Potential roles of the melatonin system in the promotion of ovarian estradiol secretion in the sea cucumber, Apostichopus japonicus

Melatonin (MT), synthesized from tryptophan, modulates reproduction through its interaction with melatonin receptors (MTNRs). While its functions in vertebrates are well established, the MT system remains poorly understood in echinoderms. To elucidate MT synthesis regulation, we examined AjAsmt, a pivotal enzyme in MT biosynthesis, to determine its tissue-specific distribution in Apostichopus japonicus. AjAsmt was predominantly expressed in the nerve ring, polian vesicle, intestine, and muscle, with significantly reduced intestinal expression post-spawning, suggesting a role in ovarian development and physiological regulation. Building on this, we characterized the molecular and functional properties of AjMTNR using computational analyses and in vitro assays. MT treatment triggered AjMTNR internalization and elevated intracellular cAMP and Ca2+ levels. Notably, AjMTNR was highly expressed in the gonads, prompting an investigation into MT's role in estradiol (E2) secretion. In vitro experiments confirmed that MT stimulates E2 secretion in ovarian tissue in a concentration-dependent manner. These findings enhance our understanding of the MT system's physiological functions and provide valuable insights for the reproductive management and aquaculture of A. japonicus.

Circadian rhythm disruption and polycystic ovary syndrome: a systematic review and meta-analysis

Objective

The aim of our systematic review and meta-analysis was to determine if circadian rhythm disruption (CRD) is associated with polycystic ovary syndrome (PCOS). Our objective was to pool the overall mean differences in biomarkers of CRD (including melatonin levels, morning and evening cortisol levels, and sleep efficiency) between PCOS patients and controls. We hypothesized that CRD will be more prominent in patients with PCOS.

Data sources

A systematic search of PubMed, Scopus, Embase, ClinicalTrials.Gov, and the Cochrane Database of Systematic Reviews was conducted from inception until 2024 using the following MeSH terms "circadian rhythm" OR "sleep disturbance" OR "melatonin" AND "polycystic ovary syndrome." Citation search supplemented the systematic database search.

Study eligibility criteria

Inclusion criteria were women with PCOS, original case-control, cross-sectional, and cohort studies that identify parameters of CRD (melatonin, cortisol, and sleep disturbance). Exclusion criteria were women with endocrine and metabolic co-morbidities, menopausal women, case reports, review studies, animal studies, abstracts, and conference presentations. There was no time restriction for year of publication.

Study appraisal and synthesis methods

Two investigators (T.H. and P.R.) assessed the quality of the studies included using the Newcastle-Ottawa Scale. Forest plots were created using the Open Meta Analyst software. Publication bias was assessed in Egger's and Begg's tests.

Results

A total of 16 studies were included in the systematic review and 12 studies were included in the meta-analysis (N=1,100 women [531 PCOS patients and 569 controls]). Pooled analysis showed that the mean difference in melatonin levels between PCOS patients and controls was 14.294 pg/mL, 95% CI [6.895, 21.693]. The overall mean difference in morning and evening cortisol between PCOS patients and controls was 1.103 pg/mL, 95% CI [-1.058, 3.265], and 3.574 pg/mL, 95% CI [1.741, 5.407], respectively. Pooled difference in mean sleep efficiency scores between PCOS patients and controls was -4.059, 95% CI [-6.752, -1.366]. Risk of bias assessment showed that NOS scores ranged from 7 to 9.

Conclusions

Our meta-analysis provides evidence that circadian rhythm disruption is positively associated with polycystic ovary syndrome. This is substantiated by differences in parameters indicative of circadian rhythm disruption, including melatonin levels, evening cortisol, and sleep efficiency.

The impact of maternal sleep during pregnancy on childhood health: A systematic review

The impact of maternal gestational sleep on pregnancy complications and birth outcomes has been well established by several systematic reviews/meta-analyses. However, the long-term health effect on children has not been summarized. Given the emerging evidence in maternal sleep is revealing new significant insights into this research field, the present review was particularly designed to systematically review and critically appraise existing population-based studies on the association between maternal sleep during pregnancy and childhood health. Available full-text studies that focused on the association were taken into account in this review; 6462 titles and abstracts and 36 full articles were screened from three databases, PubMed, Embase, and Web of Science, among which 24 studies were ultimately included in the synthesis. Based on childhood health indicators these studies covered, four areas of outcomes including metabolism, neurocognition, sleep, and allergy were categorized and summarized. Our analyses show that maternal gestational poor sleep and sleep disturbance negatively impact multiple aspects of childhood health, though the quality of the studies should be improved. The results inform future studies that should ideally reach out touching on broader health concerns and draw out longer follow-up periods, accompanying adopting more specific methods of assessing maternal sleep and children's health outcomes.

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.

Melatonin mediates the BMP4/MAPK signaling pathway to alleviate zearalenone-induced abnormal embryonic development in mice

Zearalenone (ZEA) is a common mycotoxin found in crops that poses a threat to human health, particularly the female reproductive system. Here, we show that exposing mouse zygotes to ZEA in vitro significantly impairs embryo development, leading to embryo arrest. Remarkably, treatment of ZEA-exposed mouse embryos with melatonin significantly improved the blastocyst rates from approximately 40 % to nearly 80 %. Furthermore, melatonin effectively mitigates the harmful effects of ZEA exposure by reducing reactive oxygen species (ROS) levels, preventing mitochondrial dysfunction, and decreasing cell apoptosis. Following embryo transplantation, the birth rate of offspring increased markedly from 7.2 % to 23.62 %. Further research revealed that the abnormal elevation of bone morphogenetic protein 4 (BMP4) signaling induced by ZEA exposure, coupled with the inhibition of the downstream mitogen-activated protein kinase (MAPK) signaling pathway, contributes to developmental blockade in ZEA-exposed mouse embryos. Melatonin rescued ZEA-induced defects in mouse embryo development by inhibiting BMP4 signaling and regulating the MAPK pathway. Moreover, the Bmp4 inhibitor Noggin or its receptor inhibitor DMH-1 could also effectively ameliorate the ZEA-induced impairment of embryo development. Taken together, these findings underscore the potential of melatonin as a therapeutic intervention for addressing the adverse effects of ZEA exposure on mouse embryos.

Perinatal psychiatry: balancing maternal-fetal exposures to mental disorders and drug treatments

INTRODUCTION

The potential effects of psychotropic medications during pregnancy must be balanced against those of untreated maternal mental illness, which has been under-appreciated as an exposure that impacts development.

METHODS

This is an expert, non-systematic literature review of the effect of maternal stress and psychotropic medication on fetal development.

RESULTS

Studies on the outcomes of pregnancy and child development following exposures to stress, mental disorders and psychotropic medications during pregnancy are reviewed. Alterations in pharmacokinetics due to the physiology of pregnancy may change the efficacy of drug treatment. The impact of stress and mental health conditions in pregnancy is difficult to separate from other exposures; however, these exposures have adverse effects on fetal and child development independent from medication treatment. A focus on optimal treatment to reduce psychiatric symptoms, which is the justification for use of the drug, is critical. Building healthy fetal brains through adequate maternal essential nutrient intake holds promise to support reduction of the risk for adverse neurodevelopmental outcomes.

CONCLUSION

Untreated maternal mental illness is an exposure that impacts outcomes, the course of comorbid medical disorders, and offspring development. The current knowledge base dictates that treatment of psychiatric disorders be prioritized in the benefit-harm decision process.

