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.

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.

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.

Selective deficits in the circadian light response in mice lacking PACAP

2004 ◽  
Vol 287 (5) ◽  
pp. R1194-R1201 ◽  
Author(s):  
C. S. Colwell ◽  
S. Michel ◽  
J. Itri ◽  
W. Rodriguez ◽  
J. Tam ◽  
...  
Keyword(s):  
Wheel Running ◽  
Light Exposure ◽  
Light Response ◽  
Phase Shifts ◽  
Circadian System ◽  
Loss Of Function ◽  
Running Activity ◽  
Wheel Running Activity ◽  
Deficient Mice

Previous studies indicate that light information reaches the suprachiasmatic nucleus through a subpopulation of retinal ganglion cells that contain both glutamate and pituitary adenylyl cyclase-activating peptide (PACAP). Although the role of glutamate in this pathway has been well studied, the involvement of PACAP and its receptors is only beginning to be understood. To investigate the functions of PACAP in vivo, we developed a mouse model in which the gene coding for PACAP was disrupted by targeted homologous recombination. RIA was used to confirm a lack of detectable PACAP protein in these mice. PACAP-deficient mice exhibited significant impairment in the magnitude of the response to brief light exposures with both light-induced phase delays and advances of the circadian system impacted. This mutation equally impacted phase shifts induced by bright and dim light exposure. Despite these effects on phase shifting, the loss of PACAP had only limited effects on the generation of circadian oscillations, as measured by rhythms in wheel-running activity. Unlike melanopsin-deficient mice, the mice lacking PACAP exhibited no loss of function in the direct light-induced inhibition of locomotor activity, i.e., masking. Finally, the PACAP-deficient mice exhibited normal phase shifts in response to exposure to discrete dark treatments. The results reported here show that the loss of PACAP produced selective deficits in the light response of the circadian system.

Odor-specific effects on reentrainment following phase advances in the diurnal rodent, Octodon degus

2006 ◽  
Vol 291 (6) ◽  
pp. R1808-R1816 ◽  
Author(s):  
Tammy J. Jechura ◽  
Megan M. Mahoney ◽  
Cheryl D. Stimpson ◽  
Theresa M. Lee
Keyword(s):  
Wheel Running ◽  
Hormone Replacement ◽  
Complete Recovery ◽  
Phase Shifts ◽  
Phase Shifting ◽  
Phase Advance ◽  
Single Male ◽  
Octodon Degus ◽  
Running Activity ◽  
Wheel Running Activity

Reentrainment following phase shifts of the light-dark (LD) cycle is accelerated in Octodon degus in the presence of olfactory social cues (i.e., odors) produced by conspecifics. However, not all odors from conspecifics were effective in facilitating reentrainment after a phase advance. In the current experiments, we examined whether nonanimal odors, odors from another species, or conspecific odors, including those manipulated by steroid hormones, can cause the same increased reentrainment of wheel-running activity as odors from an intact, adult female degu. A variety of odors, each selected to probe a particular aspect of the reentrainment acceleration phenomenon, were presented to a group of phase-shifting female degus. The shifting females (test animals) responded to odors of intact, female degu donors with decreased reentrainment time, but odors of ovariectomized (OVX), OVX with a single hormone replacement capsule (estradiol or progesterone) or phase-shifting females had no effect. Multiple males were effective odor donors, whereas a single male was ineffective in earlier studies. Rats and cloves were not effective in accelerating reentrainment. Furthermore, odors from rats delayed reentrainment. We conclude that the odors that effectively accelerate degu reentrainment after a phase advance of the LD cycle are species specific. We also report that repeated phase shifts, followed by complete recovery of phase relationships, do not alter the rate of recovery from a phase shift over time. These data suggest that in O. degus, a social species, odors may reinforce and strengthen the salience of the photic zeitgeber and/or facilitate synchronization of rhythms between animals.

