The role of melatonin as an antioxidant in the follicle

Melatonin and resveratrol alleviate molecular and metabolic toxicity induced by Bisphenol A in endometrial organoids

Bisphenol A (BPA), a widespread environmental contaminant, poses concerns due to its disruptive effects on physiological functions of the uterine endometrium. In contrast, melatonin (MT) and Resveratrol (RSV) are under scrutiny for their potential protective roles against BPA-induced damage. For the efficacy and ethical concerns in the animal test, endometrial organoids, three-dimensional models mimicking endometrium, serve as crucial tools for unraveling the impact of environmental factors on reproductive health. This study aimed to comprehensively characterize the morphological, molecular and metabolic responses of porcine endometrial organoids to BPA and assess the potential protective effects of MT and RSV. Porcine uteri were prepared, digested with collagenase, mixed with Matrigel, and incubated at 38°C with 5 % CO2. Passaging involved dissociation through trypsin-EDTA treatment and subculturing. The culture medium was refreshed every 2-3 days. To investigate the environmental impact on reproductive health, endometrial organoids were treated with BPA (0.5 µM), MT (with/without BPA at 0.1 µM), and/or RSV (10 µM). Various molecular screening using gene expression, western blotting, immunofluorescence staining, and metabolites profiling were assessed the effects of BPA, MT, and RSV in terms of cell viability, morphology, reproductivity, and metabolism alteration in the endometrial organoids. As expected, BPA induced structural and molecular disruptions in organoids, affecting cytoskeletal proteins, Wnt/β-catenin signaling, and epithelial/mesenchymal markers. It triggered oxidative stress and apoptotic pathways, altered miRNA expression, and disrupted the endocannabinoid system. The level of glucose, galactose, and essential amino acids were increased or decreased by approximately 1.5-3 times in BPA-treated groups compared to the control groups (p-value < 0.05), indicating metabolic changes. Moreover, MT and RSV treated groups exhibited protective effects, mitigating BPA-induced disruptions across multiple pathways. For the first time, our study models endometrial organoids, advancing understanding of environmental impacts on reproductive health.

Effects of acute hypothyroidism on plasma melatonin and Aanat and Asmt expression in the pineal gland and gonads of rats

Introduction

The reproductive system is tightly regulated by environmental and physiological signals. Melatonin, known as the hormone of darkness, plays a crucial role in regulating both the circadian and reproductive systems in mammals. Hypothyroidism is a key endocrine disorder that harms the reproductive system. Despite many studies on melatonin's effects on the reproductive system, there is conflicting information regarding melatonin synthesis modulation in hypothyroidism. The objective of this study was to investigate the modulation of plasma melatonin levels and gene expression of Aanat and Asmt in the pineal gland and gonads of rats with hypothyroidism at different times of the day.

Methods

Female and male Wistar rats were divided into control and hypothyroid groups. Hypothyroidism was induced using propylthiouracil (PTU) for 15 days, rats were euthanized six hours after lights on (ZT6), before lights off (ZT11.5), and six hours after lights off (ZT18). Free thyroxine (FT4) and melatonin were quantified in plasma, and gene expressions of melatonin synthesizing enzymes (Aanat and Asmt) were measured in pineal and sexual organs (testis and ovary). Also, morphological analysis was performed in sexual organs.

Results

The results reveal some disparities between the sexes. Hypothyroidism reduced antral and primary follicles in the ovary, and reduced the weight of testis, epididymis, and prostate. In relation to gene expression, we observed a reduction in Aanat expression in the pineal gland during the light phase (ZT6), and in males, this reduction occurred during the dark phase (ZT18). Regarding Asmt expression, there was a decrease in females also during the dark phase (ZT18). In the gonads, there was an increase in expression in both sexes at ZT11.5. Additionally, it was interesting to observe the association between FT4 levels and Asmt expression in the gonads.

Conclusions

This study showed that acute hypothyroidism can affect components of the melatonergic system in gonads, particularly gene expression of melatonin synthesis enzymes (Aanat and Asmt) contributing to changes in reproduction organs during disease progression. These findings enhance our understanding of melatonin synthesis in the reproductive system during hypothyroidism, showing distinct responses in male and female rats, and suggest that hypothyroidism affects the circadian rhythmicity of melatonin synthesis in a sex-dependent manner.

Effect on serum metabolomics of rats with premature ovarian insufficiency by Zhibian (BL54) through Shuidao (ST28) acupuncture

OBJECTIVE

To analyze the serum metabolic targets of the "Zhibian (BL54) through Shuidao (ST28)" acupuncture technique in cyclophosphamide (CTX)-induced premature ovarian insufficiency (POI) model rats and to elucidate the potential molecular mechanism of acupuncture in improving POI.

METHODS

We used an intraperitoneal injection of CTX to establish the POI rat model (POI group) and compared serum hormone levels and ovarian histopathological changes to evaluate the effect of the Zhibian (BL54) through Shuidao (ST28) technique (ZS + POI group) on ovarian function. Then, nontargeted metabolomics was performed using rat serum by ultra-performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF/MS).

RESULTS

After acupuncture intervention, the serum hormone levels and ovarian pathological morphology of POI rats were effectively improved. Moreover, UPLC-Q-TOF/MS results showed that the ZS + POI group showed a significant reversal of the levels of 6 differential metabolites. Among them, the levels of four serum metabolic markers, divanillyltetrahydrofuran ferulate, trans-ferulic acid, tryptamine, and neuraminic acid, increased significantly. Further analysis of biological effects showed that all metabolites were involved in the regulation of reproductive hormone levels and antioxidant and antiapoptotic effects.

CONCLUSIONS

The "Zhibian (BL54) through Shuidao (ST28)" acupuncture method may improve the ovarian function of POI rats by regulating serum metabolite markers to exert antioxidant and antiapoptotic effects, which provides a theoretical basis for the clinical application of acupuncture in the treatment of POI.

Ovarian overexpression of ASMT gene increases follicle numbers in transgenic sheep: Association with lipid metabolism

Melatonin plays an important role in mammalian reproductive activities, to further understand the effects of endogenous melatonin on functions of ovary, the transgenic sheep with overexpression of melatonin synthetic enzyme gene ASMT in ovary were generated. The results showed that total melatonin content in follicular fluid of transgenic sheep was significantly greater than that in the wild type. Accordingly, the follicle numbers of transgenic sheep were also significantly greater than those in the WT. The results of follicular fluid metabolites sequencing showed that compared with WT, the differential metabolites of the transgenic sheep were significantly enriched in several signaling pathways, the largest number of metabolites was lipid metabolism pathway and the main differential metabolites were lipids and lipoid molecules. SMART-seq2 were used to analyze the oocytes and granulosa cells of transgenic sheep and WT sheep. The main differential enrichment pathway was metabolic pathway, in which lipid metabolism genes accounted for the majority. In conclusion, this is the first report to show that ovary overexpression of ASMT increased local melatonin production and follicle numbers. These results may imply that ASMT plays an important role in follicle development and formation, and melatonin intervention may be a potential method to promote this process.

