Effects of long-term light, darkness and oral administration of melatonin on serum levels of melatonin

Recent Advances in Nanomaterials Based Optical Sensors for the Detection of Melatonin and Serotonin

In this review paper we discussed the detection of melatonin and serotonin by using various optical methods. Melatonin and serotonin are very necessary body hormones these are also called neuroregulatory hormones secreted by pineal gland in brain by pinealocytes and shape of pineal gland is cone like. Sensitive detection of melatonin and serotonin in pharmacological samples and human serum is crucial for human beings, lots of research publications available in literature for melatonin and serotonin and we overviewed these papers. We have deeply reviewed many research papers where sensitively sensing of melatonin and serotonin occurs, by using of various interfering agents and nanomaterials. This review aims presenting colorimetry, fluorometry and spectrophotometric detection of melatonin (MEL) and serotonin (SER) by using different metal oxides, carbon nanomaterials (nanosheets, nanorods, nanofibers) and many other agents. Nanomaterials typically possess favourable optical, electrical and mechanical characteristics, they provide up new avenues for enhancing the efficacy of sensors. It is crucial to provide an optical sensors platform that is dependable, sensitive and low price. The development of sensors and biosensors to use nanomaterials for neurotransmitters has advanced significantly in recent years. There are currently many developing biomarkers in biological fluids, and bionanomaterial-based biosensor systems, as well as clinical and pharmacological settings, have garnered significant interest. Biomarkers have been found using optical devices in a quick, selective and sensitive manner. Our aim is to compile all the data that already published on MEL, SER sensing and comparison of each method, we mainly focused on principle, observations, sensitivity, selectivity, limit of detection, mechanism behind the reaction, effect of temperature, pH and concentration. In the last of this paper, we discuss some challenges of these methods and future projects.

Shortened Daily Photoperiod Alleviates Anxiety-like Behaviour by Antioxidant Effect and Changes Serum Fatty Acid Profile in Diabetic Rats

The aim of our study was to investigate the effects of a shortened daily photoperiod on anxiety-like behaviour, brain oxidative stress, lipid status and fatty acid composition of serum lipids in a streptozotocin (STZ)-induced model of diabetes mellitus in rats. Male Wistar rats were divided into the following groups: first group-control group (C_12/12); second group-diabetic group (DM_12/12; 100 mg/kg STZ); third group-control group exposed to a light/dark cycle 6/18 h (C_6/18); fourth group-diabetic group exposed to a light/dark cycle 6/18 h (DM_6/18). Anxiety-like behaviour was tested three weeks following STZ injection by elevated plus maze (EPM) and open-field test (OFT). Oxidative stress parameters were measured in the cortex, hippocampus and thalamus, while lipid status and fatty acid methyl esters (FAMEs) were measured in the serum. Both EPM and OFT showed a lower degree of anxiety-like behaviour in the DM_6/18 vs. DM_12/12 group. Lipid peroxidation in the cortex, hippocampus and thalamus was significantly lower in the DM_6/18 vs. DM_12/12 group (p < 0.05), associated with an increased level of antioxidant enzymes and protein thiols in the cortex and thalamus. In the DM_6/18 group, oleic, vaccenic, dihomo-γ-linolenic and docosahexaenoic acid concentrations were significantly higher in comparison to the DM_12/12 group. A shortened daily photoperiod alleviates anxiety-like behaviour in diabetic rats by reduced lipid peroxidation and changes in the serum fatty acids profile.

Inhibiting nighttime melatonin and boosting cortisol increase patrolling monocytes, phagocytosis, and myelination in a murine model of multiple sclerosis

