that peroxisomes play protective roles in oocytes against oxidative stress and lipotoxicity during ovulation and in the survival of oocytes before conception. In addition, the peroxisomal compartment is involved in steroid synthesis, and peroxisomal dysfunction leads to disorder in the sexual hormone production process. However, an understanding of the cellular and molecular mechanisms underlying these physiological and pathological processes is lacking. To date, no effective treatment for peroxisome-related disease has been developed, and only supportive methods are available. Thus, further investigation is needed to resolve peroxisome deficiency in the ovary and eventually promote female fertility.

The boosting effects of melatonin on the expression of related genes to oocyte maturation and antioxidant pathways: a polycystic ovary syndrome- mouse model

Background

Melatonin, as a free radical scavenger exhibiting genomic actions, regulates the antioxidant genes expression and apoptosis mechanisms. In polycystic ovary syndrome (PCOS) patients, an imbalance between free radicals and antioxidants in follicular fluid leads to oxidative stress, aberrant folliculogenesis, and intrinsic defects in PCOS oocytes. In this experimental mouse model study, oocytes of PCOS and the control groups were cultured in different melatonin concentrations (10− 5, 10− 6, and 10− 7 M) to investigate the expression of oocyte maturation-related genes (Gdf9/Bmp15), antioxidant-related genes (Gpx1/Sod1), apoptotic biomarkers (Bcl2/Bax) and total intracellular ROS levels.

Results

Gdf9 and Bmp15, Gpx1 and Sod1 were up-regulated in PCOS and control oocytes cultured in all melatonin concentrations compared to those cultured in IVM basal medium (P < 0.05). A significant decrease in the total ROS level was observed in all groups cultured in the supplemented cultures. Melatonin increased Bcl2 and decreased Bax gene expression in PCOS and control oocytes compared to non-treated oocytes.

Conclusions

Melatonin increased antioxidant gene expression and regulated the apoptosis pathway, effectively reducing the adverse effects of culture conditions on PCOS oocytes. Furthermore, it influenced the expression of oocyte maturation-related genes in PCOS, providing valuable support during the IVM process.

Impact of sleep patterns upon female neuroendocrinology and reproductive outcomes: a comprehensive review

Sleep is vital to human bodily function. Growing evidence indicates that sleep deprivation, disruption, dysrhythmia, and disorders are associated with impaired reproductive function and poor clinical outcomes in women. These associations are largely mediated by molecular-genetic and hormonal pathways, which are crucial for the complex and time sensitive processes of hormone synthesis/secretion, folliculogenesis, ovulation, fertilization, implantation, and menstruation. Pathologic sleep patterns are closely linked to menstrual irregularity, polycystic ovarian syndrome, premature ovarian insufficiency, sub/infertility, and early pregnancy loss. Measures of success with assisted reproductive technology are also lower among women who engage in shift work, or experience sleep disruption or short sleep duration. Extremes of sleep duration, poor sleep quality, sleep disordered breathing, and shift work are also associated with several harmful conditions in pregnancy, including gestational diabetes and hypertensive disorders. While accumulating evidence implicates pathologic sleep patterns in impaired reproductive function and poor reproductive outcomes, additional research is needed to determine causality and propose therapeutic interventions.

Placental Dysfunction in Assisted Reproductive Pregnancies: Perinatal, Neonatal and Adult Life Outcomes

Obstetric and newborn outcomes of assisted reproductive technology (ART) pregnancies are associated with significative prevalence of maternal and neonatal adverse health conditions, such as cardiovascular and metabolic diseases. These data are interpreted as anomalies in placentation involving a dysregulation of several molecular factors and pathways. It is not clear which extent of the observed placental alterations are the result of ART and which originate from infertility itself. These two aspects probably act synergically for the final obstetric risk. Data show that mechanisms of inappropriate trophoblast invasion and consequent altered vascular remodeling sustain several clinical conditions, leading to obstetric and perinatal risks often found in ART pregnancies, such as preeclampsia, fetal growth restriction and placenta previa or accreta. The roles of factors such as VEGF, GATA3, PIGF, sFLT-1, sEndoglin, EGFL7, melatonin and of ART conditions, such as short or long embryo cultures, trophectoderm biopsy, embryo cryopreservation, and supraphysiologic endometrium preparation, are discussed. Inflammatory local conditions and epigenetic influence on embryos of ART procedures are important research topics since they may have important consequences on obstetric risk. Prevention and treatment of these conditions represent new frontiers for clinicians and biologists involved in ART, and synergic actions with researchers at molecular levels are advocated.