Zinc improves the developmental ability of bovine in vitro fertilization embryos through its antioxidative action

Zinc, an essential trace mineral, exerts a pivotal influence in various biological processes. Through zinc concentration analysis, we found that the zinc concentration in the bovine embryo in vitro culture (IVC) medium was significantly lower than that in bovine follicular fluid. Therefore, this study explored the impact of zinc sulfate on IVC bovine embryo development and investigated the underlying mechanism. The results revealed a significant decline in zygote cleavage and blastocyst development rates when zinc deficiency was induced using zinc chelator N, N, N', N'-Tetrakis (2-pyridylmethyl) ethylenediamine (TPEN) in culture medium during embryo in vitro culture. The influence of zinc-deficiency was time-dependent. Conversely, supplementing 0.8 μg/mL zinc sulfate to culture medium (CM) increased the cleavage and blastocyst formation rate significantly. Moreover, this supplementation reduced reactive oxygen species (ROS) levels, elevated the glutathione (GSH) levels in blastocysts, upregulated the mRNA expression of antioxidase-related genes, and activated the Nrf2-Keap1-ARE signaling pathways. Furthermore, 0.8 μg/mL zinc sulfate enhanced mitochondrial membrane potential, maintained DNA stability, and enhanced the quality of bovine (in vitro fertilization) IVF blastocysts. In conclusion, the addition of 0.8 μg/mL zinc sulfate to CM could enhance the antioxidant capacity, activates the Nrf2-Keap1-ARE signaling pathways, augment mitochondrial membrane potential, and stabilizes DNA, ultimately improving blastocyst quality and in vitro bovine embryo development.

Melatonin: Current evidence on protective and therapeutic roles in gynecological diseases

Melatonin, a potent antioxidant and free radical scavenger, has been demonstrated to be effective in gynecological conditions and female reproductive cancers. This review consolidates the accumulating evidence on melatonin's multifaceted protective effects in different pathological contexts. In gynecological conditions such as endometriosis, polycystic ovary syndrome (PCOS), and uterine leiomyoma, melatonin has shown promising effects in reducing oxidative stress, inflammation, and hormonal imbalances. It inhibits adhesion molecules' production, and potentially mitigates leukocyte adherence and inflammatory responses. Melatonin's regulatory effects on hormone production and insulin sensitivity in PCOS individuals make it a promising candidate for improving oocyte quality and menstrual irregularities. Moreover, melatonin exhibits significant antitumor effects by modulating various signaling pathways, promoting apoptosis, and suppressing metastasis in breast cancers and gynecological cancers, including ovarian, endometrial, and cervical cancers. Furthermore, melatonin's protective effects are suggested to be mediated by interactions with its receptors, estrogen receptors and other nuclear receptors. The regulation of clock-related genes and circadian clock systems may also contribute to its inhibitory effects on cancer cell growth. However, more comprehensive research is warranted to fully elucidate the underlying molecular mechanisms and establish melatonin as a potential therapeutic agent for these conditions.

Exploring melatonin's multifaceted role in female reproductive health: From follicular development to lactation and its therapeutic potential in obstetric syndromes

BACKGROUND

Melatonin is mainly secreted by the pineal gland during darkness and regulates biological rhythms through its receptors in the suprachiasmatic nucleus of the hypothalamus. In addition, it also plays a role in the reproductive system by affecting the function of the hypothalamic-pituitary-gonadal axis, and by acting as a free radical scavenger thus contributing to the maintenance of the optimal physiological state of the gonads. Besides, melatonin can freely cross the placenta to influence fetal development. However, there is still a lack of overall understanding of the role of melatonin in the reproductive cycle of female mammals.

AIM OF REVIEW

Here we focus the role of melatonin in female reproduction from follicular development to delivery as well as the relationship between melatonin and lactation. We further summarize the potential role of melatonin in the treatment of preeclampsia, polycystic ovary syndrome, endometriosis, and ovarian aging.

KEY SCIENTIFIC CONCEPTS OF REVIEW

Understanding the physiological role of melatonin in female reproductive processes will contribute to the advancement of human fertility and reproductive medicine research.

Revealing Changes in Ovarian and Hemolymphatic Metabolites Using Widely Targeted Metabolomics between Newly Emerged and Laying Queens of Honeybee (Apis mellifera)

The queen bee is a central and pivotal figure within the colony, serving as the sole fertile female responsible for its reproduction. The queen possesses an open circulatory system, with her ovaries immersed in hemolymph. A continuous and intricate transportation and interchange of substances exist between the ovaries and hemolymph of queen bees. To determine the characteristic metabolites in the hemolymph and ovary, as well as understand how their rapid metabolism contributes to the process of egg-laying by queens, we reared Apis mellifera queens from three different age groups: newly emerged queen (NEQ), newly laying queen (NLQ), and old laying queen (OLQ). Using widely targeted metabolomics, our study revealed that the laying queen (NLQ and OLQ) exhibited faster fatty acid metabolism, up-regulated expression of antioxidants, and significant depletion of amino acids compared to the NEQ. This study revealed that the levels of carnitine and antioxidants (GSH, 2-O-α-D-glucopyranosyl-L-ascorbic acid, L-ascorbic acid 2-phosphate, etc.) in the NLQ and OLQ were significantly higher compared to NEQ. However, most of the differentially expressed amino acids, such as L-tryptophan, L-tyrosine, L-aspartic acid, etc., detected in NLQ and OLQ were down-regulated compared to the NEQ. Following egg-laying, pathways in the queens change significantly, e.g., Tryptophan metabolism, Tyrosine metabolism, cAMP signaling pathway, etc. Our results suggest that carnitine and antioxidants work together to maintain the redox balance of the queen. Additionally, various amino acids are responsible for maintaining the queen's egg production.

Melatonin alleviates the toxic effect of di(2-ethylhexyl) phthalate on oocyte quality resulting from CEBPB suppression during primordial follicle formation

Presently, the exposure of plasticizers to humans and animals occurs daily, which pose a potential threat to reproductive health. In the present study, a pregnant mouse model exposed to di(2-ethylhexyl) phthalate (DEHP, one of the most common plasticizers) and melatonin was established, and the single-cell transcriptome technology was applied to investigate the effects of melatonin in ovarian cells against DEHP. Results showed that DEHP markedly altered the gene expression pattern of ovarian cells, and severely weakened the histone methylation modification of oocytes. The administration of melatonin recovered the expression of LHX8 and SOHLH1 proteins that essential for primordial follicle formation, and increased the expression of CEBPB, as well as key genes of histone methylation modification (such as Smyd3 and Kdm5a). In addition, the ovarian damage caused by DEHP was also relieved after the overexpression of CEBPB, which suggested melatonin could improve primordial follicle formation progress via enhancing CEBPB expression in mice. Besides, the apoptosis of ovarian cells induced by DEHP also was diminished by melatonin. The study provides evidence of melatonin preventing the damage mediated by plasticizers on the reproductive system in females and CEBPB may serve as a downstream target factor of melatonin in the process.

Exploring the impact of heat stress on oocyte maturation and embryo development in dairy cattle using a culture medium supplemented with vitamins E, C, and coenzyme Q10

Heat stress is a significant factor affecting the fertility of dairy cattle due to the generation of free radicals. In assisted reproductive techniques, the inclusion of protective antioxidants becomes crucial to mitigate potential cellular damage. This study aimed to explore the impact of supplementing vitamins E, C, and coenzyme Q10 into the oocyte culture medium, with the goal of ameliorating the adverse effects of heat stress on oocyte maturation and embryo development in dairy cattle. A group of fifty Holstein dairy cows were synchronized, and their oocytes were harvested using the ovum pick-up method. High-quality oocytes were subjected to in vitro maturation (IVM) and in vitro fertilization (IVF) procedures, utilizing a culture medium containing, no supplements (Group 1), 100 μM of vitamins E (Group 2) and C (Group 3), along with 50 μM of coenzyme Q10 (Group 4). The ensuing zygotes were cultured, and the ensuing embryos were evaluated for blastocyst formation by the seventh day. An analysis of the blastocysts' inner cell mass (ICM) and trophectoderm (TE) cells was also conducted. The findings revealed that the group receiving supplementation of vitamin E and coenzyme Q10 exhibited significantly higher maturation and cleavage rates in comparison to both the control and the vitamin C groups. Furthermore, the count of ICM, TE, and blastocyst cells was notably elevated in the vitamin E supplemented group when compared to the control group. In summary, the effectiveness of vitamin E in enhancing IVM, IVF, and embryo development under conditions of heat stress surpassed that of vitamin C and coenzyme Q10.

