Daily hypothermia and torpor in a tropical primate: synchronization by 24-h light-dark cycle

2001 ◽  
Vol 281 (6) ◽  
pp. R1925-R1933 ◽  
Author(s):  
M. Perret ◽  
F. Aujard
Keyword(s):  
Locomotor Activity ◽  
Fixed Time ◽  
Temporal Organization ◽  
Physiological Changes ◽  
Dark Cycle ◽  
Subjective Night ◽  
Free Running ◽  
Rapid Drop ◽  
Gray Mouse Lemur ◽  
Short Days

To study the temporal organization of daily hypothermia and torpor in a nocturnal Malagasy primate, the gray mouse lemur, body temperature (Tb) and locomotor activity were recorded using telemetry on 39 males held in 24-h light-dark cycles of different photoperiods. Under free-running condition, the circadian Tb and locomotor activity rhythms had a period shorter than 24 h. Circadian daily hypothermia started by a rapid drop in Tb (0.24°C/10 min) at the end of subjective night (13 h 25 ± 20 min) and was characterized by minimal Tb values 3 h 20 ± 5 min later. Spontaneous arousal from daily hypothermia occurred at a fixed time (6 h 05 ± 15 min, n = 7) after the beginning of subjective day. In animals exposed to 24-h light-dark cycles with night duration varying from 10 to 14 h, locomotor activity was strictly restricted to dark time, but the temporal organization of daily hypothermia was not modified, although changes in amplitude of Tb rhythm were observed. Daily hypothermia was directly induced by light and lasted 5 h 10 ± 10 min, with minimal Tb values 3 h 30 ± 30 min ( n = 28) after lights on, on condition that nighttime did not exceed the duration of subjective night. However, in animals exposed to 24-h light-dark cycles with night duration varying from 10 to 5 h, the limit of induction of daily hypothermia by light was ∼9 h after the beginning of night. Finally, under short days (14:10-h light-dark cycle), long bouts (6 h 50 ± 40 min) of actual torpor (minimum Tb 27.6 ± 0.9°C) were observed and would involve mechanisms depending on physiological changes induced by short day exposure.

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.

Entrainment in calorie-restricted mice: conflicting zeitgebers and free-running conditions

1998 ◽  
Vol 274 (6) ◽  
pp. R1751-R1761 ◽  
Author(s):  
Etienne Challet ◽  
Leah C. Solberg ◽  
Fred W. Turek
Keyword(s):  
Locomotor Activity ◽  
Calorie Restriction ◽  
Phase Advance ◽  
Constant Darkness ◽  
Dark Cycle ◽  
Subjective Night ◽  
Ad Libitum ◽  
Anticipatory Activity ◽  
Time Of Feeding ◽  
Nocturnal Period

Phase-shifting effects of timed calorie restriction were investigated in mice during exposure to a 12:12-h light-dark cycle. Food-anticipatory activity (FAA), the output of a food-entrainable pacemaker, was expressed before the time of feeding whether mice received daily hypocaloric food (3.3 g of chow/day) or normocaloric food (5 g of chow/day) at zeitgeber time (ZT) 2 (ZT12 = lights off). Subsequently, mice were placed in constant darkness and fed ad libitum. The onset of the nocturnal period of locomotor activity was phase advanced by 1 h in calorie-restricted mice compared with normocalorie-fed controls. The phase advance still occurred when FAA was prevented by restraining calorie-restricted mice. Giving hypocaloric food at ZT2, ZT10, ZT14, or ZT22 phase advanced the nocturnal pattern of activity by 1, 3, 1, and 1 h, respectively. After transfer to constant darkness, FAA free ran in parallel with the normal nocturnal period of locomotor activity. A light pulse during the early subjective night phase delayed both components. These results indicate that 1) timed calorie restriction under a light-dark cycle can phase advance the light-entrainable pacemaker with a phase-dependent magnitude, 2) FAA feedback is not crucial for the observed phase advance, and 3) the light-entrainable pacemaker may control the period of the food-entrainable pacemaker in mice fed ad libitum.

