Endogenous ultradian rhythms in rats exposed to prolonged continuous light

1978 ◽  
Vol 235 (5) ◽  
pp. R250-R256 ◽  
Author(s):  
K. I. Honma ◽  
T. Hiroshige
Keyword(s):  
Circadian Rhythm ◽  
Locomotor Activity ◽  
Body Temperature ◽  
Circadian Rhythms ◽  
Continuous Light ◽  
Plasma Corticosterone ◽  
Ultradian Rhythm ◽  
Ultradian Rhythms ◽  
Serial Sampling ◽  
Free Running

Circadian rhythms of locomotor activity, body temperature, and plasma corticosterone were determined simultaneously in individual rats that were exposed to 200 lx continuous light for over 3 mo. Free-running circadian rhythms of locomotor activity persisted for about 2 mo under continuous light and then the rhythms gradually decomposed. After 3 mo of exposure, circadian rhythms disappeared and activity bursts of 1- to 2-h duration manifested themselves several times during a 24-h period. Body temperature also exhibited several bursts of fluctuation and these bursts were closely correlated in their temporal sequence with those of locomotor activity. A least-squares spectrum analysis revealed that the burst had regular 4- to 6-h periods. Plasma corticosterone, determined by serial sampling at 2-h intervals from individual rats, also exhibited several secretion episodes in a day. These episodic secretions synchronized with bursts of locomotor activity. These results suggest that the ultradian component, manifested under prolonged continuous light, is a fundamental unit of the circadian rhythm and an oscillator for the ultradian rhythm is common to the three functions examined.

Internal synchronization among several circadian rhythms in rats under constant light

1978 ◽  
Vol 235 (5) ◽  
pp. R243-R249 ◽  
Author(s):  
K. I. Honma ◽  
T. Hiroshige
Keyword(s):  
Locomotor Activity ◽  
Body Temperature ◽  
Circadian Rhythms ◽  
Continuous Light ◽  
Biological Rhythms ◽  
Plasma Corticosterone ◽  
Dark Cycle ◽  
Internal Oscillator ◽  
Free Running ◽  
Phase Angles

Three biological rhythms (locomotor activity, body temperature, and plasma corticosterone) were measured simultaneously in individual rats under light-dark cycles and continuous light. Spontaneous locomotor activity was recorded on an Animex and body temperature was telemetrically monitored throughout the experiments. Blood samples were obtained serially at 2-h intervals on the experimental days. Phase angles of these rhythms were calculated by a least-squares spectrum analysis. Under light-dark cycles, the acrophases of locomotor activity, body temperature, and plasma corticosterone were found at 0029, 0106, and 1940 h, respectively. When rats were exposed to 200 lx continuous light, locomotor activity and body temperature showed free-running rhythms with a period of 25.2 h on the average. Plasma corticosterone levels determined at 12 days after exposure to continuous light exhibited a circadian rhythm with the acrophase shifted to 0720. The acrophases of locomotor activity and body temperature, determined simultaneously on the same day, were found to be located at 1303 and 1358 h, respectively. Phase-angle differences among the three rhythms on the 12th day of continuous light were essentially the same with those under the light-dark cycle. These results suggest that circadian rhythms of locomotor activity, body temperature, and plasma corticosterone are most probably coupled to a common internal oscillator in the rat.

Light-induced suppression of the rat circadian system

1995 ◽  
Vol 268 (5) ◽  
pp. R1111-R1116 ◽  
Author(s):  
P. Depres-Brummer ◽  
F. Levi ◽  
G. Metzger ◽  
Y. Touitou
Keyword(s):  
Locomotor Activity ◽  
Body Temperature ◽  
Circadian Rhythms ◽  
Prolonged Exposure ◽  
Light Exposure ◽  
Continuous Light ◽  
Circadian System ◽  
Short Exposure ◽  
Complete Suppression ◽  
Continuous Darkness

In a constant environment, circadian rhythms persist with slightly altered period lengths. Results of studies with continuous light exposure are less clear, because of short exposure durations and single-variable monitoring. This study sought to characterize properties of the oscillator(s) controlling the rat's circadian system by monitoring both body temperature and locomotor activity. We observed that prolonged exposure of male Sprague-Dawley rats to continuous light (LL) systematically induced complete suppression of body temperature and locomotor activity circadian rhythms and their replacement by ultradian rhythms. This was preceded by a transient loss of coupling between both functions. Continuous darkness (DD) restored circadian synchronization of temperature and activity circadian rhythms within 1 wk. The absence of circadian rhythms in LL coincided with a mean sixfold decrease in plasma melatonin and a marked dampening but no abolition of its circadian rhythmicity. Restoration of temperature and activity circadian rhythms in DD was associated with normalization of melatonin rhythm. These results demonstrated a transient internal desynchronization of two simultaneously monitored functions in the rat and suggested the existence of two or more circadian oscillators. Such a hypothesis was further strengthened by the observation of a circadian rhythm in melatonin, despite complete suppression of body temperature and locomotor activity rhythms. This rat model should be useful for investigating the physiology of the circadian timing system as well as to identify agents and schedules having specific pharmacological actions on this system.