Conflicting results on melatonin synthesis in multiple sclerosis (MS) have been reported due to variabilities in patient lifestyles, which are not considered when supplementing melatonin. Since melatonin acts through its receptors, we identified melatonin receptors in oligodendrocytes (OLs) in the corpus callosum, where demyelination occurs; the subventricular zone, where neural stem/progenitor cells (NSPCs) are located; and the choroid plexus, which functions as a blood-cerebrospinal fluid barrier. Moreover, using chimeric mice, resident macrophages were found to express melatonin receptors, whereas bone marrow-derived macrophages lost this expression in the demyelinated brain. Next, we showed that cuprizone-fed mice, which is an MS model, tended to have increased melatonin levels. While we used different approaches to alter the circadian rhythm of melatonin and cortisol, only the constant light approach increased NSPC proliferation and differentiation to oligodendrocyte precursor cells (OPCs), OPCs maturation to OLs and recruitment to the site of demyelination, the number of patrolling monocytes, and phagocytosis. In contrast, constant darkness and exogenous melatonin exacerbated these events and amplified monocyte infiltration. Therefore, melatonin should not be considered a universal remedy, as is currently claimed. Our data emphasize the importance of monitoring melatonin/cortisol oscillations in each MS patient by considering diet and lifestyle to avoid melatonin overdose.

Role of chronotype in dietary intake, meal timing, and obesity: a systematic review

CONTEXT

Recent studies show that dietary habits and obesity seem to be influenced by chronotype, which reflects an individual's preference for the timing of sleeping, eating, and activity in a 24-hour period.

OBJECTIVE

This review aimed to analyze the association of chronotype with dietary habits, namely energy and macronutrient intakes, meal timing, and eating patterns, as well as with obesity.

DATA SOURCES

PubMed/MEDLINE, LILACS, and Google Scholar databases were searched between 2004 and 2020. Study selection was performed by 2 authors independently; disagreements on eligibility of articles were resolved by a third author. After assessment of 12 060 abstracts, 43 studies (21 articles on obesity; 13 on food consumption, meal timing, and eating patterns; and 9 that addressed both obesity and dietary behavior) were included.

DATA EXTRACTION

A standard form was used to extract study design, country, number of participants, method of chronotype determination, and main findings.

DATA ANALYSIS

Approximately 95% of included studies showed an association between eveningness and at least 1 unhealthy eating habit. Morningness was associated with regular consumption of fresh and minimally processed foods. In addition, about 47% of studies showed a higher association between late types and obesity.

CONCLUSION

Late types are more likely to present unhealthy eating habits, such as eating late at night, skipping breakfast often, and eating processed/ultraprocessed foods, while early types are more likely to have healthy and protective habits, such as eating early and eating predominantly fresh/minimally processed foods. Intermediate types tend to have a pattern of health and eating more similar to early types than to late types. Late types are also more likely to present higher weight and body mass index than early or intermediate types.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO registration no. CRD42021256078.

Behavioral and cardiovascular effects of a single dose of gabapentin or melatonin in cats: a randomized, double-blind, placebo-controlled trial

OBJECTIVES

The aim of this study was to verify whether a single oral dose of gabapentin (100 mg) or melatonin (3 mg) given 60 mins before a cardiac evaluation would reduce anxiety without interfering with heart rate (HR), systemic blood pressure (SBP), electrocardiogram (ECG) and echocardiographic indexes.

METHODS

Seventy-five client-owned healthy cats underwent two sets of cardiac assessments 60 mins apart, randomly divided into gabapentin, melatonin and placebo groups. The interval between treatment and the second ECG and SBP measurement was 60 mins, and 70 mins for echocardiography. A compliance score (CS) classified the behavior, focusing on the ease of handling.

RESULTS

Most variables did not change between the examinations. The placebo group showed more significant changes (SBP, tricuspid annular plane systolic excursion, HR during echocardiography, aortic flow velocity, S' wave from lateral mitral annulus), but they were not considered to be hemodynamically relevant. Gabapentin and melatonin significantly increased the cats' compliance without interfering with cardiac assessment. Eight cats presented with mild sedation, seven after gabapentin and one after melatonin. No major side effects were observed.

CONCLUSIONS AND RELEVANCE

Gabapentin tranquilized the cats when it was given 60 mins prior to ECG and SBP measurement, and 70 mins prior to echocardiography, without interfering with systolic echocardiographic indexes. Melatonin also decreased the CS, but without sedation in most cases. The waiting period may have relaxed the cats in the placebo group, resulting in lower SBP measurements. However, this tranquility did not last as some echocardiographic changes signaled a sympathetic predominance.