The Role of Melatonin to Ameliorate Oxidative Stress in Sperm Cells

It is widely accepted that oxidative stress (OS) coming from a wide variety of causes has detrimental effects on male fertility. Antioxidants could have a significant role in the treatment of male infertility, and the current systematic review on the role of melatonin to ameliorate OS clearly shows that improvement of semen parameters follows melatonin supplementation. Although melatonin has considerable promise, further studies are needed to clarify its ability to preserve or restore semen quality under stress conditions in varied species. The present review examines the actions of melatonin via receptor subtypes and its function in the context of OS across male vertebrates.

The Boosting Effects of Melatonin on the In Vitro Fertilization (IVF) of Women with Polycystic Ovary Syndrome

Polycystic ovary syndrome (PCOS) is one of the most critical disorders, which affects approximately 20% of women of childbearing age and melatonin supplementation in these women can be effective. However, human studies in this area are particularly limited to IVF candidates. The aim of this clinical trial study was to evaluate the effect of melatonin on the in vitro fertilization (IVF) in PCOS involved women. In this clinical trial study, a total of 320 women with PCOS were randomly assigned to the intervention and control groups. Patients in the intervention group (n=160) received a combination of melatonin and metformin (3 mg and 500 mg, respectively) three times a day. The control group (n=160) received metformin 500 mg from the luteal phase of the cycle before the start of gonadotropin. Oocyte and embryo quality, number of oocytes, and pregnancy outcomes were compared in both groups. Our study revealed that the frequency of Metaphase II oocytes (69.9% vs. 57.9%, p<0.001) and the number of embryos of the top-quality (grade A) were higher in the group treated with melatonin (40.3% vs. 29.9%, p=0.001). The rate of clinical pregnancy and implantation were also higher in the intervention group. The odds of clinical pregnancy in the intervention group was 1.8 times (p=0.039). Moreover, oral melatonin supplementation was effective in patients with PCOS, who were candidates for IVF because of the increased quality of mature oocytes, top-quality embryos, and increased odds of clinical pregnancy.

Investigation of SNP markers for the melatonin production trait in the Hu sheep with bulked segregant analysis

BACKGROUND

As an important reproductive hormone, melatonin plays an important role in regulating the reproductive activities of sheep and other mammals. Hu sheep is a breed favoring for meat, with prolific traits. In order to explore the relationship between melatonin and reproductive function of Hu sheep, 7,694,759 SNPs were screened out through the whole genome sequencing analysis from high and low melatonin production Hu sheep.

RESULTS

A total of 68,673 SNPs, involving in 1126 genes, were identified by ED association analysis. Correlation analysis of SNPs of AANAT/ASMT gene and MTNR1A/MTNR1B gene were carried out. The melatonin level of CG genotype 7,981,372 of AANAT, GA genotype 7,981,866 of ASMT and GG genotype 17,355,171 of MTNR1A were higher than the average melatonin level of 1.64 ng/mL. High melatonin Hu sheep appear to have better multiple reproductive performance.

CONCLUSIONS

By using different methods, three SNPs which are associated with high melatonin production trait have been identified in Hu sheep. These 3 SNPs are located in melatonin synthetase AANAT/ASMT and receptor MTNR1A, respectively. Considering the positive association between melatonin production and reproductive performance in ruminants, these three SNPs can be served as the potential molecular markers for breading Hu sheep with the desirable reproductive traits.

Creating a semi-opened micro-cavity ovary through sacrificial microspheres as an in vitro model for discovering the potential effect of ovarian toxic agents

The bio-engineered ovary is an essential technology for treating female infertility. Especially the development of relevant in vitro models could be a critical step in a drug study. Herein, we develop a semi-opened culturing system (SOCS) strategy that maintains a 3D structure of follicles during the culture. Based on the SOCS, we further developed micro-cavity ovary (MCO) with mouse follicles by the microsphere-templated technique, where sacrificial gelatin microspheres were mixed with photo-crosslinkable gelatin methacryloyl (GelMA) to engineer a micro-cavity niche for follicle growth. The semi-opened MCO could support the follicle growing to the antral stage, secreting hormones, and ovulating cumulus-oocyte complex out of the MCO without extra manipulation. The MCO-ovulated oocyte exhibits a highly similar transcriptome to the in vivo counterpart (correlation of 0.97) and can be fertilized. Moreover, we found that a high ROS level could affect the cumulus expansion, which may result in anovulation disorder. The damage could be rescued by melatonin, but the end of cumulus expansion was 3h earlier than anticipation, validating that MCO has the potential for investigating ovarian toxic agents in vitro. We provide a novel approach for building an in vitro ovarian model to recapitulate ovarian functions and test chemical toxicity, suggesting it has the potential for clinical research in the future.

Melatonin Improves Turbot Oocyte Meiotic Maturation and Antioxidant Capacity, Inhibits Apoptosis-Related Genes mRNAs In Vitro

High-quality eggs are essential for the sustainability of commercial aquaculture production. Melatonin is a potent candidate for regulating the growth and maturation of oocytes. Therefore, research on the effect of melatonin on marine fish oocytes in vitro has been conducted. The present study successfully established a culture system of turbot (Scophthalmus maximus) oocytes in vitro and investigated the effect of melatonin on oocyte meiotic maturation, antioxidant capacity, and the expression of apoptosis-related genes. The cultures showed that turbot Scophthalmus maximus late-vitellogenic denuded oocytes, with diameters of 0.5-0.7 mm, had a low spontaneous maturation rate and exhibited a sensitive response to 17α, 20β-dihydroxyprogesterone (DHP) treatment in vitro. Melatonin increased by four times the rate of oocyte germinal vesicle breakdown (GVBD) in a concentration- and time-dependent manner. The mRNA of melatonin receptor 1 (mtnr1) was significantly upregulated in the oocyte and follicle after treatment with melatonin (4.3 × 10^-9 M) for 24 h in vitro, whereas melatonin receptor 2 (mtnr2) and melatonin receptor 3 (mtnr3) remained unchanged. In addition, melatonin significantly increased the activities of catalase, glutathione peroxidase, and superoxide dismutase, as well as the levels of glutathione, while decreasing the levels of malondialdehyde and reactive oxygen species (ROS) levels in turbot oocytes and follicles cultures in vitro. p53, caspase3, and bax mRNAs were significantly downregulated in oocytes and follicles, whereas bcl2 mRNAs were significantly upregulated. In conclusion, the use of turbot late-vitellogenesis oocytes (0.5-0.7 mm) is suitable for establishing a culture system in vitro. Melatonin promotes oocyte meiotic maturation and antioxidative capacity and inhibits apoptosis via the p53-bax-bcl2 and caspase-dependent pathways, which have important potential to improve the maturation and quality of oocytes.

Are ICSI results affected by months and seasons? A retrospective cohort study of fresh and frozen cycles

In present study, we aimed to investigate the effect of seasonal variation on ICSI results both in fresh and frozen embryo transfer cycles. Between January 2007 and December 2019, a total of 4039 ICSI cycles (3227 fresh and 812 frozen ET) which resulted in embryo transfer were included in the study. We found no significant difference in the pregnancy outcome among different seasons and months. The best results were obtained for spring (41.0%) and the least for winter (37.1%) in fresh cycles and the best for spring (42.5%) and the least for winter (29.7%) in FET cycles. In monthly distribution, the best results were obtained for September (57.0%) and the least for November (24.1%) in fresh cycles and the best for October (49.3%) and the least for December (20.2%) in FET cycles. Our study did not show any significant influence of the months or seasons on clinical pregnancy rates in either fresh and frozen embryo transfers. However, the difference among months in frozen cycles was notable although it did not reach statistical significance. It can be suggested that the strict control of reproductive hormones especially in fresh cycles as well as the standardized laboratory temperature minimize the influence of seasonal effect on ICSI outcome.