Serum 8-Hydroxy-2'-deoxyguanosine Predicts Severity and Prognosis of Patients with Acute Exacerbation of Chronic Obstructive Pulmonary Disease

BACKGROUND

Oxidative stress is involved in the pathogenesis of chronic obstructive pulmonary disease (COPD). 8-Hydroxy-2'-deoxyguanosine (8-OHdG) is recognized as a biomarker of oxidative stress and is implicated in several pulmonary diseases. Nonetheless, the role of 8-OHdG remains unclear in COPD patients. This research aimed to evaluate the correlations between serum 8-OHdG on admission and the severity and prognosis of hospitalized COPD patients with acute exacerbation.

METHODS

A total of 150 COPD hospitalized patients and 150 healthy individuals were recruited. Serum 8-OHdG was measured by ELISA and the length of hospital stay was calculated. The number of acute exacerbations of COPD was tracked within 1 year after this hospitalization.

RESULTS

The levels of serum 8-OHdG were elevated in COPD patients compared with the control group. Serum 8-OHdG was gradually elevated with decreased pulmonary function in COPD patients. Furthermore, Pearson linear association found that the levels of serum 8-OHdG were inversely correlated with pulmonary function and positively correlated with inflammatory cytokines in COPD patients. In addition, logistic regression analysis revealed that serum 8-OHdG elevation was a risk factor for pulmonary function decline in COPD patients. The length of hospital stay was tracked at this time. Higher serum 8-OHdG on admission increased the length of hospital stay among COPD patients.

CONCLUSION

Serum 8-OHdG on admission is positively correlated with the severity and adverse prognosis among COPD patients, suggesting that 8-OHdG may be involved in the pathogenesis of COPD. Serum 8-OHdG may be a biomarker to predict the progression of COPD.

Critical Roles of the Circadian Transcription Factor BMAL1 in Reproductive Endocrinology and Fertility

Brain and muscle aryl-hydrocarbon receptor nuclear translocator like protein1 (BMAL1), a core component of circadian oscillation, is involved in many physiological activities. Increasing evidence has demonstrated the essential role of BMAL1 in reproductive physiology. For instance, BMAL1-knockout (KO) mice were infertile, with impaired reproductive organs and gametes. Additionally, in BMAL1-KO mice, hormone secretion and signaling of hypothalamus-pituitary-gonadal (H-P-G) hormones were also disrupted, indicating that H-P-G axis was impaired in BMAL1-KO mice. Moreover, both BMAL1-KO mice and BMAL1-knockdown by small interfering RNA (siRNA) in vitro cultured steroidogenic cells showed that BMAL1 was associated with gonadal steroidogenesis and expression of related genes. Importantly, BMAL1 also participates in pathogenesis of human reproductive diseases. In this review, we elaborate on the impaired reproduction of BMAL1-KO mice including the reproductive organs, reproductive endocrine hormones, and reproductive processes, highlighting the vital role of BMAL1 in fertility and reproductive endocrinology.

Melatonin supplementation in the culture medium rescues impaired glucose metabolism in IVF mice offspring

Increasing evidence suggests that in vitro fertilization (IVF) may be associated with an increased risk of developing obesity and metabolic diseases later in life in the offspring. Notably, the addition of melatonin to culture medium may improve embryo development and prevent cardiovascular dysfunction in IVF adult mice. This study aimed to determine if melatonin supplementation in the culture medium can reverse impaired glucose metabolism in IVF mice offspring and the underlying mechanisms. Blastocysts used for transfer were generated by natural mating (control group) or IVF with or without melatonin (10^-6  M) supplementation (mIVF and IVF group, respectively) in clinical-grade culture media. Here, we first report that IVF decreased hepatic expression of Fbxl7, which was associated with impaired glucose metabolism in mice offspring. Melatonin addition reversed the phenotype by up-regulating the expression of hepatic Fbxl7. In vitro experiments showed that Fbxl7 enhanced the insulin signaling pathway by degrading RhoA through ubiquitination and was up-regulated by transcription factor Foxa2. Specific knockout of Fbxl7 in the liver of adult mice, through tail intravenous injection of recombinant adeno-associated virus, impaired glucose tolerance, while overexpression of hepatic Fbxl7 significantly improved glucose tolerance in adult IVF mice. Thus, the data suggest that Fbxl7 plays an important role in maintaining glucose metabolism of mice, and melatonin supplementation in the culture medium may rescue the long-term risk of metabolic diseases in IVF offspring.

