Dark pulses affect the circadian rhythm of activity in hamsters kept in constant light

1982 ◽  
Vol 242 (1) ◽  
pp. R44-R50 ◽  
Author(s):  
G. B. Ellis ◽  
R. E. McKlveen ◽  
F. W. Turek
Keyword(s):  
Response Curve ◽  
Phase Response Curve ◽  
Circadian System ◽  
Constant Light ◽  
Constant Darkness ◽  
Light Pulses ◽  
Subjective Night ◽  
Free Running ◽  
Male Golden Hamsters ◽  
Formal Properties

We compared the effects of light pulses in constant darkness (DD) and dark pulses in constant light (LL) on the free-running rhythm of locomotor activity in male golden hamsters. Light pulses yielded advances, delays, or no change in the rhythm of activity. These data conform to a typical phase-response curve; this curve was unaffected by pinealectomy. Dark pulses occurring either late in the subjective night or early in the subjective day had little effect. In contrast, dark pulses occurring either late in the subjective day or early in the subjective night altered the rhythm in one of three ways: advance of the rhythm; splitting into two components; or induction of a new component, in phase with the pulse. Because dark pulses in LL perturb the circadian system in a different manner than do light pulses in DD, they may have value in identifying heretofore unknown aspects of circadian systems. As such, the use of dark pulses to perturb circadian rhythmicity will be a useful tool in examining the formal properties of circadian systems.

Extraretinal photoreception in the lizard Sceloporus occidentalis: phase response curve

1985 ◽  
Vol 248 (4) ◽  
pp. R407-R414
Author(s):  
H. Underwood
Keyword(s):  
Phase Response Curve ◽  
Circadian System ◽  
Phase Response ◽  
Fluorescent Light ◽  
Response Curves ◽  
Sceloporus Occidentalis ◽  
Light Pulses ◽  
Threefold Increase ◽  
Free Running ◽  
Free Running Period

All submammalian vertebrates have extraretinal photoreceptors (ERR) that can mediate entrainment of circadian rhythms to 24-h light-dark (LD) cycles. Phase response curves (PRC) for 6-h fluorescent light pulses were generated for lizards (Sceloporus occidentalis) previously subjected to sectioning of both optic nerves (ONX). The PRC for ONX lizards (only ERRs present) shows a threefold increase in the amplitude of both the advance and delay portions of the PRC compared with a PRC previously generated for sighted S. occidentalis. Also, in contrast to sighted lizards the area of the advance part of the PRC of ONX lizards is greater than the delay portion. Consistent with the shape of the respective PRCs in ONX vs. sighted lizards are the following facts. 1) The range of entrainment to LD cycles is greater in ONX lizards; some sighted lizards free-ran when exposed to LD 6:21.5 or LD 6:23.5 but entrained after ONX lizards reentrained to an 8-h shift in the phase of a LD 6:18 cycle significantly faster than sighted lizards. 3) Forty-two percent of ONX lizards showed a shorter free-running period (tau) in LL than DD, whereas 90% of sighted lizards showed a longer free-running period in LL than in DD. In those lizards in which tau LL greater than tau DD, the the average tau change in ONX lizards in was significantly less than that observed in sighted lizards. These results are consistent with the hypothesis that the eyes have an "inhibitory" role in the circadian system of S. occidentalis.

Light-induced uncoupling of multioscillatory circadian system in a diurnal rodent, Asian chipmunk

1999 ◽  
Vol 276 (5) ◽  
pp. R1390-R1396 ◽  
Author(s):  
Sato Honma ◽  
Ken-Ichi Honma
Keyword(s):  
Circadian Rhythm ◽  
Light Pulse ◽  
Response Curve ◽  
Phase Response Curve ◽  
Circadian System ◽  
Locomotor Rhythm ◽  
Subjective Night ◽  
Large Phase ◽  
Activity Band ◽  
Oscillatory Coupling

Responses of the circadian locomotor rhythm to a single light pulse were examined in a diurnal rodent, Asian chipmunk, by exposing it to a 1-h light pulse of 2,000 lx under constant conditions. A light pulse given at the beginning and end of the subjective night produced a phase delay and advance shifts, respectively. When pulsed around the midpoint of the subjective night, the circadian rhythm was shifted as much as 12 h in most animals or became arrhythmic in some. In the latter case, an additional light pulse restored the circadian rhythm. Some animals were unresponsive to light. The phase response curve is categorized as type 0. A large phase-shift was sometimes followed by splitting of an activity band into two components. These results are best explained by an assumption that the chipmunk circadian system is composed of two mutually coupled major oscillators, each of which is constituted by multiple oscillators. Our results suggest that light affects the oscillatory coupling not only of the major oscillators but also of constitutional oscillators.

scholarly journals Phenotypic and genetic analysis of Clock, a new circadian rhythm mutant in Drosophila melanogaster.

