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Journal of Neurochemistry Apr 2021The circadian timing system governs daily biological rhythms, synchronising physiology and behaviour to the temporal world. External time cues, including the light-dark... (Review)
Review
The circadian timing system governs daily biological rhythms, synchronising physiology and behaviour to the temporal world. External time cues, including the light-dark cycle and timing of food intake, provide daily signals for entrainment of the central, master circadian clock in the hypothalamic suprachiasmatic nuclei (SCN), and of metabolic rhythms in peripheral tissues, respectively. Chrono-nutrition is an emerging field building on the relationship between temporal eating patterns, circadian rhythms, and metabolic health. Evidence from both animal and human research demonstrates adverse metabolic consequences of circadian disruption. Conversely, a growing body of evidence indicates that aligning food intake to periods of the day when circadian rhythms in metabolic processes are optimised for nutrition may be effective for improving metabolic health. Circadian rhythms in glucose and lipid homeostasis, insulin responsiveness and sensitivity, energy expenditure, and postprandial metabolism, may favour eating patterns characterised by earlier temporal distribution of energy. This review details the molecular basis for metabolic clocks, the regulation of feeding behaviour, and the evidence for meal timing as an entraining signal for the circadian system in animal models. The epidemiology of temporal eating patterns in humans is examined, together with evidence from human intervention studies investigating the metabolic effects of morning compared to evening energy intake, and emerging chrono-nutrition interventions such as time-restricted feeding. Chrono-nutrition may have therapeutic application for individuals with and at-risk of metabolic disease and convey health benefits within the general population.
Topics: Animals; Circadian Rhythm; Energy Metabolism; Feeding Behavior; Homeostasis; Humans; Neurons; Photoperiod
PubMed: 33222161
DOI: 10.1111/jnc.15246 -
Proceedings of the National Academy of... Jan 2023The gut microbiome is well known to impact host physiology and health. Given widespread control of physiology by circadian clocks, we asked how the microbiome interacts...
The gut microbiome is well known to impact host physiology and health. Given widespread control of physiology by circadian clocks, we asked how the microbiome interacts with circadian rhythms in the gut. The microbiome did not cycle in flies fed ad libitum, and timed feeding (TF) drove limited cycling only in clockless flies. However, TF and loss of the microbiome influenced the composition of the gut cycling transcriptome, independently and together. Moreover, both interventions increased the amplitude of rhythmic gene expression, with effects of TF at least partly due to changes in histone acetylation. Contrary to expectations, timed feeding rendered animals more sensitive to stress. Analysis of microbiome function in circadian physiology revealed that germ-free flies reset more rapidly with shifts in the light:dark cycle. We propose that the microbiome stabilizes cycling in the host gut to prevent rapid fluctuations with changing environmental conditions.
Topics: Animals; Circadian Rhythm; Circadian Clocks; Drosophila; Photoperiod; Gastrointestinal Microbiome
PubMed: 36689661
DOI: 10.1073/pnas.2217532120 -
Current Biology : CB Apr 2016While we do not yet understand all the functions of sleep, its critical role for normal physiology and behaviour is evident. Its amount and temporal pattern depend on...
While we do not yet understand all the functions of sleep, its critical role for normal physiology and behaviour is evident. Its amount and temporal pattern depend on species and condition. Humans sleep about a third of the day with the longest, consolidated episode during the night. The change in lifestyle from hunter-gatherers via agricultural communities to densely populated industrialized centres has certainly affected sleep, and a major concern in the medical community is the impact of insufficient sleep on health [1,2]. One of the causal mechanisms leading to insufficient sleep is altered exposure to the natural light-dark cycle. This includes the wide availability of electric light, attenuated exposure to daylight within buildings, and evening use of light-emitting devices, all of which decrease the strength of natural light-dark signals that entrain circadian systems [3].
Topics: Circadian Rhythm; Humans; Light; Melatonin; Photoperiod; Sleep; Sleep Disorders, Circadian Rhythm
PubMed: 27046809
DOI: 10.1016/j.cub.2016.01.071 -
International Journal of Environmental... Dec 2022The circadian rhythm regulates biological processes that occur within 24 h in living organisms. It plays a fundamental role in maintaining biological functions and... (Review)
Review
The circadian rhythm regulates biological processes that occur within 24 h in living organisms. It plays a fundamental role in maintaining biological functions and responds to several inputs, including food intake, light/dark cycle, sleep/wake cycle, and physical activity. The circadian timing system comprises a central clock located in the suprachiasmatic nucleus (SCN) and tissue-specific clocks in peripheral tissues. Several studies show that the desynchronization of central and peripheral clocks is associated with an increased incidence of insulin resistance (IR) and related diseases. In this review, we discuss the current knowledge of molecular and cellular mechanisms underlying the impact of circadian clock dysregulation on insulin action. We focus our attention on two possible mediators of this interaction: the phosphatases belonging to the pleckstrin homology leucine-rich repeat protein phosphatase family (PHLPP) family and the deacetylase Sirtuin1. We believe that literature data, herein summarized, suggest that a thorough change of life habits, with the return to synchronized food intake, physical activity, and rest, would doubtless halt the vicious cycle linking IR to dysregulated circadian rhythms. However, since such a comprehensive change may be incompatible with the demand of modern society, clarifying the pathways involved may, nonetheless, contribute to the identification of therapeutic targets that may be exploited to cure or prevent IR-related diseases.
