Effects of temperature on the circadian rhythm of pig-tailed macaques Macaca nemestrina

1983 ◽  
Vol 245 (6) ◽  
pp. R800-R804 ◽  
Author(s):  
H. Tokura ◽  
J. Aschoff
Keyword(s):  
Ambient Temperature ◽  
Activity Rhythm ◽  
Mammalian Species ◽  
Bright Light ◽  
Macaca Nemestrina ◽  
Temperature Cycle ◽  
Systematic Effect ◽  
Free Running ◽  
Dim Light ◽  
Effects Of Temperature

Activity rhythms of pig-tailed macaques, Macaca nemestrina, were recorded under three different conditions: 1) constant illumination (LL) and constant ambient temperature; 2) light-dark (LD) cycles with 12 h of bright light and 12 h of dim light (LD 12:12) at constant ambient temperature; 3) cycles with 12 h of high (32 degrees C) and 12 h of low temperature (17 degrees C) in LL. In constant conditions the period of the free-running rhythm was positively correlated with light intensity. Ambient temperature had no systematic effect on the period in LL of 0.45 and 45 lx; when measured in 100 or 450 lx, the period was consistently longer at 32 than at 17 degrees C. Temperature cycles with a range of 15 degrees C resulted in entrainment in three adult animals, but not at all tests; two adults and a couple of young animals were never entrained. Entrainment by temperature was less accurate than that by LD. The results demonstrate that a temperature cycle can entrain the circadian activity rhythm of an homeothermic mammalian species but that it is a very weak zeitgeber compared with LD cycle.

Zur Beziehung zwischen Phasenlage und Spontanfrequenz bei der endogenen Tagesperiodik

1963 ◽  
Vol 18 (2) ◽  
pp. 154-157 ◽  
Author(s):  
Klaus Hoffmann
Keyword(s):  
Phase Angle ◽  
Diurnal Rhythm ◽  
Activity Rhythm ◽  
Sustained Oscillation ◽  
Temperature Cycle ◽  
Biological Processes ◽  
Experimental Demonstration ◽  
Free Running ◽  
Spontaneous Frequency ◽  
Free Running Period

The mechanism underlying the endogenous diurnal periodicity of biological processes can be considered a self-sustained oscillation, which can be entrained to an external cycle. In such oscillations the phase-angle of the entrained cycle depends upon the spontaneous frequency (free-running period) of the oscillator.The activity rhythm of lizards kept in constant light, and in a sinusoidal 24-hour temperature cycle, showed entrainment to this cycle. The phase of the entrained rhythm depended on the spontaneous frequency which was expressed in constant conditions occurring immediately before or after the exposure to the extraneous cycle. This is the first experimental demonstration showing the dependence of phase on the free-running period in an endogenous diurnal rhythm.

Dissociation of motor activity circadian rhythm in rats after exposure to LD cycles of 4-h period

1997 ◽  
Vol 272 (1) ◽  
pp. R95-R102 ◽  
Author(s):  
J. Vilaplana ◽  
T. Cambras ◽  
A. Diez-Noguera
Keyword(s):  
Motor Activity ◽  
Activity Rhythm ◽  
Bright Light ◽  
Constant Light ◽  
Constant Darkness ◽  
Circadian Oscillators ◽  
Entrainment Process ◽  
Free Running ◽  
Anticipatory Activity ◽  
Degree Of Coupling

For > 30 days Wistar rats were subjected to six dark pulses per day (T4 cycles; 3 h light, 1 h dark) to study the possibility of dissociating their motor activity rhythm into distinct circadian components. Rats of both sexes were used, one-half of which were pinealectomized to examine the effect of the pineal gland on the entrainment process. Results show that when rats were maintained under T4 a 4-h rhythm in their motor activity was present. Rats showed anticipatory activity to dark phases, suggesting that the motor activity components are actually entrained to the external light/dark (LD) cycles. When rats were left under constant darkness after T4, some motor activity components coming from the dark phases free ran for several days with different circadian periods. This suggests that the motor activity pattern is generated by several circadian oscillators. Moreover, the free-running components of motor activity after T4 were more evident when T4 was applied after exposure to constant light than after exposure to constant darkness. These results support the hypothesis that the circadian system of the rat is formed by several circadian oscillators, whose degree of coupling depends on light conditions. In constant light, bright light may inhibit internal coupling within the system, making it subsequently more susceptible to the T4 cycles. No differences were observed between pinealectomized and sham-operated animals, although females were more sensitive to T4 cycles than males.