β-Estradiol inhibits melatonin synthesis and melatonin receptor expression in sheep granulosa cells

Melatonin, an important regulator of mammalian reproduction, is mainly produced in the pineal gland, and granulosa cells (GCs), the main mammalian ovarian secretory cells, synthesize melatonin and express melatonin receptors (MRs) MT1 and MT2. However, studies on melatonin regulation in GCs are lacking in sheep. In this study, we explored the effects of β-estradiol (E2) on melatonin production and MR expression in GCs. We cultured sheep GCs to analyze the expression of the melatonin rate-limiting enzymes AANAT and HIOMT and the effects of E2 on AANAT, HIOMT, and MR expression and melatonin synthesis. To determine whether estrogen receptors (ERs) mediated E2 action on melatonin secretion and MR expression, we assessed ERA and ERB expression in GCs and observed whether ER antagonists counterbalanced the effects of E2. GCs expressed AANAT and HIOMT mRNA, indicating that they transformed exogenous serotonin into melatonin. E2 inhibited melatonin production by downregulating AANAT, HIOMT, and MRs. GCs expressed ERA and ERB; ERA/ERB inhibitors abolished E2-mediated inhibition of melatonin secretion and MR expression. PHTPP upregulated melatonin secretion and MT1 expression in E2-treated GCs, but did not significantly affect AANAT and MT2 expression. In conclusion, melatonin secretion in GCs was inhibited by E2 through an ERA- and ERB-mediated process.

Towards Personalized Antioxidant Use in Female Infertility: Need for More Molecular and Clinical Studies

Treatment with antioxidants is increasingly used to slow down aging processes in different organs of the human body, including those implicated in female fertility. There is a plethora of different natural, synthetic or semi-synthetic medicines available on the market; most of them can be purchased without medical prescription. Even though the use of antioxidants, even under conditions of auto-medication, was shown to improve many functions related to female infertility related to oxidative stress, the lack of medical control and supervision can lead to an overmedication resulting in an opposite extreme, reductive stress, which can be counterproductive with regard to reproductive function and produce various adverse health effects in general. This paper reviews the current knowledge relative to the effects of different antioxidants on female reproductive function. The persisting gaps in this knowledge are also highlighted, and the need for medical supervision and personalization of antioxidant prescription is underscored.

l-Argine regulates the proliferation, apoptosis and endocrine activity by alleviating oxidative stress in sheep endometrial epithelial cells

l-arginine (L-Arg) is a semiessential amino acid that plays crucial roles in the reproductive performance of animals. This research aimed to investigate the effect of supplementing L-Arg on endometrial epithelial cells (EECs) of Hu sheep. In vivo, female Hu sheep were randomly divided into three groups: control group (n = 5), nutrient-restricted group (n = 5), and L-Arg supplemented nutrient-restricted group (n = 5). Then, the effect of L-Arg on ovine endometrial growth and antioxidant capacity was assessed. We found that L-Arg supplementation promoted the growth of endometrial ductal gland invaginations (DGI), and alleviated oxidative stress in nutrient-restricted sheep. In order to investigate its mechanism, a H₂O₂-induced EECs oxidative stress model was established, and roles of L-Arg in EECs oxidation resistance, proliferation, apoptosis and endocrine activity were studied in vitro. Our results showed that L-Arg markedly decreased the release of reactive oxygen species (ROS) and malonaldehyde (MDA), and enhanced the expression and activity of certain antioxidant enzymes in EECs challenged by the H₂O₂ (p < 0.05). Supplementation of L-Arg significantly reduced the effect of 200 μM H₂O₂ on the viability of EECs (p < 0.05). In addition, EECs treated with L-Arg significantly alleviated the G0/G1-phase cell cycle arrest, apoptosis, and the inhibition of endometrial growth factors expression caused by H₂O₂ (p < 0.05). Overall, the results demonstrate that L-Arg performs crucial roles in maintaining the proliferation of ovine EECs, endocrine activity and inhibiting apoptosis through reducing oxidative stress. This study offers a theoretical basis for using L-Arg to improve sheep the uterine function.

