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.

Stability of circadian timing with age in Syrian hamsters

1998 ◽  
Vol 275 (4) ◽  
pp. R960-R968 ◽  
Author(s):  
Fred C. Davis ◽  
N. Viswanathan
Keyword(s):  
Wheel Running ◽  
Activity Level ◽  
Circadian Pacemaker ◽  
Experimental Conditions ◽  
Syrian Hamsters ◽  
Running Activity ◽  
Age Related ◽  
Wheel Running Activity ◽  
Free Running ◽  
Free Running Period

The causes of age-related disruptions in the timing of human sleep and wakefulness are not known but may include changes in both the homeostatic and circadian regulation of sleep. In Syrian hamsters the free running period of the circadian activity/rest rhythm has been reported to shorten with age. Although this has been observed under a variety of experimental conditions, the changes have been small and their consistency uncertain. In the present study, the wheel running activity/rest rhythm was continuously measured in male Syrian hamsters ( Mesocricetus auratus) in dim constant light (<1 lx) from 8 wk of age until death. Fifteen hamsters survived to at least 90 wk (28%). The average free running period of these hamsters did not change with age. In 18 hamsters that died between 50 and 88 wk, free running period also did not change before death. In contrast to free running period, other measures related to activity level changed significantly with age and before death. Despite changes in the expression of the activity/rest rhythm, the free running period of the hamster circadian pacemaker remained remarkably stable with age.

Melatonin and activity rhythm responses to light pulses in mice with the Clock mutation

2003 ◽  
Vol 284 (5) ◽  
pp. R1231-R1240 ◽  
Author(s):  
David J. Kennaway ◽  
Athena Voultsios ◽  
Tamara J. Varcoe ◽  
Robert W. Moyer
Keyword(s):  
Wheel Running ◽  
Activity Rhythm ◽  
Mutant Mice ◽  
Constant Darkness ◽  
Wild Type ◽  
Continuous Darkness ◽  
Light Pulses ◽  
Essentially Normal ◽  
Running Activity ◽  
Wheel Running Activity

Melatonin and wheel-running rhythmicity and the effects of acute and chronic light pulses on these rhythms were studied in Clock Δ19 mutant mice selectively bred to synthesize melatonin. Homozygous melatonin-proficient Clock Δ19 mutant mice ( Clock Δ19/Δ19 -MEL) produced melatonin rhythmically, with peak production 2 h later than the wild-type controls (i.e., just before lights on). By contrast, the time of onset of wheel-running activity occurred within a 20-min period around lights off, irrespective of the genotype. Melatonin production in the mutants spontaneously decreased within 1 h of the expected time of lights on. On placement of the mice in continuous darkness, the melatonin rhythm persisted, and the peak occurred 2 h later in each cycle over the first two cycles, consistent with the endogenous period of the mutant. This contrasted with the onset of wheel-running activity, which did not shift for several days in constant darkness. A light pulse around the time of expected lights on followed by constant darkness reduced the expected 2-h delay of the melatonin peak of the mutants to ∼1 h and advanced the time of the melatonin peak in the wild-type mice. When the Clock Δ19/Δ19 -MEL mice were maintained in a skeleton photoperiod of daily 15-min light pulses, a higher proportion entrained to the schedule (57%) than melatonin-deficient mutants (9%). These results provide compelling evidence that mice with the Clock Δ19 mutation express essentially normal rhythmicity, albeit with an underlying endogenous period of 26–27 h, and they can be entrained by brief exposure to light. They also raise important questions about the role of Clock in rhythmicity and the usefulness of monitoring behavioral rhythms compared with hormonal rhythms.

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.

Activity rhythm of golden hamster (Mesocricetus auratus) can be entrained to a 19-h light-dark cycle

2005 ◽  
Vol 289 (4) ◽  
pp. R998-R1005 ◽  
Author(s):  
Juan J. Chiesa ◽  
Montserrat Anglès-Pujolràs ◽  
Antoni Díez-Noguera ◽  
Trinitat Cambras
Keyword(s):  
Golden Hamster ◽  
Wheel Running ◽  
Activity Rhythm ◽  
Mesocricetus Auratus ◽  
Precise Determination ◽  
Dark Cycle ◽  
Running Wheel ◽  
Running Activity ◽  
Wheel Running Activity

