Melatonin pretreatment alleviates blast-induced oxidative stress in the hypothalamic-pituitary-gonadal axis by activating the Nrf2/HO-1 signaling pathway

The role and interaction of hypothalamic-related neurotransmitters in migraine

Migraine is a complex neurological disorder frequently associated with hypothalamic dysfunction. This brain region is essential for maintaining homeostasis due to its regulation of autonomic, endocrine, and circadian systems. While the pathophysiology of migraine remains incompletely understood, clinical features such as the cyclic nature of attacks and symptoms, including nausea, vomiting, yawning, irritability, and sensitivity to light, indicate a significant role for the hypothalamus. Further, potential triggers of migraine, such as stress and disruption to feeding habits, also impact hypothalamic mechanisms. The higher prevalence of migraine in women compared to men suggests a link to hormonal fluctuations involving estrogen, progesterone, and prolactin. These hormones interact with the hypothalamus, potentially influencing the onset and severity of migraine episodes. Additionally, the hypothalamus synthesizes neuropeptides such as orexins, neuropeptide Y, PACAP, oxytocin, and vasopressin, which are all implicated in migraine mechanisms. Understanding the interplay between the hypothalamus, sex hormones, and neuropeptides offers valuable opportunities for endogenous targeted migraine therapies. In this review we discuss hypothalamic contributions to migraine pathophysiology, highlighting the mechanisms affected by hypothalamic connections, neuropeptides, and hormones, and their role as migraine triggers, particularly focusing on factors like stress, fasting, and changes in sleep patterns.

Therapeutic Benefit of Melatonin in Choroidal Neovascularization During Aging Through the Regulation of Senescent Macrophage/Microglia Polarization

Purpose

This study aimed to investigate the age-dependent anti-angiogenic capability of melatonin in choroidal neovascularization (CNV) and to explore the underlying molecular mechanisms.

Methods

In the present study, a laser-induced CNV model was established in both young (three months of age) and old (18 months of age) mice, and the size of CNV lesions and vascular leakage was detected by morphological and imaging examination. Next, Western blot and immunostaining were used to observe the levels of M2 markers, senescence-related markers, and molecules involved in IL-10/STAT3 pathway. Additionally, colivelin was used to study the effect of IL-10/STAT3 pathway activation on the expression of M2 markers and senescence-related markers by Western blot and immunostaining. Finally, the effects of colivelin on melatonin-induced reduction of CNV size and vascular leakage in mice at different ages were assessed using morphological and imaging examination.

Results

Our results revealed that aging promoted M2 macrophage/microglia polarization, and aggravated CNV and vascular leakage. Melatonin significantly inhibited the M2 polarization of senescent macrophage/microglia and reduced the CNV area and vascular leakage. Moreover, melatonin markedly suppressed IL-10/STAT3 pathway activation in the macrophage/microglia of old mice, and STAT3 activator colivelin reversed the suppressive effect of melatonin on M2 polarization of senescent macrophage/microglia and laser-induced CNV in old mice.

Conclusions

Our data demonstrated that melatonin significantly prevented the M2 polarization of senescent macrophage/microglia by inhibiting the IL-10/STAT3 pathway, and eventually attenuated senescence-associated CNV. These findings suggested that melatonin could serve as a promising therapeutic agent to treat CNV and other age-related ocular diseases.

Melatonin: Facts, Extrapolations and Clinical Trials

Melatonin is a fascinating molecule that has captured the imagination of many scientists since its discovery in 1958. In recent times, the focus has changed from investigating its natural role as a transducer of biological time for physiological systems to hypothesized roles in virtually all clinical conditions. This goes along with the appearance of extensive literature claiming the (generally) positive benefits of high doses of melatonin in animal models and various clinical situations that would not be receptor-mediated. Based on the assumption that melatonin is safe, high doses have been administered to patients, including the elderly and children, in clinical trials. In this review, we critically review the corresponding literature, including the hypotheses that melatonin acts as a scavenger molecule, in particular in mitochondria, by trying not only to contextualize these interests but also by attempting to separate the wheat from the chaff (or the wishful thinking from the facts). We conclude that most claims remain hypotheses and that the experimental evidence used to promote them is limited and sometimes flawed. Our review will hopefully encourage clinical researchers to reflect on what melatonin can and cannot do and help move the field forward on a solid basis.

Effects of 2,2',4,4'-tetrabromodiphenyl ether (BDE-47) on reproductive and endocrine function in female zebrafish (Danio rerio)

BACKGROUND

Polybrominated diphenyl ethers (PBDEs), a group of brominated flame retardants (BFRs), were reported exist extensively in various ecological environmental. Studies have indicated that PBDEs induce reproductive toxic effects on human health, but the mechanisms remain poorly understood. In this study, the adult female zebrafish were used to investigate the effects of 2, 2', 4, 4'-tetrabromodiphenyl ether (BDE-47) on the reproductive endocrine system and its mechanism.