MTNR1A gene polymorphisms and reproductive recovery after seasonal anoestrus in different Mediterranean sheep breeds

The aims of this study were 1) to investigate the effect of MTNR1A gene polymorphisms on reproductive performance in ewes of one Italian and two Slovenian dairy sheep breeds (Sarda, Istrian Premenka and Boska, respectively) which were located at different latitudes, and 2) to highlight if the different season of the male placement with females that was utilized in the different breeding systems in Sardinia (Italy) and Slovenia resulted in different effects of these polymorphisms on reproductive functions. Reproductively mature ewes (n = 100) from each breed were utilized to conduct the study. To evaluate the reproductive efficiency, lambing dates and number of lambs born were recorded per ewe; additionally, the duration in days from ram placement with ewes to lambing (DRPEL), litter size and the fertility rate were determined based on lambing dates. In each breed, there were eight nucleotide variations within the MTNR1A gene exon II, two of which (g.17355358 and g.17355171), respectively, resulted in a valine to isoleucine, and alanine to aspartic acid substitution, in amino acid sequence. The SNPs at position g.17355452 and g.17355458 were determined to have effects on reproductive performance. Genotypes C/C and C/T at g.17355452 in Bovska and Sarda and genotype A/A at g.17355458 in Istrian Pramenka were associated with a greater fertility and a lesser duration in days from ram placement with ewes to lambing. These findings confirmed that the nucleotide sequences of the MTNR1A gene could affect reproductive functions of Mediterranean sheep.

Protegrin-1 inhibits porcine ovarian granulosa cell apoptosis from H2O2-induced oxidative stress via the PERK/eIF2α/CHOP signaling pathway in vitro

In mammals, oxidative stress-induced apoptosis of granulosa cells is one of the major causes of follicular atresia, affecting ovarian physiological function. Protegrin-1 (PG-1) is an antimicrobial peptide with effective antimicrobial activity, immunomodulatory function, and porcine growth-promoting effects. PG-1 has been detected in porcine ovaries follicles. This study aimed to investigate the effect of PG-1 on oxidative stress-induced apoptosis of porcine ovarian granulosa cells and the underlying molecular mechanism. Granulosa cells were obtained from porcine follicles and treated with H₂O₂ to establish the oxidative stress model, and then treated with or without PG-1 (10 μg/mL). PG-1 significantly suppressed H₂O₂-induced apoptosis in granulosa cells after 24 h of treatment. Furthermore, these results revealed that PG-1 increased the mRNA and protein expression of anti-apoptotic B cell lymphoma/leukemia 2 (BCL2) and the BCL2/Bcl-2-associated X protein (BAX) ratio while decreasing the expression of pro-apoptotic BAX and active caspase-3. Using Western blot analysis, it was found that PG-1 decreased the phosphorylation of RNA-like endoplasmic reticulum kinase (PERK) and the α-subunit of eukaryotic initiation factor 2 (eIF2α) as well as the protein expression level of CCAAT enhancer-binding protein homologous protein (CHOP), all of which were increased by H₂O₂. Moreover, inhibitors against PERK and phospho-eIF2ɑ both suppressed the H₂O₂-induced granulosa cells apoptosis and enhanced the anti-apoptosis effect of PG-1. Taken together, our findings demonstrated that PG-1 inhibited porcine ovarian granulosa cell apoptosis from oxidative stress via the PERK/eIF2α/CHOP signaling pathway in vitro, which suggests the novel regulatory function of the antimicrobial peptide in the ovary.

