Impact of light/dark cycle patterns on oxidative stress in an adriamycin-induced nephropathy model in rats

Circadian light/dark cycle reversal exacerbates the progression of chronic kidney disease in mice

Circadian disruption such as shift work, jet lag, has gradually become a global health issue and is closely associated with various metabolic disorders. The influence and mechanism of circadian disruption on renal injury in chronic kidney disease (CKD) remains inadequately understood. Here, we evaluated the impact of environmental light disruption on the progression of chronic renal injury in CKD mice. By using two abnormal light exposure models to induce circadian disruption, we found that circadian disruption induced by weekly light/dark cycle reversal (LDDL) significantly exacerbated renal dysfunction, accelerated renal injury, and promoted renal fibrosis in mice with 5/6 nephrectomy and unilateral ureteral obstruction (UUO). Mechanistically, RNA-seq analysis revealed significant immune and metabolic disorder in the LDDL-conditioned CKD kidneys. Consistently, renal content of ATP was decreased and ROS production was increased in the kidney tissues of the LDDL-challenged CKD mice. Untargeted metabolomics revealed a significant buildup of lipids in the kidney affected by LDDL. Notably, the level of β-NMN, a crucial intermediate in the NAD+ pathway, was found to be particularly reduced. Moreover, we demonstrated that both β-NMN and melatonin administration could significantly rescue the light-disruption associated kidney dysfunction. In conclusion, environmental circadian disruption may exacerbate chronic kidney injury by facilitating inflammatory responses and disturbing metabolic homeostasis. β-NMN and melatonin treatments may hold potential as promising approaches for preventing and treating light-disruption associated CKD.

Rhythm and ROS: Hepatic Chronotherapeutic Features of Grape Seed Proanthocyanidin Extract Treatment in Cafeteria Diet-Fed Rats

Polyphenols play a key role in the modulation of circadian rhythms, while the cafeteria diet (CAF) is able to perturb the hepatic biological rhythm and induce important ROS production. Consequently, we aimed to elucidate whether grape seed proanthocyanidin extract (GSPE) administration recovers the CAF-induced hepatic antioxidant (AOX) misalignment and characterize the chronotherapeutic properties of GSPE. For this purpose, Fischer 344 rats were fed a standard diet (STD) or a CAF and concomitantly treated with GSPE at two time-points (ZT0 vs. ZT12). Animals were euthanized every 6 h and the diurnal rhythms of hepatic ROS-related biomarkers, hepatic metabolites, and AOX gene expression were examined. Interestingly, GSPE treatment was able to recover the diurnal rhythm lost due to the CAF. Moreover, GSPE treatment also increased the acrophase of Sod1, as well as bringing the peak closer to that of the STD group. GSPE also corrected some hepatic metabolites altered by the CAF. Importantly, the differences observed at ZT0 vs. ZT12 due to the time of GSPE administration highlight a chronotherapeutic profile on the proanthocyanin effect. Finally, GSPE could also reduce diet-induced hepatic oxidative stress not only by its ROS-scavenging properties but also by retraining the circadian rhythm of AOX enzymes.

Analysis of Melatonin-Modulating Effects Against Tartrazine-Induced Neurotoxicity in Male Rats: Biochemical, Pathological and Immunohistochemical Markers

Tartrazine (E-102) is one of the most widely used artificial food azo-colors that can be metabolized to highly sensitizing aromatic amines such as sulphanilic acid. These metabolites are oxidized to N-hydroxy derivatives that cause neurotoxicity. Melatonin is a neurohormone. That possesses a free-radical scavenging effect. The present work was mainly designed to evaluate the possible ameliorative role of melatonin against tartrazine induced neurotoxicity in cerebral cortex and cerebellum of male rats. Adult male rats were administered orally with tartrazine (7.5 mg/kg) with or without melatonin (10 mg/kg) daily for four weeks. The data revealed that tartrazine induced redox disruptions as measured by significant (p < 0.05) increased malondialdehyde (MDA) level and inhibition of (GSH) concentration and catalase (CAT), superoxide dismutase (SOD) and glutathione peroxidase (GPx) antioxidant enzyme activities. Besides, brain acetyl cholin (Ach) and gamma-aminobutyric acid (GABA) were elevated while, dopamine (DA) was depleted in trtrazine -treated rats. Moreover, tartrazine caused a significant (p < 0.05) increase in the brain interleukin-6 (IL-6), interleukin-1β (IL-1 β) and tumor necrosis factor-α (TNFα). At the tissue level, tartrazine caused severe histopathological changes in the cerebellum and cerebral cortex of rats. The immunohistochemical results elucidated strong positive expression for Caspase-3 and GFAP and weak immune reaction for BcL2 and synaptophysin in tatrazine- treated rats. The administration of melatonin to tartrazine -administered rats remarkably alleviated all the aforementioned tartrzine-induced effects. It could be concluded that, melatonin has a potent ameliorative effect against tartrazine induced neurotoxicity via the attenuation of oxidative/antioxidative responses.