Long-term environmental exposure of darkness induces hyperandrogenism in PCOS via melatonin receptor 1A and aromatase reduction

Polycystic ovary syndrome (PCOS) is a common and complex disorder impairing female fertility, yet its etiology remains elusive. It is reported that circadian rhythm disruption might play a crucial role in PCOS pathologic progression. Here, in this research, we investigated the effect of environmental long-term circadian rhythm dysfunction and clarified its pathogenic mechanism in the development of PCOS, which might provide the targeted clinical strategies to patients with PCOS. Female SD rats were used to construct a circadian rhythm misalignment model with constant darkness (12/12-h dark/dark cycle), and the control group was kept under normal circadian rhythm exposure (12/12-h light/dark cycle) for 8 weeks. We measured their reproductive, endocrinal, and metabolic profiles at different zeitgeber times (ZTs). Different rescue methods, including melatonin receptor agonist and normal circadian rhythm restoration, and in vitro experiments on the KGN cell line were performed. We found that long-term darkness caused PCOS-like reproductive abnormalities, including estrous cycle disorder, polycystic ovaries, LH elevation, hyperandrogenism, and glucose intolerance. In addition, the expression of melatonin receptor 1A (Mtnr1a) in ovarian granulosa cells significantly decreased in the darkness group. Normal light/dark cycle and melatonin receptor agonist application relieved hyperandrogenism of darkness-treated rats. In vitro experiments demonstrated that decreased MTNR1A inhibited androgen receptor (AR) and CYP19A1 expression, and AR acted as an essential downstream factor of MTNR1A in modulating aromatase abundance. Overall, our finding demonstrates the significant influence of circadian rhythms on PCOS occurrence, suggests that MTNR1A and AR play vital roles in pathological progression of hyperandrogenism, and broadens current treatment strategies for PCOS in clinical practice.

Study of the effect of heavy metals and differences of light / dark cycle in the melatonin hormone protein Clock and growth of Neurospora crassa fungi

It was using Neurospora crassa as a model organism to study the biological clock. Due to its use for more than 50 years in the circadian rhythm Study, this biological cycle has been studied by growing it on a Vogel's medium with a constant temperature and different light cycles (continuous light, light to dark, continuous darkness) with different concentrations of heavy metals (Lead Nitrate II, Zinc sulfate, Cadmium chloride, iron chloride III). It was also Measured protein CLOCK and hormone Melatonin By using Elisa Kit. Neurospora crassa was cultured in a thin layer of Vogel's medium using growth tubes (tube race) which grow in one direction only and are distributed by forming conida bands on the medium surface; each band represents one cycle circadian. However, examining Nerospora conidia on growth tubes is a simple but powerful tool for studying the circadian clock and detecting the effect of heavy metals and light on it. At the same time, the results indicated an apparent decrease of CLOCK protein at continuous light compared to light/dark for all treatments. It also recorded a rise in melatonin concentration in continuous darkness and decreased with continuous lighting. The results of the growth tubes also indicated a decrease in growth at continuous light compared to light/dark. Heavy metals also affected Neurospora crassa, as it had the highest inhibition when using lead nitrate II compared to iron chloride III. The study aimed to investigate the effect of heavy metals and differences in light and darkness on the biological clock of the fungus Neurospora crassa.Conclusion the effect on the biological clock disturbances of Neurospora crassa Keywords. Neurospora crassa, Melatonin hormone, Clock protein, Heavy metals, light, dark.

Electroacupuncture Ameliorates Cognitive Impairment Through the Inhibition of NLRP3 Inflammasome Activation by Regulating Melatonin-Mediated Mitophagy in Stroke Rats