Understanding the cross-talk between mediators of infertility and COVID-19

COVID-19 is the ongoing health emergency affecting individuals of all ages around the globe. Initially, the infection was reported to affect pulmonary structures. However, recent studies have delineated the impacts of COVID-19 on the reproductive system of both men and women. Hence, the present review aims to shed light on the distribution of SARS-CoV-2 entry factors in various reproductive organs. In addition, impacts of COVID-19 mediators like disrupted renin angiotensin system, oxidative stress, cytokine storm, fever, and the mental stress on reproductive physiology have also been discussed. For the present study, various keywords were used to search literature on PubMed, ScienceDirect, and Google Scholar databases. Articles were screened for relevancy and were studied in detail for qualitative synthesis of the review. Through our literature review, we found a multitude of effects of COVID-19 mediators on reproductive systems. Studies reported expression of receptors like ACE-2, TMPRSS2, and CD147 in the testes, epididymis, prostrate, seminal vesicles, and ovarian follicles. These proteins are known to serve as major SARS-CoV-2 entry factors. The expression of lysosomal cathepsins (CTSB/CTSL) and/ neuropilin-1 (NRP-1) are also evident in the testes, epididymis, seminal vesicles, fallopian tube, cervix, and endometrium. The binding of viral spike protein with ACE-2 was found to alter the renin-angiotensin cascade, which could invite additional infertility problems. Furthermore, COVID-19 mediated cytokine storm, oxidative stress, and elevated body temperature could be detrimental to gametogenesis, steroidogenesis, and reproductive cycles in patients. Finally, social isolation, confinement, and job insecurities have fueled mental stress and frustration that might promote glucocorticoid-mediated subnormal sperm quality in men and higher risk of miscarriage in women. Hence, the influence of COVID-19 on the alteration of reproductive health and fertility is quite apparent.

Oral melatonin supplementation during in vitro fertilization treatment: a systematic PRISMA review and meta-analysis of randomized controlled trials

OBJECTIVE

High levels of reactive oxygen species (ROS) have been suspected of reducing the success rate of assisted reproductive technology (ART). Melatonin has anti-oxidative properties and could therefore be of interest as a supplement in in vitro-fertilization (IVF) protocols. The objective of this study was to evaluate if a melatonin supplementation given in vivo to women undergoing IVF-treatment can improve the outcome.

METHODS

A systematic literature search was performed on PubMed, Embase and Cochrane. The methodological quality of the included studies was assessed using the version 2 of the Cochrane risk-of-bias tool (RoB2). Primary outcome was clinical pregnancy rate (CPR). Secondary outcomes were total number of oocytes, number of mature oocytes, embryo quality, biochemical pregnancy rate, miscarriage rate and live birth rate (LBR).

RESULTS

Seven randomized controlled trials (RCT) were included. The meta-analysis demonstrated a significantly higher mature oocyte count when melatonin was used (Mean Diff. = 1,82; 95% CI 0.37-3.27; p = .01). All seven studies showed a trend for increase in CPR, although not significant. No other measured outcomes showed a significant improvement. Two studies had 'low risk', three 'some concerns' and two studies had 'high risk' of bias.

CONCLUSION

This meta-analysis including RCT indicates that an oral melatonin supplement during IVF-treatment can increase the number of mature oocytes, and a trend for increase CPR, albeit not significant. Most of the included studies were small. The methodological quality in three of the seven studies was moderate and two were low. Further investigations are needed to support the positive findings.

Effects of melatonin and human follicular fluid supplementation of in vitro maturation medium on mouse vitrified germinal vesicle oocytes: A laboratory study

Background

Vitrification as the most efficient method of cryopreservation, enables successful storage of oocytes for couples who undergo specific procedures including surgery and chemotherapy. However, the efficacy of in vitro maturation (IVM) methods with vitrified germinal vesicle (GV) oocytes could be improved.

Objective

As melatonin and follicular fluid (FF) might enhance IVM conditions, we used these supplements to assess the maturation rate of vitrified GV oocytes and their artificial fertilization rate.

Materials and Methods

Four hundred mouse GV oocytes were harvested, vitrified, and assigned into control (C-Vit-GV) and treatment groups of melatonin (M-Vit-GV), human follicular fluid (HFF-Vit-GV), and a combination (M + HFF-Vit-GV). A non-vitrified group of GV oocytes (non-Vit-GV) and a group of in vivo matured metaphase II (Vivo-MII) oocytes served as control groups to evaluate the vitrification and IVM conditions, respectively. Maturation of GV oocytes to MII and further development to two-cell-stage embryos were determined in the different groups.

