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.

Sex differences in the circadian control of hamster wheel-running activity

1983 ◽  
Vol 244 (1) ◽  
pp. R93-R105 ◽  
Author(s):  
F. C. Davis ◽  
J. M. Darrow ◽  
M. Menaker
Keyword(s):  
Sex Differences ◽  
Sex Difference ◽  
Wheel Running ◽  
Phase Shifts ◽  
Light Cycle ◽  
Dark Cycle ◽  
Running Activity ◽  
Wheel Running Activity ◽  
Activity Onset ◽  
Males And Females

The circadian pacemaker that underlies the wheel-running activity of hamsters was studied in males and females. Sex differences were found in the mechanism by which the pacemaker entrains to light-dark cycles and in the timing of activity onset. When exposed to a light-dark cycle with a period of 24.75 h (with 1 h of light/cycle), males show a greater ability to maintain entrainment than do females. This difference in the upper limit of entrainment appears due to a sex difference in the magnitude of light-induced phase shifts. A small difference in free-running period may also contribute to the sex difference in entrainment. Two weeks after castration of adults, the sex difference in entrainment is not affected, indicating that the difference does not depend on circulating gonadal steroids or on estrous cyclicity of the female. However, castration of females at an early age increases their ability to entrain, whereas long-term castration of males seems to reduce entrainment ability. During entrainment to a 24-h light-dark cycle (LD 14:10), females were found to begin their daily activity before males and before castrated females. This difference is consistent with a sex difference in the magnitude of light-induced phase shifts and in entrainment of the pacemaker. However, evidence is given that the sex difference in activity onset might also be caused by a sex difference in the relationship of locomotor activity to the pacemaker in intact males and females.

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.

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.

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.

Restricted feeding entrains circadian wheel-running activity rhythms of the kowari

1991 ◽  
Vol 261 (4) ◽  
pp. R819-R827 ◽  
Author(s):  
G. A. Kennedy ◽  
G. J. Coleman ◽  
S. M. Armstrong
Keyword(s):  
Pilot Study ◽  
Wheel Running ◽  
Light Period ◽  
Restricted Feeding ◽  
Activity Rhythms ◽  
Running Activity ◽  
Wheel Running Activity ◽  
Free Running ◽  
Anticipatory Activity ◽  
Constant Dark

The effect of daily restricted feeding (RF) on the circadian wheel-running rhythms of the kowari, Dasyuroides byrnei, was examined in two experiments. Kowaris were presented with a preferred food (determined in a pilot study) during a daily 2-h meal in the light period of a 14:10 light-dark (LD) cycle (expts 1 and 2), during constant dark (DD) immediately after termination of the LD cycle (expt 1), and during DD when kowaris were free running (expt 1). Results showed that 1) RF elicited anticipatory activity similar in duration and phasing to that observed in the rat; 2) cycles of meal-associated activity free ran for up to 6 days after the termination of RF; 3) activity persists at a phase near that of the former mealtime during periods of food deprivation; and 4) activity indicative of beating between two pacemakers occurred when feeding was restricted to the L period of LD cycles. Together these observations suggest that the activity rhythms of the kowari may be controlled by separate, but possibly coupled, light-entrainable and food-entrainable pacemakers, as are those of the rat.

scholarly journals The Phosphorylation of CREB at Serine 133 Is a Key Event for Circadian Clock Timing and Entrainment in the Suprachiasmatic Nucleus

2018 ◽  
Vol 33 (5) ◽  
pp. 497-514 ◽  
Author(s):  
Kelin L. Wheaton ◽  
Katelin F. Hansen ◽  
Sydney Aten ◽  
Kyle A. Sullivan ◽  
Hyojung Yoon ◽  
...  
Keyword(s):  
Circadian Clock ◽  
Suprachiasmatic Nucleus ◽  
Wheel Running ◽  
Slice Culture ◽  
Creb Phosphorylation ◽  
Running Activity ◽  
Wheel Running Activity ◽  
Free Running

Within the suprachiasmatic nucleus (SCN)—the locus of the master circadian clock— transcriptional regulation via the CREB/CRE pathway is implicated in the functioning of the molecular clock timing process, and is a key conduit through which photic input entrains the oscillator. One event driving CRE-mediated transcription is the phosphorylation of CREB at serine 133 (Ser133). Indeed, numerous reporter gene assays have shown that an alanine point mutation in Ser133 reduces CREB-mediated transcription. Here, we sought to examine the contribution of Ser133 phosphorylation to the functional role of CREB in SCN clock physiology in vivo. To this end, we used a CREB knock-in mouse strain, in which Ser133 was mutated to alanine (S/A CREB). Under a standard 12 h light-dark cycle, S/A CREB mice exhibited a marked alteration in clock-regulated wheel running activity. Relative to WT mice, S/A CREB mice had highly fragmented bouts of locomotor activity during the night phase, elevated daytime activity, and a delayed phase angle of entrainment. Further, under free-running conditions, S/A CREB mice had a significantly longer tau than WT mice and reduced activity amplitude. In S/A CREB mice, light-evoked clock entrainment, using both Aschoff type 1 and 6 h “jet lag” paradigms, was markedly reduced relative to WT mice. S/A CREB mice exhibited attenuated transcriptional drive, as assessed by examining both clock-gated and light-evoked gene expression. Finally, SCN slice culture imaging detected a marked disruption in cellular clock phase synchrony following a phase-resetting stimulus in S/A CREB mice. Together, these data indicate that signaling through CREB phosphorylation at Ser133 is critical for the functional fidelity of both SCN timing and entrainment.

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