Failure of pinealectomy or melatonin to alter circadian activity rhythm of the rat

1982 ◽  
Vol 242 (3) ◽  
pp. R261-R264 ◽  
Author(s):  
P. W. Cheung ◽  
C. E. McCormack
Keyword(s):  
Wheel Running ◽  
Activity Rhythm ◽  
Physiological Mechanism ◽  
Continuous Darkness ◽  
Running Activity ◽  
Melatonin Administration ◽  
Wheel Running Activity ◽  
Free Running ◽  
Dim Light ◽  
Free Running Period

These experiments were undertaken to determine if the pineal gland is involved in the physiological mechanism by which the rat alters its free-running period (tau) in response to changes in illuminance. Spontaneous wheel-running activity was recorded from pinealectomized or sham-operated female Charles River rats. The tau of running activity was determined in continuous darkness (DD) or in continuous dim light (LL). Pinealectomized rats and sham-operated rats lengthened their tau's to approximately the same extent when shifted from DD to LL and shortened their tau's when shifted back to DD. Continuous melatonin administration via Silastic capsules failed to alter tau of rats kept in dim LL. These results indicate that the pineal is not primarily involved in the mechanism by which the rat alters tau in response to changes in illuminance.

Effects of long-term restricted feeding on motor activity rhythm in the rat

1993 ◽  
Vol 265 (2) ◽  
pp. R467-R473 ◽  
Author(s):  
T. Cambras ◽  
J. Vilaplana ◽  
A. Diez-Noguera
Keyword(s):  
Motor Activity ◽  
Activity Rhythm ◽  
Red Light ◽  
Bright Light ◽  
Masking Effect ◽  
Restricted Feeding ◽  
Food Component ◽  
Free Running ◽  
Access To Food

The motor activity circadian rhythm of the rat is driven by at least two different pacemakers, one entrained by light-dark cycles and the other by periodic food access. The interaction between these two pacemakers generates the overt rhythm in many variables in the rat. In this paper we study the effects of restricted feeding (RF) for > 300 days on the motor activity of two groups of eight rats each (4 males and 4 females) that were kept under different light patterns. The first group was kept under dim red light, and the second group was kept initially for 70 days under bright light and afterward under dim red light. Rats had access to food for only 2 h/day. Results show that strong alterations in the motor activity pattern, such as relative coordination, bouncing, and several cases of entrainment, are shown in the first group. When these animals return to ad libitum feeding conditions the presence of the food component is clear, in some cases for > 20 days. In contrast, the rats that were previously subjected to bright light did not entrain to RF. In this group, there was a masking effect when lights were on, but a free-running component appeared when lights were off. The endogenous period (tau) of this component was not modified during the course of the experiment. After RF these rats showed a longer tau than the former group.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of temperature and concomitant change in pH on muscle

1990 ◽  
Vol 259 (2) ◽  
pp. R204-R209 ◽  
Author(s):  
E. D. Stevens ◽  
R. E. Godt
Keyword(s):  
Ambient Temperature ◽  
Calcium Sensitivity ◽  
Skinned Fibers ◽  
Concomitant Increase ◽  
Concomitant Change ◽  
Effects Of Temperature ◽  
Contractile Performance

Contractile performance decreases with a decrease in temperature and increases with an increase in pH. In general, a decrease in ambient temperature is associated with an increase of the pH of the intracellular and extracellular fluids of ectotherms. Thus the concomitant increase in pH will to some extent counteract the effect of the decrease in temperature. We review the magnitude of this effect and show that it is modest for force (24%) but is small or negligible for speed or for variables involving time. Experiments with skinned fibers yield similar results to those with intact fibers. We argue that one important effect of the concomitant increase in pH is that it causes an increase in calcium sensitivity and that there may be a considerable metabolic saving associated with releasing less calcium at lower temperatures.

