scholarly journals Resetting Process of Peripheral Circadian Gene Expression after the Combined Reversal of Feeding Schedule and Light/Dark Cycle Via a 24-h Light Period Transition in Rats

2010 ◽  
pp. 581-590
Author(s):  
T Wu ◽  
Y Ni ◽  
F Zhuge ◽  
Z Fu
Keyword(s):  
Time Course ◽  
Clock Genes ◽  
Dark Period ◽  
Light Period ◽  
Feeding Schedule ◽  
Circadian Gene ◽  
Dark Cycle ◽  
Peripheral Clocks ◽  
Effect Of Light

To investigate the effect of light cue on the resetting of the peripheral clocks, we examined the resetting processes of clock genes (Per1, Per2, Bmal1, Cry1, Dec1, and Rev-erbα) in the liver and heart of rats after the feeding and light-dark (LD) reversal via a 24-h light period transition. The liver clock was reset quickly within 3 days, while the heart clock needed a longer time course of 5-7 days to be completely re-entrained. Moreover, the reentrainment of Per1 and Per2 in the liver clock was more rapid than that of the other four clock genes, suggesting the important role of these two clock genes in initiating the circadian resetting of the hepatic clock. However, the resetting rates of these two clock genes were as similar as the others in the heart clock. Therefore, the resetting mechanisms underlining these two peripheral clocks may be totally distinct. Furthermore, the reentrainment of the liver and heart clocks were relatively lengthened after the feeding and LD reversal via a light period transition compared to a dark period transition, suggesting a simultaneous shift of feeding schedule and the LD cycle may facilitate the circadian resetting in rats.

scholarly journals Shifting eating to the circadian rest phase misaligns the peripheral clocks with the master SCN clock and leads to a metabolic syndrome

2015 ◽  
Vol 112 (48) ◽  
pp. E6691-E6698 ◽  
Author(s):  
Atish Mukherji ◽  
Ahmad Kobiita ◽  
Manohar Damara ◽  
Nisha Misra ◽  
Hamid Meziane ◽  
...  
Keyword(s):  
Metabolic Syndrome ◽  
Molecular Level ◽  
Dark Period ◽  
Active Phase ◽  
Light Period ◽  
Dark Cycle ◽  
Peripheral Clocks ◽  
Molecular Signals ◽  
Glucagon Receptors

The light-entrained master central circadian clock (CC) located in the suprachiasmatic nucleus (SCN) not only controls the diurnal alternance of the active phase (the light period of the human light-dark cycle, but the mouse dark period) and the rest phase (the human dark period, but the mouse light period), but also synchronizes the ubiquitous peripheral CCs (PCCs) with these phases to maintain homeostasis. We recently elucidated in mice the molecular signals through which metabolic alterations induced on an unusual feeding schedule, taking place during the rest phase [i.e., restricted feeding (RF)], creates a 12-h PCC shift. Importantly, a previous study showed that the SCN CC is unaltered during RF, which creates a misalignment between the RF-shifted PCCs and the SCN CC-controlled phases of activity and rest. However, the molecular basis of SCN CC insensitivity to RF and its possible pathological consequences are mostly unknown. Here we deciphered, at the molecular level, how RF creates this misalignment. We demonstrate that the PPARα and glucagon receptors, the two instrumental transducers in the RF-induced shift of PCCs, are not expressed in the SCN, thereby preventing on RF a shift of the master SCN CC and creating the misalignment. Most importantly, this RF-induced misalignment leads to a misexpression (with respect to their normal physiological phase of expression) of numerous CC-controlled homeostatic genes, which in the long term generates in RF mice a number of metabolic pathologies including diabetes, obesity, and metabolic syndrome, which have been reported in humans engaged in shift work schedules.

