Effects of photoperiod reduction on rat circadian rhythms of BP, heart rate, and locomotor activity

Zhang, Bei-Li; Zannou, Erika A.; Sannajust, Frederick

doi:10.1152/ajpregu.2000.279.1.r169

Cited by 22 publications

(16 citation statements)

References 34 publications

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“…a reduction affecting both light-on and light-off [5,25,41]. Entrainment to the short photoperiod had the same pattern for body temperature and motor activity.…”

Section: Discussionmentioning

confidence: 79%

“…These differentially synchronize the two putative oscillators of the circadian pacemaker, "M" (morning) and "E" (evening), which are considered responsible for the cessation and onset respectively of the motor activity peak [2,12,17,18,19,29]. The direction (symmetrical or asymmetrical) of the extension of the dark phase is known to have differential effects on the onset and cessation of the activity span, the melatonin peak and pineal N-acetyl transferase activity in hamsters and rats [9,11,26,41]. It was not known, however, how an asymmetrical extension of darkness by a 6-h delay in the light signal would affect body temperature and motor activity rhythms in young or old rats.…”

Section: Discussionmentioning

confidence: 99%

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Effect of a short photoperiod on circadian rhythms of body temperature and motor activity in old rats

Benstaali¹,

Bogdan²,

Touitou³

2002

Pflügers Arch - Eur J Physiol

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Circadian rhythms of body temperature and motor activity were documented in young and old rats (four 8-week-old and five 22-month-old male Wistars, implanted with telemetric probes and housed in a chronobiological facility) under two different photoperiod conditions. The animals were maintained in a light:dark (LD) cycle of 12 h each (LD 12:12) for 4 weeks and then exposed to a LD 6:18 cycle for 7 weeks to assess the effect of age on the desynchronization of the temporal structure of the rhythms. In old rats under LD 12:12, the power of the 24-h component and the circadian amplitude of body temperature and motor activity were markedly lower than in the young and both rhythms were phase-advanced. After the shift to LD 6:18, the circadian rhythmicity was maintained for both variables and the same phase delay (+5+/-1 h) was observed in both age groups, as was a gradual expansion of the patterns of both functions with the longer night. The photoperiod reduction (6 weeks under LD 6:18) did not modify the power of the 24-h component of body temperature and motor activity in old rats. In young rats, however, the power and amplitude of the 24-h component of motor activity rhythm fell to the levels of those in old rats, while the power of the 24-h component of body temperature rhythm and the amplitude did not change. Our data show that the circadian rhythm of motor activity, but not of body temperature, responds age dependently to a photoperiod reduction.

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“…a reduction affecting both light-on and light-off [5,25,41]. Entrainment to the short photoperiod had the same pattern for body temperature and motor activity.…”

Section: Discussionmentioning

confidence: 79%

Section: Discussionmentioning

confidence: 99%

Effect of a short photoperiod on circadian rhythms of body temperature and motor activity in old rats

Benstaali¹,

Bogdan²,

Touitou³

2002

Pflügers Arch - Eur J Physiol

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“…(Zee et al, 1992;Penev et al, 1997;Valentinuzzi et al, 1997;Mailloux et al, 1999;Zhang et al, 2000)), confirming rhythm disturbances such as an increased fragmentation and decreased amplitude of the daily locomotor activity rhythm, as well as a decreased precision in the onset of activity phase. Previous work in rodents and primates indicates that the sensitivity of the circadian timing system to short-term manipulation of light…”

Section: Introductionmentioning

confidence: 76%

Attenuated effect of increased daylength on activity rhythm in the old mouse lemur, a non-human primate

Aujard

Cayetanot

Terrien

et al. 2007

Experimental Gerontology

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To cite this version:Fabienne Aujard, Florence Cayetanot, Jérémy Terrien, Eus J.W. Van Someren. Attenuated effect of increased daylength on activity rhythm in the old mouse lemur, a non-human primate. Experimental Gerontology, Elsevier, 2007, 42 (11) ACCEPTED MANUSCRIPT A C C E P T E D M A N U S C R I P T ABSTRACTAdaptation of physiological and behavioral functions to seasonal changes in daylength is of major relevance for optimal fitness and survival. Because aging is characterized by changes in biological rhythms, it may be hypothesized that old animals fall short of showing a full adaptation to prolonged changes in the duration of daily light exposure, as naturally occurring in relation to season in younger individuals. To test this hypothesis, we analyzed changes in the patterns of daily locomotor activity and body temperature rhythms of young and old mouse lemurs (Microcebus murinus, Primates) exposed to short and long daylengths. The effect of an increase in the duration of daily light exposure was attenuated in old animals, as compared to younger lemurs. Although some age-related differences in the locomotor activity rhythm could be seen under exposure to short daylength, they were predominant under long daylength. Some mechanisms allowing adaptation to changing day length thus seem to be impaired at old age. Changes in coupling of circadian oscillators to the light-dark cycle and disturbances in the physiological responses to change in light duration should be further investigated.