Role of Melatonin in Bovine Reproductive Biotechnology

Melatonin has profound antioxidant activity and numerous functions in humans as well as in livestock and poultry. Additionally, melatonin plays an important role in regulating the biological rhythms of animals. Combining melatonin with scientific breeding management has considerable potential for optimizing animal physiological functions, but this idea still faces significant challenges. In this review, we summarized the beneficial effects of melatonin supplementation on physiology and reproductive processes in cattle, including granulosa cells, oocytes, circadian rhythm, stress, inflammation, testicular function, spermatogenesis, and semen cryopreservation. There is much emerging evidence that melatonin can profoundly affect cattle. In the future, we hope that melatonin can not only be applied to cattle, but can also be used to safely and effectively improve the efficiency of animal husbandry.

Antioxidants supplementation improves the quality of in vitro produced ovine embryos with amendments in key development gene expressions

The present study assessed the effects of supplementation of different antioxidants on oocyte maturation, embryo production, reactive oxygen species (ROS) production and expression of key developmental genes. In this study, using ovine as an animal model, we tested the hypothesis that antioxidant supplementation enhanced the developmental competence of oocytes. Ovine oocytes aspirated from local abattoir-derived ovaries were subjected to IVM with different concentrations of antioxidants [(Melatonin, Ascorbic acid (Vit C), alpha-tocopherol (Vit E), Sodium selenite (SS)]. Oocytes matured without any antioxidant supplementation were used as controls. The oocytes were assessed for maturation rates and ROS levels. Further, embryo production rates in terms of cleavage, blastocysts and total cell numbers were evaluated after performing in vitro fertilization. Real-Time PCR analysis was used to evaluate the expression of stress related gene (SOD-1), growth related (GDF-9, BMP-15), and apoptosis-related genes (BCL-2 and BAX). We observed that maturation rates were significantly higher in alpha-tocopherol (100 μM; 92.4%) groups followed by melatonin (30 μM; 89.1%) group. However, blastocyst rates in ascorbic acid (100 μM; 19.5%), melatonin (30 μM; 18.4%), alpha-tocopherol (100 μM; 18.2%), and sodium selenite (20 μM; 16.9%) groups were significantly higher (P 0.05) than that observed in the control groups. Total cell numbers in blastocysts in the melatonin, ascorbic acid and alpha-tocopherol groups were significantly higher than those observed in sodium selenite and control groups. ROS production was reduced in groups treated with melatonin (30 μM), vitamin C (100 μM), sodium selenite (20 μM) and α-tocopherol (200 μM) compared with that observed in the control group. Supplementation of antioxidants caused the alterations in mRNA expression of growth, stress, and apoptosis related gene expression in matured oocytes. The results recommend that antioxidants alpha-tocopherol (200 μM), sodium selenite (40 μM), melatonin (30 μM) and ascorbic acid (100 μM) during IVM reduced the oxidative stress by decreasing ROS levels in oocytes, thus improving embryo quantity and quality.

Therapeutic role of melatonin on acrylamide-induced hepatotoxicity in pinealectomized rats: Effects on oxidative stress, NF-κB signaling pathway, and hepatocellular proliferation

Acrylamide (AA) is formed in some foods by the cooking process at high temperatures, and it could be a carcinogen in humans and rodents. The purpose of the current study was to reveal the possible protective effects of melatonin against AA-induced hepatic oxidative stress, hepatic inflammation, and hepatocellular proliferation in pinealectomized rats. Hence, the sham and pinealectomized rats were consecutively given AA alone (25 mg/kg) or with melatonin (10 mg/kg) for 21 days. Melatonin acts as an antioxidant, anti-inflammatory, and antiapoptotic agent and introduces as a therapeutic strategy for AA-induced hepatotoxicity. Melatonin supplementation reduced AA-caused liver damage by decreasing the serum AST, ALT, and ALP levels. Melatonin raised the activities of SOD and CAT and levels of GSH and suppressed hepatic inflammation (TNF-α) and hepatic oxidative stress in liver tissues. Moreover, histopathological alterations and the disturbances in immunohistochemical expression of NF-κB and Ki67 were improved after melatonin treatment in AA-induced hepatotoxicity. Overall, our results demonstrate that melatonin supplementation exhibits adequate hepatoprotective effects against hepatotoxicity of AA on pinealectomized rat liver architecture and the tissue function through the equilibration of oxidant/antioxidant status, the regulation of cell proliferation and the suppression of the release of proinflammatory cytokines.

Seasonal Variation of Melatonin Concentration and mRNA Expression of Melatonin-Related Genes in Developing Ovarian Follicles of Mares Kept under Natural Photoperiods in the Southern Hemisphere

This study investigated the seasonal variations in mRNA expression of FSH (Fshr), LH (Lhr) receptors, melatonin (Mt1 and Mt2) receptors, melatonin-synthetizing enzymes (Asmt and Aanat) and melatonin concentration in developing follicles from mares raised in natural photoperiods. For one year, ultrasonographic follicular aspiration procedures were performed monthly, and small (<20 mm), medium (20 to 35 mm) and large (>35 mm) follicles were recovered from five mares. One day before monthly sample collections, an exploratory ultrasonography conducted to record the number and the size of all follicles larger than 15 mm. The total number of large follicles were higher during the spring/summer (8.2 ± 1.9) than during autumn/winter (3.0 ± 0.5). Compared to autumn/winter seasons, there was an increase of Fshr and Aanat mRNA expressions in small, medium and large follicles, an increase of Lhr and Asmt mRNA expressions in medium and large follicles and an increase of Mt1 and Mt2 mRNA expressions in small and large follicles during spring/summer. The melatonin levels in follicular fluid were also higher during the spring/summer seasons. The present data show that melatonin locally upregulates the mRNA expression of Mt1 and Mt2 receptors and melatonin-forming enzymes in mare developing follicles during reproductive seasons.

Aging-Related Ovarian Failure and Infertility: Melatonin to the Rescue

Aging has a major detrimental effect on the optimal function of the ovary with changes in this organ preceding the age-related deterioration in other tissues, with the middle-aged shutdown leading to infertility. Reduced fertility and consequent inability to conceive by women in present-day societies who choose to have children later in life leads to increased frustration. Melatonin is known to have anti-aging properties related to its antioxidant and anti-inflammatory actions. Its higher follicular fluid levels relative to blood concentrations and its likely synthesis in the oocyte, granulosa, and luteal cells suggest that it is optimally positioned to interfere with age-associated deterioration of the ovary. Additionally, the end of the female reproductive span coincides with a significant reduction in endogenous melatonin levels. Thus, the aims are to review the literature indicating melatonin production in mitochondria of oocytes, granulosa cells, and luteal cells, identify the multiple processes underlying changes in the ovary, especially late in the cessation of the reproductive life span, summarize the physiological and molecular actions of melatonin in the maintenance of normal ovaries and in the aging ovaries, and integrate the acquired information into an explanation for considering melatonin in the treatment of age-related infertility. Use of supplemental melatonin may help preserve fertility later in life and alleviate frustration in women delaying childbearing age, reduce the necessity of in vitro fertilization–embryo transfer (IVF-ET) procedures, and help solve the progressively increasing problem of non-aging-related infertility in women throughout their reproductive life span. While additional research is needed to fully understand the effects of melatonin supplementation on potentially enhancing fertility, studies published to date suggest it may be a promising option for those struggling with infertility.