METHODS

Female zebrafish (AB strains) were continuously exposed to BDE-47 at the concentrations of 0, 10, 50, 100 and 500 µg/L till 21 days. The morphology of ovary were stained and evaluated with hematoxylin-eosin (H&E), and levels of sex hormones including follicle-stimulating hormone (FSH), luteinizing hormone (LH), testosterone (T) and 17β-estradiol (E₂) and the biomarkers of oxidative stress such as superoxide dismutase (SOD) and malondialdehyde (MDA), were measured via ELISA. Subsequently, the expression of genes along the hypothalamic pituitary-gonad (HPG) and oxidative stress were determined using quantitative real-time PCR (qRT-PCR).

RESULT

The results showed that exposure to high level of BDE-47 reduced the index of condition factor (CF) and gonadosomatic index (GSI). Treatment with BDE-47 impaired the normal development and structure of oocytes in zebrafish ovary. Moreover, the steroid hormone of FSH, LH, T and E₂ were significantly decreased in BDE-47 exposure group. A dose-dependent elevation in SOD activity and MDA levels were recorded. Meanwhile, the transcription level of cyp19a, cyp19b, fshβ, lhβ were up-regulated while the transcription of fshr, lhr, cyp17a, 17βhsd were down-regulated in the gonad of female adult zebrafish.

CONCLUSION

Exposure to BDE-47 have detrimental impact on the development of ovary, decreasing sex hormone levels, inducing oxidative damage as well as altering HPG axis-related genes.

Melatonin pretreatment on exosomes: Heterogeneity, therapeutic effects, and usage

The therapeutic outcomes of exosome-based therapies have greatly exceeded initial expectations in many clinically intractable diseases due to the safety, low toxicity, and immunogenicity of exosomes, but the production of the exosomes is a bottleneck for wide use. To increase the yield of the exosomes, various solutions have been tried, such as hypoxia, extracellular acidic pH, etc. With a limited number of cells or exosomes, an alternative approach has been developed to improve the efficacy of exosomes through cell pretreatment recently. Melatonin is synthesized from tryptophan and secreted in the pineal gland, presenting a protective effect in pathological conditions. As a new pretreatment method, melatonin can effectively enhance the antioxidant, anti-inflammatory, and anti-apoptotic function of exosomes in chronic kidney disease, diabetic wound healing, and ischemia-reperfusion treatments. However, the current use of melatonin pretreatment varies widely. Here, we discuss the effects of melatonin pretreatment on the heterogeneity of exosomes based on the role of melatonin and further speculate on the possible mechanisms. Finally, the therapeutic use of exosomes and the usage of melatonin pretreatment are described.

Impact of Low-Dose Melatonin Supplementation on Testosterone Levels in U.S. Adult Males

OBJECTIVE

Amidst the rapid rise in melatonin supplementation, decreased testosterone levels amongst males in recent decades, and the unclear association between melatonin and the hypogonadal-pituitary-gland (HPG) axis, this study aimed to further examine the association of melatonin use and impact on testosterone levels among men in a nationally representative sample.

METHODS

U.S. men over the age of 18 surveyed from 2011-2016 via the National Health and Nutrition Examination Survey (NHANES) without missing demographic or pertinent health information were included in the analysis. A total testosterone (TT) level of less than 300 ng/dL was considered low. An average daily dose (ADD) was calculated to quantify participants' exposure to melatonin supplementation in the past 30 days.

RESULTS

Analysis included 7,656 participants after selection criteria. Median age of participants was 47 [31-63] years old; median TT level was 389.9 [289 - 513.9] ng/dL. Melatonin intake was reported in 51 (0.7%) individuals with an ADD of 1 [0.4 - 3] mg/day. We found no association between melatonin intake in the past 30 days and low TT levels (OR = 0.958, 95% CI: 0.496 -1.850; p=0.898). As expected, increasing BMI (OR = 1.133, 95% CI: 1.122 - 1.144; p < 0.001) and older age (OR = 1.019, 95% CI: 1.016 - 1.022; p < 0.001) were associated with low TT levels.

CONCLUSION

Predominantly low-dose melatonin supplementation was not associated with low TT levels. Future studies are needed to better quantify the relationship between melatonin intake and low TT levels, especially in the setting of supratherapeutic doses and prolonged periods of exposure.