scholarly journals Locomotor activity in the Namaqua rock mouse (Micaelamys namaquensis): entrainment by light manipulations

2014 ◽  
Vol 92 (12) ◽  
pp. 1083-1091 ◽  
Author(s):  
I. van der Merwe ◽  
N.C. Bennett ◽  
A. Haim ◽  
M.K. Oosthuizen
Keyword(s):  
Locomotor Activity ◽  
Activity Rhythm ◽  
Light Cycle ◽  
Nocturnal Activity ◽  
Dark Cycle ◽  
Subjective Night ◽  
Activity Onset ◽  
Role Of Light ◽  
Constant Dark

The locomotor activity rhythms of wild-caught Namaqua rock mice (Micaelamys namaquensis (A. Smith, 1834)) were examined under four light-cycle regimes to quantitatively describe the daily expression of locomotor activity and to study the innate relationship between activity and the light–dark cycle. Activity was always significantly higher at night than during the day; we note four trends. (1) The LD1 light cycle (12 h light : 12 h dark) established a distinct light-entrained and strongly nocturnal activity rhythm (99.11% nocturnal activity). The activity onset was prompt (zeitgeber time (ZT) 12.2 ± 0.04) and activity continued without any prominent peaks or extended times of rest until the offset of activity at ZT 23.73 ± 0.08. (2) Evidence for the internal maintenance of locomotor activity was obtained from the constant dark cycle (DD) in which locomotor activity free ran (mean τ = 23.89 h) and 77.58% of the activity was expressed during the subjective night. (3) During re-entrainment (LD2; 12 h light : 12 h dark), a nocturnal activity rhythm was re-established (98.65% nocturnal activity). (4) The inversion of the light cycle (DL; 12 h dark : 12 h light) evoked a shift in activity that again revealed dark-induced locomotor activity (95.69% nocturnal activity). Females were consistently more active than males in all of the light cycles, but only under the DD and LD2 cycles were females significantly more active than males. Although this species is considered nocturnal from field observations, information regarding its daily expression of activity and the role of light in its entrainment is lacking. To the best of our knowledge, this study is the first to report quantitatively on the species’ daily rhythm of activity and to investigate its relationship to the light–dark cycle.

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 Effects of the colour of photophase light on locomotor activity in a nocturnal and a diurnal South African rodent

2019 ◽  
Vol 15 (10) ◽  
pp. 20190597 ◽  
Author(s):  
Ingrid van der Merwe ◽  
Nigel C. Bennett ◽  
Abraham Haim ◽  
Maria K. Oosthuizen
Keyword(s):  
Locomotor Activity ◽  
South African ◽  
Temporal Organization ◽  
Dark Cycle ◽  
Long Wavelength ◽  
Rhabdomys Pumilio ◽  
Nocturnal Species ◽  
Wavelength Light ◽  
Diurnal Species ◽  
Effect Of Light

Many physiological and behavioural responses to varying qualities of light, particularly during the night (scotophase), have been well documented in rodents. We used varying wavelengths of day-time (photophase) lighting to assess daily responses in locomotor activity in the nocturnal Namaqua rock mouse ( Micaelamys namaquensis ) and diurnal four-striped field mouse ( Rhabdomys pumilio ). Animals were exposed to three light–dark cycle regimes: a short-wavelength- (SWLC, blue), a medium-wavelength- (MWLC, green) and a long-wavelength light–dark cycle (LWLC, red). Overall, daily locomotor activity of both species changed according to different wavelengths of light: the diurnal species displayed most activity under the SWLC and the nocturnal species exhibited the highest levels of activity under the LWLC. Both species showed an increase in diurnal activity and a decrease in nocturnal activity under the LWLC. These results indicate an attenuated responsiveness to long-wavelength light in the nocturnal species, but this does not appear to be true for the diurnal species. These results emphasize that the effect of light on the locomotor activity of animals depends on both the properties of the light and the temporal organization of activity of a species.