Reactive oxygen species and ovarian diseases: Antioxidant strategies

Reactive oxygen species (ROS) are mainly produced in mitochondria and are involved in various physiological activities of the ovary through signaling and are critical for regulating the ovarian cycle. Notably, the imbalance between ROS generation and the antioxidant defense system contributes to the development of ovarian diseases. These contradictory effects have critical implications for potential antioxidant strategies that aim to scavenge excessive ROS. However, much remains to be learned about how ROS causes various ovarian diseases to the application of antioxidant therapy for ovarian diseases. Here, we review the mechanisms of ROS generation and maintenance of homeostasis in the ovary and its associated physiological effects. Additionally, we have highlighted the pathological mechanisms of ROS in ovarian diseases and potential antioxidant strategies for treatment.

Coping with Oxidative Stress in Reproductive Pathophysiology and Assisted Reproduction: Melatonin as an Emerging Therapeutical Tool

Infertility is an increasing global public health concern with socio-psychological implications for affected couples. Remarkable advances in reproductive medicine have led to successful treatments such as assisted reproductive techniques (ART). However, the search for new therapeutic tools to improve ART success rates has become a research hotspot. In the last few years, pineal indolamine melatonin has been investigated for its powerful antioxidant properties and its role in reproductive physiology. It is considered a promising therapeutical agent to counteract the detrimental effects associated with oxidative stress in fertility treatments. The aim of the present narrative review was to summarize the current state of the art on the importance of melatonin in reproductive physiology and to provide a critical evaluation of the data available encompassing basic, translational and clinical studies on its potential use in ART to improve fertility success rates.

Azoxystrobin exposure impairs meiotic maturation by disturbing spindle formation in mouse oocytes

Fungicides are a type of pesticide used to protect plants and crops from pathogenic fungi. Azoxystrobin (AZO), a natural methoxyacrylate derived from strobilurin, is one of the most widely used fungicides in agriculture. AZO exerts its fungicidal activity by inhibiting mitochondrial respiration, but its cytotoxicity to mammalian oocytes has not been studied. In this study, we investigated the effect of AZO exposure on mouse oocyte maturation to elucidate the underlying mechanisms of its possible reproductive toxicity. We found that AZO exposure disturbed meiotic maturation by impairing spindle formation and chromosome alignment, which was associated with decreased microtubule organizing center (MTOC) integrity. Moreover, AZO exposure induced abnormal mitochondrial distribution and increased oxidative stress. The AZO-induced toxicity to oocytes was relieved by melatonin supplementation during meiotic maturation. Therefore, our results suggest that AZO exposure impairs oocyte maturation not only by increasing oxidative stress and mitochondrial dysfunction, but also by decreasing MTOC integrity and subsequent spindle formation and chromosome alignment.

Therapeutic Effect of Melatonin in Premature Ovarian Insufficiency: Hippo Pathway Is Involved

Objective

Premature ovarian insufficiency (POI) is a female reproductive disorder of unknown etiology with no definite pathogenesis. Melatonin (MT) is an endogenous hormone synthesized mainly by pineal cells and has strong endogenous effects in regulating ovarian function. To systematically explore the pharmacological mechanism of MT on POI therapy, a literature review approach was conducted at the signaling pathways level.

Methods

Relevant literatures were searched and downloaded from databases, including PubMed and China National Knowledge Infrastructure, using the keywords “premature ovarian insufficiency,” “Hippo signaling pathways,” and “melatonin.” The search criteria were from 2010 to 2022. Text mining was also performed.

Results

MT is involved in the regulation of Hippo signaling pathway in a variety of modes and has been correlated with ovarian function.

Conclusions

The purpose of this review is to summarize the research progress of Hippo signaling pathways and significance of MT in POI, the potential crosstalk between MT and Hippo signaling pathways, and the prospective therapy.

2,4,6-triiodophenol exhibits embryotoxicity to pre-implantation mouse embryos in an in vitro exposure model

2,4,6-triiodophenol (TIP), a novel type of halophenolic disinfection byproducts, has been widely detected in water bodies, even in drinking water. Recently, TIP has drawn increasing concerns on account of considerable developmental toxicity towards lower organisms and cytotoxicity for mammalian cells. However, it remains unknown about its toxicity on mammalian pre-implantation embryos. Here, by exposing mouse zygotes derived in vitro fertilization to TIP, which ranged from 5 to 50 μM, we found that TIP impaired the quality of pre-implantation mouse embryos in a dose-dependent manner, inducing decline of both total and trophectoderm cell numbers, enhancing caspase 3/7 activity and reactive oxygen species generation, though it did not decrease blastocyst formation efficiency. For the sake that only high qualified embryos are able to implant in endometrium and generate health body finally, we applied a previously modified in vitro culture system to assess TIP-exposed blastocysts' further developmental potency beyond pre-implantation stage. Surprisingly, although the exposed dose was only 5 μM and TIP was removed as soon as the zygotes reached blastocyst stage, these blastocysts still nearly lost their implantation and egg cylinder formation ability, exhibiting abnormal embryonic lineage differentiation pattern as well. Therefore, our study not only entirely shows TIP embryonic toxicity on mouse pre-implantation embryos, but also proposes a model to evaluate embryotoxicity from the zygote to egg cylinder stage.

Use of giant unilamellar lipid vesicles as antioxidant carriers in in vitro culture medium of bovine embryos

Giant unilamellar vesicles (GUVs) are composed of lipophilic layers and are sensitive to the action of reactive oxygen species (ROS). The use of GUVs as microcarriers of biological macromolecules is particularly interesting since ROS produced by gametes or embryos during in vitro culture can induce the opening of pores in the membrane of these vesicles and cause the release of their content. This study investigated the behavior of GUVs [composed of 2-dioleoyl-sn-glycero-3-phosphocholine and 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine-N-(lissamine rhodamine B sulfonyl)] in co-culture with in vitro produced bovine embryos, as well as their embryotoxicity and effectiveness as cysteine carriers in culture medium. Embryonic developmental rates were unaffected, demonstrating the absence of toxicity of GUVs co-cultured with the embryos. No increase of intracellular ROS levels was observed in the embryos co-cultured with GUVs, indicating that the higher lipid content of the culture environment resulting from the lipid composition of the GUV membrane itself did not increase oxidative stress. Variations in the diameter and number of GUVs demonstrated their sensitivity to ROS produced by embryos cultured under conditions that generate oxidative stress. Encapsulation of cysteine in GUVs was found to be more effective in controlling the production of ROS in embryonic cells than direct dilution of this antioxidant in the medium. In conclusion, the use of GUVs in in vitro culture was found to be safe since these vesicles did not promote toxic effects nor did they increase intracellular ROS concentrations in the embryos. GUVs were sensitive to oxidative stress, which resulted in structural changes in response to the action of ROS. The possible slow release of cysteine into the culture medium by GUV rupture would therefore favor the gradual supply of cysteine, prolonging its presence in the medium. Thus, the main implication of the use of GUVs as cysteine microcarriers is the greater effectiveness in preventing the intracytoplasmic increase of ROS in in vitro produced bovine embryos.

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.

Melatonin increases growth properties in human dermal papilla spheroids by activating AKT/GSK3β/β-Catenin signaling pathway

Background

Melatonin, a neurohormone, maybe involved in physiological processes, such as antioxidation, anti-inflammation, and hair growth. In the present study, we investigated the effects of melatonin on proliferation and intracellular signaling in DP cells using a three-dimensional (3D) spheroid culture system that mimics the in vivo hair follicle system.