scholarly journals Magnetic fluctuations affect circadian patterns of locomotor activity in zebrafish

2021 ◽  
Author(s):  
Viacheslav V. Krylov ◽  
Evgeny I. Izvekov ◽  
Vera V. Pavlova ◽  
Natalia A. Pankova ◽  
Elena A. Osipova
Keyword(s):  
Magnetic Field ◽  
Circadian Rhythm ◽  
Locomotor Activity ◽  
Circadian Rhythms ◽  
Danio Rerio ◽  
Magnetic Fluctuations ◽  
Constant Illumination ◽  
Free Running ◽  
Circadian Patterns

AbstractThe locomotor activity of zebrafish (Danio rerio) has a pronounced, well-studied circadian rhythm. Under constant illumination, the period of free-running locomotor activity in this species usually becomes less than 24 hours. To evaluate the entraining capabilities of slow magnetic variations, zebrafish locomotor activity was evaluated at constant illumination and fluctuating magnetic field with a period of 26.8 hours. Lomb-Scargle periodogram revealed significant free-running rhythms of locomotor activity and related behavioral endpoints with a period close to 27 hours. Obtained results reveal the potential of slow magnetic fluctuations for entrainment of the circadian rhythms in zebrafish. The putative mechanisms responsible for the entrainment are discussed, including the possible role of cryptochromes.

Circadian rhythms of rabbits during restrictive feeding

1987 ◽  
Vol 253 (1) ◽  
pp. R46-R54 ◽  
Author(s):  
B. Jilge ◽  
H. Hornicke ◽  
H. Stahle
Keyword(s):  
Circadian Rhythm ◽  
Locomotor Activity ◽  
Circadian Rhythms ◽  
Food Access ◽  
Feeding Time ◽  
Restricted Feeding ◽  
Small Component ◽  
Physiological Functions ◽  
System A ◽  
Free Running

Without a zeitgeber the circadian rhythms of five physiological functions free-ran with a period length greater than 24 h. Restricted feeding time (RF) masked the free-running rhythms. In addition to masking, entrainment with RF occurred. This process was most evident in locomotor activity and visits to the food box. RF thus had zeitgeber properties in these rabbits. However, in most rabbits the RF zeitgeber was not strong enough to entrain the circadian rhythm completely. A small component free-ran during RF. Following return to continuous food access the whole circadian rhythm resumed to free-run again. In some animals its phase was determined by the RF zeitgeber and in others by the small free-running fraction present during RF. The results suggest that in addition to the light-dark-entrainable circadian oscillator system a feeding-entrainable oscillator exists that takes over phase control of the majority of the rhythm during RF.

Free-Running Human Circadian Rhythms in Svalbard

1979 ◽  
Vol 34 (5-6) ◽  
pp. 470-473 ◽  
Author(s):  
A. Johnsson ◽  
W. Engelmann ◽  
W. Klemke ◽  
Aud Tveito Ekse
Keyword(s):  
Body Temperature ◽  
Circadian Rhythms ◽  
Continuous Light ◽  
Circadian System ◽  
The Body ◽  
The Arctic ◽  
Light Conditions ◽  
Temperature Recording ◽  
Rest Time ◽  
Free Running

Abstract The body temperature, activity-rest time, electrolytes of urine samples and mood was measured in two persons during a 19 day period under continuous light conditions in the arctic (vicinity of Ny Ålesund, Svalbard-Spitsbergen). For temperature recording a new thermoprobe and a portable printer was used. Possible week Zeitgeber of the 24 hour day did not synchronize the circadian system, since circadian rhythms of about 26 hours were found. These results open up the pos­ sibility to study effects of drugs on the circadian system of humans under Svalbard conditions.