Previous studies found that electroacupuncture (EA) at the Shenting (DU24) and Baihui (DU20) acupoints alleviates cognitive impairment in cerebral ischemia-reperfusion (I/R) injury rats. Nonetheless, the mechanisms of the anti-inflammatory effects of EA are unclear. Cerebral I/R injury was induced in rats by middle cerebral artery occlusion (MCAO). Following I/R injury, the rats underwent EA therapy at the Shenting (DU24) and Baihui (DU20) acupoints for seven successive days. The Morris water maze test, magnetic resonance imaging (MRI) and molecular biology assays were utilized to assess the establishment of the rat stroke model with cognitive impairment and the therapeutic effect of EA. EA treatment of rats subjected to MCAO showed a significant reduction in infarct volumes accompanied by cognitive recovery, as observed in Morris water maze test outcomes. The possible mechanisms by which EA treatment attenuates cognitive impairment are by regulating endogenous melatonin secretion through aralkylamine N-acetyltransferase gene (AANAT, a rate-limiting enzyme of melatonin) synthesis in the pineal gland in stroke rats. Simultaneously, through melatonin regulation, EA exerts neuroprotective effects by upregulating mitophagy-associated proteins and suppressing reactive oxygen species (ROS)-induced NLRP3 inflammasome activation after I/R injury. However, melatonin receptor inhibitor (luzindole) treatment reversed these changes. The findings from this research suggested that EA ameliorates cognitive impairment through the inhibition of NLRP3 inflammasome activation by regulating melatonin-mediated mitophagy in stroke rats.

Melatonin stabilizes age-dependent alterations in erythrocyte membrane induced by 'Artificial Light at Night' in a chronodisrupted model of rat

Growing evidence has shown that Artificial light at night (ALAN) is one of the threatening risk factors which disrupt circadian homeodynamics of cellular processes. The chronobiological role of melatonin seems to represent an important aspect of its contribution to healthy aging. In the present study, we examined the age dependent effect of melatonin on erythrocyte membrane transporters and oxidative stress biomarkers against ALAN to understand the degree of photo-oxidative damage in chronodisrupted rat model. Young (3 months) and old (24 months) male Wistar rats were subdivided in the following four young groups (n = 4) ; (i) control (ii) melatonin (10 mg/kg) (iii) ALAN (500 lx) (iv) ALAN (500 lx) + melatonin (10 mg/kg) and four old groups (n = 4); (v) control (vi) melatonin (10 mg/kg) (vii) ALAN (500 lx) (viii) ALAN (500 lx) + melatonin (10 mg/kg) to the experimental conditions for 10 days. Our findings demonstrated that ALAN significantly enhanced erythrocyte membrane lipid hydroperoxides (LHPs), protein carbonyl (PCO) while reduced total thiol (T-SH), and sialic acid (SA) level with higher amplitude in old ALAN group is restored by exogenous supplementation of melatonin. Activity of membrane transporters, sodium potassium ATPase (NKA) and plasma membrane calcium ion ATPase (PMCA) is significantly reduced meanwhile sodium hydrogen exchanger (NHE) activity is enhanced under the influence of ALAN with higher extent in old groups is effectively ameliorated by melatonin treatment. Further melatonin reduced osmotic fragility of erythrocyte in both young and old rats. It has been concluded from results that ALAN provoked redox insult and disrupt transporters activity more prominently in erythrocyte membrane of aged groups. Exogenous supplementation of melatonin is one of the possible therapeutic approaches to reinforce circadian modulations against ALAN in aged populations.

A Sensitive Electrochemical Sensor Based on Sonogel-Carbon Material Enriched with Gold Nanoparticles for Melatonin Determination

In this work, the development of an electrochemical sensor for melatonin determination is presented. The sensor was based on Sonogel-Carbon electrode material (SNGCE) and Au nanoparticles (AuNPs). The low-cost and environmentally friendly SNGCE material was prepared by the ultrasound-assisted sonogel method. AuNPs were prepared by a chemical route and narrow size distribution was obtained. The electrochemical characterization of the SNGCE/AuNP sensor was carried out by cyclic voltammetry in the presence of a redox probe. The analytical performance of the SNGCE/AuNP sensor in terms of linear response range, repeatability, selectivity, and limit of detection was investigated. The optimized SNGCE/AuNP sensor displayed a low detection limit of 8.4 nM melatonin in synthetic samples assessed by means of the amperometry technique. The potential use of the proposed sensor in real sample analysis and the anti-matrix capability were assessed by a recovery study of melatonin detection in human peripheral blood serum with good accuracy.