Methods

DP cells were incubated in monolayer (2D) and 3D spheroid culture systems. The expression levels of melatonin receptors in DP cells were analyzed using quantitative reverse transcription polymerase chain reaction (qRT-PCR) and western blotting. The effect of melatonin on the hair-inductive property of DP cells was analyzed using a WST-1-based proliferation assay, determination of DP spheroid size, expression analysis of DP signature genes, and determination of β-catenin stabilization in DP cells. The AKT/GSK3β/β-catenin signaling pathway associated with melatonin-induced β-catenin stabilization in DP cells was investigated by analyzing changes in upstream regulator proteins, including AKT, GSK3β, and their phosphorylated forms.

Results

The expression levels of the melatonin receptors were higher in human DP cells than in human epidermal keratinocytes and human dermal fibroblast cells. Comparing the expression level according to the human DP cell culture condition, melatonin receptor expression was upregulated in the 3D culture system compared to the traditional two-dimensional monolayer culture system. Cell viability analysis showed that melatonin concentrations up to 1 mM did not affect cell viability. Moreover, melatonin increased the diameter of DP cell 3D spheroids in a dose-dependent manner. Immunoblotting and qRT-PCR analysis revealed that melatonin upregulated the expression of hair growth-related genes, including alkaline phosphatase, bone morphogenetic protein 2, versican, and wingless-int 5A, in a melatonin receptor-dependent manner. Cell fractionation analysis showed that melatonin increased the nuclear localization of β-catenin. This result correlated with the increased transcriptional activation of T-cell factor/lymphoid enhancer factor-responsive luciferase induced by melatonin treatment. Interestingly, melatonin induced the phosphorylation of protein kinase B/AKT at serine 473 residue and GSK-3β at serine 9 residue. To determine whether AKT phosphorylation at serine 473 induced β-catenin nuclear translocation through GSK3β phosphorylation at serine 9, the PI3K/AKT inhibitor LY294002 was cotreated with melatonin. Immunoblotting showed that LY294002 inhibited melatonin-induced phosphorylation of GSK3β at serine 9 residue and β-catenin activation.

Conclusion

Collectively, this report suggests that melatonin promotes growth properties by activating the AKT/GSK3β/β-catenin signaling pathway through melatonin receptors.

Effects of Melatonin and/or Magnesium Supplementation on Biomarkers of Inflammation and Oxidative Stress in Women with Polycystic Ovary Syndrome: a Randomized, Double-Blind, Placebo-Controlled Trial

Magnesium and melatonin are known to exert multiple beneficial effects including anti-inflammatory and antioxidant actions. This study was designed to determine the effects of magnesium and/or melatonin supplementation on metabolic profiles in women with polycystic ovary syndrome (PCOS). This randomized double-blind, placebo-controlled trial was conducted among 84 subjects with PCOS aged 18-40 years old. Patients were randomly assigned based on the random block procedure to take magnesium, melatonin, magnesium plus melatonin, or placebo for 8 weeks. Fasting blood samples were taken at baseline and after the intervention to quantify related variables. After the 8-week intervention, an insignificant marginal difference was seen in waist circumference (WC) between groups (P = 0.085). Magnesium-melatonin co-supplementation resulted in more reductions in hirsutism compared with other groups (P < 0.001). Serum levels of tumor necrosis factor-α (TNF-α) declined significantly in the melatonin and co-supplementation groups compared to baseline (P < 0.05). Also, magnesium plus melatonin was associated with a more increase in total antioxidant capacity (TAC) levels, as compared to the other treatment groups (P = 0.001). Overall, we found a favorable effect of co-supplementation of magnesium and melatonin for 8 weeks in women with PCOS on hirsutism, serum TNF-α, and TAC levels. Furthermore, melatonin independently contributed to decreased serum values of TNF-α.Clinical trial registration number http://www.irct.ir : IRCT20191130045556N1, January 2020.

Alterations of Cortisol and Melatonin Production by the Theca Interna Cells of Porcine Cystic Ovarian Follicles

Simple Summary

The mechanism of follicular cyst formation is largely unknown but changes in follicular composition are known to be involved. In particular, there is abnormal hormone secretion in cystic follicles. Here, we found there was disruption of hormone secretion in the fluid of cystic follicles in sows. The glucocorticoid receptor was highly expressed, and the melatonin receptor was weakly expressed in cystic follicles compared with control follicles. Thus, secretion of steroid hormones in cystic follicles is disrupted and disturbances in signaling via cortisol and melatonin are involved in the development of follicular cysts in sows.

Abstract

(1) Background: Cortisol and melatonin (MT) act in regulating follicular development. We hypothesized that abnormal levels of cortisol, MT, and steroids in theca interna cells might be involved in the development of follicular cysts in sows. (2) Methods: To test this hypothesis, we measured the mRNA levels of enzymes involved in steroid hormone synthesis, the glucocorticoid receptor (GR), and melatonin receptors (MTRs) in theca interna cells of cystic and normal porcine follicles. (3) Results: The concentrations of estradiol, progesterone, and cortisol were greater in cystic follicles than in control ones (p = 0.034, p = 0.020, p = 0.000), but the concentration of MT was significantly lower (p = 0.045). The levels of GR, 11β-HSD1, and 11β-HSD2 were higher in cystic follicles than in control l follicles. MT types 1 and 2 were significantly lower in cystic follicles (p < 0.05). The mRNA expression levels of genes encoding the steroid hormone synthesis enzymes, steroidogenic acute regulatory protein (StAR), recombinant cytochrome P45011A1 (CYP11A1), and 3β-hydroxysteroid dehydrogenase (3β-HSD) in theca interna cells of cystic follicles were significantly higher than in control follicles. Thus, there was disruption of hormone secretion in the fluid of cystic follicles in sows. (4) Conclusions: The levels of steroid hormones, cortisol and MT are disrupted in porcine cystic follicles.

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.

Stress associated ovarian dysfunctions in a seasonal breeder Funambulus pennanti: Role of glucocorticoids and possible amelioration by melatonin

Studies have shown that stress caused by lack of physical activity disrupts the normal pattern of glucocorticoid secretion which adversely affects the reproductive axis. We studied the effect of chronic movement restriction on ovarian responses in the Indian Palm Squirrel Funambulus pennanti, a highly active diurnal rodent. Physical restraint of squirrels induced stress that led to a significant increase in plasma cortisol, corticosterone and decreased 17β-estradiol level leading to follicular atresia. Ovarian Reactive Oxygen Species (ROS) content, lipid peroxidation (LPO), activities of superoxide dismutase (SOD) and catalase (CAT) enzymes increased in restrained squirrels. Elevated ROS increased the oxidative load that led to ovarian cell death as evidenced by increased Bax and decreased Bcl2 expression causing further decline in Aromatase and ERα proteins. To elaborate the mechanism(s) involved in stress induced glucocorticoid mediated oxidative damages to the ovary we extended our study by exposing ovaries in vitro to the synthetic glucocorticoid dexamethasone (200 μM). We observed that glucocorticoid receptor (GR) expression was significantly increased in dexamethasone treated ovaries in vitro with a decrease in expression of Nrf2 and HO-1 proteins. Melatonin supplementation (10 nM) along with dexamethasone significantly decreased ovarian ROS production, lipid peroxidation and increased antioxidant enzyme activities by improving the expression of Nrf2 and HO-1, reinstating the cellular redox homeostasis. Therefore, it can be suggested that physical restraint induced glucocorticoid and its receptor activation interfered with the ovarian antioxidant defense mechanism. Melatonin via its receptor MT1 significantly alleviated ovarian damages acting as a cytoprotective agent.