Developmental competence of ovum pick up derived Sahiwal cow oocytes in maturation media supplemented with cysteamine and melatonin

Antioxidants, cysteamine and melatonin, have an important role on mitochondrial membrane potential (ΔΨM), in vitro nuclear maturation and developmental competence of oocytes. A comprehensive study was planned to investigate the effect of cysteamine 50 µM and melatonin 10-9 mol L-1 as antioxidants on ΔΨM, in vitro nuclear maturation and developmental competence of ovum pick up (OPU) derived Sahiwal Cow oocytes. Culturable grade OPU derived Sahiwal oocytes were divided in to three in vitro maturation groups cultured in TCM-199 supplemented with cysteamine 50 µM, melatonin 10-9 mol L-1 and TCM-199 alone, for assessing nuclear maturation by Lamin/ DAPI and developmental competence of oocytes. ΔΨM was assessed by JC-1 staining in pre-maturation group and post-maturation cysteamine, melatonin and control groups. Red to green ratio of fluorescence intensity on JC-1 staining was higher (p < 0.05) in melatonin (1.19 ± 0.04) and cysteamine (1.09 ± 0.04) supplementation groups as compared to control (0.81 ± 0.10) and pre-maturation (0.71 ± 0.03) groups. ΔΨM improved post-maturation in all the treatment and control groups as compared to pre-maturation group (0.71 ± 0.03). Melatonin supplementation improved (p < 0.05) M-II stage oocytes (6.5 ± 0.65, 68.13 per cent) as compared to cysteamine supplemented (5.25 ± 0.25, 55.63 per cent) and control (4.75 ± 0.25, 50.63 per cent) groups. COC expansion rate was higher in antioxidant supplemented group. Fertilization rate, cleavage rate and blastocyst rate were higher (p < 0.05) in melatonin supplemented group (92.31, 59.17 and 20.56 per cent) as compared to cysteamine supplemented (82.96, 41.48 and 11.39 per cent) and control (75.28, 27.59 and 5.19 per cent) groups, respectively. In conclusion, cysteamine and melatonin supplementation as antioxidants in the in vitro maturation media improved (p < 0.05) ΔΨM. Significant improvement in MII stage oocytes, cleavage and blastocyst rate in OPU derived Sahiwal cow oocytes by supplementation of melatonin to the IVM medium as compared to cysteamine supplemented and control groups. Melatonin improved both cytoplasmic (ΔΨM is improved) and nuclear maturation (no. of MII oocytes) by acting both as intracellular and extracellular antioxidant against ROS, thereby improving developmental competence of OPU derived Sahiwal Cow oocytes. Cysteamine supplementation improved cytoplasmic maturation by increasing GSH content thereby improving ΔΨM but not the nuclear maturation.

Evaluation of cytoprotective effects of cannabidiol on neuroinflammation and neurogenesis process in rat offsprings

Natural compounds include complex chemical compounds that exist in plants, animals and microbes. Due to their broad spectrum of pharmacological and biochemical actions, they have been widely used to treat multifactorial diseases, including cancer. In addition, their demonstrated neuroprotective properties strongly support their use in the treatment of neurological diseases. The present study investigated the effect of cannabidiol (CBD), which can easily cross the placental barrier and is known to have anti-inflammatory effects, on fetal neuroinflammation and neurogenesis in a systemic inflammation model during pregnancy. Herein, 12 weeks adult pregnant rats (n = 30) were randomly divided into 5 groups with 6 rats in each group as follows: Control, LPS (lipopolysaccharide, i.p.), LPS+CBD 5 mg/kg (i.p.), LPS+CBD10 mg/kg (i.p.) and LPS+CBD30 mg/kg (i.p.). After the injections, blood samples of rats were collected, fetuses and placentas were taken by hysterectomy. Histopathological analysis, immunohistochemical staining, ELISA and immunoblotting analysis were performed to investigate neuroinflammatory and neurogenesis parameters in fetal brain and placenta tissues. Our findings indicated that CBD administration importantly suppressed the inflammatory process in the rat fetal brain by decreasing interleukin-1beta (IL-1β) and tumor necrosis factor-alpha (TNF-α) levels and diminishing nuclear factor kappa B (NF-κB) activation. Moreover, CBD inhibited lipopolysaccharide (LPS)-induced increasing levels of neuroinflammation-associated proteins, including glial fibrillary acidic protein (GFAP), S100B and cAMP-response element binding protein (CREB). These results suggest that CBD usage in pregnancy with inflammation conditions may be an effective therapeutic option for preventing conditions that may cause neuroinflammation in the fetal brain and adversely affect neurogenesis.

Melatonin protects bovine oocyte from βHB-induced oxidative stress through the Nrf2 pathway

Accumulation of ketone bodies in the blood or tissues can trigger ketosis, exerting detrimental effects on bovine oocytes maturation. Exposure to its primary component, β-hydroxybutyric acid (βHB), disrupts mitochondrial function, culminating in the excessive buildup of reactive oxygen species (ROS) and subsequent initiation of apoptosis in oocytes. These ultimately result in poor oocyte quality. Melatonin, recognized for its endogenous antioxidant properties, is capable of mitigating ROS levels and enhancing the expression of antioxidant enzymes. In this study, we explored the protective effects of melatonin on the damages induced by βHB. Melatonin was added at a concentration of 10-9 M to the culture medium on bovine oocytes. Parameters including first polar body extrusion rate, mitochondrial membrane potential, ROS, cell apoptosis were assessed. Results showed that melatonin could restore bovine oocyte maturation rate, enhance mitochondrial function, reduce cell apoptosis rate, and mitigate oxidative stress levels. Notably, Nrf2 signaling pathway inhibitor ML385 significantly attenuated the protective effects of melatonin on oxidative stress induced by βHB exposure. In summary, our study demonstrates that melatonin can protect oocytes from oxidative stress induced by βHB exposure, with indications that this protective mechanism may be mediated through the Nrf2 pathway.

Proteomic analysis reveals the alleviation of follicular development defects in offspring mice under DEHP exposure by melatonin

BACKGROUND

Environmental endocrine disruptor Di (2-ethylhexyl) phthalate (DEHP) widely affects the health of human and animals including the reproductive system. However, there are few studies on the protective strategies for the maternal DEHP exposure on follicular development of offspring. In the present study, we established a model of lactation female mice exposed to DEHP and reported the effects and potential mechanism of melatonin on the follicular development of offspring.

RESULTS

Our data showed that melatonin rescued the decrease of primordial follicles, antral follicles and oocyte number (increased by 74.2%) of offspring caused by maternal DEHP exposure from the primordial follicle formation stage. Proteomic analysis showed that melatonin altered the ovarian steroidogenesis, lipid metabolism, signal transduction, and DNA damage-related proteins. Melatonin reversed the disorder of lipid metabolism caused by DEHP and stabilized ovarian hormone secretase level. Molecular docking results indicated that DEHP/MEHP/melatonin binds to HSD17B2 to form a stable conformation, which may explain the reduction in 17β-estradiol induced by DEHP. Moreover, melatonin restored granulosa cell proliferation, reduced oxidative stress and DNA damage-related apoptosis, enhanced mitochondrial function, and protected ovarian cells. Besides, melatonin enhanced gap junction and promoted intercellular communication, which facilitate the formation of primordial follicles and the growth and development of antral follicles. In addition, melatonin rescued the oocyte defects of offspring caused by maternal DEHP exposure.

CONCLUSIONS

Taken together, our data showed that melatonin could alleviate the damage of follicular development and abnormal ovarian steroidogenesis of offspring caused by maternal DEHP exposure.

Evaluation of the effect of exogenous melatonin on the placenta and inflammatory cytokines in rats submitted to chronic alcohol consumption

Global alcohol consumption by pregnant women is approximately 9.8%. This consumption can hinder the interaction of the placenta with the fetus and increase levels of oxidative stress by altering and deregulating the expression of cytokines, leading to complications such as slow intrauterine development, such as low birth weight, premature babies and even stillbirths. It is known that melatonin is a natural antioxidant that acts mainly on the liver and also on various organs such as the ovary, placenta and the fetus itself. Melatonin can freely cross the placenta and exert effects on the mother and fetus. The present work aimed to analyze the effects of exogenous administration of melatonin during pregnancy on the placenta of rats subjected to chronic alcohol consumption. 30 albino rats were used, divided into 3 groups: Control - 10 pregnant rats that will not receive alcohol; Alcohol - 10 pregnant rats subjected to chronic alcohol consumption; Alcohol + Melatonin - 10 pregnant rats subjected to alcohol consumption associated with melatonin. Alcohol was administered at a dose of 3g/kg by gavage, while melatonin was administered at night at a dose of 0.8mg/kg intraperitoneally. The placentas were weighed and analyzed histopathologically, morphometrically and immunohistochemically. The results showed a significant reduction in placental weight in the alcohol group, disorganization in the labyrinthine zone and reduction of maternal and fetal vessels in the alcohol group. There was strong staining for TNF α and VEGF factors in the alcohol group. And as for PCNA, the control group and the alcohol + melatonin group showed the highest percentages of positive cells. And in relation to apoptosis, there was strong staining in the junctional zone of the placentas of females in the alcohol group. Therefore, it is concluded that melatonin has the potential to protect against the oxidative damage of ethanol in placental cells and can also regulate the generation of inflammatory cytokines.