Regulation of circadian gene expression in the kidney by light and food cues in rats

2010 ◽  
Vol 298 (3) ◽  
pp. R635-R641 ◽  
Author(s):  
Tao Wu ◽  
Yinhua Ni ◽  
Yue Dong ◽  
Jiafeng Xu ◽  
Xiaohong Song ◽  
...  
Keyword(s):  
Gene Expression ◽  
Circadian Rhythm ◽  
Clock Genes ◽  
Feeding Schedule ◽  
Circadian Gene ◽  
Food Cues ◽  
Peripheral Clocks ◽  
Synchronization Effect ◽  
The Individual ◽  
External Time

Although studies involving the circadian response to external time cues indicate that the peripheral clocks are dominated mainly by food cues, whether and how changes in the light and food cues affect the circadian rhythm of the renal clock is still largely unknown. In the present study, we found that the circadian phases of Bmal1, Clock, Cry1, Per1, and Per2 were altered differently by the stimuli of food and light cues in the kidney. After the individual reversal of the light-dark (LD) cycle for 7 days, Per1 displayed a 4-h phase delay, whereas the peak phases of Bmal1, Clock, Cry1 and Per2 almost remained the same as those in the control condition. With regard to the feeding-induced circadian resetting of the renal clock, we found that the resetting processes of clock genes could not be completed within 7 days, suggesting a weak synchronization effect of the food cue on the renal circadian clock. Moreover, the reentrainment of the clock genes was greatly enhanced after the reversal of both the feeding schedule and the LD cycle. Noticeably, the phases of Per1 and Clock were shifted most rapidly by 12 h within 3 days after the simultaneous reversal of the feeding schedule and the LD cycle, whereas their peak phases were only shifted by 4 h and 8 h, respectively, on the 7th day after the individual reversal of the feeding schedule. Thus Per1 and Clock may play important roles in the light-induced resetting of the circadian rhythms in the kidney.

Stimulation of Melatonin Receptors Decreases Calcium Levels in Xenopus Tectal Cells by Activating GABAC Receptors

2005 ◽  
Vol 94 (2) ◽  
pp. 968-978 ◽  
Author(s):  
Claudia Prada ◽  
Susan B. Udin ◽  
Allan F. Wiechmann ◽  
Irina V. Zhdanova
Keyword(s):  
Receptor Antagonist ◽  
Dark Period ◽  
Light Period ◽  
Melatonin Receptors ◽  
Receptor Activity ◽  
Calcium Dynamics ◽  
Rt Pcr ◽  
Dark Cycle ◽  
Bath Application ◽  
Stimulation Of

To investigate the physiological effects of melatonin receptors in the Xenopus tectum, we have used the fluorescent indicator Fluo-4 AM to monitor calcium dynamics of cells in tectal slices. Bath application of KCl elicited fluorescence increases that were reduced by melatonin. This effect was stronger at the end of the light period than at the end of the dark period. Melatonin increased γ-aminobutyric acid-C (GABAC)–receptor activity, as demonstrated by the ability of the GABAC-receptor antagonists, picrotoxin and TPMPA, to abolish the effects of melatonin. In contrast, neither the GABAA-receptor antagonist bicuculline nor the GABAB-receptor antagonist CGP 35348 diminished the effects of melatonin. RT-PCR analyses revealed expression of the 3 known melatonin receptors, MT1 (Mel1a), MT2 (Mel1b), and Mel1c. Because the effect of melatonin on tectal calcium increases was antagonized by an MT2-selective antagonist, 4-P-PDOT, we performed Western blot analyses with an antibody to the MT2 receptor; the data indicate that the MT2 receptor is expressed primarily as a dimeric complex and is glycosylated. The receptor is present in higher amounts at the end of the light period than at the end of the dark period, in a pattern complementary to the changes in melatonin levels, which are higher during the night than during the day. These results imply that melatonin, acting by MT2 receptors, modulates GABAC receptor activity in the optic tectum and that this effect is influenced by the light–dark cycle.

