Photic Response Parameters of Circadian Rhythms in The Spinifex Hopping Mouse, Notomys alexis.

1996 ◽  
Vol 19 (1) ◽  
pp. 11
Author(s):  
A.J.P. Francis ◽  
G.J. Coleman
Keyword(s):  
Circadian Rhythms ◽  
Phase Relations ◽  
Constant Light ◽  
Constant Darkness ◽  
Biological Clocks ◽  
Circadian Activity ◽  
Activity Rhythms ◽  
Controlled Conditions ◽  
Australian Native Rodent ◽  
Photic Response

Circadian rhythms are generated endogenously by biological clocks or 'pacemakers', which are responsive to significant environmental stimuli termed zeitgebers. Interactions between pacemakers and zeitgebers provide the basis for synchronisation by light-dark (LD) cycles, and the characteristics of each of these elements determines the phase-relations maintained between an animal's circadian activity rhythms and the natural temporal environment. We report here the basic photic response parameters for an Australian native rodent, Notomys alexis. Under controlled conditions of constant darkness or constant light, N. alexis were found to 'free-run', and with periods different from 24 hours. Under LD cycles N. alexis were strictly nocturnal although, compared to other rodents, entrainment to LD cycles was relatively unstable. This may indicate that N. alexis are not strongly dependent on the LD cycle as a zeitgeber.

Effects of daily melatonin injections on activity rhythms of rats in constant light

1987 ◽  
Vol 253 (1) ◽  
pp. R101-R107 ◽  
Author(s):  
M. J. Chesworth ◽  
V. M. Cassone ◽  
S. M. Armstrong
Keyword(s):  
Locomotor Activity ◽  
Saline Solution ◽  
Constant Light ◽  
Constant Darkness ◽  
Circadian Activity ◽  
Activity Rhythms ◽  
Melatonin Administration ◽  
Free Running ◽  
Circadian Patterns ◽  
Phase Relationships

Although from pinealectomy studies the pineal body does not appear to participate in the generation of circadian rhythms of mammals, daily injections of the pineal hormone melatonin entrain free-running locomotor activity rhythms of rats in constant darkness. The aim of the present study was to determine whether rats whose circadian activity and drinking rhythms were disrupted in constant light (LL) could be synchronized by daily melatonin administration. Rats were subjected to a regime of gradually increasing photoperiod until they were maintained in LL. Rats whose rhythms became disrupted or showed intact free-running rhythms were injected daily with either melatonin (1 mg/kg) or vehicle (ethanol-saline) solution. Daily melatonin injections either synchronized or partly synchronized disrupted circadian patterns of activity. In contrast to previous findings from experiments conducted in constant darkness, melatonin did not entrain but only partly synchronized intact free-running rhythms. Results are interpreted in terms of melatonin acting on the coupling or phase relationships between oscillators generating circadian locomotor activity rhythms.

Entrainment of Syrian hamster circadian activity rhythms by neonatal melatonin injections

1996 ◽  
Vol 270 (3) ◽  
pp. R533-R540 ◽  
Author(s):  
J. Grosse ◽  
A. Velickovic ◽  
F. C. Davis
Keyword(s):  
Circadian Rhythms ◽  
Suprachiasmatic Nucleus ◽  
Syrian Hamster ◽  
Circadian Activity ◽  
Syrian Hamsters ◽  
Activity Rhythms ◽  
Vehicle Injection ◽  
Two Phases ◽  
Melatonin Injection

The circadian rhythms of fetal and neonatal rodents are entrained by their mother. This entrainment is dependent upon the maternal suprachiasmatic nucleus (SCN), but the mechanism of entrainment is unknown. Administration of the pineal hormone melatonin to pregnant, SCN-lesioned female Syrian hamsters entrains the activity rhythms of their hamster pups. The aim of this study was to determine whether melatonin injected directly in neonatal Syrian hamsters is able to entrain circadian rhythms and, if so, for how long this effect persists during development. Injection of melatonin in two groups of hamster pups at opposite phases on postnatal days 1-5 entrained the onset of activity rhythms on the day of weaning to two phases 10.67 h apart. Melatonin injection did not entrain activity rhythms to opposite phases on either postnatal days 6-10 or 21-25. Vehicle injection did not entrain animals to opposite phases at any of the ages studied. These results demonstrate that melatonin is able to act directly on the neonate to cause entrainment and that this effect disappears after postnatal day 6.