A, Guadarrama Gándara CG, Escobar C, Guerrero-Vargas NN. Maternal exposure to dim light at night induces behavioral alterations in the adolescent and adult offspring Wistar rat

Introduction

Access to electric light has exposed living organisms to varying intensities of light throughout the 24 h day. Dim light at night (DLAN) is an inappropriate signal for the biological clock, which is responsible for the circadian organization of physiology. During the gestational period, physiological adaptations occur to ensure a successful pregnancy and optimal fetal development. Environmental maternal conditions, such as disruptions of maternal circadian rhythms, could negatively affect offspring health. We have previously demonstrated that exposure of female Wistar rats to DLAN results in circadian, metabolic, and behavioral alterations. A relevant behavior during adolescence is social play, primarily regulated by the nucleus accumbens (NAc) which is crucial for the proper performance of important behaviors in adulthood. Throughout development, microglia are responsible for the remodeling of diverse brain regions via synaptic pruning. During adolescence, this process occurs within the NAc, where immune-mediated remodeling directly impacts social play behavior.

Methods

This study investigated the effects of maternal exposure to DLAN or a light-dark cycle (LD) before (5 weeks) and during the gestational period (21-23 days) on the metabolism and behavior of offspring in adolescence and adulthood. Body mass was measured every 5 days from postnatal day 1 (PN1) to PN25 and every 10 days from PN40 to PN90; food consumption was monitored weekly from PN40 to PN90. Social play behavior was evaluated at PN40. The quantification and morphology of microglia in the NAc were measured on PN30. An open field test was conducted at PN60, and anhedonia test was assessed at PN90.

Results and discussion

Male and female offspring from mothers exposed to DLAN showed increased body mass gain at PN25. DLAN male offspring had lower food consumption, while DLAN females exhibited increased food consumption. In social play behavior, no differences were found between DLAN and LD female offspring. In contrast, DLAN male offspring exhibited a significant decrease in social play behavior compared to LD animals, which was associated with higher numbers of microglia in the NAc that had more ramified morphology. Importantly, at PN90, DLAN offspring presented increased anxiety-like behaviors. These results demonstrate that DLAN exposure induces intergenerational behavioral alterations that persist until adulthood.

Melatonin improves endometrial receptivity and embryo implantation via MT2/PI3K/LIF signaling pathway in sows

BACKGROUND

Increased backfat thickness of sows in early gestation is negative to reproductive performance. Endometrial receptivity is an important determinant of reproductive success, but it is unclear whether the effect of sow backfat thickness on litter size is associated with endometrial receptivity and whether melatonin treatment may have benefits. The present study seeks to answer these questions through in vitro and in vivo investigations.

RESULTS

Excessive lipid deposition and lower melatonin levels in the uterus are detrimental to endometrial receptivity and embryo implantation in high backfat thickness sows. In cells treated with melatonin, the MT2/PI3K/LIF axis played a role in reducing lipid accumulation in porcine endometrial epithelium cells and improved endometrial receptivity. Furthermore, we found a reduction of lipids in the uterus after eight weeks of intraperitoneal administration of melatonin to HFD mice. Notably, melatonin treatment caused a significant reduction in the deposition of endometrial collagen, an increase in the number of glands, and repair of the pinopode structure, ultimately improving endometrial receptivity, promoting embryo implantation, and increasing the number of litter size of mice.

CONCLUSIONS

Collectively, the finding reveals the harmful effects of high backfat thickness sows on embryo implantation and highlight the role of melatonin and the MT2/PI3K/LIF axis in improving endometrial receptivity by enhancing metabolism and reducing the levels of uterine lipids in obese animals.

Pharmacological and non-pharmacological interventions for improving endometrial receptivity in infertile patients with polycystic ovary syndrome: a comprehensive review of the available evidence

Direct and indirect evidence suggests that endometrial receptivity may play a crucial role in the reduced fertility rate of women with polycystic ovary syndrome (PCOS). Various pharmacological and non-pharmacological strategies with potential effects on endometrial receptivity in patients with PCOS have been proposed. The aim of this study was to summarize the rationale and the clinical and experimental evidence of interventions tested for improving endometrial receptivity in infertile patients with PCOS. A systematic review was conducted by consulting electronic databases. All interventions with a potential influence on endometrial receptivity in infertile patients with PCOS were evaluated, and their main biological mechanisms were analysed. In total, 24 interventions related to endometrial receptivity were identified. Notwithstanding a strong biological rationale, no intervention aimed at improving endometrial receptivity in women with PCOS is supported by an adequate body of evidence, limiting their use in clinical practice. Further high-quality research is needed in this field to limit potentially ineffective and unsafe add-on treatments in infertile patients with PCOS.

Circadian patterns of heart rate variability in fetal sheep after hypoxia-ischaemia: A biomarker of evolving brain injury

Hypoxia-ischaemia (HI) before birth is a key risk factor for stillbirth and severe neurodevelopmental disability in survivors, including cerebral palsy, although there are no reliable biomarkers to detect at risk fetuses that may have suffered a transient period of severe HI. We investigated time and frequency domain measures of fetal heart rate variability (FHRV) for 3 weeks after HI in preterm fetal sheep at 0.7 gestation (equivalent to preterm humans) until 0.8 gestation (equivalent to term humans). We have previously shown that this is associated with delayed development of severe white and grey matter injury, including cystic white matter injury (WMI) resembling that observed in human preterm infants. HI was associated with suppression of time and frequency domain measures of FHRV and reduced their circadian rhythmicity during the first 3 days of recovery. By contrast, circadian rhythms of multiple measures of FHRV were exaggerated over the final 2 weeks of recovery, mediated by a greater reduction in FHRV during the morning nadir, but no change in the evening peak. These data suggest that the time of day at which FHRV measurements are taken affects their diagnostic utility. We further propose that circadian changes in FHRV may be a low-cost, easily applied biomarker of antenatal HI and evolving brain injury. KEY POINTS: Hypoxia-ischaemia (HI) before birth is a key risk factor for stillbirth and probably for disability in survivors, although there are no reliable biomarkers for antenatal brain injury. In preterm fetal sheep, acute HI that is known to lead to delayed development of severe white and grey matter injury over 3 weeks, was associated with early suppression of multiple time and frequency domain measures of fetal heart rate variability (FHRV) and loss of their circadian rhythms during the first 3 days after HI. Over the final 2 weeks of recovery after HI, exaggerated circadian rhythms of frequency domain FHRV measures were observed. The morning nadirs were lower with no change in the evening peak of FHRV. Circadian changes in FHRV may be a low-cost, easily applied biomarker of antenatal HI and evolving brain injury.

Melatonin's Impact on Wound Healing

Melatonin (5-methoxy-N-acetyltryptamine) is an indoleamine compound that plays a critical role in the regulation of circadian rhythms. While melatonin is primarily synthesized from the amino acid tryptophan in the pineal gland of the brain, it can also be produced locally in various tissues, such as the skin and intestines. Melatonin's effects in target tissues can be mediated through receptor-dependent mechanisms. Additionally, melatonin exerts various actions via receptor-independent pathways. In biological systems, melatonin and its endogenous metabolites often produce similar effects. While injuries are common in daily life, promoting optimal wound healing is essential for patient well-being and healthcare outcomes. Beyond regulating circadian rhythms as a neuroendocrine hormone, melatonin may enhance wound healing through (1) potent antioxidant properties, (2) anti-inflammatory actions, (3) infection control, (4) regulation of vascular reactivity and angiogenesis, (5) analgesic (pain-relieving) effects, and (6) anti-pruritic (anti-itch) effects. This review aims to provide a comprehensive overview of scientific studies that demonstrate melatonin's potential roles in supporting effective wound healing.