Gonadal hormones organize and modulate the circadian system of the rat

1981 ◽  
Vol 241 (1) ◽  
pp. R62-R66 ◽  
Author(s):  
H. E. Albers
Keyword(s):  
Testosterone Propionate ◽  
Wheel Running ◽  
Activity Rhythm ◽  
Gonadal Hormones ◽  
Circadian System ◽  
Female Rats ◽  
Constant Darkness ◽  
Before And After ◽  
Free Running ◽  
Free Running Period

The circadian wheel-running rhythms of gonadectomized adult male, female, and perinatally androgenized female rats, maintained in constant darkness, were examined before and after implantation of Silastic capsules containing cholesterol (C) or estradiol-17 beta (E). The free-running period of the activity rhythm (tau) before capsule implantation tended to be shorter in animals exposed to perinatal androgen. Administration of C did not reliably alter tau in any group. E significantly shortened tau in 100% of females injected with oil on day 3 of life. In females, injected with 3.5 micrograms testosterone propionate on day 3, and males, E shortened or lengthened tau, with the direction and magnitude of this change in tau inversely related to the length of the individual's pretreatment tau. These data indicate that the presence of perinatal androgen does not eliminate the sensitivity of the circadian system of the rat to estrogen, since estrogen alters tau in a manner that depends on its pretreatment length.

Restricted food access and light-dark: impact of conflicting zeitgebers on circadian rhythms of the rabbit

1993 ◽  
Vol 264 (4) ◽  
pp. R708-R715 ◽  
Author(s):  
B. Jilge ◽  
H. Stahle
Keyword(s):  
Circadian Rhythms ◽  
Phase Difference ◽  
Food Access ◽  
Activity Rhythm ◽  
Light Period ◽  
The Other ◽  
Behavioral Rhythms ◽  
Activity Component ◽  
Common Control ◽  
Free Running

Free-running circadian rhythms of rabbits were exposed to a 11:55-11:55-h light-dark (LD) schedule. After complete entrainment (63 +/- 22 days), the predominantly nocturnally active rabbits were exposed to an additional zeitgeber, restricted food access (RF), which was imposed during the light period. In five animals RF had the same period (T) as the LD cycle (23:50 h), and in five other animals TRF was 24:10 h. At a period of 23:50 h for both zeitgebers, the rhythms of four animals were stably entrained to RF, while in one animal a component of the rhythm broke away from RF and entrained to the LD zeitgeber. In animals exposed to zeitgebers of different periods most of the activity rhythm also entrained to RF, but 20 +/- 7% of the activity entrained to the LD zeitgeber. The light-entrained activity component merged with the RF component when the zeitgebers crossed, and decomposition occurred when the phase difference exceeded 4-6 h. The results indicate that two circadian oscillator systems exist in the rabbit, one entrained by light-dark cycles and the other by feeding-fasting cycles. Both exert common control over a number of overt behavioral rhythms.

If You’re Happy and You Know it Stay Alert: The Effects of Lighting on Vigilance Performance and Affective State

2021 ◽  
Vol 65 (1) ◽  
pp. 854-858
Author(s):  
Lauren E. Monroe ◽  
Samantha L. Smith
Keyword(s):  
Affective State ◽  
Light Condition ◽  
Bright Light ◽  
Extended Period ◽  
Light Therapy ◽  
Speed Of Information Processing ◽  
Attention Tasks ◽  
High Workload ◽  
Dim Light ◽  
Over Time

Vigilance, or sustained attention tasks involve detecting critical signals, embedded amid more frequent neutral signals, over an extended period of time. A decline in performance, engagement, and arousal over time, as well as high workload and stress, are common outcomes of such tasks. Exposure to broad-spectrum or short wavelength bright light has been found to positively impact alertness, speed of information processing, and mood, but has not been extensively explored in the vigilance domain. The present study explored whether a light therapy lamp could mitigate the negative vigilance outcomes found in both performance and affective state. Results indicated that the therapy light did not prevent a decline in detection of critical signals over time, nor significantly impact workload, sleepiness, or subjective stress state compared to a dim light condition. However, mood questionnaire results suggest that lighting may impact separate constructs of arousal and tiredness, warranting further research.

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