Desynchronosis: Types, Main Mechanisms, Role in the Pathogenesis of Epilepsy and Other Diseases: A Literature Review

Circadian information is stored in mammalian tissues by an autonomous network of transcriptional feedback loops that have evolved to optimally regulate tissue-specific functions. Currently, stable circadian rhythms of the expression of clock genes (Bmal1/Per2/Cry1, etc.), hormones, and metabolic genes (Glut4/leptin, etc.) have been demonstrated. Desynchronoses are disorders of the body's biorhythms, where the direction and degree of shift of various indicators of the oscillatory process are disturbed. Desynchronosis can be caused by natural conditions or man-made causes. The disruption of circadian rhythms is a risk factor for the appearance of physiological and behavioral disorders and the development of diseases, including epilepsy, and metabolic and oncological diseases. Evidence suggests that seizure activity in the epilepsy phenotype is associated with circadian dysfunction. Interactions between epilepsy and circadian rhythms may be mediated through melatonin, sleep-wake cycles, and clock genes. The correction of circadian dysfunction can lead to a decrease in seizure activity and vice versa. Currently, attempts are being made to pharmacologically correct desynchronosis and related psycho-emotional disorders, as well as combined somatic pathology. On the other hand, the normalization of the light regimen, the regulation of sleep-wake times, and phototherapy as additions to standard treatment can speed up the recovery of patients with various diseases.

Protective effects of melatonin on changes occurring in the experimental autoimmune encephalomyelitis model of multiple sclerosis

BACKGROUND

Melatonin has been related to the pathophysiology of multiple sclerosis (MS), and its anti-inflammatory and immunomodulatory properties have been proved in numerous neurodegenerative diseases. This study aimed to find out whether a melatonin supplement in MS is able to act as a benefit to its clinical status, i.e. oxidative stress, inflammation and indirect biomarkers of bacterial dysbiosis, lipopolysaccharide (LPS) and LPS-binding protein (LBP), verifying its therapeutic potential and its possible clinical use in patients with MS.

METHODS

The animal MS model, experimental autoimmune encephalomyelitis (EAE), was employed whereby 25 male Dark Agouti rats (5 animals per group) were divided into: a control group (not manipulated); a control+vehicle group; a control+melatonin group; an EAE group; an EAE+melatonin group. Melatonin was administered daily for 51 days, at a dose of 1 mg/kg body weight/i.p., once a day, five days a week.

RESULTS

The results from the administration of melatonin demonstrated an improvement in clinical status, a diminution in oxidative stress and inflammation, as well as in bacterial dysbiosis.

CONCLUSION

Melatonin could play an effective role against MS, either alone or as a therapy combined with traditional agents.

A systematic review of the relationship between night shift work and oxidative stress

Night shift workers make up an essential part of the modern workforce. However, night shift workers have higher incidences of late in life diseases and earlier mortality. Night shift workers experience circadian rhythm disruption due to working overnight. Sleep disruption is thought to increase oxidative stress, defined as an imbalance of excess pro-oxidative factors and reactive oxygen species over anti-oxidative activity. Oxidative stress can damage cells, proteins and DNA and can eventually lead to varied chronic diseases such as cancer, diabetes, cardiovascular disease, Alzheimer's and dementia. This review aimed to understand whether night shift workers were at greater risk of oxidative stress. Twelve correlational studies published in 2001-2019 were included in the review that measured the levels of oxidative stress indicators from working a single night shift as well as comparisons between those who regularly work night shifts and only day shifts. All studies had evidence to support the relationship between working night shifts and increased oxidative stress indicators. Specifically, night shift work was associated with increased DNA damage, reduced DNA repair capacity, increased lipid peroxidation, higher levels of reactive oxygen species, and to a lesser extent, a reduction in antioxidant defence. These results suggest a potential link between circadian rhythm disruption in night shift workers with oxidative stress and therefore disease. However, this review is limited by having no longitudinal or experimental studies. Further research is required to infer causality. This further research is recommended to promote the long-term health of night shift workers.