Treatment Progress in Diminished Ovarian Reserve: Western and Chinese Medicine

Diminished ovarian reserve (DOR), generally defined as a decreased number or quality of oocytes, has a significant impact on quality of life and fertility in women. In recent years, the incidence of DOR has been increasing and the ages of patients are younger. The search for an effective DOR treatment has emerged as one of the preeminent research topics in reproductive health. An effective DOR therapy would improve ovarian function, fertility, and quality of life in patients. In this review we evaluated DOR treatment progress both in Western medicine and Chinese medicine, and elucidated the characteristics of each treatment.

Membrane Melatonin Receptors Activated Cell Signaling in Physiology and Disease

The pineal hormone melatonin has attracted great scientific interest since its discovery in 1958. Despite the enormous number of basic and clinical studies the exact role of melatonin in respect to human physiology remains elusive. In humans, two high-affinity receptors for melatonin, MT1 and MT2, belonging to the family of G protein-coupled receptors (GPCRs) have been cloned and identified. The two receptor types activate Gi proteins and MT2 couples additionally to Gq proteins to modulate intracellular events. The individual effects of MT1 and MT2 receptor activation in a variety of cells are complemented by their ability to form homo- and heterodimers, the functional relevance of which is yet to be confirmed. Recently, several melatonin receptor genetic polymorphisms were discovered and implicated in pathology-for instance in type 2 diabetes, autoimmune disease, and cancer. The circadian patterns of melatonin secretion, its pleiotropic effects depending on cell type and condition, and the already demonstrated cross-talks of melatonin receptors with other signal transduction pathways further contribute to the perplexity of research on the role of the pineal hormone in humans. In this review we try to summarize the current knowledge on the membrane melatonin receptor activated cell signaling in physiology and pathology and their relevance to certain disease conditions including cancer.

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.

Meta-analysis of melatonin treatment and porcine somatic cell nuclear transfer embryo development

Porcine somatic cell nuclear transfer (SCNT) plays an important role in many areas of research. However, the low efficiency of SCNT in porcine embryos limits its applications. Porcine embryos contain high concentrations of lipid, which makes them vulnerable to oxidative stress. Some studies have used melatonin to reduce reactive oxygen species damage. At present there are many reports concerning the effect of exogenous melatonin on porcine SCNT. Some studies suggest that the addition of melatonin can increase the number of blastocyst cells, while others indicate that melatonin can reduce the number of blastocyst cells. Therefore, a meta-analysis was carried out to resolve the contradiction. In this study, a total of 63 articles from the past 30 years were analyzed, and six papers were finally selected. Through the analysis, it was found that the blastocyst rate was increased by adding exogenous melatonin. Melatonin had no effect on cleavage rate or the number of blastocyst cells, but did decrease the number of apoptotic cells. This result is crucial for future research on embryo implantation.

The potential neuroprotective effect of allicin and melatonin in acrylamide-induced brain damage in rats

Acrylamide (ACR) is an unsaturated monomer that served various fields; however, it is a potent neurotoxin. The target of the present study is to explore the neuroprotective efficacy of allicin and melatonin on ACR-induced neurotoxicity. Thirty-six male adult rats were non-selectively separated into six groups: placebo, allicin (20 mg/kg b.w daily per os), melatonin (10 mg/kg b.w 3 times/week per os), ACR (50 mg/kg b.w daily per os), ACR-allicin, and ACR-melatonin at the same doses as the preceding groups. The assessment of brain biomarkers, neurotransmitters, antioxidative status, Nrf2 signaling pathway, and histopathological analyses was performed following 21 days. ACR exposure induced brain lipid and DNA oxidative damage as well as reduced the glutathione (GSH) levels. The obvious brain oxidative injuries contributed to distinct brain dysfunction that was assured by alteration of brain neurotransmitters (serotonin, dopamine, acetylcholine, and acetylcholinesterase) and pathological brain lesions. Furthermore, ACR exposure increased hydroxy deoxyguanosine (8-OHdG), tumor necrosis factor-α (TNF-α), and amyloid protein (AB1-42). Finally, the mRNA transcripts of brain Keap-1, Nrf2, and NF-kB were upregulated after ACR intoxication. Interestingly, allicin and melatonin alleviated the ACR-induced brain damage assessed by the normalization of the mentioned analyses. The present study demonstrated the protective role of both allicin and melatonin in ACR-prompted neuropathy by alleviation of redox imbalance and enhancement of neurotransmitters as well as relieving DNA damage and anti-inflammatory effect.

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.

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.

Melatonin ameliorates endocrine dysfunction and defective sperm integrity associated with high-fat diet-induced obesity in male Wistar rats

Obesity (OBS) has been established as a link to male hypogonadism with consequent infertility. Previous studies have shown that melatonin (MEL) modulates hypothalamic-pituitary-gonadal function. The present study therefore investigated the hypothesis that MEL supplementation would attenuate spermatogenic and steroidogenic dysfunctions associated with obesity induced by high-fat diet (HFD). Twenty-four adult male Wistar rats (n = 6/group) were used: control group received vehicle (normal saline), obese group received 40% high-fat diet and distilled water, MEL-treated group received MEL (4 mg/kg), and OBS + MEL group received MEL and 40% HFD and the treatment lasted for 12 weeks. HFD caused increased body weight, glucose intolerance, plasma triglyceride and low-density lipoprotein cholesterol/ very low-density lipoprotein cholesterol and malondialdehyde, as well as decreased antioxidant capacity, high-density lipoprotein cholesterol, gonadotrophin-releasing hormone, follicle-stimulating hormone and testosterone and altered sperm parameters. However, all these alterations were attenuated when supplemented with MEL. Taken together, these results indicate that HFD exposure causes endocrine dysfunction and disrupted sperm parameters in obese animals, which are accompanied by lipid peroxidation/defective antioxidant capacity. In addition, the present results suggest that melatonin supplementation restores endocrine function and sperm integrity in obese rat model by suppression of oxidative stress-dependent mechanism.

Integrated Analysis of Transcriptome and Histone Modifications in Granulosa Cells During Ovulation in Female Mice

The ovulatory luteinizing hormone (LH) surge induces rapid changes of gene expression and cellular functions in granulosa cells (GCs) undergoing luteinization. However, it remains unclear how the changes in genome-wide gene expression are regulated. H3K4me3 histone modifications are involved in the rapid alteration of gene expression. In this study, we investigated genome-wide changes of transcriptome and H3K4me3 status in mouse GCs undergoing luteinization. GCs were obtained from mice treated with equine chorionic gonadotropin (hCG) before, 4 hours, and 12 hours after human chorionic gonadotropin injection. RNA-sequencing identified a number of upregulated and downregulated genes, which could be classified into 8 patterns according to the time-course changes of gene expression. Many genes were transiently upregulated or downregulated at 4 hours after hCG stimulation. Gene Ontology terms associated with these genes included steroidogenesis, ovulation, cumulus-oocyte complex (COC) expansion, angiogenesis, immune system, reactive oxygen species (ROS) metabolism, inflammatory response, metabolism, and autophagy. The cellular functions of DNA repair and cell growth were newly identified as being activated during ovulation. Chromatin immunoprecipitation-sequencing revealed a genome-wide and rapid change in H3K4me3 during ovulation. Integration of transcriptome and H3K4me3 data identified many H3K4me3-associated genes that are involved in steroidogenesis, ovulation, COC expansion, angiogenesis, inflammatory response, immune system, ROS metabolism, lipid and glucose metabolism, autophagy, and regulation of cell size. The present results suggest that genome-wide changes in H3K4me3 after the LH surge are associated with rapid changes in gene expression in GCs, which enables GCs to acquire a lot of cellular functions within a short time that are required for ovulation and luteinization.