scholarly journals The Cell Division Cycle of Euglena gracilis Indicates That the Level of Circadian Plasticity to the External Light Regime Changes in Prolonged-Stationary Cultures

Plants ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 1475
Author(s):  
Shota Kato ◽  
Hong Gil Nam
Keyword(s):  
Cell Division ◽  
Circadian Rhythms ◽  
Euglena Gracilis ◽  
Cell Cycle Progression ◽  
Light Signal ◽  
Cell Division Cycle ◽  
Regime Changes ◽  
Fitness Advantage ◽  
Subjective Night ◽  
Free Running

In unicellular photosynthetic organisms, circadian rhythm is tightly linked to gating of cell cycle progression, and is entrained by light signal. As several organisms obtain a fitness advantage when the external light/dark cycle matches their endogenous period, and aging alters circadian rhythms, senescence phenotypes of the microalga Euglena gracilis of different culture ages were characterized with respect to the cell division cycle. We report here the effects of prolonged-stationary-phase conditions on the cell division cycles of E. gracilis under non-24-h light/dark cycles (T-cycles). Under T-cycles, cells established from 1-month-old and 2-month-old cultures produced lower cell concentrations after cultivation in the fresh medium than cells from 1-week-old culture. This decrease was not due to higher concentrations of dead cells in the populations, suggesting that cells of different culture ages differ in their capacity for cell division. Cells from 1-week-old cultures had a shorter circadian period of their cell division cycle under shortened T-cycles than aged cells. When algae were transferred to free-running conditions after entrainment to shortened T-cycles, the young cells showed the peak growth rate at a time corresponding to the first subjective night, but the aged cells did not. This suggests that circadian rhythms are more plastic in younger E. gracilis cells.

Central and Peripheral Clock Control of Circadian Feeding Rhythms

2021 ◽  
pp. 074873042110458
Author(s):  
Carson V. Fulgham ◽  
Austin P. Dreyer ◽  
Anita Nasseri ◽  
Asia N. Miller ◽  
Jacob Love ◽  
...  
Keyword(s):  
Locomotor Activity ◽  
Circadian Clock ◽  
Feeding Behavior ◽  
Molecular Clock ◽  
Fat Body ◽  
Molecular Clocks ◽  
Central Brain ◽  
Feeding Rhythms ◽  
Free Running ◽  
The Brain

Many behaviors exhibit ~24-h oscillations under control of an endogenous circadian timing system that tracks time of day via a molecular circadian clock. In the fruit fly, Drosophila melanogaster, most circadian research has focused on the generation of locomotor activity rhythms, but a fundamental question is how the circadian clock orchestrates multiple distinct behavioral outputs. Here, we have investigated the cells and circuits mediating circadian control of feeding behavior. Using an array of genetic tools, we show that, as is the case for locomotor activity rhythms, the presence of feeding rhythms requires molecular clock function in the ventrolateral clock neurons of the central brain. We further demonstrate that the speed of molecular clock oscillations in these neurons dictates the free-running period length of feeding rhythms. In contrast to the effects observed with central clock cell manipulations, we show that genetic abrogation of the molecular clock in the fat body, a peripheral metabolic tissue, is without effect on feeding behavior. Interestingly, we find that molecular clocks in the brain and fat body of control flies gradually grow out of phase with one another under free-running conditions, likely due to a long endogenous period of the fat body clock. Under these conditions, the period of feeding rhythms tracks with molecular oscillations in central brain clock cells, consistent with a primary role of the brain clock in dictating the timing of feeding behavior. Finally, despite a lack of effect of fat body selective manipulations, we find that flies with simultaneous disruption of molecular clocks in multiple peripheral tissues (but with intact central clocks) exhibit decreased feeding rhythm strength and reduced overall food intake. We conclude that both central and peripheral clocks contribute to the regulation of feeding rhythms, with a particularly dominant, pacemaker role for specific populations of central brain clock cells.

