Search results for "Circadian clock"

The roles of gut microbiota and circadian rhythm in the cardiovascular protective effects of polyphenols

2019

Polyphenols are secondary metabolites of plants that have been widely studied for their health benefits as antioxidants. In the last decade, several clinical trials and epidemiological studies have shown that long-term consumption of polyphenol-rich diet protects against chronic diseases such as cancers and cardiovascular diseases. Current cardiovascular studies have also suggested an important role of gut microbiota and circadian rhythm in the pathogenesis metabolic and cardiovascular diseases. It is known that polyphenols can modulate the composition of core gut microbiota and interact with circadian clocks. In this article, we summarize recent findings, review the molecular mechanisms an…

2021

Every organism has an intrinsic biological rhythm that orchestrates biological processes in adjusting to daily environmental changes. Circadian rhythms are maintained by networks of molecular clocks throughout the core and peripheral tissues, including immune cells, blood vessels, and perivascular adipose tissues. Recent findings have suggested strong correlations between the circadian clock and cardiovascular diseases. Desynchronization between the circadian rhythm and body metabolism contributes to the development of cardiovascular diseases including arteriosclerosis and thrombosis. Circadian rhythms are involved in controlling inflammatory processes and metabolisms, which can influence t…

Circadian rhythms in the pathogenesis of gastrointestinal diseases

2018

The etiology of digestive pathologies such as irritable bowel syndrome (IBS), inflammatory bowel diseases (IBD) and cancer is not yet fully understood. In recent years, several studies have evidenced circadian variations in mechanisms involved in digestive health. In situations of disturbed circadian rhythms (chronodisruption) where the central clock and the peripheral clocks receive incoherent signals, the synchronicity is lost producing implications for health. This lack of coordination could alter the tissue function and cause long term damage to the organs. Life habits such as sleep, physical exercise, social interaction, and feeding times are determinants for stability and integrity of…

Circadian Rhythm and Concentration of Melatonin in Breast Cancer Patients

2020

Background: Melatonin is a biomarker of the central circadian clock and its chronobiotic actions entraining circadian rhythms to the light-dark cycle are well known. Reduction in melatonin levels and altered circadian rhythms have been associated with a high risk of breast cancer. Melatonin has also shown to display anti-proliferative effects on breast cancer growth and proliferation. Evaluation of melatonin circadian rhythm alterations in patients bearing breast cancer may have interesting prognostic and therapeutic applications. Objective: To review studies evaluating the circadian rhythm of melatonin in breast cancer patients. The effects of surgery and chemotherapy on melatonin secreti…

Circadian clock of Drosophila montana is adapted to high variation in summer day lengths and temperatures prevailing at high latitudes

2016

Photoperiodic regulation of the circadian rhythms in insect locomotor activity has been studied in several species, but seasonal entrainment of these rhythms is still poorly understood. We have traced the entrainment of activity rhythm of northern Drosophila montana flies in a climate chamber mimicking the photoperiods and day and night temperatures that the flies encounter in northern Finland during the summer. The experiment was started by transferring freshly emerged females into the chamber in early and late summer conditions to obtain both non-diapausing and diapausing females for the studies. The locomotor activity of the females and daily changes in the expression levels of two core …

Rev-Erb modulates retinal visual processing and behavioral responses to light

2016

International audience; The circadian clock is thought to adjust retinal sensitivity to ambient light levels, yet the involvement of specific clock genes is poorly understood. We explored the potential role of the nuclear receptor subfamily 1, group D, member 1 (REV-ERB; or NR1D1) in this respect. In light-evoked behavioral tests, compared with wild-type littermates, Rev-Erb(-/-) mice showed enhanced negative masking at low light levels (0.1 lx). Rev-Erb(-/-) mouse retinas displayed significantly higher numbers of intrinsically photosensitive retinal ganglion cells (ipRGCs; 62% more compared with wild-type) and more intense melanopsin immunostaining of individual ipRGCs. In agreement with a…

The influence of meal frequency and timing on health in humans: The role of fasting

2019

The influence of meal frequency and timing on health and disease has been a topic of interest for many years. While epidemiological evidence indicates an association between higher meal frequencies and lower disease risk, experimental trials have shown conflicting results. Furthermore, recent prospective research has demonstrated a significant increase in disease risk with a high meal frequency (≥6 meals/day) as compared to a low meal frequency (1–2 meals/day). Apart from meal frequency and timing we also have to consider breakfast consumption and the distribution of daily energy intake, caloric restriction, and night-time eating. A central role in this complex scenario is playe…

Characterisation, analysis of expression and localisation of circadian clock genes from the perspective of photoperiodism in the aphid Acyrthosiphon …

2017

Aphids are typical photoperiodic insects that switch from viviparous parthenogenetic reproduction typical of long day seasons to oviparous sexual reproduction triggered by the shortening of photoperiod in autumn yielding an overwintering egg in which an embryonic diapause takes place. While the involvement of the circadian clock genes in photoperiodism in mammals is well established, there is still some controversy on their participation in insects. The availability of the genome of the pea aphid Acyrthosiphon pisum places this species as an excellent model to investigate the involvement of the circadian system in the aphid seasonal response. In the present report, we have advanced in the c…

2018

Abstract To function properly, organisms must adjust their physiology, behavior and metabolism in response to a suite of varying environmental conditions. One of the central regulators of these changes is organisms’ internal circadian clock, and recent evidence has suggested that the clock genes are also important in the regulation of seasonal adjustments. In particular, thermosensitive splicing of the core clock gene timeless in a cosmopolitan fly, Drosophila melanogaster, has implicated this gene to be involved in thermal adaptation. To further investigate this link we examined the splicing of timeless in a northern malt fly species, Drosophila montana, which can withstand much colder cli…

Structural and mechanistic insights into the interaction of the circadian transcription factor BMAL1 with the KIX domain of the CREB-binding protein

2019

JBC papers in press xx, 16604-16619 (2019). doi:10.1074/jbc.RA119.009845