scholarly journals Impact of nutrients on circadian rhythmicity

2015 ◽  
Vol 308 (5) ◽  
pp. R337-R350 ◽  
Author(s):  
Johanneke E. Oosterman ◽  
Andries Kalsbeek ◽  
Susanne E. la Fleur ◽  
Denise D. Belsham
Keyword(s):  
Circadian Rhythms ◽  
Circadian Clock ◽  
The Body ◽  
Circadian Rhythmicity ◽  
Energy Status ◽  
Peripheral Oscillators ◽  
Peripheral Clocks ◽  
Central Pacemaker ◽  
Almost All ◽  
The Impact

The suprachiasmatic nucleus (SCN) in the mammalian hypothalamus functions as an endogenous pacemaker that generates and maintains circadian rhythms throughout the body. Next to this central clock, peripheral oscillators exist in almost all mammalian tissues. Whereas the SCN is mainly entrained to the environment by light, peripheral clocks are entrained by various factors, of which feeding/fasting is the most important. Desynchronization between the central and peripheral clocks by, for instance, altered timing of food intake can lead to uncoupling of peripheral clocks from the central pacemaker and is, in humans, related to the development of metabolic disorders, including obesity and Type 2 diabetes. Diets high in fat or sugar have been shown to alter circadian clock function. This review discusses the recent findings concerning the influence of nutrients, in particular fatty acids and glucose, on behavioral and molecular circadian rhythms and will summarize critical studies describing putative mechanisms by which these nutrients are able to alter normal circadian rhythmicity, in the SCN, in non-SCN brain areas, as well as in peripheral organs. As the effects of fat and sugar on the clock could be through alterations in energy status, the role of specific nutrient sensors will be outlined, as well as the molecular studies linking these components to metabolism. Understanding the impact of specific macronutrients on the circadian clock will allow for guidance toward the composition and timing of meals optimal for physiological health, as well as putative therapeutic targets to regulate the molecular clock.

scholarly journals Respiratory Care in Corona

2021 ◽  
Vol 58 (2) ◽  
pp. 613-620
Author(s):  
Mustafa Amdani, Dr. Swaroopa Chakole
Keyword(s):  
Severe Acute Respiratory Syndrome ◽  
Human Life ◽  
The Body ◽  
Respiratory Care ◽  
The Novel ◽  
Specific Therapy ◽  
History Of ◽  
Novel Coronavirus ◽  
Almost All ◽  
The Impact

BACKGROUND The expanse of the coronavirus disease 2019 or COVID-19 is huge. The impact is multispectral and affected almost all aspects of human life. SUMMARY Respiratory impact of the COVID-19 is the most felt and widely reported impact. As the novel coronavirus maintained its history of affecting lungs as seen previously in severe acute respiratory syndrome (SARS) outbreak. Ventilators and oxygen support system are required mostly in comorbid patients particularly amongpatientsbearing illnesses like asthma, bronchial impairment and so on. CONCLUSION More study needs to be done in order to assess the impact on the respiratory functioning of the body. Respiratory care must be including proper instruments so that more efficient result can be obtained. Research is needed to promote the invention of specific therapy for targeted action for respiratory functioning improvement.

Evolution Analysis of the Circadian Clock Protein KaiB

2013 ◽  
Vol 647 ◽  
pp. 391-395
Author(s):  
Liu Sen ◽  
Song Liu
Keyword(s):  
Circadian Rhythms ◽  
Circadian Clock ◽  
Feedback Loop ◽  
Circadian System ◽  
Circadian Rhythmicity ◽  
Physiological Functions ◽  
Clock System ◽  
Evolution Analysis ◽  
Clock Protein