Peroxiredoxin 1 Controls Ovulation and Ovulated Cumulus-Oocyte Complex Activity through TLR4-Derived ERK1/2 Signaling in Mice

Peroxiredoxins (PRDXs) are expressed in the ovary and during ovulation. PRDX1 activity related to the immuno-like response during ovulation is unknown. We investigated the roles of Prdx1 on TLR4 and ERK1/2 signaling from the ovulated cumulus–oocyte complex (COC) using Prdx1-knockout (K/O) and wild-type (WT) mice. Ovulated COCs were collected 12 and 16 h after pregnant mare serum gonadotropin/hCG injection. PRDX1 protein expression and COC secretion factors (Il-6, Tnfaip6, and Ptgs2) increased 16 h after ovulated COCs of the WT mice were obtained. We treated the ovulated COCs in mice with LPS (0.5 μg/mL) or hyaluronidase (Hya) (10 units/mL) to induce TLR4 activity. Intracellular reactive oxygen species (ROS), cumulus cell apoptosis, PRDX1, TLR4/P38/ERK1/2 protein expression, and COC secretion factors’ mRNA levels increased in LPS- and Hya-treated COCs. The ERK inhibitor (U0126) and Prdx1 siRNA affected TLR4/ERK1/2 expression. The number and cumulus expansion of ovulated COCs by ROS were impaired in Prdx1 K/O mice but not in WT ones. Prdx1 gene deletion induced TLR4/P38/ERK1/2 expression and cumulus expansion genes. These results show the controlling roles of PRDX1 for TLR4/P38/ERK1/2 signaling activity in ovulated mice and the interlink of COCs with ovulation.

Adipose-Derived Mesenchymal Stem Cells: A Promising Tool in the Treatment of pre mature ovarian failure

Despite being rare, primary ovarian insufficiency (POI) is a significant cause of infertility and deficiency of ovarian hormone in women. Several health risks are also associated with POI, which include dry eye syndrome, reduced density of bones and enhanced fracture risks, troublesome menopausal symptoms, early development of cardiovascular disease, and psychological effects such as declined cognition, reduced perceived psychological support, anxiety, and depression. Replacing premenopausal levels of ovarian sex steroids through proper hormone replacement therapy could improve the quality of life for POI women and ameliorate related health risks. Herein, POI and its complications, in addition to hormone replacement therapies, which are safe and effective, are discussed. It is proposed that the use of HRT) Hormone replacement therapy (formulations which mimic normal production of ovarian hormones could reduce POI-associated morbidity rates if they are continued by the age 50, which is approximately the natural age of menopause. Particular populations of POI women are also addressed, which include those with enhanced risk of ovarian or breast cancer, those with Turner syndrome, those approaching natural menopause, and those who are breastfeeding. It is generally predicted that stem cell-based therapies would be both safe and effective. In fact, several types of cells have been described as safe, though their effectiveness and therapeutic application are yet to be defined. Several factors exist which could affect the results of treatment, such as cell handling, ex-vivo preparation strategies, variations in tissue of origin, potency, and immunocompatibility. Accordingly, cell types potentially effective in regenerative medicine could be recognized. Notably, products of MSCs from various sources of tissues show different levels of regenerative capabilities. The ultimate focus of the review is on adipose tissue-derive MCSs (ADMSCs), which possess exceptional features such as general availability, great ability to proliferate and differentiate, immunomodulatory capabilities, and low immunogenicity.

Pigment epithelium-derived factor negates oxidative stress in mouse oocytes

Molecular changes, caused by various environmental factors, affect the quality and developmental potential of oocytes. Oxidative stress (OS) is a major factor involved in various gynecologic disorders and/or in aging. Recent studies suggest that elevated reactive oxygen species (ROS) hamper oocyte quality and future embryonic development. Pigment epithelium-derived factor (PEDF) is a pleiotropic protein, known for its antiangiogenic, anti-inflammatory, and antioxidative properties. Our previous findings demonstrate the antioxidative role of rPEDF in maintaining granulosa cell viability. In the current study, we examined the ability of PEDF to negate the adverse impact of OS on oocytes. Maturation rate of oocytes exposed to OS was significantly lower than that of control oocytes. The number of mtDNA copies in OS-exposed oocytes was significantly higher than in control oocytes (>3 times), whereas ATP concentration was significantly lower. Oocytes exposed to OS demonstrated impaired chromosome arrangement at the metaphase plate. PEDF significantly improved maturation rate of untreated OS-exposed oocytes. Moreover, mtDNA copy number, ATP concentration, and chromosome arrangement at the metaphase plate in rPEDF-treated OS-exposed oocytes were restored to the level of control oocytes. Our findings demonstrate that OS hampers the ability of oocytes to undergo proper in vitro maturation. The energetic balance of OS-exposed oocyte is characterized by excessive mtDNA replication and reduced ATP concentration; it hampers the ability of oocytes to perform high fidelity chromosome segregation. PEDF alleviates this damage, improves the rate of oocyte maturation, and preserves mtDNA level and ATP content, thus enabling oocytes to form proper metaphase plate and improve oocyte competence.

Research progress of melatonin (MT) in improving ovarian function: a review of the current status

Melatonin (MT) is an endogenous hormone mainly synthesized by pineal cells, which has strong endogenous effects of eliminating free radicals and resisting oxidative damages. Melatonin (MT) can not only regulate the body’s seasonal and circadian rhythms; but also delay ovarian senescence, regulate ovarian biological rhythm, promote follicles formation, and improve oocyte quality and fertilization rate. This review aimd to provide evidence concerning the synthesis and distribution, ovarian function, and role of MT in development of follicles and oocytes. Moreover, the role of MT as antioxidative, participating in biological rhythm regulation, was also reviewed. Furthermore, the effects of MT on various ovarian related diseases were analyzed, particularly for the ovarian aging and polycystic ovary syndrome (PCOS).

The effect of oral melatonin supplementation on MT-ATP6 gene expression and IVF outcomes in Iranian infertile couples: a nonrandomized controlled trial

This study aims to evaluate the effect of melatonin supplementation on the outcomes of in vitro fertilization (IVF) and mitochondrial adenosine triphosphate production (MT-ATP6) gene expression in Iranian infertile couples. A single-blind nonrandomized controlled trial was conducted, recruiting 90 infertile couples who underwent IVF at an infertility center in Tehran, Iran. Patients who were assigned to the intervention group received melatonin as a supplementation to the standard controlled ovarian stimulation (COS). The control group received a COS protocol only. Primary outcome was the mRNA level of the MT-ATP6 gene in cumulus cells of ovarian follicles. Secondary outcomes were the mean number of mature oocytes retrieved, the embryo quality, and biochemical and clinical pregnancy rates. The mRNA level of the MT-ATP6 gene in cumulus cells between intervention and control groups was not statistically different (0.931 vs.1; P ˃ 0.05). The mean number of poor-quality embryos was significantly lower in the intervention group than that in the control group (0.27 vs. 0.80; P = 0.028). The biochemical and clinical pregnancy rates were higher in the intervention group (24% vs. 14%, P = 0.089, and 14% vs. 7%, P = 0.302, respectively); however, the difference was not significant. Melatonin supplementation did not increase the odds of clinical pregnancy and the number of mature oocytes retrieved, but significantly reduced the number of low-quality embryos. More extensive studies focusing on the level of MT-ATP6 gene expression in the oocyte or blastomere cells may further elucidate the effect of supplementation with melatonin in infertile couples who have poor clinical outcomes. Trial registration: Current Controlled Trials: IRCT2015042912307N4.