Results

Development to two-cell embryos was comparable between the Vivo-MII and non-Vit-GV groups. IVM and in vitro fertilization (IVF) results in the non-Vit-GV group were also comparable with the C-Vit-GV oocytes. In addition, the IVM and IVF outcomes were similar across the different treatment groups including the M-Vit-GV, HFF-Vit-GV, M + HFF-Vit-GV, and C-Vit-GV oocytes.

Conclusion

Employing an appropriate technique of vitrification followed by suitable IVM conditions can lead to reasonable IVF outcomes which may not benefit from extra supplementations. However, whether utilizing other supplementation formulas could improve the outcome requires further investigation.

Melatonin and Pathological Cell Interactions: Mitochondrial Glucose Processing in Cancer Cells

Melatonin is synthesized in the pineal gland at night. Since melatonin is produced in the mitochondria of all other cells in a non-circadian manner, the amount synthesized by the pineal gland is less than 5% of the total. Melatonin produced in mitochondria influences glucose metabolism in all cells. Many pathological cells adopt aerobic glycolysis (Warburg effect) in which pyruvate is excluded from the mitochondria and remains in the cytosol where it is metabolized to lactate. The entrance of pyruvate into the mitochondria of healthy cells allows it to be irreversibly decarboxylated by pyruvate dehydrogenase (PDH) to acetyl coenzyme A (acetyl-CoA). The exclusion of pyruvate from the mitochondria in pathological cells prevents the generation of acetyl-CoA from pyruvate. This is relevant to mitochondrial melatonin production, as acetyl-CoA is a required co-substrate/co-factor for melatonin synthesis. When PDH is inhibited during aerobic glycolysis or during intracellular hypoxia, the deficiency of acetyl-CoA likely prevents mitochondrial melatonin synthesis. When cells experiencing aerobic glycolysis or hypoxia with a diminished level of acetyl-CoA are supplemented with melatonin or receive it from another endogenous source (pineal-derived), pathological cells convert to a more normal phenotype and support the transport of pyruvate into the mitochondria, thereby re-establishing a healthier mitochondrial metabolic physiology.

Review: What have we learned about the effects of heat stress on the pig industry?

Pig production faces seasonal fluctuations. The low farrowing rate of sows mated in summer, increased carcass fatness of progeny born to the sows mated in summer, and slower growth rate of finisher pigs in summer are three economically important impacts identified in the pig industry. The purpose of this review is to examine advances over the past decade in understanding the mechanisms underlying the three impacts associated with summer conditions, particularly heat stress (HS), and to provide possible amelioration strategies. For impact 1, summer mating results in low farrowing rates mainly caused by the high frequency of early pregnancy disruptions. The contributions of semen DNA damage, poor oocyte quality, local progesterone concentrations, and suboptimal embryonic oestrogen secretion are discussed, as these all may contribute to HS-mediated effects around conception. Despite this, it is still unclear what the underlying mechanisms might be and thus, there is currently a lack of commercially viable solutions. For impact 2, there have been recent advances in the understanding of gestational HS on both the sow and foetus, with gestational HS implicated in decreased foetal muscle fibre number, a greater proportion of lighter piglets, and increased carcass fatness at slaughter. So far, no effective strategies have been developed to mitigate the impacts associated with gestational HS on foetuses. For impact 3, the slowed growth rate of pigs during summer is one reason for the reduced carcass weights in summer. Studies have shown that the reduction in growth rates may be due to more than reductions in feed intake alone, and the impaired intestinal barrier function and inflammatory response may also play a role. In addition, it is consistently reported that HS attenuates fat mobilisation which can potentially exacerbate carcass fatness when carcass weight is increased. Novel feed additives have exhibited the potential to reduce the impacts of HS on intestinal barrier function in grower pigs. Collectively, based on these three impacts, the economic loss associated with HS can be estimated. A review of these impacts is warranted to better align the future research directions with the needs of the pig industry. Ultimately, a better understanding of the underlying mechanisms and continuous investments in developing commercially viable strategies to combat HS will benefit the pig industry.