Regulation of daily physiological functions with approximate a 24-hour periodicity, or circadian rhythms, is a characteristic of eukaryotes. So far, cyanobacteria are only known prokaryotes reported to possess circadian rhythmicity. The circadian system in cyanobacteria comprises both a post-translational oscillator (PTO) and a transcriptional/translational feedback loop (TTFL). The PTO can be reconstituted in vitro with three purified proteins (KaiA, KaiB, and KaiC) with the existence of ATP. Phase of the nanoclockwork has been associated with the phosphorylation states of KaiC, with KaiA promoting the phosphorylation of KaiC, and KaiB de-phosphorylating KaiC. Here we studied the evolution of the KaiB protein. The result will be helpful in understanding the evolution of the circadian clock system.

scholarly journals Entrainment of peripheral clock genes by cortisol

2012 ◽  
Vol 44 (11) ◽  
pp. 607-621 ◽  
Author(s):  
Panteleimon D. Mavroudis ◽  
Jeremy D. Scheff ◽  
Steve E. Calvano ◽  
Stephen F. Lowry ◽  
Ioannis P. Androulakis
Keyword(s):  
Clock Genes ◽  
Dynamic Regime ◽  
The Body ◽  
Molecular Function ◽  
Frequency Range ◽  
Peripheral Tissues ◽  
Peripheral Clock ◽  
Peripheral Clocks ◽  
Central Pacemaker ◽  
Peripheral Cells

Circadian rhythmicity in mammals is primarily driven by the suprachiasmatic nucleus (SCN), often called the central pacemaker, which converts the photic information of light and dark cycles into neuronal and hormonal signals in the periphery of the body. Cells of peripheral tissues respond to these centrally mediated cues by adjusting their molecular function to optimize organism performance. Numerous systemic cues orchestrate peripheral rhythmicity, such as feeding, body temperature, the autonomic nervous system, and hormones. We propose a semimechanistic model for the entrainment of peripheral clock genes by cortisol as a representative entrainer of peripheral cells. This model demonstrates the importance of entrainer's characteristics in terms of the synchronization and entrainment of peripheral clock genes, and predicts the loss of intercellular synchrony when cortisol moves out of its homeostatic amplitude and frequency range, as has been observed clinically in chronic stress and cancer. The model also predicts a dynamic regime of entrainment, when cortisol has a slightly decreased amplitude rhythm, where individual clock genes remain relatively synchronized among themselves but are phase shifted in relation to the entrainer. The model illustrates how the loss of communication between the SCN and peripheral tissues could result in desynchronization of peripheral clocks.

scholarly journals Re-Setting the Circadian Clock Using Exercise against Sarcopenia

2020 ◽  
Vol 21 (9) ◽  
pp. 3106 ◽  
Author(s):  
Youngju Choi ◽  
Jinkyung Cho ◽  
Mi-Hyun No ◽  
Jun-Won Heo ◽  
Eun-Jeong Cho ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Circadian Rhythms ◽  
Circadian Clock ◽  
Intervention Strategy ◽  
Muscle Metabolism ◽  
Circadian Disruption ◽  
Adverse Health Outcomes ◽  
Exercise Timing ◽  
Underlying Mechanisms ◽  
The Impact

Sarcopenia is defined as the involuntary loss of skeletal muscle mass and function with aging and is associated with several adverse health outcomes. Recently, the disruption of regular circadian rhythms, due to shift work or nocturnal lifestyle, is emerging as a novel deleterious factor for the development of sarcopenia. The underlying mechanisms responsible for circadian disruption-induced sarcopenia include molecular circadian clock and mitochondrial function associated with the regulation of circadian rhythms. Exercise is a potent modulator of skeletal muscle metabolism and is considered to be a crucial preventative and therapeutic intervention strategy for sarcopenia. Moreover, emerging evidence shows that exercise, acting as a zeitgeber (time cue) of the skeletal muscle clock, can be an efficacious tool for re-setting the clock in sarcopenia. In this review, we provide the evidence of the impact of circadian disruption on skeletal muscle loss resulting in sarcopenia. Furthermore, we highlight the importance of exercise timing (i.e., scheduled physical activity) as a novel therapeutic strategy to target circadian disruption in skeletal muscle.