Age-dependent effect of continuous 'artificial light at night' on circadian rhythm in male rats: neuroprotective role of melatonin

Circadian disruption due to artificial light at night (ALAN) is an alarming threat to modern society. In the present study we evaluated the protective effect of melatonin on age dependent redox insults and neurochemical deficits induced by ALAN in the brain of chronodisrupted rat model. Young (3 months) and old (22 months) male Wistar rats were exposed to ALAN along with melatonin supplementation (10 mg Kg^-1, oral) for 10 days. Results demonstrated significant increment in the pro-oxidant biomarkers: reactive oxygen species, lipid hydroperoxidation, protein carbonyl, nitric oxide while suppression in the total thiol, ferric reducing antioxidant potential level, superoxide dismutase and catalase activities in the brain of ALAN exposed groups with higher amplitude in aged rats. Further these oxidative modifications were protected by subsequent administration of melatonin. Mitochondrial complexes (C-I to C-IV) activity was significantly altered in young and old ALAN exposed groups with melatonin showing protective effect. Histopathological analysis show dense cytosolic staining and neuronal degeneration in cerebral cortex and different hippocampus regions with greater extent in old ALAN rats effectively moderated by melatonin supplementation. RT-PCR data analysis revealed melatonin effectively downregulated neuroinflammatory (IL-6, TNF α) and neurodegenerative marker (Ngb) while upregulating the aging (Sirt 1) gene expression in both young and old melatonin supplemented ALAN exposed groups. Our results may help in understanding the degree of ALAN induced photo-oxidative damage in neuronal redox homeostasis during aging. We also show that melatonin supplementation might provide a basis for amelioration of oxidative disturbances to improve circadian entrainment in aged populations.

Melatonin exerts neuroprotection in a chronodisrupted rat model through reduction in oxidative stress and modulation of autophagy

Circadian disruption due to artificial light affects cellular redox homeostasis and may lead to neurodegenerative diseases. The aim of the present study was to investigate the effect of continuous light exposure (CLE) and continuous dark exposure (CDE) along with melatonin supplementation on neuronal redox status, mitochondrial complexes, membrane bound transporters, inflammation, autophagy and neurodegeneration in chronodisrupted model of rat. In the study artificial light of white LED bulb with 500 lux intensity was used. Melatonin (10 mg/kg b.w., orally) was supplemented to control and CLE groups for 10 days. Standard protocols were employed to measure pro-oxidants, non-enzymatic antioxidants, and mitochondrial complexes in brain tissues. Membrane-bound ion transporter activities were evaluated in the crude synaptosomes. Gene expression analysis was performed to assess the expression of inflammatory, autophagy and neuronal marker genes. Histopathological changes in cerebral cortex and different hippocampus regions of the brain were studied. Melatonin exerted a significant normalization of redox status biomarkers in brain tissue. Further melatonin restored the activities of mitochondrial complexes and synaptosomal membrane bound ion transporters. RT-PCR data revealed that melatonin downregulated the expression of inflammatory (TNF-α, IL-6) autophagy (Atg-3, Beclin-1) and neurodegenerative genes (Ngb and NSE) in CLE group. Melatonin also preserved the histology architecture in cerebral cortex and hippocampus. Our results indicate that melatonin exerts a potent neuroprotective effect through reduction of oxidative stress, inflammation and autophagy. Melatonin supplementation might be a promising neurotherapeutic in the treatment neurodegenerative disorders caused by circadian disturbances.

Therapeutic effects of melatonin on an ovalbumin-induced allergic rhinitis model in rats

OBJECTIVE

We aimed to investigate the therapeutic effects of melatonin in an experimental AR model.

METHODS

Thirty-two Wistar rats were randomised into four groups (n = 8 each). The experimental AR model was established in the saline (SF), ethanol, and melatonin groups via intraperitoneal (i.p.) injections and intranasal application of ovalbumin. The SF, ethanol, and melatonin groups received daily i.p. saline, 2% ethanol dissolved in saline, and 10 mg/kg melatonin dissolved in 2% ethanol and saline. The control group received the same amount of i.p. and intranasal saline. Total nasal symptom scores were recorded in all rats on days 1 (baseline), 15, 20, 25, and 30. Serum ovalbumin-specific IgE, IL-13, and melatonin levels were measured on days 1 (baseline), 15, and 30. The nasal mucosa of all rats was scored histopathologically.