Monophasic and diphasic patterns of the circadian caecotrophy rhythm of rabbits

1982 ◽  
Vol 16 (1) ◽  
pp. 1-6 ◽  
Author(s):  
Burghart Jilge
Keyword(s):  
Dark Period ◽  
Continuous Light ◽  
Light Period ◽  
Period Length ◽  
Rodent Species ◽  
Average Period ◽  
Dark Cycle

The circadian caecotrophy rhythm was synchronized with the light-dark cycle of 12 : 12 h. During this the rabbits practised caecotrophy regularly during the light period. While most rabbits manifested 1 caecotrophy per 24 h (monophasic caecotrophy), some had an additional caecotrophy during the dark period (diphasic caecotrophy). During continuous light the circadian caecotrophy rhythm ran free monophasically, even in those rabbits which were diphasic under the preceding 12 : 12 regime. The average period length amounted to 24·7 ± 0·3 h. Following restoration of the 12 : 12 routine animals reestablished their original caecotrophy pattern. In a further test the caecotrophy pattern remained constant during a constant 12 : 12 regimen, but changed in 7 of 16 animals when the photoperiod was reduced first to 60 min and then to 2 × 60 min light every 24 h. The reduction of the lit time resulted in an increased occurrence of diphasic animals. Details of synchronization of the caecotrophy rhythm with the different light-dark schedules are given. These results accord with data obtained in nocturnal rodent species.

Diurnal Differences in the Innermost Surface of the S2 Layer in Differentiating Tracheids of Cryptomeria japonica Corresponding to a Light-Dark Cycle

Holzforschung ◽  
2003 ◽  
Vol 57 (6) ◽  
pp. 567-573 ◽  
Author(s):  
Y. Hosoo ◽  
M. Yoshida ◽  
T. Imai ◽  
T. Okuyama
Keyword(s):  
Cryptomeria Japonica ◽  
Dark Period ◽  
Amorphous Material ◽  
Light Period ◽  
Cellulose Microfibrils ◽  
Dark Phase ◽  
Diurnal Changes ◽  
Dark Cycle ◽  
Tangential Strain ◽  
S2 Layer

Summary This paper describes the effect of light on the diurnal change in the innermost surface of developing secondary walls. Cryptomeria japonica D. Don saplings were grown in two growth chambers, in which temperature and relative humidity were kept constant and the light-dark phase of the photoperiod varied. One chamber reproduced the natural light-dark phase, while the other reversed it. Samples of differentiating xylem were collected during the dark period when the tangential strain, used as an index of volumetric changes in differentiating cells, was high, and during the light period when the tangential strain was low. The innermost surface of developing secondary walls in differentiating tracheids was observed by field emission scanning electron microscopy. In the specimens collected during the dark period, amorphous material was observed and the cell wall surface was immunogold-labeled with an anti-glucomannan antiserum. In the specimens collected during the light period, cellulose microfibrils were clearly evident, and amorphous material and immunogold labeling were rarely observed. These results demonstrate that the diurnal changes in the innermost surface of developing secondary walls correspond to the light-dark cycle over 24 h.

scholarly journals The SCN Clock Governs Circadian Transcription Rhythms in Murine Epididymal White Adipose Tissue

2016 ◽  
Vol 31 (6) ◽  
pp. 577-587 ◽  
Author(s):  
Isa Kolbe ◽  
Jana Husse ◽  
Gabriela Salinas ◽  
Thomas Lingner ◽  
Mariana Astiz ◽  
...  
Keyword(s):  
Adipose Tissue ◽  
White Adipose Tissue ◽  
Clock Genes ◽  
Mutant Mice ◽  
Immune Functions ◽  
Whole Genome Microarray ◽  
Peripheral Clocks ◽  
Epididymal White Adipose Tissue ◽  
External Time

The circadian master pacemaker in the suprachiasmatic nucleus (SCN) orchestrates peripheral clocks in various organs and synchronizes them with external time, including those in adipose tissue, which displays circadian oscillations in various metabolic and endocrine outputs. Because our knowledge about the instructive role of the SCN clock on peripheral tissue function is based mainly on SCN lesion studies, we here used an alternative strategy employing the Cre/ loxP system to functionally delete the SCN clock in mice. We performed whole-genome microarray hybridizations of murine epididymal white adipose tissue (eWAT) RNA preparations to characterize the role of the SCN clock in eWAT circadian transcriptome regulation. Most of the rhythmic transcripts in control animals were not rhythmic in SCN mutants, but a significant number of transcripts were rhythmic only in mutant eWAT. Core clock genes were rhythmic in both groups, but as was reported before for other tissues, rhythms were dampened and phase advanced in mutant animals. In SCN-mutant mice, eWAT lost the rhythm of metabolic pathway–related transcripts, while transcripts gaining rhythms in SCN-mutant mice were associated with various immune functions. These data reveal a complex interaction of SCN-derived and local circadian signals in the regulation of adipose transcriptome programs.

scholarly journals Light represses transcription of asparagine synthetase genes in photosynthetic and nonphotosynthetic organs of plants.