Limitations of the Avp-IRES2-Cre (JAX #023530) and Vip-IRES-Cre (JAX #010908) Models for Chronobiological Investigations

2019 ◽  
Vol 34 (6) ◽  
pp. 634-644 ◽  
Author(s):  
Arthur H. Cheng ◽  
Samuel W. Fung ◽  
Hai-Ying Mary Cheng
Keyword(s):  
Confounding Factor ◽  
The Body ◽  
Mouse Strains ◽  
Extreme Caution ◽  
Specific Manner ◽  
A Cell ◽  
Peripheral Clocks ◽  
Cell Type Specific ◽  
Encoding Gene ◽  
The Impact

The principal circadian pacemaker in mammals, the suprachiasmatic nucleus (SCN), expresses a number of neuropeptides that facilitate intercellular synchrony, helping to generate coherent outputs to peripheral clocks throughout the body. In particular, arginine vasopressin (AVP)– and vasoactive intestinal peptide (VIP)–expressing neurons have been recognized as crucial subpopulations within the SCN and have thus been the focus of many chronobiological studies. Here, we analyze the neuropeptide expression of 2 popular transgenic mouse strains commonly used to direct or restrict Cre-mediated recombination to AVP- and VIP-ergic neurons. The Avp-IRES2-Cre (JAX #023530) and Vip-IRES-Cre (JAX #010908) “driver” mouse strains express the Cre recombinase under the control of the endogenous Avp or Vip gene, respectively, allowing scientists either to ablate their gene of interest or to overexpress a transgene in a cell type–specific manner. Although these are potentially very powerful tools for chronobiologists and other scientists studying AVP- and VIP-ergic neurons, we found that neuropeptide expression in these mice is significantly decreased when an IRES(2)-Cre cassette is inserted downstream of the neuropeptide-encoding gene locus. The impact of IRES(2)-Cre cassette insertion on neuropeptide expression may be a confounding factor in many experimental designs. Our findings suggest that extreme caution must be exercised when using these mouse models to avoid misinterpretation of empirical results.

scholarly journals Disruption of gene expression rhythms in mice lacking secretory vesicle proteins IA-2 and IA-2β

2012 ◽  
Vol 303 (6) ◽  
pp. E762-E776 ◽  
Author(s):  
Sohan Punia ◽  
Kyle K. Rumery ◽  
Elizabeth A. Yu ◽  
Christopher M. Lambert ◽  
Abner L. Notkins ◽  
...  
Keyword(s):  
Gene Expression ◽  
Secretory Vesicle ◽  
Diurnal Rhythms ◽  
Double Knockout ◽  
Peripheral Tissues ◽  
Oscillatory Function ◽  
Peripheral Oscillators ◽  
Central Pacemaker ◽  
The Impact ◽  
Single Knockout

Insulinoma-associated protein (IA)-2 and IA-2β are transmembrane proteins involved in neurotransmitter secretion. Mice with targeted disruption of both IA-2 and IA-2β (double-knockout, or DKO mice) have numerous endocrine and physiological disruptions, including disruption of circadian and diurnal rhythms. In the present study, we have assessed the impact of disruption of IA-2 and IA-2β on molecular rhythms in the brain and peripheral oscillators. We used in situ hybridization to assess molecular rhythms in the hypothalamic suprachiasmatic nuclei (SCN) of wild-type (WT) and DKO mice. The results indicate significant disruption of molecular rhythmicity in the SCN, which serves as the central pacemaker regulating circadian behavior. We also used quantitative PCR to assess gene expression rhythms in peripheral tissues of DKO, single-knockout, and WT mice. The results indicate significant attenuation of gene expression rhythms in several peripheral tissues of DKO mice but not in either single knockout. To distinguish whether this reduction in rhythmicity reflects defective oscillatory function in peripheral tissues or lack of entrainment of peripheral tissues, animals were injected with dexamethasone daily for 15 days, and then molecular rhythms were assessed throughout the day after discontinuation of injections. Dexamethasone injections improved gene expression rhythms in liver and heart of DKO mice. These results are consistent with the hypothesis that peripheral tissues of DKO mice have a functioning circadian clockwork, but rhythmicity is greatly reduced in the absence of robust, rhythmic physiological signals originating from the SCN. Thus, IA-2 and IA-2β play an important role in the regulation of circadian rhythms, likely through their participation in neurochemical communication among SCN neurons.