Hormonal and locomotor activity rhythms in rats under 90-min dark-pulse conditions

1993 ◽  
Vol 264 (6) ◽  
pp. R1058-R1064
Author(s):  
M. L. Laakso ◽  
T. Porkka-Heiskanen ◽  
L. Leinonen ◽  
S. L. Joutsiniemi ◽  
P. T. Mannisto
Keyword(s):  
Circadian Rhythm ◽  
Locomotor Activity ◽  
Circadian Rhythms ◽  
Serum Levels ◽  
Thyroid Stimulating Hormone ◽  
Diurnal Variations ◽  
Serum Corticosterone ◽  
Pineal Melatonin ◽  
Free Running ◽  
Dark Pulse

The ability of a short dark pulse to entrain the circadian rhythms in rats was investigated. Pineal melatonin contents and serum levels of corticosterone and thyrotropin, a thyroid-stimulating hormone (TSH), were measured and locomotor activity was recorded under 12:12-h light-dark cycles (LD; darkness from 1800 to 0600 h) and under a 22.5:1.5 h LD lighting schedule (darkness from 1800 to 1930 h). The 90-min dark pulse was enough to trigger the rise of melatonin synthesis, but a free-running component was detected in the locomotor activity. Corticosterone levels showed diurnal variations under both conditions. The decrease of corticosterone and the increase of melatonin were phase locked, but the corticosterone pattern was distorted under the dark-pulse conditions. The 24-h rhythm of TSH was detectable in the control but not in the dark-pulse schedule. The results suggest that the circadian rhythm of pineal melatonin and the decrease of serum corticosterone levels were entrainable by the dark pulses, whereas the increase of corticosterone, the variations of TSH, and the rhythm of locomotor activity were not.

scholarly journals Entrainment of circadian rhythms of locomotor activity by ambient temperature cycles in the dromedary camel

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Hicham Farsi ◽  
Mohamed R. Achaâban ◽  
Mohammed Piro ◽  
Béatrice Bothorel ◽  
Mohammed Ouassat ◽  
...  
Keyword(s):  
Locomotor Activity ◽  
Body Temperature ◽  
Circadian Rhythms ◽  
Ambient Temperature ◽  
Cycle Phase ◽  
Dromedary Camel ◽  
Dark Cycle ◽  
Free Running ◽  
Activity Onset ◽  
Master Clock

Abstract In the dromedary camel, a well-adapted desert mammal, daily ambient temperature (Ta)-cycles have been shown to synchronize the central circadian clock. Such entrainment has been demonstrated by examining two circadian outputs, body temperature and melatonin rhythms. Locomotor activity (LA), another circadian output not yet investigated in the camel, may provide further information on such specific entrainment. To verify if daily LA is an endogenous rhythm and whether the desert Ta-cycle can entrain it, six dromedaries were first kept under total darkness and constant-Ta. Results showed that the LA rhythm free runs with a period of 24.8–24.9 h. After having verified that the light–dark cycle synchronizes LA, camels were subjected to a Ta-cycle with warmer temperatures during subjective days and cooler temperatures during subjective nights. Results showed that the free-running LA rhythm was entrained by the Ta-cycle with a period of exactly 24.0 h, while a 12 h Ta-cycle phase advance induced an inversion of the LA rhythm and advanced the acrophase by 9 h. Similarly, activity onset and offset were significantly advanced. All together, these results demonstrate that the Ta-cycle is a strong zeitgeber, able to entrain the camel LA rhythm, hence corroborating previous results concerning the Ta non-photic synchronization of the circadian master clock.

scholarly journals Amplitude of circadian rhythms becomes weaker in the north, but there is no cline in the period of rhythm in a beetle

2020 ◽  
Author(s):  
Masato S. Abe ◽  
Kentarou Matsumura ◽  
Taishi Yoshii ◽  
Takahisa Miyatake
Keyword(s):  
Circadian Rhythm ◽  
Locomotor Activity ◽  
Circadian Rhythms ◽  
Large Sample Size ◽  
Pest Species ◽  
Biological Clocks ◽  
The North ◽  
Stored Product Pest ◽  
Free Running ◽  
Taxonomic Groups

AbstractMany species show rhythmicity in activity, from the timing of flowering in plants to that of foraging behaviour in animals. The free-running periods and amplitude (sometimes called strength or power) of circadian rhythms are often used as indicators of biological clocks. Many reports have shown that these traits highly geographically variable, and interestingly, they often show latitudinal or altitudinal clines. In many cases, the higher the latitude is, the longer the free-running circadian period (i.e., period of rhythm) in insects and plants. However, reports of positive correlations between latitude or longitude and circadian rhythm traits, including free-running periods, the power of the rhythm and locomotor activity, are limited to certain taxonomic groups. Therefore, we collected a cosmopolitan stored-product pest species, the red flour beetle Tribolium castaneum, in various parts of Japan and examined its rhythm traits, including the power of the rhythm and period of the rhythm, which were calculated from locomotor activity. The analysis revealed that power was significantly lower for beetles collected in northern areas compared with southern areas in Japan. However, it is worth noting that the period of circadian rhythm did not show any clines; specifically, it did not vary among the sampling sites, despite the very large sample size (n = 1585). We discuss why these cline trends were observed in T. castaneum.

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