1991 ◽  
Vol 11 (10) ◽  
pp. 4966-4972 ◽  
Author(s):  
F Y Tsai ◽  
G Coruzzi
Keyword(s):  
Gene Expression ◽  
Direct Effect ◽  
Transcriptional Repression ◽  
Time Course ◽  
Nicotiana Plumbaginifolia ◽  
Asparagine Synthetase ◽  
General Phenomenon ◽  
Dark Cycle ◽  
Normal Light ◽  
Effect Of Light

Asparagine synthetase (AS) mRNA in Pisum sativum accumulates preferentially in plants grown in the dark. Nuclear run-on experiments demonstrate that expression of both the AS1 and AS2 genes is negatively regulated by light at the level of transcription. A decrease in the transcriptional rate of the AS1 gene can be detected as early as 20 min after exposure to light. Time course experiments reveal that the levels of AS mRNA fluctuate dramatically during a "normal" light/dark cycle. This is due to a direct effect of light and not to changes associated with circadian rhythm. A novel finding is that the light-repressed expression of the AS1 gene is as dramatic in nonphotosynthetic organs such as roots as it is in leaves. Experiments demonstrate that the small amount of light which passes through the soil is sufficient to repress AS1 expression in roots, indicating that light has a direct effect on AS1 gene expression in roots. The negative regulation of AS gene expression by light was shown to be a general phenomenon in plants which also occurs in nonlegumes such as Nicotiana plumbaginifolia and Nicotiana tabacum. Thus, the AS genes can serve as a model with which to dissect the molecular basis for light-regulated transcriptional repression in plants.

Circadian rhythms of thermoregulation in the squirrel monkey (Saimiri sciureus)

1993 ◽  
Vol 265 (4) ◽  
pp. R781-R785 ◽  
Author(s):  
E. L. Robinson ◽  
V. H. Demaria-Pesce ◽  
C. A. Fuller
Keyword(s):  
Circadian Rhythm ◽  
Oxygen Consumption ◽  
Time Course ◽  
Squirrel Monkeys ◽  
Light Period ◽  
Saimiri Sciureus ◽  
Co2 Production ◽  
Daily Rhythms ◽  
Dark Cycle ◽  
Time Courses

Phase or amplitude differences between rhythms in heat production (HP) and heat loss (HL) have been suggested to account for the circadian rhythm in body temperature (Tb). To describe the relationships among these rhythms in a primate, five unrestrained squirrel monkeys (1.0-1.3 kg) were studied using combined direct and indirect calorimetry, with telemetry of Tb and activity, in a 24-h light-dark cycle (LD 12:12) at 25 +/- 0.5 degrees C. Dry (D; sensible) HL, evaporative (E) HL, HP (oxygen consumption and CO2 production), Tb, and activity were measured at 10-min intervals for a week. Tb, activity, HP, and HL displayed daily rhythms, peaking during the light period. Although the timing of peaks was not significantly different, the diurnal increase in Tb was seen to result from a delayed increase in DHL, and possibly, EHL, relative to increased HP. The nocturnal decrease in Tb was due to different time courses of decrease in HP and HL, with no clear lag in HL. The rhythm in Tb therefore resulted from both phase and time course differences in HP and HL rhythms.

scholarly journals Desipramine restores the alterations in circadian entrainment induced by prenatal exposure to glucocorticoids