scholarly journals The effects of Levilactobacillus brevis on the physiological parameters and gut microbiota composition of rats subjected to desynchronosis

2021 ◽  
Vol 20 (1) ◽  
Author(s):  
Evgenii I. Olekhnovich ◽  
Ekaterina G. Batotsyrenova ◽  
Roman A. Yunes ◽  
Vadim A. Kashuro ◽  
Elena U. Poluektova ◽  
...  
Keyword(s):  
Circadian Rhythms ◽  
Gut Microbiota ◽  
Relative Abundance ◽  
Reduced Glutathione ◽  
Physiological Parameters ◽  
Male Rats ◽  
Constant Light ◽  
Constant Darkness ◽  
Microbiota Composition ◽  
Gut Microbiota Composition

Abstract Background All living organisms have developed during evolution complex time-keeping biological clocks that allowed them to stay attuned to their environments. Circadian rhythms cycle on a near 24 h clock. These encompass a variety of changes in the body ranging from blood hormone levels to metabolism, to the gut microbiota composition and others. The gut microbiota, in return, influences the host stress response and the physiological changes associated with it, which makes it an important determinant of health. Lactobacilli are traditionally consumed for their prophylactic and therapeutic benefits against various diseases, namely, the inflammatory bowel syndrome, and even emerged recently as promising psychobiotics. However, the potential role of lactobacilli in the normalization of circadian rhythms has not been addressed. Results Two-month-old male rats were randomly divided into three groups and housed under three different light/dark cycles for three months: natural light, constant light and constant darkness. The strain Levilactobacillus brevis 47f was administered to rats at a dose of 0.5 ml per rat for one month and The rats were observed for the following two months. As a result, we identified the biomarkers associated with intake of L. brevis 47f. Changing the light regime for three months depleted the reserves of the main buffer in the cell—reduced glutathione. Intake of L. brevis 47f for 30 days restored cellular reserves of reduced glutathione and promoted redox balance. Our results indicate that the levels of urinary catecholamines correlated with light/dark cycles and were influenced by intake of L. brevis 47f. The gut microbiota of rats was also influenced by these factors. L. brevis 47f intake was associated with an increase in the relative abundance of Faecalibacterium and Roseburia and a decrease in the relative abundance of Prevotella and Bacteroides. Conclusions The results of this study show that oral administration of L. brevis 47f, for one month, to rats housed under abnormal lightning conditions (constant light or constant darkness) normalized their physiological parameters and promoted the gut microbiome's balance.

Circadian rhythms and depression: effects of exercise in an animal model

1999 ◽  
Vol 276 (1) ◽  
pp. R152-R161 ◽  
Author(s):  
Leah C. Solberg ◽  
Teresa H. Horton ◽  
Fred W. Turek
Keyword(s):  
Circadian Rhythms ◽  
Depressive Disorders ◽  
Activity Rhythm ◽  
Sucrose Solution ◽  
Forced Swim Test ◽  
Total Activity ◽  
Constant Darkness ◽  
Activity Rhythms ◽  
Running Wheels ◽  
And Control

There is a clear link between altered circadian rhythms and depressive disorders, although the nature of this relationship is unknown. In addition, exercise affects both mood and alters clock function. To investigate the relationship between circadian rhythms, depression, and exercise, 3-wk-old mice housed on a 12:12-h light-dark cycle were exposed to chronic stress (CS) for 6 wk before being placed into constant darkness (DD). One-half of both the control and stressed mice were given access to a running wheel. Stressed mice consumed significantly less of a 2% sucrose solution during CS and exhibited a significant increase in immobility in the forced swim test 3 wk after the termination of stress relative to control mice. These effects were more pronounced in mice without running wheels. Stressed mice also exhibited altered percent distribution of total activity and increased fragmentation of daily activity rhythms during CS relative to control mice. Alterations in percent distribution were more pronounced in animals without running wheels. No activity rhythm changes were seen in DD, and there were no differences in light-induced phase shifts between stressed and control mice. These results suggest that CS causes long-term depressive-like symptoms but does not have long-lasting effects on activity rhythms. These changes were more pronounced in mice without running wheels, suggesting that exercise may protect against the harmful effects of stress.