Extended light period in the maternal circadian cycle impairs the reproductive system of the rat male offspring

Alterations in the circadian cycle are known to cause physiological disorders in the hypothalamic-pituitary-adrenal and the hypothalamic-pituitary-gonadal axes in adult individuals. Therefore, the present study aimed to evaluate whether exposure of pregnant rats to constant light can alter the reproductive system development of male offspring. The dams were divided into two groups: a light-dark group (LD), in which pregnant rats were exposed to an LD photoperiod (12 h/12 h) and a light-light (LL) group, in which pregnant rats were exposed to a photoperiod of constant light during the gestation period. After birth, offspring from both groups remained in the normal LD photoperiod (12 h/12 h) until adulthood. One male of each litter was selected and, at adulthood (postnatal day (PND) 90), the trunk blood was collected to measure plasma testosterone levels, testes and epididymis for sperm count, oxidative stress and histopathological analyses, and the spermatozoa from the vas deferens to perform the morphological and motility analyses. Results showed that a photoperiod of constant light caused a decrease in testosterone levels, epididymal weight and sperm count in the epididymis, seminiferous tubule diameter, Sertoli cell number, and normal spermatozoa number. Histopathological damage was also observed in the testes, and stereological alterations, in the LL group. In conclusion, exposure to constant light during the gestational period impairs the reproductive system of male offspring in adulthood.

Tomatoes consumed in-season prevent oxidative stress in Fischer 344 rats: impact of geographical origin

Tomatoes (Lycopersicon esculentum Mill.) constitute an important source of health-promoting compounds including bioactive antioxidants, such as flavonoids, that can differ in terms of composition and quantity depending on the conditions that tomatoes are cultivated. Otherwise, biological rhythms modulate oxidative stress. Therefore, the aim of this study was to evaluate the antioxidant properties of seasonally consumed tomatoes from two different geographical origins (local LT or non-local NLT) in Fischer 344 rats. The results show that LT and NLT have a specific phenolic signature and that each tomato gives a particular response toward biomarkers evaluated, which in turn showed a photoperiod-dependent effect. Remarkably, when tomatoes were administered in-season they improved or sustained antioxidant biomarkers, thus reducing oxidative stress values. It is noteworthy that the protective effect of tomatoes against oxidative stress depends on the geographical origin of the crop. Therefore, tomatoes consumed in-season may improve health by preventing oxidative stress.

Impact of constant light exposure during pregnancy on skin of neonatal New Zealand rabbits: structural and ultrastructural study

Continuous industrial productivity and modern societies have resulted in excess artificial light. The altered circadian rhythm causes many diseases. During intrauterine life, the mother's maternal melatonin rhythm has a major role in influencing organ development. The aim of this study was to investigate the effect of maternal exposure to constant light on the structure and ultrastructure of neonatal skin. Twenty pregnant New Zealand rabbits were divided into two groups (n=10 each): control group (12-h light/dark) and constant light group (24-h light). Plasma maternal melatonin and corticosterone during pregnancy were determined. At the end of the experiment, the dorsal skin of the neonates of both groups was collected and prepared for histological, morphometric, and transmission electron microscopic study. Histological and morphometric results of skin of neonates from the constant light group revealed statistically significantly reduced epidermal thickness, decreased number of hair follicle, increased surface area of collagen, and decreased proliferating cell nuclear antigen (PCNA) positive cells. Ultrastructural examination showed wide intercellular spaces and disrupted desmosomal junctions in the epidermis. Earlier stages of hair follicles were also observed with indented shrunken nuclei, vacuolization, and swollen mitochondria. Dermal fibroblasts with dilated cisternae of rough endoplasmic reticulum containing electron-dense material were detected. Maternal melatonin was significantly reduced in the constant light group while maternal corticosterone showed no significant difference between groups. Therefore, normal maternal circadian rhythm is a key factor for the integrity of neonatal skin structure.