scholarly journals Mechanisms of Communication in the Mammalian Circadian Timing System

2019 ◽  
Vol 20 (2) ◽  
pp. 343 ◽  
Author(s):  
Mariana Astiz ◽  
Isabel Heyde ◽  
Henrik Oster
Keyword(s):  
Current Knowledge ◽  
The Body ◽  
Dark Cycle ◽  
Timing System ◽  
Circadian Timing System ◽  
Neuroendocrine Mechanisms ◽  
Peripheral Clocks ◽  
Central Pacemaker ◽  
And Function ◽  
Therapeutic Settings

24-hour rhythms in physiology and behaviour are organized by a body-wide network of endogenous circadian clocks. In mammals, a central pacemaker in the hypothalamic suprachiasmatic nucleus (SCN) integrates external light information to adapt cellular clocks in all tissues and organs to the external light-dark cycle. Together, central and peripheral clocks co-regulate physiological rhythms and functions. In this review, we outline the current knowledge about the routes of communication between the environment, the main pacemakers and the downstream clocks in the body, focusing on what we currently know and what we still need to understand about the communication mechanisms by which centrally and peripherally controlled timing signals coordinate physiological functions and behaviour. We highlight recent findings that shed new light on the internal organization and function of the SCN and neuroendocrine mechanisms mediating clock-to-clock coupling. These findings have implications for our understanding of circadian network entrainment and for potential manipulations of the circadian clock system in therapeutic settings.

scholarly journals Rhythmicity of the intestinal microbiota is regulated by gender and the host circadian clock

2015 ◽  
Vol 112 (33) ◽  
pp. 10479-10484 ◽  
Author(s):  
Xue Liang ◽  
Frederic D. Bushman ◽  
Garret A. FitzGerald
Keyword(s):  
Circadian Rhythms ◽  
Circadian Clock ◽  
Fecal Microbiota ◽  
Circadian Rhythmicity ◽  
Absolute Amount ◽  
Gene Encoding ◽  
Host Behavior ◽  
Clock Component ◽  
Time Of Feeding ◽  
Changing Light

In mammals, multiple physiological, metabolic, and behavioral processes are subject to circadian rhythms, adapting to changing light in the environment. Here we analyzed circadian rhythms in the fecal microbiota of mice using deep sequencing, and found that the absolute amount of fecal bacteria and the abundance of Bacteroidetes exhibited circadian rhythmicity, which was more pronounced in female mice. Disruption of the host circadian clock by deletion of Bmal1, a gene encoding a core molecular clock component, abolished rhythmicity in the fecal microbiota composition in both genders. Bmal1 deletion also induced alterations in bacterial abundances in feces, with differential effects based on sex. Thus, although host behavior, such as time of feeding, is of recognized importance, here we show that sex interacts with the host circadian clock, and they collectively shape the circadian rhythmicity and composition of the fecal microbiota in mice.

scholarly journals The vascular clock: a new insight into endothelial cells and pericytes crosstalk

2021 ◽  
Vol 42 (Supplement_1) ◽  
Author(s):  
V Mastrullo ◽  
R S Matos ◽  
J H McVey ◽  
P Gupta ◽  
P Madeddu ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Circadian Rhythms ◽  
Circadian Clock ◽  
Blood Vessels ◽  
Molecular Clock ◽  
Clock Genes ◽  
Public Institution ◽  
Perivascular Cells ◽  
Rhythmic Expression ◽  
The Impact