Social cues modulate free-running circadian activity rhythms in the diurnal rodent, Octodon degus

1997 ◽  
Vol 273 (2) ◽  
pp. R797-R804 ◽  
Author(s):  
N. Goel ◽  
T. M. Lee
Keyword(s):  
Active Phase ◽  
Social Cues ◽  
Constant Darkness ◽  
Circadian Activity ◽  
Mutual Synchronization ◽  
Octodon Degus ◽  
Activity Rhythms ◽  
Female Partners ◽  
Free Running ◽  
Activity Onset

Two experiments assessed the effects of social cues and daily disturbance on the circadian locomotor activity rhythms of Octodon degus housed in constant darkness. In experiment 1, females in free-running conditions were housed alone or with entrained female partners ("donors") in cages on either side of a mesh barrier. Donors were removed daily and entrained to 1 h of light, and as a control, the cages of singly housed animals were rustled daily coincident with donor removal and replacement. None of the animals housed alone entrained to daily disturbances presented during the active phase, and seven of eight degus failed to show changes in the circadian period (tau) or phase of their rhythms. In contrast, although the presence of entrained donors did not elicit full entrainment of free-running rhythms, five of six animals demonstrated partial entrainment for 5-12 days (of 30 days), four of six altered phase of activity onset, and six of six lengthened tau of circadian rhythms. In experiment 2, females whose free-running circadian activity rhythms were at least 10 h out of phase were housed together in pairs. None of the pairs demonstrated mutual synchronization of their activity rhythms, although 8 of 12 degus modified phase of activity onset and 9 of 12 animals altered tau. We conclude social information in the absence of light, is sufficient for partial entrainment and for changes in tau and phase of free-running rhythms in this diurnal rodent.

Continuous light or darkness and circadian periodic mitosis and metabolism in C and D8 mice

1961 ◽  
Vol 201 (2) ◽  
pp. 227-230 ◽  
Author(s):  
Franz Halberg ◽  
Cyrus P. Barnum
Keyword(s):  
Cell Division ◽  
Circadian Rhythms ◽  
Deoxyribonucleic Acid ◽  
Acid Metabolism ◽  
Specific Activity ◽  
Continuous Light ◽  
Liver Parenchyma ◽  
Constant Light ◽  
Constant Darkness ◽  
Spot Check

In immature C mice exposed first to alternating 12 hr of light and 12 hr of darkness (LD), and maintained thereafter in constant darkness for several days, the circadian rhythms in hepatic and pinnal mitosis are demonstrable by spot checks made at the approximate times of LD-synchronized peak and trough. Spot checks at same times in mice of same stock and age, kept for several days in constant light, reveal the cell division rhythm of liver parenchyma, but not that of pinnal epidermis. In immature D8 mice kept for several days in constant darkness, rhythms in hepatic mitosis, phospholipid, ribonucleic and deoxyribonucleic acid metabolism persist, while cell division rhythm in ear pinna of same animals is not detectable with the particular spot check used. In mice of same stock and age, on the 4th day in constant light, a significant rhythm persists in the relative specific activity of the hepatic phospholipid; timing of this metabolic cellular rhythm is drastically desynchronized from the reference standard of a 24-hr clock. Data reveal persistence of some mitotic and metabolic circadian rhythms under conditions studied, with phase drifts or phase shifts of these rhythms occurring both in relation to the 24-hr clock and among the rhythms themselves. These changes in external and internal timing of a circadian system are more extensive in constant light than in constant darkness.

Circadian activity of the white sucker, Catostomus commersoni: comparison of individual and shoaling fish

1980 ◽  
Vol 58 (8) ◽  
pp. 1399-1403 ◽  
Author(s):  
Martin Kavaliers
Keyword(s):  
Locomotor Activity ◽  
Circadian Rhythms ◽  
Social Organization ◽  
Constant Darkness ◽  
White Sucker ◽  
Circadian Period ◽  
Circadian Activity ◽  
Catostomus Commersoni ◽  
Free Running ◽  
Precise Version

Individual and shoaling white suckers, Catostomus commersoni, displayed free running circadian rhythms of locomotor activity under conditions of constant darkness and temperature. The circadian activity of shoals was different from that of single fish. The activity of single fish was rhythmic initially with a period of less than 24 h, but became arrhythmic after 15–30 days. Shoals of white suckers had a less variable circadian period that was greater than 24 h, and showed no evidence of arrhythmicity. The circadian activity of shoals is determined by its behavioural and social organization; it is not simply a more precise version of the activity of single fish.

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