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“…Diurnal variations in the activity of the sympathetic nervous system are well documented and likely comprise the major driving force for diurnal variations in multiple cardiovascular parameters, such as blood pressure, heart rate, and cardiac output (26,34,35,45). Norepinephrine is a major sympathetic neurotransmitter.…”

Section: Discussionmentioning

confidence: 99%

The intrinsic circadian clock within the cardiomyocyte

Durgan

Hotze

Tomlin

et al. 2005

American Journal of Physiology-Heart and Circulatory Physiology

181

159

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Circadian clocks are intracellular molecular mechanisms that allow the cell to anticipate the time of day. We have previously reported that the intact rat heart expresses the major components of the circadian clock, of which its rhythmic expression in vivo is consistent with the operation of a fully functional clock mechanism. The present study exposes oscillations of circadian clock genes [brain and arylhydrocarbon receptor nuclear translocator-like protein 1 (bmal1), reverse strand of the c-erba␣ gene (rev-erba␣), period 2 (per2), albumin D-element binding protein (dbp)] for isolated adult rat cardiomyocytes in culture. Acute (2 h) and/or chronic (continuous) treatment of cardiomyocytes with FCS (50% and 2.5%, respectively) results in rhythmic expression of circadian clock genes with periodicities of 20 -24 h. In contrast, cardiomyocytes cultured in the absence of serum exhibit dramatically dampened oscillations in bmal1 and dbp only. Zeitgebers (timekeepers) are factors that influence the timing of the circadian clock. Glucose, which has been previously shown to reactivate circadian clock gene oscillations in fibroblasts, has no effect on the expression of circadian clock genes in adult rat cardiomyocytes, either in the absence or presence of serum. Exposure of adult rat cardiomyocytes to the sympathetic neurotransmitter norephinephrine (10 M) for 2 h reinitiates rhythmic expression of circadian clock genes in a serumindependent manner. Oscillations in circadian clock genes were associated with 24-h oscillations in the metabolic genes pyruvate dehydrogenase kinase 4 (pdk4) and uncoupling protein 3 (ucp3). In conclusion, these data suggest that the circadian clock operates within the myocytes of the heart and that this molecular mechanism persists under standard cell culture conditions (i.e., 2.5% serum). Furthermore, our data suggest that norepinephrine, unlike glucose, influences the timing of the circadian clock within the heart and that the circadian clock may be a novel mechanism regulating myocardial metabolism.heart; metabolism; neurohumoral; rat; zeitgebers CIRCADIAN CLOCKS are controlled by a set of genes that generate self-sustained positive and negative transcriptional feedback loops with a free-running period of 24 h (7,11,40). This molecular mechanism is intrinsic to the cell, persisting in cultured cells such as fibroblasts, vascular smooth muscle cells, and various cell lines (3,13,20,23). Circadian clocks confer the selective advantage of anticipation, conditioning the cell to changes in its environment, such that it can respond rapidly to a specific extracellular signal at an appropriate time of the day. For example, our laboratory (30) has recently hypothesized that the circadian clock within cardiac and skeletal muscle allows the myocytes to anticipate diurnal variations in circulating fatty acids through modulation of fatty acid oxidative capacity at a transcriptional level. However, the existence of an intracellular circadian clock mechanism that is intrinsic to either the cardiomyocyte or...

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Effects of photoperiod reduction on rat circadian rhythms of BP, heart rate, and locomotor activity

Cited by 22 publications

References 34 publications

Effect of a short photoperiod on circadian rhythms of body temperature and motor activity in old rats

Effect of a short photoperiod on circadian rhythms of body temperature and motor activity in old rats

Attenuated effect of increased daylength on activity rhythm in the old mouse lemur, a non-human primate

The intrinsic circadian clock within the cardiomyocyte

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