Oxidative Stress in Rats is Modulated by Seasonal Consumption of Sweet Cherries from Different Geographical Origins: Local vs. Non-Local

Sweet cherries (Prunus avium L.) are a source of bioactive compounds, including phenolic compounds, which are antioxidants that contribute to protection against oxidative stress. It is known that the composition of cherries is influenced by external conditions, such as the geographic origin of cultivation, and that biological rhythms have a significant effect on oxidative stress. Therefore, in this study, Fischer 344 rats were exposed to various photoperiods and were supplemented with Brooks sweet cherries from two different geographical origins, local (LC) and non-local (NLC), to evaluate the interaction of supplementation and biological rhythms with regard to the oxidative stress status. The results indicate that the two fruits generated specific effects and that these effects were modulated by the photoperiod. Consumption of sweet cherries in-season, independently of their origin, may promote health by preventing oxidative stress, tending to: enhance antioxidant status, decrease alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activities, reduce liver malondialdehyde (MDA) levels, and maintain constant serum MDA values and reactive oxygen species (ROS) generation.

The pivotal role of melatonin in ameliorating chronic kidney disease by suppression of the renin-angiotensin system in the kidney

Melatonin is a hormone produced by the pineal gland, predominantly at night, and plays a pivotal role in regulating the circadian rhythm as well as a variety of biological functions, including anti-inflammation, anti-oxidation, inhibition of sympathetic nerve activity, and preservation of endothelial cell function. The intrarenal renin-angiotensin system (RAS) is one of the most important contributors in the pathophysiology of chronic kidney disease (CKD) and hypertension, independent of the circulating RAS, due to sodium reabsorption and inflammation and fibrosis in the kidney. However, the relationship between melatonin secretion and intrarenal RAS activation has remained unknown. It has been recently shown that impaired nighttime melatonin secretion is associated with nighttime urinary angiotensinogen excretion, a surrogate marker of intrarenal RAS activation and renal damage in patients with CKD. Moreover, it has also been indicated that melatonin administered exogenously exercises antioxidant effects that ameliorate intrarenal RAS activation and renal injury in chronic progressive CKD animal models. As a result, the new roles of melatonin in suppressing RAS in the kidney via amelioration of reactive oxygen species have been clarified. Therefore, we review the relationship between melatonin and intrarenal RAS activation and indicate the possibility of a new strategy to suppress CKD, which is a risk factor for cardiovascular and end-stage renal diseases.

Melatonin ameliorates intrarenal renin-angiotensin system in a 5/6 nephrectomy rat model

BACKGROUND

Activation of the intrarenal renin-angiotensin system (RAS) plays a critical role in the pathophysiology of chronic kidney disease (CKD) and hypertension. It has been reported that reactive oxygen species (ROS) are important components of intrarenal RAS activation. Melatonin is recognized as a powerful antioxidant, and we recently reported that impaired nighttime melatonin secretion correlates negatively with urinary angiotensinogen excretion, the surrogate marker of intrarenal RAS activity in patients with CKD. However, whether melatonin supplementation ameliorates the augmentation of intrarenal RAS in CKD has remained unknown. We aimed to clarify whether exogenous melatonin ameliorates intrarenal RAS activation via the reduction of ROS production.

METHODS

5/6 Nephrectomized (Nx) rats were used as a chronic progressive CKD model and compared with sham-operated control rats. The Nx rats were divided into untreated Nx rats and melatonin-treated Nx rats. The levels of intrarenal RAS, ROS components, and renal injury were evaluated after 4 weeks of treatment.

RESULTS

Compared with the control rats, the untreated Nx rats exhibited significant increases in intrarenal angiotensinogen, angiotensin II (AngII) type 1 receptors, and AngII, accompanied by elevated blood pressure, higher oxidative stress (8-hydroxy-2'-deoxyguanosine), lower antioxidant (superoxide dismutase) activity, and increased markers of interstitial fibrosis (α-smooth muscle actin, Snail, and type I collagen) in the remnant kidneys. Treatment with melatonin significantly reversed these abnormalities.

CONCLUSION

Antioxidant treatment with melatonin was shown to ameliorate intrarenal RAS activation and renal injury in a 5/6 Nx rat model.

Short-term sleep deprivation with exposure to nocturnal light alters mitochondrial bioenergetics in Drosophila

Many studies have shown the effects of sleep deprivation in several aspects of health and disease. However, little is known about how mitochondrial bioenergetics function is affected under this condition. To clarify this, we developed a simple model of short-term sleep deprivation, in which fruit-flies were submitted to a nocturnal light condition and then mitochondrial parameters were assessed by high resolution respirometry (HRR). Exposure of flies to constant light was able to alter sleep patterns, causing locomotor deficits, increasing ROS production and lipid peroxidation, affecting mitochondrial activity, antioxidant defense enzymes and caspase activity. HRR analysis showed that sleep deprivation affected mitochondrial bioenergetics capacity, decreasing respiration at oxidative phosphorylation (OXPHOS) and electron transport system (ETS). In addition, the expression of genes involved in the response to oxidative stress and apoptosis were increased. Thus, our results suggest a connection between sleep deprivation and oxidative stress, pointing to mitochondria as a possible target of this relationship.