Impact of the antioxidant quercetin on morphological integrity and follicular development in the in vitro culture of Bos indicus female ovarian fragments

We evaluated the effect of quercetin on the in vitro culture of bovine ovarian fragments in relation to morphology, development, and oxidative stress. Ovaries (n = 12) from Nelore heifers (n = 6) were used. Each pair of ovaries was divided into nine fragments, and one fragment from each animal was fixed in Bouin solution for 24 h (histology control) or frozen (- 80°C; control for oxidative stress). Other ovarian fragments (n = 8) were distributed into concentrations of 0, 10, 25, and 50 μg/mL of quercetin added to the culture medium for 5 or 10 d. Data were analyzed by chi-square test or ANOVA followed by Tukey's test (P < 0.05). Treatment with 25 μg/mL quercetin resulted in the highest proportion of total intact follicles for 5 (67.3%) and 10 d (57.1%); the concentration of 25 μg/mL also presented the best proportion of developing follicles for 5 d (68.7%) and 10 d (62.8%). Treatment with 25 μg/mL quercetin resulted in significant ferric reduction for 10 d of culture, but not for 5 d. No difference (P > 0.1) was observed in the production of reactive oxygen species or in the oxidative degradation of lipids between treatments and non-cultivated controls. Treatment with 25 μg/mL quercetin preserved the morphological integrity of the developing follicles for 5 and 10 d of culture, in addition to promoting the best antioxidant potential after 10 d of culture in bovine ovarian fragments.

Molecular Evidence of the Inhibitory Potential of Melatonin against NaAsO2-Induced Aging in Male Rats

Arsenic (As) poisoning is widespread due to exposure to pollution. The toxic level of (As) causes oxidative stress-induced aging and tissue damage. Since melatonin (MLT) has anti-oxidant and anti-aging properties, we aimed to evaluate the protective effect of MLT against the toxicity of sodium arsenite (NaAsO₂). Healthy male NMRI mice were divided into eight different groups. The control group received a standard regular diet. Other groups were treated with varying diets, including MLT alone, NaAsO₂, and NaAsO₂ plus MLT. After one month of treatment, biochemical and pathological tests were performed on blood, heart, and lung tissue samples. NaAsO₂ increased the levels of TNF-α, 8-hydroxy-2-deoxy guanosine (8OHdG), malondialdehyde (MDA), reactive oxygen species (ROS), and high mobility group box 1 (HMGB1), increased the expression of TNF receptor type 1-associated death domain (TRADD) mRNA and telomerase reverse transcriptase, and decreased the expression of Klotho (KL) mRNA in both plasma and tissues. In contrast, MLT reduced MDA, ROS, HMGB1, lactate, and TNF-α enhanced the mRNA expression of KL, and suppressed the mRNA expression of the TERT and TRADD genes. Thus, MLT confers potent protection against NaAsO₂- induced tissue injury and oxidative stress.

Redox Regulation and Oxidative Stress in Mammalian Oocytes and Embryos Developed In Vivo and In Vitro

Oocytes and preimplantation embryos require careful regulation of the redox environment for optimal development both in vivo and in vitro. Reactive oxygen species (ROS) are generated throughout development as a result of cellular metabolism and enzyme reactions. ROS production can result in (i) oxidative eustress, where ROS are helpful signalling molecules with beneficial physiological functions and where the redox state of the cell is maintained within homeostatic range by a closely coupled system of antioxidants and antioxidant enzymes, or (ii) oxidative distress, where excess ROS are deleterious and impair normal cellular function. in vitro culture of embryos exacerbates ROS production due to a range of issues including culture-medium composition and laboratory culture conditions. This increase in ROS can be detrimental not only to assisted reproductive success rates but can also result in epigenetic and genetic changes in the embryo, resulting in transgenerational effects. This review examines the effects of oxidative stress in the oocyte and preimplantation embryo in both the in vivo and in vitro environment, identifies mechanisms responsible for oxidative stress in the oocyte/embryo in culture and approaches to reduce these problems, and briefly examines the potential impacts on future generations.

Mitochondria-related changes and metabolic dysfunction in low prognosis patients under the POSEIDON classification

STUDY QUESTION

What is the relationship between mitochondria of granulosa cells (GCs) and age and ovarian function in the patients under the POSEIDON classification?

SUMMARY ANSWER

Our results revealed obvious abnormal mitochondrial-related changes in low prognosis IVF population, where age and the function of ovarian reserve exerted a divergent effect on mitochondrial content and function.

