Circadian rhythms in blinded rats: correlation between pineal and activity cycles

1978 ◽  
Vol 234 (3) ◽  
pp. R110-R114
Author(s):  
C. R. Pohl ◽  
F. P. Gibbs
Keyword(s):  
Pineal Gland ◽  
Activity Rhythm ◽  
Diurnal Rhythms ◽  
Light Cycle ◽  
Activity Phase ◽  
Running Activity ◽  
Free Running ◽  
Activity Cycles ◽  
Rat Pineal Gland ◽  
Sampling Times

The rat pineal gland exhibits diurnal rhythms in levels of N-acetyltransferase activity and its substrate serotonin. We attempted to demonstrate the endogenous nature of these changes by measuring the pineal enzyme and its substrate in rats blinded for 37 and 60 days. In order to determine the proper sampling times for these one-time, terminal measurements, the running activity rhythm of each rat was monitored continuously and the animals were killed at either midrest or midrun. Circadian changes of pineal N-acetyltransferase and serotonin were demonstrated, with enzyme levels high and substrate content low during midrun. Absolute values during each activity phase were similar to those of control rats entrained to a light cycle (LD 12:12). Levels of the pineal constituents were unrelated to local time. These results suggest that rats blinded for up to 60 days maintain their free-running pineal rhythms with undamped amplitudes and in synchronization with the activity rhythm.

Disrupted circadian rhythms in VIP- and PHI-deficient mice

2003 ◽  
Vol 285 (5) ◽  
pp. R939-R949 ◽  
Author(s):  
Christopher S. Colwell ◽  
Stephan Michel ◽  
Jason Itri ◽  
Williams Rodriguez ◽  
J. Tam ◽  
...  
Keyword(s):  
Circadian Rhythms ◽  
Wheel Running ◽  
Activity Rhythm ◽  
Activity Patterns ◽  
Circadian System ◽  
Diurnal Rhythms ◽  
Constant Darkness ◽  
Light Cycle ◽  
Wild Type ◽  
Deficient Mice

The related neuropeptides vasoactive intestinal peptide (VIP) and peptide histidine isoleucine (PHI) are expressed at high levels in the neurons of the suprachiasmatic nucleus (SCN), but their function in the regulation of circadian rhythms is unknown. To study the role of these peptides on the circadian system in vivo, a new mouse model was developed in which both VIP and PHI genes were disrupted by homologous recombination. In a light-dark cycle, these mice exhibited diurnal rhythms in activity which were largely indistinguishable from wild-type controls. In constant darkness, the VIP/PHI-deficient mice exhibited pronounced abnormalities in their circadian system. The activity patterns started ∼8 h earlier than predicted by the previous light cycle. In addition, lack of VIP/PHI led to a shortened free-running period and a loss of the coherence and precision of the circadian locomotor activity rhythm. In about one-quarter of VIP/PHI mice examined, the wheel-running rhythm became arrhythmic after several weeks in constant darkness. Another striking example of these deficits is seen in the split-activity patterns expressed by the mutant mice when they were exposed to a skeleton photoperiod. In addition, the VIP/PHI-deficient mice exhibited deficits in the response of their circadian system to light. Electrophysiological analysis indicates that VIP enhances inhibitory synaptic transmission within the SCN of wild-type and VIP/PHI-deficient mice. Together, the observations suggest that VIP/PHI peptides are critically involved in both the generation of circadian oscillations as well as the normal synchronization of these rhythms to light.

scholarly journals The Effects of Intraventricular Carbachol Injections on the Free-Running Activity Rhythm of the Hamster

1988 ◽  
Vol 3 (4) ◽  
pp. 333-348 ◽  
Author(s):  
Johanna H. Meijer ◽  
E. van der Zee ◽  
M. Dietz
Keyword(s):  
Activity Rhythm ◽  
Running Activity ◽  
Free Running

Diurnal rhythms of hexosemonophosphate shunt and phosphorylase in rat pineal gland

Life Sciences ◽  
1979 ◽  
Vol 25 (6) ◽  
pp. 515-520 ◽  
Author(s):  
I. Nir ◽  
N. Hirschmann ◽  
B. Stahl
Keyword(s):  
Pineal Gland ◽  
Diurnal Rhythms ◽  
Rat Pineal Gland

Alcohol and lithium have opposing effects on the period and phase of the behavioral free-running activity rhythm

Alcohol ◽  
2015 ◽  
Vol 49 (4) ◽  
pp. 367-376 ◽  
Author(s):  
Nara F. Nascimento ◽  
Karen N. Carlson ◽  
Danielle N. Amaral ◽  
Ryan W. Logan ◽  
Joseph A. Seggio
Keyword(s):  
Activity Rhythm ◽  
Running Activity ◽  
Free Running ◽  
Opposing Effects

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.