Genetics ◽  
1990 ◽  
Vol 125 (3) ◽  
pp. 557-578 ◽  
Author(s):  
M S Dushay ◽  
R J Konopka ◽  
D Orr ◽  
M L Greenacre ◽  
C P Kyriacou ◽  
...  
Keyword(s):  
Response Curve ◽  
Phase Response Curve ◽  
Activity Rhythm ◽  
Courtship Song ◽  
Activity Rhythms ◽  
Light Pulses ◽  
Essentially Normal ◽  
Running Activity ◽  
Short Period ◽  
Free Running

Abstract Clock is a semidominant X-linked mutation that results in shortening the period of Drosophila melanogaster's free-running locomotor activity rhythm from ca. 24.0 to ca. 22.5 hr. This mutation similarly shortened the phase response curve, determined by resetting activity rhythms with light pulses. Eclosion peaks for Clk cultures were separated by only 22.5 hr instead of the normal 24 hr. Clk was mapped close to, but separable from, another rhythm mutation--period01--by recombination. The estimated distance between these two mutations was short enough to suggest that Clk could be a per allele. If this is the case, the new mutant is unique in that it, unlike other per variants, is associated with essentially normal 1-min courtship song rhythms when Clk is expressed in males. Also, the new rhythm variant could not, in contrast to a short-period per mutation, have its effects on free-running activity rhythms uncovered by deletions. This result, and the lack of coverage of Clk's effects by duplications, suggest that it is not a simple hypomorphic or amorphic mutation.

Administering triazolam on a circadian basis entrains the activity rhythm of hamsters

1989 ◽  
Vol 256 (3) ◽  
pp. R639-R645
Author(s):  
O. Van Reeth ◽  
F. W. Turek
Keyword(s):  
Response Curve ◽  
Wheel Running ◽  
Phase Response Curve ◽  
Activity Rhythm ◽  
Phase Relationship ◽  
Phase Shifts ◽  
Phase Response ◽  
Light Pulses ◽  
Circadian Time ◽  
Free Running

A single injection of the short-acting benzodiazepine, triazolam, can induce permanent phase shifts in the circadian rhythm of locomotor activity in free-running hamsters, with the direction and magnitude of the phase shifts being dependent on the circadian time of treatment. The shape of the "phase-response curve" to triazolam injections is totally different from that for light pulses. These findings raise the possibility that repeated injections of triazolam on a circadian basis might be capable of entraining the circadian pacemaker underlying the activity rhythm of hamsters and that the entrainment pattern might differ from that observed in animals entrained to light pulses. To test this hypothesis, blind hamsters received intraperitoneal injections of triazolam (or vehicle) every 23.34, 23.72, 24.00 or 24.66 h for 19-20 days, and the effect of these injections on the period of the rhythm of wheel-running behavior was determined during and after treatment. Repeated injections of 0.1 mg triazolam at these time intervals resulted in the entrainment of the activity rhythm in 36 of 40 animals, whereas 0 of 40 animals entrained to vehicle injections. Importantly, the phase relationship between triazolam injections and the circadian activity rhythm was dependent on the period of drug treatment and could be predicted from the phase-response curve to single injections of triazolam. These phase relationships are dramatically different from those observed between the activity rhythm and 1-h light pulses presented at similar circadian intervals.(ABSTRACT TRUNCATED AT 250 WORDS)

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.