RESULTS

The total nasal symptom scores and serum ovalbumin-specific IgE values of the SF, ethanol, and melatonin groups were significantly higher on day 15 than those of the control group. On day 30, the scores and serum ovalbumin-specific IgE values of the melatonin group were similar to those of the control, whereas the SF and ethanol groups had statistically higher scores. The histological scores of the SF and ethanol groups were significantly higher than those of the control and melatonin groups, but no significant difference was found between the melatonin and control groups.

CONCLUSION

Melatonin reduced total nasal symptom scores and serum ovalbumin-specific IgE levels and improved histological inflammation parameters in the ovalbumin-induced rat experimental AR model.

Effect of Long-Term Light Deprivation on α-Tocopherol Content in Rats during Ontogeny

We studied the effect of long-term light deprivation which began at different stages of ontogeny on the content of α-tocopherol in rats during the first 3 months of postnatal development. In the offspring postnatally exposed to constant darkness, the level of α-tocopherol in the liver, kidneys, heart, skeletal muscles, and lungs was significantly decreased at the early stages of postnatal ontogeny (2 weeks and 1 month). In rats kept under constant darkness after birth, the content of α-tocopherol in the lungs was also reduced at the age of 1 month. The modulating effect of light deprivation on the level of α-tocopherol can be associated both with the impact of disturbed circadian rhythms and with increased content of melatonin in the body.

Age-dependent altered redox homeostasis in the chronodisrupted rat model and moderation by melatonin administration

Circadian disruption or chronodisruption (CD) occurs when day-night cycles and other internal rhythms are not adjusted to environmental light-dark regimens and are unable to synchronize among each other. Artificial light-induced oxidative stress is a major concern as the circadian physiology of the cell is chronically altered due to suppression of the time-keeping hormone, melatonin. The relationship between age-related impaired redox status and disrupted circadian rhythms is still not fully understood. The present study evaluated the effect of artificial light at night (ALAN) with respect to aging and role of melatonin supplementation. This study was conducted on young (3 months) and old (24 months) male Wistar rats subdivided into four groups control (C), melatonin treated (MLT), artificial light at night (ALAN), and ALAN+MLT group. Pronounced changes were observed in the old compared to the young rats. Reactive oxygen species (ROS), malondialdehyde (MDA), plasma membrane redox system (PMRS), protein carbonyl (PCO), and sialic acid (SA) were significantly (p ≤ 0.05) increased, while ferric reducing ability of plasma (FRAP) and reduced glutathione (GSH) were significantly (p ≤ 0.05) suppressed in light-exposed young and old animals compared to their age-matched controls. Advanced oxidation protein products (AOPP) increased non-significantly in young rats of the ALAN group; however, significant (p ≤ 0.05) changes were observed in the old rats of the ALAN group compared to their respective controls. Advanced glycation end products (AGEs) increased and acetylcholinesterase (AChE) activity decreased, significantly (p ≤ 0.05) in young animals of the ALAN group, while nonsignificant changes of both parameters were recorded in the old animals of the ALAN groups compared with their age-matched controls. Melatonin supplementation resulted in maintenance of the normal redox homeostasis in both young and old animal groups. Our study suggests that aged rats are more susceptible to altered photoperiod as their circadian redox homeostasis is under stress subsequent to ALAN. Melatonin supplementation could be a promising means of alleviating age-related circadian disturbances, especially in light-polluted areas.

Altered circadian clock as a novel therapeutic target for constant darkness-induced insulin resistance and hyperandrogenism of polycystic ovary syndrome

The mechanisms underlying metabolic and reproductive dysfunction caused by arrhythmic circadian clock and their involvement in polycystic ovary syndrome (PCOS) are not understood. Here, we addressed this issue using rats with constant light or darkness exposure for 8 weeks and human leukocytes and serum of PCOS and non-PCOS patients. Additionally, we utilized HepG2 cells and KGN cells to verify the molecular mechanisms. The arrhythmic expressions of circadian clock genes due to constant darkness induced the metabolic and reproductive hallmarks of PCOS in rats. After exposure to constant darkness, decreased brain and muscle ARNT-like protein 1 (BMAL1) promoted insulin resistance via glucose transporter 4 (GLUT4), and decreased period (PER) 1 and PER2 promoted androgen excess via insulin-like growth factor-binding protein 4 (IGFBP4) and sex hormone binding globulin (SHBG) in the liver. Hyperinsulinemia and hyperandrogenism shared a bidirectional link promoting aberrant expression of circadian genes and inducing apoptosis of ovarian granulosa cells. Notably, the altered expressions of circadian clock genes in darkness-treated rats matched those of PCOS patients. Furthermore, melatonin treatment relieved the hyperinsulinemia and hyperandrogenism of darkness-treated rats via BMAL1, PER1, and PER2. Restoring normal light/dark exposure for 2 weeks reversed these conditions via BMAL1. In conclusion, our findings elucidated the critical function of circadian clock genes, especially BMAL1, PER1, and PER2 in PCOS, which might aid the development of feasible preventive and therapeutic strategies for PCOS in women with biorhythm disorder.