Postnatal Development of the Circadian Rhythmicity of Human Pineal Melatonin Synthesis and Secretion (Systematic Review)

Introduction: According to current knowledge, at birth, the pineal gland and melatonin receptors are already present and the suprachiasmatic nucleus is largely functional, and noradrenaline, the key pineal transmitter, can be detected in the early foetal period. It is still unclear why the pineal gland is not able to start its own pulsatile synthesis and secretion of melatonin in the first months of life, and as a result, infants during this time are dependent on an external supply of melatonin. Method: The causes and consequences of this physiological melatonin deficiency in human infancy are examined in a systematic review of the literature, in which 40 of 115 initially selected publications were evaluated in detail. The references of these studies were checked for relevant studies on this topic. References from previous reviews by the author were taken into account. Results: The development and differentiation of the pineal gland, the pinealocytes, as the site of melatonin synthesis, and the development and synaptic coupling of the associated predominantly noradrenergic neural pathways and vessels and the associated Lhx4 homebox only occurs during the first year of life. Discussion: The resulting physiological melatonin deficiency is associated with sleep disorders, infant colic, and increased crying in babies. Intervention studies indicate that this deficiency should be compensated for through breastfeeding, the administration of nonpooled donor milk, or through industrially produced chrononutrition made from nonpooled cow's milk with melatonin-poor day milk and melatonin-rich night milk.

Melatonin Regulates the Expression of VEGF and HOXA10 in Bovine Endometrial Epithelial Cells through the SIRT1/PI3K/AKT Pathway

Melatonin plays a critical role in regulating embryo attachment in ruminants. While numerous studies have investigated its effects on early embryo development in vitro, the precise mechanisms by which melatonin influences the receptivity of endometrial epithelial cells in dairy cows remain unclear. The prerequisite for embryo implantation is the specific physiological condition of the endometrium that allows the embryo to implant, also known as endometrial receptivity. In addition to this, endometrial cells undergo processes such as proliferation, differentiation, and renewal, which makes the embryo more easily implanted. In this study, bovine endometrial epithelial cells were cultured and treated with melatonin, Silent Information Regulator 1 (SIRT1) inhibitor (EX527), and protein kinase B (AKT) phosphorylation inhibitor (periposine). RT-qPCR, Western blot, and immunofluorescence analysis were performed to investigate the effects of melatonin on the expression of target gene (SIRT1); cell proliferative genes, phosphatidylinositol-4,5-bisphosphate 3-Kinase (PI3K), AKT, cyclinD1, cyclinE1; and receptive genes (Leukemia Inhibitory Factor (LIF), Vascular Endothelial Growth Factor (VEGF), Homeobox Structure Gene 10 (HOXA10)). Additionally, microRNA (miRNA) mimics and inhibitors were used to transfect the cells to study the regulatory relationship between miRNA and receptive genes. Results indicated that melatonin activates the PI3K/AKT signaling pathway, upregulates cyclinD1 and cyclinE1, and promotes the proliferation of bovine endometrial epithelial cells. Melatonin also upregulated the expression of VEGF and HOXA10 and downregulated the expression of bta-miR-497 and bta-miR-27a-3p through SIRT1/PI3K/AKT signaling pathway. Further, bta-miR-497 and bta-miR-27a-3p were found to negatively regulate VEGF and HOXA10, respectively. Therefore, melatonin regulates the expression of VEGF and HOXA10 through the SIRT1/PI3K/AKT pathway and promotes the establishment of receptivity in bovine endometrial epithelial cells.

Melatonin rescues pregnant female mice and their juvenile offspring from high fat diet-induced alzheimer disease neuropathy

High fat diet (HFD) is a prime factor, which contributes to the present epidemic of metabolic syndrome. Prolonged intake of HFD induces oxidative stress (OS) that in turn causes neuroinflammation, neurodegeneration, insulin resistance, amyloid burden, synaptic dysfunction and cognitive impairment hence leading to Alzheimer's disease neuropathy. Melatonin (secreted by the Pineal gland) has the potential to nullify the toxic effects of reactive oxygen species (ROS) and have been shown to ameliorate various complications induced by HFD in rodent models. This study aimed to assess the neurotherapeutic effects of melatonin on HFD-induced neuroinflammation and neurodegeneration mediated by OS in pregnant female mice and their offspring. Western blotting, immunohistochemistry and antioxidant enzyme assays were used for quantification of samples from the hippocampal region of the brain of pregnant albino mice and their offspring. Short- and long-term memory was assessed by Y-maze and Morris Water Maze tests. HFD significantly induced OS leading to AD like neuropathology in the pregnant mice and their offspring while melatonin administration simultaneously with the HFD significantly prevented this neuropathy. This study reports that melatonin exerts these effects through the stimulation of SIRT1/Nrf2/HO-1 pathway that in turn reduces the HFD-induced OS and its downstream signaling. In conclusion melatonin prevents HFD-induced multiple complications that ultimately leads to the memory dysfunction in pregnant female mice and their successive generation via activation of SIRT1/Nrf2 signaling pathway.

Genome-Wide Analysis of Genetic Diversity and Selection Signatures in Zaobei Beef Cattle

This investigation provides a comprehensive analysis of genomic diversity and selection signatures in Zaobei beef cattle, an indigenous breed known for its adaptation to hot and humid climates and superior meat quality. Whole-genome resequencing was conducted on 23 Zaobei cattle, compared with 46 Simmental cattle to highlight genetic distinctions. Population structure analysis confirmed the genetic uniqueness of Zaobei cattle. Using methods such as DASDC v1.01, XPEHH, and θπ ratio, we identified 230, 232, and 221 genes through DASDC, including hard sweeps, soft sweeps, and linkage sweeps, respectively. Coincidentally, 109 genes were identified when using XPEHH and θπ ratio methods. Together, these analyses revealed eight positive selection genes (ARHGAP15, ZNF618, USH2A, PDZRN4, SPATA6, ROR2, KCNIP3, and VWA3B), which are linked to critical traits such as heat stress adaptation, fertility, and meat quality. Moreover, functional enrichment analyses showed pathways related to autophagy, immune response, energy metabolism, and muscle development. The comprehensive genomic insights gained from this study provide valuable knowledge for breeding programs aimed at enhancing the beneficial traits in Zaobei cattle.

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.

Dysmaturation of sleep state and electroencephalographic activity after hypoxia-ischaemia in preterm fetal sheep

Antenatal hypoxia-ischaemia (HI) in preterm fetal sheep can trigger delayed evolution of severe, cystic white matter injury (WMI), in a similar timecourse to WMI in preterm infants. We therefore examined how severe hypoxia-ischaemia affects recovery of electroencephalographic (EEG) activity. Chronically instrumented preterm fetal sheep (0.7 gestation) received 25 min of complete umbilical cord occlusion (UCO, n = 9) or sham occlusion (controls, n = 9), and recovered for 21 days. HI was associated with a shift to lower frequency EEG activity for the first 5 days with persisting loss of EEG power in the delta and theta bands, and initial loss of power in the alpha and beta bands in the first 14 days of recovery. In the final 3 days of recovery, there was a marked rhythmic shift towards higher frequency EEG activity after UCO. The UCO group spent less time in high-voltage sleep, and in the early evening (7:02 pm ± 47 min) abruptly stopped cycling between sleep states, with a shift to a high frequency state for 2 h 48 min ± 40 min, with tonic electromyographic activity. These findings demonstrate persisting EEG and sleep state dysmaturation after severe hypoxia-ischaemia. Loss of fetal or neonatal sleep state cycling in the early evening may be a useful biomarker for evolving cystic WMI.