Abstract Background/Introduction Circadian rhythms, defined as biological oscillations with a period of circa 24h, regulate many physiological processes in the cardiovascular system, such as vascular function, vascular tone, blood pressure, heart rate and thrombus formation [1]. The vasculature responds to the main pacemaker located in the brain, but it also possesses its own clock. Indeed, a molecular clock has been identified in endothelial cells (EC) and smooth muscle cells (SMC). The disruption of the circadian clock profoundly affects cardiovascular functionality with adverse cardiovascular events such as myocardial infarction or stroke showing a 24h rhythmicity with a peak incidence in the early morning. Among several mechanisms affected by circadian dysregulation, angiogenesis plays a fundamental role in homeostasis and development of new blood vessels. EC and pericytes (PC) are the two main cell populations in the capillaries, and their physical and paracrine interaction drives and regulates the sprouting. However, the presence and the role of circadian rhythms in pericytes and whether the molecular clock affects the endothelial/pericyte interactions remain unexplored. Purpose The aim of this study is to identify a molecular clock in human vascular pericytes and elucidate the impact of the circadian clock on the formation of new blood vessels. Methods Human primary PC were synchronised and the rhythmicity of clock genes measured by luminescence, immunofluorescence, and qPCR. Synchronised PC were co-cultured with Bmal1::LUC human primary EC. The effect of PC synchronisation and circadian clock disruption by shRNA on EC clock genes and angiogenic potential were measured by luminescence and Matrigel assay, respectively. A macroporous polyurethane scaffold was developed for 3D co-cultures. Results PC presented rhythmic expression of the principal circadian genes with a circa 24h period but in our experimental setting, EC did not show circadian rhythmicity. Synchronised PC supported the rhythmic expression of the clock gene Bmal1 in EC in a contact co-culture system, suggesting a secondary form of EC molecular clock regulation. Non-contact co-cultures failed to synchronise EC. Furthermore, when the clock was disrupted in PC, their capacity to support EC's tube-forming capacity on Matrigel was impaired; clock disruption in EC did not affect angiogenesis, supporting the hypothesis that a disrupted clock in perivascular cells affects angiogenesis. In a 3D tissue engineering scaffold seeded with both EC and PC, the synchronisation of the clock led to the development of organised vascular-like structures around the scaffold's pores, as compared to the non-synchronised condition where cells appeared disorganised. Conclusion This study defines for the first time the existence of an endogenous molecular circadian clock in perivascular cells and suggests implications for circadian clock synchronisation in physiological and therapeutic angiogenesis. FUNDunding Acknowledgement Type of funding sources: Public Institution(s). Main funding source(s): University of Surrey Doctoral CollegeUniversity of Surrey Bioprocess and Biochemical Engineering (BioProChem) Group.

Circadian Rhythm, Clock Genes, and Hypertension: Recent Advances in Hypertension

Hypertension ◽  
2021 ◽  
Author(s):  
Hannah M. Costello ◽  
Michelle L. Gumz
Keyword(s):  
Circadian Rhythm ◽  
Circadian Clock ◽  
Clock Genes ◽  
Adverse Outcomes ◽  
The Body ◽  
Perivascular Adipose Tissue ◽  
Area Of Interest ◽  
Recent Advances ◽  
Increased Risk ◽  
Peripheral Clocks

Accumulating evidence suggests that the molecular circadian clock is crucial in blood pressure (BP) control. Circadian rhythms are controlled by the central clock, which resides in the suprachiasmatic nucleus of the hypothalamus and peripheral clocks throughout the body. Both light and food cues entrain these clocks but whether these cues are important for the circadian rhythm of BP is a growing area of interest. The peripheral clocks in the smooth muscle, perivascular adipose tissue, liver, adrenal gland, and kidney have been recently implicated in the regulation of BP rhythm. Dysregulation of the circadian rhythm of BP is associated with adverse cardiorenal outcomes and increased risk of cardiovascular mortality. In this review, we summarize the most recent advances in peripheral clocks as BP regulators, highlight the adverse outcomes of disrupted circadian BP rhythm in hypertension, and provide insight into potential future work in areas exploring the circadian clock in BP control and chronotherapy. A better understanding of peripheral clock function in regulating the circadian rhythm of BP will help pave the way for targeted therapeutics in the treatment of circadian BP dysregulation and hypertension.

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