Circadian control of thermoregulation in the squirrel monkey, Saimiri sciureus

The characteristics and control of the circadian rhythms of core body temperature (colonic) and skin temperature (tail) were studied in chair-acclimatized squirrel monkeys (Saimiri sciureus). When animals were entrained to a light-dark cycle (12 h 600 lx; 12 h less than 1 lx) these two temperatures displayed prominent, reproducible, tightly coupled circadian rhythms. In contsant light of 600 lx, where no other effective circadian time cues were present, both temperature rhythms persisted with free-running periods. Within each animal, however, these rhythms were not as tightly coupled to one another as in LD. On occasion colonic and tail temperature rhythms free-ran with different circadian periods and some animals demonstrated "splitting" of the colonic temperature rhythm, with the colonic temperature rhythm displaying a bimodal pattern. These results suggest that the circadian rhythm of body temperature in primates is under the control of more than one potentially independent circadian oscillator.

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Comparison of synchronization of primate circadian rhythms by light and food

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.1978.234.3.r130 ◽

1978 ◽

Vol 234 (3) ◽

pp. R130-R135 ◽

Cited By ~ 1

Author(s):

F. M. Sulzman ◽

C. A. Fuller ◽

M. C. Moore-Ede

Keyword(s):

Circadian Rhythms ◽

Phase Delay ◽

Saimiri Sciureus ◽

Published Data ◽

Water Excretion ◽

Temporal Cues ◽

Temperature Rhythm ◽

Urinary Potassium ◽

Temperature Rhythms ◽

Colonic Temperature

Several circadian rhythms in squirrel monkeys (Saimiri sciureus) entrained by two different agents were studied to compare their mode of coupling with the environmental zeitgebers. Synchronization was accomplished either by light-dark cycles consisting of 12 h of 600 lx followed by 12 h of less than 1 lx (LD 12:12), or by eat-fast cycles in which the animals could eat for 3 h and then had to fast for the remaining 21 h each day (EF 3:21). The rhythms of drinking, colonic temperature, and urinary potassium and water excretion were measured in chair-acclimatized monkeys. The drinking and urinary rhythms were more reproducible (smaller mean variance) and more stable (smaller standard deviation of the timing of a phase reference point) in EF than in LD cycles, whereas the temperature rhythm was more tightly controlled by LD cycles than by EF cycles. In constant light an 8-h phase delay in the EF cycle caused the drinking and urinary rhythms to resynchronize to the EF cycle within one day, while the temperature rhythm required about 6 days to resynchronize. In contrast, previously published data for a similar phase delay in the LD cycle with food available ad libitum show that the drinking and temperature rhythms resynchronized more rapidly than the urinary rhythms. These results indicate that separate mechanisms are involved in transducing temporal cues from LD and EF cycles in the circadian timekeeping system of these nonhuman primates.

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Significance of circadian rhythms in severely brain-injured patients

Neurology ◽

10.1212/wnl.0000000000003942 ◽

2017 ◽

Vol 88 (20) ◽

pp. 1933-1941 ◽

Cited By ~ 22

Author(s):

Christine Blume ◽

Julia Lechinger ◽

Nayantara Santhi ◽

Renata del Giudice ◽

Maria-Teresa Gnjezda ◽

...

Keyword(s):