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.

scholarly journals When the sun never sets: diverse activity rhythms under continuous daylight in free-living arctic-breeding birds

2013 ◽  
Vol 280 (1764) ◽  
pp. 20131016 ◽  
Author(s):  
Silke S. Steiger ◽  
Mihai Valcu ◽  
Kamiel Spoelstra ◽  
Barbara Helm ◽  
Martin Wikelski ◽  
...  
Keyword(s):  
Daily Activity ◽  
Radio Telemetry ◽  
Bird Species ◽  
Continuous Darkness ◽  
Activity Rhythms ◽  
Running Activity ◽  
In The Wild ◽  
Free Running ◽  
Activity Cycles ◽  
Species Specific

Circadian clocks are centrally involved in the regulation of daily behavioural and physiological processes. These clocks are synchronized to the 24 h day by external cues ( Zeitgeber ), the most important of which is the light–dark cycle. In polar environments, however, the strength of the Zeitgeber is greatly reduced around the summer and winter solstices (continuous daylight or continuous darkness). How animals time their behaviour under such conditions has rarely been studied in the wild. Using a radio-telemetry-based system, we investigated daily activity rhythms under continuous daylight in Barrow, Alaska, throughout the breeding season in four bird species that differ in mating system and parental behaviour. We found substantial diversity in daily activity rhythms depending on species, sex and breeding stage. Individuals exhibited either robust, entrained 24 h activity cycles, were continuously active (arrhythmic) or showed ‘free-running’ activity cycles. In semipalmated sandpipers, a shorebird with biparental incubation, we show that the free-running rhythm is synchronized between pair mates. The diversity of diel time-keeping under continuous daylight emphasizes the plasticity of the circadian system, and the importance of the social and life-history context. Our results support the idea that circadian behaviour can be adaptively modified to enable species-specific time-keeping under polar conditions.

Daily injections of triazolam induce long-term changes in hamster circadian period

1990 ◽  
Vol 259 (3) ◽  
pp. R514-R520 ◽  
Author(s):  
O. Van Reeth ◽  
F. W. Turek
Keyword(s):  
Circadian Clock ◽  
Activity Rhythm ◽  
Phase Relationship ◽  
Term Treatment ◽  
Dark Cycle ◽  
Running Activity ◽  
Long Term Treatment ◽  
Free Running ◽  
Induced Changes

Previous experiments in hamsters indicate that daily injections of the short-acting benzodiazepine, triazolam, can entrain the free-running circadian activity rhythm to the period of the injections and that, after discontinuation of triazolam injections, the period of the free-running activity rhythm remains close to that of the previous injection schedule for 20-50 cycles. In this paper, we extend these findings and demonstrate that 1) long-term treatment with triazolam can induce aftereffects on the period of the circadian clock underlying the activity rhythm that can last for up to 100 days, 2) triazolam-induced changes in period can lead to a loss of effect of daily injections of triazolam which can be restored if the time of injection is altered, and 3) chronic treatment with triazolam also alters the period of the circadian clock in animals entrained to a light-dark cycle, and such changes in period alter the phase relationship between the circadian clock and the entraining light-dark cycle.

Correlation of plasma corticosterone levels with running activity in the blinded rat

1976 ◽  
Vol 231 (3) ◽  
pp. 817-821 ◽  
Author(s):  
FP Gibbs
Keyword(s):  
Jugular Vein ◽  
Activity Cycle ◽  
Plasma Corticosterone ◽  
Running Wheel ◽  
Blood Samples ◽  
Running Activity ◽  
Free Running ◽  
Activity Cycles

Blinded female reats were placed in running-wheel cages to monitor the phase of their activity cycle.After approximately a month of adaptation to the wheels, jugular vein blood samples were withdrawn at the beginning and end of the running phase of activity and analyzed for plasma corticosterone. By the time blood samples were obtained, the blined rats' activity cycles had desynchronized from the lighting cycle of the room in an apparently free-running fashion, and were out of phase with each other. The corticosterone levels were high at the beginning of the running phase and low at the end: begin run corticosterone was 34.5 +/- 13, end run corticosteronewas 14.2 +/- 10 (mean +/-SD in mug/100 ml of plasma; t = 7.93, df = 82, P less than 0.001). It was concluded that blinded rats do have an adrenocortical rhythm and that it is in phase with the activity cycle of each individual rat.

Sign in / Sign up

Export Citation Format

Share Document