scholarly journals Resetting of the hamster circadian system by dark pulses

2006 ◽  
Vol 290 (3) ◽  
pp. R785-R792 ◽  
Author(s):  
M. M. Canal ◽  
H. D. Piggins
Keyword(s):  
Locomotor Activity ◽  
Behavioral Activation ◽  
Wheel Running ◽  
Activity Wheel ◽  
Phase Shifting ◽  
Behavioral Rhythms ◽  
Circadian Phase ◽  
Complex Stimuli ◽  
Long Duration ◽  
Highly Correlated

Circadian rhythms of animals are reset by exposure to light as well as dark; however, although the parameters of photic entrainment are well characterized, the phase-shifting actions of dark pulses are poorly understood. Here, we determined the tonic and phasic effects of short (0.25 h), moderate (3 h), and long (6–9 h) duration dark pulses on the wheel-running rhythms of hamsters in constant light. Moderate- and long-duration dark pulses phase dependently reset behavioral rhythms, and the magnitude of these phase shifts increased as a function of the duration of the dark pulse. In contrast, the 0.25-h dark pulses failed to evoke consistent effects at any circadian phase tested. Interestingly, moderate- and long-dark pulses elevated locomotor activity (wheel-running) on the day of treatment. This induced wheel-running was highly correlated with phase shift magnitude when the pulse was given during the subjective day. This, together with the finding that animals pulsed during the subjective day are behaviorally active throughout the pulse, suggests that both locomotor activity and behavioral activation play an important role in the phase-resetting actions of dark pulses. We also found that the robustness of the wheel-running rhythm was weakened, and the amount of wheel-running decreased on the days after exposure to dark pulses; these effects were dependent on pulse duration. In summary, similarly to light, the resetting actions of dark pulses are dependent on both circadian phase and stimulus duration. However, dark pulses appear more complex stimuli, with both photic and nonphotic resetting properties.

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.

Hyperoxia and Locomotor Activity in Rats

1968 ◽  
Vol 26 (3) ◽  
pp. 745-746 ◽  
Author(s):  
Martin J. Gerben
Keyword(s):  
Locomotor Activity ◽  
Wheel Running ◽  
Activity Wheel ◽  
Reduced Activity

Exposure to an 8% O2 atmosphere (hypoxia) reduced activity-wheel running of rats approximately 50% with respect to a 21% O2 (normoxia) control condition. Exposure to 30, 60, and 100% O2 (hyperoxia) did not affect locomotor activity.

Hypoxia and Spontaneous Locomotor Activity in the Rat

1967 ◽  
Vol 25 (3) ◽  
pp. 969-978 ◽  
Author(s):  
Martin J. Gerben
Keyword(s):  
Locomotor Activity ◽  
Wheel Running ◽  
Activity Wheel ◽  
Spontaneous Locomotor Activity ◽  
Previous Exposure ◽  
Sprague Dawley ◽  
Dual Effect ◽  
Running Time ◽  
Sprague Dawley Rats

Three experiments investigated the effects of hypoxia on activity wheel running in male Sprague-Dawley rats. Ss were exposed to atmospheres containing 21% O2 (normoxia), 16% O2, 12% O2, and 8% O2 for 20 min. of running. Decreases in activity occurred in atmospheres below 16% O2. Activity over the length of each 20-min. running period decreased as a function of amount of previously elapsed running time but was not significantly affected by the duration of previous exposure to the experimental atmosphere. Running in a normoxic atmosphere was increased if the immediately preceding exposure involved a hypoxic rather than normoxic atmosphere. The results suggest a dual effect of hypoxia. Hypoxia initially increases the tendency to be active in the non-running rat but eventually reduces activity in the running animal. Hypoxia was compared to other deprivation states with respect to motivational properties.

scholarly journals DEC1 Modulates the Circadian Phase of Clock Gene Expression

2008 ◽  
Vol 28 (12) ◽  
pp. 4080-4092 ◽  
Author(s):  
Ayumu Nakashima ◽  
Takeshi Kawamoto ◽  
Kiyomasa K. Honda ◽  
Taichi Ueshima ◽  
Mitsuhide Noshiro ◽  
...  
Keyword(s):  
Gene Expression ◽  
Clock Genes ◽  
Luciferase Reporter ◽  
Constant Darkness ◽  
Mobility Shift ◽  
Behavioral Rhythms ◽  
Circadian Phase ◽  
Clock Gene Expression ◽  
E Box ◽  
E Boxes