WHAT IS KNOWN ALREADY

Mitochondria have an important role in the cross-talk between GCs and oocytes. However, factors affecting mitochondria of GCs and related mechanisms are still poorly understood.

STUDY DESIGN, SIZE, DURATION

GCs samples were obtained from 119 infertile women undergoing IVF from September 2020 to February 2021. Six groups were investigated by the POSEIDON stratification: young with normal prognosis (C1), aging with normal prognosis (C2), young and low prognosis group with normal ovarian reserve (NOR) (G1), aging and low prognosis group with NOR (G2), young and low prognosis group with diminished ovarian reserve (DOR) (G3), and aging and low prognosis group with DOR (G4).

PARTICIPANTS/MATERIALS, SETTING, METHODS

The morphology of GC mitochondria was observed by transmission electron microscopy. MtDNA copy number and mitochondrial replication-related genes were detected by real-time quantitative PCR (qPCR). Mitochondrial membrane potential (MMP) and cytosolic reactive oxygen species (ROS) were detected by confocal microscopy. Cellular glycolysis and aerobic respiratory capacity were analyzed by Seahorse XFe96 Analyzer, and related gene expression and protein levels were assessed by qPCR and Western blot.

MAIN RESULTS AND THE ROLE OF CHANCE

Compared to the normal prognosis groups, mitochondrial morphology was impaired in the low prognosis groups, where the young groups (G1, G3) with low prognosis showed phenotypes undergoing oxidative stress (round, vacuolated, swollen with decreased matrix density) and the aging groups (G2, G4) revealed typical aging characteristics (an irregular shape with heterogeneous matrix density and cord-like cristae). Additionally, the degree of corresponding change and damage was more obvious in patients with DOR (G3, G4) regardless of age. For mitochondrial content, the mtDNA copy number in GCs was significantly negatively correlated with age in the low prognosis groups (β = -0.373, P = 0.005). Interestingly, the relationship between mtDNA copy number and anti-Mullerian hormone score differed between the two age groups with low prognosis, with a negative correlation in the young groups (β = -0.639, P = 0.049) and a positive correlation in the aging groups (β = 0.505, P = 0.039). In addition, significantly reduced mitochondrial activity (MMP, ROS) and cell metabolism (both glycolysis and OXPHOS) were observed in the low prognosis groups, with the most obvious decrease being observed in the DOR population. However, the metabolism of the GCs in normal prognosis aging women (C2) shifted from OXPHOS to anaerobic glycolysis.

LIMITATIONS, REASONS FOR CAUTION

Owing to the difficulties involved in primary GC collection and culture, the sample size was limited.

WIDER IMPLICATIONS OF THE FINDINGS

Mitochondrial abnormality is closely linked to the low prognostic outcome in IVF patients. Supplementing the functional mitochondrial content or improving mitochondrial function by autologous mitochondrial transfer or mitochondrial-related regulating drugs may help improve the clinical outcomes in patients with a low prognosis, especially for those with DOR.

STUDY FUNDING/COMPETING INTEREST(S)

This work was supported by the National Natural Science Foundation of China (No. 21737001), the Peking University Clinical Medicine + X Youth Project (PKU2020LCXQ011), the Research and Development Program of Peking University People's Hospital (No. RDH2017-03; No. RDX2019-06) and the Application of Clinical Features of Capital Special Subject (Z171100001017130). There were no competing interests.

TRIAL REGISTRATION NUMBER

This study was registered with the Chinese Clinical Trial Register (Clinical Trial Number: ChiCTR2100045531).

Roles of melatonin in the field of reproductive medicine

Melatonin, mostly released by the pineal gland, is a circadian rhythm-regulated and multifunctional hormone. Great advances in melatonin research have been made, including its role in rhythms of the sleep-wake cycle, retardation of ageing processes, as well as antioxidant or anti-inflammatory functions. Melatonin can scavenge free radicals such as reactive oxygen species (ROS), a key factor in reproductive functions. Melatonin plays an important role in oocyte maturation, fertilization and embryonic development as well. The concurrent use of melatonin increases the number of mature oocytes, the fertilization rate, and number of high-quality embryos, which improves the clinical outcome of assisted reproductive technology (ART). This review discusses the relationship between melatonin and human reproductive function, and potential clinical applications of melatonin in the field of reproductive medicine.