Effects of Dietary Melatonin on Antioxidant Capacity, Immune Defense, and Intestinal Microbiota in Red Swamp Crayfish (Procambarus clarkii)

The aim of this study was to investigate the effects of melatonin (MT) feed supplementation on the antioxidant capacity, immune defense, and intestinal flora in Procambarus clarkii (P. clarkii). Six groups of P. clarkii were fed test feeds containing different levels of MT: 0 mg/kg (control), 22.5, 41.2, 82.7, 165.1, and 329.2 mg/kg for a duration of 2 months. The specific growth rate, hepatosomatic index, and condition factor were recorded highest in the test group of shrimp fed an MT concentration of 165.1 mg/kg. Compared to the control group, the rate of apoptosis was lower in hepatopancreas cells of P. clarkii supplemented with high concentrations of MT. Analyses of antioxidant capacity and immune-response-related enzymes in the hepatopancreas indicated that dietary supplementation of MT significantly augmented both the antioxidant system and immune responses. Dietary MT supplementation significantly increased the expression levels of antioxidant-immunity-related genes and decreased the expression levels of genes linked to apoptosis. Dietary MT was associated with an elevation in the abundance of the Firmicutes and a reduction in the abundance of the Proteobacteria in the intestines; besides, resulting in an increase in the abundance of beneficial bacteria, such as Lactobacilli. The broken-line model indicated that the suitable MT concentration was 154.09-157.09 mg/kg. MT supplementation enhanced the growth performance of P. clarkii, exerting a positive influence on the intestinal microbiota, and bolstered both immune response and disease resistance. Thus, this study offered novel perspectives regarding the application of dietary MT supplementation within the aquaculture field.

Causal associations between sleep traits and age at natural menopause: A Mendelian randomization study

Observational studies have revealed that several sleep traits can impact ovarian function in women. However, there is no evidence suggesting associations between sleep traits and age at natural menopause (ANM). The objective of this study was to investigate the causal relationship between sleep traits (insomnia, sleep duration, daytime sleepiness) and ANM from the perspective of genetic variation. We selected the single-nucleotide polymorphisms from large-scale genome-wide association studies as instrumental variables and conducted a two-sample Mendelian randomization (MR) analysis on these single-nucleotide polymorphisms, including inverse variance weighting, MR-Egger, weighted median, simple mode and weighted mode. The Steiger test was employed to verify the correct causal directionality. The robustness of the MR analysis was examined through Cochran's Q test, horizontal pleiotropy test, and leave-one-out analysis. The results indicated that insomnia was causally associated with ANM (inverse variance weighting: β = -0.982; 95% CI: -1.852 to -0.111, P = .027), with other analyses confirming the robustness of this finding. Steiger test and reverse MR Analysis validated the absence of a reverse causal association between the two. However, sleep duration and daytime sleepiness did not exhibit a causal effect on ANM. In summary, this study provides initial evidence that insomnia can contribute to an earlier onset of ANM. Nevertheless, further clinical studies are needed to elucidate these findings.

Melatonin in Human Breast Milk and Its Potential Role in Circadian Entrainment: A Nod towards Chrononutrition?

Breastfeeding is the most appropriate source of a newborn's nutrition; among the plethora of its benefits, its modulation of circadian rhythmicity with melatonin as a potential neuroendocrine transducer has gained increasing interest. Transplacental transfer assures melatonin provision for the fetus, who is devoid of melatonin secretion. Even after birth, the neonatal pineal gland is not able to produce melatonin rhythmically for several months (with an even more prolonged deficiency following preterm birth). In this context, human breast milk constitutes the main natural source of melatonin: diurnal dynamic changes, an acrophase early after midnight, and changes in melatonin concentrations according to gestational age and during the different stages of lactation have been reported. Understudied thus far are the factors impacting on (changes in) melatonin content in human breast milk and their clinical significance in chronobiological adherence in the neonate: maternal as well as environmental aspects have to be investigated in more detail to guide nursing mothers in optimal feeding schedules which probably means a synchronized instead of mistimed feeding practice. This review aims to be thought-provoking regarding the critical role of melatonin in chrononutrition during breastfeeding, highlighting its potential in circadian entrainment and therefore optimizing (neuro)developmental outcomes in the neonatal setting.

Maternal circadian rhythm disruption affects neonatal inflammation via metabolic reprograming of myeloid cells

Disruption of circadian rhythm during pregnancy produces adverse health outcomes in offspring; however, the role of maternal circadian rhythms in the immune system of infants and their susceptibility to inflammation remains poorly understood. Here we show that disruption of circadian rhythms in pregnant mice profoundly aggravates the severity of neonatal inflammatory disorders in both male and female offspring, such as necrotizing enterocolitis and sepsis. The diminished maternal production of docosahexaenoic acid (DHA) and the impaired immunosuppressive function of neonatal myeloid-derived suppressor cells (MDSCs) contribute to this phenomenon. Mechanistically, DHA enhances the immunosuppressive function of MDSCs via PPARγ-mediated mitochondrial oxidative phosphorylation. Transfer of MDSCs or perinatal supplementation of DHA relieves neonatal inflammation induced by maternal rhythm disruption. These observations collectively demonstrate a previously unrecognized role of maternal circadian rhythms in the control of neonatal inflammation via metabolic reprograming of myeloid cells.

Melatonin-mediated actions and circadian functions that improve implantation, fetal health and pregnancy outcome

This review summarizes data related to the potential importance of the ubiquitously functioning antioxidant, melatonin, in resisting oxidative stress and protecting against common pathophysiological disorders that accompany implantation, gestation and fetal development. Melatonin from the maternal pineal gland, but also trophoblasts in the placenta, perhaps in the mitochondria, produce this molecule as a hedge against impairment of the uteroplacental unit. We also discuss the role of circadian disruption on reproductive disorders of pregnancy. The common disorders of pregnancy, i.e., stillborn fetus, recurrent fetal loss, preeclampsia, fetal growth retardation, premature delivery, and fetal teratology are all conditions in which elevated oxidative stress plays a role and experimental supplementation with melatonin has been shown to reduce the frequency or severity of these conditions. Moreover, circadian disruption often occurs during pregnancy and has a negative impact on fetal health; conversely, melatonin has circadian rhythm synchronizing actions to overcome the consequences of chronodisruption which often appear postnatally. In view of the extensive findings supporting the ability of melatonin, an endogenously-produced and non-toxic molecule, to protect against experimental placental, fetal, and maternal pathologies, it should be given serious consideration as a supplement to forestall the disorders of pregnancy. Until recently, the collective idea was that melatonin supplements should be avoided during pregnancy. The data summarized herein suggests otherwise. The current findings coupled with the evidence, published elsewhere, showing that melatonin is highly protective of the fertilized oocyte from oxidative damage argues in favor of its use for improving pregnancy outcome generally.

Negative photoperiod induces an increase in the number of ovulations in dairy cattle

This study sought to examine the impact of negative photoperiod on the incidence of multiple ovulations and pregnancies in dairy cattle. The study population consisted of 5,373 pregnant cows in their third or greater lactation that experienced their first post-partum pregnancy after spontaneous estrus. The positive photoperiod (increasing day-length) extends from December 22 to June 21, whereas the negative photoperiod (decreasing day-length) extends from June 22 to December 21. The odds ratios (ORs) for multiple ovulations and pregnancies in cows that became pregnant during the negative photoperiod and the remaining cows that became pregnant during the positive photoperiod were 1.4 and 1.3 (P < 0.0001), respectively. The ORs for cows that became pregnant ≥ 90 days in milk and the remaining cows that became pregnant < 90 days in milk were 4.3 and 4.1 (P < 0.0001), respectively. No significant differences were detected in the monthly rates of multiple ovulations or pregnancies during positive and negative photoperiods. Thus, the present study demonstrates that the ovarian function in cows is related to changes in day-length, with decreasing day-length being associated with greater multiple ovulation and pregnancy rates. The present study also shows that positive and negative photoperiods exhibit different trends. The results of this study are consistent with a growing body of work demonstrating the effects of photoperiod patterns on the reproductive physiology of cows, with clear implications for twin pregnancy prevention.

Melatonin Use during Pregnancy and Lactation Complicated by Oxidative Stress: Focus on Offspring's Cardiovascular-Kidney-Metabolic Health in Animal Models

Cardiovascular-kidney-metabolic (CKM) syndrome has emerged as a major global public health concern, posing a substantial threat to human health. Early-life exposure to oxidative stress may heighten vulnerability to the developmental programming of adult diseases, encompassing various aspects of CKM syndrome. Conversely, the initiation of adverse programming processes can potentially be thwarted through early-life antioxidant interventions. Melatonin, originally recognized for its antioxidant properties, is an endogenous hormone with diverse biological functions. While melatonin has demonstrated benefits in addressing disorders linked to oxidative stress, there has been comparatively less focus on investigating its reprogramming effects on CKM syndrome. This review consolidates the current knowledge on the role of oxidative stress during pregnancy and lactation in inducing CKM traits in offspring, emphasizing the underlying mechanisms. The multifaceted role of melatonin in regulating oxidative stress, mediating fetal programming, and preventing adverse outcomes in offspring positions it as a promising reprogramming strategy. Currently, there is a lack of sufficient information in humans, and the available evidence primarily originates from animal studies. This opens up new avenues for novel preventive intervention in CKM syndrome.