ABSTRACT DEC1 suppresses CLOCK/BMAL1-enhanced promoter activity, but its role in the circadian system of mammals remains unclear. Here we examined the effect of Dec1 overexpression or deficiency on circadian gene expression triggered with 50% serum. Overexpression of Dec1 delayed the phase of clock genes such as Dec1, Dec2, Per1, and Dbp that contain E boxes in their regulatory regions, whereas it had little effect on the circadian phase of Per2 and Cry1 carrying CACGTT E′ boxes. In contrast, Dec1 deficiency advanced the phase of the E-box-containing clock genes but not that of the E′-box-containing clock genes. Accordingly, DEC1 showed strong binding and transrepression on the E box, but not on the E′ box, in chromatin immunoprecipitation, electrophoretic mobility shift, and luciferase reporter assays. Dec1 −/− mice showed behavioral rhythms with slightly but significantly longer circadian periods under conditions of constant darkness and faster reentrainment to a 6-h phase-advanced shift of a light-dark cycle. Knockdown of Dec2 with small interfering RNA advanced the phase of Dec1 and Dbp expression, and double knockdown of Dec1 and Dec2 had much stronger effects on the expression of the E-box-containing clock genes. These findings suggest that DEC1, along with DEC2, plays a role in the finer regulation and robustness of the molecular clock.

Glucocorticosteroid injection is a circadian zeitgeber in the laboratory rat

1982 ◽  
Vol 243 (3) ◽  
pp. R373-R378 ◽  
Author(s):  
N. D. Horseman ◽  
C. F. Ehret
Keyword(s):  
Phase Response Curve ◽  
Phase Shifts ◽  
Phase Shifting ◽  
Constant Darkness ◽  
Circadian Cycle ◽  
Saline Injection ◽  
Laboratory Rats ◽  
Circadian Phase ◽  
Ad Libitum Feeding

Intraperitoneal temperatures were monitored by radiotelemetry to observe the thermoregulatory rhythm of male laboratory rats (Rattus norvegicus albinus) Rats received single injections of dexamethasone (as dexamethasone sodium phosphate) during constant darkness (0.1 lx) with food freely available or no food available. No phase shifts occurred following saline injection or dexamethasone at 1 mg/kg body wt. Depending on the phase of injection relative to the circadian cycle, dexamethasone at 10 mg/kg caused thermoregulatory peaks to be either delayed or advanced on the 4th and 5th day after injection. There was an insensitive interval which corresponded to subjective day. Phase shifts induced by dexamethasone during ad libitum feeding were of less magnitude than those induced during starvation. The determination of phase-shifting parameters (i.e., a phase-response curve) for hormonal substances represents a rigorous and broadly applicable technique for determining endogenous mechanisms for circadian phase control and entrainment.

Passive Body Heating Ameliorates Sleep Disturbances in Patients With Vascular Dementia Without Circadian Phase-Shifting

2005 ◽  
Vol 13 (5) ◽  
pp. 369-376 ◽  
Author(s):  
Yumiko Mishima ◽  
Satoshi Hozumi ◽  
Tetsuo Shimizu ◽  
Yasuo Hishikawa ◽  
Kazuo Mishima
Keyword(s):  
Vascular Dementia ◽  
Sleep Disturbances ◽  
Phase Shifting ◽  
Circadian Phase

People Planning by a Fixed Resource Method

1972 ◽  
Vol 34 (3) ◽  
pp. 799-806 ◽  
Author(s):  
John C. Baird ◽  
Virgil Graf ◽  
Richard Degerman
Keyword(s):  
Cluster Analysis ◽  
Outer Space ◽  
Three Dimensional ◽  
Two Dimensions ◽  
The Third ◽  
Complex Stimuli ◽  
The Mean ◽  
Highly Correlated ◽  
Third Dimension ◽  
The Ideal

Results are presented from a new method to determine a person's conception of complex stimuli. In three related experiments Ss expressed their views of ideal organisms by distributing a fixed resource among hypothetical properties of the ideal. The results from the experiments were highly correlated, lending weight to the reliability and generality of the approach. Cluster analysis and multidimensional scaling were used to group the properties in two dimensions, while the mean amount allocated to a property was represented in the third dimension. A three-dimensional plot was constructed for each of four ideals: the only organism on earth, a member of the only species on earth, an organism going into outer space, and an organism coming to earth from outer space.