Effects of aging on the circadian rhythm of wheel-running activity in C57BL/6 mice

1997 ◽  
Vol 273 (6) ◽  
pp. R1957-R1964 ◽  
Author(s):  
Verónica S. Valentinuzzi ◽  
Kathryn Scarbrough ◽  
Joseph S. Takahashi ◽  
Fred W. Turek
Keyword(s):  
Wheel Running ◽  
Activity Rhythm ◽  
Laboratory Mouse ◽  
Active Phase ◽  
Constant Darkness ◽  
Age Difference ◽  
Running Activity ◽  
Wheel Running Activity ◽  
Activity Onset ◽  
Old Mice

The effects of age on the circadian clock system have been extensively studied, mainly in two rodent species, the laboratory rat and the golden hamster. However, less information is available on how aging alters circadian rhythmicity in a commonly studied rodent animal model, the mouse. Therefore, in the present study we compared the rhythm of wheel-running activity in adult (6–9 mo) and old (19–22 mo) C57BL/6J mice maintained under different lighting conditions for a period of 4 mo. During this period, mice were subjected to phase advances and phase delays of the light-dark (LD) cycle and eventually to constant darkness (DD). In LD (12 h light, 12 h dark), old mice exhibited delayed activity onset relative to light offset and an increase in the variability of activity onset compared with adult mice. After a 4-h phase advance of the LD cycle, old mice took significantly longer to reentrain their activity rhythm when compared with adult animals. Old mice also demonstrated a decline in the number of wheel revolutions per day and a tendency toward a decrease in the length of the active phase. An increase in fragmentation of activity across the 24-h day was obvious in aging animals, with bouts of activity being shorter and longer rest periods intervening between them. No age difference was detected in the maximum intensity of wheel-running activity. In DD, the free-running period was significantly longer in old mice compared with adults. In view of the rapidly expanding importance of the laboratory mouse for molecular and genetic studies of the mammalian nervous system, the present results provide a basis at the phenotypic level to begin to apply genetic methods to the analysis of circadian rhythms and aging in mammals.

Abstract 302: Sex Differences In Nonlinear Dynamics And Their Circadian Variation In Control Dogs And In A New Arrhythmogenic Canine Model Of Heart Failure

2014 ◽  
Vol 115 (suppl_1) ◽  
Author(s):  
Yujie Zhu ◽  
Steven M Pogwizd
Keyword(s):  
Nonlinear Dynamics ◽  
Heart Failure ◽  
Sex Differences ◽  
Sex Difference ◽  
Circadian Variation ◽  
Holter Monitoring ◽  
Canine Model ◽  
Nonlinear Parameters ◽  
Arrhythmogenic Substrate ◽  
Males And Females

Introduction: Females can be more arrhythmogenic than males, and this sex difference can persist with development of chronic heart failure (CHF). The aim of this study was to investigate sex differences in the arrhythmogenic substrate in control dogs and in a new arrhythmogenic canine model of CHF. Methods: CHF was induced in 30 dogs by aortic insufficiency and aortic constriction. Holter monitoring assessed VT and PVCs from 30 dogs, as well as traditional HRV measures and nonlinear dynamics (including correlation dimension (CD), detrended fluctuations analysis α1 (DFAα1), and Shannon entropy (SE)) at baseline, 240 days (240d) and 720 days (720d) after CHF induction. Results: At baseline, females had lower LF/HF (0.27±0.03 vs 0.33±0.02, p=0.04), CD (1.60±0.17 vs 2.21±0.15, p=0.01), DFAα1 (0.62±0.03 vs 0.72±0.03, p=0.03), and SE (2.99±0.02 vs 3.10±0.03, p=0.03 vs males). Females lacked circadian variation in LF/HF, DFAα1, and SE while males had circadian variation in all of these. Of 11 dogs with frequent runs of VT and PVCs, 95% and 91% of total VT runs and total PVCs, respectively, were in females. With CHF, all these linear and nonlinear parameters progressively declined in males and females. CHF females had less decline in LF/HF than males so that by 720 days there was no more sex difference (0.24±0.06, 0.17±0.03 in females vs 0.22±0.05, 0.18±0.01 in males at 240d, 720d). However, for nonlinear parameters of CD, DFAα1, and SE, CHF females had lower values than males (CD: 1.56±0.21, 0.99±0.32 vs 1.87±0.24, 1.50±0.34; DFAα1: 0.51±0.05, 0.43±0.04 vs 0.54±0.07, 0.48±0.04; and SE 2.93±0.08, 2.76±0.08 vs 3.01±0.11, 2.91±0.04 in females vs males at 240d, 720d). With CHF, circadian variation in CD, DFAα1, and SE were lost in both males and females. Conclusions: There are sex differences in the arrhythmogenic substrate in control dogs and in this new arrhythmogenic canine model of moderate CHF. At baseline, females have lower sympathetic stimulation, reduced cardiac chaos, and loss of circadian variation in nonlinear dynamics. With CHF, sex differences in nonlinear dynamics persist; this reflects a loss of complexity and fractal properties that could contribute to increased arrhythmias in female CHF dogs.

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