Obstructive Sleep Apnea-Associated Intermittent Hypoxia-Induced Immune Responses in Males, Pregnancies, and Offspring

Obstructive sleep apnea (OSA), a respiratory sleep disorder associated with cardiovascular diseases, is more prevalent in men. However, OSA occurrence in pregnant women rises to a level comparable to men during late gestation, creating persistent effects on both maternal and offspring health. The exact mechanisms behind OSA-induced cardiovascular diseases remain unclear, but inflammation and oxidative stress play a key role. Animal models using intermittent hypoxia (IH), a hallmark of OSA, reveal several pro-inflammatory signaling pathways at play in males, such as TLR4/MyD88/NF-κB/MAPK, miRNA/NLRP3, and COX signaling, along with shifts in immune cell populations and function. Limited evidence suggests similarities in pregnancies and offspring. In addition, suppressing these inflammatory molecules ameliorates IH-induced inflammation and tissue injury, providing new potential targets to treat OSA-associated cardiovascular diseases. This review will focus on the inflammatory mechanisms linking IH to cardiovascular dysfunction in males, pregnancies, and their offspring. The goal is to inspire further investigations into the understudied populations of pregnant females and their offspring, which ultimately uncover underlying mechanisms and therapeutic interventions for OSA-associated diseases.

Melatonin: the placental antioxidant and anti-inflammatory

Melatonin (N-acetyl-5-methoxytryptamine) is an indolamine hormone with many physiological and biological roles. Melatonin is an antioxidant, anti-inflammatory, free radical scavenger, circadian rhythm regulator, and sleep hormone. However, its most popular role is the ability to regulate sleep through the circadian rhythm. Interestingly, recent studies have shown that melatonin is an important and essential hormone during pregnancy, specifically in the placenta. This is primarily due to the placenta's ability to synthesize its own melatonin rather than depending on the pineal gland. During pregnancy, melatonin acts as an antioxidant and anti-inflammatory, which is necessary to ensure a stable environment for both the mother and the fetus. It is an essential antioxidant in the placenta because it reduces oxidative stress by constantly scavenging for free radicals, i.e., maintain the placenta's integrity. In a healthy pregnancy, the maternal immune system is constantly altered to accommodate the needs of the growing fetus, and melatonin acts as a key anti-inflammatory by regulating immune homeostasis during early and late gestation. This literature review aims to identify and summarize melatonin's role as a powerful antioxidant and anti-inflammatory that reduces oxidative stress and inflammation to maintain a favorable homeostatic environment in the placenta throughout gestation.

Premature ovarian insufficiency: a review on the role of tobacco smoke, its clinical harm, and treatment

Premature ovarian insufficiency (POI) is a condition in which the quantity of follicles and the quality of oocytes gradually decrease. This results in an estrogen secretion disorder and abnormal follicle development, which can lead to related diseases, early onset of menopause, sexual dysfunction, and an increased risk of cardiovascular issues, osteoporosis, and depression, among others. This disease significantly impacts the physical and mental health and overall quality of life of affected women. Factors such as genetic abnormalities, oophorectomy, radiotherapy for malignancy, idiopathic conditions, and an unhealthy lifestyle, including smoking, can accelerate the depletion of the follicular pool and the onset of menopause. Extensive research has been conducted on the detrimental effects of tobacco smoke on the ovaries. This article aims to review the advancements in understanding the impact of tobacco smoke on POI, both in vivo and in vitro. Furthermore, we explore the potential adverse effects of common toxicants found in tobacco smoke, such as polycyclic aromatic hydrocarbons (PAHs), heavy metals like cadmium, alkaloids like nicotine and its major metabolite cotinine, benzo[a]pyrene, and aromatic amines. In addition to discussing the toxicants, this article also reviews the complications associated with POI and the current state of research and application of treatment methods. These findings will contribute to the development of more precise treatments for POI, offering theoretical support for enhancing the long-term quality of life for women affected by this condition.

The effect of ionizing radiation on the fetal bone development in pregnant rats: Role of melatonin

Radiation has been widely used in many business sectors over the last century. Our study investigated the possible teratogenic effects of radiation on the bones of rat fetuses and the protective effect of melatonin against these effects. In this study, 15 pregnant female Wistar albino rats were used. These rats were divided into four groups: the control group, melatonin group (10 mg/kg/day), radiation group (0.5 gray), radiation (0.5 gray) + melatonin group (10 mg/kg/day), and sham group (1 mm hanks/day). The skeletal system development of fetuses was examined with double skeletal and scanning electron microscope (SEM), histopathological methods. In our study, fetal weight, placental weight, and fetal morphometric values were found to be statistically significantly decreased in the radiation group compared to the control group (p < .05). In immünohistochemistry (IHC) analysis, alkaline phosphatase, and tartrate-resistant acid phosphatase) concentrations were found to be significantly lower in the radiation group compared to the other groups. In the SEM analysis, it was observed that the amount of calcium and sodium decreased when the radiation group was compared with the other groups. As a result, when exposed to ionizing radiation during pregnancy, melatonin has a protective feature against the negative effects of radiation on the bone development of fetuses. RESEARCH HIGHLIGHTS: In our study, fetuses obtained from pregnant rats exposed to ionizing radiation were examined. In this study, the effect of melatonin on bone development in fetuses exposed to gray ionizing radiation was investigated. There are few studies on our subject in the literature. We believe that our findings will contribute to other planned studies.

Crosstalk Between Aging, Circadian Rhythm, and Melatonin

Circadian rhythms (CRs) are 24-hour periodic oscillations governed by an endogenous circadian pacemaker located in the suprachiasmatic nucleus (SCN), which organizes the physiology and behavior of organisms. Circadian rhythm disruption (CRD) is also indicative of the aging process. In mammals, melatonin is primarily synthesized in the pineal gland and participates in a variety of multifaceted intracellular signaling networks and has been shown to synchronize CRs. Endogenous melatonin synthesis and its release tend to decrease progressively with advancing age. Older individuals experience frequent CR disruption, which hastens the process of aging. A profound understanding of the relationship between CRs and aging has the potential to improve existing treatments and facilitate development of novel chronotherapies that target age-related disorders. This review article aims to examine the circadian regulatory mechanisms in which melatonin plays a key role in signaling. We describe the basic architecture of the molecular circadian clock and its functional decline with age in detail. Furthermore, we discuss the role of melatonin in regulation of the circadian pacemaker and redox homeostasis during aging. Moreover, we also discuss the protective effect of exogenous melatonin supplementation in age-dependent CR disruption, which sheds light on this pleiotropic molecule and how it can be used as an effective chronotherapeutic medicine.

From gestational chronodisruption to noncommunicable diseases: Pathophysiological mechanisms of programming of adult diseases, and the potential therapeutic role of melatonin

During gestation, the developing fetus relies on precise maternal circadian signals for optimal growth and preparation for extrauterine life. These signals regulate the daily delivery of oxygen, nutrients, hormones, and other biophysical factors while synchronizing fetal rhythms with the external photoperiod. However, modern lifestyle factors such as light pollution and shift work can induce gestational chronodisruption, leading to the desynchronization of maternal and fetal circadian rhythms. Such disruptions have been associated with adverse effects on cardiovascular, neurodevelopmental, metabolic, and endocrine functions in the fetus, increasing the susceptibility to noncommunicable diseases (NCDs) in adult life. This aligns with the Developmental Origins of Health and Disease theory, suggesting that early-life exposures can significantly influence health outcomes later in life. The consequences of gestational chronodisruption also extend into adulthood. Environmental factors like diet and stress can exacerbate the adverse effects of these disruptions, underscoring the importance of maintaining a healthy circadian rhythm across the lifespan to prevent NCDs and mitigate the impact of gestational chronodisruption on aging. Research efforts are currently aimed at identifying potential interventions to prevent or mitigate the effects of gestational chronodisruption. Melatonin supplementation during pregnancy emerges as a promising intervention, although further investigation is required to fully understand the precise mechanisms involved and to develop effective strategies for promoting health and preventing NCDs in individuals affected by gestational chronodisruption.