Topics: Humans; Circadian Clocks; Insulin Resistance; Circadian Rhythm; Suprachiasmatic Nucleus; Photoperiod
PubMed: 36612350
DOI: 10.3390/ijerph20010029 -
Seminars in Cell & Developmental Biology Jun 2022Circadian rhythms are ~24 h cycles of behavior and physiology that are generated by a network of molecular clocks located in nearly every tissue in the body. In... (Review)
Review
Circadian rhythms are ~24 h cycles of behavior and physiology that are generated by a network of molecular clocks located in nearly every tissue in the body. In mammals, the circadian system is organized hierarchically such that the suprachiasmatic nucleus (SCN) is the main circadian clock that receives light information from the eye and entrains to the light-dark cycle. The SCN then coordinates the timing of tissue clocks so internal rhythms are aligned with environmental cycles. Estrogens interact with the circadian system to regulate biological processes. At the molecular level, estrogens and circadian genes interact to regulate gene expression and cell biology. Estrogens also regulate circadian behavior across the estrous cycle. The timing of ovulation during the estrous cycle requires coincident estrogen and SCN signals. Studies using circadian gene reporter mice have also elucidated estrogen regulation of peripheral tissue clocks and metabolic rhythms. This review synthesizes current understanding of the interplay between estrogens and the circadian system, with a focus on female rodents, in regulating molecular, physiological, and behavioral processes.
Topics: Animals; Circadian Clocks; Circadian Rhythm; Estrogens; Female; Mammals; Mice; Photoperiod; Suprachiasmatic Nucleus
PubMed: 33975754
DOI: 10.1016/j.semcdb.2021.04.010 -
Dark-light cycle disrupts bone metabolism and suppresses joint deterioration in osteoarthritic rats.Arthritis Research & Therapy Jun 2022Light alteration affects the internal environment and metabolic homeostasis of the body through circadian rhythm disorders (CRD). CRD is one of the factors that induce...
BACKGROUND
Light alteration affects the internal environment and metabolic homeostasis of the body through circadian rhythm disorders (CRD). CRD is one of the factors that induce and accelerate osteoarthritis (OA). Therefore, the aim of this study was to evaluate the effects of continuous dark-light (DL) cycle on joint inflammation, bone structure, and metabolism in normal and OA Sprague-Dawley (SD) rats.
METHODS
Interleukin (IL)-1β, IL-6, inducible nitric oxide synthase (iNOS), and tumor necrosis factor (TNF)-α were used to evaluate the systemic inflammation in rats. The pathological changes and inflammatory reactions of the cartilage and synovium of the knee joint in rats were evaluated by Safranin O-fast green and immunological staining. Bone turnover was assessed by histomorphometry and μCT scanning, as well as bone metabolism markers and proteins. The expression changes of clock proteins BMAL1, NR1D1, PER3, and CRY1 in representative tissues were detected by western blotting.
RESULTS
DL cycle significantly inhibited body weight gain in normal and OA rats. The levels of proinflammatory factors in the peripheral blood circulation and degradation enzymes in the cartilage were significantly decreased in OA+DL rats. DL cycle significantly destroyed the structure of subchondral bone in hindlimbs of OA rats and reduced trabecular bone numbers. The decrease of bone mineral density (BMD), percent bone volume with respect to total bone volume (BV/TV), trabecular number (TB.N), osteoclast number, and mineralization could also be found. The ratio of the receptor activator of nuclear factor-kappa B ligand/osteoprotegerin (RANKL/OPG) in the bone marrow of OA rats was markedly increased under DL, along with the activation of the mononuclear/phagocyte system. The expression of representative clock proteins and genes BMAL1, PER3, and CRY1 were markedly changed in the tissues of OA+DL rats.
CONCLUSIONS
These results suggested that DL cycle dampened the arthritis and promoted bone resorption and bone mass loss. DL cycle affects bone turnover by regulating osteoclast production in osteoarthritic rats.
