PARALLEL EFFECTS OF LIGHT SIGNALS ON THE CIRCADIAN RHYTHMS OF RUNNING ACTIVITY AND OVULATION IN RATS

1980 ◽  
Vol 85 (1) ◽  
pp. 111-120 ◽  
Author(s):  
R. SRIDARAN ◽  
C. E. McCORMACK

SUMMARY Continuous monitoring of wheel-running activity and determination of the time of ovulation in rats by serial laparotomies revealed that ovulation followed the onset of running at prooestrus by approximately 9 h (range 7–11 h). This temporal relationship held in rats in which the period of the circadian rhythm had been modified (entrained) by daily exposure to 14 h photoperiods, and in rats in dim continuous light whose rhythms were non-entrained (freerunning). Knowledge of this temporal relationship between the two rhythms made it possible to give bright light signals at known points in the circadian cycle of the rat and to observe the effects on the timing of running and ovulation in subsequent cycles. Giving daily light signals near the onset of running (i.e. at subjective dusk) delayed, whereas giving signals near the end of running (i.e. at subjective dawn) advanced, the time of running and ovulation in subsequent cycles. These results indicate that in rats exposed to the usual laboratory photoperiod the delaying effect of dusk light and the advancing effect of dawn light balance one another; thus the preovulatory surge of LH occurs at a relatively consistent time at prooestrus.

2005 ◽  
Vol 289 (4) ◽  
pp. R998-R1005 ◽  
Author(s):  
Juan J. Chiesa ◽  
Montserrat Anglès-Pujolràs ◽  
Antoni Díez-Noguera ◽  
Trinitat Cambras

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.


2021 ◽  
Author(s):  
Fan Wu ◽  
Shuo Wu ◽  
Qiuqi Gui ◽  
Kaixin Tang ◽  
Qiqi Xu ◽  
...  

Light plays a direct crucial role in the switch between sleep and arousal and the regulation of physiology and behaviour, such as circadian rhythms and emotional change. Artificial lights, which are different from natural light sources with a continuous light spectrum, are composed of three single-colour lights and are increasingly applied in modern society. However, in vivo research on the mechanisms of blue light-regulated sleep and arousal is still insufficient. In this work, we detected the effects of inserting white or blue light for 1 h during the dark period on the wheel-running activity and sucrose preference of C57 mice. The results showed that blue light could induce delays in sleep and arousal-promoting responses. Furthermore, this lighting pattern, including blue light alone, induced depressive-like emotions. The c-fos expression in the blue light group was significantly higher in the arcuate hypothalamic nucleus (Arc) and significantly lower in the cingulate cortex (Cg) and anterior part of the paraventricular thalamic nucleus (PVA) than in the white light group. Compared with the white light group, the phospho-ERK expression in the paraventricular hypothalamic nucleus (PVN) and PVA was lower in the blue light group. These molecular changes indicated that certain brain regions are involved in blue light-induced response processes. This study may provide useful information to explore the specific mechanism of special light-regulated physiological function.


1997 ◽  
Vol 273 (6) ◽  
pp. R2132-R2137 ◽  
Author(s):  
Plamen D. Penev ◽  
Phyllis C. Zee ◽  
Fred W. Turek

The continuous monitoring of spontaneous locomotor activity has emerged as one of the most widely used metrics in rodent circadian research. This behavioral measure is also extremely useful for the description of the effects of aging on circadian rhythms. The present study describes the successful use of a log-survivorship approach to identify discrete bouts of hamster wheel-running activity and provides a detailed description of the age-related fragmentation in the 24-h profile of this behavioral variable. In addition, stepwise discriminant analysis identified the most important quantitative measures for distinguishing between the individual patterns of wheel-running activity of young (3 mo) and old (17–18 mo) golden hamsters. The results suggest that this method of bout analysis can be a valuable tool for the study of genetic, developmental, neurochemical, physiological, and environmental factors involved in the temporal control of rodent locomotor behavior.


1984 ◽  
Vol 247 (2) ◽  
pp. R296-R301 ◽  
Author(s):  
J. S. Ferraro ◽  
C. E. McCormack

Using feedback circuits, light exposure was linked to wheel-running activity in female albino rats. Because the photosensitive portions of the circadian cycle are known to coincide with wheel-running activity, the feedback circuits concentrated light on the photosensitive portions of the cycle. In this type of lighting, the free-running period of locomotor activity was directly proportional to the light intensity (i.e., the Aschoff effect), and at an intensity of 100 1x, cyclic ovulation caused. Both these effects, which were previously thought to result only from exposure to continuous light (LL), occurred even though these rats were exposed to only 4 h of light per circadian cycle. These results indicate that the consequences of LL are not due to the continuity of the light per se but represent the effects of light falling on discrete photosensitive portions of the circadian cycle.