Organization of rat circadian rhythms during daily infusion of melatonin or S20098, a melatonin agonist

1999 ◽  
Vol 277 (3) ◽  
pp. R812-R828 ◽  
Author(s):  
B. Pitrosky ◽  
R. Kirsch ◽  
A. Malan ◽  
E. Mocaer ◽  
P. Pevet
Keyword(s):  
Body Temperature ◽  
Circadian Rhythms ◽  
Phase Response Curve ◽  
Constant Darkness ◽  
Time Interval ◽  
General Activity ◽  
Activity Peak ◽  
Free Running ◽  
Wheel Activity ◽  
Free Running Period

Daily administration of melatonin or S20098, a melatonin agonist, is known to entrain the free-running circadian rhythms of rats. The effects of the duration of administration on entrainment were studied. The animals demonstrated free-running circadian rhythms (running-wheel activity, body temperature, general activity) in constant darkness. Daily infusions of melatonin or S20098 for 1, 8, or 16 h entrained the circadian rhythms to 24 h. Two daily infusions of 1 h (separated by 8 h) entrained the activity peak within the shorter time interval. The entraining properties of melatonin and S20098 were similar and were affected neither by pinealectomy nor by infusion of 1- or 8-h duration. However, with 16-h infusion, less than half of the animals became entrained. Once entrained, the phase angle between the onset of infusion and the rhythms (onset of activity or acrophase of body temperature) increased with the duration of infusion. Before entrainment, the free-running period increased with the duration of infusion, an effect that was not predictable from the phase response curve.

scholarly journals PDF neuron firing phase-shifts key circadian activity neurons in Drosophila

eLife ◽  
2014 ◽  
Vol 3 ◽  
Author(s):  
Fang Guo ◽  
Isadora Cerullo ◽  
Xiao Chen ◽  
Michael Rosbash
Keyword(s):  
Response Curve ◽  
Phase Response Curve ◽  
Receptor Expression ◽  
Phase Shifting ◽  
Constant Darkness ◽  
Behavioral Rhythms ◽  
Circadian Phase ◽  
Phase Adjustment ◽  
Drosophila Brain ◽  
A Cell

Our experiments address two long-standing models for the function of the Drosophila brain circadian network: a dual oscillator model, which emphasizes the primacy of PDF-containing neurons, and a cell-autonomous model for circadian phase adjustment. We identify five different circadian (E) neurons that are a major source of rhythmicity and locomotor activity. Brief firing of PDF cells at different times of day generates a phase response curve (PRC), which mimics a light-mediated PRC and requires PDF receptor expression in the five E neurons. Firing also resembles light by causing TIM degradation in downstream neurons. Unlike light however, firing-mediated phase-shifting is CRY-independent and exploits the E3 ligase component CUL-3 in the early night to degrade TIM. Our results suggest that PDF neurons integrate light information and then modulate the phase of E cell oscillations and behavioral rhythms. The results also explain how fly brain rhythms persist in constant darkness and without CRY.

Light effects on circadian timing system of a diurnal primate, the squirrel monkey

1985 ◽  
Vol 249 (2) ◽  
pp. R274-R280 ◽  
Author(s):  
T. M. Hoban ◽  
F. M. Sulzman
Keyword(s):  
Squirrel Monkey ◽  
Response Curve ◽  
Phase Response Curve ◽  
Phase Response ◽  
Day Length ◽  
Circadian Timing ◽  
Subjective Night ◽  
Timing System ◽  
Circadian Timing System ◽  
Light Effects

We examined light effects on the circadian timing system of the squirrel monkey. A phase-response curve to 1-h pulses of light was constructed for the drinking rhythm of six animals. The phase-response curve was the same type as that exhibited by nocturnal rodents, with phase delays occurring early in the subjective night and phase advances late in the subjective night. The range of entrainment of 10 monkeys to days with 1 h light and x h dark was determined. Five monkeys used to generate the phase-response curve were also used in the range of entrainment determination. For short light-dark cycles the range of entrainment was smaller than that expected, with no monkey entraining to a day length of less than 23.5 h.

scholarly journals A Phase Response Curve to Single Bright Light Pulses in Human Subjects

2003 ◽  
Vol 549 (3) ◽  
pp. 945-952 ◽  
Author(s):  
Sat Bir S. Khalsa ◽  
Megan E. Jewett ◽  
Christian Cajochen ◽  
Charles A. Czeisler
Keyword(s):  
Response Curve ◽  
Phase Response Curve ◽  
Human Subjects ◽  
Bright Light ◽  
Phase Response ◽  
Light Pulses
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