Body Temperature ◽

Circadian Rhythms ◽

Vegetative State ◽

Minimally Conscious State ◽

Bright Light ◽

Circadian Rhythmicity ◽

Cross Sectional ◽

Temperature Rhythm ◽

Temperature Rhythms ◽

The Relationship

Objective:To investigate the relationship between the presence of a circadian body temperature rhythm and behaviorally assessed consciousness levels in patients with disorders of consciousness (DOC; i.e., vegetative state/unresponsive wakefulness syndrome or minimally conscious state).Methods:In a cross-sectional study, we investigated the presence of circadian temperature rhythms across 6 to 7 days using external skin temperature sensors in 18 patients with DOC. Beyond this, we examined the relationship between behaviorally assessed consciousness levels and circadian rhythmicity.Results:Analyses with Lomb-Scargle periodograms revealed significant circadian rhythmicity in all patients (range 23.5–26.3 hours). We found that especially scores on the arousal subscale of the Coma Recovery Scale–Revised were closely linked to the integrity of circadian variations in body temperature. Finally, we piloted whether bright light stimulation could boost circadian rhythmicity and found positive evidence in 2 out of 8 patients.Conclusion:The study provides evidence for an association between circadian body temperature rhythms and arousal as a necessary precondition for consciousness. Our findings also make a case for circadian rhythms as a target for treatment as well as the application of diagnostic and therapeutic means at times when cognitive performance is expected to peak.

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Circadian rhythm dissociation in an environment with conflicting temporal information

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.1978.235.3.r175 ◽

1978 ◽

Vol 235 (3) ◽

pp. R175-R180 ◽

Cited By ~ 1

Author(s):

F. M. Sulzman ◽

C. A. Fuller ◽

L. G. Hiles ◽

M. C. Moore-Ede

Keyword(s):

Urine Volume ◽

Squirrel Monkeys ◽

Light Period ◽

Temporal Information ◽

Saimiri Sciureus ◽

Potassium Excretion ◽

Temperature Rhythm ◽

Circadian Time ◽

Urinary Potassium ◽

Colonic Temperature

The relative contributions of light-dark (LD) cycles and feeding (EF) cycles in providing temporal information to the circadian time-keeping system were examined in chair-acclimatized squirrel monkeys (Saimiri sciureus). The circadian rhythms of drinking, colonic temperature, urine volume, and urinary potassium excretion were measured with the LD and EF cycles providing either conflicting phases or periods. In conflicting phase experiments, animals were exposed to 24-h LD cycles consisting of 12 h of 600 lx followed by 12 h of less than 1 ls and concurrent 24-h EF cycles in which the animals ate for 3 h and then fasted for 21 h. One group had food available at the beginning and a second group at the end of the light period. In conflicting period experiments, monkeys were exposed to 23-h LD cycles (LD 11.5:11.5) and 24-h EF cycles (EF 3:21). Analysis of the rhythms showed that both phase and period information were conveyed to the drinking and urinary rhythms by the EF cycle, and to the temperature rhythm by the LD cycle.

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Circadian rhythm of body temperature persists after suprachiasmatic lesions in the squirrel monkey

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.1981.241.5.r385 ◽

1981 ◽

Vol 241 (5) ◽

pp. R385-R391 ◽

Cited By ~ 2

Author(s):

C. A. Fuller ◽

R. Lydic ◽

F. M. Sulzman ◽

H. E. Albers ◽

B. Tepper ◽

...

Keyword(s):

Circadian Rhythm ◽

Body Temperature ◽

Squirrel Monkey ◽

Core Body Temperature ◽

Drinking Behavior ◽

Spectral Component ◽

Saimiri Sciureus ◽

Physiological Variables ◽

Temperature Rhythm ◽

Core Body

Squirrel monkeys (Saimiri sciureus) demonstrate prominent circadian (approx 24 h) rhythms in many behavioral and physiological variables including drinking and body temperature. Both of these rhythms can be entrained by a 24-h light-dark cycle (LD 12:12) but will free-run with an endogenous period in a constantly illuminated (LL:600 lx) environment free of time cues. After radio-frequency lesions were placed stereotaxically in the suprachiasmatic nuclei (SCN) of five monkeys, the circadian rhythm of drinking behavior was disrupted when the monkeys were maintained in LL. However, the circadian rhythm in core body temperature in these animals persisted in LL with a significant circadian spectral component following destruction of the SCN. The SCN thus appear to be of fundamental importance for regulating the circadian organization of drinking; however, an oscillator located elsewhere in the squirrel monkey is capable of generating the core body temperature rhythm.