1981 ◽  
Vol 29 (6) ◽  
pp. 821 ◽  
Author(s):  
AG Lyne

Exercise wheels and closed-circuit television were used to record the activity rhythms of 34 1. macrourus and 32 P, nasuta (1) outdoors; (2) indoors with natural light; (3) indoors with artificial light in which the phases of night and day were normal; (4) same as (3) but with the phases of night and day reversed; (5) continuous dark; (6) continuous light. In tests (3)-(6) a faint red light was on continuously. These tests were made on animals caged singly or in pairs and lasted for periods of from 8 to 357 days. When a male and a female of different body weights were tested together, the animal using the wheel was identified by its weight. Five I. macrourus and 23 P. nasuta exposed to normal phases of night and day were active mainly during the dark periods. The daily activity pattern varied considerably but was fairly constant for individuals. When the phases of night and day were reversed, the animals continued to be active during the dark periods and, in many of them, the pattern of activity was similar to that under normal phases of night and day. They were, therefore, entrained to the artificial lighting system. However, in 17 out of 31 P. nasuta and 5 out of 31 1. macrourus exposed to reversed lighting conditions, activity started later each day. When the trigger for exercise began to fall close to the beginning of a light period, no activity was taken; the animals did not run in the wheel or take other exercise for 2-5 days, feeding and drinking were greatly reduced and some animals did not leave the nest box for 1-2 days. After this pause, exercise began again at the beginning of a dark period. In 10 I. macrourus exposed to continuous dark the period of the endogenous rhythm was either more than or less than 24 h, and in continuous light (four animals), the wheel-running activity was greatly reduced.


1985 ◽  
Vol 248 (2) ◽  
pp. R181-R189 ◽  
Author(s):  
J. L. Blank ◽  
C. Desjardins

The reproductive responses of two species of wild rodents, house mice and deer mice, were evaluated following a 30% reduction in food intake for 5 wk. These animal models were chosen as prototypes of other rodent species because each employs unique functional adjustments when confronted with reduced resources in their natural habitats. Modest inanition failed to alter pituitary-testicular function in house mice; neither spermatogenesis nor plasma concentrations of luteinizing hormone (LH) and testosterone were modified. In sharp distinction, deer mice exposed to restricted food intake showed significant reductions in plasma LH and testosterone and an accompanying loss in spermatogenesis. Reduced food intake also caused pronounced shifts in the temporal organization and amount of wheel-running activity in both animal models, albeit in a dichotomous fashion. House mice exhibited the same amount of wheel-running activity throughout inanition, but the diel periodicity of locomotor behavior was shifted from the dark to the light period. Deer mice, in comparison, significantly curtailed wheel-running activity during the dark hours but ran in precise phase relationship with the light-dark cycle. Taken together, our results establish that the male reproductive system and its supporting neuroendocrine and behavioral correlates can be disrupted by modest levels of food restriction in certain animal models.


2009 ◽  
Vol 39 (1) ◽  
pp. 47-55 ◽  
Author(s):  
He S. Yang ◽  
Martha H. Vitaterna ◽  
Aaron D. Laposky ◽  
Kazuhiro Shimomura ◽  
Fred W. Turek

There is considerable evidence for a genetic basis underlying individual differences in spontaneous physical activity in humans and animals. Previous publications indicate that the physical activity level and pattern vary among inbred strains of mice and identified a genomic region on chromosome 13 as quantitative trait loci (QTL) for physical activity. To confirm and further characterize the role of chromosome 13 in regulating daily physical activity level and pattern, we conducted a comprehensive phenotypic study in the chromosome 13 substitution strain (CSS-13) in which the individual chromosome 13 from the A/J strain was substituted into an otherwise complete C57BL/6J (B6) genome. The B6 and A/J parental strains exhibited pronounced differences in daily physical activity, sleep-wake structure, circadian period and body weight. Here we report that a single A/J chromosome 13 in the context of a B6 genetic background conferred a profound reduction in both total cage activity and wheel-running activity under a 14:10-h light-dark cycle, as well as in constant darkness, compared with B6 controls. Additionally, CSS-13 mice differed from B6 controls in the diurnal distribution of activity and the day-to-day variability in activity onset. We further performed a linkage analysis and mapped a significant QTL on chromosome 13 regulating the daily wheel running activity level in mice. Taken together, our findings indicate a QTL on chromosome 13 with dramatic and specific effects on daily voluntary physical activity, but not on circadian period, sleep, or other aspects of activity that are different between B6 and A/J strains.


2010 ◽  
Vol 109 (3) ◽  
pp. 623-634 ◽  
Author(s):  
J. Timothy Lightfoot ◽  
Larry Leamy ◽  
Daniel Pomp ◽  
Michael J. Turner ◽  
Anthony A. Fodor ◽  
...  

Previous genetic association studies of physical activity, in both animal and human models, have been limited in number of subjects and genetically homozygous strains used as well as number of genomic markers available for analysis. Expansion of the available mouse physical activity strain screens and the recently published dense single-nucleotide polymorphism (SNP) map of the mouse genome (≈8.3 million SNPs) and associated statistical methods allowed us to construct a more generalizable map of the quantitative trait loci (QTL) associated with physical activity. Specifically, we measured wheel running activity in male and female mice (average age 9 wk) in 41 inbred strains and used activity data from 38 of these strains in a haplotype association mapping analysis to determine QTL associated with activity. As seen previously, there was a large range of activity patterns among the strains, with the highest and lowest strains differing significantly in daily distance run (27.4-fold), duration of activity (23.6-fold), and speed (2.9-fold). On a daily basis, female mice ran further (24%), longer (13%), and faster (11%). Twelve QTL were identified, with three (on Chr. 12, 18, and 19) in both male and female mice, five specific to males, and four specific to females. Eight of the 12 QTL, including the 3 general QTL found for both sexes, fell into intergenic areas. The results of this study further support the findings of a moderate to high heritability of physical activity and add general genomic areas applicable to a large number of mouse strains that can be further mined for candidate genes associated with regulation of physical activity. Additionally, results suggest that potential genetic mechanisms arising from traditional noncoding regions of the genome may be involved in regulation of physical activity.


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