Orchestrated feedback regulation between melatonin and sex hormones involving GPER1-PKA-CREB signaling in the placenta

Maintaining placental endocrine homeostasis is crucial for a successful pregnancy. Pre-eclampsia (PE), a gestational complication, is a leading cause of maternal and perinatal morbidity and mortality. Aberrant elevation of testosterone (T0 ) synthesis, reduced estradiol (E2 ), and melatonin productions have been identified in preeclamptic placentas. However, the precise contribution of disrupted homeostasis among these hormones to the occurrence of PE remains unknown. In this study, we established a strong correlation between suppressed melatonin production and decreased E2 as well as elevated T0 synthesis in PE placentas. Administration of the T0 analog testosterone propionate (TP; 2 mg/kg/day) to pregnant mice from E7.5 onwards resulted in PE-like symptoms, along with elevated T0 production and reduced E2 and melatonin production. Notably, supplementation with melatonin (10 mg/kg/day) in TP-treated mice had detrimental effects on fetal and placental development and compromised hormone synthesis. Importantly, E2 , but not T0 , actively enhanced melatonin synthetase AANAT expression and melatonin production in primary human trophoblast (PHT) cells through GPER1-PKA-CREB signaling pathway. On the other hand, melatonin suppressed the level of estrogen synthetase aromatase while promoting the expressions of androgen synthetic enzymes including 17β-HSD3 and 3β-HSD1 in PHT cells. These findings reveal an orchestrated feedback mechanism that maintains homeostasis of placental sex hormones and melatonin. It is implied that abnormal elevation of T0 synthesis likely serves as the primary cause of placental endocrine disturbances associated with PE. The suppression of melatonin may represent an adaptive strategy to correct the imbalance in sex hormone levels within preeclamptic placentas. The findings of this study offer novel evidence that identifies potential targets for the development of innovative therapeutic strategies for PE.

Night work during pregnancy and small for gestational age: a Danish nationwide register-based cohort study

OBJECTIVE

The aim was to investigate the association between night work during pregnancy and risk of having a small for gestational age (SGA) child.

METHODS

This cohort study had payroll data with detailed information on working hours for employees in all Danish administrative regions (primarily hospital employees) between 2007 and 2015, retrieved from the Danish Working Hour Database. Pregnancies, covariates and outcome were identified from the national birth registry. We used logistic regression to investigate the association between intensity and duration of night work during the first 32 pregnancy weeks and SGA. The adjusted model included age, body mass index, socioeconomic status and smoking. Using quantitative bias analysis and G-estimation, we explored potential healthy worker survivor bias (HWSB).

RESULTS

The final cohort comprised 24 548 singleton pregnancies in 19 107 women, primarily nurses and medical doctors. None of the dimensions of night work were associated with an increased risk of SGA. We found a tendency towards higher risk of SGA in pregnancies where the women stopped having night shifts during pregnancy. Using G-estimation we found an OR<1 for the association between night work and SGA if all workers continued having night work during pregnancy compared with daywork only.

CONCLUSION

We found no increased risk of SGA in association with night work during pregnancy among healthcare workers. G-estimation was not precise enough to estimate the observed indication of HWSB. We need better data on pregnancy discomforts and complications to be able to safely rule out HWSB.

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.

Effectiveness of health literacy and relaxing music on quality of sleep and risk for antenatal depression

Background

Pregnant women experience increased sleep disturbances during the third trimester of their pregnancy, which may result in the development of psychological issues in the perinatal period. There is a dearth of interventional studies that combine health literacy and the provision of music for the benefit of pregnant women in South Asia.

Aim

To determine the effectiveness of a combination of Comprehensive Health literacy And Relaxing Music (CHARM) interventions on quality of sleep and risk for antenatal depression among women visiting antenatal outpatient departments of a tertiary hospital in South India.

Methods

A four-arm parallel-group randomized controlled trial was adopted; 128 low-risk primigravid women were recruited and randomly assigned to the four groups using block randomization. The interventions included relaxing music interventions, comprehensive health-literacy interventions, combinations of both as CHARM interventions, and standard antenatal care. All the interventions were provided for four weeks. The quality of sleep among pregnant women was assessed using the Pittsburgh Sleep Quality Index Scale at baseline and after four weeks of intervention. Women at risk of developing antenatal depression were screened using the Edinburgh Postnatal Depression Scale-Antenatal Version.

Results

Pregnant women who received CHARM interventions had significant improvement in quality of sleep when compared with other interventions (F(3,124) =15.0, P < .001, effect size η p2= 0.27). Also, 38 (29.6%) of the included pregnant women were at risk of developing antenatal depression, which was reduced to 21 (16.4%) following the intervention.

Conclusion

CHARM intervention could promote quality sleep and reduce the risk of developing antenatal depression, thereby improving perinatal mental health.

Absence of melatonin during development impairs craniofacial and dental onset in rats

OBJECTIVE

Herein, we evaluated pinealectomy-induced melatonin absence to determine its effects on craniofacial and dental development in the offspring.

DESIGN

Female Wistar rats in three groups, i.e., intact pregnant rats, pinealectomized pregnant rats (PINX), and pinealectomized pregnant rats subjected to oral melatonin replacement therapy, were crossed 30 days after surgery. The heads of 7-day-old pups were harvested for cephalometric and histological analyses, and maxillae and incisors were collected for mRNA expression analysis.

RESULTS

The PINX pups exhibited a reduction in neurocranial and facial parameters such as a decrease in alveolar bone area, incisor size and proliferation, and an increase in odontoblasts and the dentin layer. Based on incisor mRNA expression analysis, we found that Dmp1 expression was upregulated, whereas Col1a1 expression was downregulated. Maxillary mRNA expression revealed that Rankl expression was upregulated, whereas that of Opn and Osx was downregulated.

CONCLUSION

Our results demonstrated that the absence of maternal melatonin during early life could affect dental and maxillary development in offspring, as well as delay odontogenesis and osteogenesis in maxillary tissues.

CLINICAL RELEVANCE

Our findings suggest that disruptions or a lack of melatonin during pregnancy may cause changes in craniofacial and dental development, at least in animal experiments; however, in humans, these feedings are still poorly understood, and thus careful evaluations of melatonin levels in humans need to be investigated in craniofacial alterations.

Effects of the neonatal intensive care environment on circadian health and development of preterm infants

The circadian system in mammals ensures adaptation to the light-dark cycle on Earth and imposes 24-h rhythmicity on metabolic, physiological and behavioral processes. The central circadian pacemaker is located in the brain and is entrained by environmental signals called Zeitgebers. From here, neural, humoral and systemic signals drive rhythms in peripheral clocks in nearly every mammalian tissue. During pregnancy, disruption of the complex interplay between the mother's rhythmic signals and the fetal developing circadian system can lead to long-term health consequences in the offspring. When an infant is born very preterm, it loses the temporal signals received from the mother prematurely and becomes totally dependent on 24/7 care in the Neonatal Intensive Care Unit (NICU), where day/night rhythmicity is usually blurred. In this literature review, we provide an overview of the fetal and neonatal development of the circadian system, and short-term consequences of disruption of this process as occurs in the NICU environment. Moreover, we provide a theoretical and molecular framework of how this disruption could lead to later-life disease. Finally, we discuss studies that aim to improve health outcomes after preterm birth by studying the effects of enhancing rhythmicity in light and noise exposure.

Melatonin as a Therapy for Preterm Brain Injury: What Is the Evidence?

Despite significant improvements in survival following preterm birth in recent years, the neurodevelopmental burden of prematurity, with its long-term cognitive and behavioral consequences, remains a significant challenge in neonatology. Neuroprotective treatment options to improve neurodevelopmental outcomes in preterm infants are therefore urgently needed. Alleviating inflammatory and oxidative stress (OS), melatonin might modify important triggers of preterm brain injury, a complex combination of destructive and developmental abnormalities termed encephalopathy of prematurity (EoP). Preliminary data also suggests that melatonin has a direct neurotrophic impact, emphasizing its therapeutic potential with a favorable safety profile in the preterm setting. The current review outlines the most important pathomechanisms underlying preterm brain injury and correlates them with melatonin's neuroprotective potential, while underlining significant pharmacokinetic/pharmacodynamic uncertainties that need to be addressed in future studies.