Pu-erh Tea Restored Circadian Rhythm Disruption by Regulating Tryptophan Metabolism

Pu-erh tea is a healthy beverage rich in phytochemicals, and its effect on the risk of inducing circadian rhythm disorders (CRD) is unclear. In this study, healthy mice were given water or 0.25% (w/v) Pu-erh tea for 7 weeks, followed by a 40 day disruption of the light/dark cycle. CRD caused dysregulation of neurotransmitter secretion and clock gene oscillations, intestinal inflammation, and disruption of intestinal microbes and metabolites. Pu-erh tea boosted the indole and 5-hydroxytryptamine pathways of tryptophan metabolism via the gut-liver-brain axis. Furthermore, its metabolites (e.g., IAA, Indole, 5-HT) enhanced hepatic glycolipid metabolism and down-regulated intestinal oxidative stress by improving the brain hormone release. Tryptophan metabolites and bile acids also promoted liver lipid metabolism and inhibited intestinal inflammation (MyD88/NF-κB) via the enterohepatic circulation. Collectively, 0.25% (w/v) Pu-erh tea has the potential to prevent CRD by promoting indole and 5-HT pathways of tryptophan metabolism and signaling interactions in the gut-liver-brain axis.

Melatonin attenuates LPS-induced pyroptosis in acute lung injury by inhibiting NLRP3-GSDMD pathway via activating Nrf2/HO-1 signaling axis

Acute lung injury (ALI)/ acute respiratory distress syndrome (ARDS) is featured by intensive inflammatory responses and oxidative stress, which lead to cytokine storms and pyroptosis. Here, we aimed to investigate whether melatonin was capable of alleviating LPS-induced ALI via activating the nuclear factor erythroid 2-related factor 2/heme oxygenase 1 (Nrf2/HO-1) signaling axis and inhibiting pyroptosis. Mice were injected with melatonin (30 mg/kg) intraperitoneally for consecutive five days before LPS instillation intratracheally, and human alveolar epithelial cell (AECⅡ) A549 cell lines and murine macrophages Raw264.7 cell lines were pretreated with melatonin (400 μM) before LPS (10 μg/ml) stimulation. The result demonstrated that LPS induced obvious lung injury characterized by alveolar damage, neutrophil infiltration and lung edema as well as the reduction of the survival rate of mice, which were totally reversed by melatonin pretreatment. Mechanistically, melatonin pretreatment activated nuclear factor erythroid2-related factor (Nrf) 2 signaling, subsequently, drove antioxidant pathways including significant increases in the expression of Nrf2, HO-1, NQO1, Mn-SOD and Catalase in vivo and in vitro. Simultaneously, melatonin inhibited ROS and MDA overproduction, iNOS expression as well as TNF-α and IL-1β expression and release. Furthermore, melatonin inhibited LPS-induced pyroptosis by reversing the overexpression of NLRP3, Caspase-1, IL-1β, IL-18 and GSDMD-N, as well as LDH release and TUNEL-positive cells in A549 cells and Raw264.7 cells. Overall, the current study suggests that melatonin exerts protective roles on LPS-induced ALI and pyroptosis by inhibiting NLRP3-GSDMD pathway via activating Nrf2/HO-1 signaling axis.

Multi-level hypothalamic neuromodulation of self-regulation and cognition in preterm infants: Towards a control systems model

Preterm infants, age-corrected for prematurity, score on average, 10 points lower on IQ tests than full-term infants tested at comparable ages. This review focuses on the potential contribution of the hypothalamus to cognitive neuro-regulatory development in preterm infants through its bidirectional neural connections with the prefrontal cortex and its neuroendocrine activity. It aims to clarify the central role of the hypothalamus in preterm high stress situations and in influencing cognitive development via its connectivity to the cerebral cortex. The review further evaluates epigenomic sensitivity to environmental inputs. Recent results suggest that an optimal range of DNA methylations (via a continuous process of decreasing levels of receptor methylations that are too high, and increasing levels that are too low) appears necessary in order to reach an adaptive level of receptor availability. Several studies have demonstrated amelioration of preterm infants' stress while in the Newborn Intensive Care Unit (NICUs) and following discharge. The authors postulate that feedback mechanisms and correction signals are the basis for a hypothalamic homeostatic modulating function, a "hypothalamic resistance response", which may account for the stress reduction brought about by in- and post-NICU early interventions and their results of promoting self-regulation and cognition.

Butyric Acid Protects Against Renal Ischemia-Reperfusion Injury by Adjusting the Treg/Th17 Balance via HO-1/p-STAT3 Signaling

Immune regulation plays a vital role in ischemia-reperfusion injury (IRI). Butyric acid (BA) has immunomodulatory effects in many diseases, but its immunomodulatory effects during renal IRI are still unclear. Our research shows that BA protected against IRI and significantly improved renal IRI in vivo. In vitro studies showed that BA inhibits Th17 cell differentiation and induces Treg cell differentiation. Mechanism studies have shown that heme oxygenase 1 (HO-1)/STAT3 signaling pathway was involved in the inhibitory effect of BA on Th17 cell differentiation. HO-1 inhibitors can significantly rescue the BA-mediated inhibition of Th17 cell differentiation. We confirmed that BA promotes the differentiation of Th17 cells into Treg cells by regulating the pathway and reduces renal IRI.