Topics: ARNTL Transcription Factors; Animals; CLOCK Proteins; Osteoarthritis; Photoperiod; Rats; Rats, Sprague-Dawley
PubMed: 35765090
DOI: 10.1186/s13075-022-02832-8 -
International Journal of Molecular... Mar 2022Life on earth has evolved under the influence of regularly recurring changes in the environment, such as the 24 h light/dark cycle. Consequently, organisms have... (Review)
Review
Life on earth has evolved under the influence of regularly recurring changes in the environment, such as the 24 h light/dark cycle. Consequently, organisms have developed endogenous clocks, generating 24 h (circadian) rhythms that serve to anticipate these rhythmic changes. In addition to these circadian rhythms, which persist in constant conditions and can be entrained to environmental rhythms, light drives rhythmic behavior and brain function, especially in nocturnal laboratory rodents. In recent decades, research has made great advances in the elucidation of the molecular circadian clockwork and circadian light perception. This review summarizes the role of light and the circadian clock in rhythmic brain function, with a focus on the complex interaction between the different components of the mammalian circadian system. Furthermore, chronodisruption as a consequence of light at night, genetic manipulation, and neurodegenerative diseases is briefly discussed.
Topics: Animals; Brain; Circadian Clocks; Circadian Rhythm; Mammals; Photoperiod; Suprachiasmatic Nucleus
PubMed: 35269920
DOI: 10.3390/ijms23052778 -
Ugeskrift For Laeger Sep 2018Circadian and seasonal rhythm disturbances are prominent in patients with psychiatric disorders. Properly timed and dosed light of specific spectral composition... (Review)
Review
Circadian and seasonal rhythm disturbances are prominent in patients with psychiatric disorders. Properly timed and dosed light of specific spectral composition stabilises mood and sleep through serotonergic mechanisms and through input to the master circadian clock in the hypothalamus. Correctly administered, light can be used as an effective treatment for seasonal and non-seasonal depression and for stabilising the sleep-wake cycle. Blocking blue light in the evening may provide a non-pharmacological anti-manic tool. Current developments use dynamic lighting built into somatic and psychiatric hospitals to maximise the beneficial effects of light.
Topics: Circadian Clocks; Circadian Rhythm; Depressive Disorder; Humans; Light; Photoperiod; Phototherapy; Sleep Phase Chronotherapy; Vision Disorders
PubMed: 30348255
DOI: No ID Found -
Nutricion Hospitalaria Jun 2021Background: most organisms inhabiting this planet have rhythmic functions in cycles that approximate 24 hours as a result of evolutionary adaptation. Disruption of these...
Background: most organisms inhabiting this planet have rhythmic functions in cycles that approximate 24 hours as a result of evolutionary adaptation. Disruption of these rhythms causes disruption in many bodily functions, including energy expenditure and consumption, and lipid and glucose metabolism, in addition to altering several biochemical parameters. Objective: the aim of this study was to determine the effect of altering the light-dark cycle on diurnal and nocturnal food consumption and body weight in rats. Material and methods: three experiments were carried out with an experimental group and a control group in each one. The groups included six males with an age of four months at the beginning of the experiment. Each experiment was 30 days long, starting with a baseline of 10 days and then inverting the light-dark cycle for another 20 days. In the first experiment the inversion took place at the end of the baseline period; in the second, the inversion was performed on days 10 and 20; in the third experiment inversions occurred every five days following the initial 10 days of baseline. Results: our results show a lower body weight gain in the experimental groups when compared to the control groups. Conclusions: significant differences in total consumption of food were not found, but were seen in the patterns of day and night consumption, along with a tendency to develop alterations characteristic of metabolic syndrome, which increased with the frequency of light-dark cycle inversion.
Topics: Animals; Body Weight; Eating; Male; Photoperiod; Rats
PubMed: 33749303
DOI: 10.20960/nh.03392 -
Plant, Cell & Environment Mar 2021Light is important for plants as an energy source and a developmental signal, but it can also cause stress to plants and modulates responses to stress. Excess and... (Review)
Review
Light is important for plants as an energy source and a developmental signal, but it can also cause stress to plants and modulates responses to stress. Excess and fluctuating light result in photoinhibition and reactive oxygen species (ROS) accumulation around photosystems II and I, respectively. Ultraviolet light causes photodamage to DNA and a prolongation of the light period initiates the photoperiod stress syndrome. Changes in light quality and quantity, as well as in light duration are also key factors impacting the outcome of diverse abiotic and biotic stresses. Short day or shady environments enhance thermotolerance and increase cold acclimation. Similarly, shade conditions improve drought stress tolerance in plants. Additionally, the light environment affects the plants' responses to biotic intruders, such as pathogens or insect herbivores, often reducing growth-defence trade-offs. Understanding how plants use light information to modulate stress responses will support breeding strategies to enhance crop stress resilience. This review summarizes the effect of light as a stressor and the impact of the light environment on abiotic and biotic stress responses. There is a special focus on the role of the different light receptors and the crosstalk between light signalling and stress response pathways.
Topics: Light; Photoperiod; Plant Physiological Phenomena; Plants; Stress, Physiological
PubMed: 33190307
DOI: 10.1111/pce.13948