Both temporary access to a running wheel and temporary exposure to light systematically influence the phase producing entrainment of the circadian activity rhythm in the golden hamster ( Mesocricetus auratus). However, precise determination of entrainment limits remains methodologically difficult, because such calculations may be influenced by varying experimental paradigms. In this study, effects on the entrainment of the activity pattern during successive light-dark (LD) cycles of stepwise decreasing periods, as well as wheel running activity, were investigated. In particular, the hamster activity rhythm under LD cycles with a period (T) shorter than 22 h was studied, i.e., when the LD cycle itself had been shown to be an insufficiently strong zeitgeber to synchronize activity rhythms. Indeed, it was confirmed that animals without a wheel do not entrain under 11:11-h LD cycles (T = 22 h). Subsequently providing hamsters continuous access to a running wheel established entrainment to T = 22 h. Moreover, this paradigm underwent further reductions of the T period to T = 19.6 h without loss of entrainment. Furthermore, restricting access to the wheel did not result in loss of entrainment, while even entrainment to T = 19 h was observed. To explain this observed shift in the lower entrainment limit, our speculation centers on changes in pacemaker response facilitated by stepwise changes of T spaced very far apart, thus allowing time for adaptation.

Circadian rhythms of sleep and wakefulness in mice: analysis using long-term automated recording of sleep

1985 ◽  
Vol 248 (3) ◽  
pp. R320-R330 ◽  
Author(s):  
G. S. Richardson ◽  
M. C. Moore-Ede ◽  
C. A. Czeisler ◽  
W. C. Dement
Keyword(s):  
Circadian Rhythms ◽  
Rem Sleep ◽  
Wheel Running ◽  
Nrem Sleep ◽  
Sleep State ◽  
Continuous Darkness ◽  
Running Activity ◽  
Wheel Running Activity ◽  
Significant Difference ◽  
Wake State

Circadian rhythms of wheel-running activity and polygraphically defined wakefulness, rapid-eye-movement (REM) sleep and non-REM (NREM) sleep were continuously observed in ten mice (Mus musculus) under both alternating light-dark (LD 12:12) and continuous darkness (DD) conditions. Sleep-wake state was determined automatically using a computer-based method that allowed continuous recordings of from 60 to 280 days in duration. The sleep-wake state percentages (of the circadian cycle) thus obtained were in substantial agreement with other estimates for this or similar strains and showed no significant difference between LD 12:12 (wake 54.3%, NREM sleep 38.1%, REM sleep 7.6%) and DD (wake 53.1%, NREM sleep 39.9%, REM sleep 7.0%) conditions. All 10 mice exhibited clear circadian rhythms in each of the three states and wheel-running activity under both lighting conditions for the entire duration of observation. Probability functions, computed using stationary sections of data from all 10 mice, showed distinct waveforms for all three states and wheel running. These waveforms were remarkably similar under entrained and free-running conditions. This documentation of sustained circadian rhythmicity in sleep-wake state throughout observations of unprecedented length contradicts the currently common assertion that circadian control of sleep state is weaker than that of activity.

scholarly journals SCN lesions abolish ultradian and circadian components of activity rhythms in LEW/Ztm rats

1989 ◽  
Vol 256 (5) ◽  
pp. R1027-R1039 ◽  
Author(s):  
F. Wollnik ◽  
F. W. Turek
Keyword(s):  
Activity Pattern ◽  
Wheel Running ◽  
Dark Cycle ◽  
Spectral Estimates ◽  
Running Activity ◽  
Wheel Running Activity ◽  
Neural Substrate ◽  
Free Running ◽  
Males And Females ◽  
Periodogram Analysis

A trimodal locomotor activity pattern has been observed in LEW/Ztm rats. Complete and partial lesions of the suprachiasmatic nucleus (SCN) were used to determine whether the same neural substrate may underlie the circadian rhythms and the ultradian modulation of wheel-running activity in these rats. Whereas sham lesions had little or no effect on the wheel-running activity pattern, complete SCN lesions resulted in a complete loss of circadian and ultradian activity components under free-running or 12:12 h light-dark cycle (12:12 LD) conditions. Ultradian and circadian activity components were still present after partial SCN lesions. Periodogram analysis for any given animal revealed that the ultradian periods were always submultiples of the entrained or free-running circadian period. Furthermore there was a high correlation between the amplitudes of circadian and ultradian spectral estimates, but with a different slope in males and females. These results indicate that in LEW/Ztm rats the SCN contributes to the control of both the circadian wheel-running rhythm and the trimodal ultradian modulation of that behavior.

scholarly journals Age-related changes in circadian responses to dark pulses

2000 ◽  
Vol 279 (2) ◽  
pp. R586-R590 ◽  
Author(s):  
Marilyn J. Duncan ◽  
Anthony W. Deveraux
Keyword(s):  
Wheel Running ◽  
Activity Rhythm ◽  
Circadian Pacemaker ◽  
Running Activity ◽  
Age Related ◽  
Wheel Running Activity ◽  
Significant Difference ◽  
Time Signals ◽  
Dark Pulse ◽  
Age Related Changes