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Circadian temperature rhythms in rabbit pups and in their does

Laboratory Animals ◽

10.1258/0023677011911831 ◽

2001 ◽

Vol 35 (4) ◽

pp. 364-373 ◽

Cited By ~ 35

Author(s):

B. Jilge ◽

B. Kuhnt ◽

W. Landerer ◽

S. Rest

Keyword(s):

Body Temperature ◽

Core Body Temperature ◽

Circadian Oscillator ◽

Suprachiasmatic Nuclei ◽

The Core ◽

Temperature Rhythm ◽

Pregnancy And Lactation ◽

Temperature Rhythms ◽

Milk Ingestion ◽

Core Body

Circadian rhythms of mammals are generated endogenously, the master oscillator system residing in the suprachiasmatic nuclei (SCN). Previous experiments have indicated that the rabbit has a feeding entrainable circadian oscillator (FEO) which is supposed to be of greatest importance during the early infancy of the rabbit. Here we report the course of telemetrically monitored core body temperature of rabbit pups and of their does. Temperature increased from 37.6 ± 0.3 °C on day 2 to 39.5 ± 0.1 °C on day 28 of life. The pups showed a 24 h temperature rhythm even during their first days of life. Temperature increased 2½-3 h prior to nursing for 0.4-0.8 °C and rose for an additional 0.4-0.6 °C immediately after milk ingestion. The anticipatory, but not the postprandial component persisted when nursing was skipped twice. The persistence of a rhythm in the absence of any entraining agent is crucial for its endogenous generation. In the doe, the core body temperature gradually decreased during the last 2/3 of pregnancy. During parturition it steeply rose for 1.5-1.7 °C and attained a plateau of 39.7 ± 0.2 °C during lactation. The circadian rhythm persisted during the whole course of pregnancy and lactation. Thus, in the rabbit an endogenous, feeding entrainable circadian oscillator appears to operate from the first days of life. It is of functional significance in that it alerts the pup in time so that it is able to utilize the singular short presence of the doe for maximal milk intake.

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Nonphotic entrainment of the human circadian pacemaker

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.1998.274.4.r991 ◽

1998 ◽

Vol 274 (4) ◽

pp. R991-R996 ◽

Cited By ~ 32

Author(s):

Elizabeth B. Klerman ◽

David W. Rimmer ◽

Derk-Jan Dijk ◽

Richard E. Kronauer ◽

Joseph F. Rizzo ◽

...

Keyword(s):

Circadian Rhythms ◽

Light Exposure ◽

Core Body Temperature ◽

Biological Clock ◽

Bright Light ◽

Circadian Pacemaker ◽

Temperature Rhythms ◽

Blind Individuals ◽

Nonphotic Entrainment ◽

Core Body

In organisms as diverse as single-celled algae and humans, light is the primary stimulus mediating entrainment of the circadian biological clock. Reports that some totally blind individuals appear entrained to the 24-h day have suggested that nonphotic stimuli may also be effective circadian synchronizers in humans, although the nonphotic stimuli are probably comparatively weak synchronizers, because the circadian rhythms of many totally blind individuals “free run” even when they maintain a 24-h activity-rest schedule. To investigate entrainment by nonphotic synchronizers, we studied the endogenous circadian melatonin and core body temperature rhythms of 15 totally blind subjects who lacked conscious light perception and exhibited no suppression of plasma melatonin in response to ocular bright-light exposure. Nine of these fifteen blind individuals were able to maintain synchronization to the 24-h day, albeit often at an atypical phase angle of entrainment. Nonphotic stimuli also synchronized the endogenous circadian rhythms of a totally blind individual to a non-24-h schedule while living in constant near darkness. We conclude that nonphotic stimuli can entrain the human circadian pacemaker in some individuals lacking ocular circadian photoreception.

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