scholarly journals Effects of photoperiod on daily locomotor activity, energy expenditure, and feeding behavior in a seasonal mammal

2010 ◽  
Vol 298 (5) ◽  
pp. R1409-R1416 ◽  
Author(s):  
Amy Warner ◽  
Preeti H. Jethwa ◽  
Catherine A. Wyse ◽  
Helen I'Anson ◽  
John M. Brameld ◽  
...  
Keyword(s):  
Body Weight ◽  
Locomotor Activity ◽  
Energy Expenditure ◽  
Feeding Behavior ◽  
Heat Production ◽  
Prolonged Exposure ◽  
Dark Phase ◽  
Daily Rhythms ◽  
Dark Cycle ◽  
Activity Energy

The objective of this study was to determine whether the previously observed effects of photoperiod on body weight in Siberian hamsters were due to changes in the daily patterns of locomotor activity, energy expenditure, and/or feeding behavior. Adult males were monitored through a seasonal cycle using an automated comprehensive laboratory animal monitoring system (CLAMS). Exposure to a short-day photoperiod (SD; 8:16-h light-dark cycle) induced a significant decline in body weight, and oxygen consumption (V̇o2), carbon dioxide production (V̇co2), and heat production all decreased reaching a nadir by 16 wk of SD. Clear daily rhythms in locomotor activity, V̇o2, and V̇co2 were observed at the start of the study, but these all progressively diminished after prolonged exposure to SD. Rhythms in feeding behavior were also detected initially, reflecting an increase in meal frequency but not duration during the dark phase. This rhythm was lost by 8 wk of SD exposure such that food intake was relatively constant across dark and light phases. After 18 wk in SD, hamsters were transferred to a long-day photoperiod (LD; 16:8-h light-dark cycle), which induced significant weight gain. This was associated with an increase in energy intake within 2 wk, while V̇o2, V̇co2, and heat production all increased back to basal levels. Rhythmicity was reestablished within 4 wk of reexposure to long days. These results demonstrate that photoperiod impacts on body weight via complex changes in locomotor activity, energy expenditure, and feeding behavior, with a striking loss of daily rhythms during SD exposure.

scholarly journals Drugs of Abuse Can Entrain Circadian Rhythms

2007 ◽  
Vol 7 ◽  
pp. 203-212 ◽  
Author(s):  
Ann E. K. Kosobud ◽  
Andrea G. Gillman ◽  
Joseph K. Leffel ◽  
Norman C. Pecoraro ◽  
G. V. Rebec ◽  
...  
Keyword(s):  
Locomotor Activity ◽  
Circadian Rhythms ◽  
Drug Metabolism ◽  
Suprachiasmatic Nucleus ◽  
Drugs Of Abuse ◽  
Social Cues ◽  
Dark Cycle ◽  
Drug Reward ◽  
Locomotor Stimulation ◽  
Almost All

Circadian rhythms prepare organisms for predictable events during the Earth's 24-h day. These rhythms are entrained by a variety of stimuli. Light is the most ubiquitous and best known zeitgeber, but a number of others have been identified, including food, social cues, locomotor activity, and, most recently drugs of abuse. Given the diversity of zeitgebers, it is probably not surprising that genes capable of clock functions are located throughout almost all organs and tissues. Recent evidence suggests that drugs of abuse can directly entrain some circadian rhythms. We have report here that entrainment by drugs of abuse is independent of the suprachiasmatic nucleus and the light/dark cycle, is not dependent on direct locomotor stimulation, and is shared by a variety of classes of drugs of abuse. We suggest that drug-entrained rhythms reflect variations in underlying neurophysiological states. This could be the basis for known daily variations in drug metabolism, tolerance, and sensitivity to drug reward. These rhythms could also take the form of daily periods of increased motivation to seek and take drugs, and thus contribute to abuse, addiction and relapse.

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