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Stefan Spulber ◽  
Mirko Conti ◽  
Frederik Elberling ◽  
Marilena Raciti ◽  
Dasiel Oscar Borroto-Escuela ◽  
...  
Keyword(s):  
Mrna Expression ◽  
Feedback Loop ◽  
Nuclear Translocation ◽  
Clock Genes ◽  
Negative Feedback Loop ◽  
Dark Cycle ◽  
Peripheral Oscillators ◽  
Noradrenaline Reuptake ◽  
Peripheral Clocks ◽  
Central Clock

Abstract Alterations in circadian rhythms are closely linked to depression, and we have shown earlier that progressive alterations in circadian entrainment precede the onset of depression in mice exposed in utero to excess glucocorticoids. The aim of this study was to investigate whether treatment with the noradrenaline reuptake inhibitor desipramine (DMI) could restore the alterations in circadian entrainment and prevent the onset of depression-like behavior. C57Bl/6 mice were exposed to dexamethasone (DEX—synthetic glucocorticoid analog, 0.05 mg/kg/day) between gestational day 14 and delivery. Male offspring aged 6 months (mo) were treated with DMI (10 mg/kg/day in drinking water) for at least 21 days before behavioral testing. We recorded spontaneous activity using the TraffiCage™ system and found that DEX mice re-entrained faster than controls after an abrupt advance in light-dark cycle by 6 h, while DMI treatment significantly delayed re-entrainment. Next we assessed the synchronization of peripheral oscillators with the central clock (located in the suprachiasmatic nucleus—SCN), as well as the mechanisms required for entrainment. We found that photic entrainment of the SCN was apparently preserved in DEX mice, but the expression of clock genes in the hippocampus was not synchronized with the light-dark cycle. This was associated with downregulated mRNA expression for arginine vasopressin (AVP; the main molecular output entraining peripheral clocks) in the SCN, and for glucocorticoid receptor (GR; required for the negative feedback loop regulating glucocorticoid secretion) in the hippocampus. DMI treatment restored the mRNA expression of AVP in the SCN and enhanced GR-mediated signaling by upregulating GR expression and nuclear translocation in the hippocampus. Furthermore, DMI treatment at 6 mo prevented the onset of depression-like behavior and the associated alterations in neurogenesis in 12-mo-old DEX mice. Taken together, our data indicate that DMI treatment enhances GR-mediated signaling and restores the synchronization of peripheral clocks with the SCN and support the hypothesis that altered circadian entrainment is a modifiable risk factor for depression.

scholarly journals The Angiotensin-Melatonin Axis

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
Luciana A. Campos ◽  
Jose Cipolla-Neto ◽  
Fernanda G. Amaral ◽  
Lisete C. Michelini ◽  
Michael Bader ◽  
...  
Keyword(s):  
Circadian Rhythms ◽  
Metabolic Disorders ◽  
Clock Genes ◽  
Renin Angiotensin System ◽  
Angiotensin System ◽  
Beneficial Effects ◽  
Progression Of Disease ◽  
The Central Nervous System ◽  
Peripheral Clocks

Accumulating evidence indicates that various biological and neuroendocrine circadian rhythms may be disrupted in cardiovascular and metabolic disorders. These circadian alterations may contribute to the progression of disease. Our studies direct to an important role of angiotensin II and melatonin in the modulation of circadian rhythms. The brain renin-angiotensin system (RAS) may modulate melatonin synthesis, a hormone with well-established roles in regulating circadian rhythms. Angiotensin production in the central nervous system may not only influence hypertension but also appears to affect the circadian rhythm of blood pressure. Drugs acting on RAS have been proven effective in the treatment of cardiovascular and metabolic disorders including hypertension and diabetes mellitus (DM). On the other hand, since melatonin is capable of ameliorating metabolic abnormalities in DM and insulin resistance, the beneficial effects of RAS blockade could be improved through combined RAS blocker and melatonin therapy. Contemporary research is evidencing the existence of specific clock genes forming central and peripheral clocks governing circadian rhythms. Further research on the interaction between these two neurohormones and the clock genes governing circadian clocks may progress our understanding on the pathophysiology of disease with possible impact on chronotherapeutic strategies.

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