Aging involves many alterations in circadian rhythms, including a loss of sensitivity to both photic and nonphotic time signals. This study investigated the sensitivity of young and old hamsters to the phase advancing effect of a 6-h dark pulse on the locomotor activity rhythm. Each hamster was tested four times during a period of ∼9 mo; periods of exposure to a 14-h photoperiod were alternated with the periods of exposure to constant light (20–80 lx), during which the dark pulses were administered. There was no significant difference in the phase shifts exhibited by the young (4–10 mo) and old hamsters (19–25 mo) or in the amount of wheel running activity displayed during each dark pulse. However, young hamsters had a significantly greater propensity to exhibit split rhythms immediately after the dark pulses. These results suggest that, although aging does not reduce the sensitivity of the circadian pacemaker to this nonphotic signal, it alters one property of the pacemaker, i.e., the flexibility of the coupling of its component oscillators.

scholarly journals Altered circadian activity and sleep/wake rhythms in the stable tubule only polypeptide (STOP) null mouse model of schizophrenia

SLEEP ◽  
2020 ◽  
Author(s):  
Samuel Deurveilher ◽  
Kristin Robin Ko ◽  
Brock St C Saumure ◽  
George S Robertson ◽  
Benjamin Rusak ◽  
...  
Keyword(s):  
Wheel Running ◽  
Active Phase ◽  
Null Mouse ◽  
Wild Type ◽  
Activity Rhythms ◽  
Lighting Conditions ◽  
Running Activity ◽  
Wheel Running Activity ◽  
Lower Amplitude ◽  
Free Running

Abstract Sleep and circadian rhythm disruptions commonly occur in individuals with schizophrenia. Stable tubule only polypeptide (STOP) knockout (KO) mice show behavioral impairments resembling symptoms of schizophrenia. We previously reported that STOP KO mice slept less and had more fragmented sleep and waking than wild-type littermates under a light/dark (LD) cycle. Here, we assessed the circadian phenotype of male STOP KO mice by examining wheel-running activity rhythms and EEG/EMG-defined sleep/wake states under both LD and constant darkness (DD) conditions. Wheel-running activity rhythms in KO and wild-type mice were similarly entrained in LD, and had similar free-running periods in DD. The phase delay shift in response to a light pulse given early in the active phase under DD was preserved in KO mice. KO mice had markedly lower activity levels, lower amplitude activity rhythms, less stable activity onsets, and more fragmented activity than wild-type mice in both lighting conditions. KO mice also spent more time awake and less time in rapid eye movement sleep (REMS) and non-REMS (NREMS) in both LD and DD conditions, with the decrease in NREMS concentrated in the active phase. KO mice also showed altered EEG features and higher amplitude rhythms in wake and NREMS (but not REMS) amounts in both lighting conditions, with a longer free-running period in DD, compared to wild-type mice. These results indicate that the STOP null mutation in mice altered the regulation of sleep/wake physiology and activity rhythm expression, but did not grossly disrupt circadian mechanisms.

Aging and photoperiod affect entrainment and quantitative aspects of locomotor behavior in Syrian hamsters

1997 ◽  
Vol 272 (4) ◽  
pp. R1219-R1225 ◽  
Author(s):  
K. Scarbrough ◽  
S. Losee-Olson ◽  
E. P. Wallen ◽  
F. W. Turek
Keyword(s):  
Locomotor Activity ◽  
Wheel Running ◽  
Activity Rhythm ◽  
Age Groups ◽  
Temporal Distribution ◽  
Similar Rate ◽  
Middle Aged ◽  
Running Activity ◽  
Age Related ◽  
Wheel Running Activity

Aging affects the regulation of diurnal and circadian rhythmicity. We tested the hypothesis that the age-related difference in the phase angle of entrainment of the locomotor activity rhythm to a light-dark (LD) cycle would be greater under LD 6:18 than LD 14:10. We also analyzed changes in quantitative aspects of wheel-running behavior according to age group. Young (9-wk-old), middle-aged (11- to 12-mo-old), and old (15- to 17-mo-old) male golden hamsters were entrained to a 14:10 LD cycle followed by re-entrainment to a 6:18 LD cycle. Fourteen days after the start of locomotor recording in LD 14:10 and again after 27 days in LD 6:18, the phase of activity onset, the total number of wheel revolutions performed per day, the peak intensity of wheel-running activity, the duration of the active period, and the level of fragmentation of locomotor activity were quantitated. We also studied the temporal distribution of the largest bout of wheel-running activity among the age groups in both photoperiods. Short days induced testicular regression at a similar rate among young, middle-aged, and old hamsters. The data are discussed in terms of the effects of age on overall circadian organization in the seasonally changing environment.

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