The association between sleep chronotype and obesity among black and white participants of the Bogalusa Heart Study

Research indicates that sleep duration and quality are inter-related factors that contribute to obesity, but few studies have focused on sleep chronotype, representing an individual's circadian proclivity, nor assessed these factors in racially diverse middle-aged samples. We examined the associations between chronotype and obesity among black and white men and women participating in the Bogalusa Heart Study (BHS).Body mass index (BMI) and sleep data were available for 1,197 middle-aged men and women (mean age 48.2 ± 5.3 years) who participated in the BHS 2013-2016. Based on the reduced Morningness-Eveningness Questionnaire's cutoff values for chronotypes, we combined 'definitely morning' and 'moderately morning' types into 'morning' type, 'definitely evening' and 'moderately evening' types into 'evening' type and kept those who were "neither" type in a separate group. We used 'morning' type as the referent group. Obesity was defined as a BMI ≥ 30. Multivariable logistic regression models were used to examine associations adjusting for sex, age, education, smoking, alcohol use and drug use, depression, shift work, physical activity and sleep duration.Evening chronotype, reported by 11.1% of participants, was associated with obesity after multi-variable adjustment, including shift work, physical activity and sleep duration (OR 1.67, 95% CI: 1.08-2.56). However, once stratified by race (black/white), this association was found only among white participants (OR = 1.91, 95% CI = 1.12-3.25) after full adjustment.In our biracial, community-based population, evening chronotype was independently associated with obesity, specifically among white participants. Further research is needed to identify behavioral, endocrine, nutritional and genetic pathways which underlie these associations.

Elevated Serum Melatonin under Constant Darkness Enhances Neural Repair in Spinal Cord Injury through Regulation of Circadian Clock Proteins Expression

We investigated the effects of environmental lighting conditions regulating endogenous melatonin production on neural repair, following experimental spinal cord injury (SCI). Rats were divided into three groups randomly: the SCI + L/D (12/12-h light/dark), SCI + LL (24-h constant light), and SCI + DD (24-h constant dark) groups. Controlled light/dark cycle was pre-applied 2 weeks before induction of spinal cord injury. There was a significant increase in motor recovery as well as body weight from postoperative day (POD) 7 under constant darkness. However, spontaneous elevation of endogenous melatonin in cerebrospinal fluid was seen at POD 3 in all of the SCI rats, which was enhanced in SCI + DD group. Augmented melatonin concentration under constant dark condition resulted in facilitation of neuronal differentiation as well as inhibition of primary cell death. In the rostrocaudal region, elevated endogenous melatonin concentration promoted neural remodeling in acute phase including oligodendrogenesis, excitatory synaptic formation, and axonal outgrowth. The changes were mediated via NAS-TrkB-AKT/ERK signal transduction co-regulated by the circadian clock mechanism, leading to rapid motor recovery. In contrast, exposure to constant light exacerbated the inflammatory responses and neuroglial loss. These results suggest that light/dark control in the acute phase might be a considerable environmental factor for a favorable prognosis after SCI.

Helicobacter pylori's road to colonization

In this issue of the Biomedical Journal we learn about the virulence factors that have made Helicobacter pylori such a successful pathogen. We also highlight some in vitro findings that may shed light on epithelial-mesenchymal transition that occurs during renal fibrosis. This issue also includes the findings of clinical trials testing the effectiveness of drugs to limit nausea in chemotherapy patients and the symptoms of alcohol withdrawal syndrome.