Redox regulation and pro-oxidant reactions in the physiology of circadian systems

Rhythms of approximately 24 h are pervasive in most organisms and are known as circadian. There is a molecular circadian clock in each cell sustained by a feedback system of interconnected "clock" genes and transcription factors. In mammals, the timing system is formed by a central pacemaker, the suprachiasmatic nucleus, in coordination with a collection of peripheral oscillators. Recently, an extensive interconnection has been recognized between the molecular circadian clock and the set of biochemical pathways that underlie the bioenergetics of the cell. A principle regulator of metabolic networks is the flow of electrons between electron donors and acceptors. The concomitant reduction and oxidation (redox) reactions directly influence the balance between anabolic and catabolic processes. This review summarizes and discusses recent findings concerning the mutual and dynamic interactions between the molecular circadian clock, redox reactions, and redox signaling. The scope includes the regulatory role played by redox coenzymes (NAD(P)+/NAD(P)H, GSH/GSSG), reactive oxygen species (superoxide anion, hydrogen peroxide), antioxidants (melatonin), and physiological events that modulate the redox state (feeding condition, circadian rhythms) in determining the timing capacity of the molecular circadian clock. In addition, we discuss a purely metabolic circadian clock, which is based on the redox enzymes known as peroxiredoxins and is present in mammalian red blood cells and in other biological systems. Both the timing system and the metabolic network are key to a better understanding of widespread pathological conditions such as the metabolic syndrome, obesity, and diabetes.

Melatonin Prevents Mitochondrial Damage Induced by Doxorubicin in Mouse Fibroblasts Through Ampk-Ppar Gamma-Dependent Mechanisms

BACKGROUND Doxorubicin (brand name: Adriamycin®) is used to treat solid tissue cancer but it also affects noncancerous tissues. Its mechanism of cytotoxicity is probably related to increased oxidation, mitochondrial dysfunction, and apoptosis. Melatonin is reported to have antiapoptotic and antioxidative effects. The aim of this study was to determine whether melatonin would counteract in vitro cytotoxicity of doxorubicin in mouse fibroblasts and determine the pathway of its action against doxorubicin-induced apoptosis. MATERIAL AND METHODS We measured markers of apoptosis (cytochrome-c, mitochondrial membrane potential, and apoptotic cell number) and oxidative stress (total oxidant and antioxidant status) and calculated oxidant stress index in 4 groups of fibroblasts: controls, melatonin-treated, doxorubicin-treated, and fibroblasts concomittantly treated with a combination of melatonin and doxorubicin. RESULTS Melatonin given with doxorubicin succesfully countered apoptosis generated by doxorubicin alone, which points to its potential as a protective agent against cell death in doxorubicin chemotherapy. This also implies that patients should be receiving doxorubicin treatment when their physiological level of melatonin is at its highest, which is early in the morning. CONCLUSIONS This physiological level may not be high enough to overcome doxorubicin-induced oxidative stress, but adjuvant melatonin treatment may improve quality of life. Further research is needed to verify our findings.

Protecting the melatonin rhythm through circadian healthy light exposure

Currently, in developed countries, nights are excessively illuminated (light at night), whereas daytime is mainly spent indoors, and thus people are exposed to much lower light intensities than under natural conditions. In spite of the positive impact of artificial light, we pay a price for the easy access to light during the night: disorganization of our circadian system or chronodisruption (CD), including perturbations in melatonin rhythm. Epidemiological studies show that CD is associated with an increased incidence of diabetes, obesity, heart disease, cognitive and affective impairment, premature aging and some types of cancer. Knowledge of retinal photoreceptors and the discovery of melanopsin in some ganglion cells demonstrate that light intensity, timing and spectrum must be considered to keep the biological clock properly entrained. Importantly, not all wavelengths of light are equally chronodisrupting. Blue light, which is particularly beneficial during the daytime, seems to be more disruptive at night, and induces the strongest melatonin inhibition. Nocturnal blue light exposure is currently increasing, due to the proliferation of energy-efficient lighting (LEDs) and electronic devices. Thus, the development of lighting systems that preserve the melatonin rhythm could reduce the health risks induced by chronodisruption. This review addresses the state of the art regarding the crosstalk between light and the circadian system.