scholarly journals Locomotor activity and gait in aged mice deficient for type IX collagen

2010 ◽  
Vol 109 (1) ◽  
pp. 211-218 ◽  
Author(s):  
Kerry E. Costello ◽  
Farshid Guilak ◽  
Lori A. Setton ◽  
Timothy M. Griffin
Keyword(s):  
Locomotor Activity ◽  
Wheel Running ◽  
Age Of Onset ◽  
Disease Onset ◽  
Stride Frequency ◽  
Dark Phase ◽  
Running Wheel ◽  
Voluntary Activity ◽  
Knee Oa ◽  
Locomotor Behaviors

Osteoarthritis (OA) is a risk factor for physical inactivity and impaired mobility, but it is not well understood how these locomotor behaviors are affected by the age of onset of OA and disease severity. Male mice homozygous for a Col9a1 gene inactivation ( Col9a1−/−) develop early onset knee OA, increased tactile pain sensitivity, and gait alterations by 9 mo of age. We hypothesized that aged Col9a1−/− mice would reduce joint pain by adopting locomotor behaviors that reduce both the magnitude and daily frequency of joint loading. We tested this hypothesis by evaluating gait and spontaneous locomotor activity in 15- to 17-mo-old male Col9a1−/− ( n = 5) and Col9a1+/+(WT) ( n = 5) mice using well-controlled measures of voluntary activity in overground and running wheel conditions, as well as studies of gait in a velocity-controlled treadmill. We found no difference due to genotype in freely chosen locomotor velocity, stride frequency, hindfoot duty factor, dark phase activity time, or dark-phase travel distance during overground, running wheel, or speed-matched treadmill locomotion. Interpretation of these findings is potentially confounded by the observation that WT mice have greater knee OA than Col9a1−/− mice in the lateral tibial plateau by 17 mo of age. When accounting for individual differences in knee OA, functional locomotor impairments in aged Col9a1−/− and WT mice are manifested as reductions in total locomotor activity levels (e.g., both distance traveled and time active), particularly for wheel running. These results support the concept that current disease status, rather than age of disease onset, is the primary determinant of impaired locomotor activity with aging.

Entrainment of the master circadian clock by scheduled feeding

2004 ◽  
Vol 287 (3) ◽  
pp. R551-R555 ◽  
Author(s):  
Marina R. Castillo ◽  
Kelly J. Hochstetler ◽  
Ronald J. Tavernier ◽  
Dana M. Greene ◽  
Abel Bult-Ito
Keyword(s):  
Circadian Clock ◽  
Wheel Running ◽  
Expression Profiles ◽  
The Novel ◽  
Suprachiasmatic Nuclei ◽  
Behavioral Rhythms ◽  
Entrainment Process ◽  
Protein Expression Profiles ◽  
Access To Food ◽  
Constant Dark

The master circadian clock, located in the mammalian suprachiasmatic nuclei (SCN), generates and coordinates circadian rhythmicity, i.e., internal organization of physiological and behavioral rhythms that cycle with a near 24-h period. Light is the most powerful synchronizer of the SCN. Although other nonphotic cues also have the potential to influence the circadian clock, their effects can be masked by photic cues. The purpose of this study was to investigate the ability of scheduled feeding to entrain the SCN in the absence of photic cues in four lines of house mouse ( Mus domesticus). Mice were initially housed in 12:12-h light/dark cycle with ad libitum access to food for 6 h during the light period followed by 4–6 mo of constant dark under the same feeding schedule. Wheel running behavior suggested and circadian PER2 protein expression profiles in the SCN confirmed entrainment of the master circadian clock to the onset of food availability in 100% (49/49) of the line 2 mice in contrast to only 4% (1/24) in line 3 mice. Mice from line 1 and line 4 showed intermediate levels of entrainment, 57% (8/14) and 39% (7/18), respectively. The predictability of entrainment vs. nonentrainment in line 2 and line 3 and the novel entrainment process provide a powerful tool with which to further elucidate mechanisms involved in entrainment of the SCN by scheduled feeding.

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