Circular RNA as a Novel Regulator and Promising Biomarker in Polycystic Ovary Syndrome

Polycystic ovary syndrome (PCOS) is a prevalent metabolic and reproductive disorder that causes low fertility in females. Despite its detrimental effects on women's health, care for PCOS has been impeded by its undefined pathogenesis. Thus, there is an urgent need to explore novel biomarkers and therapeutic targets for the diagnosis and treatment of PCOS. Circular RNAs (circRNAs) are a class of noncoding RNAs with covalently closed cyclic structures, present in high abundance, and show development-stage specific expression patterns. Recent studies have demonstrated that circRNAs participate in PCOS progression by modulating various biological functions, including cell proliferation, apoptosis, and steroidogenesis. In addition, circRNAs are widely present in the follicular fluid of women with PCOS, indicating their potential as diagnostic biomarkers and therapeutic targets for PCOS. This review provides the current knowledge of circRNAs in PCOS, including their regulatory functions and molecular mechanisms, and explores their potential as diagnostic biomarkers and therapeutic targets.

Maternal melatonin levels and temporal dietary intake: results from MY-CARE cohort study

Chrononutrition emerges as a novel approach to promote circadian alignment and metabolic health by means of time-of-the-day dietary intake. However, the relationship between maternal circadian rhythm and temporal dietary intake during pregnancy remains understudied. This study aimed to determine the change in melatonin levels in pregnant women across gestation and its association with temporal energy and macronutrient intake. This was a prospective cohort involving 70 healthy primigravidas. During the second and third trimesters, pregnant women provided salivary samples collected at 9:00, 15:00, 21:00, and 3:00 h over a 24 h day for melatonin assay. Data on chrononutrition characteristics were collected using a 3-day food record. Parameters derived from melatonin measurements including mean, amplitude, maximal level, area under the curve with respect to increase (AUC_I), and area under the curve with respect to ground (AUC_G) were computed. A rhythmic melatonin secretion over the day that remained stable across trimesters was observed among the pregnant women. There was no significant elevation in salivary melatonin levels as pregnancy advanced. In the second trimester, higher energy intake during 12:00-15:59 h and 19:00-06:59 h predicted a steeper melatonin AUC_I (β=-0.32, p = 0.034) and higher AUC_G (β = 0.26, p = 0.042), respectively. Macronutrient intake within 12:00-15:59 h was negatively associated with mean melatonin (Fat: β=-0.28, p = 0.041) and AUC_G (Carbohydrate: β=-0.37, p = 0.003; Protein: β=-0.27, p = 0.036; Fat: β=-0.32, p = 0.014). As pregnant women progressed from the second to the third trimester, a flatter AUC_I was associated with a reduced carbohydrate intake during 12:00-15:59 h (β=-0.40, p = 0.026). No significant association was detected during the third trimester. Our findings show that higher energy and macronutrient intakes particularly during 12:00-15:59 h and 19:00-06:59 h are associated with the disparities in maternal melatonin levels. Findings suggest the potential of time-based dietary approaches to entrain circadian rhythm in pregnant women.

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.

Maternal melatonin supplementation shapes gut microbiota and protects against inflammation in early life

BACKGROUND

Gut microbiota colonization is critical for immune education and nutrient metabolism. Research shows that melatonin has beneficial effects as a therapy for many diseases via modulating gut dysbiosis. However, it is unclear whether melatonin alters gut microbiota colonization in early life.

METHODS

In the experimental group (Mel), mice were intraperitoneally injected with melatonin at 10 mg/kg body weight for embryonic days 14-16 and received drinking water containing 0.4 mg/mL melatonin until 28 days postpartum. In the control group (Ctrl), mice were injected with the same volume of 2.5% ethanol in saline and provided with standard water. Two more groups were created by treating neonatal mice with 20 mg/kg lipopolysaccharide (LPS) to induce inflammation, resulting in the groups Ctrl + LPS and Mel + LPS, respectively. We examined the gut microbiota of the neonatal mice in the Ctrl and Mel group on Days 7, 14, 21, and 28 post-birth. On Day 14, melatonin and short-chain fatty acids (SCFAs) concentrations were measured in the Ctrl and Mel group and the mice were treated with LPS to be evaluated for intestinal injury and inflammatory response 15 h post treatment. According to the result of the SCFAs concentrations, some neonatal mice were intraperitoneally injected with 500 mg/kg sodium butyrate (SB) from Days 11-13, intraperitoneally injected with 20 mg/kg LPS on Day 14, and then euthanized by carbon dioxide inhalation the next morning. Intestinal injury and inflammatory responses were evaluated in the Ctrl + LPS and SB + LPS groups, respectively.

RESULTS

By Day 14, it was evident that maternal melatonin supplementation significantly increased the relative abundance of Firmicutes in the ileal [61.03 (35.35 - 76.18) % vs. 98.02 (86.61 - 99.01) %, P = 0.003] and colonic [73.88 (69.77 - 85.99) % vs. 96.16 (94.57 - 96.34) %, P = 0.04] microbiota, the concentration of melatonin (0.79 ± 0.49 ng/ml vs. 6.11 ± 3.48 ng/ml, P = 0.008) in the gut lumen, and the fecal butyric acid (12.91 ± 5.74 μg/g vs. 23.58 ± 10.71 μg/g, P = 0.026) concentration of neonatal mice. Melatonin supplementation, and sodium butyrate treatment markedly alleviated intestinal injury and decreased inflammatory factors in neonatal mice.

CONCLUSION

This study suggests that maternal melatonin supplementation can shape the gut microbiota and metabolism of offspring under normal physiological conditions and protect them against LPS-induced inflammation in early life.

Melatonin and Kidney Health: From Fetal Stage to Later Life

Melatonin, an endogenous hormone mainly released at night by the pineal gland, has multifaceted biofunctions. Emerging evidence points to melatonin having a crucial role in kidney health and disease. As the prevalence of chronic kidney disease (CKD) is still rising, a superior strategy to advance global kidney health is needed to not just treat CKD, but prevent it early on. Adult kidney disease can have its origins in early life. This review aims to evaluate the recent literature regarding melatonin's effect on kidney development, its clinical uses in the early stage of life, animal models documenting preventive applications of melatonin on offspring's kidney-related disease, and a thorough summary of therapeutic considerations concerning melatonin supplementation.

Brain washing and neural health: role of age, sleep, and the cerebrospinal fluid melatonin rhythm

The brain lacks a classic lymphatic drainage system. How it is cleansed of damaged proteins, cellular debris, and molecular by-products has remained a mystery for decades. Recent discoveries have identified a hybrid system that includes cerebrospinal fluid (CSF)-filled perivascular spaces and classic lymph vessels in the dural covering of the brain and spinal cord that functionally cooperate to remove toxic and non-functional trash from the brain. These two components functioning together are referred to as the glymphatic system. We propose that the high levels of melatonin secreted by the pineal gland directly into the CSF play a role in flushing pathological molecules such as amyloid-β peptide (Aβ) from the brain via this network. Melatonin is a sleep-promoting agent, with waste clearance from the CNS being highest especially during slow wave sleep. Melatonin is also a potent and versatile antioxidant that prevents neural accumulation of oxidatively-damaged molecules which contribute to neurological decline. Due to its feedback actions on the suprachiasmatic nucleus, CSF melatonin rhythm functions to maintain optimal circadian rhythmicity, which is also critical for preserving neurocognitive health. Melatonin levels drop dramatically in the frail aged, potentially contributing to neurological failure and dementia. Melatonin supplementation in animal models of Alzheimer's disease (AD) defers Aβ accumulation, enhances its clearance from the CNS, and prolongs animal survival. In AD patients, preliminary data show that melatonin use reduces neurobehavioral signs such as sundowning. Finally, melatonin controls the mitotic activity of neural stem cells in the subventricular zone, suggesting its involvement in neuronal renewal.